Author Topic: Should the BFR have a launch escape system?  (Read 16080 times)

Online Pipcard

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Should the BFR have a launch escape system?
« on: 07/24/2017 11:42 PM »
The STS, better known as the Space Shuttle, was assumed during its development to be so reliable that it did not need any launch abort capabilities. The Challenger disaster of 1986 led to the questioning of this notion. However, they could not retrofit the Shuttle due to complexity, weight, and cost concerns.

Some people assume that the ITS is going to operate like an airliner, such that it won't need any form of LES, but will SpaceX have trouble getting proper safety certifications for the ITS in order for it to launch people?

How many test flights would take place before such a vehicle can be deemed safe to carry humans? For example, the Japanese SSTO concept Kankoh-maru (designed for large-scale space tourism) was thought to have required 1200 test flights.

edit: changed title to BFR.
« Last Edit: 10/07/2017 03:35 PM by Pipcard »

Offline IanThePineapple

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Re: Should the ITS have a launch escape system?
« Reply #1 on: 07/24/2017 11:48 PM »
Its LES is pretty much the engines on the bottom of the ship, you can't have an escape system that large.
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Offline Robotbeat

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Re: Should the ITS have a launch escape system?
« Reply #2 on: 07/24/2017 11:49 PM »
Well, if ITS doesn't have a LAS, it probably will at least have a docking port. So can always launch crew in Dragon. That could also be one of QuantumG's payload subscale BFRs, too.

So, annoying but definitely no showstopper. Musk mentioned a crew (LEO) transport transferring people to interplanetary ITS if refueling takes too long, so presumably you could fit an LAS onto this other ITS if Dragon is deemed too expensive.

That would be when you want to send lots of people. It need not happen until there's a LOT of infrastructure already prepared on Mars or the Moon, i.e. 2030s or 2040s.
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Offline Lars-J

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Re: Should the ITS have a launch escape system?
« Reply #3 on: 07/25/2017 12:08 AM »
Not this topic again.  ;D This has been discussed a lot on this forum, look at old ITS threads to see every possible argument in favor and against launch escape systems.

Offline spacenut

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Re: Should the ITS have a launch escape system?
« Reply #4 on: 07/25/2017 12:45 AM »
I predict the first humans to Mars will only have between 6-18 crew.  Six can be brought up at a time on Dragon capsules.  They will dock with ITS.  ITS will be in orbit until it is refueled, and if necessary add cargo.  It could launch empty and cargo brought up by another ITS making refueling easier with only one or two tanker ITS.  A couple of unmanned ITS could go to Mars before hand and set up refueling operations etc.   

Later manned only ITS taking colonists can still be loaded not only by Dragons, but CTS-100's or Soyuz or even Chinese or whoever else wants to send.  Six with one Dragon, 4 with one CTS-100, 3 with Soyuz and 3 maybe with Chinese, that is 16 and all can dock and load their colonists within a day of each other.  By then India may have a capsule.  Even another provider like Blue Origin.  Europeans may want to pay for flights.  People don't have to be launched on ITS.  It is for in space use mostly for humans, and for earth launches of cargo.   

Offline stcks

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Re: Should the ITS have a launch escape system?
« Reply #5 on: 07/25/2017 02:33 AM »
Look, if you're going to hop in the ITS and make a propulsive landing on another heavenly body then you are already trusting your life to a system without a dedicated abort system. At that point you might as well take the ride out of Earth's atmosphere too.

Offline Kenp51d

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Re: Should the ITS have a launch escape system?
« Reply #6 on: 07/25/2017 02:57 AM »
Look, if you're going to hop in the ITS and make a propulsive landing on another heavenly body then you are already trusting your life to a system without a dedicated abort system. At that point you might as well take the ride out of Earth's atmosphere too.
Agreed
 At least for a fair number of years, if you abort on Mars you are still toast. The toaster just pops up a bit later.
A second or third ship might make me wrong though, that's a good thing indeed.

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Offline Robotbeat

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Re: Should the ITS have a launch escape system?
« Reply #7 on: 07/25/2017 03:10 AM »
I don't know if I think ITS should have an abort capability or not, but:

The idea that abort on Mars would be pointless is a dumb myth that needs to die. There's no reason that need necessarily be true, and there are several strategies to ensuring survival for those who abort.

Down-range placement of supplies or rover.

Survival equipment on the capsule.

Mars aircraft sent for pickup or supply delivery.

Small orbital caches sent to the surface.

Suborbital hoppers.

Backup ITS used to rescue stranded survivors.

Fast rovers.

Escape capsule maneuvering.

A combination of the above concepts.


Seriously, you might think it's not worth it. I haven't decided myself. But to say aborting crew would necessarily be toast is incredibly small-minded.
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Offline Kenp51d

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Re: Should the ITS have a launch escape system?
« Reply #8 on: 07/25/2017 03:46 AM »
I don't know if I think ITS should have an abort capability or not, but:

The idea that abort on Mars would be pointless is a dumb myth that needs to die. There's no reason that need necessarily be true, and there are several strategies to ensuring survival for those who abort.

Down-range placement of supplies or rover.

Survival equipment on the capsule.

Mars aircraft sent for pickup or supply delivery.

Small orbital caches sent to the surface.

Suborbital hoppers.

Backup ITS used to rescue stranded survivors.

Fast rovers.

Escape capsule maneuvering.

A combination of the above concepts.


Seriously, you might think it's not worth it. I haven't decided myself. But to say aborting crew would necessarily be toast is incredibly small-minded.
You just might be right on some of those options.
Every effort to save a crew is worth while. We certainly try very hard to save people here on Earth. Even great efforts are spent too save animals that are trapped, hurt whatever. Many fire units are even equipped with mask to save a dog or cat. I applued all of that. Life is very precious.
You had valid points that I was not aware of as options. But your rebuttal would have been just as evective if delivered without harshness, meant that way or not.
I have generally found honey first, then the vinager has a higher success rate with people.
No offense meant with my reply. I have usually read your posts a little closer.

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Offline Robotbeat

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Re: Should the ITS have a launch escape system?
« Reply #9 on: 07/25/2017 04:18 AM »
I don't know if I think ITS should have an abort capability or not, but:

The idea that abort on Mars would be pointless is a dumb myth that needs to die. There's no reason that need necessarily be true, and there are several strategies to ensuring survival for those who abort.

Down-range placement of supplies or rover.

Survival equipment on the capsule.

Mars aircraft sent for pickup or supply delivery.

Small orbital caches sent to the surface.

Suborbital hoppers.

Backup ITS used to rescue stranded survivors.

Fast rovers.

Escape capsule maneuvering.

A combination of the above concepts.


Seriously, you might think it's not worth it. I haven't decided myself. But to say aborting crew would necessarily be toast is incredibly small-minded.
You just might be right on some of those options.
Every effort to save a crew is worth while. We certainly try very hard to save people here on Earth. Even great efforts are spent too save animals that are trapped, hurt whatever. Many fire units are even equipped with mask to save a dog or cat. I applued all of that. Life is very precious.
You had valid points that I was not aware of as options. But your rebuttal would have been just as evective if delivered without harshness, meant that way or not.
I have generally found honey first, then the vinager has a higher success rate with people.
No offense meant with my reply. I have usually read your posts a little closer.

Sent from my XT1565 using Tapatalk
Good point.
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Offline Jim

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Re: Should the ITS have a launch escape system?
« Reply #10 on: 07/25/2017 01:44 PM »
Look, if you're going to hop in the ITS and make a propulsive landing on another heavenly body then you are already trusting your life to a system without a dedicated abort system. At that point you might as well take the ride out of Earth's atmosphere too.

Not really.  Earth orbital launch is completely different than a martian orbital launch.  The delta V and atmosphere make for two different vehicles.  Martian orbital launch launch vehicle is a small SSTO.  Earth orbital launch will be a large multistage vehicle.

Offline stcks

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Re: Should the ITS have a launch escape system?
« Reply #11 on: 07/25/2017 01:55 PM »
Look, if you're going to hop in the ITS and make a propulsive landing on another heavenly body then you are already trusting your life to a system without a dedicated abort system. At that point you might as well take the ride out of Earth's atmosphere too.

Not really.  Earth orbital launch is completely different than a martian orbital launch.  The delta V and atmosphere make for two different vehicles.  Martian orbital launch launch vehicle is a small SSTO.  Earth orbital launch will be a large multistage vehicle.

I understand that. But that doesn't really change anything. Once you hit Mars atmosphere you're committed. What use is some fancy abort pod in that regime? You're not making it back to earth. (And yes, fine, if some existing base is already on Mars with proper emergency vehicles and whatever in place already, maybe you survive, but im not talking about that).

If the booster fails on ascent from Earth, you rely on the ship to abort. If something fails inbound to Mars, you also rely on the ship. It just seems odd to me to ferry passengers to LEO on a separate ship when their lives will depend entirely on the integrity of the interplanetary ship anyway.

Jim, I'm curious how you would see an abort capability working.
« Last Edit: 07/25/2017 02:04 PM by stcks »

Offline JamesH65

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Re: Should the ITS have a launch escape system?
« Reply #12 on: 07/26/2017 10:49 AM »
I look on it as if you were trying to make an launch abort system for a small airliner carrying say 100 people. Some way of getting everyone to safety if it fails in flight.

And I cannot think of a way of doing that...

Offline Arb

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Re: Should the ITS have a launch escape system?
« Reply #13 on: 07/26/2017 10:05 PM »
If you were going to do it the obvious way would be to cram the launch-and-landing-couches into the ship's nose and make that section a separable, large capsule. It would need enough propellant to abort in earth gravity (plus parachutes to land). On mars and the moon it'd need enough propellant to abort and land.

Lot's of trades to be done to determine if feasible and at what cost in $ and lost cargo/passenger capacity.

I quite like the idea of everyone on board being in close proximity for launch and landing (those short but dangerous phases of flight); it feels right somehow.

Offline Patchouli

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Re: Should the ITS have a launch escape system?
« Reply #14 on: 07/26/2017 10:27 PM »
Two ways to solve it you either make the systems able to handle multiple failures during launch and able to make an emergency landing if needed like an airliner or you launch it uncrewed and then once it's on orbit have a vehicle that is inherently safer such as a capsule,small space plane or even a HOTOL like Skylon carry up the crew and passingers.

Dealing with T+ 0 failures is lot easier for a HOTOL as like an airliner they don't fall back on the pad if thrust to weight drops below 1 to 1 which is why I suggest it as a solution.

Plus having ITS launch uncrewed removes some of the time constraints to get it refueled and not having 50 to 100 people and all their luggage on board  would save a lot of mass on the hardest leg of the trip.
« Last Edit: 07/26/2017 10:39 PM by Patchouli »

Offline livingjw

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Re: Should the ITS have a launch escape system?
« Reply #15 on: 07/27/2017 02:21 AM »
Two ways to solve it you either make the systems able to handle multiple failures during launch and able to make an emergency landing if needed like an airliner or you launch it uncrewed and then once it's on orbit have a vehicle that is inherently safer such as a capsule,small space plane or even a HOTOL like Skylon carry up the crew and passingers.

Dealing with T+ 0 failures is lot easier for a HOTOL as like an airliner they don't fall back on the pad if thrust to weight drops below 1 to 1 which is why I suggest it as a solution.

Plus having ITS launch uncrewed removes some of the time constraints to get it refueled and not having 50 to 100 people and all their luggage on board  would save a lot of mass on the hardest leg of the trip.

- Disagree. If you loose all propulsion in an airliner you will most likely die.
- There are no HTOL systems that can accomplish SSTO. They will have to be TSTO. This includes Skylon.
- HTOL launchers are more complex than VTOL rockets and use advanced technology (lower TRLs, higher risk).
- As Patchouli said, you need to be able to handle failures and still get down safely. Some obvious things that could be done are:
           - robust landing rockets and fuel separate from main propulsion.
           - main propellant dump system to empty tanks quickly (and sequentially)
           - landing on its side instead of upright
Just some ideas.

John

« Last Edit: 07/27/2017 02:29 AM by livingjw »

Offline CuddlyRocket

Re: Should the ITS have a launch escape system?
« Reply #16 on: 07/27/2017 04:18 AM »
If you loose all propulsion in an airliner you will most likely die.

That's not true. In many such cases the pilots manage to re-start an engine. Where they do not, most successfully glide to the nearest runway (the record is 65 miles). Even when they can't reach a runway, many successfully land elsewhere or ditch on water (e.g. Captain Sully on the Hudson river).

Offline su27k

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Re: Should the ITS have a launch escape system?
« Reply #17 on: 07/27/2017 04:57 AM »
I look on it as if you were trying to make an launch abort system for a small airliner carrying say 100 people. Some way of getting everyone to safety if it fails in flight.

And I cannot think of a way of doing that...

Some examples:
https://encrypted.google.com/patents/EP1110861A1?cl=en
https://www.google.com/patents/US20110233341

These do not make much sense for airplane because air travel is very safe, but I think they're definitely needed if we're going to send 50 people on top of BFR. One advantage of rocket travel is the launch itself only lasts a very short time, so you can pack people like sardines into a much smaller space.

Offline pathfinder_01

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Re: Should the ITS have a launch escape system?
« Reply #18 on: 07/27/2017 06:31 AM »
It just seems odd to me to ferry passengers to LEO on a separate ship when their lives will depend entirely on the integrity of the interplanetary ship anyway.


There are advntages and disadvantages of ferring in a seperate ship.

The ITS bound for mars could take a less human safe trajectory (g forces and location where an abort system would land a crew)into orbit which could allow for greater amounts of cargo to get to orbit. Humans would retain the safety of abort system.

It would relax the time constraints with regard to refueling the ITS before departure.

Also although Elon plans to depart from LEO, LEO isn't the only place he could depart from.

I rather doubt that any human carring spacecraft will attempt to go without a escape system for quite some time(i.e. so long as crews are small.)

Online Pipcard

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Re: Should the ITS have a launch escape system?
« Reply #19 on: 09/21/2017 01:36 AM »
I just found out that this question was already answered last year, after the presentation livestream.


