Aviation of WWII
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Pilot`s Notes Airacobra Pilot`s Notes

Pilot`s flight operating instructions for ARMY MODEL P-39Q-1 AIRPLANE


Trim airplane nose heavy and turn ignition and battery switches off. Pull emergency release handle and push out on door. (Right-hand door recommended as it provides no obstruction.)


Door will release when handle is approximately 90 degrees to side of airplane. Slightly bank airplane to the right and slide off wing.


a. Turn the fuel selector (figure 8) to reserve tank and turn on electric booster fuel pump. Move mixture control to "FULL RICH."

CAUTION Never use left tank for take-off or landing.

b. Next lower the landing gear at a speed not over 200 mph. A warning light, located on the tubular support at the left-hand side of the main instrument panel (figure 5) glows when the throttle is cut to one-third and the landing gear is not in the locked down position.

c. Lower the flaps if desired, or if necessary because of a short field (full flap may be used when landing). Position of the flaps is shown by a direct indicator on the left wing, over the flap area and near its outboard edge. This indicator is a semicircular piece of plastic that projects from a slot in the trailing edge of the wing. When the flap is fully up, the indicator is not visible. When the flap is one-third down, the yellow portion of the indicator projects above the wing surface. At full down position, the indicator shows one-third yellow and two-thirds red.

d. Return "landing gear switch" to "OFF."

e. Return "flap switch" to "OFF."

f. Emergency operation of landing gear.
CAUTION   In the event the landing gear does not extend, crank it down manually by means of the emergency hand crank.

Place landing gear switch in OFF position.

(2) Turn the landing gear clutch handle rearward; slow the airplane down to 130 mph or slightly less and by means of the ratchet emergency hand crank, operate the landing gear down. If unsuccessful, reverse the ratchet and operate the landing gear up. Then reverse the ratchet again and repeat.

(3) A normal approach is a glide. With flaps full down and power off, the glide path and glide attitude of the airplane are extremely steep, and it is necessary to maintain a gliding speed of about 130 mph IAS in order to have sufficient control to level out before contacting the ground. If a power on approach Is made with the airplane In about the landing attitude, a gliding speed of 110 mph IAS is required.


(1) Forget that the ship has a tricycle-type landing gear and make a normal type landing. This type landing should be one where the nose of the airplane is well up and the main wheels touch the ground before the nose wheel. (In other words a landing attitude equivalent to that with a conventional gear.) This type landing will result in a landing speed between 95 and 100 mph IAS. Once the main wheels touch the ground, the plane will without any help from the pilot, nosedown until the nose wheel is on the ground. There will be no tendency whatsoever for the airplane to ground loop or bounce.

(2) During the landing run, do not lock the brakes or apply them continuously. It Is recommended that they be applied, then released numerous times, thus preventing severe wear on the tires and overheating of the brakes. Stopping will be accomplished equally as well if done In this manner, as it would by applying and holding on full brake.


This point Is stressed as application and holding on full brake will lock the wheels and cause skidding,which will in all probability, ruin the tires on the main wheels.

(3) It should also be emphasized that due to the favorable landing characteristics of this airplane, It Is not necessary to land at speeds above 95 to 100 mph IAS. In fact, the landing run increases greatly In relation to the landing speed, that Is, a pilot landing at 140 mph IAS requires two times the landing run necessary for a landing accomplished at 95 mph IAS.

(4) In approach for landing in cold weather, it Is advisable not to idle engines at low speed. They should be run up and checked frequently for ability to accelerate.

(5) While taxying back to the hangar, the flaps should be retracted, the oil and coolant shutters should be "OPEN."


a. Place the propeller governor "INCREASE RPM" position.

b. Set the mixture control lever to the "IDLE CUT-OFF" position, and at the same time move the throttle to the "FULL OPEN" position.

c. When the engine ceases firing, turn the Ignition switch to the "OFF" position.


a. Place all cockpit light switches, pltot heater switch, fuselage light switches, etc., in "OFF" position. (See figure 5.)

b. Place battery switch in "OFF" position. (See figure 5.)

c. Cage flight indicator.

d. Unlock auxiliary door latches prior to opening cabin doors.

e. If oxygen has been used during flight, close valves to prevent leakage.


Oil dilution is recommended when outside temperature is below 32°F (0°C). The dilution of the oil Is accomplished prior to stopping the engine by operating the oil dilution valve switch (figure 6) to "ON" for approximately 4 minutes with the engine running at approximately 800 rpm. The 4-mlmite operation of the oil dilution valve switch is recommended as this period has given most satisfactory dilution when oil and coolant temperatures have not been too high at the time of dilution. When coolant temperatures are too high (over 100°C (212°F) for coolant and 40°C (104°F) (or oil), it will be necessary to shut the engine off and allow to cool; then again start the engine and proceed as described above.


One quart of gasoline enters the oil system per each minute of operation of the switch at approximately 800 rpm. This will vary at different rpm, but there is very little danger of overdilution.


a. The following acrobatics are prohibited

(1) Outside loops and spins.

(2) Never try any acrobatics with a tail-heavy airplane.


a. The following acrobatics are not recommended:

(1) Snap rolls.

(2) Spinning.


Procedure in case of firedepends principally on the pilot's judgment, type and extent of the fire, and altitude. Fires outside the cabin enclosure sometimes may be blown out at reasonable altitudes by putting theairplane into a dive. If the fire has gained such great headway that it is impossible to extinguish the flames, bail out.

If too near the ground to bail out, land the airplane at once.


In case fumes begin entering the cockpit the cockpit heater should immediately be switched to cold air. This is to prevent prestone fumes entering cockpit through hot air duct in case of burst radiator or prestone line.