Originally Posted by JtD (Post 489851)

Never said that. Physics always apply. I said:
- basic principles of heat exchangers don't fully explain general aircraft engine oil temperatures
- general aircraft engine oil temperature characteristics don't fully explain Spitfire specific oil temperatures

That means, while it is comparatively easy to estimate the heat exchange in the radiator for a given set of conditions, this is just one piece of the puzzle of oil temperature calculation.

Originally Posted by JtD (Post 489851)

Never said that. Physics always apply. I said:
- basic principles of heat exchangers don't fully explain general aircraft engine oil temperatures
- general aircraft engine oil temperature characteristics don't fully explain Spitfire specific oil temperatures

That means, while it is comparatively easy to estimate the heat exchange in the radiator for a given set of conditions, this is just one piece of the puzzle of oil temperature calculation.

Originally Posted by NZtyphoon (Post 489934)

Other aspects to be considered: coolant used; efficiency of coolant flow; thermal efficiency of engine/engine components, mechanical efficiency of same, etc etc

http://www.freestudy.co.uk/thermodynamics/t4201.pdf

Originally Posted by Crumpp (Post 490029)

Ahhh, Spitfire physics!! Maybe research at the LHC will one day be able to explain it?

Originally Posted by bongodriver (Post 489602)

OK then:

if you climb at constant airspeed then true airspeed increases with altitude, at constant indicated airspeed the 'mass' of air flowing through the cooling system remains constant with the added effect of reduced ambient temperatures.
penalties of high altitude on performance are not really a factor, bottom line is if you keep the same amount of air mollecules passing through the cooling system then you won't have problems cooling, I'm not entirely sure where crumpp gets the theory that maintaining constant indicated airspeeds is not possible but everyone else understands that a constant reading on the airspeed indicator means constant indicated airspeed and we also know how to achieve it.
To some extent engine temperatures will also fall off with the natural reduction of power with altitude also.


Oh and :rolleyes:

Looking forward to the next installment from the Nonsensical Administration of Crumpp Aeronautics

p.s. I'll post you a picture of what high altitude shows on the Learjet PFD tonight as I have an empty sector back from Denmark tonight.

Originally Posted by NZtyphoon (Post 490040)

Ahhh, crumpp troll! Maybe research at the Trolling Academy will one day be able to explain crumpp?

Originally Posted by JtD (Post 489610)

It's not a Crumpp problem here. The generalizations are pointless.

Indicated air speed is not equivalent to mass flow, because there's a square root over density in the IAS calculation. At a constant IAS, mass flow goes down with altitude. WW2 aircraft generally achieved lower IAS's with altitude, so mass flow goes down even more. This is countered by the reduced temperatures at altitude.

Now you can argue all day about the net effect, but unless you come up with a statistically significant number of test results, it will remain pointless. What remains is an unnecessary exchange of rudeness, which I think this forum has seen enough.

Originally Posted by Dirkan (Post 487852)

Hi!

Has anyone tested the exact oil temperature at which the engine will break?
Or perhaps too much boost in combo with RPM, regardless of oil temp?
The radiator always breaks at 120 Celsius, 10/10 times, however, the oil temp is a bit more elusive.
(I don't give a rats ass about the pilot notes)

Thanks in advance :)