Warbird Information Exchange

To Whom It May Concern;

On behalf of the Aviation Museum of Warluis - Beauvais (France) I am attempting to trace the history and origin of an aircraft assembly in their collection, which we suspect is of a World War 2 era aircraft.
I realise this forum is to sell / buy parts but we are only interested in finding out about the history of the part, it is not for sale.

The assembly consists of a stem mounted fixed pitch propeller which drives a vacuum pump and a (suspected) hydraulic pump.

To only identification on the assembly can be found on the vacuum pump. The part identification tag is clearly readable and has the following information on it:

Vacuum Pump
Type B2-A Spec. No. 95-28135
Old Part No. 194-E
New Part No. 3P-194-E
Serial No. PE C110ZM or PE C1107M
Order No. W535ac 344993
Pesco Products Co. CLeveland Ohio

So far research on the internet resulted in finding the Service and Maintenance manual for this vacuum pump.
Would you please help us finding more information about the history and origin of this assembly, and which aircraft type it was fitted on.

Your help would be much appreciated.

Yours sincerely,

Gordon

Are there any numbers at all on the castings?

Sorry to say that there are no other numbers on the assembly.
The only numbers that can be found / read are on the vacuumpump

Unfortunately that vacuum pump is quite common.

Can you get some closer photos of the hydraulic pump? I wonder if it is a US model.

A glider might need a source of instrument vacuum, but typically a venturi is used. Not sure why a glider would need a hydraulic pump though.

Yes the vacuumpump is indeed a regularly found part, and even still in use!

I am not sure if the other part is a Hydraulic Pump, looking at the connection that were on it I suspect it is a "liquid" pump.
Research found that some aircraft had a proppeler driven fuel pump to provide positive flow to the engine during all fases /attitudes in flight. An early example of this is the Sopwith Camel.

I will try to get some more detailed photo's.
The search / hunt continues!

The Waco CG-13 had a hydraulic pump for raising the cockpit to open the cargo bay after landing. I'm not sure how this device could have effected the hydraulics after being on the ground unless it was charging some sort of fluid accumulator. As for controls, the vacuum pump could have operated flaps and instruments during flight- there was a good deal of experimentation with pneumatics to work flight controls before WWII but I don't know if any of that technology made it's way onto gliders. My guess on this would be glider or guided bomb technology. The nomenclature written is definitely WWII US AAF contract numbers.

_________________
REMEMBER THE SERGEANT PILOTS!

It looks like a early version of a ram air turbine. (RAT) on larger aircraft it provides electrical and hydraulic power which is limited.

The CG-13A (tri-cycle gear -- the CG-13 was tail dragger, not tricycle) like the CG-4A with "training gear" had hydraulic brakes. All other controls were cable controlled as on the CG-4A and CG-15A. The CG-13A hydraulic nose lifting device was a lever driven hydraulic pump which was not connected to the brake system.

Gliders (CG-4A, CG-13A and CG-15A that were fitted with the D-1 auto-pilot system) used a like or very similar propeller driven hydraulic pump. The D-1 was 100% hydraulic driven (no electrical or pneumatic power). On the CG-4A this propeller/pump for the D-1 was mounted on starboard side below the side windscreen outside of the fabric to right of co-pilot knees. Photo of the pump on CG-15A show it mounted on the port side, under the wing, on the vertical brace between the wing strut and the wing. I do not recall seeing a photo showing its mounting point on the CG-13A. Would have to check the installation manual next week.

These types of parts, similar to wheels, tires, brake systems, cables, pulleys, rocket assisted brakes and RATO, etc. were not specifically glider designed items. They were readily available manufactured parts or systems requisitioned for glider construction. If this part is from a glider, was found in Europe, and was used on the D-1 auto pilot, it would be rare excepting that the same pump was likely used more profusely on powered aircraft. If it was from a glider, you need to find the rest of the D-1 auto-pilot system. As mentioned previously, the glider instruments were venturi "powered".

_________________
Charles Day,
Silent Ones WWII Invasion Glider Test & Experiment CCAAF Wilmington Ohio

Dear sir,

Thank you very much for your explanation. It confirmed our suspicion that we had to find the answer to our quest in the group of glider aircraft of WW2.

What is still a mistery is the presence of the vacuum pump, as you wrote yourself a readily available part with extended use in aircraft.

It would be great to get some photographic evidence to go with the part on display, without wanting to take advantage of your kindness would you mind helping us in finding this? Sofar we have been unsuccesfull.`

Once again thank for much for your kind help and time.

Best regards,

Alf

The part to the lower right was identified as a C-47 tail strut!

My CG-4A contact (and his two mechanics) have not seen anything like this on the Waco glider they are restoring. It is nearly finished with the exception of the fabric covering. The instrument vacuum uses a venturi.

Could this be an apparatus for spraying some liquid out of an aircraft (pest control, defoliant, etc.)?

BDK,
There were two or so auto tow devices built and tested for the CG-4A and the D-1 auto-pilot. I do not know how many D-1 units were actually built and delivered to the Army but my guess is fewer then 200 compared with the almost 15,000 CG-4A, CG-13A and CG-15A gliders built. The only photos I have found showing these internal units or the externally mounted wind driven propeller on gliders were made in the US not in Europe.

Most glider pilots never saw an auto tow unit or a D-1 unit, let alone anyone who has been involved in rebuilding a CG-4A seeing one. The Silent Wings Museum, Lubbock, displays a CG-4A cockpit frame that contains the steel platform which held the hydraulic cylinder unit that connected to the control cables and was operated by the D-1 using the hydraulic pressure created by the wind driven pump. This platform was installed in he glider when the D-1 was installed. To my knowledge there were no D-1 factory installed in CG-4A gliders. They may have been installed in CG-13A by Ford and/or Northwestern. Otherwise, all of them were field installed. The D-1 and hydraulic cylinder unit for the SWM frame has never been seen. General knowledge of the D-1 is a bit like the knowledge of the papreg floors used in early 1945 CG-4A gliders. That is zero, general knowledge.

Some of the US glider pilots who did fly the D-1 did not like it because it did not control one axis. Fact is, it was designed to NOT control that axis. In 1946 the Brits installed and flight tested the D-1 in a Horsa. The report states that the tests showed that the D-1 could control the glider as well as if not better than the pilot. If the pictured unit can be proven to be from a glider, it likely then is the most rare CG-4A part known to exist.

_________________
Charles Day,
Silent Ones WWII Invasion Glider Test & Experiment CCAAF Wilmington Ohio