Engines

Engines & Models

Choosing an Engine

From 1996 the old restrictions on engine capacity of 10cc max for two strokes and 20cc max for four strokes have been lifted. This does not mean that the old style models will not be suited. Indeed for a newcomer it is the ideal place to start. There will be plenty of good used airframes and engines for sale as seasoned competitors upgrade their equipment - check the private ads in the mags and the model shops.

If you've yet to invest in a motor, bear in mind that although there is no upper capacity limit, be sensible! Purchase a motor you have seen being used, preferably in the comps. Whilst some top aerobatic fliers in this country are using four strokes,

YS 140LM OS 140RX

in particular YS 140LM (above), these engines require high nitro fuel and can be expensive to maintain. I think even four stroke fans would advise purchasing a two stroke initially, for reliability and reduced costs.

The most popular .60 motor is probably the OS Hanno Special and matching pipe, but now retails at over £300, so you may wish to consider the Webra 80 or 60 as slightly cheaper but competitive alternatives. Other suitable motors include OS61 RFP, Webra 120, OS 140RX (all these motors available with fuel pumps). If costs are a major consideration consider the Super Tigre 61, 75, 90 range, in particular the ST 90 which has 2bhp for under a £100 and on low nitro fuel.

You can purchase free standing pumps, a perry pump being a good example, to suit any motor but bear in mind, basic carbs fitted to some cheaper engines may not cope with a pressurised feed. A pumped motor will enable you to install the tank over the models c.g., minimising changes, but pumps are not essential - simplicity and reliability are much more important initially.

Models

Listed below is a selection of the more popular designs, varying from a basic plan to the top of the range models which has a high degree of fabrication and accuracy, but at very high cost. If cost is important, consider the DSM Excelsior 177 or Graphic 60 & ST90 for a total outlay of between £200 and £300. While all models listed are eminently suitable, remember that bigger models will always fly smoother.

To find out whether aerobatics is for you why not build a Dave Smiths Saphir. The smallest of the range for an Irvine Q40. John Morton did (his photograph appears below) and he is extremely pleased with the results. It is the smoothest small aerobatic model I have seen, the secret is to build it very light. (click for more details)

.40 - .60 two strokes

.60 two strokes(piped) .91 four strokes

120 - 140 Four strokes 120 - 140 Two strokes

Chili Wind (RCM&E plan)

EZ Mystic 90 (Irvine)

Aerostar 52 (DSM)

Aerostar 62 (DSM)

Saphir 40 (DSM)