If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
For Lennie - soaring on Mars
The pressure difference across a thin vertical slice in a fluid is
dP = rho x g x dh where rho is density, g = acceleration due to gravity, dh is the vertical thickness of the slice. So by rearrangement we get dP/dh = rho x g dP/dh is the vertical pressure gradient(rate of change of pressure with altitude) So where the density is low the rate of change of pressure with altitude is low - this in fact is what happens in the Earth's atmosphere. Also where g is low the same applies. So on Mars where g is about 0.38 of Earth and the surface density is low (about 1% of Earth) the vertical pressure gradient is low. The density of a gas also depends on its absolute temperature but vertical temperature gradients are limited to dry adiabatic or thereabouts except for short periods(you get convection which then ensures dry adiabatic by mixing - assuming no condensation). This does mean that the density with altitude doesn't drop off as fast as the pressure with altitude which I've just shown is much slower than on Earth so the conclusion is that if your Mars airplane can fly at all at the Martian surface it will probably have a useful operating ceiling. No astrophysics required, just freshman physics 101 and a little meteorology. Mike Borgelt (B.Sc Physics, post grad Diploma meteorology) |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Advanced Soaring Seminar - Eastern PA | B Lacovara | Home Built | 0 | February 9th 04 01:55 AM |
Advanced Soaring Seminar - Eastern PA | B Lacovara | Piloting | 0 | February 9th 04 01:54 AM |
September issue of Southern California Soaring is on-line | SoCalSoaring | Soaring | 0 | September 11th 03 08:10 AM |
Soaring on Mars | puffnfresh | Soaring | 21 | September 3rd 03 11:24 AM |