Skin Temp
Skin Temp
(OP)
I am not in aircraft design, but this looked like a good place to ask the question. We were flying to Armenia and we reached an altitude that I had not flown at before 44,000 or so. The ambient Temp -82 Celsuis at a speed of 680 MPH. What is the approx. skin temp (wing and/or fuelage) at that speed and temp.





RE: Skin Temp
Take a look at the above calculator. For standard conditions temp at 44,000 feet is -69 degF. You stated 44,000 feet at -82 degC which is -115.6 degF. Are you sure about the temp? For standard conditions at 44,000 feet your speed of 680 mph would be slightly over Mach 1. Are you sure the speed is air speed and not ground speed? What were you flying in?
RE: Skin Temp
If you were looking at an Airshow map (airplane symbol on world map) in the passenger cabin, you would have seen ground speed as the speed number, and 680 mph would be reasonable.
The airspeed would have most likely been around 325 to 350 KIAS (indicated airspeed) if you were looking at a flight deck airspeed indicator. If you were on the flight deck and saw an indicated airspeed of 680mph (unlikely since they are in knots) you would have lived about 1/2 second before the aircraft disintegrated.
If you were in a military aircraft that IS capable of 680 mph at 44,000 feet, you are probably not supposed to be talking about it. (he he, some humor there)
debodine
However, I don't know the skin temperature formula.
debodine
RE: Skin Temp
Sorry to hit send before I was done,
debodine
RE: Skin Temp
RE: Skin Temp
TTFN
RE: Skin Temp
The stagnation, or total, temperature "is the temperature of the airflow at a stagnation point, such as the leading edge of the wing or nose of the aircraft." But, I'm still uncertain of the remaining skin temperatures.
So, aero guys, is this 'total' temperature the maximum skin temperature on the aircraft? Does a skin temperature continuum between -69oF and -5oF exist for this aircraft depending upon surface flow?
There should be less heating due to air friction at a stagnation point. Some heat is generated by turbulence within the air. But, of course, also less convective cooling.
Answers?
RE: Skin Temp
TTFN
RE: Skin Temp
htt
At a stagnation point, the air velocity is reduced to "zero", converting all of the kinetic energy to heat. At hypersonic speeds, the temperature change is tremendous. At sub-sonic speeds, it is measurable, but hardly an issue.
Steven Fahey, CET