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AllorNothing117
03-23-2009, 12:19 PM
Just read a fascinating thread on Radiator settings, shame it was about the 109 so all the initial answers were use automatic! http://forums.ubi.com/groupee_common/emoticons/icon_razz.gif just kidding. Anyway I've been thinking about this for a while. I figured out (the hard way) that it's best to try and cool your engine (60-70% power and open rads with a 75-100% pp) while cruising and then go for optimum speed in combat (80-100% power closed rads and 90-100% pp) am I doing it right?

Also I think that i should be trying to keep the engine at a set amount of revs. Thing is I fly the la7, Spitefire, P-51 and P-38 and have no idea what revs to use in these planes. Is that correct? Any thoughts? Do u know the optimum revs for these planes? Or is it a case of as high as you can without killing the engine?

Hookecho
03-23-2009, 12:29 PM
if you really want to learn to fly the numbers (and in some airplanes this works some its close for the US stuff) check out any US planes -1 manual. there are many places on the web to get such manuals and they will show you the power settings and RPMs for different flight modes at different altitudes. Check out Zeno's Warbirds, they have a bunch.

Each manual should have charts for what settings to use etc as well as GPH estimates for range calulations. What I do is take that info and put them in little charts that I can put in a small binder for my kneeboard I use when I fly

Uufflakke
03-23-2009, 12:32 PM
A lot of this info you can find under Pilot Notes in your pfd Aircraft Guide which is in your IL2 folder.

M_Gunz
03-23-2009, 01:10 PM
Lower revs will do a lot towards running cooler.

AllorNothing117
03-24-2009, 01:57 PM
So should I just always try and keep my revs in the optimum zone?

crucislancer
03-24-2009, 03:17 PM
Speaking of engine management and manuals, does anyone know where I can get the pilots notes for the Hawker Tempest V?

M_Gunz
03-24-2009, 03:18 PM
Optimum depends on the speed you want to fly, the speed you are going and climb, dive or level flight condition.
ADD: and altitude!
I've seen a pilot account in P-47 of leaving power high and controlling speed through revs but it was not complete
instructions, mostly seemed from high cruise to combat. Certainly for landing I want high revs at low power.

Try a long steep dive at full revs all the way then the same dive but once you pass top level speed start cutting
the revs back steadily with speed gain, down to 40 or 50% at top dive speed. Compare the alts you hit 800kph for example.

Conserving fuel, you really want to run lower revs and power, 70%-70% or less, but not where you might get bounced.
Do a search on Lindbergh P-38 fuel and see if you can find how he stretched the combat radius of the P-38 hugely.
IIRC he had them running about 50% rpms for over twice the range, that's how they were able to get Yamamoto.

Tully__
03-24-2009, 04:52 PM
Originally posted by M_Gunz:
Conserving fuel, you really want to run lower revs and power, 70%-70% or less, but not where you might get bounced.
Do a search on Lindbergh P-38 fuel and see if you can find how he stretched the combat radius of the P-38 hugely.
IIRC he had them running about 50% rpms for over twice the range, that's how they were able to get Yamamoto.

He also had them using much more sophisticated mixture control strategies if I recall correctly from the account I read.

Viper2005_
03-24-2009, 05:35 PM
Frictional losses vary somewhere between the square and the cube of rpm.

Supercharger boost varies as the square of rpm.

The best way to cruise at any given altitude is to reduce the rpm until the boost comes down to the value you need to sustain flight at your cruise speed of choice in the lowest supercharger gear you can get away with.

IRL there are various limits as to how far you can take this of course.

As for leaning, theoretically you want to run lean of peak temperature. However, most aircraft lack the necessary instrumentation to do the job.

I would think that it would be possible to have a good go in the P-38 by inferring EGT from the turbocharger instrumentation (IRL).

In the game, just drop your prop pitch and lean as far as you can if you can. Oh and close your radiator!

Tully__
03-24-2009, 08:13 PM
Originally posted by Viper2005_:
As for leaning, theoretically you want to run lean of peak temperature. However, most aircraft lack the necessary instrumentation to do the job.

I would think that it would be possible to have a good go in the P-38 by inferring EGT from the turbocharger instrumentation (IRL).

Several accounts I've read state you can infer EGT from exhaust flame colour, especially on radial engines (mostly because the exhaust stacks are usually easier to see from the cockpit on radials). I've been led to believe by these accounts that not only military pilots but also the flight engineers in the hey-day of the piston engined airliner used this method as either a primary or as a double check that their instruments were reading correctly.
The airlines were particularly keen to get this right as successfully running lean of peak temperature saved them considerably amounts of money in fuel overhead.

jamesblonde1979
03-25-2009, 02:55 AM
Originally posted by AllorNothing117:
Anyway I've been thinking about this for a while. I figured out (the hard way) that it's best to try and cool your engine (60-70% power and open rads with a 75-100% pp) while cruising and then go for optimum speed in combat

Dont forget that water based boost also has a cooling effect on the engine. (MWE)

M_Gunz
03-25-2009, 07:25 AM
Originally posted by Tully__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by M_Gunz:
Conserving fuel, you really want to run lower revs and power, 70%-70% or less, but not where you might get bounced.
Do a search on Lindbergh P-38 fuel and see if you can find how he stretched the combat radius of the P-38 hugely.
IIRC he had them running about 50% rpms for over twice the range, that's how they were able to get Yamamoto.

He also had them using much more sophisticated mixture control strategies if I recall correctly from the account I read. </div></BLOCKQUOTE>

Oh yeah, ran lean at lower throttle is far less hot than same lean at high throttle.
At some point you run cool but almost no power. Back in 69 I remember hearing that a V-8 could run with
almost no pollution but the car would only go about 10 mph. High neat makes the nitrous oxides and like.

AllorNothing117
03-25-2009, 09:57 AM
Damb this stuff is complex! Anyone got like an overview, or learning material, or simplfied version or something. I'm just a simpleton.

M_Gunz
03-25-2009, 10:11 AM
Maybe somebody will post one of those charts that show boost and rpm for different flight modes.
They've been up here before, the historic docs.

Viper2005_
03-25-2009, 02:41 PM
Originally posted by Tully__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Viper2005_:
As for leaning, theoretically you want to run lean of peak temperature. However, most aircraft lack the necessary instrumentation to do the job.

I would think that it would be possible to have a good go in the P-38 by inferring EGT from the turbocharger instrumentation (IRL).

Several accounts I've read state you can infer EGT from exhaust flame colour, especially on radial engines (mostly because the exhaust stacks are usually easier to see from the cockpit on radials). I've been led to believe by these accounts that not only military pilots but also the flight engineers in the hey-day of the piston engined airliner used this method as either a primary or as a double check that their instruments were reading correctly.
The airlines were particularly keen to get this right as successfully running lean of peak temperature saved them considerably amounts of money in fuel overhead. </div></BLOCKQUOTE>

Well you can say that if the flame is yellow you're burning rich, and if the flame is blue then you're probably lean (you might be stoichiometric), but if you want to get best performance you need more information than that.