De Havilland Puss Moth (oz11001)

About this Plan

De Havilland Puss Moth. Radio control scale model for electric power with geared 400 motor.

Quote: "Chester Lanzo's semi scale Puss Moth (oz7817) needs no introduction as one of the best free flight models of the era. Designed and first flown in 1939 it won many rubber powered free flight scale competitions. Some years ago I came upon a building feature and plan by Hal Cover but this time it was Jumbo Scale (still rubber) the Puss Moth (oz440) in an issue of the American magazine Model Builder in about 1972. As I was then well into RC power, gliders and soaring, the Moth was a 'one day I will build that' project, so I kept the magazine.

De Havilland Puss Moth, by Tom Charlsworth.

Last year when I was reading through the latest SAM magazine, that had just arrived in the mail, I read about the new class called 'Spirit of SAM Electric' together with the proposed rules for 400 powered electric versions of those famous rubber models of yesteryear. By now I was well hooked on electric flight and I remembered Puss Moth. Putting on the 'thinking cap' and burning some midnight oil, I came up with a winner as far as the conversion goes and after a few minor experiments and improvements I am more than happy with the results which I would like to pass on to you, if you are contemplating a similar project.

The model has a sparkling take-off on short grass with a nice climb to thermalling height. It looks and sounds best lower down, 50 to 100 feet, where it can be appreciated by admiring viewers - the 'Speed Gear' even sounds a little like a Gypsy on half throttle too. It needs to be built light to fly well so 22 oz with a 7 cell 500 AR will give approx 7 minutes running time in still air, or with 700AR cells air time is 10 minutes plus.

The model. Starting at the nose, the detail changes regarding the conversion from rubber power to electric is as follows: 11 x 8 CAM Gear Prop, Speed Gear 4:1 400 6V motor. Laminated nose block hollowed out to clear the motor gearbox and faced with 0.8mm ply drilled for shaft and mounting holes. Access is through a hatch constructed in the top of the cowl which is held in place with clear tape. No downthrust or sidethrust seems to be required.

Fuselage construction: The fuselage is straightforward building. I stripped a light firm sheet of 3mm balsa for all the longerons and uprights. I fitted extra gussets in high stress areas, some faced with 0.4mm ply (wing hooks etc.).

The switches speed controller, Rx and servos - the smaller and lighter the better - fit onto small pads of 1.5mm balsa faced one side - the servo side - with 0.4mm ply and glued to the uprights, in the cabin area. Seal the ply faces with dope etc, and use servo mounting tape to hold the components in place. I use very light balsa push-rods. The UC wire is 14g (about 2mm diameter) and is attached to 3/4 in (19mm) wide ply faced cross pieces with small saddles and self tapping screws. I used Williams wheels to start with but have changed to the new 'H' series' Trexler wheels which are lighter and have more give.

There is an 8 in (203mm) full width hatch along the bottom starting at the wing leading edge upright, for the battery. This is a 3mm square frame, the same as the fuselage. It is curved to follow the lines of the fuselage and is faced on the inside with 0.4rnm ply. A simple ply tongue & slot is fitted in the front end and a swivel latch..."

Quote: "Hello again, long time since last sending. I have found out that you have only the plan for Lanzo Puss Moth with rubber engine. Now you can get the same airplane, but with an electro engine. The copies of plan and article have been printed earlier in Electric Flight Internasjonal no. September/October 1997. DH Puss Moth, by Tom Charlsworth from Electric Flight International September/October... Best regards, Kjell"

Direct submission to Outerzone.

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