The only thing I can see is that the fuel should be supplied on the day from a common jug and pump to the flyers on the start line.  That'll avoid any "creative" fuel issues.  Other than that if the engines all sound more or less equal then it must be the flying ability of the fast guys.  Flying a tight and efficient course with the turns tight but not too tight where it slows down the model too much from drag in the turns will go a huge way towards making a given flyer faster over the next guy.

Even on the fuel issue if you can't hear a big disparity in exhaust tones from the fast models then it's gotta be the flyer and not the model.

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ORIGINAL: RCfan

The only indication is that the engines of the faster airplanes are turning over 15,000 rpm with the APC 7x4 prop. The rest of the field seems to get barely 14,000.

Ya know, I  like the idea of a tach before flight rule.  But since results can vary from day to day depending on weather conditions I'd say that you make the rule more that no one can be more than 500 or 300 or 200 or whatever you deem decently fair over the average RPM gotten from the day's readings.  For those that are high the easy fix would be to go to a lower nitro fuel.  For those that are more than 500, 300, 200 or whatever low they are allowed to use something higher in nitro.  But for the "tech" run they are all run from a common tank on a stand that sits alongside the model so there's no doping down by adding oil or whatever to the internal tank.

By requiring "equalization fuels" you even the power race and there's nothing to be gained in hot rodding the engine since it'll be dummed down with lower nitro to end up within the RPM and therefore power range.

Similarly props must not be modified other than to remove flashing and very sharp trailing edges if desired for hand starting safety.  They should not be clipped or otherwise shortened, thinned or narrowed at all.

By having this run test and fuel equalization rule it avoids the need to accuse anyone of hopping up their engine.  And it ensures that anyone with an occasional "dog" will be able to compete without fear by using a higher nitro to reach parity for power.

If the fast guys complain and it was originally written into the intent of the event that it was to promote even racing then they can either suck it up and play on even ground or pack up their marbles and go home in a huff.... at least that's how I see it.

I remember back when I flew 80mph speed limited control line combat.  It was a superb event since it let all manner of engines and models compete on an equal footing.  At the start the models got airborn and had to fly two timed laps which had to be more than X amount to ensure they were not faster than the limit.  Once both models were cleared for speed the horn would blow provided they were more or less on opposite sides of the circle.  Otherwise the sideline guys would yell and wave to split apart.  But the pilots were pretty good at flipping around before the timing started to ensure that the models were well apart for the two laps.  As an event the speed limit thing was hugely successful.  It really made the flying interesting.    So I can see where it would be sweet to ensure the engines in these racers were turning at roughly the same power levels before the flag dropped.