Spitfire IIa prop pitch

[Blackdog_kt]

Originally Posted by Kurfürst

Yup, my understanding is that effectively the 109 Automatik is just the manifold pressure throttle linked to certain RPM, it keeps the

It wasn't fixed-pitch-to-certain-MAP since if you think about it - if *pitch* would be fixed, rpm would increase/decrease all the time as speed - and load on the propeller blades - would decrease/increase.

In essence its just a single lever CSP where you can set the rpm/map correctly quickly and convinient. You did not have to mind much how to set up the engine.

On Allied planes with CSP, you set the desired RPM and MAP seperately, and the system would keep the RPM constant, by adjusting the pitch as needed. You still had to set the optimal RPM/MAP combination manually, by using two seperate levers, and there was a bit of a backside, since you had to do this in correct order , IIRC/AFAIK for example when increasing power, first RPM needed to be increased with the RPM lever, then boost, otherwise you would run the engine at low rpm / high boost which would stress the engine. The downside was that it required more attention from the pilot, and a bit of extra work.*

This was not modelled correctly in old Il2, and I as I recall it still isn't in COD.

* later it seems that a simplistic mechanical "system" was introduced, according to later Spitfire manuals for example that mention interconnected control. This however I believe was fitted only the some later Mark batches - impossible to tell which ones and how many - and not all planes, and the system was merely a metal rod that ensured that if MAP was increased, the MAP lever grabbed the RPM lever and pushed it forward, too. But unlike on the 109, it did not give optimal rpm/map combinations on most of the lever movement range, it just enabled the pilot firewall the throttle quickly and push both rpm/map the maximum regime.

Yes, you' right. I guess it tied RPM values to MAP values (which means changing pitch to maintain RPM). Well, that's what i get for typing posts about technical things late at night

Also, very interesting what Crumpp has to say. I read that link a while ago and always had the impression those props were only electric and the auto-system just changed pitch to maintain the MAP-RPM relations specified. So they were actually electric in manual mode and hydraylic in auto mode? Very interesting system.

[Crumpp]

I think the confusion comes from the fact the propeller is electric. An electric motor is what changes the blade pitch.

The motor is operated by a hydraulic switch in normal operations and functions as a CSP. The hydraulic's reads the engine rpm and converts it hydraulic pressure with a regulator. That pressure then operates the electric motor to adjust the blade pitch to maintain the calibrated rpm. This way, both engine and propeller can be operated with a single lever in normal operations.

In an emergency, the pilot can manually operate the electric motor to change the blade pitch to maintain rpm or feather the propeller should he lose hydraulic pressure.

[VO101_Tom]

Originally Posted by Crumpp

I think the confusion comes from the fact the propeller is electric. An electric motor is what changes the blade pitch.
...

Hi.
The 109 had no hydraulic prop pitch, just a simple electric rpm regulator and motor. That was the point, is that hydraulic failure does not cause an failure of PP. Fw-190 has elektro-hydraulic combined system. I think this verstellgerät, which showed that belongs to 190's BMW engine.

[TomcatViP]

Thx Tom

It seems I mixed both the 109 & 190 system.

[Crumpp]

The 109 had no hydraulic prop pitch, just a simple electric rpm regulator and motor.

I am confused, are you thinking what I told you was wrong? It is not. The FW-190 and the Bf-109 have the same basic system. An electric propeller controlled by a hydraulic switch. The picture I posted is the BMW 801's system which basically combines many of the separate components of the 109 system into a single unit.

The motor is operated by a hydraulic switch in normal operations and functions as a CSP. The hydraulic's reads the engine rpm and converts it hydraulic pressure with a regulator. That pressure then operates the electric motor to adjust the blade pitch to maintain the calibrated rpm. This way, both engine and propeller can be operated with a single lever in normal operations.

That is the function of the Drehzahlregular. If you look at the diagram, you can see where it is mounted to the engine pad and connects with a splined shaft. It requires an oil filter because the engines oil circulates through it and it reads the pressure to meter the amount of current to control propeller rpm, ie...blade pitch.

It seems I mixed both the 109 & 190 system.

No you haven't mixed them up. They work exactly the same. The propellers are ELECTRIC but are controlled by a hydraulic switch. I think there is confustion over the hydraulic switch. That hydraulic switch is an ELECTRICAL Switch that meters electrical energy based on hydraulic pressure. It changes the electrical current going to the propeller based on the engines oil pressure.

[VO101_Tom]

Originally Posted by Crumpp

I am confused, are you thinking what I told you was wrong? It is not. The FW-190 and the Bf-109 have the same basic system. An electric propeller controlled by a hydraulic switch. The picture I posted is the BMW 801's system which basically combines many of the separate components of the 109 system into a single unit.

The basic principles can be the same, can not argue with this, but the BMW Commadogerät is a bit different device than the 109 VDM auto PP. The only hydraulic equipment in the 109 the landing gear.

190's Commandogerät:

[Crumpp]

The basic principles can be the same, can not argue with this, but the BMW Commadogerät is a bit different device than the 109 VDM auto PP. The only hydraulic equipment in the 109 the landing gear.

190's Commandogerät:

We are not talking about the Kommandogerät, we are discussing VDM hydraulic electric propellers. The KG is a completely seperate device and no, it is not the same as the system found on the Bf-109 and nobody ever said it was either. Both the FW-190 AND the Bf-109 use the same type of VDM hydraulic electric propeller. That is a fact. I am not telling you this out of a passing interest. I happen to know what I am talking about because I deal with the real thing.

Crumpp says:
The propellers are ELECTRIC but are controlled by a hydraulic switch. I think there is confusion over the hydraulic switch. That hydraulic switch is an ELECTRICAL Switch that meters electrical energy based on hydraulic pressure. It changes the electrical current going to the propeller based on the engines oil pressure.

Crumpp says:
That is the function of the Drehzahlregular. If you look at the diagram, you can see where it is mounted to the engine pad and connects with a splined shaft. It requires an oil filter because the engines oil circulates through it and it reads the pressure to meter the amount of current to control propeller rpm, ie...blade pitch.

Do you know who I work for?

http://www.white1foundation.org/

Here is OUR Kommandogerät....

http://www.white1foundation.org/part...andogerat1.jpg

YES IT WORKS..

We are also the North American distributor for Motobende. Do you know who they are?? He specializes in Diamler Benz inverted V's. Schwarze-man works for Dirk.

The seven-cylinder Bramo Siemens SH-14 radial engine was stripped,
overhauled, and rebuilt by Dirk Bende of Motobende Gmbh. This company,
based at Köningswinter-Sassenberg near Bonn, specializes in the overhaul of
German-built World War II-era engines and the remanufacturing of engine parts.

http://quax-flieger.de/sites/default...geSept2011.pdf