Updates SpaceX Falcon 9 F2 updates

Hmm...that means the escape/landing rockets and their fuel have to be protected during re-entry. Should be interesting to see how they do that.
 
Doesn't the shuttle also have some fuel left over during reentry? Then again, how much fuel are we talking about?
 
Yes, the shuttle has liquid fuel aboard during re-entry, but that is inside tanks deep inside the ship and far from the heat shield. Presumably Dragon's landing rockets will be solid-fueled and since there is no "deep inside" the small capsule they will have to be near the outer mold line, but still protected from heat.

Unless I am wrong about the fuel...
 
clickypens said:
Doesn't the shuttle also have some fuel left over during reentry?
Click to expand...
Yes, a couple of thousand of pounds of MMH/N2O4 along with pure NH3, Freon-21, raw N2H4 and active pyrotechnics.

The first ones allowed any where near the orbiter post-landing is SCAPE techs with "sniffers" that measure the toxic vapor concentration around the orbiter. Only when they have given the "all clear" is the rest of the convoy allowed inside 500 ft of the orbiter and the flight crew given the GO to doff the ACES.
 
When you need a strong burst of power in a very short amount of time, like it's typically the case in abort scenarios or for retrorocket landing (like the Soyuz), SRMs are second to none.

I really don't see how a liquid mono or bi-propellant could be used in these situations, usually it requires a lot of plumbing and a big engine to get the same power than an SRM, and I don't see where it would fit in a capsule...

Edit : I've always been curious, can the Shuttle OMS be used in atmosphere ? If yes I guess that the ISP is awful and the thrust negligible in comparison of the orbiter's mass.
 
Last edited:
So then it's probably going to be solid propellant, right? They could probably do it like in the Soyuz, right? Just a little bit bigger because of also being the LES.

I always liked the idea of a pusher LES anyway, seems easier to me.
 
N_Molson said:
Edit : I've always been curious, can the Shuttle OMS be used in atmosphere ? If yes I guess that the ISP is awful and the thrust negligible in comparison of the orbiter's mass.
Click to expand...
Minimum altitude for firing the OMS engines are 70k ft for various reasons(structural and thermal)
 
I did some number crunching on a possible pusher-LAS for the Dragon capsule. Would this be suitable to be used as a landing system? The calculations involve a lot of guessing on the initial acceleration and burn time.

For comparision:
The Apollo LES provided a push of 8 g for 3 s.
The Orion LAS would provide 14 (?) g for 2 s.

For the Dragon capsule I settled for 8 g for 2 s, which is pretty low.
Based on an up-mass of 7500 kg for a fully fueld and crewed Dragon capsule this results in:
600 kn thrust
500 kg LAS propellant (assuming an ISP of 2450 m/s)
160 m/s dV (which is lower then the 250 - 280 dV of the Apollo / Orion systems)

Distributed on - for example - 8 engines, their solid fuel blocks (without the nozzles) have a diameter and a length of 0,4 m each. Pretty much for the already cramped Dragon capsule.

If one pair is fired as landing engines this would provide 37 m/s of upward dV, which is considerably higher than the sink speed on the chute (6-8 m/s).
____

Conclusions:
1. Even for a modest pusher-type LAS the space requirements of the engines are considerable and may require redesigning the lower part of the Dragon capsule.

2. The LAS engines have to be quite powerfull. To double-use them as landing engines will require special designs. For example the LAS could consist of 6 strong and 2-4 weak thrusters. All of them would fire in case of an abort. At the landing only the weak thrusters would fire, braking the capsule from chute sink speed to zero.
 
francisdrake said:
Conclusions:
1. Even for a modest pusher-type LAS the space requirements of the engines are considerable and may require redesigning the lower part of the Dragon capsule.

2. The LAS engines have to be quite powerfull. To double-use them as landing engines will require special designs. For example the LAS could consist of 6 strong and 2-4 weak thrusters. All of them would fire in case of an abort. At the landing only the weak thrusters would fire, braking the capsule from chute sink speed to zero.
Click to expand...
How about putting the larger thrusters in a detachable shroud, [ame="http://en.wikipedia.org/wiki/Max_Launch_Abort_System"]MLAS[/ame]-style? That way, only the smaller landing rockets would need to be integrated into the capsule :shrug:
 
francisdrake said:
Conclusions:
1. Even for a modest pusher-type LAS the space requirements of the engines are considerable and may require redesigning the lower part of the Dragon capsule.

2. The LAS engines have to be quite powerfull. To double-use them as landing engines will require special designs. For example the LAS could consist of 6 strong and 2-4 weak thrusters. All of them would fire in case of an abort. At the landing only the weak thrusters would fire, braking the capsule from chute sink speed to zero.
Click to expand...

Another conclusion is that such a double use shrinks payload capability of the Dragon capsule considerably. Usually launch abort systems aren't carried all the way into orbit and back to ground.

And one more consideration, specific for a manned vehicle - I'd not feel safe knowing I'm going to splash down with some BIG solid rocket charges under my back (even safeguarded).

---------- Post added at 20:40 ---------- Previous post was at 20:16 ----------
tblaxland said:
Thanks for the video. How do they design the parachutes so that they stay separated from one another? I'm guessing that they have some strategically placed vents but how does one ensure that they are in the correct relative orientation when the chutes open?
Click to expand...

Just the right attachment, I believe.

26.jpg
 
Maybe that escape SRM pack could be jettisoned before re-entry just like the Mercury capsule retro-pack did ?
 
Spaceflight Now: Second Falcon 9 rocket passes fueling test:
SpaceX rolled the second Falcon 9 rocket to its seaside Florida launch pad and pumped propellant into the booster's fuel tanks Wednesday in a preflight countdown rehearsal.

A team of launch controllers powered up the two-stage rocket and filled it with kerosene and liquid oxygen propellants Wednesday afternoon, accomplishing a key exercise of the rocket and SpaceX engineers.

The test occurred on pad 40 at Cape Canaveral.
...
Click to expand...
 
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