Powerplant

 

 

POWERPLANT

The Aeronca JAP gives the builder and 0wner of G-AYDY a fuel consumption at economical cruising rpm of 2150 (57 Kts IAS) of 2 gallons per hour. The tank on this aircraft holds five gallons, so that a safe endurance of 2+ hours is available, giving a still air range of 117 nautical miles. Builder’s notes (from the PFA) state that the standard tank holds 6 gallons, and that a cruise speed of 70-75 m.p.h. (60-65 Kts.) is obtainable at a fuel consumption of 2 galls/hr. 

These figures seem optimistic for the JAP engined Minor. Power plant controls are the simplest, comprising fuel on/off cock; throttle; and magneto advance and retard. G-ASEA has the advance and retard mechanism linked to the throttle control, so that its handling is of no concern to the pilot in flying the aircraft, whereas G-AYDY has a separate lever in the cockpit, taking the place of the normal mixture control and this requires the pilot’s attention. 

In normal flight, the lever is kept at full advance. There are also differences in priming arrangements, for G-AYDY has a Ki-Gas doping system fitted for external operation by the man swinging the propeller, G-ASEA has a carburettor choke operated also by an external lever. The choke is so arranged that when the throttle is opened beyond the halfway point, the choke is returned to normal running. 

Fuel is gravity fed from the tank under the top of-the fuselage decking immediately aft of the engine bay, and the carburettor is fed permanently in hot air from a jacket surrounding the exhaust pipe. This arrangement shows clearly in the photographs. There is no record of this installation having suffered from carburettor icing.