July 2013
If at first you don’t succeed, don’t “tri” again. But Piper’s trimotor testing wasn’t all for naught.
What do you do when you’ve completed initial testing of a new version of your wildly popular single-engine aircraft? If you’re Piper Aircraft in the 1960s, you slap a couple more engines on it and try it out as a trimotor.
That’s just what happened in 1964. Piper had completed initial tests on its PA-32-260 Cherokee Six and used that airframe to attach two more engines to the wings (in this case using the 115 hp Lycoming O-235) while retaining the 250 hp Lycoming O-540 of the “Six” for the center engine.
The two 115 hp engines did not provide adequate power for the airframe with the center engine shut down. Likewise, the center engine didn’t perform well on its own with those heavy engines on the wings. Adding 150 hp Lycomings all around and changing the cowling on the wing engines also didn’t yield acceptable results and the trimotor concept was dumped.
All this tinkering around was not in vain, however, as Piper decided to dump the center engine and continue development of a twin. The PA-34 Cherokee Twin Six was a fixed gear design first flown with the 150 hp engines used on the trimotor. Piper then tried 180 hp Lycoming O-360 engines coupled with constant speed propellers, a modified wing and the vertical tail from the Cherokee Six. Next up was a prototype with retractable gear and a nose modified to accept the gear.
By the time the PA-34 made it to market in 1971 its wingspan had increased by two feet, the dorsal fin and tail had been replaced by a larger tail and it boasted one fuel-injected 200 hp Lycoming LIO-360-C1E6 and one Lycoming IO-360-C1E6. It was designated PA-34-200 and named Seneca. The base price of $49,900 bought you a nice twin that could cruise at 163 knots at 75 percent power.
In 1972 the Seneca’s gross weight and useful load were increased by 200 pounds. It also received new aerodynamically improved wingtips, a new autopilot and an optional Flight Director system.
The Seneca has the distinction of being the first light twin to receive FAA certification for flight into known icing. The de-icing system was available as an option or as a retrofit kit.
Piper press releases for the 1974 model announced that “the large utility door located aft of the rear passenger door is now standard,” “visibility in the Seneca is also better in 1974 with the addition of a fourth window on either side of the cabin,” and “new options such as an improved ventilation system, the Quietzied soundproofing package, exclusive push button adjustable front seats and refined nosewheel steering allow both pilots and passengers to mix business with pleasure.”
Next month: Seneca II, III and IV.
Jennifer Dellenbusch is president of the Piper Flyer Association. Send questions or comments to editor@www.piperflyer.com.