The points made by Musk were:
- Spaceship is meant to be its own abort system during Earth launch
(but don't launch escape systems, including that of Crew Dragon, need to have a high TWR? Or engines that can start as soon as possible?)
- A separate LES on Mars is pointless: "if you're not taking off, you're not taking off" and "parachutes don't work too well."
- An specialized LES for 100 people is not feasible.
- Key is focusing on reliability and "redundancy in the engines, high safety margins," and lots of testing "like a commercial airliner."

Martianspirit on r/spacex speculated about putting the passengers on a tanker (therefore, not requiring the use of partially expendable Falcon 9 + Dragon).
Quote
Elon Musk has mentioned the possibility to launch the passengers late into the refuelled vehicle. It would be quite inefficient to use a full ITS for that purpose. Take a tanker and cut off the nose. Replace it with an abort capsule. For 100 passengers it may have a weight of 60t and would not reduce the tanker capacity too much. The capsule would be crammed but it would only be for a few hours.

Or maybe splitting the crew between five tankers? And making it an SSTO when doing LEO tourism? (Robotbeat thinks a modified tanker would have enough delta-v margin for smaller payloads - is it carbon fiber that makes this possible?)

A few have mentioned that going to Mars is already risky enough. But what if someone just wants to be a tourist in LEO? Having an LES may make it more attractive to more potential customers.
« Last Edit: 09/21/2017 08:05 AM by Pipcard »

Offline matthewkantar

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Re: Should the ITS have a launch escape system?
« Reply #20 on: 09/21/2017 03:02 AM »
Maybe SpaceX could give the passengers a choice, letting those individuals pick from a menu. Earth surface to Mars on a single vehicle with no LES would cost $500,000. If you want go up on a falcon and transfer to ITS, the additional cost might be $3,000,000, or one seventh of a twenty or so million dollar F-9 launch.

I know what I would choose.

Matthew

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Re: Should the ITS have a launch escape system?
« Reply #21 on: 09/21/2017 03:31 AM »
If the big(gest) ITS could eventually show a loss-of-mission safety ratio about one-third that of a busy, commercial airliner - that would be more than good enough for me. But we would be waiting some years for that to happen...
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Offline GORDAP

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Re: Should the ITS have a launch escape system?
« Reply #22 on: 09/21/2017 12:04 PM »
I've always wondered just what is wrong with the BFS being its own LES. 

I know that it doesn't have high T/W ratio, and that the turbopumps take a few seconds to spin up, but it's not like you're going to outrun a true detonation event in the booster anyway, no matter how quickly a human 'pod' can skedaddle out of there.  It seems that it should only be required to outrun a conflagration of the booster, right?

Can anyone point to a realistic booster failure scenario in which a traditional LES would save the passengers, but in which the planned BFS LES would not?

Offline envy887

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Re: Should the ITS have a launch escape system?
« Reply #23 on: 09/21/2017 01:51 PM »
I've always wondered just what is wrong with the BFS being its own LES. 

I know that it doesn't have high T/W ratio, and that the turbopumps take a few seconds to spin up, but it's not like you're going to outrun a true detonation event in the booster anyway, no matter how quickly a human 'pod' can skedaddle out of there.  It seems that it should only be required to outrun a conflagration of the booster, right?

Can anyone point to a realistic booster failure scenario in which a traditional LES would save the passengers, but in which the planned BFS LES would not?

Any launch where the vehicle fails to control its angle of attack in the atmosphere (like Ariane 501 or the Challenger breakup) would be much easier to survive in a capsule than an integrated stage/capsule. I'm not sure the ship will be designed to survive a high AoA at max-Q pressures, and a clean separation is also very tricky.

Also any failures that happen on or near the launch pad, like AMOS-6 or the Proton nosedive in 2013, would not leave the ship with enough altitude and velocity to get away with it's low TWR at sea level. Not an issue with a capsule.

Offline GORDAP

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Re: Should the ITS have a launch escape system?
« Reply #24 on: 09/21/2017 03:16 PM »
I've always wondered just what is wrong with the BFS being its own LES. 

I know that it doesn't have high T/W ratio, and that the turbopumps take a few seconds to spin up, but it's not like you're going to outrun a true detonation event in the booster anyway, no matter how quickly a human 'pod' can skedaddle out of there.  It seems that it should only be required to outrun a conflagration of the booster, right?

Can anyone point to a realistic booster failure scenario in which a traditional LES would save the passengers, but in which the planned BFS LES would not?

Any launch where the vehicle fails to control its angle of attack in the atmosphere (like Ariane 501 or the Challenger breakup) would be much easier to survive in a capsule than an integrated stage/capsule. I'm not sure the ship will be designed to survive a high AoA at max-Q pressures, and a clean separation is also very tricky.

Also any failures that happen on or near the launch pad, like AMOS-6 or the Proton nosedive in 2013, would not leave the ship with enough altitude and velocity to get away with it's low TWR at sea level. Not an issue with a capsule.

Hmm, are you saying the BFS would have a TWR less than 1 at sea level?  I think that's hard to imagine with all 9 engines screaming at full thrust (yes, I realize that 6 of these would be overexpanded at sea level, but it seems this would be acceptable for a small amount of time during a dire emergency).

It appears you are saying that a capsule with appropriate LES had a much better chance of survival than a vehicle that depends upon aerodynamics during this critical phase, right? (correct me if I'm wrong.)  But I'm not suggesting that the BFR fly like an airplane during an abort, I'm suggesting that if flies, then lands as a rocket ship in the same mode as its final decent on Mars and Earth.  Sure, it will have to hover for a good while to burn off fuel, but that shouldn't be an issue. 

I'm still not seeing why a capsule with LES would be inherently safer than a BFS, unless one can make a credible argument that getting away from a disintegrating booster underneath you - in a great hurry - is critical.

Offline RonM

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Re: Should the ITS have a launch escape system?
« Reply #25 on: 09/21/2017 04:14 PM »
I'm still not seeing why a capsule with LES would be inherently safer than a BFS, unless one can make a credible argument that getting away from a disintegrating booster underneath you - in a great hurry - is critical.

Look at Apollo, Orion, Soyuz, Shenzhou, Starliner, and Dragon. Somebody thinks it's critical.

Offline GORDAP

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Re: Should the ITS have a launch escape system?
« Reply #26 on: 09/21/2017 05:01 PM »
I'm still not seeing why a capsule with LES would be inherently safer than a BFS, unless one can make a credible argument that getting away from a disintegrating booster underneath you - in a great hurry - is critical.

Look at Apollo, Orion, Soyuz, Shenzhou, Starliner, and Dragon. Somebody thinks it's critical.

Ron, I fully understand that getting away is critical.  I underlined the 'great hurry' part to distinguish the argument that a few seconds delay and/or slower acceleration is somehow an important differentiator.  I'm asking for someone to explain how/why this would make the difference between success and loss of life.

Offline RonM

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Re: Should the ITS have a launch escape system?
« Reply #27 on: 09/21/2017 05:27 PM »
I'm still not seeing why a capsule with LES would be inherently safer than a BFS, unless one can make a credible argument that getting away from a disintegrating booster underneath you - in a great hurry - is critical.

Look at Apollo, Orion, Soyuz, Shenzhou, Starliner, and Dragon. Somebody thinks it's critical.

Ron, I fully understand that getting away is critical.  I underlined the 'great hurry' part to distinguish the argument that a few seconds delay and/or slower acceleration is somehow an important differentiator.  I'm asking for someone to explain how/why this would make the difference between success and loss of life.

Look at some old rocket explosion videos. It should become obvious. An emergency on the pad or early in flight require a high gee acceleration to escape. Later in the flight, more gentle aborts will work. That's why Apollo, Orion, Soyuz, and Shenzhou jettison their LAS before reaching orbit; it's no longer needed.

Even high gee LAS won't save the crew all of the time. If there's no indication of a problem before a massive explosion, no LAS is going to do the job.

There will always be a chance the crew will be killed. That's ok for daring astronauts on exploration missions, but what about 100 passengers wanting a new start at a Mars colony? If there isn't a LAS on ITS spacecraft, then the booster better be as reliable as a modern aircraft. Either that or the passengers need to be well informed about the danger.

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Re: Should the ITS have a launch escape system?
« Reply #28 on: 09/21/2017 05:37 PM »
I'm still not seeing why a capsule with LES would be inherently safer than a BFS, unless one can make a credible argument that getting away from a disintegrating booster underneath you - in a great hurry - is critical.

Look at Apollo, Orion, Soyuz, Shenzhou, Starliner, and Dragon. Somebody thinks it's critical.

Ron, I fully understand that getting away is critical.  I underlined the 'great hurry' part to distinguish the argument that a few seconds delay and/or slower acceleration is somehow an important differentiator.  I'm asking for someone to explain how/why this would make the difference between success and loss of life.

Look at some old rocket explosion videos. It should become obvious. An emergency on the pad or early in flight require a high gee acceleration to escape. Later in the flight, more gentle aborts will work. That's why Apollo, Orion, Soyuz, and Shenzhou jettison their LAS before reaching orbit; it's no longer needed.

Even high gee LAS won't save the crew all of the time. If there's no indication of a problem before a massive explosion, no LAS is going to do the job.

There will always be a chance the crew will be killed. That's ok for daring astronauts on exploration missions, but what about 100 passengers wanting a new start at a Mars colony? If there isn't a LAS on ITS spacecraft, then the booster better be as reliable as a modern aircraft. Either that or the passengers need to be well informed about the danger.

People by the millions flew on commercial aircraft 30-40 years ago when they were a fraction as safe as 'modern aircraft.'  People by the millions (billions) do all sorts of crazy things today that aren't as safe as 'modern aircraft,' like driving to work, or skiing, or jumping out of airplanes that aren't on fire...

Inform passengers of the risk, have them sign on the dotted line, and get on with it. 

Don't go if your standard is as safe as 'modern aircraft'... won't happen.


« Last Edit: 09/21/2017 05:38 PM by AncientU »
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Offline envy887

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Re: Should the ITS have a launch escape system?
« Reply #29 on: 09/21/2017 06:23 PM »
Look at some old rocket explosion videos. It should become obvious. An emergency on the pad or early in flight require a high gee acceleration to escape. Later in the flight, more gentle aborts will work. That's why Apollo, Orion, Soyuz, and Shenzhou jettison their LAS before reaching orbit; it's no longer needed.

Even high gee LAS won't save the crew all of the time. If there's no indication of a problem before a massive explosion, no LAS is going to do the job.

The high acceleration is mainly to get away from any debris thrown during a booster breakup that might damage the capsule, as well as the potential overpressure wave and thermal damage. Not every booster failure results in debris, pressure, or thermals that threaten the crew vehicle, and there are situations where the low thrust and delayed start of the upper stage Raptors would be sufficient to save the crew.

Hmm, are you saying the BFS would have a TWR less than 1 at sea level?  I think that's hard to imagine with all 9 engines screaming at full thrust (yes, I realize that 6 of these would be overexpanded at sea level, but it seems this would be acceptable for a small amount of time during a dire emergency).

It appears you are saying that a capsule with appropriate LES had a much better chance of survival than a vehicle that depends upon aerodynamics during this critical phase, right? (correct me if I'm wrong.)  But I'm not suggesting that the BFR fly like an airplane during an abort, I'm suggesting that if flies, then lands as a rocket ship in the same mode as its final decent on Mars and Earth.  Sure, it will have to hover for a good while to burn off fuel, but that shouldn't be an issue.

The ITS ship as presented at IAC 2016 would definitely have a TWR very near 1, because the overexpanded vacuum nozzles reduce the available thrust from those engines. That design might change to something more useful for a pad abort.

The biggest issue with using the Raptors for abort is the potential loss of control during the delay for startup, especially near Max-Q. That stage is going to have a much tougher time flying sideways at Mach 1 than a capsule would. Perhaps the RCS system and/or body flaps could be used for control while the Raptors spin up.

Offline spacenut

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Re: Should the ITS have a launch escape system?
« Reply #30 on: 09/21/2017 06:25 PM »
The 9m ITS will probably send 5-10 unmanned cargo ships to Mars first with equipment, habitats, solar panels, etc.  One ship will make fuel for return.  These will probably be sent in one synod.  Then the next synod, humans will go.  To begin with I say a small crew, no more than say 30 on the smaller ITS.  So ITS while refueling can easily have 2-3 Dragons or other spacecraft dock and transfer their people.  One Dragon (6), one CTS-100 (4), Soyuz (3), the Chinese craft (3), That is 16, maybe others on their spacecrafts.  So I don't see ITS having a LES, probably ever.  Docking for fueling will probably be done from the sides.  Docking for visiting spacecraft transfering people can be done from the nose while it is refueling for a trip to Mars.  These early ships will be a mix of crew and cargo.  Maybe even husband-wife astronauts or specialists in botony, or mining, or chemistry. 

Offline GORDAP

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Re: Should the ITS have a launch escape system?
« Reply #31 on: 09/21/2017 09:17 PM »
Look at some old rocket explosion videos. It should become obvious. An emergency on the pad or early in flight require a high gee acceleration to escape. Later in the flight, more gentle aborts will work. That's why Apollo, Orion, Soyuz, and Shenzhou jettison their LAS before reaching orbit; it's no longer needed.

Even high gee LAS won't save the crew all of the time. If there's no indication of a problem before a massive explosion, no LAS is going to do the job.

The high acceleration is mainly to get away from any debris thrown during a booster breakup that might damage the capsule, as well as the potential overpressure wave and thermal damage. Not every booster failure results in debris, pressure, or thermals that threaten the crew vehicle, and there are situations where the low thrust and delayed start of the upper stage Raptors would be sufficient to save the crew.

Hmm, are you saying the BFS would have a TWR less than 1 at sea level?  I think that's hard to imagine with all 9 engines screaming at full thrust (yes, I realize that 6 of these would be overexpanded at sea level, but it seems this would be acceptable for a small amount of time during a dire emergency).

