Warm up or not warm up?

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greybeard

Airman 1st Class
276
43
Oct 25, 2011
During World War II, did fighter pilots generally board their planes with the engines already warmed up by mechanics, or did they do it themselves? Did these procedures vary from one air force to another? If so, what were the practices of the major forces (Luftwaffe, RAF, USAAF, VVS)?
 
During World War II, did fighter pilots generally board their planes with the engines already warmed up by mechanics, or did they do it themselves? Did these procedures vary from one air force to another? If so, what were the practices of the major forces (Luftwaffe, RAF, USAAF, VVS)?

Hi,

Totally dependent on circumstances, but the actual need to "warm-up" also varied with the type and the OAT, or more importantly, the engine/oil temperature before start.
For example, most engines prepared for a scramble cold take-off with oil dilution would not be warmed-up, the ground running would be minimised. But, otherwise, engines would be required to be warmed and run-up before take-off. Whether the warming-up was previously done by groundcrew would be a very variable arrangement.

Eng
 
If I wanted to derail this thread, I could point out the problems of warming up aircraft on an aircraft carrier. This was one reason why the USN wanted open hangars. The RN wanted closed hangars, ideally surrounded by armour. Thus they wanted electric oil heaters in their aircraft.
 
Prior to US fighter pilots climbing into their aircraft and departing on a mission, it would have been normal practice for the ground crews to start the engines and perform a functional checkout, even if not a full power run-up and mag check, no doubt with special emphasis on any reported problems that were supposed to have been fixed. Liquid cooled engines did not need as much warm up as air cooled engines, because the thermostats and engine controls brought the coolant temperature up much faster, but on the other hand that could also lead to sludge and moisture accumulating in the oil because it did not always get hot enough. Of course in conditions of extreme cold special precautions had to be taken.
PBY-ColdBay-Aleutians.jpg


P-38Snow1.jpg
 
Prior to US fighter pilots climbing into their aircraft and departing on a mission, it would have been normal practice for the ground crews to start the engines and perform a functional checkout...
I think so, and that it was not common practice in all air forces. Below, you may see how RAF ground crew jumps into cockpit to start engine while pilot prepares himself.

View: https://youtu.be/zBeKGNCmvWM?si=NnmmZnPYcLY-P80d
Whilst Luftwaffe follows a different procedure:

View: https://www.youtube.com/watch?v=kGHCt0kFc4o
 
Prior to US fighter pilots climbing into their aircraft and departing on a mission, it would have been normal practice for the ground crews to start the engines and perform a functional checkout, even if not a full power run-up and mag check, no doubt with special emphasis on any reported problems that were supposed to have been fixed. Liquid cooled engines did not need as much warm up as air cooled engines, because the thermostats and engine controls brought the coolant temperature up much faster, but on the other hand that could also lead to sludge and moisture accumulating in the oil because it did not always get hot enough. Of course in conditions of extreme cold special precautions had to be taken.
View attachment 841366

View attachment 841365
Man it must've sucked to be stationed in Aleutians. I doubt those "ground" crews got hazardous duty pay.
 
Immediate readiness often saw pilots sat in the cockpit, waiting. If so, they did not jump out and get the groundcrew to start the aircraft. As I wrote before, where cold-start immediate readiness was required, engines were often prepared with oil dilution for quick start and take-off without warm-up. However, where flying was done to a more relaxed or pre-planned program, aircraft preparation might be done with a daily pre-flight servicing that included ground running. An example would be the early Napier Sabre powered Typhoon that needed to be kept warm for use at short notice, ground run every 2hours or so. IMO, it really was a complete mix of possibilities, but you did say fighter pilots, so that narrows it down a bit.

Eng
 
Man it must've sucked to be stationed in Aleutians. I doubt those "ground" crews got hazardous duty pay.

Of course they didn't. USAF firefighters didn't get HD pay until about ten or so years ago, even as we risked our lives in peacetime. I guess it didn't look dangerous to a desk-driver having to defend himself against pointy pencils and the like.
 
I worked with a new hire at Kodak in the 1960s who came from the USN as a photog mate. He told me his Navy job was to be among the first to arrive at an accident to take pictures and grabbed rides on the first firetruck out.
 
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Of course they didn't. USAF firefighters didn't get HD pay until about ten or so years ago, even as we risked our lives in peacetime. I guess it didn't look dangerous to a desk-driver having to defend himself against pointy pencils and the like.

