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=FI=Murph
Feb-22-2014, 11:44
I don't know if this is something that is already being worked on. I was flying on my own server with a couple of friends last night. We are getting to know this game and were just trying different things.
We decided we would fly up to about 20,000 ft in our Spit 1as to have a look at how the contrails were rendered (beautiful BTW). When we got up above 16-18M ft we found that we needed to run with full-fine prop pitch and full rich fuel mixture in order to keep the engine from blowing up. This seems to be the exact opposite of real life? In a real aircraft with a carborater, the mix would need to be very leaned out to keep the proper ratio of fuel to air, and the prop pitch would need to be coarse to work efficiently in the thinner air, wouldn't it?

Haviland
Feb-22-2014, 13:15
What do you mean by "blowing up"? Overheating?

I am assuming that your radiator flap is fully open. I have never been advised to take the Spitfire off of auto-rich (the default setting) at any altitude (barring up near the service ceiling perhaps). You can manually lean, but you also need to make sure you're running at relatively low power (cruise). From the charts that I have looked at, leaning in the Spitfire was only done at very low boost pressures (from anything negative up to about +1.7) for absolute max endurance.

I've run at almost all normal power settings and RPM settings up to about 25,000 feet in the Spit Ia and IIa, and I've generally never had a problem with overheating to the point of wrecking the coolant line. If anything, running at 3000 RPM ("full fine" with the Rotol CSU) at that height will contribute heavily to overheating the engine. I typically don't run anything greater than 2700-2750 between 15-25k feet, as the water temps tend to rise to about 115* at that altitude with the governor set to anything higher.

I cruise at 2400 RPM and whatever max boost pressure is available up to +4 (at 20-25k feet this would mean maybe ~0, +1). At any altitude I can go 35-50% on the radiator with those settings and not blow the engine.

Actually, it might be that you're running it manually on rich (coming off of manually lean, a setting which would cause problems if not high enough and if at higher power settings) instead of on auto-rich. A manually set fully rich mixture at that altitude might (should) lead to problems at lower power settings / RPM settings.

Of course, someone more enlightened than myself can probably speak with more precision to your issue. I myself am still learning some of the more intricate aspects of engine management, so take the above with a grain of salt.

=FI=Murph
Feb-22-2014, 16:12
Thank you, that's actually very helpful. I didn't know that leaving the mixture at full rich meant it was in auto rich, I thought it needed to be manually leaned. Is the Rotol the same as a constant speed prop for our purposes? I usually like to stay in the 22-2400RPM range with the radiator about half open, but we noticed that at higher altitudes it ran fine at 2700RPM. I'm still new at this, though I have many years of Il2 under my belt. We're having a great time getting to know this sim, now that it's been largely brought up to "release status" thanks to Team Fusion.

Haviland
Feb-22-2014, 18:00
Yeah, the default setting is auto-rich so you don't need to manually lean or really worry about mixture settings. When I first started flying in CLOD, I was worried about mixture too but someone told me to just leave it at auto-rich and the mixture will take care of itself. You can manually lean it, but I've only ever heard of people doing it at very high altitudes (25kish) with very low power/RPM settings to save fuel. Of course, in real life I am sure that pilots leaned it more often, but I am not sure how the mixture settings are modeled in game, and for that reason I generally stay away from actually consulting the tables (the very few I can find) from that era on mixture and power settings at given altitudes.

The Rotol is the constant speed prop, correct. The other is a two pitch (fine or coarse), and I think there was even a wooden fixed-pitch propeller very early with the Spit and the Hurricane (not sure if this is in game).

RAF74_Buzzsaw
Feb-23-2014, 16:09
What do you mean by "blowing up"? Overheating?

I am assuming that your radiator flap is fully open. I have never been advised to take the Spitfire off of auto-rich (the default setting) at any altitude (barring up near the service ceiling perhaps). You can manually lean, but you also need to make sure you're running at relatively low power (cruise). From the charts that I have looked at, leaning in the Spitfire was only done at very low boost pressures (from anything negative up to about +1.7) for absolute max endurance.

I've run at almost all normal power settings and RPM settings up to about 25,000 feet in the Spit Ia and IIa, and I've generally never had a problem with overheating to the point of wrecking the coolant line. If anything, running at 3000 RPM ("full fine" with the Rotol CSU) at that height will contribute heavily to overheating the engine. I typically don't run anything greater than 2700-2750 between 15-25k feet, as the water temps tend to rise to about 115* at that altitude with the governor set to anything higher.

I cruise at 2400 RPM and whatever max boost pressure is available up to +4 (at 20-25k feet this would mean maybe ~0, +1). At any altitude I can go 35-50% on the radiator with those settings and not blow the engine.

Actually, it might be that you're running it manually on rich (coming off of manually lean, a setting which would cause problems if not high enough and if at higher power settings) instead of on auto-rich. A manually set fully rich mixture at that altitude might (should) lead to problems at lower power settings / RPM settings.

Of course, someone more enlightened than myself can probably speak with more precision to your issue. I myself am still learning some of the more intricate aspects of engine management, so take the above with a grain of salt.

The only time you should switch to auto-lean is when your boost is +1 or less, and your rpms are 2600 rpms or less. Any other situation you should use auto-rich.

If you switch to auto-lean in higher rpm or higher boost situations, you are in danger of destroying your engine very quickly.

I would recommend all new players take the time to read the Team Fusion Wiki page and the aircraft manuals there:

http://www.theairtacticalassaultgroup.com/wiki/doku.php?id=start