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5 ways to increase model performance

- without buying a new power system!

Article by Andrew Gibbs

There are a number of ways to tweak a model to make sure its performing as well as it possibly can. This short article discusses how to get the most performance from a model, without buying a new power system. The propeller is a great place to start:

1. Choice of Propeller
Experimenting with propellers is often the easiest and most effective way to get a model to perform better. The greater the load a prop places on the battery, the more power your motor will draw. However, even small increases in prop diameter can cause big changes in the current drawn by the motor, so when changing props, always be sure to check the current consumption is still within the limitations of your motor, battery and ESC.

Another easy and simple way to get more performance is to check that the pitch of the prop is appropriate to the needs of the model. You may get more speed from a model by changing to a prop with a greater pitch. For example, instead of a 9 x 5, maybe try a 9 x 6. Again, always check the current consumption when changing props.

If rate of climb and not level flight speed is your preference, changing to a lower pitch prop may work wonders. For example, an electric glider might climb significantly better with a 12 x 7 instead of a 11 x 8.

2. Balance That Prop
An unbalanced propeller can develop a significant amount of vibration, especially at high rpm, and that vibration uses energy from the motor which is then not available to turn the propeller. For this reason, balancing the prop can yield a surprising benefit in performance.

For electric models in particular, I recommend investing in a good quality balancer. The investment will repay dividends for every one of your models in the future. Spinners can also be out of balance, so remember to balance them too.

3. Check control surface alignment
A model can appear to be flying straight when in fact it’s crabbing sideways a little. This presents the side of the fuselage to the airflow, and can really slow the model down. Crabbing can be caused by incorrectly set up control surfaces – if your rudder is deflected right, and the ailerons left (left aileron up) when the sticks are centred, chances are that the model is crabbing. If you get the controls properly centred, the model could pick up a surprising gain in speed.

Some models have two elevator halves, connected by a wire joiner. If the two halves are not aligned correctly, one elevator half may be up, while the other is down. This will produce drag, slowing the model down.

4. Optimising the balance point
A model with an excessively forward centre of gravity (CG) will require an additional amount of up elevator to maintain level flight, compared to the same model where the CG is correctly positioned. While a forward centre of gravity is good for longitudinal stability, the necessary up elevator will cause some additional drag. Also, the up elevator means that the tail will be producing more of a downwards load than necessary, so the wing will have to produce more lift to compensate, with an associated increase in induced drag. Both of these factors will slow the model down somewhat.

It can therefore be worth moving the CG rearwards in small increments, carefully assessing how the model flies after each change. As the CG moves rearwards, the elevator will become more sensitive, and so it may well be sensible to reduce the elevator throw a little. Take great care not to move the CG too far rearwards, or the model will become excessively sensitive. If the GC is taken even further rearward, the model will become unstable and even unflyable.

5. Flying style
Your flying style can significantly influence the performance of a model. Tight turns cause a lot of drag, robbing the model of airspeed. Instead of making tight turns, try easing them out so that turns are wider. These cause much less drag to be generated, and the model will fly for longer and/or faster.

You can find a lot more information about electric power systems in the electric power systems series, available here

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