Bob and David. Here's 246 airborne with 245...Two of only three RCN HUP-3's that Canada bought in the Spring of 1954. Piasecki only built 30 of the HUP-3's. So a pretty rare version. Note only 246 carries Labrador's sort of...kind of ..SeaHorse crest. It would seem from these photo's, that the R-975's were not that reliable. Not exactly sure when or where these photo's were taken. But can only have been a month or two into the voyage. BTW..Good notes about the cooling fan being charged over. The cooling fan has direct implications for AFV installations.

975-46
 

A couple of quick points about the helicopter - engine application.
In researching the helicopters two interesting ideas showed up. First, one source claims that the reason the -46 engine was used was because the US military had a surplus of these available. I am not sure what other significant application rthere was for -46 engines in the 1950s, though radial engines were used in other versions of helicopters.
There was also comments about -46 engines having problems, but little clarification as to what the problems may have been. While I am not a radial engine expert my inclination is to believe that radial engines ( like many aero engines) are high maintenance machines. I have heard many anecdotal stories about engine failure in this type of engine ( oil leaks, blown out spark plugs etc etc, but not just Continetal Wright) can anyone add more information about reliability, or problems not associated with ground machine applications?

Bob Phillips As you say...aircraft style engines are high maintenance machines. The case is thin aluminum castings with the steel cylinders bolted onto it. They are highly stressed and easy to break. For those installed in MV's, you have to keep the idle at 1000rpm to prevent main bearing failure due to lack of oil. They also break if they are over-revved. The allowable P&W R985 maximum rpm is only about 50 or a 100 rpm below what will hurt the engine. Oil in the lower cylinders ...aircraft or tank...has removed many a cylinder head..never mind entire cylinders. In answer to your question..aircraft type engines require far greater attention to handling. Many of the broken engines are the result of mishandling by the operator. Another hint...don't use the engine to slow your tank descending a hill. It can easily over-rev the engine and blow off a jug. According to the operators manual ...that's what the brakes are for. A lot cheaper to replace the brake pads... than replacing the engine.

Helicopter gearboxes, and by extension engines, are exposed to far greater torque than an aircraft engine and prop pulling air. When a helicopter is hovering, and especially close to the ground, there is a horrendous amount of resistance to moving the air, which can result in "over torquing" the drive train.
I am guessing that helicopter radials could suffer the same fate as tank radials when loads were too great.

Yes, exactly. Ground Hover torques the drive line to the max. In another question about the engine...In flight, it's sort-of level.

975-46
 

Related to Robs earlier post (37) I talked with Stew Robertson who was Bill Greggs mechanic about the two radial engined vehicles in the collection. While it was 30 years ago he recollected that the engine in the Sexton required a complete OH and so he tore it down and rebuilt it. This was a machine from England not one fron South Eastern Equip in Georgia. It was a long process especially trying to source parts from Toronto surplus yard, Levy Auto Parts. The Grizzly was running very roughly when it arrived from England and two cylinders, pistons, rods were replaced. Oil pressure was erratic but when repair work was completed it ran fine. This suggests damage from hydrostatic lock perhaps when attempting to start, but this is only a guess after 30 years.

Bob
Interesting info on the two engines. I get so much conjecture and hearsay on these two pieces I don't know what to believe.

Found this while doing some late night CAM reading.

Excellent, Ram tank material!

If anyone is wondering what CAM magazine is, see this thread:
http://www.mapleleafup.net/forums/sh...ad.php?t=28361

H.

975-46
 

Great poster Jordan!
I should send all interested readers, to an excellent WW2 era report on the R975 recently posted on the Sherman Site. It is the most detailed history I have ever read and I only discovered it a few weeks ago. Many interesting bits of information including;
- many failures due to overheatine, hence C4 styled cylinders
- significant issues with excess fuel during shutdown , therefore degassr shutoff valves
- over reving of engines (engine as brake) spells quick death to engine
- as C1 and C4 share 85% same parts many C1s converted to C4s during major overhauls
and much more!
BP

R975
 

In a previous post reference was made to the Bill Gregg collection now under the TLC of Rob L. There are some good photos of some of the major items including unrestored condition pics if you search up Bill Gregg photos at the Wellington County Museum and Archives.

R975
 

Just a couple of pictures to add to these older posts, an experimental flight with a helicopter using a 975-46 engine and a closer look at the shroud used on a -46 engine.

