P-51 Engine Overheating at Idle Throttle

[H-var]

Dear Eagle Dynamics Forum,

 

I have attached the replay. Please, look at it and tell me why did the engine become overheated, and how to prevent this in future.

 

Thank you for any advice.

P-51 Overheating Problem.rar

[Bounder]

Hi WoAyumi, I'm no expert but my guess after looking at your track it could be because you ran very high rpms (~3000rpms) and high MP (~40MP) on the ground without moving which causes your coolant temp to rise above safe limit and stay there, followed by your oil temp rising too above limit. The engine stays very hot and you can hear some noises during the track that hint it is not happy. When you throttle up the second time near the end and are still stationary it pushes the engine over the limit and it overheats.

 

Here is the start up guide from the P-51D manual for warming up:

 

-Idle at about 1200-1300 RPM until the oil temperature reaches 40°C and the oil pressure is steady.

-Check the suction gauge to show between 3.75 to 4.25” of vacuum pressure.

-Check all of the engine instruments. Make sure they don’t exceed or fall below their limits.

-After the engine is warmed up, idle at 1000 RPM or slightly less. This keeps the engine clean but not too hot.

 

Simply put the engine is cooled by air moving through the radiators - if you are not moving or are very slow and running high rpms and MP the engine will overheat. Suggest warm up using lower RPM and MP as manual dictates and keep an eye on the coolant temp gauge (left of rpms) and oil temp.

 

That's just my thoughts, hope it is of help, Bounder.

Edited April 3, 2014 by Bounder

[Freddo]

oil pressure, oil temp, water temp, to much manifold pressure, to much rpm, radiator on automode :-(

 

after battery switch on

- check your oil temp, check your water temp,

- set cooling radiators (oil and water) from automatic to fully open (need some time for travel, you can hear it working)

- start engine

- check oil pressure, use "dilute switch" for some time to inject gas into oil if needed (injection time 1 minute or maybe 2 or more in cold conditions)

- give more throttle watch the oil pressure, the water temp and the oil temp, adjust the radiators for faster warm up or let one or both more or less open

- do not wait for long times on the airfield with idle throttle, (the propeller can not deliver enough air flow for your cooling system, give a little bit throttle and it will be stable)

- taxi with open radiators

- after take off and with a good air speed set your cooling radiators to automatik or let it open

- fly with a good setting for rpm and manifold pressure

 

- read the manual

- read it again :-)

 

sorry for my bad english

[Bounder]

- do not wait for long times on the airfield with idle throttle, (the propeller can not deliver enough air flow for your cooling system, give a little bit throttle and it will be stable)

 

What Freddo is saying.

 

The manual states to warm up using 1200-1300rpm until oil reaches 40'C. If you look at your oil temp it reaches 40'C quite quickly and then goes way beyond while you maintain 1300rpm while sitting still. You only need to run up to 1300rpm until you reach 40'C oil, then you should be dropping back the throttle to "1000rpm or slightly less" as per the manual instructions. In your track the oil temp goes above 100'C. This is because you should only use the 1200-1300rpm setting to warm up quickly - you should then be throttling down if you are not ready to taxi and take off (ideally to zero throttle if you are overheating - watch the temps). Your oil temp never reads 0 - that is your oil pressure which drops towards the end because you are damaging the engine. You sit on the taxi way once you are already warmed up and accelerate time - running the engine above limits for about 40minutes of in game time (off the clock). The engine will overheat doing this. Once you are warmed up you should not idle for too long (especially so when running the engine above recommended settings for idling), you should be taxiing and then taking off. You can try opening the oil and water radiator manually (hold switches for ~15 seconds in open position) whilst taxiing to help.

Edited April 3, 2014 by Bounder

[Freddo]

your mission start in normal weather conditions 15°c and more, there is no need to warm up the engine for some minutes.

 

after battery on, open the radiators, start the engine, check oil pressure throttle up until you reach the max oil pressure, dilute for 30 seconds or more to bring the oil pressure down, give more throttle dilöute more if needed, with 40°c oil temp and water you are safe to taxi and take off, dont fly with max manifold and max rpm after take off, check temps set radiators - fly safe

[MariuszDW]

You started at 8:15 and after 30 min you were still idling with cooling set on auto and with time acceleration enabled.

You overheated the engine.

Edited April 3, 2014 by MariuszDW

[Bounder]

Here is a track recording of me warming up and taking off using the mission you uploaded.

 

I start up, run at 1300rpms until the oil temp reaches 40'C and before the coolant temp rises too high. I immediately throttle down once I reach 40'C oil and then I open both the water and oil rads (hold switches for 15 seconds open) before I taxi and then take off to allow 61MP and 3000rpm settings. Once airbourne I raise gear and immediately drop down to 2700rpm and 46MP (You don't have to use max settings for take off but doing it to show it is possible).

 

Hope that is helpful. Bounder.

 

[edit - track too large for upload]

[re-upload should now be attached]

P-51.trk

Edited April 3, 2014 by Bounder

[MariuszDW]

No pedals, so easy on the throttle..

p51-forum-takeoff.trk