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Phone ++64 (0)3 579 2033

Mobile ++64 (0)21 411 063

Fax++64 (0)3 579 3519

email tony@cams.net.nz

 

 

 

Gnome Rotary Engine Remanufacture

HISTORY REMADE

On Friday the 31st January 2014 at 3.35pm history was remade at the Omaka Airfield, Marlborough, New Zealand. A moment of great excitement and relief after some initial issues around timing were resolved – then the distinctive firing of one cylinder – a puff of smoke - a moment’s hesitation and then the dream of remanufacturing classic aircraft engines became a very loud reality for Tony Wytenburg and his team at CAMS Aero Engines as the Gnome burst into life for the first time. “There was no keeping it secret as the newly manufactured 100 hp Gnome CAMS 001 filled the air with the unmistakable smell of burned castor oil and the unique sound of a rotary engine on full song.” says Tony.

Sales and media enquiries:
Tony Wytenburg
tony@cams.net.nz
+64 3 579 2033

Gnome first run

January 2014 >>>

The first Gnome engine is nearing completion. Each passing day gets us closer to “getting smoke out of it” for the first time. Then there’s 20 hours of testing, complete strip down and reassembly before Gnome CAMS001 is delivered to its proud owner. To paraphrase Winston Churchill’s famous words, “that’s the end of the beginning”. Straightaway we are into production of CAMS002 and the other orders that we are assured by a number of prospects we can expect to receive as soon as 001 is shipped.

The engine is now mounted up on its test rig and we are working on building and assembling the test equipment.

We had the engine and prop on display at the recent Omaka Aviation Heritage Centre Flying Day and drew considerable attention. “The engine really is a piece of art.” was one of the comments we received on the day says CAMS owner Tony Wytenburg. “One recent visitor to our workshop commented ‘so this is where you put the magic in the metal’. We thought that was really expressive as a lot of the work that we do is more than just engineering – it has an element of art the way we ensure that corners are carefully radiused, surfaces properly finished, parts fit together perfectly.”

You can see from the photo that we have test fitted the prop onto the engine and at 9 feet (3m) diameter dwarfs the Gnome. The prop has recently had its test flight mounted on a Le Rhone engine aboard a Sopwith Pup. The prop greatly improved the Pup’s performance over its own prop so we are confident that it is close to right for the more powerful Gnome engine.

Gnome engine mounted

December 2013 >>>

Early in December 2013 we received the valves from a manufacturer in the UK. They have been manufactured from 21-4n stainless, induction hardened and have a stellite tip. Compared to the original valves these are manufactured in a vastly superior material and will last a very long time.

The tapered prop shaft that bolts onto the front of the engine was manufactured in HT steel.   We also manufactured a broach to finish machining the keyways/splines in the washer on the prop hub (See the “How we do it section).  We then machined the prop hub to suit.

Valve Set and Prop
Tony and Prop

We have also taken delivery of the custom made prop for testing the engine.  It is based on a Sopwith Pup prop and it represents a beautiful amalgam of craftsmanship and engineering. The engine’s speed is limited by the resistance provided by the prop so it is a critical part of the setup. The overall diameter and pitch has been increased compared to the Pup prop so that we can clip it if needed to adjust the maximum engine revs.

Cam cover open

The assembly of the engine is in its latter stages where we are progressively adding components and checking the clearances on each. The front cam cover was test fitted, the position of the cam lobe to the cam housing is critical. Once we were happy that this was correct we next looked at machining the holes for the cam timing gears.  We decided to make a cutaway front plate which would allow people to see how the cam timing worked. This is quite remarkable, especially when compared to modern day cam set ups. The cut away front plate also allowed us to check the position of the timing gear holes before we finished machining the front plate.

Late in December 2013 we have taken delivery of the forged aluminium pistons from the USA.  There has been a lot of technology advances in the manufacture of pistons over the years and we thought it wise to use the services of a specialist piston manufacturer to make a suitable piston to replace the original cast iron piston.

