Okay, We've all heard things like "it flys scale like", "it's faster than scale", "flies on the wing", and let's not leave out "flies like a brick". But how fast does the average RC Plane fly? Is there a way to gauge the speed of our creations? Is there a comparative between actual speed of the model and the scale speed of the real thing?

Happy Flying

Loopman

It's harder to define "average" nowadays than it used to be. Most typical models can hit between 80 and 120 mph. For speed you want to find the smallest diameter, highest pitch prop combo that pulls the plane the fastest. If you experiment with not enough diameter, there wont be enough thrust to safely fly the plane, so experiment by making gradual changes. The overall performance of the model can suffer enough to make you quit your search for the best speed prop for your plane.

120 on average... the median between 40 and 200 mph....

I would have to say an average speed at any given field on a Sunday would be around 70 mph. Yes there are airplanes that are capable of 200 mph but those are very few and far between. At your average club anything over 110mph is considered quite fast. Most stock built kits and ARFs will self destruct over 130 mph. Anything faster then that usually requires that the airplane be built capable of those speeds. Airframe strengthening, airfoil changes, streamlining ect.

As far as scale speeds are concerned, IMO most scale models are flown too fast. Take example of a 1/5 scale Cessna. The model can be flown around at between 40 and 50 mph. Most would actually fly it faster. Now doing the math, that 40 mph turns into 200 mph scale speed. Now that's a fast Cessna. The other side of that coin is a 1/7 scale F-16 being flown at 150 mph. That translates into 1,100 mph and that is more in line with the jet.

There are far too many variables at play plus scaling effects to draw any general correlation between a full scale aircraft and a scale model in terms of flight regime. Generally models have to be built with very light wing loadings to fly at anything resembling realistic scale speeds. Linear dimensions scale proportionally, areas as the square of scale, volumes as the cube. Reynolds numbers go down so efficiency suffers.

Using a familiar example to me, a Tiger Moth might cruise at 75mph and they stall at about 45. Build a 1/7 scale version and it would have just over 4' wingspan, cruise speed would be 10.7 mph and stall at 6.4 mph. Now think about the weight and construction techniques required to build a 4' span model with those characteristics!