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 | | From: | Greg Gauthier | | Subject: | Re: Mars Rover Controlled By Java | | Date: | Tue, 04 Jan 2005 20:22:56 -0600 |
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 | This is all remarkably fascinating!
Just one question:
What does it have to do with Java?
Thanks,
Greg
Edward Green wrote:
> Uncle Al wrote in message news:<4009BB55.4CCD266E@hate.spam.net>...
>
>>mitch wrote:
>>
>>>Uncle Al wrote:
>>>
>>>>Local atmospheric pressure is 7-10 torr. Earth sea level is 760
>>>>torr. How many planes do you know that cruise at 100,000 feet absent
>>>>any oxygen at all? Martian aircraft are a bad dream.
>>>
>>>Hmm. Then the test of a Mars glider plane back in August of 2001 was
>>>just a bad dream? ;-) Work has begun on a propellered version of the
>>>glider cited below. Enjoy.
>>
>>
>>
>>>AMES COMPLETES SUCCESSFUL TEST OF MARS AIRPLANE PROTOTYPE
>>
>>The empirical fact is that lowland Martian air pressure is 7-10 torr.
>>The is equivalent to 120,000-100,000 feet terrestrial altitude.
>
>
> Read the article: the glider was released at 101,000 feet.
>
>
>>If
>>the silly thing will be diddling at even 1000 ft altitude Martian, the
>>air will be thinner.
>
>
> Martian gravity is less, hence the pressure relative pressure
> difference between 0 and 1000 feet will be less than that on Earth:
> less than 5%.
>
>
>>"Ye canna break the laws of physics."
>>
>>The Concorde flew at 60,000 feet and gulped air like a madman. The
>>U-2 did 75,000 feet, breathed air, and it was a bitch to fly. The
>>SR-71 Blackbird could barely do 100,000 feet while at Mach 3+ with its
>>cockpit windshield simmering at 620 F. It drank 8000 gallons/hr of
>>fuel. It breathed 6 million ft^3 of air/minute.
>
>
> Al ... organizational bashing is fun and rewarding, but must be taken
> with up with taste. Sending flawed subtly mirrors into space while
> good ones sit in storage, and launching on colder and colder days
> until disaster strikes: these are both errors of judgement well within
> the capability of the political machine. But making fundamental
> science errors in the preliminary design stages, and saying something
> (whose gross design parameters are available to anybody willing to
> take the time to look) can work when it not only can't but, according
> to you, grossly can't?
>
> That is down at the 5 sigma tail of Bayesian probability, and you know
> it.
>
> Of your three examples, only the U-2 is remotely relevant, since it
> was essentially a powered glider; and it did not gulp air and fuel,
> which you seem fixated on. Who the hell said anything about
> air-breathing flight, anyway?
>
> The basic principles and parameters are well known: you have your
> Martian atmosphere, you have your structural requirements, you have
> your power requirements, you have your known solar cell efficiency.
> The engineering either comes together or it doesn't. Have you run the
> figures? The issue is whether you can build a large enough and light
> enough airframe to move enough rarefied gas to generate sufficient
> lift to sustain flight at a drag sustainable by some reasonable power
> make-up from solar cells. There are people who could do this on the
> back of an envelope.
>
> No ... I haven't run the calculations either. But knowing that high
> altitude long dwell time solar powered sail planes have been seriously
> considered on Earth, that flight costs less power with slower flight
> and larger lifting area, knowing the experience with very light weight
> miniminally powered structures accumulated by the human-powered flight
> school ... all this give credibility to the idea and tends to suggest
> that Al is making an ill-considered shot from the hip, as usual.
>
> And this is not to mention aerostats ... you may have noticed also how
> the test glider was carried to 101,000 ft? I suppose that was a
> physical impossibility too?
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