Did real aircraft engines overheat at military power?

[GScholz]

You're not consistent. If the cooling effect is better at low alts than high alts the P-38 should have had even more difficulty keeping the engines warm at low alts.

[GScholz]

If we use the standard atmosphere as reference the temperature at SL is 15C and the air density is 1.26 Kg/m. At 25,000 feet the temperature is -35C and the air density is 0.55Kg/m. While the amount of air passing through the radiator is about halved the temperature of that air has dropped 50C (100C is the boiling point of water, 0C is the freezing point of water). While I could easily stand naked in a light breeze at 15C I would quickly become an ice popsicle at -35C even at half the air density and even without wind.

[Scootter]

Originally posted by GScholz
You're not consistent. If the cooling effect is better at low alts than high alts the P-38 should have had even more difficulty keeping the engines warm at low alts.

G.. I'm sure you have heard of cowl flaps, they are used to control the amount of air flowing into and out of the cooling system and I am sure the cooling system in a liq. cooled engine also had a thermostat much like a car.



at slow air speeds the lower air flow is a greater problem and some warbirds now have water spray bars added

Here read up on a Hurricane it has a liq. cooled inline


part one
http://www.avweb.com/news/columns/185674-1.html

part two
http://www.avweb.com/news/columns/185849-1.html


I hope to be consistent if nothing else

[Scootter]

Originally posted by GScholz
If we use the standard atmosphere as reference the temperature at SL is 15C and the air density is 1.26 Kg/m. At 25,000 feet the temperature is -35C and the air density is 0.55Kg/m. While the amount of air passing through the radiator is about halved the temperature of that air has dropped 50C (100C is the boiling point of water, 0C is the freezing point of water). While I could easily stand naked in a light breeze at 15C I would quickly become an ice popsicle at -35C even at half the air density and even without wind.

ahhh but you are not making 1200 hp

if you were fine and comfortable and properly clothed and running a long distance and I reduced your cooling system by half by adding clothing to you, what would happen

and you have just reduced the cooling system by 50% by your own math


you need to understand it is air molecules that carry away heat, in space an air cooled engine would overheat and is real cold out there

[GScholz]

The powerplant problems were not entirely the Allison engine's fault. Many of the reliability problems were actually due to the inadequate cooling system, in particular the cumbersome plumbing of the turbosupercharger intercooler ducting which directed air all way from the supercharger out to the wingtips and back. In addition, the lack of cowl flaps were a problem. In the European theatre of operation, temperatures at altitude were often less than 40 degrees below zero and the Lightning's engines would never get warmed up enough for the oil to be able to flow adequately. Octane and lead would separate out of the fuel at these low temperatures, causing the Allisons to eat valves with regularity, to backfire through the intercooler ducts, and to throw rods, sometimes causing the engine to catch fire.

These problems bedeviled the Lightnings until the advent of the J version with its simplified intercooler ducting and the relocation of the oil cooler to a chin position underneath the propeller spinner. When the P-38J reached the field, the Allison engine was finally able to attain its full rated power at altitude, and the engine failure rate began to go down.

http://home.att.net/~jbaugher1/p38_17.html

[Sled]

While I could easily stand naked in a light breeze at 15C

Hey now! No one needs to be taking thier clothes off!

[GScholz]

*lol*

[Scootter]

added to last post please reread

[GScholz]

*LOL* What you need to understand is that you are not in space at 25K feet. You have 50% of the air molecules, but those molecules are considerably cooler than at SL and carry away a greater amount of heat than the 100% amount of hotter molecules at SL.

The P-38 did not have any problems with keeping the engines warm at low and medium altitudes, but at high altitudes it did. QED.

[Mister Fork]

This whole post is generally asking Pyro to code into the sim engine overheating/overcooling depending on several factors:

a) Altitude
b) Aircraft type
c) speed

Let's throw in the fact you'll need to add cowl flaps to address heat issues.

Hmmm, I'm with Pyro on this, KISS - keep it simple stupid.  WEP works just great - it's simpler and easy to manage.

[GScholz]

Originally posted by Scootter
you need to understand it is air molecules that carry away heat, in space an air cooled engine would overheat and is real cold out there

Not necessarily. It would depend on how much of the heat is radiated out into space. If the engine was in a shadow (not in the sunlight), the engine might very well freeze solid.

[BenDover]

An engine wouldn't work in space ;p

[Scootter]

Originally posted by GScholz
*LOL* What you need to understand is that you are not in space at 25K feet. You have 50% of the air molecules, but those molecules are considerably cooler than at SL and carry away a greater amount of heat than the 100% amount of hotter molecules at SL.

The P-38 did not have any problems with keeping the engines warm at low and medium altitudes, but at high altitudes it did. QED.

You describe a cooling system that was poorly designed and had a problem with allowing the oil to warm up, yet you insist on using that to somehow convince me as to the laws of thermal dynamics and to the lower cooling ability of lower air density (by the way it is less then half the air density at 30k feet more like 80% less).

I have first hand knowledge of this and have flown as pilot in command many times in the low 20's and have seen both higher EGT and CHT levels higher with altitude as well as TIT rise on the turbo. I have opened the cowl flaps a bit and added mixture as well as lowering MP to help keep them in limits.

I will say it has been fun playing, have a good day and regards friend:)

[GScholz]

With oxygenated fuel and a bit of modification it would.

[BenDover]

Someone say TITs???