It appears you are saying that a capsule with appropriate LES had a much better chance of survival than a vehicle that depends upon aerodynamics during this critical phase, right? (correct me if I'm wrong.)  But I'm not suggesting that the BFR fly like an airplane during an abort, I'm suggesting that if flies, then lands as a rocket ship in the same mode as its final decent on Mars and Earth.  Sure, it will have to hover for a good while to burn off fuel, but that shouldn't be an issue.

The ITS ship as presented at IAC 2016 would definitely have a TWR very near 1, because the overexpanded vacuum nozzles reduce the available thrust from those engines. That design might change to something more useful for a pad abort.

The biggest issue with using the Raptors for abort is the potential loss of control during the delay for startup, especially near Max-Q. That stage is going to have a much tougher time flying sideways at Mach 1 than a capsule would. Perhaps the RCS system and/or body flaps could be used for control while the Raptors spin up.

I've seen clips of many rockets failing during ascent, and they seem to fall into 3 general categories:  A) Violent explosions (rare), B) Gradual (relatively speaking) disintegration, and C) Quickly moving 'conflagrations' (i.e. Shuttle).

There seems to be agreement that no LES designs will survive type A, with high speed debris and the over pressure wave.  I think both BFS and a capsule would survive type B.  That leaves type C - a rapidly expanding conflagration.  Because of its orientation, the shuttle was instantly in the middle of the fireball, plus sandwiched between the two solids (not a good place to be).   Is there a good reason to believe that a BFS would not survive a 'typical' conflagration type event of the booster (other than the momentary aerodynamic issue raised above)?

I just suspect that when someone runs the actual numbers for failure scenarios, they'd find something like, yeah, a capsule plus traditional LES survives 80% of the failures, and the BFS will only survive 75%.  If this is the case, the "You can't launch 100 civilians without traditional LES" argument is revealed to be too simplistic. 

Offline whitelancer64

Re: Should the ITS have a launch escape system?
« Reply #32 on: 09/21/2017 09:40 PM »
I've seen clips of many rockets failing during ascent, and they seem to fall into 3 general categories:  A) Violent explosions (rare), B) Gradual (relatively speaking) disintegration, and C) Quickly moving 'conflagrations' (i.e. Shuttle).

There seems to be agreement that no LES designs will survive type A, with high speed debris and the over pressure wave.  I think both BFS and a capsule would survive type B.  That leaves type C - a rapidly expanding conflagration.  Because of its orientation, the shuttle was instantly in the middle of the fireball, plus sandwiched between the two solids (not a good place to be).   Is there a good reason to believe that a BFS would not survive a 'typical' conflagration type event of the booster (other than the momentary aerodynamic issue raised above)?

I just suspect that when someone runs the actual numbers for failure scenarios, they'd find something like, yeah, a capsule plus traditional LES survives 80% of the failures, and the BFS will only survive 75%.  If this is the case, the "You can't launch 100 civilians without traditional LES" argument is revealed to be too simplistic.

LES systems are designed for your category A. LES systems can react faster than the blink of an eye. A crewed Dragon v2 on top of Amos-6 would have gotten clear of the explosion easily, for example.
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Offline Norm38

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Re: Should the ITS have a launch escape system?
« Reply #33 on: 09/22/2017 05:43 PM »
LES systems are designed for your category A. LES systems can react faster than the blink of an eye. A crewed Dragon v2 on top of Amos-6 would have gotten clear of the explosion easily, for example.

I have a question about that, regarding the g-forces on the human body. At launch the astronauts are strapped in, facing forward, braced and ready for the acceleration.
Now I supposed that the astronauts will have to be already strapped in before fueling starts, but they won't be braced for an unexpected high g abort.  So they've got their arms about, their head up, looking around, then are suddenly slammed back at several g.  What happens?

Offline cppetrie

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Re: Should the ITS have a launch escape system?
« Reply #34 on: 09/22/2017 08:30 PM »
LES systems are designed for your category A. LES systems can react faster than the blink of an eye. A crewed Dragon v2 on top of Amos-6 would have gotten clear of the explosion easily, for example.

I have a question about that, regarding the g-forces on the human body. At launch the astronauts are strapped in, facing forward, braced and ready for the acceleration.
Now I supposed that the astronauts will have to be already strapped in before fueling starts, but they won't be braced for an unexpected high g abort.  So they've got their arms about, their head up, looking around, then are suddenly slammed back at several g.  What happens?
For Dragon 2, at least, fueling will take approximately 75 minutes. During that time the passengers would be strapped in tightly with little room to move. They wonít be able to move their heads much and there would be little reason to be reaching about in the capsule as everything is automated or controlled from the ground. At most they might be reading something off a display and relating it to ground but even that is probably unnecessary. They will mostly just be confirming they are go for launch when the time comes. The same will be true during ascent. A sudden high-G maneuver could result in injury if they were moving around or not secured properly, but neither should be the case.

Offline eriblo

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Re: Should the ITS have a launch escape system?
« Reply #35 on: 09/22/2017 08:42 PM »
LES systems are designed for your category A. LES systems can react faster than the blink of an eye. A crewed Dragon v2 on top of Amos-6 would have gotten clear of the explosion easily, for example.

I have a question about that, regarding the g-forces on the human body. At launch the astronauts are strapped in, facing forward, braced and ready for the acceleration.
Now I supposed that the astronauts will have to be already strapped in before fueling starts, but they won't be braced for an unexpected high g abort.  So they've got their arms about, their head up, looking around, then are suddenly slammed back at several g.  What happens?
For Dragon 2, at least, fueling will take approximately 75 minutes. During that time the passengers would be strapped in tightly with little room to move. They wonít be able to move their heads much and there would be little reason to be reaching about in the capsule as everything is automated or controlled from the ground. At most they might be reading something off a display and relating it to ground but even that is probably unnecessary. They will mostly just be confirming they are go for launch when the time comes. The same will be true during ascent. A sudden high-G maneuver could result in injury if they were moving around or not secured properly, but neither should be the case.
I agree with cppetrie and my basic-physics guess is that worst case scenario is a dislocated/broken arm or two and strained neck muscles. The initial g-force is about 6 g in the best possible direction ("eyeballs in") which is comparable to at most a 8 m/s (29 kph, 18 mph) rear end collision (assuming equal weight cars and 1 m ideal crumple zone). The acceleration will of course continue for much longer but then you have time to tense up and use your muscles.

Online docmordrid

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Re: Should the ITS have a launch escape system?
« Reply #36 on: 09/22/2017 10:11 PM »
For comparison, the highst G coaster is the 'Tower of Terror' at Gold Reef City, South Africa

6.3G

http://entertainmentdesigner.com/news/top-seven-most-thrilling-roller-coasters-in-the-world/
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Offline Norm38

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Re: Should the ITS have a launch escape system?
« Reply #37 on: 09/23/2017 04:05 AM »
Okay, so in the equation of whether I as a paying passenger want an LES or not;
The choice is airline like operations at higher risk, or astronaut level precautions.

One way colonists may tolerate that. But there's some frequency limit to that.

Offline cppetrie

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Re: Should the ITS have a launch escape system?
« Reply #38 on: 09/23/2017 05:09 AM »
LES systems are designed for your category A. LES systems can react faster than the blink of an eye. A crewed Dragon v2 on top of Amos-6 would have gotten clear of the explosion easily, for example.

I have a question about that, regarding the g-forces on the human body. At launch the astronauts are strapped in, facing forward, braced and ready for the acceleration.
Now I supposed that the astronauts will have to be already strapped in before fueling starts, but they won't be braced for an unexpected high g abort.  So they've got their arms about, their head up, looking around, then are suddenly slammed back at several g.  What happens?
For Dragon 2, at least, fueling will take approximately 75 minutes. During that time the passengers would be strapped in tightly with little room to move. They wonít be able to move their heads much and there would be little reason to be reaching about in the capsule as everything is automated or controlled from the ground. At most they might be reading something off a display and relating it to ground but even that is probably unnecessary. They will mostly just be confirming they are go for launch when the time comes. The same will be true during ascent. A sudden high-G maneuver could result in injury if they were moving around or not secured properly, but neither should be the case.
I agree with cppetrie and my basic-physics guess is that worst case scenario is a dislocated/broken arm or two and strained neck muscles. The initial g-force is about 6 g in the best possible direction ("eyeballs in") which is comparable to at most a 8 m/s (29 kph, 18 mph) rear end collision (assuming equal weight cars and 1 m ideal crumple zone). The acceleration will of course continue for much longer but then you have time to tense up and use your muscles.
A traumatic brain injury is possible if it is possible for the passenger to flex forward enough to create sufficient gap that upon activation of the abort system the head was accelerated back towards some sort of headrest. But why would they even permit that level of movement? There is no need for it. The passengers should be restrained almost to the point of being immobile so as to virtually eliminate the possibility of injury from abort system activation. I would think even passengers on ITS would be largely constrained in some sort of restraint system akin to a mix between 5 point racing harness and roller coaster restraints. So long as the ship itself remained intact I would think severe injuries would be very unlikely.

Offline octavo

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Re: Should the ITS have a launch escape system?
« Reply #39 on: 09/23/2017 08:02 AM »
For comparison, the highst G coaster is the 'Tower of Terror' at Gold Reef City, South Africa

6.3G

http://entertainmentdesigner.com/news/top-seven-most-thrilling-roller-coasters-in-the-world/
It's a really short duration though. I've ridden it several times in a row on a quiet day - great fun, but, whoosh and it's over.

Online meekGee

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Re: Should the ITS have a launch escape system?
« Reply #40 on: 09/24/2017 01:48 AM »
I really like the idea of five 20-person escapable capsules, one on each tanker flight.
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Offline su27k

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Re: Should the ITS have a launch escape system?
« Reply #41 on: 09/24/2017 03:21 PM »
I've always wondered just what is wrong with the BFS being its own LES. 

Full size BFS has a propellant load higher than Falcon Heavy, even a subscale BFS would probably have propellant load higher than Falcon 9, it itself represents a danger to the crew. Remember both catastrophic failure of Falcon 9 happened on the upper stage.

Online docmordrid

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Re: Should the ITS have a launch escape system?
« Reply #42 on: 09/24/2017 11:19 PM »
I've always wondered just what is wrong with the BFS being its own LES. 

Full size BFS has a propellant load higher than Falcon Heavy, even a subscale BFS would probably have propellant load higher than Falcon 9, it itself represents a danger to the crew. Remember both catastrophic failure of Falcon 9 happened on the upper stage.

And both of those failures involved the helium system, which BFS, of full or ITSy size, will not have.
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Offline John Alan

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Re: Should the ITS have a launch escape system?
« Reply #43 on: 09/25/2017 12:24 AM »
I really like the idea of five 20-person escapable capsules, one on each tanker flight.

Agreed... Much smaller system mounted near the nose or front top side... only able to safely save the strapped in crew and capsule system at any point UNTIL S2 fires normally in a earth launch situation...
At that point... it transitions to a primary S2 based "try and fly it home" as the velocities are getting a bit much to build something that survives suborbital reentry...
If S2 makes it to orbit and then goes bang... I guess in theory the escape capsule could do short term till help arrives lifeboat on orbit duty...

Trying to launch the entire S2 off a failing S1 is just silly crazy in an emergency... Just my opinion on topic...
« Last Edit: 09/25/2017 12:30 AM by John Alan »

Offline spacenut

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Re: Should the ITS have a launch escape system?
« Reply #44 on: 09/25/2017 02:08 AM »
Liquid methane and liquid oxygen can self pressurize with boil off, no need for helium.  ITSy at 9m diameter will be much larger than FH.  So an ITSy tanker will also have to be made to fill. 

Offline drzerg

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Re: Should the ITS have a launch escape system?
« Reply #45 on: 09/25/2017 02:32 AM »
you could use separate ship just for transfering people from earth to orbit. so it will be like:

1 ITS MARS - cargo + people and all needs for long term to mars and back to earth
2 ITS CARGO LEO - just cargo any including comersial
3 ITS TANKER LEO - just fuel
4 ITS PEOPLE TO LEO - cargo + full abort support with capsules. possible more sealevel engines (up to 15) for higher T/W




Offline DreamyPickle

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Re: Should the ITS have a launch escape system?
« Reply #46 on: 09/26/2017 09:57 AM »
How about building small escape pods into the walls of the ship? They would be shaped like Soyuz or Dragon except with the engines pointing the other way. In case of danger the crew enters those pods through hatches. If something goes wrong the engines fire and they "pop" right out at an angle.

These pods would have heat-shields normally facing outwards through what are structurally "windows" through the hull. They would be small, barely large enough that people can fit while strapped in. This could also work from orbit, they would just have to linger until on top of a suitable splashdown location for reentry.

The problem with such a system is that it would be still quite large and require a lot of work to develop and test properly.

Offline Athrithalix

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Re: Should the ITS have a launch escape system?
« Reply #47 on: 09/26/2017 10:59 AM »
In the event of an emergency during a launch, it seems unlikely that there would be time for passengers to climb into individual escape pods and strap themselves in, and you would probably want each escape pod to hold as many people as possible for efficiency's sake. Imagine the mass and cost penalty for adding hundreds of capsules, engines, parachutes, life support and re-entry protection systems.

Offline DreamyPickle

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Re: Should the ITS have a launch escape system?
« Reply #48 on: 09/26/2017 12:01 PM »
In the event of an emergency during a launch, it seems unlikely that there would be time for passengers to climb into individual escape pods and strap themselves in, and you would probably want each escape pod to hold as many people as possible for efficiency's sake. Imagine the mass and cost penalty for adding hundreds of capsules, engines, parachutes, life support and re-entry protection systems.

You can just require everybody to strap in and close the hatches whenever you're firing the engines. You only allow passengers to move around when safely in orbit or landed. Commercial airliners already require wearing seatbelts for landing and takeoff so it's not a big deal.

