Elon Musk doing Q&A on Reddit
January 5, 2015 9:16 pm Eastern | by Clark Lindsey, Managing Editor [Launch Vehicle Providers]
Elon Musk is curently (9:00 pm - 10:00 pm EST) answering questions at I am Elon Musk, CEO/CTO of a rocket company, AMA! : IAmA.
A sampling of his responses:
Elon:
Yes, the Falcon Heavy center core is seriously hauling a** at stage separation. We can bring it back to the launch site, but the boost back penalty is significant. If we also have to the plane change for geo missions from Cape inclination (28.5 deg) to equatorial, then a downrange platform landing is needed.
The Mars transport system will be a completely new architecture. Am hoping to present that towards the end of this year. Good thing we didn't do it sooner, as we have learned a huge amount from Falcon and Dragon.
Our spacesuit design is finally coming together and will also be unveiled later this year. We are putting a lot of effort into design esthetics, not just utility. It needs to both look like a 21st century spacesuit and work well. Really difficult to achieve both.
Elon -
Actually, we could make the 2nd stage of Falcon reusable and still have significant payload on Falcon Heavy, but I think our engineering resources are better spent moving on to the Mars system.
MCT will have meaningfully higher specific impulse engines: 380 vs 345 vac Isp. For those unfamiliar, in the rocket world, that is a super gigantic difference for stages of roughly equivalent mass ratio (mass full to mass empty).
...
With sub-cooled propellant, I think we can get the Falcon 9 upper stage mass ratio (excluding payload) to somewhere between 25 and 30. Another way of saying that is the upper stage would be close to 97% propellant by mass.
Elon -
The grid fins are super important for landing with precision. The aerodynamic forces are way too strong for the nitrogen thrusters. In particular, achieving pitch trim is hopeless. Our atmosphere is like molasses at Mach 4!
Elon -
Thrust to weight is optimizing for a surprisingly low thrust level, even when accounting for the added mass of plumbing and structure for many engines. Looks like a little over 230 metric tons (~500 klbf) of thrust per engine, but we will have a lot of them
Elon (Design life of the Merlin engine?) -
There is no meaningful limit. We would have to replace a few parts that experience thermal stress after 40 cycles, but the rest of the engine would be fine.
Elon -
Goal is 100 metric tons of useful payload to the surface of Mars. This obviously requires a very big spaceship and booster system.
Elon (Will the MCT use 3 cores or one?) -
At first, I was thinking we would just scale up Falcon Heavy, but it looks like it probably makes more sense just to have a single monster boost stage.
Wątek: SpaceX (Przeczytany 1376902 razy)