What's Trimming?
You've finished building your new model, test flown it and it goes great. Got the control movements sorted out and it loops and rolls. Right, on to the next model! Yeah, right!!!
A test flight should be just that - a check that the model goes up and comes down and that it behaves predictably. The first few flights should be used to get your engine and propellor combination sorted out. If you've already flown with the engine in another model, this will be a fairly short process - you know the propellor size and type that it flies best on although this may vary slightly with your new model. If the engine is new, make sure that the engine is well run in and that you're happy with the propellor before you move on to trimming.
Trimming the model has nothing whatsoever to do with the trimming levers or, on more expensive radios, the digital trims! A well designed and built model shouldn't need these moved anyway (and I believe in Santa Clause, too). Trimming the model is a process which is designed to improve the flying characteristics and ease of contol when manoeuvring your model. Although all the diagrams in these pages are very idealistic, it may not always be possible to get an "absolute" solution to any particular characteristic. In these cases, you have to make a judgement call and balance the behaviour in one mode against that in another. All models will benefit from trimming - even a trainer - although pattern and aerobatic models will benefit the most. There are four fundamental stages in properly trimming a model - the engine, the airframe, the controls and mixing. It is essential that the trimming process is carried out in this order because the number of iterations to get a correctly trimmed model will be greatly reduced.
The level of trimming that you can achieve is also limited by your transmitter. This is where computerised radios really come into their own with channel mixing, travel adjust, offsets and so on. Ever wonder what they did? Me, too! The problem with the (thick) manuals that come with computerised gear is that they only explain how to programme the radio. They are extemely poor at telling you why you would want to! Hopefully, these pages will help you to understand why you would want to read the instruction manual!
Where flying tests are required, choose a day with little or no wind and turbulence.
When we come to describing programming computerised radios, I will use the terminology adopted by JR - because that's what I fly with - but if you're a Futaba or Sanwa owner, I'm sure that you're well capable of identifying the appropriate functions.
If you think I'm real smart for knowing all this stuff, I'm not. The majority of this series of web pages is based on the expert knowledge and skills shared with me by Ian Beveridge and Doug Thornton over several beers! Thanks for sharing your knowledge.
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