The mass/cost penalty will indeed be quite large but:

* Special seats are required for high-G maneuvers anyway, might as well place them in escape pods.
* Escape pods only need emergency life support for a few days. This can serve double duty as backup for the main ECLSS.
* Maybe you can start from a Dragon v2 to cut down on development costs?
* The escape pods would fit multiple people with Soyuz-like packing and barely any room to move around:


Offline su27k

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Re: Should the ITS have a launch escape system?
« Reply #49 on: 09/26/2017 12:31 PM »
How about building small escape pods into the walls of the ship? They would be shaped like Soyuz or Dragon except with the engines pointing the other way. In case of danger the crew enters those pods through hatches. If something goes wrong the engines fire and they "pop" right out at an angle.

These pods would have heat-shields normally facing outwards through what are structurally "windows" through the hull. They would be small, barely large enough that people can fit while strapped in. This could also work from orbit, they would just have to linger until on top of a suitable splashdown location for reentry.

The problem with such a system is that it would be still quite large and require a lot of work to develop and test properly.

This is similar to my thoughts, instead of one big escape pod, use multiple smaller ones, much easier to manufacture and test. And obviously the crew will need to sit inside the escape pod during ascend, just pack them like sardines. The difference is I think the pods can be put inside launch tubes like SSBNs, with tube opening on the opposite side of the main heat shield (BFS enters side ways, so only one side needs strong heat shield). For pod propulsion I think you'll probably want to go with solids, like the New Shepard, since it's probably not a good idea to have tons of hypergolic fuel inside BFS. The solid propulsion section would be like the service section of CST-100, it drops off once expended, leaving the capsule to land on parachutes.
« Last Edit: 09/26/2017 12:33 PM by su27k »

Offline RonM

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Re: Should the ITS have a launch escape system?
« Reply #50 on: 09/26/2017 02:18 PM »
Once you add 10 to 20 small escape pods there will be little mass left over for cargo. It isn't practical.

Offline envy887

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Re: Should the ITS have a launch escape system?
« Reply #51 on: 09/26/2017 03:22 PM »
Once you add 10 to 20 small escape pods there will be little mass left over for cargo. It isn't practical.

Agree that it's not practical, but more likely due to complexity and cost and not mass. Soyuz and Dragon 2 mass about 1,000 kg per person, so a 100-person ITS would have 100 tonnes of escape capsules. On the 2016 ITS that leaves 200 tonnes for cargo.

IMO separating the entire crew cabin would be considerably simpler, cheaper, and more reliable, if an abort system is required.

Offline su27k

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Re: Should the ITS have a launch escape system?
« Reply #52 on: 09/27/2017 04:27 AM »
Once you add 10 to 20 small escape pods there will be little mass left over for cargo. It isn't practical.

Agree that it's not practical, but more likely due to complexity and cost and not mass. Soyuz and Dragon 2 mass about 1,000 kg per person, so a 100-person ITS would have 100 tonnes of escape capsules. On the 2016 ITS that leaves 200 tonnes for cargo.

IMO separating the entire crew cabin would be considerably simpler, cheaper, and more reliable, if an abort system is required.

The unstated assumption here is that this BFS with LES is for LEO access only, there's no point dragging the escape pods to Moon/Mars where they will be useless anyway, so if you're going to Moon/Mars, the BFS-LES will take you to LEO to meet up with the fully refueled Moon/Mars BFS and transfer the crew. But BFS-LES' day job would be taking space tourists to LEO for joyrides. In this scenario the cargo capability for BFS-LES is not that important.

As for which solution is better, obviously no way to know, I'm just guessing here. But the reasoning is similar to why BFR has multiple engines instead of one big engine. One big engine is inherently difficult to design due to combustion instability, it's more costly to test since you need a super big test stand, and it's more costly to manufacture since you won't have a production line. It's also less flexible, for example you won't be able to use it on 2nd stage. All these reasoning can be applied to escape system in one way or another, for example the first thing you'll have trouble with one big escape cabin is what propulsion system to use.

Offline Norm38

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Re: Should the ITS have a launch escape system?
« Reply #53 on: 09/29/2017 12:53 PM »
There isn't going to be any LES, over and done. Nowhere in the architecture are there detachable capsules or escape pods.  Musk said repeatedly they're going for airliner level reliability and relying on redundancies.
Anyone who isn't happy with that can stay home.  Time to focus on other things.

Offline woods170

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Re: Should the ITS have a launch escape system?
« Reply #54 on: 09/29/2017 01:12 PM »
There isn't going to be any LES, over and done. Nowhere in the architecture are there detachable capsules or escape pods.  Musk said repeatedly they're going for airliner level reliability and relying on redundancies.
Anyone who isn't happy with that can stay home.  Time to focus on other things.
Agreed. Any continued discussion regarding to subject of this thread is pretty much pointless now that ITS, and the refined BFR, both have been shown as having no Launch Escape System but other means of ensuring crew safety.

Offline Lee Jay

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Re: Should the ITS have a launch escape system?
« Reply #55 on: 10/06/2017 07:32 PM »
An airliner is safe not because it doesn't fail, but because it has such a wide variety of intact abort modes.  Not having an abort system on a crewed vessel is a show-stopper.

Edit/Lar: Rump thread, posts from https://forum.nasaspaceflight.com/index.php?topic=43923 that were debating escape vs. no escape are here, for a bit, then will be deleted. If you  ned yours moved back PM me.
« Last Edit: 10/07/2017 01:08 AM by Lar »

Offline cppetrie

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Re: Should the ITS have a launch escape system?
« Reply #56 on: 10/06/2017 07:33 PM »
I believe Elon on this one. It simply wonít. The added cost, complexity and weight make it technically and economically infeasible and perhaps less safe. If the system isnít safe enough to not need one, it just doesnít work.

Also, what good is an escape system while landing on Mars or moon? Now youíre marooned and will die slowly from lack of supplies. Honestly, I think Iíd rather just go quickly incinerated or at impact, but thatís just me. YMMV.

Offline cppetrie

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Re: Should the ITS have a launch escape system?
« Reply #57 on: 10/06/2017 07:43 PM »
An airliner is safe not because it doesn't fail, but because it has such a wide variety of intact abort modes.  Not having an abort system on a crewed vessel is a show-stopper.
It has redundancy and large safety margins but not an escape system. Thereís no parachutes onboard for all passengers. Any passengers actually.

Offline DJPledger

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Re: Should the ITS have a launch escape system?
« Reply #58 on: 10/06/2017 07:44 PM »
An airliner is safe not because it doesn't fail, but because it has such a wide variety of intact abort modes.  Not having an abort system on a crewed vessel is a show-stopper.
If SpX kill 100 people due to BFR system not having a LAS will mean the end of SpX. BFR needs a LAS to prevent loss of life should a BFR fail and it may just save SpX as well.

Offline DJPledger

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Re: Should the ITS have a launch escape system?
« Reply #59 on: 10/06/2017 07:47 PM »
An airliner is safe not because it doesn't fail, but because it has such a wide variety of intact abort modes.  Not having an abort system on a crewed vessel is a show-stopper.
It has redundancy and large safety margins but not an escape system. Thereís no parachutes onboard for all passengers. Any passengers actually.
This is because airliners are so safe but rockets aren't anywhere near the safety levels of them. BFR needs a LAS because it will likely be several orders of magnitude less safe than airliners. Should only drop the LAS from a manned LV design when it's safety factor is getting close to that of airliners.

Offline cppetrie

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Re: Should the ITS have a launch escape system?
« Reply #60 on: 10/06/2017 07:59 PM »
Current rockets arenít as safe as airliners. They intend to demonstrate safety on the order of airliners. If itís fully reuseable and can be flown for a couple million in fuel and ops costs, then they could afford to fly it empty just for the purpose of building flight history similar to how new airplane models are certified. They fly numerous times essentially empty to build flight history as part of the cost of development and certification.

Edit: typo
« Last Edit: 10/06/2017 07:59 PM by cppetrie »

Offline DJPledger

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Re: Should the ITS have a launch escape system?
« Reply #61 on: 10/06/2017 08:26 PM »
Early crewed flights won't have 100 people. They'll have much smaller crews for either Luna on Mars exploration and base construction. No need for an escape system because crews can be transferred in LEO via a Dragon or two and there's nowhere to go if there's a problem on Luna or Mars.
What if the BFR booster explodes on the pad or shortly after liftoff? I am afraid it will be LOC without a LAS so a LAS is a must if SpX are even contemplating putting crew on this thing.

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Re: Should the ITS have a launch escape system?
« Reply #62 on: 10/06/2017 08:38 PM »
Early crewed flights won't have 100 people. They'll have much smaller crews for either Luna on Mars exploration and base construction. No need for an escape system because crews can be transferred in LEO via a Dragon or two and there's nowhere to go if there's a problem on Luna or Mars.
What if the BFR booster explodes on the pad or shortly after liftoff? I am afraid it will be LOC without a LAS so a LAS is a must if SpX are even contemplating putting crew on this thing.

I see you missed the part about using Dragon to transfer crew in LEO. In this small crew scenario, the BFR launches from Earth without the crew.

Online Lar

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Re: Should the ITS have a launch escape system?
« Reply #63 on: 10/06/2017 08:48 PM »
Early crewed flights won't have 100 people. They'll have much smaller crews for either Luna on Mars exploration and base construction. No need for an escape system because crews can be transferred in LEO via a Dragon or two and there's nowhere to go if there's a problem on Luna or Mars.
What if the BFR booster explodes on the pad or shortly after liftoff? I am afraid it will be LOC without a LAS so a LAS is a must if SpX are even contemplating putting crew on this thing.
Why is it a "must"? It's been explained why SpaceX has decided not to do it but that apparently doesn't satisfy you.

Rather than repeating yourself, give some reasons beyond "it's a must".
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline DJPledger

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Re: Should the ITS have a launch escape system?
« Reply #64 on: 10/06/2017 08:59 PM »
Early crewed flights won't have 100 people. They'll have much smaller crews for either Luna on Mars exploration and base construction. No need for an escape system because crews can be transferred in LEO via a Dragon or two and there's nowhere to go if there's a problem on Luna or Mars.
What if the BFR booster explodes on the pad or shortly after liftoff? I am afraid it will be LOC without a LAS so a LAS is a must if SpX are even contemplating putting crew on this thing.
Why is it a "must"? It's been explained why SpaceX has decided not to do it but that apparently doesn't satisfy you.

Rather than repeating yourself, give some reasons beyond "it's a must".
Launching crew is still a high risk activity which is why all current crewed launches have a LAS. I think SpX needs to get the LOC risk down to around 1 in 100,000 to 1,000,000 for the BFR to be deemed safe enough to not have a LAS. This safety factor for BFR may be possible a long way down the road but unlikely to be achieved during the first few years of BFR service life.

Just one LOC event could kill SpX.
« Last Edit: 10/06/2017 09:00 PM by DJPledger »

Online Lar

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Re: Should the ITS have a launch escape system?
« Reply #65 on: 10/06/2017 09:01 PM »
Why is it a "must"? It's been explained why SpaceX has decided not to do it but that apparently doesn't satisfy you.

Rather than repeating yourself, give some reasons beyond "it's a must".
Launching crew is still a high risk activity which is why all current crewed launches have a LAS. I think SpX needs to get the LOC risk down to around 1 in 100,000 to 1,000,000 for the BFR to be deemed safe enough to not have a LAS. This safety factor for BFR may be possible a long way down the road but unlikely to be achieved during the first few years of BFR service life.

Just one LOC event could kill SpX.
Proof by assertion..., isn't.

This still is of the form "it's a must". Airliners do not have LAS, and didn't even back in the 1930s. Nor are passengers issued parachutes. Shuttle didn't have LAS. Just saying "well I don't care, BFS has to have one because everyone else does" isn't convincing.
« Last Edit: 10/06/2017 09:02 PM by Lar »
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline DJPledger

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Re: Should the ITS have a launch escape system?
« Reply #66 on: 10/06/2017 09:07 PM »
Why is it a "must"? It's been explained why SpaceX has decided not to do it but that apparently doesn't satisfy you.

Rather than repeating yourself, give some reasons beyond "it's a must".
Launching crew is still a high risk activity which is why all current crewed launches have a LAS. I think SpX needs to get the LOC risk down to around 1 in 100,000 to 1,000,000 for the BFR to be deemed safe enough to not have a LAS. This safety factor for BFR may be possible a long way down the road but unlikely to be achieved during the first few years of BFR service life.

Just one LOC event could kill SpX.
Proof by assertion..., isn't.

This still is of the form "it's a must". Airliners do not have LAS, and didn't even back in the 1930s. Nor are passengers issued parachutes. Shuttle didn't have LAS. Just saying "well I don't care, BFS has to have one because everyone else does" isn't convincing.
Airliners are so safe they don't need LAS. Shuttle not having LAS was a huge mistake with two LOC events. Safety factor of future crew launch systems including BFR needs to be around 3 orders of magnitude higher than Shuttle to do away with the LAS.

Offline Lee Jay

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Re: Should the ITS have a launch escape system?
« Reply #67 on: 10/06/2017 09:20 PM »
An airliner is safe not because it doesn't fail, but because it has such a wide variety of intact abort modes.  Not having an abort system on a crewed vessel is a show-stopper.
It has redundancy and large safety margins but not an escape system. Thereís no parachutes onboard for all passengers. Any passengers actually.

I didn't say anything about an escape system.

Offline Lee Jay

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Re: Should the ITS have a launch escape system?
« Reply #68 on: 10/06/2017 09:24 PM »
Current rockets arenít as safe as airliners. They intend to demonstrate safety on the order of airliners.

Being as safe as an airliner means it has to be able to tolerate multiple failures and still land intact.  Last week an A380 had an uncontained engine failure and still landed intact with no people injured.  I was aboard an airliner with a control-systems failure.  We landed without issue.  This sort of thing happens all the time.  That's the reason airline travel is so safe - because the vast majority of failures, even dramatic ones, don't result in a crash.

Offline DJPledger

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Re: Should the ITS have a launch escape system?
« Reply #69 on: 10/06/2017 09:29 PM »
Current rockets arenít as safe as airliners. They intend to demonstrate safety on the order of airliners.

Being as safe as an airliner means it has to be able to tolerate multiple failures and still land intact.  Last week an A380 had an uncontained engine failure and still landed intact with no people injured.  I was aboard an airliner with a control-systems failure.  We landed without issue.  This sort of thing happens all the time.  That's the reason airline travel is so safe - because the vast majority of failures, even dramatic ones, don't result in a crash.
BFR needs to be made as fault tolerant as airliners for it to be safe enough not to need a LAS. Hopefully EM has this in mind for BFR design.

Offline cppetrie

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Re: Should the ITS have a launch escape system?
« Reply #70 on: 10/06/2017 10:05 PM »
Current rockets arenít as safe as airliners. They intend to demonstrate safety on the order of airliners.

Being as safe as an airliner means it has to be able to tolerate multiple failures and still land intact.  Last week an A380 had an uncontained engine failure and still landed intact with no people injured.  I was aboard an airliner with a control-systems failure.  We landed without issue.  This sort of thing happens all the time.  That's the reason airline travel is so safe - because the vast majority of failures, even dramatic ones, don't result in a crash.
And why canít that be true for BFR?

Offline cppetrie

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Re: Should the ITS have a launch escape system?
« Reply #71 on: 10/06/2017 10:18 PM »

Airliners are so safe they don't need LAS. Shuttle not having LAS was a huge mistake with two LOC events. Safety factor of future crew launch systems including BFR needs to be around 3 orders of magnitude higher than Shuttle to do away with the LAS.
A LAS would only have maybe prevented one of the LOC events. It is irrelevant for Columbia which was lost on re-entry not launch. That would have required an ejection system to eject crew from the vehicle at hypersonic speeds during atmospheric re-entry. Iím not sure how such a system could even work.

Offline envy887

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Re: Should the ITS have a launch escape system?
« Reply #72 on: 10/06/2017 10:29 PM »
...
Safety factor of future crew launch systems including BFR needs to be around 3 orders of magnitude higher than Shuttle to do away with the LAS.

Probably higher than that, actually. But plausible to demonstrate with 1000s of launches in a high launch rate, low cost per launch architecture.

Offline envy887

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Re: Should the ITS have a launch escape system?
« Reply #73 on: 10/06/2017 11:37 PM »
From past examples, a LAS offers about a 10-fold improvement in reliability: that is, a system that's 97% reliable (Shuttle) becomes 99.7% reliable.

I don't think it's plausible to design a LAS that allows a vehicle with reliability substantially short of "airliner-like" to become "airliner-like". Any zero-altitude, zero-velocity LAS is going to have the same highly-stressed rocket components as the booster and upper stage, and is going to add lots of new non-benign failure modes.

Perhaps a better question would be, could the BFS be designed to have fewer catastrophic failure modes? Every other form of transportation doesn't take the "get the hell outta there" form of reacting to a failure.

Offline Robotbeat

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Re: Should the ITS have a launch escape system?
« Reply #74 on: 10/07/2017 12:57 AM »
...Safety factor of future crew launch systems including BFR needs to be around 3 orders of magnitude higher than Shuttle to do away with the LAS.
Absolutely, utterly false. AT BEST, a LAS only buys you a SINGLE order of magnitude.

An escape system is NOT a guarantee of survival. All it does is take care of about nine out of ten launch vehicle failures AT BEST.

So, existing rockets are about 95 to at best 99% reliable. A LAS gets you AT BEST to 99.5 to 99.9% reliable. And probably worse than that as it doesn't improve entry or in-space safety.

The solution to this is to just fly and recover BFR 200 to 1000 times in a row safely (or technically, 100 to 500 flights would probably do it especially if you included some near-miss analysis). That shouldn't take too long. And it wouldn't even cost more: if BFR has a marginal cost per launch of $2 million, that means you can do all those launches for $400 million to $2 billion, and they can serve double-duty. Orion's LAS alone probably cost more than $2 billion.
« Last Edit: 10/07/2017 01:08 AM by Robotbeat »
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Offline Lee Jay

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Re: Should the ITS have a launch escape system?
« Reply #75 on: 10/07/2017 03:00 AM »
Current rockets arenít as safe as airliners. They intend to demonstrate safety on the order of airliners.

Being as safe as an airliner means it has to be able to tolerate multiple failures and still land intact.  Last week an A380 had an uncontained engine failure and still landed intact with no people injured.  I was aboard an airliner with a control-systems failure.  We landed without issue.  This sort of thing happens all the time.  That's the reason airline travel is so safe - because the vast majority of failures, even dramatic ones, don't result in a crash.
And why canít that be true for BFR?

Because it's not inherently flyable and because the energy levels are so much higher.

Could it land in an all engines out situation?  Airliners can and have.  They have to be certified to do so.

It is safe in a catastrophic rupture of the cabin?  Airliners have landed safely after such an event.

Can it land safely in a lake, river or ocean?  People have survived that occurrence many times.

Almost everything will have to go right for this thing to be safe to ride on.

At the very least, the upper stage (or spacecraft, if you prefer) needs to be able to separate from a failing first stage and fly itself to safety.  However, as I understand it, that isn't possible.  Did I misunderstand that part?

Offline Robotbeat

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Re: Should the ITS have a launch escape system?
« Reply #76 on: 10/07/2017 03:08 AM »
Meh, I disagree with your whole shpiel. A lot of people died in the 1950s in aircraft. But people still flew, and if SpaceX gets to that reliability level, they'll be fine even for point to point due to lifetime saved in getting to destination faster.

People are treating LAS as if it's magic and saves you in all instances. It ain't magic. It'll fail to save you 1 time out of 10, and that's just on the way up. And such systems can kill you all by themselves even if the rocket is fine: http://www.dailymail.co.uk/news/article-2548135/Coroner-slams-ejector-seat-manufacturer-failing-warn-RAF-defects-led-death-Red-Arrows-pilot.html

A LASless BFR that has flown and been recovered 2000 times safely is a lot safer than Orion or Soyuz will ever be.
« Last Edit: 10/07/2017 03:10 AM by Robotbeat »
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Re: Should the ITS have a launch escape system?
« Reply #77 on: 10/07/2017 09:50 AM »
I' with Robotbeat here: it's possible that rockets fundamentally cannot reach modern aircrafts levels of safety, but I fail to see how they couldn't reach acceptable reliability for routine commercial operations. And, not being an engineer thus not understanding the technicalities as robotbeat does, the thing I can comment on is how irrational it seems to draw similar pessimistic conclusions when talking about rockets, machines that fly less then 100 times per year and are still in their infancy vs airliners. That will change with BFR and full reusability. Instead of making assumptions we should wait and see (or try and see, if you are an aerospace company: the sad thing is that after the Shuttle we had to wait for SX and BO for someone to do this).
« Last Edit: 10/07/2017 09:53 AM by AbuSimbel »
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Re: Should the ITS have a launch escape system?
« Reply #78 on: 10/07/2017 10:12 AM »
Current rockets arenít as safe as airliners. They intend to demonstrate safety on the order of airliners.

Being as safe as an airliner means it has to be able to tolerate multiple failures and still land intact.  Last week an A380 had an uncontained engine failure and still landed intact with no people injured.  I was aboard an airliner with a control-systems failure.  We landed without issue.  This sort of thing happens all the time.  That's the reason airline travel is so safe - because the vast majority of failures, even dramatic ones, don't result in a crash.
And why canít that be true for BFR?

Because it's not inherently flyable and because the energy levels are so much higher.

Could it land in an all engines out situation?  Airliners can and have.  They have to be certified to do so.

It is safe in a catastrophic rupture of the cabin?  Airliners have landed safely after such an event.

Can it land safely in a lake, river or ocean?  People have survived that occurrence many times.

Almost everything will have to go right for this thing to be safe to ride on.

At the very least, the upper stage (or spacecraft, if you prefer) needs to be able to separate from a failing first stage and fly itself to safety.  However, as I understand it, that isn't possible.  Did I misunderstand that part?

I agree. I can believe that SpaceX will be reasonably sure that BFR will not explode violently on pad and will not provide any measures against this, just like airplanes don't. But I can't see them putting people in a craft that would just slowly drop to its doom if BFR fails to provide just-enough dV for orbit for any reason.

At the very least they should have enough software flexibility in BFS to bo able to separate (even with thrust/weight <1 it still can separate), and take a path allowing to burn down fuel and land in some safe spot eventually- at least for a part of the flight envelope (not immediately after liftoff, obviously)...

Can we determine, with currently available data, how high/fast would the stack need to be for this to be possible?
« Last Edit: 10/07/2017 10:18 AM by jded »

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Re: Should the ITS have a launch escape system?
« Reply #79 on: 10/07/2017 11:16 AM »
I' with Robotbeat here: it's possible that rockets fundamentally cannot reach modern aircrafts levels of safety, but I fail to see how they couldn't reach acceptable reliability for routine commercial operations. And, not being an engineer thus not understanding the technicalities as robotbeat does, the thing I can comment on is how irrational it seems to draw similar pessimistic conclusions when talking about rockets, machines that fly less then 100 times per year and are still in their infancy vs airliners. That will change with BFR and full reusability. Instead of making assumptions we should wait and see (or try and see, if you are an aerospace company: the sad thing is that after the Shuttle we had to wait for SX and BO for someone to do this).

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Online KelvinZero

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Re: Should the ITS have a launch escape system?
« Reply #80 on: 10/07/2017 11:55 AM »
There are a list of reasons to conclude this design can at least be safer than the shuttle by a significant margin.

Also, unlike the shuttle, it looks to me like we will have a good long time (or many launches) to establish the safety of the BFS architecture before committing to manned launches.

As to it's ultimate safety, I know nobody knows.. but we can know we will know before we need to know :-)

Re: Should the ITS have a launch escape system?
« Reply #81 on: 10/07/2017 03:27 PM »
I' with Robotbeat here: it's possible that rockets fundamentally cannot reach modern aircrafts levels of safety, but I fail to see how they couldn't reach acceptable reliability for routine commercial operations. And, not being an engineer thus not understanding the technicalities as robotbeat does, the thing I can comment on is how irrational it seems to draw similar pessimistic conclusions when talking about rockets, machines that fly less then 100 times per year and are still in their infancy vs airliners. That will change with BFR and full reusability. Instead of making assumptions we should wait and see (or try and see, if you are an aerospace company: the sad thing is that after the Shuttle we had to wait for SX and BO for someone to do this).

Expendable rockets fly once; all the world's rockets are expendable less one.
Rocketry as an industry is in its infancy.
Yeah and that's a thing overlooked by some that still think expendable small launcher will be competitive with RLV. Reusability is not only about cost: it's the only way to take rocket reliability to the next level. When you can fly affordably and frequently you can also test and improve reliability in a way not possible before. Putting your payload on a rocket that has never flown before and whose reliability is calculated on less data points by orders of magnitude will be like putting it in the hands of a shaman. And that will also apply to ULA.
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Offline Lee Jay

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Re: Should the BFR have a launch escape system?
« Reply #82 on: 10/07/2017 05:30 PM »
Meh, I disagree with your whole shpiel. A lot of people died in the 1950s in aircraft. But people still flew, and if SpaceX gets to that reliability level, they'll be fine even for point to point due to lifetime saved in getting to destination faster.

People are treating LAS as if it's magic and saves you in all instances. It ain't magic. It'll fail to save you 1 time out of 10, and that's just on the way up. And such systems can kill you all by themselves even if the rocket is fine: http://www.dailymail.co.uk/news/article-2548135/Coroner-slams-ejector-seat-manufacturer-failing-warn-RAF-defects-led-death-Red-Arrows-pilot.html

A LASless BFR that has flown and been recovered 2000 times safely is a lot safer than Orion or Soyuz will ever be.

What you just said is that this rocket is going to be at least 100 times safer than any rocket before it, but that any LAS the same company builds won't be any safer than historical LAS's.

Makes zero sense.

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Re: Should the BFR have a launch escape system?
« Reply #83 on: 10/07/2017 05:31 PM »
I' with Robotbeat here: it's possible that rockets fundamentally cannot reach modern aircrafts levels of safety, but I fail to see how they couldn't reach acceptable reliability for routine commercial operations.

Those two things are in direct conflict.

Aircraft are required to be as safe as they are by entities like the FAA.  Why would they allow a far less safe vehicle to be in "routine commercial operations" when they don't for airliners?

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Re: Should the BFR have a launch escape system?
« Reply #84 on: 10/07/2017 05:34 PM »
I' with Robotbeat here: it's possible that rockets fundamentally cannot reach modern aircrafts levels of safety, but I fail to see how they couldn't reach acceptable reliability for routine commercial operations.

Those two things are in direct conflict.

Aircraft are required to be as safe as they are by entities like the FAA.  Why would they allow a far less safe vehicle to be in "routine commercial operations" when they don't for airliners?
Because this isn't an airliner. Regulations can change. FAA already was planning to allow routine commercial operations for space tourism.
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Re: Should the BFR have a launch escape system?
« Reply #85 on: 10/07/2017 05:39 PM »
Meh, I disagree with your whole shpiel. A lot of people died in the 1950s in aircraft. But people still flew, and if SpaceX gets to that reliability level, they'll be fine even for point to point due to lifetime saved in getting to destination faster.

People are treating LAS as if it's magic and saves you in all instances. It ain't magic. It'll fail to save you 1 time out of 10, and that's just on the way up. And such systems can kill you all by themselves even if the rocket is fine: http://www.dailymail.co.uk/news/article-2548135/Coroner-slams-ejector-seat-manufacturer-failing-warn-RAF-defects-led-death-Red-Arrows-pilot.html

A LASless BFR that has flown and been recovered 2000 times safely is a lot safer than Orion or Soyuz will ever be.

What you just said is that this rocket is going to be at least 100 times safer than any rocket before it, but that any LAS the same company builds won't be any safer than historical LAS's.

