JP Aerospace to compete for America's Space Prize

Space Race News reports that JP Aerospace has declared their intent to
compete for the $50 million America's Space Prize:

http://www.xprizenews.org/index.php?p=731

Their plans call for a three-stage approach to get to orbit, with an
airship taking people/cargo up to an inflated station at 140,000 feet,
with a separate orbital airship leaving from the station, propelled by
ion thrusters:

http://www.jpaerospace.com/atohandout.pdf
http://www.hobbyspace.com/AAdmin/arc...alAirship.html
http://www.jpaerospace.com/

JP Aerospace led to a couple of vivid discussions last year:
http://groups-beta.google.com/group/...k+to+Search&&d
http://groups-beta.google.com/group/... f3dbca01aa46

yo, whatever.
Their graphics are really nifty. But I have a very practical question:
just how do they envision transferring cargo and fuel from the ground
airship to the orbital airship in a near zero atmosphere environment?
The Dark Sky platform they show doesn't literally have a platform on
it. Are there going to spacesuited techs performing all the labor? how
do they move around the platform?

At the most basic level, they talk about using the Dark Sky platform to
actually inflate and launch the orbital airship. How do they plan to do
all this? It's not a question of proprietry technology, either, which
leads one to suspect they don't mention it because they haven't figured
out how to do it yet.

Tom Cuddihy

ok, after reading the Space Review article on it I see that question's
been raised a lot. Just the same, the video JP puts out shows the
ground airship docking with a clearly pressurized section on one leg of
the platform. I suppose it is possible to have both the groundship and
the orbital ship dock at the same place. BUt how do you build the
orbital ship in such a small area to begin with?
I guess we'll see what we'll see.

Tom Cuddihy

"Neil Halelamien" wrote in
oups.com:

http://www.jpaerospace.com/

At first glance it sounds like a pretty cool idea. They are going to launch
a V shaped airship from a "station" that is already floating above earth at
100,000ft. Usually the stuff that holds up a balloon is its displacement
of air, but in this case, its going to be replacing that with lift as it
gets higher and higher (according to them lift is going to be possible
because the lower densities will permit a higher speed). Also, the idea of
solar-electric/ion propulsion is natural...its really the only option for
sustained thrust at that altitude.

My questions are....if you have that much lift, you're going to have some
problems with drag. How are you going to get eneough thrust to overcome it?
The ion propulsion systems are measured in grams of thrust....yet I'm sure
with a mile long airship, there will be more drag than that almost all the
way up to orbit. Let alone having eneough left over for acceleration.
Also, I'm having trouble imagining getting the lift needed when moving from
the bouyancy to the orbital microgravity realm. This is going to be
hypersonic aerodynamics....this is pretty tough stuff to model.

Anyway, I'm curious what other people think of this idea. It sounds kinda
cool, like something that should be investigated, but not something we
should go sink millions of dollars into.

Tom

In article 4,
Tom Kent wrote:

Anyway, I'm curious what other people think of this idea. It sounds kinda
cool, like something that should be investigated, but not something we
should go sink millions of dollars into.

Fortunately, we're not sinking anything into it. JP Aerospace is making
each step pay for itself. Though expecting to get to orbit in 7 years
seems a bit ambitious to me, I still dig what they're trying to do and
wish them the best of luck.

,------------------------------------------------------------------.
| Joseph J. Strout Check out the Mac Web Directory: |
| http://www.macwebdir.com |
`------------------------------------------------------------------'

Fortunately, we're not sinking anything into it. JP Aerospace is
making
each step pay for itself.

Even if they do get to orbit, they will still be bound by rules of
profitability. The question is--even if they can pay for the
development itself, will it be economincally feasible to pay for the
extremely large infrastructure (groundship, dark sky station, and
airship)--I mean upkeep, repair, etc--based on a launch method that
apparently takes weeks to get to orbit. This is not like an elevator,
that can be continuously moving payloads up and down and has very small
weight limits. In the elevator's case, its the lack of significant
weight restrictions that makes it economically feasible, just like the
intercontinental railroad beat out the pony express.
This launch method, on the other hand, will be reusable--assuming the
craft can survive more than one trip. But it will still have very
restrictive weight limits, and I'm not sure the profitability is any
better than a TSTO RLV.

