Plan file details
Piper PA-36 Pawnee Brave 300. Radio contol scale model, for 40 power. Scale is 1/8. Uses foam core wings.
Quote: "Sport performance highlights this fine Stand-off scale cropduster. For .40s. Piper Pawnee Brave, by Art Heenan.
I am a sheep and beef cattle farmer, in far off New Zealand. Agricultural aircraft at work, spreading their loads of superphosphate fertilizer over the hills, have always been a familiar sight to me. The sight and sound of them at work, with their low level sowing runs and wing-over like turns, has always fascinated me. One of my earliest memories is of watching a pair of Tiger Moths spreading fertilizer from a strip near our house, and it was this that kindled my interest in aircraft, and started me building models. I have been building R/C scale models for the last seven years, almost all of them my own design. Agricultural aircraft are my favourites.
I designed this model for general sport flying to stand-off scale standards, although it is completely accurate to the factory three view I worked from. A few calculations showed that a model built to 1/8 scale would suit a .40 - my favourite size engine. This resulted in a reasonably compact sized model, with a wing span of 58-1/2 in and wing area of 525 square inches. The simple modern line of the Brave lends itself well to modeling, construction being reasonably simple with foam wing cores and all sheet tail surfaces. The fuselage, too, is reasonably simple, although more work.
I firmly believe that lighter models fly better, and although my Brave ended up a little heavier than I would have liked, its flying characteristics are excellent. With a little care in wood selection, I think the model can be built somewhat lighter. I duplicated the full size aircraft in using engine downthrust and positive incidence in the wing. This allows the model to fly in a realistic manner and speed. The basic design of the Brave model has been kept as simple as possible, while maintaining good scale appearance. The addition of the scale detailing, and a good paint job results in a very attractive model.
The aircraft. The Piper PA25 Pawnee first flew in 1959, and revolutionized agricultural aviation, the cockpit area being specially designed for pilot safety in the event of a crash. The pilot sat high up, giving good visibility from behind the loaded hopper. This aircraft remains in production as the Pawnee D, with a 260hp engine.
The PA36 Pawnee Brave was introduced in 1971, and was a completely new aircraft although retaining the same basic layout. Of all metal construction, it proved a success but was rather underpowered by its 285 hp. Continental 'Tiara' engine which had the propeller geared at a 2 to 1 reduction ratio. Performance was greatly improved with the installation of conventional 300 or 375 hp Lycoming engines on the Brave 300 and Brave 375. Wing span of the Brave is 38.77 ft, with a length of 26.79 ft.
Construction. No problems should be encountered when building the model, but follow the sequence set out in the following detailed instructions. As with all models, and especially scale models, weight is of prime importance, so pick your wood carefully. I would recommend making a kit of all the components before starting construction, as this allows building to progress with no holdups. Almost all the construction was done using aliphatic resin glue.
Wings. Cut the foam cores for the two main panels and the centre-section using the template on the plans. Epoxy the 1/8 in balsa false LE and TE to the cores, and shape to match. Inset the ply wing bolt plate into the lower surface of the centre-section, and glue the balsa blocks into the two of the wings, where the torque rods will be anchored in the ailerons..."
Direct submission to Outerzone.