109 prop pitch (rpm) and the supercharger

[Robo.]

Originally Posted by Crumpp

It is all about maintaining optimum pitch and rpm.

As you coarsen the pitch to reacquire the rpm, you will notice an increase in performance.

That is how it works.

I understand how it works, no need for bold writing mate. My point was that it's not all about setting your engine for certain (optimal) rpm and keeping it that way - but especially at the altitudes, you would need to work with it constantly to get more speed. This is all relevant to the thread title which is about supercharger and rpm in 109s.

Originally Posted by Crumpp

In the quoted cases, they are setting the engine to a limited over boost and coarsening the pitch to maintain rpm.

To mainatin speed / performance. Not rpm... it's all explained in detail in the above quote...

[Crumpp]

Geez robo,

Quit being dense on this, I have explained how it works. What I am saying is what the pilots are doing.

that it's not all about setting your engine for certain (optimal) rpm and keeping it that way

Your point is wrong.

To mainatin speed / performance.

Right...by maintain rpm!!!!!

If you lived close by, I would take you and show you how it all works. My plane has a very accurate Engine Monitoring System.

Manifold pressure, rpm, and mixture are all interelated to produce a given performance.

[JtD]

Steinhilper explains how he's constantly changing pitch and rpm to improve speed performance. It would be interesting to know if the perceived increase in speed was placebo or not, but that doesn't change the method.

[Robo.]

Originally Posted by Crumpp

Geez robo,

Quit being dense on this, I have explained how it works. What I am saying is what the pilots are doing.

Thank you, I appreciate how you're trying prove you're right at all times, especially when you happen to be wrong.

Again - 'to maintain rpm' in my book means keeping it constant. That is possible and desirable for optimal performance of a 109 (even in CloD), but it is clearly not the case with the practice described in Steinhilper's quote, he was actually changing (changing is the word here) rpm up and down to maintain his speed = he would be slower without doing that = he would be in more danger with all those Spitfires around. I thought that quote would be interesting for virtual pilots in here and it is on topic with this thread (especially for supercharger part), but you obviously assumed that I don't know how things work because it is soo complicated. I am so glad to have you on this forums so thank you again for your kind offer.

[pstyle]

Originally Posted by Crumpp

Right...by maintain rpm!!!!!

Are you talking about prop rpm, or engine rpm?
Steinhilper makes it clear that engine RPM is changing with this technique.
I'm unclear about whether or not prop RPM fluctuates also.

[JtD]

Prop and engine are linked at a fixed gear ratio and if engine rpm changes, prop rpm changes as well. For the DB 601 on the 109E the ratio was 1:1.55, so if the engine is at 2400 rpm, the prop is at 1550 rpm.

[ACE-OF-ACES]

Originally Posted by JtD

Prop and engine are linked at a fixed gear ratio and if engine rpm changes, prop rpm changes as well. For the DB 601 on the 109E the ratio was 1:1.55, so if the engine is at 2400 rpm, the prop is at 1550 rpm.

Ok..

Originally Posted by pstyle

Steinhilper makes it clear that engine RPM is changing with this technique.

Ok..

Originally Posted by Crumpp

Geez robo,

Quit being dense on this, I have explained how it works. What I am saying is what the pilots are doing.

Your point is wrong.

Right...by maintain rpm!!!!!

Ok..

So we have

JtD pointing out that a change in engine RPM will result in an change in prop RPM

And we have a conflict between what Crumpp and Steinhilper are saying, i.e.

Steinhilper saying change the RPM
Crumpp saying maintain the RPM

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

Crumpp or Steinhilper

[pstyle]

Originally Posted by JtD

Prop and engine are linked at a fixed gear ratio and if engine rpm changes, prop rpm changes as well. For the DB 601 on the 109E the ratio was 1:1.55, so if the engine is at 2400 rpm, the prop is at 1550 rpm.

If this is the case (I don't know) the prop and engine RPM should be linked, so an increase in one results in an increase in the other.... in which case Crumpp's description appears to be contradictory.

Can we all specify exactly when we are referring to prop rpm, when we a re referring to engine rpm, and when we are referring to both?
That would sure help me understand.

[David198502]

the problem is the lack of information from the devs, whats working best in game.

[bongodriver]

surely the only RPM that can be refered to is prop RPM, I don't think there is an engine RPM gauge in most of these aircraft, engines can run happily at a range of RPM's but a prop must run within a certain range for efficiency, typically between 2,600 to 3,000, therefore it is more important to know what the prop is doing, certainly this is the case with modern aircraft...engine RPM is practically irrelevent and only fixed pitch non reduction geared aircraft you can assume engine and prop RPM are the same.

jtd is correct that prop and engine RPM are fixed in a ratio but a prop turning at 1500 RPM is not producing much thrust, so it would be more like prop RPM at 2400 and engine is at 3720 with that 1:1.55 ratio, I know were talking 1930/40 tech here but I'm pretty sure the typical aero engine of those days could cope with RPM's that high.