MIflyer
1st Lieutenant
No doubt that everyone here has read many times of instances when Merlin engined aircraft were hit in the radiator that the pilot had a very few minutes to either land or bail out before the airplane went up in flames.
But I read of an incident in a book I cannot locate right now where that did not happen. I believe it was Don Blakeslee's unit, flying a long range escort mission in the Mustang when one airplane took a hit in the radiator and the pilot prepared to bail out. Blakeslee told him not to bail out but to throttle back and start pumping the primer to inject raw fuel into the engine to keep it cool. It worked, and the pilot flew all the way back to Great Britain, pumping the primer all the way. By the time he got home his glove was worn out and his hand was worn down to the bone, but he made it.
I have wondered why I never read of any other cases of pilots saving the airplane by using the primer. It turns out that the P-51B Mustangs being flown on that mission had manual primers. You grabbed a knob, pulled the plunger out and then pushed it back in. But the later P-51's had electric primers where you pushed on a button for a second or two. I can only assume that the electric primer would not operate after the engine was running, since there would be no reason to use it under those conditions.
In fact, one thing you check very carefully on a light aircraft with a manual primer is to make sure it is locked before takeoff, since having it come loose can cause the engine to quit. One trick in cold weather is to prime the engine and leave the primer open, pulled out, so to increase the fuel flow while at low RPM and keep the engine running until it warms up. Obviously you have to be careful to close it and lock it before taking off.
However I have never read of a Spitfire pilot cooling a Merlin by pumping the primer, even though the pilot's manual for the Mk IX shows it has a manual pump. I wonder if it has to do with the carburetor on the Spits being the float type rather than the Bendix pressure injection carbs used on the American Merlins from the very beginning?
But I read of an incident in a book I cannot locate right now where that did not happen. I believe it was Don Blakeslee's unit, flying a long range escort mission in the Mustang when one airplane took a hit in the radiator and the pilot prepared to bail out. Blakeslee told him not to bail out but to throttle back and start pumping the primer to inject raw fuel into the engine to keep it cool. It worked, and the pilot flew all the way back to Great Britain, pumping the primer all the way. By the time he got home his glove was worn out and his hand was worn down to the bone, but he made it.
I have wondered why I never read of any other cases of pilots saving the airplane by using the primer. It turns out that the P-51B Mustangs being flown on that mission had manual primers. You grabbed a knob, pulled the plunger out and then pushed it back in. But the later P-51's had electric primers where you pushed on a button for a second or two. I can only assume that the electric primer would not operate after the engine was running, since there would be no reason to use it under those conditions.
In fact, one thing you check very carefully on a light aircraft with a manual primer is to make sure it is locked before takeoff, since having it come loose can cause the engine to quit. One trick in cold weather is to prime the engine and leave the primer open, pulled out, so to increase the fuel flow while at low RPM and keep the engine running until it warms up. Obviously you have to be careful to close it and lock it before taking off.
However I have never read of a Spitfire pilot cooling a Merlin by pumping the primer, even though the pilot's manual for the Mk IX shows it has a manual pump. I wonder if it has to do with the carburetor on the Spits being the float type rather than the Bendix pressure injection carbs used on the American Merlins from the very beginning?
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