Author Topic: Should the BFR have a launch escape system?  (Read 11724 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 »

Online 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.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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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.   

Online 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.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

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.

Online 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.

Online 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 »

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