The Space X Grasshopper

louis · 2013-01-13 12:16:27

http://www.spacex.com/updates.php

Does anyone know what the purpose of the Space X Grasshopper development is?

Could this be used to land and take off from Mars?

Or is it meant as a reusable craft for ferrying people from Earth to LEO?

I am intrigued by this one...need to do some more research but if anyone has any good links I will be interested to see what they have.

GW Johnson · 2013-01-13 15:57:54

Hi Louis:

Their stated purpose is an experiment vehicle that could lead to a reusable first stage for Falcon-9 (and by extension falcon-Heavy). Whether that would lead to any other applications, who knows?

For one-way Mars landings, they are looking at a version of Dragon with landing legs, that has the big Super Draco thrusters installed. These are the thrusters powerful enough to serve as the escape rocket for manned versions of Dragon. I've never worked out if the stock propellant tank size in dragon is enough for a powered landing on Mars with these Super Dracos, but the thrust levels are certainly there. I'd guess that the propellant tank size problem is solvable in some way. In some circles, this design concept has been referred to as Red Dragon. It is not intended to carry men one-way onto Mars. It might be used for a rover or sample-return mission. Or maybe one-way cargo delivery.

GW

louis · 2013-01-13 16:16:06

GW Johnson wrote:

Hi Louis:
Their stated purpose is an experiment vehicle that could lead to a reusable first stage for Falcon-9 (and by extension falcon-Heavy). Whether that would lead to any other applications, who knows?
For one-way Mars landings, they are looking at a version of Dragon with landing legs, that has the big Super Draco thrusters installed. These are the thrusters powerful enough to serve as the escape rocket for manned versions of Dragon. I've never worked out if the stock propellant tank size in dragon is enough for a powered landing on Mars with these Super Dracos, but the thrust levels are certainly there. I'd guess that the propellant tank size problem is solvable in some way. In some circles, this design concept has been referred to as Red Dragon. It is not intended to carry men one-way onto Mars. It might be used for a rover or sample-return mission. Or maybe one-way cargo delivery.
GW

Maybe they could pre-land a tank on Mars to replace the one they descend with?

Russel · 2013-01-14 08:39:22

I think the biggest influence the grasshopper will have on Mars is its effect on launch costs to LEO. If spacex achieve what they claim they'll have fuel in LEO at $1000 a Kg. At that price a lot of people will stop worrying about fuel for Mars missions and start planning missions with more margins, more contingencies, more comfort... etc. That's my take.

louis · 2013-01-14 15:10:04

Russel wrote:

I think the biggest influence the grasshopper will have on Mars is its effect on launch costs to LEO. If spacex achieve what they claim they'll have fuel in LEO at $1000 a Kg. At that price a lot of people will stop worrying about fuel for Mars missions and start planning missions with more margins, more contingencies, more comfort... etc. That's my take.

Well that will certainly be a by product of a $1000 per kg. You could probably do a Mars Mission for less than $1billion. You could probably get close to that in sponsorship alone.

Void · 2013-03-16 09:42:53

I wonder about creating a receiving robot to help in the landing.

http://www.space.com/20254-spacex-reusa … -test.html

http://en.wikipedia.org/wiki/Grasshopper_(rocket)

I hope that they will fully develop the version that they are planning with the collapsible landing gear. I want to see it work and how it works.

However I speculate on a crane machine on four or more wheels as a robot with grasping hands having air cushioned bag grips, and for that matter even during the grasp, squirting an air cushion from the fingers to help create a non damaging catch.

Then dispensing with collapsable legs on the rocket, and instead the crane robot also putting a shock absorbing cushioning device benieth the descending rocket prior to contact. There would need to be legs or leg, but that could be less complex perhaps. Another option is that the rocket would not have legs, but that pins with pads would push up from the receiving pad, as part of the robots receiving process. Maybe a padded ring pushing upward on pneumatic or hydraulic legs as the hands grasp the upper rocket body. Or maybe the "Pad" would be a partial ring, a "U" shaped pad to land on that would escape much of the rocket exhaust by being deployed sideways below the rocket body but above the rocket nozzle.

The rocket able to hover like a helicoptor according to the information given, but also the crane being able to move at significant speed laterally on the pad surface, and yet if a well made robot, being able to approach and co-operate with the rocket to secure it. This would also be useful to compensate for some degree of unexpected wind conditions. Further having the rocket secured to a wheeled vehicle, if it is desired to roll it into a shelter for inspection and service, or to protect it from comming weather conditions that also would be an option.

Having collapsable landing gear is cool, but also complicated, and I susspect a burden of complexity to add to the rocket. The objective being to recover a re-usable rocket, I think a receiving robot is worth consideration. I note that even the tires of such a device would help to serve as part of the verticle shock absorbing process. (Even though during the rocket hover it should be at almost zero verticle speed.