Makes zero sense.
Sure it makes sense. LASes (and similar things like ejection seats) are never tested as often as launches are. By their very nature they are often destructive and not amenable to reuse. The whole reason BFR might get 100 times as safe is not because SpaceX is magic but because they can afford to fly it a thousand times to prove it's safe.

You have a choice. Spend resources on a LAS, which would halve the number of people you can carry while also G costing billions to develop, or you focus on safety of the vehicle and getting costs down and flight rate up enough to become safer WITHOUT a LAS than existing systems WITH a LAS.
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Offline TomH

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Re: Should the ITS have a launch escape system?
« Reply #86 on: 10/07/2017 07:36 PM »
There are a list of reasons to conclude this design can at least be safer than the shuttle by a significant margin.

Also, unlike the shuttle, it looks to me like we will have a good long time (or many launches) to establish the safety of the BFS architecture before committing to manned launches.

As to it's ultimate safety, I know nobody knows.. but we can know we will know before we need to know :-)

And add to that the fact  that BFR/BFS will function far more as a traditional rocket than STS. STS had some fatal design flaws, each of which led to LOV/LOC.
-Massive segmented solid boosters
-A fragile, TPS sitting downhill from falling ice and brittle foam.

Obviously, new technology comes with unknown risks. At the same time, basic rocket engineering has now had 80 years to mature. CAD troubleshooting and 3D printing were not available in the past. This rocket will have no COPVs, no LH2, none of STS's fatal flaws. So from the starting line, this rocket will begin its engineering design with a lot of advantages not available in the past. Just as a new car design today would assume crumple zones, impact absorbing composites, seat belts, air bags, radar detection/avoidance, ABS, telescoping steering collumns, etc., BFR starts off with innumerable lessons from history already built in. How many original Atlas rockets failed? How many Atlas V have failed? You learn from mistakes on past rockets and apply those lessons to new rockets.

Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #87 on: 10/07/2017 08:15 PM »
Interestingly, Shuttle only managed like 8 or 9 launches per year at its peak, whereas SpaceX has already down 13 this year and hopes to get to a total of 20 plus another 30 next year. And it looks likely they'll get close to those numbers.

Since BFR is primarily just a replacement for Falcon in the early days, that means it will be entering into a demand position much better than Shuttle.
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Offline Lee Jay

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Re: Should the BFR have a launch escape system?
« Reply #88 on: 10/08/2017 12:10 AM »
I' with Robotbeat here: it's possible that rockets fundamentally cannot reach modern aircrafts levels of safety, but I fail to see how they couldn't reach acceptable reliability for routine commercial operations.

Those two things are in direct conflict.

Aircraft are required to be as safe as they are by entities like the FAA.  Why would they allow a far less safe vehicle to be in "routine commercial operations" when they don't for airliners?
Because this isn't an airliner. Regulations can change. FAA already was planning to allow routine commercial operations for space tourism.

Taking 6 people paying a quarter million each to space for a couple minutes on a sub-orbital mission, all of them likely having signed a massive waiver isn't the same thing at all as commercial, economy-fare point-to-point travel of thousands of average folks each day.

This idea of using this vehicle for rapid, volume, point-to-point travel of average people paying airline economy fares is about as far fetched as FTL and propellantless propulsion.  It will be thousands of times less safe than the average airliner.

The Concorde was the safest airliner in the world until one crash.  That one made it the least safe (and by a wide margin - the 707 was five times safer).  This is because of its low flight rate.  1 crash in about 50,000 flights is a terrible record for an airliner.  1 crash in 100 flights is world-class for rockets.  The fatal accident rate for airliners over the past 10 years is about 1 in 4 million, including the entire world.  For just the US and Canada, it's better than 1 in 10 million.

So, how do you expect SpaceX to get from 1 in 100 (world class for rockets) to 1 in 10,000,000 - a five order of magnitude improvement?  Or do you expect average folks to accept an accident rate that's thousands of times worse than an airliner?

Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #89 on: 10/08/2017 12:23 AM »
So you're saying people shouldn't be allowed to take measures risks?

Should we go back in time and stop people from taking airline flights in the 50s just because they don't meet current airline standards?

I say if the FAA is doing their job, they'll make sure people understand the risks involved, take reasonable steps that ensure as much safety as possible without making it out of reach of normal people, and then just let people take those risks.

We don't ban people from riding motorcycles even though it's very unsafe.
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Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #90 on: 10/08/2017 12:28 AM »
If SpaceX gets reliability to just 99.995% reliability, they will be superior to regular airlines in average lifetime saved. Saving 12 hours of your useful life is worth it at that point.
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Offline cppetrie

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Re: Should the BFR have a launch escape system?
« Reply #91 on: 10/08/2017 12:29 AM »
People do risky things literally on a daily basis by driving to work. It doesnít need to demonstrate equal risk to airliners, just sufficiently low risk to warrant not sitting on a plane for 18 hours, where you have a not insignificant chance of suffering a DVT that could result in death, and instead fly by rocket and be where youíre going in a couple hours instead (couple hours includes transport from dock to launch platform and back).

Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #92 on: 10/08/2017 12:47 AM »
I don't think we should get rid of regular airlines. People should still be allowed to take them, obviously.

And by the way: Concorde still flew paying passengers for years after the accident. That means you don't have to achieve a safety record equal to today's airlines to be allowed to fly passengers. Bush pilots in Alaska fly passengers all the time and the general aviation crash rate is very high.

If you drive in a car the same distance as BFR would travel on a long distance trip, you have about a 0.01% chance of dying. In my opinion, that's a pretty reasonable standard, equal to 99.99% reliability. Do we outlaw driving (or taking a bus or train) cross-country just because flying in a jet is safer? Obviously not.

And yeah, I think it's pretty reasonable for BFR to achieve 99.99% reliability long-term, provided it can get anywhere near the cost figure it's shooting for. And I think that's a reasonable level for the FAA to require for mass long distance transit. More waivers required before that level is achieved.

Higher reliability can come later.
« Last Edit: 10/08/2017 12:48 AM by Robotbeat »
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Offline TomH

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Re: Should the BFR have a launch escape system?
« Reply #93 on: 10/08/2017 03:19 AM »
Perhaps we should examine a different metric. Maybe we should examine the total human miles flown on all US space craft flights and divide that by 14 to determine the average number of miles traveled per fatality. Then compare that to the number of miles traveled per fatality in cars.

Offline Lee Jay

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Re: Should the BFR have a launch escape system?
« Reply #94 on: 10/08/2017 03:46 AM »
And yeah, I think it's pretty reasonable for BFR to achieve 99.99% reliability long-term, provided it can get anywhere near the cost figure it's shooting for.

Sure...only 500 times better than F9 with 10 times the complexity.

Offline CuddlyRocket

Re: Should the BFR have a launch escape system?
« Reply #95 on: 10/08/2017 03:57 AM »
Aircraft are required to be as safe as they are by entities like the FAA.  Why would they allow a far less safe vehicle to be in "routine commercial operations" when they don't for airliners?

The FAA and other regulators don't set safety standards for airliners based on some theoretical assessment; they base them on the fact that they already know airliners can be built to meet such standards. If they couldn't then the safety standards would be lower, as they were in the past. (And 'can be built' also includes 'can be built at a price that enables economic operation'.)

Not all aircraft in routine commercial operations have to meet the same safety standards as airliners. In fact, safety standards for airliners varies with size. Then there are aircraft like helicopters, which are allowed to operate because they can do things and go places airliners cannot.

In short, the FAA is highly unlikely to impose safety standards on rocket powered passenger craft so onerous that they couldn't operate at all. Much more likely is that they'll impose safety standards that they know such craft can meet.

Offline Hog

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Re: Should the BFR have a launch escape system?
« Reply #96 on: 10/08/2017 04:29 PM »
Perhaps we should examine a different metric. Maybe we should examine the total human miles flown on all US space craft flights and divide that by 14 to determine the average number of miles traveled per fatality. Then compare that to the number of miles traveled per fatality in cars.
What if Columbia or Challenger were carrying the proposed Shuttle Passenger Module?  The Rockwell proposed SPM would carry 78 humans.
Compare this to another launch system that utilizes 3 crewmembers/launch that fails 20 times. It would appear to be safer based on the metric you propose.(assuming the same travelled distance for each system).

A system where 85 humans perish in 2 out of 135 missions is "safer" than another system where 60 perish, in 20 out of 135 missions, even though the total deaths in the latter system were less.
« Last Edit: 10/08/2017 04:36 PM by Hog »
Paul

Offline pathfinder_01

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Re: Should the BFR have a launch escape system?
« Reply #97 on: 10/08/2017 08:43 PM »
I think that for any near term realistic manned mission the BFR  should have a LES or the crew be launched in a system that does. While it isn't practical to have a LES and launch hundreds of people. I don't think that near term this thing will  be sending hundreds anywhere. The most likely first users of the system will be Space X test pilots and NASA astronauts.

I can not imagine NASA(a source of funding) allowing it's crews to use a system without a LES nor can I imagine a need to send hundreds anywhere in the solar system developing for just a bit of time.

Offline Norm38

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Re: Should the BFR have a launch escape system?
« Reply #98 on: 10/08/2017 09:08 PM »
Or do you expect average folks to accept an accident rate that's thousands of times worse than an airliner?

If they want to get to Mars in their lifetime they absolutely will accept more risk than an airline. Or they don't go. Those are the options.
There will not be a shortage of willing colonists. And if NASA stays home, so what?

Offline rklaehn

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Re: Should the BFR have a launch escape system?
« Reply #99 on: 10/08/2017 09:34 PM »
I don't think BFS should have a LES.

First of all, it does not need to be as reliable as a commercial airliner. A business traveller flies commercial airliners dozens of times per year, hundreds of times in a lifetime. A typical BFS passenger flying to mars would launch exactly once.

So even if it is a factor 10 less reliable than commercial airliners, it would still be acceptable for most people. The chances of dying during launch would still be much lower than the chances of dying during the 20 years of business travel while you make the money for the ticket...  :)

Second, BFS passengers bound for mars engage in other risky activities after the launch. So as long as the risk of launch is significantly lower than the other risks of the voyage to mars, minimising launch risk by reducing the capabilities of the vehicle might even be a net increase in risk for the entire voyage.

Imagine you have a LES that significantly reduces the launch capability, and because of it you have less redundancy or fewer spares for your life support system, less margin in your heat shield, etc.

Now of course somebody will argue that you could just reduce the number of passengers by half, and thus double the price. But if the price is too high, the entire mars settlement project does not work since there are not enough people willing and able to go.

By the way: I am sure there are some metrics such as risk per passenger mile where a mars-bound BFS could easily be vastly safer than a commercial airliner doing short trips.
Try the ISS 3D visualization at http://www.heavens-above.com/ISS_3D.aspx

Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #100 on: 10/08/2017 10:17 PM »
And yeah, I think it's pretty reasonable for BFR to achieve 99.99% reliability long-term, provided it can get anywhere near the cost figure it's shooting for.

Sure...only 500 times better than F9 with 10 times the complexity.
Yes, because I expect BFR to fly >500x as many times as Falcon 9.

And by reasonable, I meant that it'd be reasonable for the FAA to give that kind of requirement before putting passengers on for point to point.

For spaceflight, the bar should be lower, more like 99.5-99.9%, as that's comparable to a regular rocket (95-99%) with a LAS (catches at most one out of ten rocket failures).
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Offline Oli

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Re: Should the BFR have a launch escape system?
« Reply #101 on: 10/08/2017 10:35 PM »
And yeah, I think it's pretty reasonable for BFR to achieve 99.99% reliability long-term, provided it can get anywhere near the cost figure it's shooting for.

Sure...only 500 times better than F9 with 10 times the complexity.
Yes, because I expect BFR to fly >500x as many times as Falcon 9.

You're talking about ~10k flights per year, how should that happen if BFR doesn't prove to be extremely reliable and cheap beforehand?

« Last Edit: 10/08/2017 10:35 PM by Oli »

Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #102 on: 10/09/2017 04:49 AM »
And yeah, I think it's pretty reasonable for BFR to achieve 99.99% reliability long-term, provided it can get anywhere near the cost figure it's shooting for.

Sure...only 500 times better than F9 with 10 times the complexity.
Yes, because I expect BFR to fly >500x as many times as Falcon 9.

You're talking about ~10k flights per year, how should that happen if BFR doesn't prove to be extremely reliable and cheap beforehand?
I expect it to do so. More like 1000 per year for many years.


But really: I shouldn't say "expect." What I'm describing is what I think is the best possible outcome that could still happen. I don't really expect it to be that good.
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Offline intrepidpursuit

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Re: Should the BFR have a launch escape system?
« Reply #103 on: 10/10/2017 05:20 AM »
There are really two cases here. Risk of LOC (LOP loss of passengers?) on a mission to Mars, a planet 34 million miles away that we could never reach otherwise, and a LOP on a "mission" from LA to Shanghai that could have been done on a plane if you are the type of person who can be patient and kind for 18 hours straight.

For the mission to mars, comparison to Shuttle or upcoming CC vehicles is apt. Shuttle had the main engines attached to the crew compartment, so at the design table traditional abort would have been kind of pointless. It did turn out to lose crew because of its various required appendages and just one close call from its own engines. The BFR will fly many times with the human rated propulsion system before humans ever get on. At least a dozen and maybe 100 launches of the propulsion system before we put people on it. A simple propulsion system (single fuel type, autogenous pressurization, all throttleable and testable engines, no dangly bits) abort modes after the first minute or so of flight, thorough testing, lot of redundancies and engineering led launch team I think can get BFR to Dragon 2 levels of reliability and beyond even without a LES. 1 failure in 370 launches wouldn't put people on that launch.

For a mission to save a business day, the rules are different. Airplanes are scary but are safer than cars. There are hundreds of people on every single flight and it would fly at least hundreds of times a year. The level of safety necessary here is WAY higher. I don't think SpaceX could market this a general transportation until they found some way to make its safety comparable to planes. Whether I would do it or not, regulators would not let a company make money on a system that sacrifices lives for time. Of course, this problem wouldn't actually be solved by a LES, which only helps and does not solve the safety problem.

