Here is an illustration of what I understand Steinhilper to be talking about;
http://s18.postimage.org/4wlow6b2v/s..._technique.jpg

oscillate, change, vary, etc..

A rose by any other name! ;)

In summary, the word 'maintain' is not a rose! It is more of a turnip in Crumpps analogy! ;)

The rpm will vary and in a manual selectable pitch propeller, the pilot has to adjust the pitch to maintain rpm.

Hmmm... Just wondered about one thing with this prop pitch thingy...

How about early Hurricane and Spits with 2-stage pitch?

Should'nt they have the same "clutch pop" benefit as some of us are speculating about Bf109?

As You are flying at top speed with fine pitch and you kick in the coarse pitch for a short time should it make a little jump in Spit/Hurri before the speed starts to decline?

Related - at lower altitudes, Merlin engines developed at least as much power at 2850 rpm as they did at 3000 rpm (depending on source). Below full throttle altitude, climb was to be done at 2850 rpm, while at high altitude, above full throttle altitude, these rpm were to be increased to 3000 rpm. Just like with any other engine, it increased boost and engine power. However, the handbook said to always fly at these 3000, not change pitch back and forth. No idea if pilots ever tried that.

With the two stage pitch, it would probably be too hard to get the timing right to make it an efficient, practical option, though maybe pilots on occasion had to employ a similar scheme - with high rpm being too high to sustain and low rpm being too low for sufficient power output.

Not modelled in Cliffs of Dover, but apparently the BoB Spit pilots discovered that with the 2-speed props they could manipulate the pitch control lever in the center of its travel and get a variable pitch response, which they used to great effect in optimizing performance.

This is not to be confused with a Constant Speed Propellor, which to a great extent could maintain a desired speed (rpm) by automatically adjusting the pitch in response to throttle (boost) settings or aircraft maneuvring. The 2-speed prop, even at intermediate pilot-manipulated settings, would change rpms at different throttle settings and different changes in plane maneuvring, and thus bear careful watching (and listening).

This little trick pre-empted the need or desire to abruptly shift from Full Coarse to Full Fine (and vice versa).

Well of course, this is how it usually works. BUT in this specific scenario (109E way above FTH) the pilots decided to change the rpm almost constantly up and down to get better performance, where their engines and supercharges struggled a bit. So they were adjusting the pitch almost constantly to mainatin speed. So you accelerate a bit by overreving the engine, but you won't be able to keep the speed just by 'adjusting the pitch to mainain rpm' (which is normally enough, say below FTH and this is where you are wrong or failing to understand what the big deal here is), they had to adjust it soon enough the opposite direction (=up) to overrev a bit and accelerate. As you see the trick is based on repeating the process constantly, hence changing the rpm constantly, not maintaining it. Just maintaining the rpm it would make them fly slower up there. The mechanism was based on the supercharger rpm.

So you say maintain rpm, Steinhilper says keep working on it constantly. I don't think you're saying the same thing. What you're saying is pretty obvious and this procedure is only mentioned because it is interesting and on topic of prop pitch (rpm) and supercharger at specific condition = high altitude.

Only issue is that is not what the man says.....

He does not say a thing about changing rpm. He says to constantly manage the pitch.

That is what you have to do in order to maintain rpm!!!

The pitch must be constantly adjusted to maintain rpm as the speed increases!

;)

If you type it in bold it doesn't make it right. ;) I am not saying you're wrong here (you're not saying anything new here re angine management), you're just completely missing the whole point of this conversation (that is non standard pitch management at high altitudes as described by a LW pilot who has actually been there).

What you're trying to do here is instead of contributing to an interesting topic or even discussing it, you're doing everything possible to prove that you, Crumpp, were right even if you used wrong semantics and therefore said something completely different to actual WWII 109 pilot.

If you're saying that Stainhilper was actually maintaining the rpm even though he was working with the prop pitch lever to get more rpm (here is the catch!) to get a boost from his supercharger above FTH, then you're obviously right and he was maintaining his rpm by rising his rpm for short periods of time.

ummm... So he was only shifting his supercharger rpm? could you please explain to me how he did that.

He does not say or do anything "non-standard". He just explains the right way to manage the pitch on the propeller is to constantly change it.

That is why you hear the pulsing of the pitch change. You hear that at any governor check on run up of a CSP equipped aircraft.

Oh yes he does indeed. Below the fth there was no point in overreving the engine for a speed gain. At higher altitudes, there apparently was. As I said, you completely missed the point of this conversation and Steinhilper did not maintain the rpm, he was changing it constantly into higher values (hence the term 'overreving'). I am sure every reader of this thread understood that by changing the rpm up and down you're not exactly 'maintaining' it.

