its open circuit wind tunnel , we have a modeled aircraft bede bd-5
problem is balancing the aircraft and L/D ratios at different of attack , so which kind of mechanism could used?
Prad,
You need to give more details, before a good answer could be given, especially on the method(s) and the instruments involved.
But generally, in wind tunnel tests, you could get the values of the forces by 2 main methods (there are others of course). Firstly, measuring the forces directly, and secondly measuring surface pressures and integrating it over the corresponding surface areas. Of course the first is the most preferred, as it is the direct method: which is the main reason (raison d'etre) of doing the wind tunnels tests.
Wan Zaidi
Ssir,
our college have surface pressure measuring systems but it is not very accurate due to some defects.so i am prefering to use any kind of force measuring system.
So i am trying to find out the methods to measure lift and drag simultaneously while changing angle of attack of the whole model aircraft.
Easiest way is to resign from the requirement that both aerodynamic force components have to be measured at the same time. If you can set - or measure efficiently - the angle of attack, you can do both scans: for lift and for drag, separately. Then I'd rather suggest to make third, a pitch moment test also. Soon it will be necessary, since the lift center is not in constant place. The model has to be mounted one wing down, that way the gravitational forces will not influence the results for moment measurements. Well, you can always buy a 3-component tensometric balance, mounted inside model or on a sting, or try to make your own balance, you will learn also how to glue the tensometers, which could be a useful knowledge :)
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