Piper Navajo Chieftain (oz1326)

About this Plan

Piper Navajo Chieftain. Rubber scale twin.

Quote: "The Piper PA-31-350 Chieftain is a direct descendent of Piper's first Navajo twins, and differs mainly in its extended fuselage, and greater horsepower. Approximately two feet were added to the overall length, and the horse-power increased from 310 hp in the basic Navajo models to 350 hp in the Chieftain along with counter rotating engines. Three-blade, constant speed props could then rotate in opposite directions, eliminating torque.

The Chieftain cruises at 260 mph at 24000 ft, making it quite popular with the business world. An added feature is the baggage compartment at the rear of the nacelles, capable of carrying 150 pounds in each. The standard Chieftain has four passenger seats, with two more optional. Four individual seats facing one another across foldaway tables, make up the executive version. Toilet and refreshment units could be replaced by additional seats.

If ever you have longed to put full figure pilots in a rubber powered model, now might be the time to do it, as a twin lends itself nicely to the task by eliminating the need for motor clearance. For added detail, a full cabin interior is also feasible. Seats made of Air Mail type bond paper would add little more than a gram or two.

At first glance, it might seem that the Chieftain would be a poor choice for a rubber powered model, considering the close proximity of the nacelles to the fuselage, thus limiting the size of the props. However, for a 27-inch span model, two three-blade, 6-inch props move a lot of air around.

The model itself is very close to scale out-line, having been photographically copied, projected, and traced, from a 3-view which appeared in Air Enthusiast 1973. Proportional dividers were used to double check dimensions, so despite the model's squarish looks, it does retain the profile of the prototype.

One difference in the basic construction technique of this model bears some explanation, and that is the manner in which the fuselage and nacelles are attached to the wing. This, of course, is not imperative, and it would be a simple matter to alter the construction to suit ones own personal preference.

To explain: the fuselage frame will be notched as shown for the main spar, leading edge, and trailing edge of the wing, and fits between the root ribs. This necessitates leaving the fuselage and wing bottoms uncovered until final assembly. The same applies to the nacelles. This procedure not only simplifies mating the wing to the fuselage and nacelles, but also provides a stronger joint and more accurate alignment if care is taken.

In choosing the wood for the fuselage, try to find some medium hard sticks for the longerons. I prefer to cut my own from a suitable sheet, and in that way it's possible to get sticks more nearly alike. The rest of the fuselage can be made of lighter stock..."

Update 19/03/2018: added article, thanks to RFJ.

Update 04/01/2019: Replaced this plan with a clearer copy, thanks to theshadow.

Supplementary file notes

Article.
Previous scan version.

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction