posted on Oct, 2 2014 @ 12:39 AM
originally posted by: JiggyPotamus. One of the main components would be the outer shell, some type of coating that could
withstand the increased temperatures of supersonic flight, which would reach hundreds of degrees F.
You have to be going quite fast for aerodynamic heating generally. Mach 1 at 30,000' is probably going to give you a surface temp somewhere around
60F (air temp at 30,000' is around -55F, so aerodynamic or kinetic heating is being absorbed by the airflow).
Some of that depends on altitude (or density of the air). Some of that is going to depend on the shape of the airframe. The more the shape slows the
airflow as it contacts the surface area, the more heat is built. Some of the heat is going to radiate through the airframe. We could design our fuel
tanks to absorb some of that heat at the leading edges of the wings, for example, to catch more heat.Some will radiate back into the air.
It's also proportional to the square of the airspeed, so it is going to build up quickly. A rule of thumb is, if you slowed the air at sea level 100%
(and you won't even with a brick shape), you would increase the temp by about 100C at 1000mph (Mach 1.3). That's below the burning temp of wood,
though we might get some smouldering at the nose and wingtips. At 2000mph (Mach 2.6), we're up to 400C. Now we've got problems even with most
metals. At 3000mph (3.9M), we're at 900C.
Now those numbers are at sea level, and no one generally goes that fast at sea level because the air is thicker (drag, and kinetic heating) and warmer
there. We'd probably only get about 85% of that heat at the hottest parts of the airframe because of aerodynamic shaping. Going to a higher altitude
is going to help because the air temp is a lot colder at altitude, and the density/mass of the air is substantially less. The SR-71 experienced
"only" about 240C heating at cruise at very high-altitude. Plenty hot enough to destroy wood, but also going three times the speed of sound.
Wood would be fine temp wise at Mach 1.1. Structurally, you're going to take a beating in transonic flight just from the turbulent airflow over the
structure. But not heat.
So could it be done with wood? Sure, if we make the airframe strong enough to pass through the transonic state, and we do it at altitudes higher than