Shackleton translation unit

[virgo]

I've been trying to explain how the Shackleton - and probably most other contra-rotating prop types - transmitted the forward propeller pitch change demands to the rear prop which was rotating in the opposite direction.

They say a picture is worth a thousand words.............has anyone got a decent diagram of the Propeller Translation Unit they could post ? Thanks.

[shack]

No but I can assure you that it is most unpleasant when one gives up the struggle just as you lift off at max,weight.

[ORAC]

The diagram in the US Patent in the top right of this web page (http://www.yonge-cvt.com/how-it-works-pitch.html)might give you what you want. Or the text of the page itself.

[virgo]

Thanks ORAC, but the Griffon used a mechanical system consiting of an enlarged ball-bearing sliding on the prop-shaft and connected to the front and rear props by push/pull rods............difficult to imagine but like so many good ideas, extremely simple.
(The device was designed by Sir James Martin of Martin-Baker Bang seats and was fitted to his MB5 experimental fighter. He was so devastated by the death of his partner, Valentine Baker when the MB5 crashed, he gave up aeroplane design and devoted his life's work to creating life-saving equipment to enable crews to abandon high-speed aircraft...........at which he was eminently successful !)

[MReyn24050]

The following is an extract from the Gatwick Aviation Museum Newsletter Summer 2006 (No 11) concerning a problem being experienced on Shackleton WR 982;
"Work to bring this Shackleton to a full running condition continues. For those who have been associated with Gatwick Aviation Museum for some while will know that we have suffered for many years with radiator problems. The basic problem is lack of coolant flow. Internally the radiators are almost fully blocked by crystallised glycol; many attempts have been made to flush out this material all with insignificant success. Now a new, more radical attempt to resolve the problems is under way. Number 3 engine radiators have been removed and have been sent to a During our regular swinging of the propellers a nasty scraping noise was heard coming from the front of the number 4 engine. We were hoping that it wasn't a problem with the propeller translation unit or the associated propeller mechanism."
They may have some APs on this system.
http://www.gatwick-aviation-museum.co.uk/news/11-summer2006/news11.htm

[shack]

As an ex-brat F2E and an Ex- Shack driver I really should remember.
The CSU was mounted on the rear prop and controlled it directly, then as Virgo says from that there were three "rack bolts" which each connected to it's own front blade and turned the blade so that the pitch of each front blade was the same as each rear one. A system that sounds a bit Heath Robinson but worked!!. Trouble came if you had a rack bolt failure, its connected prop would normally fine off to the feather position whilst the other five blades continued to obey the CSU much to the distress of the poor old Griffin that it was connected to and the airframe as well. It was however robust as in x'000s of hours in the old Grey Lady it only happened to me once.

[shack]

I have just been told by my smart ar*ed ex-copilot that I have got it wrong the CSU is on the front prop. Mates, don't you love 'em!!!

[OX-27]

Shack - I'm pretty sure that the CSU was bolted at the back/top of the engine and not the prop.
The Translation Unit (TU) was attached between the front & rear prop and was a right bu**er to replace.:8

[shack]

Is this what you wanted? Thanks to FMcC
http://i60.photobucket.com/albums/h21/Blunebottle/TranslationUnit.jpg

[virgo]

Thanks Shack..............the photo's fine if you KNOW how it works but not quite as good as a schematic to explain the mechanism.

The CSU......the bit that senses engine RPM........was mounted at the front of the engine and controlled the delivery of oil to the moving cylinder mounted in front of the front prop which it moved by means of helical gearing meshing with segments on each blade................absolutely bog-standard for hydromatic variable pitch props. The clever bit was transmitting the front prop movement to the rear one rotating in the opposite direction.

Thanks MReyn, I'll pop in to Vallance Byways next time I'm in the Gatwick area.