From a higher level perspective, if a BFS fails after the first few launches, they will probably have a hard time getting buy in. If the operators of the Hindenburg 2 started handing out parachutes for the next flights people still wouldn't get on the thing. This is a spacecraft that will be more valuable than its payloads. It really needs to not blow up; LES or not.

Offline Patchouli

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Re: Should the BFR have a launch escape system?
« Reply #104 on: 10/10/2017 06:09 AM »
Near term BFR probably should have a LAS of sorts though if the spaceship is upgraded to have more then a 1 to 1 thrust to weight ratio without shredding the vacuum engine nozzles and the ability to dump propellant you'd gain much of the benefits of having one except for a scenario where there's a catastrophic failure of the booster on the pad or early in flight.
It might be possible to design the nose of it to be able to detach and survive reentry but this would eat up a lot of mass probably reducing the payload by a third.
I  wonder would having several escape pods based on Dragon's be the way to go on early versions.
As for talks of it flying thousands of times per year and competing directly with airliners I dismiss this as mostly fantasy with the first version of BFR as it's air frame and engines are much higher stressed than an airliner so they will be subject to more wear and tear and need more frequent inspection.

« Last Edit: 10/10/2017 06:44 AM by Patchouli »

Offline JamesH65

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Re: Should the BFR have a launch escape system?
« Reply #105 on: 10/10/2017 09:57 AM »
Loads of people saying it should have a LAS, but no suggestions on how it could actually be done? Presumably because no-one has yet thought of a way of doing it? Is it even physically possible? All very well saying it should have one, but if having one means the craft never gets made because its either impossible or so hugely expensive, or make the craft useless for its intended purpose, then making it s a requirement is pointless.

Musk has said it won't have one. I guess he may have thought it through.

Online KelvinZero

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Re: Should the BFR have a launch escape system?
« Reply #106 on: 10/10/2017 10:48 AM »
Loads of people saying it should have a LAS, but no suggestions on how it could actually be done? Presumably because no-one has yet thought of a way of doing it? Is it even physically possible? All very well saying it should have one, but if having one means the craft never gets made because its either impossible or so hugely expensive, or make the craft useless for its intended purpose, then making it s a requirement is pointless.

Musk has said it won't have one. I guess he may have thought it through.
This thread has been specifically separated off from the thread discussing how it could be done, because that was being continually derailed by people posting on the thread who only wanted to say the thread was a dumb idea. :)

http://forum.nasaspaceflight.com/index.php?topic=43923.0

Offline guckyfan

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Re: Should the BFR have a launch escape system?
« Reply #107 on: 10/10/2017 10:56 AM »
Musk has said it won't have one. I guess he may have thought it through.

I guess he completely goes for reliability of the system. It has to be extremely reliable to work for a very large number of reuses. So he puts engineering for reliablity ahead of a LAS.

I can only think of one reasonable way to have a LAS for the whole crew of 100. Carrying a LAS all the way to Mars is not an option IMO, too much of a weight penalty. So have a separate vehicle, probably a tanker with a capsule on top that crams in 100 people and has its own abort propulsion. That tanker may lose up to 100t of propellant capacity but it would be enough to top off the tanks and bring the passengers. Maybe another launch but launches are cheap. That way the ship can be mostly fueled before passengers arrive.

Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #108 on: 10/10/2017 11:49 AM »
Seems everyone's assuming a LAS is free.

Giving BFS a LAS would cost billions of dollars and would dramatically reduce the payload in crewed configuration. Better to put those resources to use in improving reliability and a proven flightrate.
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Online KelvinZero

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Re: Should the BFR have a launch escape system?
« Reply #109 on: 10/10/2017 02:32 PM »
Pulled in from another thread, discussing BFS+Dragon2
In the medium term a Dragon has no place in a BFS architecture. It means carrying a vehicle with plenty of hypergolic propellant. If they want a mobile pod for local actions they would build one based on the BFS RCS-thrusters, maybe a smaller version. It runs on methalox and can be refueled from the BFS main tanks. A Dragon would not be a good match. Such a vehicle needs an airlock. Dragon is designed around the ability to reenter. It has a quite small internal volume due to the cone shape.
I think a dragon, for LAS plus other possible purposes, does have a place in the BFS architecture, in short, medium, and long terms.

Short term:
I think the first BFS produced will be a cargo version. I have heard that the Crew version will be a lot more expensive. Also it may not be allowed near NASA assets for various reasons. I can think of various scenarios where a Dragon on top of and external to a Cargo BFS, instead of continuing with F9, might be considered.

Medium term:
I define medium term as after the Cargo BFS has matured, and the final decisions on the Crew version, based on lessons from the cargo version, must be made. Musk has stated a clear plan for the Crew BFS but I believe that he will prepare for lessons or mistakes from the Cargo BFS to change that plan. He may really want for a Crew version yet not have achieved the safety margins he had hoped for.. yet.

Long term:
Long term I think there is a good reason for a third variant (the debate is simply how significant a variant it must be.. maybe it will end up a trivial modification of the Crew variant. That third variant is *Space Shuttle on steroids variant.* It is quite different from the Crew ( *passengers as cargo* ) variant. Like the shuttle it has a small team actually there to do work and  a large cargo bay with large doors that could take entire satellites on board.

I think a Dragon 2 could give you 100x more safety for many missions, because it is not just a LAS, it duplicates practically everything that you need to survive a trip to space and back. If you think you do not need a 100x more safety, perhaps you should turn that around and ask if you can be doing missions a hundred times more extreme for the same safety.

Asteroid missions could be a good example. Unlike passengers to Mars, you will not have people or even cargo waiting for you. They also do create specific new threats to your heatshield so there is very good reason to want a backup option for that too.

Online KelvinZero

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Re: Should the BFR have a launch escape system?
« Reply #110 on: 10/10/2017 10:09 PM »
In the medium term a Dragon has no place in a BFS architecture. It means carrying a vehicle with plenty of hypergolic propellant.
Please have that conversation here instead: https://forum.nasaspaceflight.com/index.php?topic=43438.0

...in fact I will quote it there and reply to it there now.

Why there? I am in no way talking about a LES-system but my understanding was that Dragon could become a utility vehicle around BFS. I argued that Dragon is not good for that purpose.
Because you said "In the medium term a Dragon has no place in a BFS architecture. It means carrying a vehicle with plenty of hypergolic propellant."

Therefore your argument is based on dismissing the worth of the BFS having a dragon for a LAS+lifeboat. Obviously the only reason to consider including a heatshield and massive superdraco engines is because these uses are considered as part of the worth of including a crew dragon.

Offline guckyfan

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Re: Should the BFR have a launch escape system?
« Reply #111 on: 10/11/2017 07:35 AM »
I emphasized that this vehicle is not a LES system but a utility vehicle. My understanding was that this is what was talked about. A Dragon is a poor match for that purpose.

Offline Lobo

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Re: Should the BFR have a launch escape system?
« Reply #112 on: 10/11/2017 11:33 PM »
Musk has said it won't have one. I guess he may have thought it through.

I guess he completely goes for reliability of the system. It has to be extremely reliable to work for a very large number of reuses. So he puts engineering for reliablity ahead of a LAS.

I can only think of one reasonable way to have a LAS for the whole crew of 100. Carrying a LAS all the way to Mars is not an option IMO, too much of a weight penalty. So have a separate vehicle, probably a tanker with a capsule on top that crams in 100 people and has its own abort propulsion. That tanker may lose up to 100t of propellant capacity but it would be enough to top off the tanks and bring the passengers. Maybe another launch but launches are cheap. That way the ship can be mostly fueled before passengers arrive.

Back when I was working with the design team that was working on concepts of what the Mars Transportation System might look like, before Musk unveiled the ITS system a year ago, the issue of an LAS was debated.  We eventually came up with a biconic design as well as a Super Dragon Capsule type of design that sat on a reusable 2nd stage.
The Super Dragon Capsule design was easier to put an LAS on, as it sat on a 2nd stage and was launch unfueled.  So it only had enough propellant for abort, and then would be refueled in orbit.  But it had other drawbacks like door in the heat shield for the engines, as well as both pressure fed fast fire abort engines and pump fed normal propulsion engines.  And it was 3 pieces instead of just 2 like the biconic concept.

I'd always favored a 2-piece biconic design overall for simplicity and capability, and eventually I won out with that in the team.  But the rest of the team still thought it would have an LAS, so we worked one into it.  But I still never thought SpaceX's design would have one.  And that has turned out to be correct. 
The main reasons are there's a lot of design compromises.  The ship is already going to be very complex without introducing more failure modes and complexity into it.  While an LAS would help with launch, it becomes a liability in cost and capacity, and even an extra point of failure after that, with no real benefits.

The way I saw it, early on, the crews would be small.  Probably no more than 7, which Dragon 2 could take up as it would already be flying and available to do so, and it has an LAS.  If you wanted 14, you could do two Dragon 2 launches for the crew.  With reusable boosters and spacecraft, that's really not that prohibitive.  After that, BFR should have established a flight track record.  As it would have redundant engines, and tolerate an engine out at any point during launch, that really reduces the failure modes for a liquid rocket.  There could still be a complete explosion on the pad or lift off, which would result in the loss of crew, but barring that, it should be able to tolerate most other issues with a safe abort mode.

But even so, if the customer still demand an LAS system, a modified ship could be built that would have an LAS, and be used as a crew taxi to take a full crew of 100 up just before departure from orbit.  It would sacrifice it's payload for that LAS system but it would be just a reusable crew taxi, and that would be it's only job.  If an LAS was a must, then that was the way to do it rather than to try to integrate it into the interplanetary ship.  It'll already have enough jobs that it must do.
But...it will be a long time before the crews would be anywhere near that big.  You need to have a lot of infrastructure on the Moon or Mars to support adding 100 new people on a single mission, so that's a long time down the road, and Falcon/Dragon can handle the smaller crews in the mean time.





Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #113 on: 10/12/2017 01:44 PM »
By the way, a LAS would add its own risk factors. For instance, if the LAS on Orion fails to separate, the crew dies.
And commercial airlines are so safe that if you added a LAS or ejection seats to them, the extra risks would greatly outweigh the abort advantages, and you'd REDUCE overall safety.

Again, for those in the back:
If BFR is as reliable as Musk wants it to be, adding a LAS would REDUCE safety.
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Online AncientU

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Re: Should the BFR have a launch escape system?
« Reply #114 on: 10/12/2017 04:26 PM »
I can't believe that someone is building a NOVA-class, fully reusable launcher and all this focus on a friggin' launch escape system.
Get over it...
« Last Edit: 10/12/2017 04:27 PM by AncientU »
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Online Semmel

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Re: Should the BFR have a launch escape system?
« Reply #115 on: 10/12/2017 04:47 PM »
Robotbeat, I agree with you. However the question is not based purely on statistics but also on human nature. If you have a LOC event, it's a big difference in public opinion if it reads "despite the LAS, the failure was so severe that no one survived." or "no one survived and the rocket didn't even have an ejection seat.". At this point it does not matter if a LAS would have caused the failure and didn't save the crew. In the mind of the public, a LAS makes you seem to try harder even if the engineering said otherwise. As an engineer, it huts me to say this but here are some examples..

In the US, many more people are scared of terrorism than car crashes, despite the fact that it is far more likely to die in a car than by a terrorist attack. And there are no anti car laws put in place. Jet we see legislation after legislation giving advanced rights to the police to counter the terrorist threat. That is just an example of how nonsensical public perception can be. And the same will happen to a BFR with or without a LAS. This can mean life and death of SpaceX.

Also, I am not arguing in favor of a LAS here. I share your concern that a LAS can make BFR less safe. But I want to point out that we can't restrict the discussion on the engineering aspects.

Offline Norm38

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Re: Should the BFR have a launch escape system?
« Reply #116 on: 10/12/2017 06:49 PM »
A big difference in human nature deals with private vs. public spending.  When astronauts are government employees and national heroes and they are killed in an accident, every citizen feels they are a stakeholder, that it was their money being spent, and why oh why wasn't more done.

Change that over to the same number of people killed while flying an experimental aircraft on their dime, and the public shrugs it off. People are allowed to risk their lives with their money.
We need to get to commercial operations where people who accept the risks are buying their own tickets.  At that point governments will put their crew on it, just like government employees fly commercial and don't all fly in military transports strapped into ejection seats.

Airliners like TWA 800 have exploded with great loss of life, far more than 14 people.  And no one asked why 747s don't have escape capsules, and Boeing hasn't redesigned the 747 to add them.  Passengers still fly, because there's no other way to get to their destination. If people want to go to Mars, they will accept the risks that come with the trip.

The only way that we are going to get to airliner level operations and reliability is to simply just do it that way.

Online Semmel

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Re: Should the BFR have a launch escape system?
« Reply #117 on: 10/12/2017 07:11 PM »
I dont want to defend how the public opinion often works. I find it quite nonsensical my self. But look how the reaction was to the first Tesla autopilot death. It got way more attention than it should have. Way more than any other car accident got. Now imagine this wasnt a self driving car with a guy not paying attention where he should have, but maybe one of the first BFR point to point flights. I dont think my self that accidents should be a deciding factor. But public opinion should at least go into the equation. I agree, it should not dominate it.

Online KelvinZero

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Re: Should the BFR have a launch escape system?
« Reply #118 on: 10/12/2017 10:02 PM »
By the way, a LAS would add its own risk factors. For instance, if the LAS on Orion fails to separate, the crew dies.
And commercial airlines are so safe that if you added a LAS or ejection seats to them, the extra risks would greatly outweigh the abort advantages, and you'd REDUCE overall safety.

Again, for those in the back:
If BFR is as reliable as Musk wants it to be, adding a LAS would REDUCE safety.
Do you have a reference for that? I assumed it was cost, but I can imagine it being true.

