Author Topic: ITS Development Updates and Discussion Thread  (Read 177672 times)

Online Robotbeat

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Re: ITS Development Updates and Discussion Thread
« Reply #880 on: 07/15/2017 04:27 PM »
Nobody but SpaceX is doing serious work on a Mars lander. That's the obvious role.

And that is the hardest part of ITS.

Erm...

NASA did a lot of serious work on Mars landers. And actually landed seven.
...none of which scales beyond a ton or so. Of course you know that. You also knew what I was referring to.

NASA HSF spends all their money on things other than the one thing needed for Moon or Mars: a lander.
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Offline Negan

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Re: ITS Development Updates and Discussion Thread
« Reply #881 on: 07/15/2017 05:07 PM »
Nobody but SpaceX is doing serious work on a Mars lander. That's the obvious role.

And that is the hardest part of ITS.

Erm...

NASA did a lot of serious work on Mars landers. And actually landed seven.
...none of which scales beyond a ton or so. Of course you know that. You also knew what I was referring to.

NASA HSF spends all their money on things other than the one thing needed for Moon or Mars: a lander.

I thought the reason why NASA was working on hypersonic inflatable aerodynamic decelerator technology as well as supporting the Red Dragon mission was to support heavier payloads.

Offline original_mds

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Re: ITS Development Updates and Discussion Thread
« Reply #882 on: 07/17/2017 06:19 PM »
I thought the reason why NASA was working on hypersonic inflatable aerodynamic decelerator technology as well as supporting the Red Dragon mission was to support heavier payloads.
Maybe.  But it also has implications for landing non-aerodynamic shapes and potential adaptation to an inflatable escape pod/(re)entry vehicle, similar to the MOOS concept.

Offline Ionmars

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Re: ITS Development Updates and Discussion Thread
« Reply #883 on: 07/18/2017 03:21 PM »
...
...
I thought the reason why NASA was working on hypersonic inflatable aerodynamic decelerator technology as well as supporting the Red Dragon mission was to support heavier payloads.
Heavier, yes. But when the lander is greater than 40 tonnes, HIAD will not do the job.  Other systems will be required, such as supersonic retropulsion and biconic shells.
https://solarsystem.nasa.gov/docs/IPPW-8_Short_Course_SRP_Edquist_Final.pdf
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Offline JasonAW3

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Re: ITS Development Updates and Discussion Thread
« Reply #884 on: 07/18/2017 03:41 PM »
...
...
I thought the reason why NASA was working on hypersonic inflatable aerodynamic decelerator technology as well as supporting the Red Dragon mission was to support heavier payloads.
Heavier, yes. But when the lander is greater than 40 tonnes, HIAD will not do the job.  Other systems will be required, such as supersonic retropulsion and biconic shells.
https://solarsystem.nasa.gov/docs/IPPW-8_Short_Course_SRP_Edquist_Final.pdf

I have to wonder if HIAD could help and by how much with deceleration.  If we're talking about 10% or less, it likely wouldn't really be worth the extra mass it would add.
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Offline Ictogan

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Re: ITS Development Updates and Discussion Thread
« Reply #885 on: 07/18/2017 03:45 PM »
...
...
I thought the reason why NASA was working on hypersonic inflatable aerodynamic decelerator technology as well as supporting the Red Dragon mission was to support heavier payloads.
Heavier, yes. But when the lander is greater than 40 tonnes, HIAD will not do the job.  Other systems will be required, such as supersonic retropulsion and biconic shells.
https://solarsystem.nasa.gov/docs/IPPW-8_Short_Course_SRP_Edquist_Final.pdf
40 tons is still a huge Mars lander compared to anything that has been landed there so far.

Offline RonM

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Re: ITS Development Updates and Discussion Thread
« Reply #886 on: 07/18/2017 04:13 PM »
...
...
I thought the reason why NASA was working on hypersonic inflatable aerodynamic decelerator technology as well as supporting the Red Dragon mission was to support heavier payloads.
Heavier, yes. But when the lander is greater than 40 tonnes, HIAD will not do the job.  Other systems will be required, such as supersonic retropulsion and biconic shells.
https://solarsystem.nasa.gov/docs/IPPW-8_Short_Course_SRP_Edquist_Final.pdf
40 tons is still a huge Mars lander compared to anything that has been landed there so far.

The NASA DRA 5.0 largest lander was 40 tons, so HIAD can handle what NASA was planning.

Offline ChrML

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Re: ITS Development Updates and Discussion Thread
« Reply #887 on: 07/18/2017 04:24 PM »
I'm sure that anyone volunteering for the first flights will be very well aware of the huge risks of the mission. I seriously doubt any launch abort system is planned for the first decade.


Even if it was, I'm not sure adding complexity is the best way of dealing with this. Complexity is a risk by itself, and could even be the cause of the catastrophic failure it was going to prevent.

