Superman Protagonist: Skinsuit Capability Up to 4,000mph

[chasrob]

I have as a protagonist a being like Superman, except transformed from your average human. After the transformation, some advanced aliens presented him with a skinsuit to wear as he is flying about, so he can avoid traveling in his birthday suit. It can withstand the heat, forces, etc., at a velocity of up to 4,000 mph at sea level. Extrapolating for lower air pressure, what speed can it handle at 16000 feet? At 50,000 or 70,000?
Underneath the skinsuit, he can wear regular clothing, without it wrinkling, which is even more miraculous (;.

 

[256bits]

One way is to set a maximum speed for him in space, such as say V_max, say 50,000 mph.
Then make an assumption that his speed depends upon the density of air.
Then utilizing the air density correlation with altitude ( a search and you will find some information on this ), one can determine his speed at that altitude.
Make a graph of speed vs density, and you can then pick off the altitude points and label them on the graph at the matching density to get his speed.

That's not entirely correct though since we did not take into account how drag depends on speed - the faster he goes the more drag, and since he most likely has a maximum power output, this again limits his speed through a medium. In fact, the drag is going to depend upon his velocity squared. One can see that to achieve the same speed as he did from the above graph, the density has to much less. Double the speed, decrease density by 4. Triple the speed, decrease density by 9.

Of course, one can see a sticky point. In space where friction is quite negligible, by him outputting power continuously, he would accelerate to a much greater velocity than the first proposed V_max. Maybe the aliens told him that if he goes faster he turns into a mushroom :).

since the guy is supersonic,
You can read some interesting prose about supersonic in a series,
https://leehamnews.com/2018/02/09/bjorns-corner-aircraft-drag-reduction-part-16/
https://leehamnews.com/2018/08/17/bjorns-corner-supersonic-transport-revival-part-2/

Especially note, in series 16,

The volume drag of a needle body, like in the picture, is proportional to the inverse square of the body length divided by its diameter. The body length divided by the diameter is called the fineness ratio of the body.

The guy is quite blunt - his fineness ratio is about 3.
Volume drag, wave drag, which I haven't talked about, would predominate for our hero.
You can work that in also after reading up on the subject.

 

[chasrob]

Thanks for the interesting links. The character, as written, has the basic powers of Superman--flight, invulnerability, super strength, super speed, but to an insane degree--so physically, keeping it as simple as I can. Speed up to 100,000 miles/second (.54c) and he can fly through any environment as if it were thin air, with no ill effects. Even through a neutron star. In a chapter, he tunnels through the Earth (to escape stalkers undetected); he comes out at the antipodal point .1 seconds later. In the Indian Ocean west of Australia! 'Tho he had to fly home in the nude since his apparel didn't survive. He doesn't fly at that speed through atmosphere, where it would trash the landscape, but in interplanetary space...

His problem is he didn't acquire Big Blue's super-spandex, and although no one would call him a prude, flying around in the altogether is not his style. So he talked these advanced aliens into fashioning a skinsuit similar to scuba suits--open at his head and hands. The aliens put the 4k limit on the construction however. He can even fly that fast in a vertical position (a very poor fineness ratio I imagine), which is that more difficult on his suit, but it can handle it. Plus no sonic boom, and its stealthy to radar besides. (:

Even at 4k mph the Earth is, well, a big place so he uses this schema to get anywhere even faster, say USA to Europe--

I figured about a minute to get up to 75 miles, but then I had the idea that he could go even faster as the air thinned at higher altitudes... that's why I asked.

 

[anorlunda]

If modesty is the only point, how about a hologram projection of a virtual suit. Then there is no need to worry about how tough a real suit would be.