Plan file details
Sorrel Aviation Hiperbipe - Scale model for .60 engines and five function radio control.
Quote: - "BACK in February 1976 when my copy of Aeroplane monthly arrived, I (and a few others) was fired with enthusiasm for the home-built bipe that was pictured on the cover, so I did a few sums! My aim was to build something for competition and fun flying and, with that, test the feasibility of building it again for Class-1 judging.
The size was to be as big as an average 60 could be expected to pull,-and, to cut a long story short, I decided on 2-1/2in to 1ft (just over 57in wing span). Smaller, I thought, would be short on lift - a theory which, in the light of experience was unfounded - and larger, would have given a really vast fuselage. The next thing to do was to 'dig up' some more gen. After referring to Janes 'All the World's Aircraft', I wrote to Sorrell Aviation in the U.S.A. who sent me a good set of detailed photographs and a plan.
The construction is fairly straightforward and should present no problems to anyone who has built a few models. The only unusual feature is the wing fixing, which is basically the sailplane system of tubes and rods. For retention, you 'leap inside' the fuselage with four bolts, one for each wing. This overcomes the problem of that big window in the cabin roof and maintains a smooth, uninterrupted fuselage underside.
...Once you have the cg and thrust-line right, you will find Hiperbipe's handling very good indeed, and it is responsive at all speeds. With the flaps down, in any sort of wind, you should take care not to hover too long, is it does not look authentic! Take-off is easy, but should not be hurried. Feed on the throttle and hold her straight allowing the tail to rise. When the speed is good (subject to strip type and condition) lift her off with a small dab of elevator. Don't attempt to climb until the model's airspeed increases. The landing approach is also good, with the model seeming to settle into a definite groove and needing only minor assistance with elevator and throttle.
Aerobatics are straightforward, with a 'snappy' roll rate, but loops should be kept rather small or the top will get a bit floppy. This will depend, to a certain extent, on the motor and the weight of your model. Incidentally, the scale loops I have seen are usually quite small. I would rate the Hiperbipe as a very versatile model, from Sunday-flier to competition entrant, and I wish all its builders 'Happy Landings'!"
Direct submission to Outerzone.
Update 12/04/2017: added article, thanks to RFJ.