I think the best way would be a more passive approach to increase survivability in the event of RUD. For example instead of a lunch system, you could design the capsule in a way that an engine/tank explosion would "shoot" the capsule out like a bullet from a gun. Requires reinforceing the walls below and the torpedo wall between. Then add chutes for the landing.

Online Robotbeat

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Re: ITS Development Updates and Discussion Thread
« Reply #888 on: 07/19/2017 02:31 AM »
...
...
I thought the reason why NASA was working on hypersonic inflatable aerodynamic decelerator technology as well as supporting the Red Dragon mission was to support heavier payloads.
Heavier, yes. But when the lander is greater than 40 tonnes, HIAD will not do the job.  Other systems will be required, such as supersonic retropulsion and biconic shells.
https://solarsystem.nasa.gov/docs/IPPW-8_Short_Course_SRP_Edquist_Final.pdf
40 tons is still a huge Mars lander compared to anything that has been landed there so far.

The NASA DRA 5.0 largest lander was 40 tons, so HIAD can handle what NASA was planning.
...but not alone. Many concepts propose also using SRP.

All of NASA's human lander designs now baseline SRP thanks to SpaceX.

The point is that none of those lander concepts are being seriously funded by NASA. HIAD is ultimately just a drag device, nothing even remotely close to a full lander.
« Last Edit: 07/19/2017 02:33 AM by Robotbeat »
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Offline Jim

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Re: ITS Development Updates and Discussion Thread
« Reply #889 on: 07/19/2017 02:48 AM »
I'm sure that anyone volunteering for the first flights will be very well aware of the huge risks of the mission. I seriously doubt any launch abort system is planned for the first decade.


Even if it was, I'm not sure adding complexity is the best way of dealing with this. Complexity is a risk by itself, and could even be the cause of the catastrophic failure it was going to prevent.

I think the best way would be a more passive approach to increase survivability in the event of RUD. For example instead of a lunch system, you could design the capsule in a way that an engine/tank explosion would "shoot" the capsule out like a bullet from a gun. Requires reinforceing the walls below and the torpedo wall between. Then add chutes for the landing.

That is not workable.

Online TomH

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Re: ITS Development Updates and Discussion Thread
« Reply #890 on: 07/19/2017 03:26 AM »
I think the best way would be a more passive approach to increase survivability in the event of RUD. For example instead of a lunch system, you could design the capsule in a way that an engine/tank explosion would "shoot" the capsule out like a bullet from a gun. Requires reinforceing the walls below and the torpedo wall between. Then add chutes for the landing.

This would require making the tank walls hundreds or even thousands of times thicker. The rocket would be many times heavier than the engines could lift from the ground.

Also, the hundreds to thousands of G-forces would pancake the capsule as well as the astronauts' bodies, killing them instantly.
« Last Edit: 07/19/2017 03:28 AM by TomH »

Offline RonM

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Re: ITS Development Updates and Discussion Thread
« Reply #891 on: 07/19/2017 04:05 AM »
...
...
I thought the reason why NASA was working on hypersonic inflatable aerodynamic decelerator technology as well as supporting the Red Dragon mission was to support heavier payloads.
Heavier, yes. But when the lander is greater than 40 tonnes, HIAD will not do the job.  Other systems will be required, such as supersonic retropulsion and biconic shells.
https://solarsystem.nasa.gov/docs/IPPW-8_Short_Course_SRP_Edquist_Final.pdf
40 tons is still a huge Mars lander compared to anything that has been landed there so far.

The NASA DRA 5.0 largest lander was 40 tons, so HIAD can handle what NASA was planning.
...but not alone. Many concepts propose also using SRP.

All of NASA's human lander designs now baseline SRP thanks to SpaceX.

The point is that none of those lander concepts are being seriously funded by NASA. HIAD is ultimately just a drag device, nothing even remotely close to a full lander.

Yes, SpaceX SRP is a better method. NASA isn't seriously working on any manned spaceflight other than SLS/Orion. No lunar or Mars landers at all. DSG could be useful, but it's just talk unless Congress funds it. That's a good reason to get back on topic. SpaceX is serious about ITS.

Online Robotbeat

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Re: ITS Development Updates and Discussion Thread
« Reply #892 on: 07/19/2017 05:06 AM »
Right. ITS is the only serious large Mars lander project in existence (a point which people disagreed with which is why we had that discussion about HIAD, which is just a drag device) and once Falcon 9 block 5 is finished, it should get a lot more serious.
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Offline ChrML

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Re: ITS Development Updates and Discussion Thread
« Reply #893 on: 07/19/2017 09:29 AM »
Quote from: TomH
This would require making the tank walls hundreds or even thousands of times thicker. The rocket would be many times heavier than the engines could lift from the ground.

Also, the hundreds to thousands of G-forces would pancake the capsule as well as the astronauts' bodies, killing them instantly.

Even if you design it weak at strategic places so that just 1% of the force pushes the craft up?