Offline yg1968

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Re: Should the ITS have a launch escape system?
« Reply #119 on: 10/12/2017 11:47 PM »
Its LES is pretty much the engines on the bottom of the ship, you can't have an escape system that large.

It's similar to the crewed Dream Chaser's abort system.
« Last Edit: 10/12/2017 11:53 PM by yg1968 »

Offline Lars-J

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Re: Should the ITS have a launch escape system?
« Reply #120 on: 10/13/2017 04:55 AM »
Its LES is pretty much the engines on the bottom of the ship, you can't have an escape system that large.

It's similar to the crewed Dream Chaser's abort system.

...Which they were having problems with, even at Dreamchasers much smaller scale. When DC was dropped from commercial crew, they were in the middle of evaluating new propulsion ideas to replace it. (It was a hybrid system) The cargo DC has no such system.
« Last Edit: 10/13/2017 04:55 AM by Lars-J »

Offline pathfinder_01

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Re: Should the BFR have a launch escape system?
« Reply #121 on: 10/13/2017 09:03 AM »
By the way, a LAS would add its own risk factors. For instance, if the LAS on Orion fails to separate, the crew dies.
And commercial airlines are so safe that if you added a LAS or ejection seats to them, the extra risks would greatly outweigh the abort advantages, and you'd REDUCE overall safety.

Again, for those in the back:
If BFR is as reliable as Musk wants it to be, adding a LAS would REDUCE safety.

Ejection seats are not practical on any commercial airline because of the wide variation between passengers(300 pound man, baby, elderly woman), number of passengers on a plane(hundreds) and the fact that the passengers would need training. Nobody would think of designing an experimental craft , bomber or a fighter jet without some consideration of escape.

In this time period and age BFR is closer to an experimental aircraft than anything else and If the shuttle had lived up to it's safety claims Columbia and Challenger would not have occurred.


The first BFR flights will not  have such a number of people that it is impossible to put in an LES. In fact I don't think you could find as many people as Elon hopes to travel to the moon, mars or LEO at the price he is offering on any regular bias. The most likely paying passenger at the moment for better or worse is going to be NASA and not private citizens.

Offline JamesH65

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Re: Should the BFR have a launch escape system?
« Reply #122 on: 10/13/2017 10:42 AM »
By the way, a LAS would add its own risk factors. For instance, if the LAS on Orion fails to separate, the crew dies.
And commercial airlines are so safe that if you added a LAS or ejection seats to them, the extra risks would greatly outweigh the abort advantages, and you'd REDUCE overall safety.

Again, for those in the back:
If BFR is as reliable as Musk wants it to be, adding a LAS would REDUCE safety.

Ejection seats are not practical on any commercial airline because of the wide variation between passengers(300 pound man, baby, elderly woman), number of passengers on a plane(hundreds) and the fact that the passengers would need training. Nobody would think of designing an experimental craft , bomber or a fighter jet without some consideration of escape.

In this time period and age BFR is closer to an experimental aircraft than anything else and If the shuttle had lived up to it's safety claims Columbia and Challenger would not have occurred.


The first BFR flights will not  have such a number of people that it is impossible to put in an LES. In fact I don't think you could find as many people as Elon hopes to travel to the moon, mars or LEO at the price he is offering on any regular bias. The most likely paying passenger at the moment for better or worse is going to be NASA and not private citizens.

Mitigated by the thought that the BFS/R will spend a considerable proportion of its experimental period being flown by computers with no-one on board.

Offline yg1968

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Re: Should the ITS have a launch escape system?
« Reply #123 on: 10/13/2017 02:33 PM »
Its LES is pretty much the engines on the bottom of the ship, you can't have an escape system that large.

It's similar to the crewed Dream Chaser's abort system.

...Which they were having problems with, even at Dreamchasers much smaller scale. When DC was dropped from commercial crew, they were in the middle of evaluating new propulsion ideas to replace it. (It was a hybrid system) The cargo DC has no such system.

I was under the impression that it was the hybrid motor which was problematic, not the LAS. The acquisition of Orbitec gave them better options for propulsion.

Offline envy887

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Re: Should the BFR have a launch escape system?
« Reply #124 on: 10/13/2017 04:00 PM »
...
The first BFR flights will not  have such a number of people that it is impossible to put in an LES. In fact I don't think you could find as many people as Elon hopes to travel to the moon, mars or LEO at the price he is offering on any regular bias. The most likely paying passenger at the moment for better or worse is going to be NASA and not private citizens.

If there are so few passengers, then they can launch and return on F9R/Dragon 2 until BFR completes hundreds of successful flights.

Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #125 on: 10/13/2017 11:07 PM »
...
The first BFR flights will not  have such a number of people that it is impossible to put in an LES. In fact I don't think you could find as many people as Elon hopes to travel to the moon, mars or LEO at the price he is offering on any regular bias. The most likely paying passenger at the moment for better or worse is going to be NASA and not private citizens.

If there are so few passengers, then they can launch and return on F9R/Dragon 2 until BFR completes hundreds of successful flights.
Bingo. And how much does, say, 300 flights cost of SpaceX gets costs as low as they want? Just $600m, less than developing a LAS.
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Offline intrepidpursuit

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Re: Should the BFR have a launch escape system?
« Reply #126 on: 10/13/2017 11:15 PM »
...
The first BFR flights will not  have such a number of people that it is impossible to put in an LES. In fact I don't think you could find as many people as Elon hopes to travel to the moon, mars or LEO at the price he is offering on any regular bias. The most likely paying passenger at the moment for better or worse is going to be NASA and not private citizens.

If there are so few passengers, then they can launch and return on F9R/Dragon 2 until BFR completes hundreds of successful flights.
Bingo. And how much does, say, 300 flights cost of SpaceX gets costs as low as they want? Just $600m, less than developing a LAS.

The Dragon flights will still be very expensive. They will get lots of experience with the ship before they are ready to put people on it anyway, no need to kludge dragon in there.

Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #127 on: 10/13/2017 11:20 PM »
...
The first BFR flights will not  have such a number of people that it is impossible to put in an LES. In fact I don't think you could find as many people as Elon hopes to travel to the moon, mars or LEO at the price he is offering on any regular bias. The most likely paying passenger at the moment for better or worse is going to be NASA and not private citizens.

If there are so few passengers, then they can launch and return on F9R/Dragon 2 until BFR completes hundreds of successful flights.
Bingo. And how much does, say, 300 flights cost of SpaceX gets costs as low as they want? Just $600m, less than developing a LAS.

The Dragon flights will still be very expensive. They will get lots of experience with the ship before they are ready to put people on it anyway, no need to kludge dragon in there.
We weren't saying kludge a Dragon on there, we were saying launch the Dragon on F9 and transfer crew to the BFR, just like NASA was/is planning for Altair or the Mars transfer vehicle, then return to the Dragon for entry.
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Offline yg1968

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Re: Should the BFR have a launch escape system?
« Reply #128 on: 10/13/2017 11:26 PM »
...
The first BFR flights will not  have such a number of people that it is impossible to put in an LES. In fact I don't think you could find as many people as Elon hopes to travel to the moon, mars or LEO at the price he is offering on any regular bias. The most likely paying passenger at the moment for better or worse is going to be NASA and not private citizens.

If there are so few passengers, then they can launch and return on F9R/Dragon 2 until BFR completes hundreds of successful flights.
Bingo. And how much does, say, 300 flights cost of SpaceX gets costs as low as they want? Just $600m, less than developing a LAS.

The Dragon flights will still be very expensive. They will get lots of experience with the ship before they are ready to put people on it anyway, no need to kludge dragon in there.
We weren't saying kludge a Dragon on there, we were saying launch the Dragon on F9 and transfer crew to the BFR, just like NASA was/is planning for Altair or the Mars transfer vehicle, then return to the Dragon for entry.

The objective of BFR is to replace Dragon, Falcon 9 and FH. So it would be strange to have to rely on them.

Offline intrepidpursuit

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Re: Should the BFR have a launch escape system?
« Reply #129 on: 10/13/2017 11:28 PM »
...
The first BFR flights will not  have such a number of people that it is impossible to put in an LES. In fact I don't think you could find as many people as Elon hopes to travel to the moon, mars or LEO at the price he is offering on any regular bias. The most likely paying passenger at the moment for better or worse is going to be NASA and not private citizens.

If there are so few passengers, then they can launch and return on F9R/Dragon 2 until BFR completes hundreds of successful flights.
Bingo. And how much does, say, 300 flights cost of SpaceX gets costs as low as they want? Just $600m, less than developing a LAS.

The Dragon flights will still be very expensive. They will get lots of experience with the ship before they are ready to put people on it anyway, no need to kludge dragon in there.
We weren't saying kludge a Dragon on there, we were saying launch the Dragon on F9 and transfer crew to the BFR, just like NASA was/is planning for Altair or the Mars transfer vehicle, then return to the Dragon for entry.

The kludge is making it a part of the system, whether it is built into the rocket or not. It is impossible for BFR to be cheaper than Falcon 9 if you still have to launch a Falcon 9 (or several). They won't put people on BFR until they are comfortable launching them along with it.

Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #130 on: 10/13/2017 11:29 PM »
...
The first BFR flights will not  have such a number of people that it is impossible to put in an LES. In fact I don't think you could find as many people as Elon hopes to travel to the moon, mars or LEO at the price he is offering on any regular bias. The most likely paying passenger at the moment for better or worse is going to be NASA and not private citizens.

If there are so few passengers, then they can launch and return on F9R/Dragon 2 until BFR completes hundreds of successful flights.
Bingo. And how much does, say, 300 flights cost of SpaceX gets costs as low as they want? Just $600m, less than developing a LAS.

The Dragon flights will still be very expensive. They will get lots of experience with the ship before they are ready to put people on it anyway, no need to kludge dragon in there.
We weren't saying kludge a Dragon on there, we were saying launch the Dragon on F9 and transfer crew to the BFR, just like NASA was/is planning for Altair or the Mars transfer vehicle, then return to the Dragon for entry.

The objective of BFR is to replace Dragon, Falcon 9 and FH. So it would be strange to have to rely on them.
That's not at all the only objective of BFR. And if NASA insists on a LAS, then using the already-proven F9/Dragon combo would be much cheaper than adding one to BFR.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #131 on: 10/13/2017 11:37 PM »
...
The first BFR flights will not  have such a number of people that it is impossible to put in an LES. In fact I don't think you could find as many people as Elon hopes to travel to the moon, mars or LEO at the price he is offering on any regular bias. The most likely paying passenger at the moment for better or worse is going to be NASA and not private citizens.

If there are so few passengers, then they can launch and return on F9R/Dragon 2 until BFR completes hundreds of successful flights.
Bingo. And how much does, say, 300 flights cost of SpaceX gets costs as low as they want? Just $600m, less than developing a LAS.

The Dragon flights will still be very expensive. They will get lots of experience with the ship before they are ready to put people on it anyway, no need to kludge dragon in there.
We weren't saying kludge a Dragon on there, we were saying launch the Dragon on F9 and transfer crew to the BFR, just like NASA was/is planning for Altair or the Mars transfer vehicle, then return to the Dragon for entry.

The kludge is making it a part of the system, whether it is built into the rocket or not. It is impossible for BFR to be cheaper than Falcon 9 if you still have to launch a Falcon 9 (or several). They won't put people on BFR until they are comfortable launching them along with it.
The point of BFR isn't just to be cheaper than F9.

NASA has no way to get to Mars orbit, Mars surface, or Moon surface. BFR solves that. If for the first Mars trip, NASA insists on a LAS, then SpaceX will be happy to launch the crew on the reusable Falcon 9 and Dragon.

This really isn't that hard to understand.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline intrepidpursuit

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Re: Should the BFR have a launch escape system?
« Reply #132 on: 10/13/2017 11:40 PM »
If you are going to take BFR to the moon or mars then you are relying on it not to fail anyway. Adding in a Dragon, a Falcon 9, and two crew transfers isn't going to make the system appreciably safer.

NASA will either accept the BFR for human use or not. I don't see any helpful middle ground other than just using it for cargo only.

(keeps telling me the body is empty if I try reply with the quoted thread)

Offline Robotbeat

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Re: Should the BFR have a launch escape system?
« Reply #133 on: 10/13/2017 11:43 PM »
If you are going to take BFR to the moon or mars then you are relying on it not to fail anyway. Adding in a Dragon, a Falcon 9, and two crew transfers isn't going to make the system appreciably safer.

NASA will either accept the BFR for human use or not. I don't see any helpful middle ground other than just using it for cargo only.

(keeps telling me the body is empty if I try reply with the quoted thread)
Nope. NASA didn't put a LAS on Altair, but they insist on one for Orion. That contradicts your logic.
« Last Edit: 10/13/2017 11:44 PM by Robotbeat »
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Offline pathfinder_01

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Re: Should the BFR have a launch escape system?
« Reply #134 on: 10/14/2017 06:06 AM »
If you are going to take BFR to the moon or mars then you are relying on it not to fail anyway. Adding in a Dragon, a Falcon 9, and two crew transfers isn't going to make the system appreciably safer.

NASA will either accept the BFR for human use or not. I don't see any helpful middle ground other than just using it for cargo only.

(keeps telling me the body is empty if I try reply with the quoted thread)

In practice refueling on orbit with cryogens could be viewed as risky. It could be a good idea to use a dragon or specially adapted BFR(i.e. one with a LES) for a crew transfer after the BFR is fully fueled and checked out. ESP. if going to Mars(five refueling flights sounds like it could take a lot of time).

Also a Cargo BFR could be adapted to be crewed in space if it has a habitation or other module in the cargo bay with a docking port. This could be cheaper(and faster) than having to develop the crewed version and much more suitable to smaller crew sizes. It also plays well with other companies and organizations(i.e. Space X does not need to develop the payload).

That being said at the moment there is little value of a LES on the Moon or Mars(i.e. no one to rescue you should it go off) and a lot of dead weight to drag there.
« Last Edit: 10/14/2017 06:32 AM by pathfinder_01 »

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