SpaceX: Advanced Launch Abort System (LAS)

[Crispy]

Oh indeed. I fully expect them to test and measure, I just don't expect them to find any issues. But they have to know for sure...

[ChefPat]

I wonder if the "nostrils" on the landing SD's could have some type of protective plug/cover that would pop off when they're fired for the landing maneuver?

[Crispy]

I wonder if the "nostrils" on the landing SD's could have some type of protective plug/cover that would pop off when they're fired for the landing maneuver?

They're abort motors too, remember. That means keeping things simple. You don't want a pop-off cover to accidentally not pop off in an abort situation.

[go4mars]

I wonder if the "nostrils" on the landing SD's could have some type of protective plug/cover that would pop off when they're fired for the landing maneuver?

They're abort motors too, remember. That means keeping things simple. You don't want a pop-off cover to accidentally not pop off in an abort situation.

Significant pressure from the expansion of hypergolics might make this idea fairly foolproof.

[Prober]

The base takes the heat. You might be thinking of the blackening of the sides of the capsule visible immediately after recovery.

This is not due to direct heating by the extremely hot plasma. It's part radiative heating of the paint, from the hot plasma passing by, and part deposition of particles from the ablating heat shield. Neither of which are going to be any problem for the superdraco pods.

Ok, but would not the deposits clog the engines if not operating?

[MP99]

Ok, but would not the deposits clog the engines if not operating?

That was my thought, too.

cheers, Martin

[starsilk]

Ok, but would not the deposits clog the engines if not operating?

That was my thought, too.

cheers, Martin

perhaps they have to be running at very low throttle during reentry?

[ArbitraryConstant]

You don't want a pop-off cover to accidentally not pop off in an abort situation.

It's difficult to imagine a way a cover wouldn't pop off with the thrust of SD behind it.

[tnphysics]

Yeah...they could be thin plastic or metal covers that would burst and be blown clear

[JBF]

Yeah...they could be thin plastic or metal covers that would burst and be blown clear

Don't they do that already for the thrusters?

[Alexsander]

Perhaps this is a better thread for it - A new tweet from Elon Musk that just went out: https://twitter.com/elonmusk/status/214831794103664640

Elon Musk ‏@elonmusk
Just fired our Superdraco escape rocket engine at full thrust! Needed to carry astronauts on Dragon pic.twitter.com/ef86qbWF

Can't wait to see the first operational test, with a unmanned Dragon hovering on air with the SuperDracos. Maybe next year?

[MP99]

Yeah...they could be thin plastic or metal covers that would burst and be blown clear

Don't they do that already for the thrusters?

I don't think those could remain on through re-entry, which was the question.

cheers, Martin

[AnalogMan]

Perhaps this is a better thread for it - A new tweet from Elon Musk that just went out: https://twitter.com/elonmusk/status/214831794103664640

Elon Musk ‏@elonmusk
Just fired our Superdraco escape rocket engine at full thrust! Needed to carry astronauts on Dragon pic.twitter.com/ef86qbWF

Can't wait to see the first operational test, with a unmanned Dragon hovering on air with the SuperDracos. Maybe next year?

Flight tests of the Dragon launch abort systems for Pad Abort and In-Flight Abort are currently estimated to be in 4Q13 and 2Q14 respectively (from September 18, 2012 presentation).

http://www.nasa.gov/pdf/698590main_NAC%20Presentation%209-18_508.pdf

[guckyfan]

Can't wait to see the first operational test, with a unmanned Dragon hovering on air with the SuperDracos. Maybe next year?

That would be cool. But I don't expect it so soon. It is not required for launch abort and that is what they need to achieve. After launch abort the landing will be in water using parachutes.

[meekGee]

Can't wait to see the first operational test, with a unmanned Dragon hovering on air with the SuperDracos. Maybe next year?

That would be cool. But I don't expect it so soon. It is not required for launch abort and that is what they need to achieve. After launch abort the landing will be in water using parachutes.

I think we'll see hover before the abort test.  It's easier to start slow and increase the testing envelope, so by the time it's an all-or-nothing test, there's more confidence in the vehicle's flight performance.

Also, it's not established that every abort scenario depletes the propellant tanks, and even when coming down with parachute, even a small amount of active control can make the difference between a safe landing and injury or loss of life.

[spectre9]

Abort tests are always high gee.

Ripping the crew capsule away from any possible explosion.

[Comga]

This is from an article in Discovery News:

"The key part of the (Dragon) upgrade (to crew carrier) is an emergency escape system so astronauts can be sprinted away from the rocket in case of an accident during launch.

SpaceX plans a launch pad abort test next year and an inflight abort test in 2014.

"We're going to launch a Falcon 9 with a Dragon on top and go up to around max Q (the point of maximum aerodynamic pressure on a vehicle) and show that we can punch it off the top and safely bring the crew away even in that critical flight regime," Reisman said last week at the International Symposium of Personal and Commercial Spaceflight in New Mexico.

If all goes as planned, SpaceX plans to test fly a Dragon capsule with its own astronauts aboard in May 2015"

Have we heard all this explicitly stated before?

[CuddlyRocket]

A question from a layman.

As max Q occurs pretty early on flight, does SpaceX need a Falcon 9 with the full set of nine engines for this test flight? They presumably need much less fuel as they have no need to get into orbit and therefore need much less thrust for both takeoff and achieving max g as well as max Q (could they get these to coincide?).

Presumably they also don't need the second stage engine (and avionics etc). Would it be wise to replace the engines with ballast of equivalent size and weight? Do they need a second stage at all and instead just mate the Dragon directly onto the first stage?

All in all, such a test flight might not cost as much as first appears?

[guckyfan]

A question from a layman.

As max Q occurs pretty early on flight, does SpaceX need a Falcon 9 with the full set of nine engines for this test flight? They presumably need much less fuel as they have no need to get into orbit and therefore need much less thrust for both takeoff and achieving max g as well as max Q (could they get these to coincide?).

Presumably they also don't need the second stage engine (and avionics etc). Would it be wise to replace the engines with ballast of equivalent size and weight? Do they need a second stage at all and instead just mate the Dragon directly onto the first stage?

All in all, such a test flight might not cost as much as first appears?

I am also a layman. But it seems to me a second stage all by itself would be enough, with the Merlin vac replaced by a first stage Merlin. Probably not fully fuelled to ensure sufficient thrust for takeoff.

Some had speculated that it could be done with the Grashopper but that is probably too heavy with its landing gear.

[Nomadd]

 No reason for a second stage, but the cost of a few engines and some fuel is insignificant compared to the rest of the test. There would be little reason to fly a unique 1st stage configuration that wouldn't be as valid for testing because of the different nature of thrust, acceleration, engine shutdown and behavior of the launcher during separation.