109 prop pitch (rpm) and the supercharger

[Osprey]

I'll be interested to re-read that part pstyle. I remember him talking about that, I think it was in reference to new pilots who couldn't do it and just fell away behind the formations. I seem to remember him mentioning that one chap was told to turn back and land because he fell away so far.

[pstyle]

Originally Posted by Osprey

I'll be interested to re-read that part pstyle. I remember him talking about that, I think it was in reference to new pilots who couldn't do it and just fell away behind the formations. I seem to remember him mentioning that one chap was told to turn back and land because he fell away so far.

Yes. You're right.
He does go into more detail about the technique in more than one place, not just with reference to that particular flight.

[pstyle]

Hi guys, as promised the direct quotes:

Of special importance was teachign them how to change the pitch of their propeller to get maximum pull from the engine at high altitude.
A flat pitch would allow the enginer to rev up to its maximum so that the super-charger would deliver the maximum vlume o air to the cylinders and
produce optimum power; chnaging to coarser pitch would have that enginer power converted into more pull and consequently speed our rate of climb.
It was vital they mastered this technique if they were to keep uo in a battl climb or at high altitude.

AND

... we began our climb almost immediately afdtetr take-off and he was constatly using the radio to ask us to slow down so that he could keep up.
It was obvious that he wasn't manipulating the pitch control with the skill of the more seasoned pilots to produce the same power as our mahcines...
Eventually, about half way accross the channel and at 4000m (13,000ft) Kühle told him to leave the fomration and retun home.

What I take from this:
1. The prop-pitch manipulation had direct impact on air-speed.
2. This technique was used BOTH at high altitude AND at low altitude in the climb, and had an effect in both cases.

I understand that this is not modelled in the game. Is that correct?

[TomcatViP]

Originally Posted by pstyle

Hi guys, as promised the direct quotes:

Of special importance was teachign them how to change the pitch of their propeller to get maximum pull from the engine at high altitude.
A flat pitch would allow the enginer to rev up to its maximum so that the super-charger would deliver the maximum vlume o air to the cylinders and
produce optimum power; chnaging to coarser pitch would have that enginer power converted into more pull and consequently speed our rate of climb.
It was vital they mastered this technique if they were to keep uo in a battl climb or at high altitude.

AND

... we began our climb almost immediately afdtetr take-off and he was constatly using the radio to ask us to slow down so that he could keep up.
It was obvious that he wasn't manipulating the pitch control with the skill of the more seasoned pilots to produce the same power as our mahcines...
Eventually, about half way accross the channel and at 4000m (13,000ft) Kühle told him to leave the fomration and retun home.

What I take from this:
1. The prop-pitch manipulation had direct impact on air-speed.
2. This technique was used BOTH at high altitude AND at low altitude in the climb, and had an effect in both cases.

I understand that this is not modelled in the game. Is that correct?

It's in the game. I rember giving on this forum the same advice to rev up the the SC.

So COD is "quite accurate" again

[Crumpp]

What he is talking about is doing the same a CSP does automatically, a controllable pitch propeller has to be done manually.

Fine Pitch to maximize rpm and coarsen the pitch to maintain rpm as speed increases.

If you don't lower the pitch, the propeller will begin to drive the engine and you will lose performance.

A given manifold pressure and rpm as listed in the POH will deliver the maximum performance for the condition flight listed. The pilot must maintain that rpm by controlling the pitch.

I have my pitch control set on a slider for the Bf-109 and adjust it constantly to maintain the desired rpm.

What I take from this:
1. The prop-pitch manipulation had direct impact on air-speed.
2. This technique was used BOTH at high altitude AND at low altitude in the climb, and had an effect in both cases.

You are making the right conclusions. The basics of operating an controllable pitch propeller are given above.

[Robo.]

Originally Posted by Crumpp

What he is talking about is doing the same a CSP does automatically, a controllable pitch propeller has to be done manually.

Fine Pitch to maximize rpm and coarsen the pitch to maintain rpm as speed increases.

If you don't lower the pitch, the propeller will begin to drive the engine and you will lose performance.

A given manifold pressure and rpm as listed in the POH will deliver the maximum performance for the condition flight listed. The pilot must maintain that rpm by controlling the pitch.

I have my pitch control set on a slider for the Bf-109 and adjust it constantly to maintain the desired rpm.

You are making the right conclusions. The basics of operating an controllable pitch propeller are given above.

There is another quote in that book, I copy & paste the part from bugtracker where we discussed increasing RPM of the DB 601A : http://www.il2bugtracker.com/issues/211

Quote from 'Spitfire on my tail' by U. Steinhilper, a Bf 109 pilot who has been shot down on 27.10.1940 - before the above document has been issued:

'We had to stay alert if we were to survive that day. Things had started to go wrong as we reached our operational height for the mission. When we flew at that height, the engine only just gave enough pull and we constatnly changed propeller pitch and RPM to improve performance. With a flat pitch we could increase the rpm of the engine and get more pressure from the supercharger. Then, by changing the piitch to a coarser setting, we could make up some speed. (... he then describes some issues with the prop pitch gears, probably from the moisture freezsing up at the altitude)... I decided to set the pitch at its flattest, this way I would be able to run the motor at high revs and gain the benefit from the supercharger. It would mean that the motor would have to be runing well above the maximum recommended RPM, but this had happened before in combat, without total dosaster.' (page 25 of the above book, describing how he got in trouble and got shot down / baled out on that very day)

It's not just about maniaining the optimap pitch and engine RPM...

[NZtyphoon]

Originally Posted by Robo.

Quote from 'Spitfire on my tail' by U. Steinhilper, a Bf 109 pilot who has been shot down on 27.10.1940

A question, and waaay OT - just how often did German pilots yell "Achtung Spitfire!!!" and did they ever yell "Spitfire!!" - I have long taken this to be an urban myth peddled by old British comics (a few years ago I flipped through an olde collection of Victor and Commando comics - every time a German pilot got bounced he yelled "ACHTUNG, SCHPITFUERER!!" or a variation thereof, then "AAARGH!!" as their 109 or 190 was torn apart...)

Did German pilots and aircrew actually use the British "Spitfire", or were they more likely to use the German equivalent Hitzkopf or Feuerkopf?. Just a question and pardon my ignorance.

[Christop55her]

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

[kohmelo]

Originally Posted by Steinhilper

Of special importance was teachign them how to change the pitch of their propeller to get maximum pull from the engine at high altitude.
A flat pitch would allow the enginer to rev up to its maximum so that the super-charger would deliver the maximum vlume o air to the cylinders and
produce optimum power; chnaging to coarser pitch would have that enginer power converted into more pull and consequently speed our rate of climb.
It was vital they mastered this technique if they were to keep uo in a battl climb or at high altitude.

Originally Posted by Technical Sheet Issued by the Quartermaster General Berlin 14th November 1940.

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
permissable. 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...

Originally Posted by Technical Sheet Issued by the Quartermaster General Berlin 14th November 1940.

...the excess revs can only be obtained by
means of the thumb switch after switching off the automatic device.
In doing this the danger of an additional impermissable increase in
the revs must be watched.

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

[Crumpp]

2400 to 2600...

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......