Span 122 cm ( 48 inch ). Wing area 40 dm sq ( 620 sq inch ). Weight original 1500 gram ( 53 oz ). 45 to 50 engines.
Probably there’s no modeller who doesn’t like biplane. Having built several biplanes before I finally intended to produce a really good one. Since there’s hardly a full size craft which can be converted into a competent stunt model, it had to be a purely functional design. DUETTO was designed as a high performance aerobatic airplane with all out competition in mind. At least I wanted to find out how good a biplane can be designed and how well it can fly ( my ideas about design can be found on another page ). The outcome was : a bipe CAN fly - and very good, at that!
Duetto was built for a Super Tiger 46 ( going below this capacity in a biplane doesn’t seem sensible to me ). This engine weighs about 300 gram with muffler. One of those modern 50 engines should be a better choice, but engine weight should be considered.
Except for some minor differences in the centre both wings are built exactly the same. Flaps are on both wings; the top flaps are connected to the bottom flaps via pushrods. A small hatch at the fuselage rear end gives access to the elevator horn to allow adjustment of elevator travel and trim.
Duetto flew better than expected; it even won a few contests. Probably a world top class flyer would not win the world championships with it. But it can hold its own quite well among average monoplane stunt ships.
Duetto had one irksome habit : in very hot weather it refused to do a nice last corner in the hourglass ( no problem in cool air ). Obviously there was some lack of lift. If I had to do it again I would increase airfoil thickness and flap chord. A slightly enlarged version was successfully flown with a ST 60.

TWINI by Lutz Hetges, Germany. has built a slightly enlarged Duetto version for Super Tiger 60. Also Thierry Saunier, France, has built this version. He has a plan available.