SpaceX's 10-story reuseable Grasshopper rocket takes a bigger hop

Nov 05, 2012 by Nancy Atkinson, Universe Today
Artist’s rendering of SpaceX Falcon 9 rocket landing itself. Credit: SpaceX

SpaceX is developing the "Grasshopper" reusable vertical takeoff, vertical landing rocket. Back in September, the 32-meter- (106-ft-) tall Grasshopper made a tiny hop – barely lifting off the pad just to test-fire its engines. But now the Grasshopper has made a second, bigger hop. Over the weekend, Elon Musk quietly tweeted a link to a video, saying, "First flight of 10 story tall Grasshopper rocket using closed loop thrust vector & throttle control."

SpaceX hasn't talked much about this , but reportedly the goal with is to eventually create a reusable first stage for its Falcon 9 rocket, which would be able to land safely instead of falling back into the ocean and not being usable again.

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Here's some info about the Grasshopper from a draft environmental impact assessment put out by the FAA in 2011:

The Grasshopper RLV consists of a Falcon 9 Stage 1 tank, a Merlin-1D engine, four steel landing legs, and a steel support structure. Carbon overwrapped pressure vessels (COPVs), which are filled with either nitrogen or helium, are attached to the support structure. The Merlin-1D engine has a maximum of 122,000 pounds. The overall height of the Grasshopper RLV is 106 feet, and the tank height is 85 feet.

The propellants used in the Grasshopper RLV include a highly refined kerosene fuel, called RP-1, and liquid oxygen (LOX) as the oxidizer.

The reports goes on to say that the Grasshopper test program is to have three phases of test launches, at SpaceX's facility in McGregor, Texas. Phases 1 and 2 would consist of very low test fires with the rocket rising to not more than 73 meters (240 feet) during Phase 1 and 204 meters (670 feet), which is below controlled-airspace. Both Phase 1 and 2 flights would last up to 45 seconds.

Phase 3 tests have the goal of increasingly higher altitudes with higher ascent speeds and descent speeds. The altitude test sequence likely would be 366 meters (1,200 feet); 762 meters (2,500 feet); 1,524 meters (5,000 feet); 2,286 meters (7,500 feet); and 3,505 meters (11,500) feet. The maximum test duration would be approximately 160 seconds. If all goes well, the Grasshopper would land back on the launch pad.

Here's Grasshopper's first little test hop in September, which SpaceX said went 2 meters (6 ):

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Look for more details on this exciting reusable rocket as SpaceX continues its tests of the Grasshopper.

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User comments : 17

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ShotmanMaslo
1.3 / 5 (3) Nov 05, 2012
Reusability is great, but I dont think it will be much cheaper until launch rate also increases considerably.
eljo
4.8 / 5 (4) Nov 05, 2012
Non-reusability is like building a house, sleeping one night in it, levelling the house and building another one.

You do the math.
hemitite
3 / 5 (2) Nov 05, 2012
The extra fuel saved for landing would have to be added to the 1st stage payload, which would mean that the "Grasshopper" would have to be larger and heaver than a non-reusable 1st stage. I wonder where the break even point is?
GSwift7
4.7 / 5 (3) Nov 05, 2012
would have to be larger and heaver than a non-reusable 1st stage. I wonder where the break even point is?


I was wondering the same thing. I guess that also depends on how many times you can really reuse it.

I also wonder how you get it to come back down at the launch pad? Rockets don't take off straight up. It would need to steer itself back to an extremely flat and level surface for a good landing. It's amazing that they can get a 100 food tall tower to land upright on such a narrow landing gear. I guess those landing gear are folded up into a faring for launch. I'll bet it's a bit sensitive to wind conditions when landing. They'll need some way to quickly sucure it once it is on the ground.

This reminds me of the old cartoons where they had rocket ships landing vertically like this.
fmfbrestel
5 / 5 (4) Nov 05, 2012
If you are interested in the details on just how Spacex intends to solve all of these problems, the nasa spaceflight forum is stuffed with superb information. Here is the link to the SpaceX section:
http://forum.nasa...ard=45.0
fmfbrestel
5 / 5 (1) Nov 05, 2012
The landing gear shown here is very obviously beta config, and WAY to big and bulky for a production rocket. Rule of thumb for weight penalties -- first stage is 10 to 1 payload loss. ten pounds of extra first stage weight subtracts 1 pound from payload to orbit. Second stage is closer to 1 to 1.
dschlink
5 / 5 (2) Nov 05, 2012
The bigger problem: finding a place down-range for the booster to land without using too much fuel. Neither Florida or California offer any good prospects. But combine soft landing with the Stratolaunch vehicle and you have a winning combination.The mother ship can take off and fly UP-range before launching.
javjav
4.8 / 5 (4) Nov 05, 2012
The extra fuel saved for landing would have to be added to the 1st stage payload, which would mean that the "Grasshopper" would have to be larger and heaver than a non-reusable 1st stage.

