The equation you have given is for incompressible fluid.While it works at low speed,it completely fails at high speed ant to the extent that some properties of fluid simply become exactly opposite to what they are at low speeds.
Compressibility could have large effect on fluid mechanics of objects.An RC model's flight does not prove anything.
Fluid flow is divided in three categories conventionally and five contemporarily.
1.Incompressible flow : less than Mach 0.3 at which your equation is true.
2.Compressible Subsonic: Mach 0.3 to Mach 1
3.Compressible Supersonic: Greater than Mach 1
See page 28 and 38 of attached tutorial.
http://www.taiwan921.lib.ntu.edu.tw/mypdf/fluid11.pdf
@
salman108
While the flight of an RC model proves nothing,flight of a scale model in wind tunnel is enough to prove feasibility of a design.It is not dependent on Size.
The so called plane has a long list of shortcomings which put into doubt the very probability of its self powered flight starting with being not large enough to house a decent engine,air uptake ducts which are neither big enough to sustain high altitude and high speed flight and would choke engine completely at high AoA,lack of weapon bay and design of aerofoil which would produce very poor lift for given thrust.
The flight of an RC model is not indicative of design integrity.It is unpowered subsonic flight.
In an unpowered flight,you could make a piano fly.The jet if Iran persist could get airborne but it would be a limping lightly armed subsonic jet having rate of climb worse than a cessna and with dubious stealth characteristics.
@
Era_923 and @
Mosamania
You people should go a little light on censorship.Half of the post in any thread related to middle east are deleted and people receive infraction for advocating PoV of their countries( I am talking about Syrian issues).People are not juvenile that their fragile sensitivities should be respected.Only outright abusive posts need deletion.