AvPlan Library

Our library has a range of digital commercial, contract, technical and industry material held in support of customer work. Documents cover commercial and some military aviation tenders and developments from 1980 to the present day including a range of generic MRO and other contract documents.

A collection of archived hardcopy reference material is also held in support of some customer work. Most of it is from the 1950’s through to the 1980’s. These documents cover aviation technical and commercial developments; for example aircraft specification and performance documents for more than thirty aircraft.

There are even some for project aircraft that were never built as advertised, e.g. the McDonnell Douglas MD95, the BACX-11, the Lockheed C-130 Twin and others.

Some earlier published educational, industry and magazine material dates from 1922 to 1950. The earliest is the lecture notes of my father who joined the Royal Air Force as an officer cadet and entered RAF Halton, Buckinghamshire, UK in 1922 at the age of 15 years. He was taught aeronautical engineering as it was then by none other than A.C. Kermode who wrote a definitive text book of that time, “The Theory of Flight”. The hand-written text notes have, amongst other features, a description of how to rig the flying wires of a biplane of that era.

We believe a library of this type assists understanding of how the air transport market and the aircraft that serve it have developed over past decades and why some products were successful, while others attracted no orders. It forms a valuable basis for the copy-writing of articles on aviation industry subjects.


AvPlan AeroArchive 1: The Piper PA-35 Pocono

Piper Aircraft Corporation archive material – 1968.

The Piper PA-35 Pocono – 18 Seat Commuter Airliner - a programme cancelled.

The AvPlan Library holds some of the bi-monthly “Piper Pilot” published by the Piper Aircraft Corporation during the 1950’s and 60’s when a few new designs were produced as prototypes, but only some of them entered production. One that was developed from 1965 to 1968 and flight-tested was their Piper PA-35 Pocono.

It was their largest aircraft designed initially as an 18 seater under FAR Part 23 regulations and powered by two Lycoming TIO-720 engines of 520 HP which still left it somewhat underpowered for what it was.

Piper consulted with commuter airlines extensively before and during production of the prototype. Airwork New Zealand Ltd held the Piper agency for New Zealand at that time, and the Managing Director in 1968 was John Brazier who was an occasional visitor to both the Lock Haven and Vero Beach facilities of Piper. John did mention to me after one of his visits that he had been told of a reluctance on the part of the founder of Piper (Mr William T. Piper) to fit turbines to his aircraft as they would make the aircraft much more expensive and be contrary to what Piper was known for in the market place (i.e. reliable, economical aircraft with very good payloads and, above all, value for money). Piper wanted to achieve a target price of USD200,000 for the aircraft in 1968 and could obviously not do that with turboprops fitted.

The maiden flight of prototype N3535C took place on 13 May 1968 at Vero Beach in Florida, USA.

However, the PA-35 did need the move to higher power offered by the PT6A or TPE331 turboprop engines and was never going to be successful without it. The aircraft was also stretched in length by insertion of a 2.5 foot (762 mm) plug just aft of the wing trailing edge which would have allowed up to 23 passenger seats under FAR25 transport category certification, but the limited power of the TIO-720’s was even more noticeable then.

Unfortunately 1969 was not only a difficult time to sell new aircraft to commuter airlines, but also the time of a hostile raid for ownership of Piper through share purchases on the share market by Bangor Punta Corporation, a sporting equipment manufacturer, which was eventually successful and ultimately resulted in the departure of all the Piper family from the company. With all these factors conspiring against it, the project was cancelled when the new owners of Piper decided against investing in a new commuter airliner at a time when commuter airlines were mostly making financial losses.

The Bangor Punta Corporation was eventually bought out by Lear Siegler, by the way.

As a three-abreast 18 seat commuter airliner designed specifically for the commuter market with large doors, spacious flight deck and flexible cabin design, and typically good payload it might have been a successful aircraft competing against some other two-abreast 18 seaters that are still in service forty years later. It was a pity it was not offered to compete when the market recovered later.

There was only one prototype built N3535C which remained at the Vero Beach factory for some years until Piper eventually sold it to Pezetel in Poland who were a subcontract assembly company for Piper in Europe. Whether it was sold or gifted to Poland and whether or not it was for training or for further development is not known by this writer, but nothing more was heard of it. A picture of N3535C taken in Poland in October 1995 is below.

Considering that Viking Aircraft in Canada are now building new DHC6 Twin Otters again to order, which is a design from the 1960’s, perhaps a new market analysis might just show that the PA-35 design with modifications could still sell as a Part 23 or even Part 25 commuter/utility aircraft today, subject to the substantial investment cost of such a development and certification programme of course.

Since I have never seen the following pictures which I have scanned available anywhere on the internet, they are reproduced here for those interested, with permission kindly granted by Piper Aircraft, Inc.

Piper PA-35 18-Passenger Commuter Liner

Piper PA-35 18-Passenger Commuter Liner

Piper PA-35 18-Passenger Commuter Liner

Piper PA-35 18-Passenger Commuter Liner

Pocono makes its debut in Paris

The following picture of the sole prototype N3535C was taken in the village of Widelka, Poland in October 1995 (photo by Hans Hoogers – ‘Scramble’ reprinted with permission). The fate of the aircraft since then is not known.

Pocono in Widelka