R975 rear main bearings
 

I have included some photos of the 975 rear main bearings. I am looking for some expertise from the forum readers if you can help. Both the C1 and C4 engine use very similar bearings- and while I have a large number of misc bearings the only difference I can see is the addition of the large slot/notch on some of these bearings. Can anyone verify whether C1 and C4 bearings ( which have different parts numbers in the manual) are in fact interchangable? You can clearly see a narrow keyway and the larger notch in the photos.

Attachment 111710 Attachment 111711 Attachment 111712

Just an update... The bearing with both slot and oval notch as shown is for a C1 engine. A bearing with only the slot is for a C4 engine.
A bearing for C1 will apparently fit and work in a C4 engine but a C4, lacking the oval notch, will not work in a C1 engine.

Slot
 

Maybe that large slot on the Wright 975 is an increase in the oil gallery size to get more moving through.

Peter S

HUP - but not of the CMP variant
 

Spotted last December: UH-25B (HUP-2) C/n 253, BuNo 130076. Location: Baris Business Park roadway roundabout in Rotterdam, The Netherlands. This aircraft was originally used by the US Navy and was later transferred to the French Navy. It is owned by Baris since 1973.

(I can post this here - a HUP is a HUP, eh? :D )

Attachment 111715

Because of the drive-by nature of my own photo I added some more NMPs for clarity.

Attachment 111716 Attachment 111717

R975 rear main bearings
 

I think you make a good point Peter, clearly the large channel around the bearing exterior is an oil channel ( you can see the small holes leading to the interior) so sticking a notch which presumably holds something must restrict or enhance oil flow?? don;t know but at some point will pull a bearing out of a battered crankcase to see.
Hanno, in my book a HUP is a HUP and more importantly in this day and age they have both survived the scrap man! Thanks for the post!
B.P.

R975 rear main bearings
 

To follow up my last post on rear main bearings I offer a photo of the -46 version, as I have done for most of the other main parts. Note the much heavier flange area. For those not familiar with workings of these engines, the bearing flange sits flush in the crankcase but the projecting threaded portion supports the camshaft.
Attachment 112238
On another topic, a couple of photos of nine mystery boxes, dug out of storage after almost 70 years...what could they be??
Attachment 112239
All export packed in waxed cheesecloth over heavy cardboard cartons...
very nice indeed!
Attachment 112240

R975
 

A beautiful sight for a Sherman enthusiast!

A beautiful sight, indeed! The military packing used back in the day was incredibly good quality.

We had a couple of visitors come by the museum from BAIV, a military restoration company in the Netherlands. When they saw our wrecked Sexton R975 on display, they said the cylinders are going for around 2000 euros each now! So good find.
Malcolm

R975
 

Malcolm, your appreciation is very much appreciated! Also a very unique smell as they were packed with thick heavy grease inside and outside.
I want to share a few pictures with you, reminiscent of those showing your beat up Sexton engine. This was a motor I tore apart, it looked great on the outside but not so great inside. You can see half a fractured link rod that was laying inside the motor, the piston was smashed to bits, I took out a couple of handfuls of aluminium chunks and look at the smashed up crankcase and the hole/slot cut right through the cylinder base as the rod came out! I suspect this was hydro static lock up induced, as it was a bottom cylinder right beside the oil sump. Must have been noisy for a few minutes as it disintegrated!
B.P.
Attachment 112291

Attachment 112292

Attachment 112293

That carnage looks horribly familiar!

Amazingly, our crankcase looked intact though dye penetrant may have shown some cracks.

And that bell-mouthing of the lower liners as the rods thrash around makes it very difficult to pull the cylinders.

Malcolm

R975
 

While this engine will provide a few spare parts, I see its future as a coffee table! Not much need to check cracks with this beauty, and, yes it is the worse and most smashed up radial I have ever encountered.
B.P.