Piston and Gnome engine

A visit from Gavin Conroy and the semi assembled engine with its cutaway cam cover prompted an impromptu photo-shoot (above) and a short video clip of how the cam timing works.

October 2013

Timing Gears: The timing gears have had the teeth cut onto them and are now ready for assembly.
Cam Follower: Pins for the cam follower have been finished and new wire circlips made. This has allowed us to complete the cam follower assembly. The Cam sleeve and bush have been finished and now that we have the timing gears we have been able to test assemble the cams and timing gear onto the sleeve.

Timing gears and CAM follower

Rocker Arms: The rocker arms and all the rocker arm pivot pins and rollers have been finished. We have had new wire circlips made for the pins as well as new valve springs.

Rocker Arms complete

Valves and Pistons: One of the biggest challenges that we have faced is remanufacturing the valves. They are very large with a 12mm shaft and 60 mm head so adapting an off the shelf valve was not an option. After consultation with metallurgists we decided on a suitable material only to find bar stock of the size we required was not available ... but we could buy direct from the steel mill if we ordered 1000kgs!! We have gone with the best option (and safest) and the valves are being made in England by a valve manufacturer. They are forged in stainless steel and we expect them to arrive soon.
The pistons are high performance forged aluminium and are being custom made for us in the USA. They are also expected to arrive soon.

Propellor: The propeller for the Gnome engine is very important. It needs to be the correct diameter and pitch to control the rpm of the engine. We have enlisted Jeff Fox who is well known in New Zealand for his carving of propellers for WW1 aircraft. He has come up with a prop which he feels will suit our engine. He is making the prop so that if it needs to be tweaked once we have some performance figures from testing then there is enough material to be able to modify it. From this we will be able to accurately determine the correct specifications for the prop.

Crankshaafts

The cams and their mounting boss have been machined and the rear cover is now complete. Again this was machined from billet.

Cams and mounting boss
Master rod

<<< May 2013

The next major undertaking was to manufacture the master rod which apart from a little drilling and bushing of the small end is finished. Our remanufacture required a lot of machining as we had to machine from round stock.

Monday 8 April 2013 >>>

Lots of progress since the last update. The Classic Fighters Airshow 2013 at Omaka Airfield (where are are based) has come and gone. Visitors to the show were treated to a sight last seen in the early 1920s – a new Gnome Rotary engine. Enthusiasts got a good look and feel for what the finished engine will be like. It created quite a lot of excitement and more than a little interest in purchasing the last few in the initial production run. There are a lot of airframes around running radial engines that would look and sound great with the remanufactured rotary engine. The sound and performance of the rotary is entirely distinct from the radials commonly used because rotaries are not available. The Gnomes add to the authenticity of these classic aircraft.

The engine on display was not quite complete but none the less looking the part and able to be hand rotated on an original stand. It used the original rear casing and crankshaft for display purposes. We’ve since manufactured the new rear casing (see photo) and are about to begin work on the new crankshaft. 


More Cylinder Progress >>>
Monday 11 March 2013

More progress with the cylinder. The machining of the barrel and fins for the spark plug insert has been completed. The spark plug boss has been turned and then shaped to follow the inside contour of the combustion chamber. They are now off to have the boss welded to the cylinder.

<<< Cylinder Monday 18 February 2013

We thought that the completed crankcase was a thing of rare beauty but the first finned cylinder has got us really excited. We’ve completed the first set of “roughed out” cylinders and have now also completed the first of the delicate tasks of machining the cooling fins. Pretty cool – if you will excuse the pun!

 

Crankcase >>>
Thursday 14 February 2013

These photos show the process of producing the crankcase.

1. Raw steel billet (with the original crankcase half)

2. Crankcase machining completed with cylinder numbers exactly as per the original

3. Undercutting the cylinder mount

4. The first complete crankcase. We think that’s a thing of rare beauty!

Media and purchase enquiries please contact Tony Wytenburg phone ++64 3 579 2033 (We’re in New Zealand so we are roughly 12 hours ahead of US time, three hours ahead of Australian EST and a whole day ahead of Europe/UK – (check times here) or email tony@cams.net.nz.

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