Not exactly. The Falcon rocket has to carry some more fuel than it is required, just in case one of the 9 engines fail and it has to flight in a less efficient mode (as it happened in last flight). A reusable rocket could use that extra fuel in the final seconds of descent (most of the descent would be parachuted), although it would be a rocket of one use in case of engine failure.
Also a reusable rocket could use more efficient engines and lighter materials (for example carbon nanotube fibers or graphene), which are already available, but SpaceX do not use them just because their cost is too expensive just for a one time usage. So a reusable rocket could be even lighter and smaller!
SarK0Y
4.3 / 5 (4) Nov 05, 2012
So a reusable rocket could be even lighter and smaller!

even if new materials shall make possible to reduce launch weight, it does no mean the overall cost will be lower than conventional way 'cause new materials can be too expensive.
RobotB9
5 / 5 (1) Nov 08, 2012
I would disagree with the "reusable is lighter" statement. Its a matter of factors of safety. A machine of almost any kind that only needs to be used once will have to deal with lower fatigue problems and can have a lower factor of safety (lower mass) then a machine that needs to be used more then once.
wiyosaya
5 / 5 (2) Nov 09, 2012
Anyone remember the TV show "Salvage-1"? Sci-fi becomes reality with this.
I would disagree with the "reusable is lighter" statement. Its a matter of factors of safety. A machine of almost any kind that only needs to be used once will have to deal with lower fatigue problems and can have a lower factor of safety (lower mass) then a machine that needs to be used more then once.

I agree with the increased fatigue issue; however, I would think that if monitored correctly, the cost of replacing components of a rocket that have gone beyond their useful life would be less than replacing the rocket itself. This may not be true, though.

In the long run, one would think that most, if not all, of the reusable rocket's components would have to be replace over time due to fatigue and/or other "wear" issues. It would seem that this is a cheaper approach than replacing the rocket every time. What plays out in practice remains to be seen.
antialias_physorg
4.3 / 5 (3) Nov 09, 2012
So a reusable rocket could be even lighter and smaller!

A reusable rocket that can land of its own is MUCH heavier than the throw-away kind because it needs to carry A LOT more fuel.

It has to handle lift off AND landing - and during lift off it has to accelerate the additional weight of the fuel carried for landing (which cuts severely into the payload).

On the up-side: If you have a stable of reusable rockets you can launch more frequently than if you have to build a new one each time. And building one is probably more expensive than having one that has less payload but where you only need to pay for (more) fuel.
ShotmanMaslo
5 / 5 (2) Nov 09, 2012
Rockets always carry more fuel than needed to complete the mission as a reserve, so the fuel increase needed for a reusable rocket is not that great.

An almost empty rocket stage is light and has great volume, an ideal combination for reentry and landing.
baudrunner
not rated yet Nov 10, 2012
This is what NASA had way back in the sixties, in preparation for the moon landing. Okay, so they weren't talking re-usable rocket, but just the same, I will not be truly impressed until SpaceX sends one into orbit and brings it back, then refuels it and does it again. That would be true proof of concept, and only then would we be ready for a Mars expedition using the system.
rjsc2000
1 / 5 (2) Nov 11, 2012
Don't forget the cost. Is it cheaper?If not, then don't do it.
Shouldn't we seek some kind of anti-gravity device instead??
lengould100
5 / 5 (1) Nov 12, 2012
Don't forget the cost. Is it cheaper?If not, then don't do it.
Shouldn't we seek some kind of anti-gravity device instead??

Yeah, I'd love to work on that project, as long as you'll handle all the funding application issues.
antialias_physorg
5 / 5 (1) Nov 12, 2012
Shouldn't we seek some kind of anti-gravity device instead??

Seeking only works if you have a idea of how to do it.
If you have: go ahead.

The only really theoretically worked out thing out there in that regard would be a stationary Alcubierre drive. And the energy requirements for that sucker are enormous (depending on what type of setup we're talking the energy equivalent of the mass of Jupiter to several solar masses. But there are guys who think that this requirement cn be brought down somewhat).
Oh...and it also needs negative energy.