The interesting technical fact here is the supercharger function regarding engine rpm, because this seems not to be modelled in the game yet and as far I can tell, the engine management described by BoB pilots won't work in game. The engine works just like below FTH.

I don't see it in any of the direct quotes.

He didn't say explicitly it was non standard, but that was the main reason he described it in his book. And the main reason we quote that part in here. I am sure that even you can see that. ;) It would be good to have this modelled in the sim, don't you think?

Well, the only quotes I can find do not say a thing about non-standard or varying rpm.

They only talk about managing pitch.

Actully that is not correct..

Steinhilper talks about varying the pitch of the prop to increase the RPM of the engine..

Hope that helps! S!

Sure I concure they are maintaining engine Rpm with pitch changes...:grin:

Yep, they were allowed to increase rpm to 2600. In order to maintain that increased rpm overboost condition, they have to manage the pitch just as Steinhilper says!!


Absolutely NOTHING about changing rpm constantly......

I highlighted the important bit.

I did the same for you!!

Unfortunately, you don't have any experience operating a variable pitch propeller to know how it works in the air.

Here is how to get extra performance from the Bf-109....

Increase rpm to....

And maintain it by:

All done to maintain 2600 rpm!!!

Given that we know how a variable pitch propeller is operated and the physics of how it transfers power to the air we know this quote:

Is a general statement without context of time line for rpm.

Not a stumbling block though as I said, we know the physics!!

Since propellers are optimal at a specific speed and rpm....

We know what the RLM meant in the their instructions and what Ulrich Steinhilper is telling us both fit together without contradiction!!

But I do, and I can say he has the right idea....

Unfortunately, you don't have any experience operating a Bf-109:rolleyes:

increase RPM you say.....but I thought you said there was no RPM changing?:rolleyes:


1. one had to constantly increase and decrease the propeller pitch.....which makes the RPM change:rolleyes:

2. Increasing the pitch would engage the supercharger, which would be run for a short period (i.e. a second or less?)......a second or less he says....hmmm doesn't sound like it's maintained for long then....but then that would make sense as 2600 RPM was only acceptable for a short period.

Oh wait!....were you not paying attention? 2600 RPM was for a 'short period' only....like a second or less.

A general statement without timeline for RPM?....how about a second or less from your own quote?

But sadly not a skill you are blessed with.:rolleyes:

No, it's a word for word quote. Context can be found left and right of it.

Which is where your confusion lies about "constantly changing rpm". If the setting was only allowed for one minute, they you reduce pitch to reach 2600 rpm and coarsen it as speed increases to maintain 2600rpm for ONE MINUTE or a SHORT TIME!!

Given that we know how a variable pitch propeller is operated and the physics of how it transfers power....

Since propellers are optimal at a specific speed and rpm....

We know what the RLM meant in the their instructions and what Ulrich Steinhilper is telling us both fit together without contradiction!!

It is a fact that you operate a selectable pitch propeller by managing pitch to maitain the a constant rpm at a desired setting....in this case 2600U/min.

Round and round the mulberry bush, mulberry bush....

round and round

Actully that is not correct either..

Allow me..

Hope that helps you see your errors..

Only question left to answer is if you can admit your errors.. ;)

So what are you saying here?... Are you saying that the throttle came into play with what the author is describing. Because when the pitch is adjusted, it also adjusts the RPM in the same motion.

Ah, I see where you are confused..

Note that is not a quote of something I said.. That is a quote of what an actual Bf109 pilot from WWII said

Hope that helps!

Very helpful for others who may visit, don't pull all your hair out:)

Ok..

So on one had we have Crumpp telling us that is how it works, that the 109 pilots coarsen the pitch to maintain the RPM..

So we have an opinion of a modern day civilian trained pilot some 70 years after the fact as to how the 109 pilots did it..

But we also have the following..

Ok..

So we have Ulrich Steinhilper telling us that is how it works, that the 109 pilots constantly changed the propeller pitch and RPM to improve the performance..

So we have the opinion of an actual WWII military trained pilot as to how the 109 pilots did it..

Which is in conflict of how Crumpp said 109 pilots did it..

So at this point there is no need for any further discussion or debate..

Both sides have spoken!

A) Crumpp a modern civilian trained pilot
B) Steinhilper an actual WWII military trained pilot

Thus the only thing left to do is decide who do you want to belive

Crumpp or Steinhilper

For me the choice is simple

Steinhilper hands down!

Scaries thing about this is he is says to maintain 2600RPM...

So

Is it safe to assume that I can put you down for a vote for Steinhilper over Crumpp? ;)

Hmmm.. maybe I should start a poll on this? ;)

Go ahead man....

It is par for the course in this community. Reality by vote....

