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Is there a way to calculate the gliding distance for a remote controlled (RD) jet aircraft, in case of engine failure? We have some telemetry data on the model, giving us speed and altitude so as to plug them on an equation or other model in estimating the glide distance, but we would not want to actually risk destroying the jet by testing a real life scenario.

So, for example, our maximum allowed altitude is 500ft Above Ground Level and its speed is about 150 knots; we are interested in calculating the gliding distance if engine power is lost or cut off (the engine is automatically cut off if the jet flies outside radio control range).

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    $\begingroup$ You need to be a little more specific - what is the aspect ratio, wing shape, fuselage size etc. This would allow to estimate the drag, which is a necessary part of calculating lift/drag. This ratio will give you the glide ratio. $\endgroup$
    – Peter Kämpf
    Mar 28, 2015 at 7:26
  • $\begingroup$ I don't see the risk in testing. Set it up ok a nice day, cut the engines, measure the glide, and restart the engines at, say, 100ft AGL. $\endgroup$
    – raptortech97
    Mar 28, 2015 at 22:04
  • $\begingroup$ Hi Peter, thanks for your answer. Assuming you have the quantities described above, it the computation straight forward or does it involve numerical analysis? I remember back in my grad school days we used Galerkin procedure to solve a number of differential equations, but it completely escapes me now.....is that what you are referring to? $\endgroup$
    – user2990492
    Mar 30, 2015 at 14:14

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I think the only way is to test it.

Choose a day with very calm wind.

Set the plane up for fixed speed anywhere between obviously-lower-than-best-glide-speed and obviously-higher-than-best-glide-speed, and make multiple tests with incrementing the speed in small steps (like 5kt). You can probably think out the details of the experiment yourself, but this should work well.

It's very difficult to compute these things. Companies like Airbus or Boeing have (probably proprietary) software for this, large clusters, etc., perform test in an aerodynamic tunnel and do many test flights. Since you likely don't have all the equipment, the only thing you can rely on is the test flight.

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  • $\begingroup$ thanks for your response; I believe that the best way to measure it is through tests (using max and min speed reference boundaries as you indicate). $\endgroup$
    – user2990492
    Mar 30, 2015 at 13:55

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