Re: Venus Air****ps / by Brad Guth

[posted and mailed]

BradGuth <bradguth@[EMAIL PROTECTED]
> wrote:
> Thanks for all of that constructive and somewhat outdated though
> informative but also some of that rather silly balloon s****t feedback,
> much of which I've seen dozens of times before.

The "Air****p Technology" text is about as recent as they come in that 
field. And the basic science hasn't changed (though the available 
technologies have changed), so the older works are still applicable too.

As to the "silly balloon s****t" part - approached correctly, such people 
may be a good bet in terms of finding helpers and collaborators.

> Once again, seems folks expect little old me to accomplish 100+% of
> everything.

I do know that when I come up with an idea, I fully expect to do 100% of 
the work in making it happen - or at least develop it to the point I can 
"sell" it to others in terms of persuading them to help. I think you need 
to realize that basic fact of life. You can't on one hand be critical or 
contemptuous of the help of others if it less than what you desire, and 
yet on the other hand have an expectation that those same people should 
be doing the legwork you need to do. Okay - you could. But it'll backfire 
for sure.

In any case, I just gave you maybe a 50% headstart, depending on how you 
count knowledge. Almost everything you need to know to design and build 
an air****p capable of flying in the atmosphere of Venus is in the 
reference materials I provided.

> You do realize this is not an inflated balloon application, as
> proposed by Yavrouian, not that efficiently ballooning science
> instruments below them thick clouds isn't technically doable,
> especially on behalf of the micro electronic packages that involve so
> little mass and require such little energy as they outperform their
> task in most every aspect.

I fully realized that you did not intend to use an inflated balloon. I 
expected, though, that suitable envelope material would be needed to 
survive the high temperatures and conditions of the Venus atmosphere. The 
paper in question already did some legwork and concluded that PBO was a 
viable candidate. I thought you'd find the information useful. If not, 
sorry I tried to provide info I had at hand.

> Starting from scratch, this rigid composite air****p is capable of good
> size and substantial payload, and its going to be like nothing ever
> before utilized on Earth or any other planet.  The closest analogy of
> anything terrestrial is going to be a nuclear submarine, whereas
> instead having its Venus buoyancy created by either a vacuum that’s
> easily managed by getting pumped out, or merely displaced from the top
> down with the failsafe gas of hydrogen.

1) Use of a rigid air****p seems implausible - where would it be 
constructed? If on Earth or in Earth orbit, it seems absurd to attempt to 
launch such a bulky object to Venus, and then somehow attempt to de-orbit 
it undamaged into the Venus atmosphere. Building it on Venus would seem 
to require an even larger logistic effort. An inflatable pressurized 
envelope seems the best bet. The envelope could be easily stowed in 
compact form.

2) Using a vacuum for buoyancy is a classic bad solution - mostly because 
the envelope walls and sup****t structures turn out to be so heavy that it 
can never provide buoyancy with currently available materials. And the 
gain relative to, say, H2 or He is only a few percent! The best 
alternative internal sup****t currently available is another, less dense, 
gas. Since venus is ~97% CO2, and the molecular weight (MW) of CO2 is 44, 
any gas less than that MW would provide buoyancy. Water (H2O) has a MW of 
18 so it should work fine (steam even works on Earth, whose atmospheric 
MW is ~29). I'd suggest that rather than hydrogen. Venus' atmosphere has 
a density of ~65 kg/m^3 at the surface, so:

density_lift_gas = density_atmosphere*(lift_gas_MW/atmosphere_MW)
buoyancy = air****p_volume*(density_atmosphere - density_lift_gas)

Therefore:
buoyancy =
  air****p_volume*density_atmosphere*(1 - lift_gas_MW/atmosphere_MW)

So:
buoyancy = air****p_volume*38 kg/m^3

That's fantastic buoyancy - by comparison the maximum theoretical value 
for buoyancy at the surface of the Earth (using the classic "vacuum"; 
i.e. lift_gas_MW = 0) yields:

buoyancy = air****p_volume*1.2 kg/m^3

By the way, if you set lift_gas_MW to 0, 2, and 4 (vacuum, H2, and He 
respectively) and atmosphere_MW to 29 or 44 (Earth or Venus, 
respectively) in the above equations you'll see that a vacuum doesn't 
gain you that much more lift, percentage wise, than that provided by H2 
or He.

>  I was thinking along the
> lines of using rigid/hard composite spheres, arranged into an air****p
> format (5 in tandem) that’s kind of aerodynamically suited to the task
> at hand.  This requires more than a simple balloon, especially if
> active navigation is incor****ated.

That seems needlessly draggy and aerodynamically unstable.

Anyway, this is the last bit of suggestions I intend to provide. I have 
my own projects to work on. Good luck.