Propeller detail for the Alfa-Romeo RA1000 RC41 "Monsone"

[Engineman]

Hi all!

I am gently examining the details of the Italian propellers used on the Macchi C.200, C.202 and also the C.205.
So far, it is not a simple task, as there seems to be relatively little detail, although my task is not easy due to my lack of Italian language skill!
Very simply, the propellers used are, when rarely mentioned, referred to as the "Piaggio P.1001" which seems to be an Italian design that incorporates some common features with the German VDM types, although with considerable differences.
The information trail starts with the C.200 and this is slightly more fruitful. With the radial FIAT engine and no spinner, it can be seen that the prop Hub assembly and the operating pitch-change gear mechanism behind have some similarity to the VDM, but they are different. This "P.1001" propeller system seems to be covered in a Piaggio P.1001 manual. However, the description of the operating system is complicated and does not match the cockpit equipment to be seen in the aircraft, C.200, C.202 or C.205 as far as I can tell!
Unfortunately, pictures of the propeller hubs and prop equipment of the C.202 and C.205 seem to be very rare and definitive detail of the propeller type on the later aircraft is elusive.
So, does anyone have some better detail on these propellers?
To start with I can show a little info that I have defined.
The Italian propellers on the Alfa Romeo RA 1000 RC.41 licence built DB 601A engine were fitted onto an extended stub shaft with x36 fine splines, rather than the German DB 601A engine that used a radial splined coupling on the prop shaft extension with x16 coarse splines. The plot thickens, when I look at the Piaggio P.1001 prop manual and that seems to show x16 coarse splines in the Hub.

DB 601A

Alfa Romeo RA 1000 "Monsone". Pic from Milan Museum. Note the fine splines on the extended stub shaft.

A screen grab of the Piaggio P.1001 Prop hub, visible in the centre is the coarse spline shaft feature.


Cheers

Eng

 

[Engineman]

Hi All!

Well, I have achieved some progress! I have found several manuals that can be viewed on this site! The member who posted them has not been logged on the site since 2014 and only has 7 posts! However, he posted several Macchi manuals! These are a good mixture that cover the C200, C202 and C205. To find them, search member Alexxtres and look on his posts. The downloads work today for me, they are great. The only issue is that only the first will download as saved file, the others seem to be locked so I cannot print them.
Anyway, they have some great information! Thanks Alexxtres!

Looking through these downloads, I have found primary detail on the propeller types for the Macchi C200, C202 and C205. The original manuals show the following written details:

C 200 . The first 24 aircraft were fitted with a tipo "FIAT" prop. After that, this type was fitted with the Piaggio tipo P.1001 propeller. This version is described as being able to hold an rpm when selected on an unusual selector/indicator instrument that was fitted on the LHS of the cockpit. The indiicator instrument did include a blade pitch reading scale, but the instructions say that it was inaccurate (translation "crazy"!).
At the moment, I understand this system could HOLD a set pitch OR maintain an rpm (constant speed) when selected on the selector/indicator. I also think it could select minimum pitch and step down to that in stages by selecting with timed adjustments or 2 or 3 seconds at a time.

C 202 . This is the first with the DB 601 V12 engine. The partslist/instructions list a different propeller/control, the Piaggio tipo P 1001A propeller. This is a different unit without the indicator/selector. Instead it seems to have simple selections between automatic constant speed or adjustable fixed pitch.

C 205 . This is with the DB 605. The manual/partslist shows these aircraft to have been fitted with another type of propeller, the Piaggio tipo P 2001. This is similar looking to the earlier
ones, but looks a bit stronger/chunkier. Again no indicator.


So, some great detail, if you are interested, have a look at those manuals!
At the moment I am having difficulty with the translation of the operation of the units, the translations seem to be very poor. However, I know more than I did this morning!

Hope that is interesting.

Eng

 

[MiTasol]

A great project and I wish you well with it.

It is a pity that covid killed the avia.it web site as that had hundreds of Italian manuals. Maybe try the wayback machine to see if any were captured.

 

[Engineman]

I thought you all might like a screenshot of the Propeller controller/indicator/selector that is listed on the description of the Macchi C.200 Saetta using the Piaggio P.1001 Propeller and control units. This drawing shows two types of the unit, the one on the left was used on the C.200.

The 0-30 numbered scale is, I believe, indicating the prop pitch. This function seems to be discounted for use, because of inaccuracy, in the description. However, the 0-30 range shown is very limited, unless it shows a range above the Fine pitch stop or, if the scale is not simple degrees of blade pitch.
The rotary selector knob is used to select the mode, in conjunction with the two "Max" and "Norm" pushbuttons (with indicator lights).
The rotary selector is headed, "Commanded Pitch" and has four positions, 0, MIN (Finer pitch), Arresto (Hold) and Max (Coarser pitch).
The lower two pushbuttons are RPM range selectors. You are either in the Norm rpm range, or the Max rpm range.
This is quite a busy instrument/selector. The functionality is complicated and I will try to decipher it for us later. The descriptions of function are very confusing when translated!
At the moment, I think for adjustable manual pitch control, you have the rotary selector at ARRESTO with NORM selected. Then, to coarsen the Pitch you select the rotary selector to MAX for a few seconds then back to ARRESTO. Or, to fine-off the Pitch you select MIN for a few seconds then back to ARRESTO to hold the Pitch.


Cheers

Eng

 

[Engineman]

Hi everyone,

Not much progress today. I am having difficulty with the poor translation tool that I have (phone photo translate). The basic manual prop pitch control seems to be as I described previously, and the "0" lever position seems to just be "Off", in effect. The other selections of more automated operation translate into unreadable nonsense.
I am hoping that someone has either a good understanding of technical Italian or, a good text translation tool and can make some better translation for this?
So, sticking with the C.200 Seatta for now, I have copied the manual cover and 11 other pages that describe the operation of the Piaggio P.1001 propeller system. Included is the illustration of the control/selector instrument in simplified form and a table of selections to use the system. From the table, I have so far deduced the OFF position (yes, WOW!) and the manual adjustable pitch mode. That leaves what should be cruising and max performance constant speed modes.
TBH, even the Italian titles for these modes seem complicated.
So, here are the cleanest copies of these pages. If anyone is able to OCR these I would be very grateful and/or if anyone feels able to offer any insight by reading them, please post your interpretation.

Cheers

Eng