Hi Rob
the sexton engine we rebuilt after Bill got it. It sat in the shop for almost a year before we got all the parts to finish it
It was not a hard job just took time . At the time I had and mechanic that worded for CP AIR help me with it
After the rebuild and break in of about 10 hrs we reinstalled it and put 400 or 500 gallons of fuel through it and it run flawless in the sesquicentennial parade in Kingston in I believe 1985
the biggest problem the engine had to be cranked by hand 52 revolutions of the crank handle before starting with the starter
That is what happened to the engines in the sexton and the grizzly in Shilo
oil compression or hydraulic locks and they scattered or bent a few rods
WHO NEEDS TO READ A MANUAL
lots of luck with the rebuild, Levy's are not around anymore
:cheers:

Thanks for your comments Stew.
In my earlier post (#73) I put up some pictures of the rear main bearing as used in the C1/C4 engine. I also floated the idea that even though the bearing is separately identified (by part number) for either C1 or C4 engine -perhaps they are/were interchangable. I have not yet pulled a bearing out of a crankcase to check, but I did find a sealed box labelled Continental Motors Corp, with intriguing and slightly contradictory labels, the outside indicating a C4 bearing the inside wrapping indicating a C1 bearing. See the photos.
A case of messed up packaging or strong indication about bearing interchanbability??
Attachment 112425

Attachment 112426

Wright engine manufacture
 

Check out this video of WW2 engine production in the Wright factory. Of particular interest is the detail shown in the manufacture of engine cylinders.
Amazing!


https://youtu.be/sBfFpcdyd5Q

1942 curtiss wright aircraft engine promotional film "wright builds for supremacy" 85
 

"A Cyclone 14-cylinder enigne contains over 8,000 separate parts, and more than 50,000 inspection operations are performed on the parts and the assembled engine before it leaves the plant."

Fascinating! The pinnacle of mechanical engineering and manufacturing.

R975 sparkplugs
 

Well while everyone is at home with lots of time to read and ponder, let me introduce the topic of sparkplugs in radial engines. Because most radials were designed as aircraft engines it is not surprising that in the early days tanks radials used aircraft sparkplugs. Aircraft plugs were shielded, had 18mm diameter
short reach (.5 inch) threads and had multiple electrodes ( usually 4). The premium manufacturer of aviation sparkplugs in the USA was the BG Corporation of New York.
These were not run of the mill disposable spark plugs. They were manufactured in two pieces and a well equipped shop had proper fixtures to adjust both the electrodes and the core. There are a number of BG plugs that were used in the 975 engine( and the 5 & 7 cylinder aircraft versions), 4B2S, 314-GS and 417-S. While the BG manual does not say they were suitable for the W670 Continental, it seems that in practical terms they were. (the finned 314-GS was intended for aircraft, not to build the economy version of a C4 !!)
By wars end the Champion 63-S plug was standard in the 975. It was a single electrode conventional plug but retained the shielded connection. See the photos below.
The 975-46 also used an aircraft type plug (AC) and it also used multiple electrodes. Perhaps this style was retained because they were used in helicopters. Note the longer threads on the -46 plug have been cut back to .5 inches so the threads don't foul with carbon (check out the Champion HO-14S beside it).
So anyone tell me why the change? Are multiple electrodes more prone to fouling and failure? Could it be about the cost of the part? All comments appreciated. There must have been vast quantities of the BG plugs made as they are much easier to find today than the Champion 63S.
Attachment 113189

Attachment 113190

Attachment 113191

Attachment 113192

Good stuff, Bob. I've always been interested in plug design and behaviour because it causes me so much grief in our fleet of vehicles!

From what I've read, including some good stuff on the NGK website, one reason for the multiple ground electrodes is to reduce electrode erosion because the spark is shared between 2, 3, or 4 electrodes. (Only one electrode sparks per firing stroke.) I see this design is still used in aviation plugs.

I suspect aviation engines have to deal with accelerated erosion because they normally run in the medium to high load range, especially under wartime conditions. These loads require spark voltages in the upper range, maybe 10kv to 20kv, hence more wear.

Maybe that's why the switch to single electrode plugs on tank engines as the load is much more variable so average spark voltage would be less, so less erosion. I wonder if they were hotter plugs too, as i believe fouling was a problem due to longer periods idling than these engines were designed for.

Malcolm

Just from a practical standpoint, how do you adjust the gap on a four electrode plug if you don't have the special tooling. I suspect that this cannot be done in the field therefore necessitating plug replacement.
Single electrode would have to be a better proposition for earthbound application and work just fine on millions of engines.

David

R975 sparkplugs
 

Thanks Malcolm and David for your thoughts.
I think maybe you have it- aircraft plugs are too difficult to service in the field? seems to make sense. Much of what I have read suggests radials have a bad habit of fouling plugs and need frequent changes of plugs. So this could be due to a too rich mixture at low speeds or too much oil working its way up to the plugs? I have pulled apart engines where the top rings are all seized- probably due to oil leakage toward the combustion chamber. Too much oil will certainly foul the plugs, an ongoing problem in radial type engines.