In article .com,
"Tom Cuddihy" wrote:

Even if they do get to orbit, they will still be bound by rules of
profitability. The question is--even if they can pay for the
development itself, will it be economincally feasible to pay for the
extremely large infrastructure (groundship, dark sky station, and
airship)--I mean upkeep, repair, etc--based on a launch method that
apparently takes weeks to get to orbit.

It takes about five days, not "weeks."

This launch method, on the other hand, will be reusable--assuming the
craft can survive more than one trip. But it will still have very
restrictive weight limits, and I'm not sure the profitability is any
better than a TSTO RLV.

Yes, that's certainly a fair question.

,------------------------------------------------------------------.
| Joseph J. Strout Check out the Mac Web Directory: |
| http://www.macwebdir.com |
`------------------------------------------------------------------'

It takes about five days, not "weeks."

The way I read the publically available info, it takes 5 days to go
from the Dark Sky station to orbit alone. Add in the time to return
from orbit, and conduct any necessary refurbishment, etc, plus the next
transfer from ground, etc, and it sounds like you can't repeat flight
rate in other than a couple weeks.

although anything is better than the "no repeat" of standard launchers.
I just don't see an easier path to orbit by this method: SpaceX's
apparent slow transition from affordable semi-reusables TSTOs to fully
reusable TSTOs seems much more applicable to the market, since the
precursors (non reusable and semi-reusable TSTOs) serve the same market
as the eventual destination, whereas the precursors from this
perspective (military reconnaissance UAVs, communications platforms,
etc) do not serve the same market. So the inevitable big differences in
product development may make even the profitable elements (like a
military recon system) not actually help in paying for the orbital
system.

Joe Strout wrote:

In article
.com,
"Tom Cuddihy" wrote:

Even if they do get to orbit, they will still be bound by rules
of profitability. The question is--even if they can pay for the
development itself, will it be economincally feasible to pay
for the extremely large infrastructure (groundship, dark sky
station, and airship)--I mean upkeep, repair, etc--based on a
launch method that apparently takes weeks to get to orbit.

It takes about five days, not "weeks."

I tried this in sci.space.tech last year with little response so
I'll give it another try here since you raised the subject.

Even if one ignores aerodynamics (ie, assume infinite L/*D) the
scheme doesn't seem to add up. Take the following statements from
th*eir handout:

"The third part of the architecture is an airship/dynamic ve*hicle
that flies directly to orbit. In order to utilize the few mo*lecules
of gas at extreme altitudes, this craft is big. The initial *test
vehicle is 6,000 feet (over a mile) long. The airship uses b*uoyancy
to climb to 200,000 feet. From there it uses electric propul*sion to
slowly accelerate. As it accelerate it dynamically climbs. O*ver
several days it reaches orbital velocity."


"Once in orbit, the airship is a spacecraft. With its
solar/electric propulsion, it can now proceed to any destina*tion in
the solar system."


"The ion engine 120,000 foot flight test for the orbital air*ship
will be flown in the next five months."


The airship in orbit has a specific energy of 32,000,000 J/k*g.
Taking several days to mean 4 days or 345,600 seconds that m*eans
the power source has to supply 92.6 W per kg of airship in o*rbit.


Now using data from Larsen and Pranke an ISS 890 kg photovol*taic
blanket produces 28000 W for a specific power 31.5 W/kg.


So even if the airship were nothing but photovoltaic cells
converting electricity to kinetic energy at 100% efficiency *it
couldn't possibly achieve orbit in several days even ignorin*g
atmospheric drag.


Surely the folks at JP Aerospace can do this simple calculat*ion. So
what am I missing here?

Jim Davis