p51 starters

I think what you're hearing is a backfire as the ignition is kicked in.

The starter rotates the engine through a couple rotations before the ignition switch is thrown - which builds up a bit of unignited fuel/air mixture in the exhaust pipes.

Throw the switch and the exhaust from the now-firing cylinders ignites the accumulated mixture in the exhaust pipes. Bang!

SFAIK, P-51s didn't have explosive cartridge starters. Just ordinary electrical ones with a hand-cranked inertial starter as a backup.

Cheers,

From: Section VII -- Operating Instructions for the P-51

1. STARTING AND WARM-UP

a. Ignition switch OFF. b. Have prop pulled through if it has been idle more than 2 hours. c. Generator and battery switch ON, unless battery cart is being used, then battery switch OFF. d. Throttle 1 inch open. e. Mixture control in IDLE CUT-OFF. f. Propeller control in INCREASED RPM. g. Supercharger switch in AUTOMATIC. h. Carburetor air control in RAM AIR. i. Turn ignition switch to BOTH. j. Fuel shut-off valve ON and fuel selector valve to Fuselage tank (if full), or Left Main tank if Fuselage tank not serviced. k. Fuel booster pump on NORMAL and check for 8-12 pounds of fuel pressure. l. Prime engine 3 to 4 shots when cold. 1 to 2 when warm. m. See that prop is clear. n. Lift guard on starter switch on pilot's switch panel and press switch to START. Caution in use of starter not to overheat. o. As engine starts, move mixture control to AUTO RICH. If engine does not fire, after several turns, continue priming.

WARNING: When engine is not firing, mixture control should be in IDLE CUT-OFF. p. Warm engine at approximately 1300 RPM. Check for constant oil pressure. If no oil pressure or low pressure after 30 seconds, shut off engine. q. Check all instruments for proper readings. r. Check hydraulic system operation by lowering and raising flaps. Loading 800-850 pounds and unloading at 1050-1100 pounds. s. Check communication equipment for proper operation. t. Uncage all gyro instruments. u. Check both LEFT and RIGHT MAIN and FUSELAGE fuel systems by rotating fuel selector valve with booster pump switch in EMERGENCY. Check for 14-19 lbs/sq. in. If drop tanks are installed, check fuel flow by rotating fuel selector control.

Full text here:

ok, that makes sense. i couldn't see any reason to bollox up that motor with a bang starter. but riching up the cyls makes sense. did all the merlins do that? don't remember back farts on lancs...

i'll tack that on the triumph for a joke. thanks, ruf.

Typically, they shouldn't. Maybe this one's got an ignition or fuel or air problem.

e wrote: