[yt="New Johnny Cash hoverslam test"]NoxiK7K28PU[/yt] It's going to be amazing if they can succeed in the plan to make the falcon 9 entirely reusable.
It'll be interesting to see how they manage to pull it off. The first and second stages aren't terribly difficult, aside from the issue of weight. The parachutes and floats will add parasitic weight, but the third stage (which kicks the capsule/satellite into final orbit) is another kettle of fish entirely. Of course, its possible that they'll do something similar to what was proposed doing with the shuttle's tank, that was never done: park it in orbit for use there as a basis for building a space station.
No parachutes, no floats. They're aiming to do powered landings. [yt="madness"]0H_cjfk5v1k[/yt] Obviously payload will be reduced, but they're hoping the reduced costs will make up for it.
I wonder if the descent stages need their own oxidizer supply or whether they can pull atmospheric oxygen, something the lunar and Mars landers could never do.
That's an interesting idea, I wonder if the extra weight and engineering needed to switch between tank oxidiser and atmospheric oxygen would exceed the weight savings of just carrying it.
My bad for not watching the video, though they're doing the 'chutes and floats on the first stage currently and talking about doing the same on the second stage. AIUI, at high altitudes, you either have to go really fucking fast, or go with an onboard oxidizer. Modern software can handle the issues that plagued the Pogo, but without significant advances in lightweight materials, I can't see this being practical for heavy lift launchers.
I wonder what's keeping a company from using some kind of magnetic track launch system. If you go to an area like the salt flats where there is plenty of long flat space to build up speed you could potentially get enough speed built up to literally be thrown into orbit. The video above is really amazing technology but it must be very expensive. If you could launch something that had fueled engines without the need to use the fuel to get to space then it could be used to control your journey once you're there and to help control your landing, whether it be on the Moon or Mars, or back here on Earth. The other option would be the use of a rocket based launch system to carry heavy loads of fuel to space and leave them at a refueling space station so that mag-launched light crafts could be as light as possible (no fuel) to launch into space and then dock at the space station, fuel up, gather supplies and continue their mission from there. It really does make the most sense to launch long distance missions, such as Mars, from orbit. But that does require putting the refueling station in orbit and getting that whole system in place to begin using. While it would save money in the long run the initial cost is probably quite prohibitive because I doubt the existing space station could be retrofitted to serve this purpose, even if NASA and Russia were willing to help out.
Pretty neat but we see the rocket uses it's engine all the way back to Earth. That's a lot of fuel. Why not parachute down and then in the last thousand feet fire up the rocket?
I'm curious about this, and also wonder why it makes the booster more ready for reuse than a parachute based recovery.
Deadfall parachute landings ARE NOT SOFT. People break bones with that shit pretty regularly (why we get paid an extra $125 a month) and more rarely some die. I imagine sensitive hardware that doesn't have the ability to bend joints and flop (PLF) hits even harder.
A linear accelerator requires a big power source if you're not going to be using superconducting magnets. If you plan on using it to send up humans or have electronics functioning during launch, then you've got to protect them from the magnetic fields. This means putting everything in a Faraday cage on the inside of the vehicle, which adds weight. You've also got to have some kind of abort system, so if your vehicle gets shot out with less than ideal velocity, it doesn't splatter in a populated area. Parachutes are a bitch to deal with, and you're essentially going to be dealing with virgin hardware each time, because you'll need things like new explosive bolts and the like for each launch.
I'm curious about this, and also wonder why it makes the booster more ready for reuse than a parachute based recovery.[/QUOTE] Parachutes are a bitch to deal with, and you're essentially going to be dealing with virgin hardware each time, because you'll need things like new explosive bolts and the like for each launch.[/QUOTE] In refurbishing the rocket for reuse are they not going to need new parts on a regular basis anyway?
You aren't going to achieve orbital velocity that way, but something like that could possibly eliminate stages, especially if it was to build up speed to start up scramjet engines without the need for a rocket booster. Then rockets would only be needed for the upper atmosphere where the air is too thin for air-breathing engines.
A parachute possibly wouldn't be worth the hassle and most of the descent rockets I would suspect to be for stabilization and not actually slowing descent until the last couple of minutes. The terminal velocity would be in the 200-300km/h range if I recall correctly.
I'm actually somewhat curious about the possibility of a booster stage that has wings, so it could return on a glide, possibly automated or remotely operated. Of course wings big enough to create enough lift for the return would probably cause a large amount of drag on the way up.
Using vacuum tubes you can theoretically achieve 4,000 mph. That is a good start. It would save on fuel.
You know, given what we're able to do with things like carbon fiber, I'd think that it'd be possible to do something like inflatable wings, which would be deflated for launch, and then inflated on the way down. This would eliminate the drag issue.
The only limitations on magnetic acceleration are the length of the accelerator and the power you feed into it. A large accelerator in space that was like 100 miles long and powered by a solar array the size of a small country could probably fire off projectiles at significantly cee-fractional velocities.
Maybe, but the cost to send up 100 miles of track would be astronomical. In space, even a short distance track should be able to generate speeds well beyond that which can be reached on Earth because there is no resistance from the atmosphere and no gravity. But that doesn't really solve any problems. We're talking about decreasing the cost to send something into orbit. Once in orbit you only need to have a burst of speed to send you on your way; after that nothing is going to slow you down until you use engines to provide push back the other direction or use a planet or moon's gravity in some way. Also, anything in orbit is already going 17,000 mph. So really all they have to do is break orbit in the direction they want to go. I can't see any reason to stop and launch off a magnetic track once you're up there.
In space, it wouldn't work at all, because the track would accelerate off in the opposite direction and never return.
It would recoil, certainly, but if the track were much more massive than the vehicle, the track's delta-v would be small. Suppose the track is 10,000 times more massive than the vehicle, and the final velocity on the vehicle were .01c, then... By conservation of momentum, momentum of track = momentum of vehicle m1v1 = m2v2 [conservation of momentum] (10000m2)v1 = m2(.01c) 10000v1 = .01c [divide through by m2] v1 = (.01/10000)c [solve for v1, track recoil speed] v1 = .000001c = .186 miles/sec = 983 feet per second You could offset the recoil by firing a dummy projectile in the opposite direction.
A better place for the track would be the moon. 4,000 mph would be more than enough to break orbit on the moon so it could be used to relaunch without the need for rocket fuel.
