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Hello friends!
I want to figure out how much friction drag these little rc airplane wheels create during the take-off run. I suspect it detracts more from our engines than the aerodynamic drag! Has anyone experimented with it?

Cactus.

My Feedback: (1)

depends if you do your collets too close to the wheel hub, best to let them free wheel, use a bit of card as a spacer. the drag on take off is better than ballracing the wheel with the extra weight all flight. infact... if you can take off fine, but dont slow down on landing you can add a bit of fuelk tube between the collet and wheel to cause friction to slow the roll out. take off isnt effected tooo much.

another point if you have grass runways, the wheel should be at least twice the height of the grass. helps it ride over the grass

swill

My Feedback: (17)

here are some equations to get you started and a short discussion:

The acceleration of an airplane on the ground can be determined by knowing the forces involved - Lift (L), Drag (D), Thrust (T), Weight (W), rolling friction (Ff) and Runway Slope (RSL). Since the tangential force retarding the motion of a moving body is proportional to the perpendicular, or normal force, the relationship may be written:

Frictional Force = u * Normal Force
Frictional Force = u * (W - L)

where the normal Force is the difference between the weight of the aircraft and the lift the wings are producing. In the airplane business we generally use u = 0.015 for rolling conditions on dry concrete, so the retarding force will be about 1.5% of the weight on the wheels at any given time.

Force = Mass * Acceleration

For a takeoff (ground roll acceleration) we have:

Thrust - Drag - Brake/Friction Force - (force due to slope of runway)= Mass * Accel