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

[David Doumèche]

It's a well know fact than reusable spacecrafts are more expensive than dispensable ones:

- it require a much stronger frame, heavier, then the weigth is taken from payload. Shuttle payload was reduced by 20% over requirement

- maintenance is very larbor intensive, you don't return on earth by gravity without suffering high thermal dommage.

- you get a very complex system, very expensive, with a small fleet. Over time, safety is reduced and you end up losing more astronauts than with a Soyuz.

[Clark Lindsey]

It's even better known that one cannot generalize from 1 data pt. The first tries at any technology always fall far short of what will be accomplished after variations & refinements. The DC-3 came after many tries at a practical airliner. The Shuttle had many design flaws & was refurbishable, not reusable. Fuel is 0.3% of F9 cost. Rest is in lost hardware. Saving hardware more than makes up for less payload to orbit, robust TPS,etc. A prime goal of reusable F9 is fast turnaround with small crew.

[drumchakra]

And it cannot eve carry enough fuel. That's the lie tht makes the investment a scam to those that he suckered into this fail.

[Clark Lindsey]

Please get your basic facts correct before accusing people of crimes. The reusable Falcon is totally funded by SpaceX. Not by NASA or outside investors. Elon Musk is not wasting his time and money if the calculations and simulations don't say it will work. There are plenty of real world details that could still cause it to fail but they are going to put plenty of blood, sweat, and tears into trying to make it work.

[drumchakra]

I never meant to imply a crime was committed. It's no crime to sell stock to dreamers even if the dream is impossible.

[Clark Lindsey]

They are not selling stock. They are not getting investment from outsiders for the reusable F9 project.

[Clark Lindsey]

The goal is not just to return but to return in a way that leads to rapid turnaround and re-flight. That requires coming back to a specific spot and with minimal overhaul. A booster is a thin structure that doesn't like hitting the ground even at parachute speeds. The Kistler K-1 RLV design used chutes but needed airbags to cushion its landing. That means more wt and complexity. SpaceX may end up using at least drogue chutes to reduce the speed but they won't give up powered landings easily.

[Clark Lindsey]

The fuel is standard rocket grade kerosene and the oxidizer is liquid oxygen. The keys are lowering non-fuel mass as much as possible, raising the performance of the engines, and trading off some payload mass for reusability. Reducing payload is made up with the higher launch rate provided by reusability. I can't put a URL here but if you Google on "Musk, Simberg, Popular Mechanics" you can find an interview in which Musk discusses the strategy and tradeoffs in their RLV design.

[Trent Waddington]

SpaceX is selling stock, ya know. :)

[Sarge Rho]

The first stage lands back at the pad it lifted off from. It does a backflip and turns around to do that, then lands.

[georgeman27]

true, but it still needs some fuel to slow down at touchdown. Presumably the second stage would complete 1 orbit and land at the launch pad, but I would be interested to know where does the first stage land.

Unless thy start the gravity turn after the separation of the first stage, it would have to land a few hundred km from the launchpad and than it would have to be transported back...

[Sarge Rho]

Not really. The 2nd stage just needs to slow down enough so that its trajecty takes it into the denser parts of the atmosphere. The first stage doesn't reach orbit at all.

[aptom203]

The DeltaV required to land is much, much lower than that required to get it up there in the first place, because it doesn't have to carry all that heavy fuel.

[Sarge Rho]

Do you know how many reusable spacecraft have been in active service?

NONE. The Shuttle was partially reusable - the expensive fuel tank was always lost. Other than that, there aren't any.

"and you end up losing more astronauts than with a Soyuz."

Soyuz is far safer than the Shuttle. 4 deaths on Soyuz, 14 with the Shuttle.