Granted that the robot will also cost money, but anthing to reduce the complexity of the actual air borne device may be worth it.

I guess there could be a double cost if a accedent damaged or destroyed both the rocket and the robot, but I believe that the descending rocket is very low on fuel at that point. Perhaps an explosion could be survived by the robot without total damage to it.

Think Eagle snatching a fish from a lake. It should be easier than that.

I wonder also if it was necessary to have alternate emergency landing sites if a stationary rack could be tried where the booster would dock itself, (Or try to). Say a rack with a gutter slightly tilted, (Well padded) with some kind of catch at the bottom that it would try to latch itself onto. In that case then it would have to be later retrieved by heavy equipment.

Last edited by Void (2013-03-17 22:07:31)

Impaler · 2013-03-29 03:36:39

Sounds like your describing a bit of a reverse-Soyuz pad, when the Soyuz launches its own reduced weight on the support structures cause them to open up (they have counter-weights) and release the rocket, very elegant and fool-proof system, very Russian and very Space-X.

Void · 2013-03-29 23:42:21

That would be one success story.

If i understand correctly SpaceX is creating propulsion 60-70% better than previous. (Words )

I am sure that Musk is not yet interested in a Jet assisted Grasshopper. If it is that much better, then he will luxuriate in it's winnings. However todays glory, becomes an old story. At some time, efficiency for combustion rockets must max out. From there, I would in my own mind think that a air breathing 1st stage could be added to lower costs. A Jet Pack surround of a Grasshopper type vehicle. I would expect that after it did it's work and detached, it would then land vertical on a pad.

So, at that stage in history at least the launch pad and the reception machine that catches the Grasshopper portion as it hovers, must be of a different structural configuration.

I agree that the ideal is like the Russian. I am even tempted to think as I susspect their early thinkers did that it could be used as a catapult for launch where the early arms would push up a central platform, pushing the rocket up, and to the reverse, on landing the central pad would be a shock absorber, the rocket landing/impacting, and quick clever mechanisms locking on to it to prevent damage, and the force of impact being disipated by the pushing up of the arms to surround it. However, I might prefer a wheeled grabber, an Eagle concept catching a fish, a hovering booster, hovering just above the launch pad, just above disastor. The vehicle rolling forward, a tallon (Well padded) grasping around the circumferance of the booster at a high enough position, and then a "Two tined fork" pushing in between the engine portion and the base of the booster cylinder, that fork intended to arrest vertical fall.

The Russian nest or the mobile receiver. It is a new art, hardly started. Any win is a win.

GW Johnson · 2013-03-30 18:01:35

From the site videos I have seen, the Spacex grasshopper is simply a rocket stage with a sophisticated flight control and some landing legs. It appears to set down upon nothing but a concrete apron. The thing is a dual-purpose test bed; (1) lots of throttling-burn experience with the new Merlin 1-D, and (2) experience with vertically landing a rocket stage under its own power.

Their idea with purpose (2) is to sacrifice some (perhaps a lot) of payload capability in order to not crash spent stages. I suspect the operational concept uses both chutes and a rocket-braked landing. They'll have to cut the chute to land on thrust, otherwise the straggling chute will topple the stage off its thrust vector.

As near as I can tell from the videos and their website, this is for future versions of Falcon-9 and Falcon-Heavy. They hope that reusable stages may lower total launch prices. No one is sure of that outcome, though. If it works here, then maybe later, they might consider versions of it for Mars. But not yet, not now.

The one very serious problem they will face is aero-load-induced damage and breakup of the tankage of the stage they are trying to recover. These things are tumbling at hypersonic speed when they they hit the air coming back, even just first stages. It tends to break the stages up and crush the tankage, long before it ever gets anywhere near the sea.

Those items that do survive the aero loads, tend to break up upon impact with the water, which is only a tad less abrupt than hitting concrete, at anything over about 20 mph (ask any water skier). Even the Shuttle SRB's did that all too often, and they were built to be 900 psi pressure vessels; these ordinary liquid rocket tanks are far more fragile.

GW

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#1 2013-01-13 12:16:27

The Space X Grasshopper

#2 2013-01-13 15:57:54

Re: The Space X Grasshopper

#3 2013-01-13 16:16:06

Re: The Space X Grasshopper

#4 2013-01-14 08:39:22

Re: The Space X Grasshopper

#5 2013-01-14 15:10:04

Re: The Space X Grasshopper

#6 2013-03-16 09:42:53

Re: The Space X Grasshopper

#7 2013-03-29 03:36:39

Re: The Space X Grasshopper

#8 2013-03-29 23:42:21

Re: The Space X Grasshopper

#9 2013-03-30 18:01:35

Re: The Space X Grasshopper

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