Elon Musk's ISDC 2008 Comments

[iamlucky13]

Hmm...more on reusability:
"Making second stage for Falcon 9 reusable is difficult. - TPS, parachutes, seawater hardening, etc"

First stage I can definitely understand, especially with 9 engines. But I really wonder how much 2nd stage recovery costs them in terms of payload.

Also:
"Manned Dragon? Schedule depends on NASA option D. If they approve that, could have crew version by 2011. Otherwise, with internal funding it will take longer (~2013). Difference between cargo Dragon and a crew version are fairly minor. Need to develop an escape rocket."
I'd be careful about calling that minor. I also wonder how much they've looked at payload effects of that. Presumably they've got the basics covered...making the capsule strong enough for it, figuring in mass allowance for carrying a protective cover and the motor most of the way to orbit, etc. Trading back and forth between 2500 kg cargo or 7 crew plus 2-3 days life support and the escape system, however, I have to wonder if they might be planning on a baseline of using the escape motor for extra delta-V...which NASA considered and has more-or-less discarded for Ares-1/Orion.

[docmordrid]

Going back a few posts re: couches and weight.

Seems to me there has been lots of work on web/cloth couches that can be stowed after launch by several groups including NASA.  I can't see those taking much out of the cargo throw.

[bad_astra]

I can no longer recall the exact figures for the swiveling chairs TSpace proposed, but they were very light.

[nacnud]

I think it was 1/10th of a shuttle chair, not sure though.

To go really minimal you could look into harnesses rather than seats, even as far as building the harness into the launch/entry suits.

[kevin-rf]

To go really minimal you could look into harnesses rather than seats, even as far as building the harness into the launch/entry suits.

I believe you would want to, just to make sure it is perfectly fitted to the suit and does not slip or shift on reentry. Nothing could be worse than having the upper torso links shift resulting in a head down astronaut during the high g's of reentry.

Nor is it uncommon to build the harnesses into protective suites, many swift water and high angle rescue crews build them into there gear. I even know a few vendors who will sew them into caver coverals.

I wonder how many links would be required, upper torso, torso, arms, legs, head, it would be an interesting spider web when all is said and done.

One down side of this is securing the victim eeer... user and providing a method to quickly unhook. Most devices do not release while loaded. With a couch you are not applying force to the belts when unhooking them, that is not the case when hanging from the supports, they are loaded.

[HMXHMX]

I can no longer recall the exact figures for the swiveling chairs TSpace proposed, but they were very light.

13 pounds mass

[Swatch]

I vote for Velcro....just slap the astronauts up against the wall like one of those Japanese tv-shows.  :-)

But seriously.... I would have to guess that fabrics and harnesses will be the future of spaceflight seating.  They offer many advantages, the least of which is weight savings.  They also allow for much more efficient use of cabin space as they are highly stowable.

[guru]

I have to wonder if they might be planning on a baseline of using the escape motor for extra delta-V...which NASA considered and has more-or-less discarded for Ares-1/Orion.

One of the early X-Prize entrants, Canadian Arrow, considered something like that as well for their suborbital vehicle.  Their projected second stage would have consisted of four motors that were integrated into a frame with the same diameter as the first stage, and it would have doubled as the escape motor.  That option probably has a larger weight penalty than a top mounted LAS though.

[kkattula]

... I have to wonder if they might be planning on a baseline of using the escape motor for extra delta-V...which NASA considered and has more-or-less discarded for Ares-1/Orion.

The problem with dual use is different thrust profiles: 

LES needs very high thrust for a very short period of time, low total impulse, and has to work at low altitude. (low ER nozzle).

OMS usually needs fairly low thrust for a much longer period, much higher total impulse, and only needs to work in space (high ER nozzle).

Trying to do both jobs will probably compromise one or both unacceptably.


Apparently Dragon's oversize RCS will also do the OMS role including orbital insertion, around 520 m/s delta v. So the two LES options are:

1)  A dedicated escpae tower with most likely solid rockets.

2)  Dedicated escape engine(s) in the service module using RCS fuel.