Stirling bit to be identified

Hi Walter

We’ve been fortunate in being able to acquire a copy of the Parts Catalogue for the Stirling. I’ll have a look through it in the next few days. To be honest, It’s not a part number sequence I’ve seen on the aircraft but, I’ll have a look to see what I can find

regards

John

Hi all,

Time to dig up this oldie as my contact has been able to clean up and dismantle the piece and found some stamped numbers on one of the
cogs : SFB644/6R9046

[ATTACH=CONFIG]252060[/ATTACH]

Would that number help us to pin it down to the Stirling?

Any thoughts appreciated.

Cheers,
Walter

Thank you Elliott. Guess we’ll have to keep it at that for now. Have been peering at drawings in several AP’s and various photos of Hercules power eggs but the rear of those engines is so cluttered with various bits and pieces it is hard to identify anything!

Cheers,
Walter

It’s a sprocket for the Hercules engine controls Walter, but i’m afraid I can’t be more specific than that.

Hi James & all,

James, you do have a keen eye ;)! Did some more searching myself and am quite sure we can rule out the cooling gill bit theory!

First a link to a Bristol add in a prewar issue of Flight (can’t seem to upload PDF docs) : https://www.flightglobal.com/FlightPDFArchive/1937/1937%20-%202930.PDF

The photo of the cooling gill ring is clear enough to show the mechanism matches that in James’ AP page.

I then found detailed pics of the gill operating thingies and the sprocket from a Bolingbroke on www.bristolaero.org :

[ATTACH=CONFIG]241292[/ATTACH]

Photos reproduced only for research purposes of course.

Again a perfect match to James’ AP page and the photo of the sprocket shows us it has an internal thread that converts the rotational movement of the sprocket into a fore and aft movement of the gill actuator (hope I’m making myself clear!). The Stirling bit we’re discussing has the forked end solidly connected to the sprocket so clearly has to be something else… the question is what.

Cheers,

Walter

Hi Walter

Found another (out-of-focus) picture of the Gill mechanism from the Hercules XI AP – There is no indication of a ‘double’ and only one chain.

If it is a double it doesn’t look like it would come from a Hercules XI engine so possibly the parts are not from a Stirling? Could be a later engine but not sure that they would change the Gill design.

Why is it that of all the pics you take only the ones you need are out of focus!?

Cheers
James

As for that double ended item, we’ll I’m afraid it’s not just two single ones jammed together, see below new pics please :

Hi Walter

How far out was I though? It was after all something that was actually in two part separate parts – and so the pic was misleading. 😎

I’m still a little skeptical, but I would think that looking at the way they could be used might shed some light

They could be male and female ‘single’ items with the same thread and diameter, perhaps they are ‘handed’ for different chain rotations for port and starboard wings?

Imagine the chains around the two cogs – they could not be arranged so that the two parts would come ‘unscrewed, there might be a clue in that.

Another way of looking at it is to work out what the internal mechanism would have to be for a double and see if it is actually possible for something to be assembled that would ‘work’. Again all just musing.

Hopefully someone will come up with the answer!

James

Hello all and thank you for your input!

Alan, your mentioning Blenheims made me check the Blenheim AP which yielded this :

[ATTACH=CONFIG]241127[/ATTACH]

The sprocket in “Y” would appear to be similar to the piece we’re trying to ID and James’s page out of the Stirling AP would again confirm same.

As for that double ended item, we’ll I’m afraid it’s not just two single ones jammed together, see below new pics please :

[ATTACH=CONFIG]241128[/ATTACH][ATTACH=CONFIG]241129[/ATTACH]

As you can see the two neatly screw together so definitely appear to have been meant to be assembled that way. Part of the cowling gill operation sounded very plausible but I can’t see a double sprocket put to use in that…

More pointers, ideas and comments more than welcome :).

Cheers,
Walter

Hi All

The items on the photo seem to be misleading. I be happier if the double ended item is in fact two single ones stuck or jammed together, the bearings might still be inside! If they are in fact a double it is hard to see what they might be pushing apart, whatever it might have been would have had to have symmetry, and operate about, the chain drive centre line or the chain would have moved out of line that just makes it less likely to be a double I would have thought.

The single cog looks like it is from a broken item, be nice to see if there is in fact a piston inside each that could extend. You can see where the piston was in the ’empty’ one.

I guess that this item was bought-in and so wouldn’t have had a x29xxxxx number or be in AP 1660.

I had to track down the operation of the Gills to work out how they did this:

https://www.youtube.com/watch?v=Z2HD_tB2ys8

(Shameless plug!)

James

That would explain why they seem to turn up at crash sites where the aircraft was Bristol powered and don’t seem particularly rare, you learn something new everyday.

As a guess, I’d say control linkage for the engine cooling gills?

For Info.

James

As a guess, I’d say control linkage for the engine cooling gills?

Hi Walter

My first thought is that it’s part of the trim control, as you say AP1660 doesn’t give out much in the way of info. A pity that there’s no other identifying marks as I’ve now collated nearly 6000 part nos and descriptions from various sources and unfortunately there’s no comprehensive Vol 3 to help us out. If it needs a good home, I can think of one 😀

regards

John

I am not sure of the exact purpose but that part is from one of the engines, I have seen numerous single cog versions of the same part on Wellingtons and Blenheims.