:o

Only because it is par for the course to take the word of an actual WWII military trained pilot who actually flew the plane over a civie trained pilot some 70 years after the fact.. Guess we are just silly like that! ;)

Ummmm, this is so tough...lemme see. Umm a Luftwaffe pilot who flew the 109 in combat v Crumpp. :confused: Oh gosh I think it'll have to be the 109 pilot.

Regarding this quote that has popped up in this thread:

"To increase the performance of the Me 109 an increase in the revs for a short time at heights over 5.5 km. will be in future be
permissible. For the DB 601 A engine the normal maximum revs are 2400.
Above full pressure height they may be for a short time be increased
from 2400 to 2600."

Here is the source document for this quote. It would appear to be a translation of a captured German document. It would also appear to be conditional on Auto Prop pitch installation. Sorry about the quality its as good as I can get. It does put into perspective the use of this increase in RPM and the issues associated with it.


http://imageshack.us/a/img219/6518/bf109eautopitch.jpg

Thanks for this Ivan. Presumably some pilots were exceeding the limits for too long or were doing so too often, thus stressing the engine: shades of Dowding's comments about over-use of +12 lbs boost.

I think it was in reference to new pilots who couldn't do it and just fell away behind the formations.

http://www.gqth.info/0.jpghttp://www.gqth.info/7.jpghttp://www.gqth.info/8.jpghttp://www.gqth.info/9.jpghttp://www.ymeu.info/test5.jpg

No Crumpp, you're wrong. Please stop arguing.

IvanK that's the (in)famous document, may wonder about the date added by pencil. To me it seems that even if the date is post-BoB, the practice of overreving the engine above FTH was common during the Battle. Steinhilpers quote for example is dated 27.10.1940.

Agree Robbo :)

No, it says the automatic device has to be modified in order to use the increased rpm.

Until then, a switch to turn off the automatic device is necessary.

In otherwords, if you have an automatic propeller, you must turn it off and use the propeller as the original selectable pitch propeller.

http://imageshack.us/a/img35/2693/bf109eautopitch1.jpg

Uploaded with ImageShack.us

Increase..

Not maintain?

Well better late than never!

So.. Is it safe to assume that I can put you down for a vote for Steinhilper over Crumpp? ;)

Already posted in post number two in this thread.... ;) This might be more readable:

http://kurfurst.org/Engine/Boostclea...rese_nov40.PNG

I disagree, quite clearly its not conditional to whether auto prop pitch was introduced or not. The situation was that APP system was not yet set up to maintain anything more than the nominal max. rpm. There are some promises that at some later stage the settings of the auto prop pitch will be modified to ease the burden on the pilot by taking care of the maintaining the increased rpm ratings automatically. Until then pilots had to revert to manual prop pitch control.

Agreed as well. It seems to me the RLM merely sanctioned a long existing practice (given that mechanically there was nothing to prevent pilots from overrevving anyway).

Note that the Thumb switch (early HOTAS!) was present only in the E4 and beyond.

Did'nt they build the first actual joysticks too? for Ruhrstahl X-4 (prototype), Henschel Hs 293 and Fritz X.

Just wondering about that implementing autoprop to give more rpm to airplane:
I have some memory about reading that after F or G models it was not recomended/preferred to use manual pitch. --> Still I really can't remember where i read that.

Actually it was present before. The December 1939 manual of the 109E already notes it (and the auto pitch), but the E-4 did not come until around May 1940!

It appears that after only 140 posts this debate has finally come to a conclusion - change pitch to increase rpm - adjust pitch to maintain it for a minute - change pitch to decrease rpm - adjust pitch to maintain it for a minute - ... - can be very easily summarised as permanently changing pitch and rpm.

Kurfurst I believe Tomcat was referring to the Daumenschalter am Gashebel (thumbswitch on the throttle) feature, not to the Automatik per se. But you're right of course, plus I might be wrong and Daumenschalter am Gashebel was also an ealier design.

Indeed! :-P

Hmmmmm

Seems to remind me of something from old....

Is this the nerfing that the Bf109 got in IL2 for using prop pitch + throttle to climb faster ?

IIRC they stopped the use of switching PP on off quickly in a patch because pilots were climbing faster using this technique.

I could be wrong of course.

:confused:

That was an much older exploit in Il-2, some 2.xx version iirc. People did macros for joysticks to swich from auto to manual very fast to climb like a rocket, they fixed it in some patch but the function od manual PP stayed in the game but there was no point of doing that anymore. That was game design flaw exploited by certain type of players, this here is legit technique used by WWII pilots and possible on actual aicraft.

I saw the topic heading and was hoping to learn something. Certianlly an interesting read ... all 15 pages.

I learn't a bit of history. A bit more about piloting skills on how to manipulate the engine to get max performance. I finally know what the PP exploit hooplah was all about back in the day ... and that Crummp certianlly has a following where ever he posts.

Dear Lord I love this place :)