3 ms·
That is coefficient of drag. You have to remember that goes into the drag equation which includes velocity squared. force_of_drag = .5 * mass_density * (veloc
by lujim 10y ago
That is coefficient of drag. You have to remember that goes into the drag equation which includes velocity squared.
force_of_drag = .5 * mass_density * (velocity^2) * coefficient_drag * area.
As that coefficient starts tapering off after transonic drag decreases velocity squared is there to ramp up the drag.
- mchouza 10y agoThat's true, but supersonic planes also travel higher (Concorde -> 18 km, XB-70 -> 22 km). The real problem is that L/D decreases at supersonic speeds. For example, the XB-70 had a L/D of about 7, while the 707 had a L/D over 18...
- Gravityloss 10y agoAs lift is also proportional to density, area and square of velocity, that whole term cancels out from the equation of fuel usage per distance, basically only L/D or cL/cD matters. In practice it might be a bit more complicated. EDIT: indeed here we can see that Concorde had lift to drag ratio of only 7.5 at Mach 2, while Boeing 747 has 17.7 at Mach 0.9 or so. https://en.wikipedia.org/wiki/Lift-to-drag_ratio https://en.wikipedia.org/wiki/Lift-to-drag_ratio
- DrScump 10y agoBut you should also factor in their comparative passenger capacities (e.g. impact per passenger-mile).
- Gravityloss 10y agoPerhaps better would be aircraft weight to number of passengers ratio. Revenue wise the supersonic airliner flies faster, meaning you get more seat miles per day per seat.