Comparison of landing methods for capsules, boosters or probes

[Slam_Jones]

Random idea here (prolly wouldn't work, but heck, might as well put it out there)

Have a vessel that utilizes a lifting body on the way up, which re-arranges itself (automatically or manually) to use the "helicopter" style blades on descent. You could potentially use the same pieces for either function, with just some minor re-assembly needed.

Prolly more science-fiction than reality, but it would be an interesting concept.

[FishInferno]

can't abort to orbit.

Not from the ground, but consider this scenario:

-Dragon V2 is flying to orbit

-Second stage engine fails midway through the burn.

-Dragon uses SuperDracos to finish the burn and achieve orbit.

-Land on Earth with the backup parachutes.

[Bill Phil]

Not from the ground, but consider this scenario:

-Dragon V2 is flying to orbit

-Second stage engine fails midway through the burn.

-Dragon uses SuperDracos to finish the burn and achieve orbit.

-Land on Earth with the backup parachutes.

That's assuming the second stage is long enough through its own burn.

And most launch abort systems are jettisoned a little after second stage firing.

[FishInferno]

That's assuming the second stage is long enough through its own burn.

And most launch abort systems are jettisoned a little after second stage firing.

But Dragon's abort system doesn't jettison.

And yes, id does depend on the progress of the second stage burn. But then you could just do a normal abort and splash in the water.

[Bill Phil]

But Dragon's abort system doesn't jettison.

And yes, id does depend on the progress of the second stage burn. But then you could just do a normal abort and splash in the water.

Launch abort systems. Not landing systems.

So why risk the possibility of making it worse? Just abort the mission.

[FishInferno]

Launch abort systems. Not landing systems.

So why risk the possibility of making it worse? Just abort the mission.

The Dragon's landing system is the abort system.

The point is that under the right circumstances you could abort to orbit if you wanted to. Ho would that make it worse?

[Bill Phil]

The Dragon's landing system is the abort system.

The point is that under the right circumstances you could abort to orbit if you wanted to. Ho would that make it worse?

If one thing goes wrong, the likelihood of other things going wrong increases, assuming those other things are dependent on the first thing. Dragon is dependent on Falcon 9. If F9 screws up, Dragon could end up in a bad orbit. It doesn't make it worse to go on, but the probability is there.

[Technical Ben]

Rockets first. Heliblades second. Parachutes third and for all/most emergencies (though not needed for unmanned, as costs are usually better in just rockets alone, and losses too low to worry about, but manned we want as near as zero losses as possible).

[Superluminaut]

Iskierka, Robotengineer, Superluminaut:

Capsule reentry does not need to be so accurate if you use the heli-blade method, it can fall at 15km/h vertital speed but with an horizontal speed of 100km/h "not sure about the real number", that's enough to correct any deviation in the reentry.

Many things was already explained in the topic, here is a recap:

helicopters landing without power:

https://youtu.be/2voCedPQMUo?t=3m

https://youtu.be/E2a9H8Xw8Mo?t=1m47s

Interesting, let me know if I'm understanding this correctly. It's similar to landing a lifting body, in that you dive down to generate enough speed for your rotors to get spun up, subsequently generating lift.

Ok so I'm convinced about it being a mass saving method, however how useful is it really? Whats the relationship between vehicle mass and the size of blades required? What kind of payloads can such a system actually land.

[magnemoe]

But Dragon's abort system doesn't jettison.

And yes, id does depend on the progress of the second stage burn. But then you could just do a normal abort and splash in the water.

An more realistic setting is if you loose an first stage engine this reduces TWR and you are not able to reach required orbit, you then use the dracos for it but has to use parachutes then landing, you are likely to have enogh fuel left to land on ground and use the engines to do an soft landing.

[sgt_flyer]

An more realistic setting is if you loose an first stage engine this reduces TWR and you are not able to reach required orbit, you then use the dracos for it but has to use parachutes then landing, you are likely to have enogh fuel left to land on ground and use the engines to do an soft landing.

If one engine only stops maybe they can simply continue the mission (like they did on apollo 13 when the S-II center engine shut down early - they simply made the others burn longer)

If one of the engine explodes, they will abort regardless of how the other engines currently works - it would be taking too much risks with lives to 'guess' if the engine explosion did damage something else or not.

[AngelLestat]

Interesting, let me know if I'm understanding this correctly. It's similar to landing a lifting body, in that you dive down to generate enough speed for your rotors to get spun up, subsequently generating lift.

Ok so I'm convinced about it being a mass saving method, however how useful is it really? Whats the relationship between vehicle mass and the size of blades required? What kind of payloads can such a system actually land.

Yeah, is a similar concept from the energy point of view than a lifting body or airplane without engine, in fact. Is easier and safe land an helicopter without engines than any airplane, plus you can land in any place (even the top of a building), not need for a runway.

About specific technical aspects, not sure yet. Is in development.

But this does not mean that we dont know if it works or not.. We know that it works.

In the 60th for the apollo program, they reach to the conclusion that it was a reliable method but they dint have time to the development.

Space industry is allergic to changes, if something "works" they keep using it without analyze if there are better ways to do it.

But well, now in the 2013 they took this concept again to finish the developing process.

You can find many ways to do it (some using existing technology) and it would work just fine.. But if you will develope something, better find the best way to do it from the begining.

This takes time.

Right now they are focus in the best way to deploy and start rotation for its own. Faster the rotation starts, faster you will have control over the capsule which translate is safety.

They are testing with passive ways of starting rotation or using alternative methods as air pressure as initial blade propulsion or small solid charges in the tip of the blades, etc.

About how much it can glide, what is the max angle.. not sure.

It will depend on how much speed can achieve horizontal.

In helicopters using autorotation is 30 degress as we can see in this picture.

I guess higher angles can be achieve it for capsules, it will depend on the drag of the capsule, weight distribution, etc.

Something like this:

More horizontal speed it means extra lift, maybe they can find a way to use the rotation energy plus the extra wind speed (apparent wind generated by your same speed as sailboats do to travel up to 8 times faster than wind) to generate more lift an forward propulsion.

Something good about rotors, is that you can open them at much higher altitude than parachutes, faster rpm is not a problem for a short blade.

Edited March 19, 2015 by AngelLestat