Offline envy887

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Re: ITS Development Updates and Discussion Thread
« Reply #894 on: 07/19/2017 01:05 PM »
Quote from: TomH
This would require making the tank walls hundreds or even thousands of times thicker. The rocket would be many times heavier than the engines could lift from the ground.

Also, the hundreds to thousands of G-forces would pancake the capsule as well as the astronauts' bodies, killing them instantly.

Even if you design it weak at strategic places so that just 1% of the force pushes the craft up?

You really don't wan't to use an uncontrolled explosion to move a spacecraft around. Not only would the spacecraft have to be reinforced against the worst case blast/penetration scenario (which means lots of mass), it has to be be able to be strong (and heavy) enough to take uncontrolled aerodynamic loads at high speeds in dense atmosphere.

For example, it wasn't the disintegrating external tank that destroyed Challenger. The loss of control authority resulted in excessive angle of attack, and then aerodynamic forces broke up the orbiter.

It's much better to use a propulsion system that has control over both acceleration and attitude for escape.

Offline jpo234

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Re: ITS Development Updates and Discussion Thread
« Reply #895 on: 07/19/2017 01:57 PM »
I think the best way would be a more passive approach to increase survivability in the event of RUD. For example instead of a lunch system, you could design the capsule in a way that an engine/tank explosion would "shoot" the capsule out like a bullet from a gun. Requires reinforceing the walls below and the torpedo wall between. Then add chutes for the landing.

Project Orion as a LAS  :o

« Last Edit: 07/19/2017 01:59 PM by jpo234 »

Online TomH

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Re: ITS Development Updates and Discussion Thread
« Reply #896 on: 07/19/2017 05:27 PM »
Quote from: TomH
This would require making the tank walls hundreds or even thousands of times thicker. The rocket would be many times heavier than the engines could lift from the ground.

Also, the hundreds to thousands of G-forces would pancake the capsule as well as the astronauts' bodies, killing them instantly.

Even if you design it weak at strategic places so that just 1% of the force pushes the craft up?

You really don't wan't to use an uncontrolled explosion to move a spacecraft around. Not only would the spacecraft have to be reinforced against the worst case blast/penetration scenario (which means lots of mass), it has to be be able to be strong (and heavy) enough to take uncontrolled aerodynamic loads at high speeds in dense atmosphere.

For example, it wasn't the disintegrating external tank that destroyed Challenger. The loss of control authority resulted in excessive angle of attack, and then aerodynamic forces broke up the orbiter.

It's much better to use a propulsion system that has control over both acceleration and attitude for escape.

This is correct. An engine on an X-15 once exploded during a static test. The rocket plane was bolted down and the total energy release was minuscule in contrast to what we are talking about here. The airframe was subjected to a 50 G surge which lasted probably less than a millisecond. The craft was severely damaged, although pilot Scott Crossfield, once again, miraculously was uninjured.

When a launch abort system pulls or pushes a capsule away from an explosion, the energy applied to acceleration is expended during several seconds rather than all in a millisecond. Think of it this way. You need to go to the store to grab something. The store is a mile away and your motorcycle is out of gas. As an alternative to putting more gas in the tank, you notice there is a 300' high crane next to your house with a 20,000 lb wrecking ball on the end. You arrange to have the wrecking ball swung such that it hits the motorcycle (with you on it) and simply knocks your bike (like an immense croquet mallet) flying through the air to land at the store. That's pretty much analogous to what you have proposed with the rocket.

Online Robotbeat

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Re: ITS Development Updates and Discussion Thread
« Reply #897 on: 07/22/2017 06:48 PM »
I vote a new update thread focusing explicitly on the 9m diameter BFR/BFS.




...

https://twitter.com/elonmusk/status/888813713800785923

Quote from: Elon Musk
A 9m diameter vehicle fits in our existing factories ...
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Offline DJPledger

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Re: ITS Development Updates and Discussion Thread
« Reply #898 on: 07/22/2017 07:51 PM »
Looks like 21 full size Raptors in 1+6+14 configuration will fit under a 9m dia. core. So basically IAC2016 ITS booster minus the outer ring of Raptors. Raptor thrust will have to be a bit lower than IAC2016 figure if new ITS booster has 21 Raptors to keep within 12Mlbf limit of LC-39A. We will have to wait until IAC2017 to find out how many Raptors the new smaller ITS booster will have.

Online vaporcobra

Re: ITS Development Updates and Discussion Thread
« Reply #899 on: 07/22/2017 08:06 PM »
I vote a new update thread focusing explicitly on the 9m diameter BFR/BFS.




...

https://twitter.com/elonmusk/status/888813713800785923

Quote from: Elon Musk
A 9m diameter vehicle fits in our existing factories ...

Agreed. New focused thread would be worthwhile. Before a mod actually creates one, I went ahead.

http://forum.nasaspaceflight.com/index.php?topic=43427.0
« Last Edit: 07/22/2017 08:11 PM by vaporcobra »

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