SpaceX Reusable Launch System

An animation of a launch of SpaceX Falcon 9 with Dragon showing powered vertical return of both stages and the Dragon

Credits: SpaceX
www.spacex.com/assets/video/spacex-rtls-green.mp4

Category:

Science & Technology

Tags:

• spacex
• VTVL
• reusable
• rocket

[NASAvsPETE5]

@HobbySpacer "According to Musk", if this was possible they would have done this years ago, parachutes are what they use now, infuse its working out how much fuel is required to slow the vehicle down and balance it in normal gravity, simulations will always be very different to the real thing.

[HobbySpacer]

You are going to be surprised. There are lots of things not done "years ago" that are in fact quite possible. There is no all-knowing "they" who decides such things. No fundamental physics laws prevent powered return. The calcs and sims are in fact perfectly suitable for showing it will work in principle.

You are right in the sense that sims can never guarantee real world hardware will perform as in sims. That's what tests are for. Tests start this year of the reusable 1st stage prototype.

[NASAvsPETE5]

it would need enormous fuel tanks to do what is depicted, much larger & possibly external. Great imagination however.

[HobbySpacer]

SpaceX just put a Dragon capsule into orbit and on the way to the ISS. Takes a great imagination to clam they don't know how to do rudimentary rocketry calculations and simulations.

According to Musk, the payload to orbit falls by about 40% with the reusable compared to the expendable for the same sized vehicle. That loss of payload is more than made up by the big drop in costs and the big increase in flight rate.

[Elukka]

You're ignoring two factors: The atmosphere and that the vehicle will be almost empty by the time it's landing. The atmosphere will slow it down to at most a couple hundred m/s for 'free' and it won't take too much fuel to halt a very light vehicle from that meager speed.

What'll take more delta-v is returning the first stage to the launch site. I don't know how much exactly, but I suppose they've figured they can do this. It's probably part of why they're working on a stretched first stage.

[HobbySpacer]

Along with the tank extension, they are also switching to the Merlin 1D engine, which increases thrust from 616 kN to 690 kN (in Vac) and thrust/wt from 96 to 160. Those improvements probably make up for the 40% loss in payload to orbit with the reusable stages that Elon cited in his Popular Mechanics interview (ow.ly / b7bRn). The Falcon Ver.1.1 will become the standard vehicle after mission 5.

[Eagle1Division2]

But the impressive thing about SpaceX, is rather than just promises, they've already delivered. Cut launch costs down to ONE-FOURTH, with the same rocket that has safety margins far greater than the norm, developed cutting-edge PICA-X, made a capsule in less time and less than 1/10th the budget of Orion, and their Merlin engines hold the record for most efficient American hydrocarbon engine.

SpaceX has a history of delivering what they say they will.

[baillou2]

The first stage is going so fast that a gliding wing design would be ripped to shreds. As it is the stage is being heavily pummeled. As Elon says "it's belly-flopping on the atmosphere." What's needed is a means of braking before it gets into heavier air. And for that you need thrusters.

And yes, it would add WAY too much weight. Better to just used the on-board hardware that already exists.

From what I've heard the landing gear is already pushing the weight limits.

[KT315D]

hollywood does these things better! LOL

[Omnifarious0]

This is interesting. I'm surprised they don't try for a glider transform on the first stage in order to also take advantage of atmospheric braking, but also to steer it to the right location. Of course, that's pretty complicated mechanically, and the mechanics might add more weight than it's worth.

[arsalanmunir]

very futuristic. love the simulation. love to see this in reality.

[Elukka]

160... That's amazingly high, no other engine comes close. NK-33 has an exceptional t/w ratio of 137 and it's been the best in that respect for nearly four decades.

I thought the numbers didn't add up since the thrust isn't that much higher than the Merlin 1C's but I found mention that it's also significantly lighter so that's probably it.

[NASAvsPETE5]

@Elukka One more thing, the simulation doesn't take into account weather or cross winds, unless weighted these rocket landers are likely to enter into a flat spin, gyros will assist, but will also use buckets of fuel if it's windy. Good luck by the way, not here to Rain on Musks parade, hes already made history, hope he keeps going, it's all looking pretty good so far!