I used to get a pay supplement sometimes (about equivalent of 0.50c a day) for dirty aircraft work "of an unpleasant nature", usually involving being inside fuel tanks or working on toilet installations. A funny thing is, when I later did very dangerous flying work there was no "danger money"!

Eng
 
I think so, and that it was not common practice in all air forces. Below, you may see how RAF ground crew jumps into cockpit to start engine while pilot prepares himself.

View: https://youtu.be/zBeKGNCmvWM?si=NnmmZnPYcLY-P80d
Whilst Luftwaffe follows a different procedure:

View: https://www.youtube.com/watch?v=kGHCt0kFc4o

The Luftwaffe and RAF did do preflight warm ups for planned missions, however, there were "alarm starts" where they had to scramble to intercept inbound enemy aircraft.

Just about all air forces conducted a preflight for planned missions, but when the enemy drops by unannounced, procedures change.

A good example would be the USAAC aircraft at Pearl Harbor - they had zero notice to get going and it was a mad dash to get their aircraft underway, several pilots were still in their nightclothes.
 
Immediate readiness often saw pilots sat in the cockpit, waiting.
And the P-39 tended to overheat when left idling; not a surprise when you see those tiny wing root air intakes, which could not have allowed much propwash into the radiator. Then again, in the the Russian winter that might have been an advantage.

On the other hand the lack of a big engine up front, leaking all kinds of hot air back meant that the P-39 was not noted as being comfortable in cold weather. Cold air leaked into the cockpit very easily and they even took to using canvas tent pole covers over the nose gun ports to try to keep it out. It looks like the example below might just have that mod. Of course, in Russia they must have been delighted just to have an enclosed cockpit.

I at first figured this must be a shot from the flightline at Buffalo, but looking at the background it must have been in AK. I hope the guy stuck in the window did not lock himself out.
air_airacobra10.jpg
P-39Ad1943-1Mod.jpg
 
Can anyone make out what was originally painted on the cockpit door?
 
Prior to US fighter pilots climbing into their aircraft and departing on a mission, it would have been normal practice for the ground crews to start the engines and perform a functional checkout, even if not a full power run-up and mag check, no doubt with special emphasis on any reported problems that were supposed to have been fixed. Liquid cooled engines did not need as much warm up as air cooled engines, because the thermostats and engine controls brought the coolant temperature up much faster, but on the other hand that could also lead to sludge and moisture accumulating in the oil because it did not always get hot enough. Of course in conditions of extreme cold special precautions had to be taken.
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View attachment 841365
When my Old Man was stationed in Iceland patrolling the Denmark Strait, the Hampdens carried an engine man for field maintenance if required. The airmen had to dig trenches for the main-wheels and roll the aircraft forward into them, then burying the main wheels of the Hampden and tie-ing down. All went well. Except for a very large tent accomodating Americans which rolled up the hill, with them inside it. Out on the fjord a 210 Squadron Catalina spent 24 hours motoring up to her mooring buoy. can't say whether is was floats down or not. For water take-offs in bad weather, they retracted their floats first and picked up the floats with aileron
 
a. Re-start and fly - all radial engines needed to be turned by hand "6 blades" to make sure that there is no "hydraulic lock". "Hydraulic lock" was created when engine oil sipped through the piston rings down into the lower cylinders' combustion chambers. If enough oil was accumulated in any of these cylinders, the movement of the piston was blocked (oil doesn't compress) resulting in a bent connecting rod and the ruining of the engine. Had a "hydraulic lock" been discovered, the front spark plug of the suspected "Locked cylinder" would be removed, thus allowing the trapped oil to drain, removing the lock. So, "instant" launch of radial engined aircraft without first turning the engine by hand was not done.

b. Re-warming up - it takes a long time to bring the engine temperatures of a B-17, for example until they are "in the green", when the application of power above about 900-1000 RPM (warming up power) is allowed. I read someplace that the B-17s ground crews would run the engines prior to a mission to warm up the engines and more importantly to make sure they run well.

c. In his book The Big Show, Pierre Clostermann, the great French fighter pilot, descibes his time flying Typhoons equipped with sleeve valved Sabre engines during the winter of 1944. To keep the engines from freezing (oil gelling between the sleeve and the engine block so thick that the sleeve would not turn), the mechanics kept the engines running all night long!
 
In the Poltava Affair about the Frantic operations, when the pilots from the 357th were there they saw the Soviet pilots scramble and take off. They jumped in their P39s, started them up and immediately poured on the coals and took off. They didn't do any preflight checks, warm up, even see if they had enough fuel. This had the US pilots somewhat amused.
 

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