Unusual agplanes: Bug bombers

Flight Journal, Jun 1998 by Lert, Peter

And now for Something Completely Different

Given a sufficiently specialized application, you're likely to find a particularly weird aircraft to fulfill it Take Poland in the 1970s, for example: a burgeoning and hungry population, big open fields that needed to be sprayed, a dearth of avgas (but plenty of turbine fuel) and a history of aeronautical innovation. Result the Belphegor (named after an ancient fertility god), a big biplane powered by-get this!-a fanjet engine that used jet exhaust to help disperse the product being delivered. Given the notorious inefficiency of even fanjets at low speed and altitude, perhaps it's no wonder that we haven't seen the Warsaw Pact's skies darkened with fleets of Belphegors.

On the other hand, the skies of Australia and New Zealand were, if not darkened, at least a bit grayed by a few dozen of one of the most remarkable (and possibly the weirdest looking) airplanes ever builtthe immortal Transavia AirTruk. Due to Australia and New Zealand's rough farm terrain and poor soil, an airplane was needed that could not only haul hefty loads and maneuver in really small fields, but would also be able to land in or right alongside them; the huge dispersal rates for phosphates would require such frequent reloading that flying back even to a fairly nearby airport would be economically unfeasible.

An enterprising Italian designer working in Australia came up with the answers. For good low-speed performance with minimal induced drag, a long, narrow wing was required; for short takeoff and landing, great big flaps; for maneuverability, great big control surfaces; for the structural advantages of a truss-braced biplane, but with less drag, a lower wing that's much shorter than the main one; for safe operation from short, rough fields, a hefty trailing-link tricycle gear; with widetrack mains on the lower wing.

But wait; there's more! Rather than putting the pilot aft of the hopper, this design puts him on top of it (for safety and superb visibility), with the loading chute right behind the cockpit With tri-gear, there's no need for an aft fuselage to accommodate a tailwheel. Instead, there are two separate T-tails on booms running aft from the wing this allows a loader truck to pull up between them while the airplane's engine can be left running. The final touch addresses personnel needs: since the typical top-dressing operator might leave his fueling and loading trucks in the field for days, a tiny aft cabin was added to allow the fueler/loader/flagman to be transported to the work site in the airplane each day.

The result of these requirements looks decidedly odd-a twin-tail, tri-gear sesquiplane with a fuselage shape reminiscent of an angelfish. But I can attest from personal experience that it flies absolutely magnificently; in fact, if I could find one of the handful that made it to the USA, it would make a wonderful airshow airplane. Overall, the design worked so well that some 200 were built and sold all over the world. The basic aerial-application version was soon joined by variants for cargo, air ambulance, aerial survey and even armed counterinsurgency flying.