Aerosoft Aerosoft Team [Inactive Account] 51558 Posted December 23, 2009 Aerosoft Share Posted December 23, 2009 Getting closer to Christmas, so let's do an easy one... We all know the fuselage of high speed aircraft like the SR71 heats up a lot in flight. So much it needs to be made from special metals. But what actually causes most of that heat? Link to comment Share on other sites More sharing options...
LN-MAG 9 Posted December 23, 2009 Share Posted December 23, 2009 The friction between the fuselage and the surrounding air. Also known as air drag. Link to comment Share on other sites More sharing options...
Alexander Wurz 42 Posted December 23, 2009 Share Posted December 23, 2009 jep the friction between air and the fuselage and when you travel at high speed like the old blackbird, the friction grows really high which causes actual more heat on the fuselage than in a normal airliner Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted December 23, 2009 Author Aerosoft Share Posted December 23, 2009 The friction between the fuselage and the surrounding air. Also known as air drag. Well, the friction of the air on the skin IS a factor, but it actually is a minor one. There is another, far more important effect that causes the heat. Surprised? It's true! Link to comment Share on other sites More sharing options...
LN-MAG 9 Posted December 23, 2009 Share Posted December 23, 2009 And it also causes the fuselage to expand, but the SR-71 was designed with this expansion in mind. When on the ground, it actually leaked fuel because the parts were made to fit when they were fully expanded Link to comment Share on other sites More sharing options...
Carlos Domingos 4 Posted December 23, 2009 Share Posted December 23, 2009 Well, this is also related to air friction but the air in front of the aircraft is compressed into a supersonic shock wave, and the energy generated by this heats the airframe. Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted December 23, 2009 Author Aerosoft Share Posted December 23, 2009 And it also causes the fuselage to expand, but the SR-71 was designed with this expansion in mind. When on the ground, it actually leaked fuel because the parts were made to fit when they were fully expanded But WHY does it heat up? Link to comment Share on other sites More sharing options...
Aerosoft Aerosoft Team [Inactive Account] 51558 Posted December 23, 2009 Author Aerosoft Share Posted December 23, 2009 Well, this is also related to air friction but the air in front of the aircraft is compressed into a supersonic shock wave, and the energy generated by this heats the airframe. Bingo, it's the compression of the air that creates most of the heat (about 80%), not the drag. When you compress air it's temperature rises, that's why your bicycle pump gets so hot when you pump your tires. Does not have a lot to do with shock waves and this effect is not directly related to air friction btw. Link to comment Share on other sites More sharing options...
Carlos Domingos 4 Posted December 23, 2009 Share Posted December 23, 2009 ...Does not have a lot to do with shock waves and this effect is not directly related to air friction btw. You're right! And I shouldn't have made such mistake, well if my boss don't find out I'll be ok anyway . Link to comment Share on other sites More sharing options...
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