Piper PA-35 Pocono

[Stargazer]

One of Piper's least-known post-war efforts is also considered by many as the company's best aircraft never built: the Piper PA-35 Pocono. There are several sources on the web, but the best by far is the New Zealand site AvPlan, from which most of the following images were taken:

http://www.avplan.co.nz/Library/

 

[Stargazer]

As for the fate of the sole Pocono prototype (N3535C), it is very interesting; after being sold to Polish company PZL for local development, it ended up rotting in the open. It was spotted as late as 2004, but its current fate seems to be unknown, although some reports say the fuselage went to a technical school after that date. Here is a picture of the PA-35 taken in the village of Widelka in October 1995 by Hans "Antheii" of the Aviation Forum:

 

[Mark Nankivil]

Very interest Stargazer - thanks!

Reminds me of a mini-Jetstream...

Enjoy the Day! Mark

 

[cluttonfred]

The PA-35 was Fred Weick's (Ercoupe, Pawnee, Cherokee, etc.) last project at Piper before retiring in 1969. Weick discusses the Pocono in his fascinating autobiography FROM THE GROUND UP (pp. 355-362).

Weick quotes a memo from Pug Piper which describes the Pocono as a logical follow-on to the PA-32 Cherokee 6. Pug Piper wrote, "we have a breakthrough in a low-cost high-utility six-place airplane in the PA-32 This same concept could be extended again to a model twice or even four times the size of the PA-32."

A few other points:

• The original concept left open the option of fixed landing gear.
• The aircraft was unpressurized, but the circular fuselage cross-section was chosen to make pressurization easier if it were required later.
• Weick, one of the pioneers and arguably the inventor of the modern tricycle gear, was excited to use a double nose wheel because of its anti-shimmy properties.
• The prototype had two 400 hp Lycoming IO-720s but Lycoming was working to raise that to 520 hp and ready to guarantee 470 hp.
• Other than tweaking handling and control forces, testing showed that the real issue was lack of power and all 520 hp per engine would be needed.
• The PT-6 turbine option was on the table but too pricey, R-1340 radials and a four-engine arrangement were also studied but not adopted.
• In the end, Lycoming came back to say they could only hit 470 hp with the TIO-720 and that only with a lot of time and effort.
• When Weick retired in late 1969, various PT-6 options were on the table but never materialized.

Essentially, creep from a gross weight of 8,700 lbs to 9,750 lbs left the Pocono as airframe without a suitable engine while Beech had already come to market with the PT-6-powered Beech 99.

Cheers,

Matthew

 

[Machdiamond]

fascinating autobiography

Geez, now my bank account just got lighter by $145 tonight without me having any control over it.

--Luc

 

[cluttonfred]

Ouch, I hope those are Canadian dollars.

 

[Caravellarella]

Re: Piper PA-35 Pocono commuter liner prototype......

Dear Boys and Girls, here is a picture with a caption in French of the Piper PA-35 Pocono commuter liner prototype; it never entered production......

The picture comes from the 15th August 1968 issue of Aviation Magazine International......

Terry (Caravellarella)

 

[Grey Havoc]

Another great design let down by the engines/ engine company.

 

[alertken]

GH: one man's "under-powered" is another man's "overweight". An airframer choosing to design into a power void must be ready to fund an engine into that void. Why should the engine man invest into a speculative airframe scheme?

 

[Grey Havoc]

GH: one man's "under-powered" is another man's "overweight". An airframer choosing to design into a power void must be ready to fund an engine into that void. Why should the engine man invest into a speculative airframe scheme?

The reason why the weight was allowed to creep up in the first place was because Lycoming had promised their engine would be reach 470 hp without any problems and they were working on upgrading it to 520 hp. Unfortunately it turned out that Lycoming were optimistic, at best.

 

[hesham]

From the book; Piper Aircraft, and Their Forerunner,

here is a four engined project version of Piper PA-35 Pocono.

 

[Machdiamond]

Fred Weick's "From the ground up" has a good quality threeview of the PA-35, here it is:

 

[Stargazer]

Neat plan, thanks! Really looked like an eggplane Cheyenne of sorts...

 

[riggerrob]

For comparison, competing DHC-6 Twin Otters and Beech 99s normally only had 19 seats installed. More than that would have required a stewardess to meet emergency evacuation regulations.
Pratt & Whitney's PT6A-20 engine debuted with only 550 horsepower. Despite their huge wings, early DHC-6-100 Twin Otters were still under-powered and needed a waiver to certification standards about one-engine climb rates. Later -200 and -300 Twin Otters have more powerful -21, -27 or -35 (680 to 750 hp.) engines to improve single-engine rate of climb.