Hi Alex;
I believe Brett is correct on the model Windy used in a semi scale Typhoon or Tempest, but I think it might have been a OS, but no matter. A local guy here in the St. Louis area, Walt Brownell, built the same model from Windy's drawings and used a OS.90, but with no working throttle. He used a lockable bell crank adjuster to be able to set a specific ground setting on the carb, and fine tuned with the needle valve. Like Brett said, there was no way he needed the full power, and this let him adjust for the prop he was using at the time. I think the .91 is the largest displacement you can legally use in a stunt model for competition now. I think also that it is common practice for those that do use 4-strokes with R/C carbs, to close down the throttle just a bit to help with full draw. Using a four stroke is all about full draw and making sure you have the best fuel flow you can get. I fly a Top Flite Score with a Saito .56 in it and it is an interesting power plant. Four strokes run completely different from anything else I've used, and I generally follow the Bob Reeves set up on my model. It was what got me the most consistent runs. Search here in the four stroke forum and you will find volumes on it and other people experiences, and I think he has some information posted on the Tulsa Gluedobber's web site. I first flew a four stroke model at the SIG contest years ago. Kieth Sandberg had a kit built Legacy with an R/C version of the Saito .56 in it and made me take a flight with it after the contest. He had his throttle locked down at about 3/4 open. I can't remember anything else about the set up but the model flew VERY nicely and it was what pushed me over the edge to try a four banger. I haven't sold all my other two stroke engines just yet but I do like flying my Score. The four stroke is just another viable power plant choice we have in this event for those that like that type of power plant.
Are you still working in the St. Louis area? I haven't run into you at Buder Park since that day we met, but spring is coming! We have our winter contest, The Ice-O-Lated Stunt Contest on the last Sunday in February. If you are still in town, put it on your calendar and come out even just to watch.
Type at you later,
Dan McEntee