Spitfire RPM's

[Viper2000]

Originally Posted by icuucme37

When flying the Spitfire without CEM on you can't get full RPM's out of the engine. The automatic engine controls pulls the prop pitch back to 0% and never mover it up to 100% so you can't get max RPM and speed from the engine.

That's what it's supposed to do.

Actually you'll get pretty much full rpm if you climb to operational altitude (ie about 16000-18000 feet).

The Spitfire was not designed to fight at sea level.

[Peril]

Originally Posted by Viper2000

That's what it's supposed to do.

Actually you'll get pretty much full rpm if you climb to operational altitude (ie about 16000-18000 feet).

The Spitfire was not designed to fight at sea level.

Viper, do you have any tested data we can see to verify the rpm v alt curve? This data would add support to any CoD FMs accuracy claims, be good to see it's close to the mark. I've not worked with 'fixed pitch' props in TW FMs, so not much data or first hand experience with simulated fixed props here.

[Viper2000]

Originally Posted by Peril

Viper, do you have any tested data we can see to verify the rpm v alt curve? This data would add support to any CoD FMs accuracy claims, be good to see it's close to the mark. I've not worked with 'fixed pitch' props in TW FMs, so not much data or first hand experience with simulated fixed props here.

Nothing beyond that available to everybody else online:

http://www.wwiiaircraftperformance.o...ane/l1547.html

And yes, I know this is data for a Hurricane. You'd get the same sort of results with a Spitfire, but unfortunately there doesn't seem to be good data immediately available; here is all the Spitfire I stuff:

http://www.spitfireperformance.com/spitfire-I.html

[Peril]

Thanks, that's indeed helpful.

I note that the lowest rpm shown is around 2650 rpm if you extrapolate the graph to SL. This is obviously the high pitch setting, I wonder how much rpm should we see from low pitch at SL? The planes in game currently show a lot lower rpm in fixed high pitch, for what ever reason? The issue that results is that hp is linked to rpm and thus the planes in game with fixed props may be under represented in this area if rpm is low.

Virtual props in Targetware were difficult animals to get functioning realistically, I imagine it is the same here in IL2 FMs.

Thanks again for the data.

[icuucme37]

It don't matter what altitude your at in the Spitfire with out CEM on, you can't get above 21-2200 RPM's.

So I know this is not right. You hit the auto-pilot and it turn 100% pitch and 2800-3100 rpms, airspeed picks up. turn off AP and watch airspeed and PRM's fall like a rock.

[Blackdog_kt]

I know this won't fix the actual issue, but why not fly the aircraft that have a two-position prop with CEM enabled in the meantime? I mean, the prop only has two positions, it's not exactly complicated to use.

Whenever your speed drops go to high RPM, as soon as you pick up enough speed go to low RPM and watch your airspeed increase even more. It's like driving a car with two gears, very simple and it will allow you to fly the aircraft better.

Contrary to popular belief, keeping the RPM at full does not equal full speed. Also, the airspeed affects the kind of RPM you'll get for a given pitch setting, so if you're not using CEM and you have trouble accelerating just point the nose down for a bit to pick up some sped.

It's just that since the prop only has two positions, it will only reach optimal RPM around a very narrow band of airspeeds.

To really solve this problem i see no other way than code an extra routine into the engine "auto-management" that will go to fine pitch whenever the RPM drops too much. I think it shouldn't be that hard, it's just an "IF RPM<2200 THEN pitch=fine" type of statement with a similar one that will force coarse pitch when the RPM picks up a bit, so i guess we'll see it in a patch. Until then, try with CEM enabled and see the aircraft transform from a dog to an actually enjoyable ride

[*Buzzsaw*]

Salute

Two position props were not in general use during the BoB as I have proven in a previous post.

http://forum.1cpublishing.eu/showthread.php?t=21066

All Spitfires I's were converted to Constant speed props starting in late June of 1940, conversions were a matter of a few weeks.

The only relevance for two position props is for scenarios set before the BoB, ie. Dunkirk, interceptions of early recon flights over Britain, etc.