The one and only Piper PA-35 Pocono - circa 1968
The voiceover in the PiperJet Altaire video I posted the other day said that the Altaire has “the largest cabin ever in any Piper aircraft”. Well, that might not be completely accurate… meet the Piper PA-35 Pocono.
Piper Aircraft was on the warpath in the 1960’s… after introducing the PA-23 Apache in 1954, which happened to be their first American Indian named airplane as well as their first twin, Piper was really pushing an enlarged line of twin engine aircraft. The 4-place Apache grew into the 5-place Aztec by the late 50’s, and when the 60’s began, the Aztec had been made into a 6 seat aircraft with 250hp hanging off each wing. Soon after, in 1963, the PA-30 Twin Comanche first flew, then there was the PA-31 Navajo first flight in 1964, and the PA-34 Seneca first flew in 1967. That’s a lot of development of production-bound aircraft in a relatively short period of time.
But their biggest twin-engine effort was an airplane you most likely have never heard of… the Piper PA-35 Pocono. While the other aircraft that had exited the Piper design laboratory were relatively logical extensions of other Piper projects, the Pocono was a wild departure. The intent was to provide a small airliner that would appeal to the growing number of feeder airlines. The basic concept for accomplishing this was a really wide fuselage cross section. The Pocono fuselage was seven feet wide! Umm, did you hear me? Seven feet wide! This allowed the approximately 40 foot long fuselage to be set up to carry a total of 18 souls, with the passenger cabin having three seats across, in a 1-2 configuration with an off-center isle between.
When you consider the advantage of easier CG handling by reducing the number of passengers seated well forward or well aft of the center of gravity, along with the really large loading door, the separate split airstair door up front for the cockpit crew, and the overall generally good looks, the Pocono seemed to be on a really great journey.
Where Piper seemed to miss the mark was in the powerplants. Originally built with Lycoming TIO-720 eight cylinder engines making 475 hp, the Pocono seemed almost surely destined to be under powered. A Beech 18 (Twin Beech) with two 450 hp radial engines was only good for a max of 11 bodies, so the idea that the Pocono was gonna be viable with 18 bodies seemed unlikely. It does look like the PA-35 came in with an empty weight about 1,000 pounds lighter than a Twin Beech, but more horsepower was desperately needed. Lycoming had been working to increase power output to 520 hp, and it appears Piper was really counting on that as a way to make the Pocono perform acceptably, but the engines never came to be. Plus, it would seem that there was really more of a need for something in the 700 hp range for an aircraft meant to carry so many people.
Turboprop engines were becoming a real option for aircraft designers at this time with the Pratt & Whitney PT6 having entered service in 1964. Beech introduced the Beech 99, a 15 passenger commuter type aircraft powered by 550 hp PT6’s in 1968. Later on, Beech upgraded the engines to 680 hp and then 715 hp to get better performance. Had the Pocono been designed around the PT6 from the start, things might have gone very differently. The wide fuselage cross section might have seemed more comfortable than the B99’s 2 across fuselage. Maybe Piper was really working hard to keep the cost down for their potential customers, the smallest of feeder airlines, and saw piston engines as a way to achieve that. As it turned out, those smaller airlines were having trouble making money and staying in business in the late 60’s, and when Piper couldn’t get the piston horsepower that was needed, the project was stopped.
Lonely Pocono prototype in 1995 in Widelka, Poland (photo: wikipedia)
By 1970 Piper hinted at either a four engine version, or a turboprop version, but neither idea was advanced. In the late 70’s Piper sent the PA-35 Pocono to Poland as part of a program presumably intended to develop the airplane over there. However, nothing ever came of it. As seen in the last picture here, the prototype Pocono was spotted in the mid 90’s looking very lonely in the town of Widelka in Poland. What an interesting and sad end to a very unique aircraft. I’m not aware of the status of the airframe today, but hopefully it still exists.
So it looks like that Piperjet Altaire video was off a little... I’m pretty sure we’d have to say the Altaire has “the second largest cabin ever in any Piper aircraft” : )