P40 cowl flaps lever (and further insights about engine heat)

[19//Moach]

Having observed the ratchet-like mechanism visibly built into the cowl flaps control lever in the P40 cockpit, and having counted the notches on the locking rack of that mechanism, it is clear that the operation of that lever should be in discrete increments of 6% - not continuous movement, as currently depicted in the sim

 

this would allow some 5 position between neutral (30%) and closed, correctly matching the number of teeth on the ratchet locking rack gear (that crescent-shaped thing under the lever)

 

seeing that the spitfire does operate correctly in this same regard, with accurately modelled 20% increments to it's radiator - it seems fitting to observe that the P40 should indeed feature this same behavior, only with an increment of 6% instead.

 

 

one of many little details that make the whole of a great simulation.

 

thank you

Edited July 27, 2017 by 19//Moach

[BlitzPig_EL]

I'd rather that it actually performed like the real thing.

[19//Moach]

well, that's an understatement.... 

 

but aerodynamically, it already been brought up and thoroughly discussed... let's see how 2.012 treats it

 

 

yet nobody had ever pointed out the incorrectly continuous movement of those cowl flaps - which is why I'm calling it out here

 

 

needless to say - the whole engine heat model could use reworking... currently all engines overcool (especially on the ground)

 

I'd even suggest, the artificially imposed "boost timers" would be wholly obsolete if only the engine temperatures were correctly modelled.  if engines would overheat over these same "time limits", then damage should ensue as a natural consequence of that.

 

this would make significantly more sense than the way it is now

 

 

and I mean this for every plane. though it is the most obvious on this one, I think

Edited July 27, 2017 by 19//Moach

[-=PHX=-SuperEtendard]

But if you have engines which it's radiators can keep up with the heat generated by the emergency power then they wouldn't have any sort of regulation.

[19//Moach]

But if you have engines which it's radiators can keep up with the heat generated by the emergency power then they wouldn't have any sort of regulation.

 

that's my point: at such high power settings, they should not be able to

 

 

the current heat model is wrong, and because of that, they need to impose nonsensical time limits.... these would not be necessary if not for the overcooling problem, since the "timer" would be enforced by the natural amount of time it'd take for a hot-running engine to overcome the radiator's cooling potential

 

that is the real reason those time limits were stated in the first place...  (that and cumulative damage over many flights, which doesn't apply to the sim, of course) 

Edited July 27, 2017 by 19//Moach

[JtD]

Typically, these engines didn't exceed water, oil or cylinder head temps (the three temps we can monitor) when running full power in level flight on a standard summer day with radiator closed/flush position. The radiators were designed to deal with adverse conditions - hot days, slow flight, thin air, high power output. There's plenty of data available. Your real reason is nonsense.

 

Edit: Adding the game-real life comparison for the Yak again. The engine's running hotter in game.

Edited July 27, 2017 by JtD

[ZachariasX]

The P-40 cowl shutter moves in a continuous way, unlike the Spitfires with its disceete positions. It just features marks of certain positions, like least drag etc. The lever works as it should.

[ZachariasX]

Typically, these engines didn't exceed water, oil or cylinder head temps (the three temps we can monitor) when running full power in level flight on a standard summer day with radiator closed/flush position. The radiators were designed to deal with adverse conditions - hot days, slow flight, thin air, high power output. There's plenty of data available. Your real reason is nonsense.Edit: Adding the game-real life comparison for the Yak again. The engine's running hotter in game.

Interesting chart. I always thought that we are working a little much with the rads in this game (in "normal" weather). For many aircraft, the slightly opened radiator gives least drag. And this position is meant for flying. In the Spit, there is the "40% position", in other aircraft such as the P-40 and the P-47 positions are marked with red or white lines. If one operates the aircraft in regular flight modes, there is no change needed in this setting. In fact, opening rads more increases drag such that flightspeed drops enough to decrease cooling efficiency.

 

If temps increase too much, usually one is flying too slow. Typically in an excessively steep climb. The Spitfire (especially early marks) is very sensible to that. Opening rads if engine temp is too high is even counterproductive. It will slow you down further, canceling the added cooling effect. You can close rads however in dives from altitude to not let the engine overcool. But a fully closed rad often has more drag than a flush opened one.

[19//Moach]

curious that it can run hotter in flight, but on ground all engines will overcool, even with everything shut on a summer day.... 

 

there's definitely room for improvement there...

 

 

as for the less efficient cooling with the rads full open, it also has to do with duct pressures (or so I hear) - as in, higher pressure means there is more air in the radiator to transfer heat onto, so to an extent, having them fully open would have a somewhat less than obvious result, due to the lower pressure inside

 

 

either way - the current "timer based model" is woefully unfit for a simulator such as this...  might as well have a health bar to go with it, so gamey it is

Edited July 27, 2017 by 19//Moach

[JtD]

If temps increase too much, usually one is flying too slow. Typically in an excessively steep climb. The Spitfire (especially early marks) is very sensible to that. Opening rads if engine temp is too high is even counterproductive. It will slow you down further, canceling the added cooling effect. You can close rads however in dives from altitude to not let the engine overcool. But a fully closed rad often has more drag than a flush opened one.

Obviously, in a climb, you can open the radiator without slowing down, increasing cooling capacity. You'll just have to reduce the climb angle while maintaining the same speed, decreasing climb rate.

 

The lack of overcooling issues in game takes away quite a bit from engine management. If statements like 'keep temperature between 70 and 85' were to be taken seriously, you'd certainly have to pay a bit more attention.

[ZachariasX]

Obviously, in a climb, you can open the radiator without slowing down, increasing cooling capacity. You'll just have to reduce the climb angle while maintaining the same speed, decreasing climb rate.

In the baby Spit (Mk.I & II) it is advised not to open rads in climb but gain speed instead and climb at a shallow angle. If you're flying level or dive, you can cool the engine quickly when opening the rads. Usually, when people start a much climb below 240 mph, they will remain in sort of a "coffin corner", cooling whise. The plane will use too long to get sufficiently fast and the engine will start cooking. if you open the rad more, it takes you stay so slow that you are tempred to use excess climbing power making the engine cook even more despite a more open radiator.

 

 

The lack of overcooling issues in game takes away quite a bit from engine management. If statements like 'keep temperature between 70 and 85' were to be taken seriously, you'd certainly have to pay a bit more attention.

With cool shocking ou can kill an engine rather quickly. Besides pre-detonations with significant overboost, it should be one of the quickest way to kill an engine. Especially radials. But while everyone is crying about restricted power output / "engie timers", people are very relaxed about diving, even in russian winter.

[Venturi]

Yes, I agree that overcooling is not modeled well. To effectively calculate rate of change of temperature of water-based coolant, roughly:

 

delta temp of coolant (deg/sec) = {[(engine power * coolant absorption efficiency) - (radiator efficiency * coolant absorption efficiency * airspeed * air density)] * [constant * (ambient temperature-coolant temperature)]} / [(specific heat of water * mass of coolant) + (specific heat of aluminum * mass of engine block)]

 

Excess heating not captured by coolant absorption efficiency would be transferred to oil temp which uses similar calculation, with much smaller specific heat.

 

For this reason also, radials have much higher delta temp possibilities for given airflow (denominator much smaller). This is also the reason why their parts clearances are larger (because the engine must be able to operate at a much higher range of engine temperatures than a water cooled engine).

Edited July 30, 2017 by Venturi