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View Full Version : Prop pitch on Me109 planes messed up big time!



carguy_
06-08-2004, 05:24 PM
I can`t believe it!

It`s the third time my engine cooked on auto prop pitch in a dive!There wasn`t any overheating.

On pre 1943 Me109 pp seems to be ok below 2700RPM but this isn`t guaranteed.Also with auto prop pitch!

On 1943 and newer Me109 auto prop pitch stays at 2400RPM at 100% power!But when I go for manual and stay at 2700RPM the engine gives power for around 10mins and completely dies.

I`m totally lost because the engine seems to accept relatively high RPM(2700-2800) but it dies at moments it chooses.

Overheating - tested in 14 missions and only 2mins of overheating(100%power,no WEP) causes HEAVY performance loss.Engine enters agony!


I have never had much trouble with pp be that manual or auto.After applying the patch the plane dies at 100% power on manual/auto.

There must be something wrong here!

I have few trks,long though.Anybody wants them just say it.

http://carguy.w.interia.pl/tracki/sig23d.jpg

carguy_
06-08-2004, 05:24 PM
I can`t believe it!

It`s the third time my engine cooked on auto prop pitch in a dive!There wasn`t any overheating.

On pre 1943 Me109 pp seems to be ok below 2700RPM but this isn`t guaranteed.Also with auto prop pitch!

On 1943 and newer Me109 auto prop pitch stays at 2400RPM at 100% power!But when I go for manual and stay at 2700RPM the engine gives power for around 10mins and completely dies.

I`m totally lost because the engine seems to accept relatively high RPM(2700-2800) but it dies at moments it chooses.

Overheating - tested in 14 missions and only 2mins of overheating(100%power,no WEP) causes HEAVY performance loss.Engine enters agony!


I have never had much trouble with pp be that manual or auto.After applying the patch the plane dies at 100% power on manual/auto.

There must be something wrong here!

I have few trks,long though.Anybody wants them just say it.

http://carguy.w.interia.pl/tracki/sig23d.jpg

El Turo
06-08-2004, 05:29 PM
We seem to be dance partners today! http://ubbxforums.ubi.com/images/smiley/16x16_smiley-very-happy.gif


The problem you're running into during your power-on dive is that the governor system that limits your prop RPM has a minimum angle to which it can lower the prop-angle versus the oncoming wind. At that point, the prop becomes like a big windmill because it just can't make the angle any shallower and the oncoming air-resistance/drag makes the prop overspeed even if it doesn't really want to.

Kind of like if you set the cruise-control in your car and then go down a 20% grade.. it's going to accelerate regardless of where you set your cruise control because the forces acting upon it are beyond its ability to negate.

I believe that's the problem you're running into?

How fast are you going before it pops?

Are you pulling your power out all the way or leaving the throttle in?

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Cragger
06-08-2004, 05:58 PM
It would be a maximum angle BTW. Less of an angle would increase prop rpm not decrease it.

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Agamemnon22
06-08-2004, 06:11 PM
Well this is the nature of the beast. Don't let your engine over 3000 for more than a second or two no matter what, and don't let it sit above 2700 for any significant length of time.

carguy_
06-08-2004, 06:22 PM
You mean the wind makes auto prop pitch go over critical RPM even if it doesn`t want to?
In G2 the engine cooked @500km/h,2600RPM.Maybe this is the case afterall,but why haven`t I cooked one engine since FB came out until today?

There must be something wrong,I tell ya.

http://carguy.w.interia.pl/tracki/sig23d.jpg

lbhskier37
06-08-2004, 06:29 PM
should be possible in any plane. Has never seemed posible though.

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Flightvector
06-08-2004, 06:33 PM
Was your plane damaged in any way? A hit to the governor area often screws up the prop pitch mechanism and makes your RPM run away. It happens easily in Hurricanes and you hear the RPM shooting up, alhough I have had this happen in many fighters as well.

H_Butcher, interesting how you mention there may be a limit to the governor's ability to maintain RPM. I would think that the auto pitch mechanism could bring pitch to feather (90 degrees or parallel to airstream) in which no amount of speed could even cause the prop to turn. But I have no idea if the 109 could in fact do this, I'd be surprised if this was the case though.

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El Turo
06-08-2004, 07:19 PM
Cragger.. I was referring to the relation to the oncoming wind, not a technical description of "prop pitch". But thanks for the heads up.

http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif

Most props have a limit as far as how much travel the prop-blades actually have. Once you've reached that limit there's just nothing else that can be done by the governor system.

Callsign "Turo" in IL2:FB & WWIIOL
______________________
This place
was once
a place
of worship
I thought,
reloading my rifle.

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WUAF_Badsight
06-08-2004, 10:32 PM
i rev Bf-109s to over 3000 rpms all the time climbing i get overheat only after the temp has gone up

not simply because i used over 3000 rpms

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IL2-chuter
06-09-2004, 02:23 AM
All German propellers were electric and fully featherable. As a side note, notice how many pictures there are of Mistels after the war with 190 (and sometimes 88) canopies jettisoned loose and props feathered. GI's were climbing in and crankin' knobs, pushin' buttons and movin' levers in most planes till someone got control of them and/or the aircraft. I would have loved it! http://ubbxforums.ubi.com/images/smiley/16x16_smiley-happy.gif

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RedDeth
06-09-2004, 02:38 AM
late 109s especially k4 on manual cook engines exceptionally easy now. too easy. you can fly safe and keep your revs down and still eventually the engine frys quite often. most people have given up flying the k4 due to this. its much too touchy to try to push any power out of it. its fine on auto.

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carguy_
06-09-2004, 02:52 AM
Yeah,but Keeping the engine at 2400RPM is a joke.I`d say Me109 loses about 15% of power that way.

I hate to say it but after the patch I feel just like it was in IL2 days.

EDTI:In one of the trks engine dies @2700RPM,570km/h and "Overheat!" message appears for 2 seconds.It looks as if FB counts seconds of overheat message and when the limit is exceeded,engine dies.The funny thing is that it sums up all overheat messages.In all of my trks I had multiple overheat messages only because of engine temp,not overrev.It`s obvious that everytime I opened flaps and lowered throttle which led to "normal" message but it doesn`t seem to matter.

http://carguy.w.interia.pl/tracki/sig23d.jpg

[This message was edited by carguy_ on Wed June 09 2004 at 03:28 AM.]

michapma
06-09-2004, 04:53 AM
Engine damage is complicated in real engines, we are left to speculate how it is modeled in FB. Important are not just rpms but also manifold pressure, in 109s measured with in ATA.

It's true that the windmill effect at high airspeeds can cause the engine to overspeed. It is the engine rpm and manifold pressure that are important. Keep in mind that more than engine rpm is involved in the damaging of real engines, and we don't know what all is modeled in FB.

To be blunt, if I were your flight officer I would ground you for not adhering to the piloting instructions. Unless I'm quite mistaken, Luftwaffe pilots did not put the engine into manual prop pitch control to get more power from the plane. If you play with the system, then you have to accept that you can get burned; you don't have any historic precedent behind your arguments.

If your engine is burning up on automatic control in a high-speed dive, that's another thing and I as your groundcrew chief recommend limiting your dive speeds. http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

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