At 10:31 PM 31/01/2007, you wrote:
On Wed, 2007-01-31 at 19:19 +1000, Mike Borgelt wrote:
> At 05:52 PM 31/01/2007, you wrote:
> >Good work Ken.. Reminds me of the time you worked out that a Ka6
> >could not fly above 96,000 feet because the Vne equaled the stalling
> >speed.. good memories from 40 years ago. :)
> >
>
> I suspect the limiting mach number would make
it somewhat less than 96000 feet.
I cannot recall how I arrived at the number I did (whatever it was) but using
the calculator at
http://www.digitaldutch.com/atmoscalc/ I see that at 103000 ft
the air density is 0.014518 kg/m**3 and the speed of sound is 302.729518 m/s
Assuming a stalling speed at ¨sea level¨ of 16.5 m/s the stalling speed
at 103000 ft would be sqrt(1.225/0.014518) times 16.5 or 151.6 m/s
0.5 M may be below the critical Mach number for the Ka6 but goodness
knows at what speed the aircraft would start to flutter.
In any case I doubt that you could get into the cockpit in a space suit.
> If you want to be really fussy about the water column you should
> correct the density of the water for temperature.
>
True
cheers
Ken
I think the Perlan project guys figured the
limiting Mach of the DG500 is around 0.5.
I've heard 63000 feet is the safe ceiling.
3 years ago we had a former U2 and SR71 pilot
speak at our 100th anniversary of flight EAA dinner in Toowoomba.
Later U2s had much better margins. Earlier models
had around 4 knots IAS of safe band in cruise.
For a good read about what the SR71 was like read
Brain Schul's "Sled Driver" and "The Untouchables"
In the latter book he talks about the post strike
recon the day after the 1986 Libyan strike.
They went in over the coast at about 79000 feet
and Mach 3.2 and then pushed the throttles up a bit!
Later when going faster they opened them all the way.
MIke
Borgelt Instruments - manufacturers of quality soaring instruments
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