JP Aerospace Airship to Orbit project

[ANarwhal]

I was looking at JP Aerospace's Airship to Orbit project: http://www.jpaerospace.com/atohandout.pdf

I was with it until the third phase:

The third part of the architecture is an airship/dynamic vehicle that flies directly to orbit. In order to utilize the few molecules of gas at extreme altitudes, this craft is big. The initial test vehicle is 6,000 feet (over a mile) long. The airship uses buoyancy to climb to 200,000 feet. From there it uses electric propulsion to slowly accelerate. As it accelerate it dynamically climbs. Over several days it reaches orbital velocity.

What is the mechanism of electric propulsion? Is it simply a propeller? (I was under the assumption that a propeller would be fairly useless at that altitude due to the low air density)

For a big airship to perform this feat, I would assume that drag is minimal at this high an altitude, but will accelerating to escape velocity at this altitude still cause massive amounts of heat on the surface on the airship? Will a heat shield be necessary?

Does anyone think this is feasible?

 

[HengHY]

Not sure. Maybe they are using ion propulsion. Propeller will be quite useless in empty space.
They want to use buoyancy to climb up to 200,000 feet which is very high, which may require a very big air balloon! The airship floats high enough to escape Earth (very slowly), so i think the heat generated by drag will be insignificant compared to the direct heating from the sun radiation.

 

[Mech_Engineer]

Honestly I don't think the technical description give me warm fuzzies. It's all very hand-wavy, and provides very crude pictures of their design concepts. I have a hard time believing they will be able to lift and accelerate large payloads into orbit, but I'm not 100% clear on their entire proposed concept.

One problem I saw:

Both the climb to orbit and reentry are slow controlled processes. No high reentry heating, no big fuel tanks to explode. [emphasis added]

The energy required to reach orbit is mainly kinetic and so if they're utilizing just solar power, it will take quote a bit of solar panels to achieve suffieicnt power for large payloads. They don't really say what their paylod capacity will be, but I suspect it won't be much.

Also, how will they address the constant leaking of helium from the ship? I suspect it will be pretty bad especially in the vacuum with just a thin skin holding it in.

 

[Dotini]

Also, how will they address the constant leaking of helium from the ship? I suspect it will be pretty bad especially in the vacuum with just a thin skin holding it in.

I have to question the ability of industry to source the required volume of helium to fill a mile long airship. I do not think the US has wisely husbanded its reserves of this strategic element. I hope to be pleasantly informed I'm wrong.

Respectfully submitted,
Steve

 

[Travis_King]

I think they may mean this byelectric propulsion

I'm thinking heat will be an issue here. They say they'll spend several days reaching orbital velocity...well, heating may not be an issue in the upper levels of the atmosphere for something like the shuttle, but spending near a day at nigh-orbital velocity will not bode well for a large, blunt, thin-surfaced craft...

 

[Mech_Engineer]

I have to question the ability of industry to source the required volume of helium to fill a mile long airship.

I agree, Helium supply is something I've brought up as a concern with previous massive airship threads as well. Of course they could easily enough replace it with Hydrogen, but we all know what the hazards are with that precious little molecule...

 

[ANarwhal]

Well even though they test in Helium I never imagined they would use it. If it were up to me I would use Hydrogen and make the whole process unmanned (to prevent loss of life if the worst happened), new work in Graphene Oxides provide a reasonably effective film against the loss of light gasses.

What I am more concerned with is the drag that a non-rigid airship would go through at escape velocity, but is it actually that big of a concern at such a high altitude?

 

[willem2]

Well even though they test in Helium I never imagined they would use it. If it were up to me I would use Hydrogen and make the whole process unmanned (to prevent loss of life if the worst happened), new work in Graphene Oxides provide a reasonably effective film against the loss of light gasses.

What I am more concerned with is the drag that a non-rigid airship would go through at escape velocity, but is it actually that big of a concern at such a high altitude?

Yes. If the spaceship goes 10 km higher than the maximum altiture where it is buoyant, most of the force from buoyance is gone, so the spaceship has to move near orbital speed already, and will get an enormous drag, becuase the drag force goes up as the square of the speed.
The spaceship, which must be made of very flimsy materials, won't be able to stand the high temperatures and high dynamic pressure. You also need a saturn -V engine, to drive such a thing, not an ion engine.