Cheap Space Flight for Everyone by Bob Freeman

[deleted]

Tommy,

Thanks for your interest in the project.

Took a look at rockoon web page and it looks like a great system, but it is still just using conventional rockets with a pre-lift using balloons.

I'm proposing that the balloon be part of the lift packet for use later as storage or solar sail

It would require a "mast" structure for the balloon to be wrapped around and to pump the hydrogen down to the H2+O2 rocket.

JP's Aerospace to Airship Orbit is also a great concept, but requires extensive engineering and support while the system we propose is just a simple extension of current high altitude balloons.

This will make it available to smaller players in the market without the support of large government engineers, not that this is a bad way to do it.

In any case, the more systems we have the better, to find one that works best.

I've also outlined a few other issues on how a "slow" lift system works compared to explosive rocket designs at www.h2liftship.com

Bob

Tommy Anderberg

I had a look at your site, but did not see any attempt to calculate anything. The closest thing I could find to a description of the proposal states that

The boost crew compresses the hydrogen using compressor pumps on treadmills while the balloon is re-configured, supplying thrust to boost the ship from the grip of gravity.

So people running on treadmills are going to provide enough power to keep themselves and the ship airborn, plus excess power for the compressors? Given the state of human-powered flight, this seems a tad optimistic.

Have you tried to compare (1) the amount of hydrogen required to lift a balloon carrying some payload into the stratosphere to (2) the amount of hydrogen required to fuel a rocket capable of bringing the same payload to LEO? The volume of a high altitude balloon is huge, but its density is quite low (after all, that's why it flies). A rocket is the other way around; large mass in a small volume.

Bob Freeman

Tommy,

You are right, there are no calculations, it is designed more as a concept that needs more exploration.

We really don't know if microgravity at higher altitudes would reduce the amount of lift required or if the small amount of solar wind could be used as a slight push at higher altitudes.

These small items could make a the difference between success or a spectacular failure.

These can only be discovered if an attempt is made using the H2lift balloon.

Calculations can prove that it can't work, but experience could show that it may, and where is the fun if you prove it is impossible and never try?

The site (www.h2liftship.com) also presents the concept as a "scifi" story, that is still not complete (having trouble finding the time to devote to polishing it up since regular work seems to demand my time). SciFi allows humans, dogs and monkeys to be part of a launch sequence, reality has some different answers.

Again, thanks for taking the time to review the web page and information

Bob

Tommy Anderberg

You won't get microgravity at the height reachable by balloon. The altitude record is something like 53 km. Gravitational acceleration is inversely proportional to distance squared, so the ratio between sea-level and balloon-record-altitude acceleration is roughly (1 53/6370)^2 (using 6370 km for Earth's radius). The difference is less than 1.7%.

You can find the formula for acceleration attainable by a solar sail operating at the Earth's distance from the sun on Wikipedia. Note the units: millimeter per second squared. It is orders of magnitudes less than you'd need for orbital maneuvers, even disregarding that Earth's magnetosphere deflects most of the solar wind at higher altitudes (when it's disrupted, you get aurora at altitudes of 80 kilometers and more, and mainly around the poles, where the magnetic field curves into Earth's surface).

As for "the fun if you prove it is impossible and never try", it might be a plausible argument in unexplored territory, where the theory is untested, but there is nothing special about the altitudes and physics involved here.

[deleted]

Bob,

It seems unbelievable but futurists have spoken of an elevator to a geocentric satellite some 22,000 miles above us. I thought of this as you describe methods of reaching space, sort of the last frontier.

In my essay I speak of "Looking beyond" in terms of Earth and orthodox science. I would like to see your views on my essay.

Jim

Bob Freeman

Jim

Glad to look at it, where is the essay located?

Bob

James Hoover

Bob,

http://www.fqxi.org/community/forum/topic/2008.

Regards,

Jim

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