<VV> Gas freezing?

[Jim Davis]

The *environmental lapse rate* (ELR), is the rate of decrease of 
temperature with altitude in the stationary atmosphere at a given time 
and location. As an average, the International Civil Aviation 
Organization 
<http://en.wikipedia.org/wiki/International_Civil_Aviation_Organization> 
(ICAO) defines an international standard atmosphere (ISA) with a 
temperature lapse rate of 6.49 K(°C)/1,000 m^[/citation needed 
<http://en.wikipedia.org/wiki/Wikipedia:Citation_needed>/] (3.56 °F or 
1.98 K(°C)/1,000 Ft) from sea level to 11 km (36,090 ft). From 11 km 
(36,090 ft or 6.8 mi) up to 20 km (65,620 ft or 12.4 mi), the constant 
temperature is -56.5 °C (-69.7 °F), which is the lowest assumed 
temperature in the ISA. The standard atmosphere 
<http://en.wikipedia.org/wiki/ICAO_Standard_Atmosphere> contains no 
moisture. Unlike the idealized ISA, the temperature of the actual 
atmosphere does not always fall at a uniform rate with height. For 
example, there can be an inversion 
<http://en.wikipedia.org/wiki/Temperature_inversion> layer in which the 
temperature increases with altitude.

I used to compute ballistics for B-58A.  (66,000 ft @ 1,150 nm/h)   This 
is a rough estimation of the tables we used.

Jim Davis

On 12/25/2013 6:47 PM, J. R. Read wrote:
> Sorry, I'll try to be more clear on my calcs.  Starting with 70F at sea
> level and using the "rule of thumb" (strange expression) of a drop of 3F for
> each 1,000 feet of altitude, the temp at 50,000 feet would be around -80F.
> >From sea level to 50,000 at 3F per 1,000 feet the temp will drop by 150F or
> so.  Subtracting the 70F at sea level, you end up at -80F at 50,000.  If the
> rule of thumb is off a bit from the 3F drop, then the appropriate adjustment
> needs to be made.
>
> Once again - not a real likely altitude for a piston engine, but even 20,000
> feet would give you a temp around +10F and little air for breathing or the
> engine.  I think that we are in agreement that freezing fuel would not be
> the main problem.
>
> Later, JR
>
> ----- Original Message -----
> From: <aeroned at aol.com>
> To: <virtualvairs at corvair.org>
>
> Sent: Wednesday, December 25, 2013 12:30 PM
> Subject: Re: <VV> Non-Corvair Specific: Gas freezing?
>
>
>> OK JR, at 50000 feet it's -69F not quite -97 or -80 but I suppose it's
>> close enough?
>>
>>