Upset II - Radio control aerobatic competition model, for .61 power.
Quote: - "Upset really started back in 1953 with a Sparky (oz2914) designed by Harry Hundleby, which was my first radio model. About five years later Sparky begat Uproar (oz2220) the only thing in common being the shoulder wing. Uproar was a successful contest model as far as I was concerned, although others thought otherwise. Its only real problem was that it was a functional design and as such was rather ugly. As a result of this and the fact that low wing models tended to have some advantages with the then current contest pattern of 1963, Uproar gave way to Uplift (oz6027) which had an Uproar wing and tail in low wing con-figuration on a streamlined fuselage. This again was fairly successful but was still not quite good enough in my opinion for the current pattern (1964), the main problem being a reluctance to spin and the fact that when flown with reeds, it tended to be rather twitchy. It was therefore decided to build a new model for the Swedish World R/C Championships in 1965, so a new model with tapered wings was designed. Due to the silencer rule which came into force in 1965 it was made smaller than Uplift, 600 instead of 750 sq in, so I could continue using a 49 size motor. However, since the model weighed 6-3/4 lb and had a glide like a brick it was decided to make a larger model and use a 61. This resulted in Upset, which is in many ways similar to Uplift, having the same wing area and weight. However, the wing has a lower aspect ratio as I have found that models seem to roll better if the wings have a short span. The wing taper, apart from looking better, helps the model to spin as the tips stall more readily on a tapered wing than on a parallel chord wing. The tail moment was lengthened to try to make the model smooth in pitch although, whether this has worked I am not sure..."
Upset II, RCM&E, April 1968.
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