About the wheels of Caudron C.59 (CA-50)

The Finnish Aviation Museum and the Tuesday Club have a common subject for conservation; The Caudron C.59 advanced trainer, serial no CA-50, which was in service with The Finnish Air Force. The last flight of the type was in October 1929.

Brought from the Päijänne-Tavastia Aviation Museum in Vesivehmaa to Vantaa for conservation, the Caudron landing gear has genuine 1920’s wheels and tyres. The landing gear has already been taken apart, cleaned of rust and the surface finishing of the parts is under way by the Tuesday Club.

The CA-50 wheels are an odd pair, and the rims and spokes differ from each other. Otherwise the wheels and tyres are of the same size. One wheel turned out to be French with a NEUILLY-AVIATION-AERO 750-125 tyre. The markings on a very dilapidated tyre could only be read with the help of paper and a black grease pen. The tread of the NEUILLY-AVIATION-AERO tyre has been largely peeled off, exposing the canvas under it. The other was a British wheel. Its tyre is a PALMER CORD AERO TYPE 750x125, and it’s hardly in a better shape than the French one, which is probably an original Caudron wheel.

For some reason it had been mated with a British wheel. Is it possible that it had belonged to a Martinsyde F.4 Buzzard fighter, which was in service with The Air Force in the 1920’s, as the Caudron was.

Both the inner tyres have been at some point filled with polyurethane filler mass, squeezed in through the valve. This way the tyres have been made to resemble ”solid rubber” when the fuselage was standing on the landing gear on show in the Päijänne-Tavastia Aviation Museum hall.

The restoration of these wheels to their original condition was not possible without breaking them because of the polyurethane inside the tyres. So the question arose whether The Air Force Museum at Tikkakoski might have similar, but better 1920’s wheels to install on the CA-50. There was a suitable pair of wheels in Tikkakoski which fitted the Caudron’s axles, with Continental 750x125 AERO CORD tyres and clearly in a better shape.  Although they weren’t French. The Finnish Air Force Museum gave the wheels to be fitted to CA-50, so we fetched them from Tikkakoski to Vantaa.

The rims of the wheels with the Continental tyres were covered with a thick layer of rust, so the tyres had to come off. We didn’t take them to a tyre repair shop to be taken off the rims, instead we decided to take them off carefully in a manual tyre working bench in the garage of a Tuesday Club member.

Before starting to detach thy tyre, we warmed the tyre in hot water to make it softer.  After a while we took the wheel out of the bath and started the tyre work. First we pressed the edge of the tyre free from the inner edge of the rim where it had got stuck over the period of 90 years of storage. The parting of the tyre edge from the rim was done with a lever in the bench. With the aid of a metal plate in the lever it was possible to free the edge bit by bit and so free it from the rim.  In this way both edges of the tyre were freed from the inner edge of the rim.

It was time to separate the tyre. The wheel was lifted on bench and locked there with a metal peg and clasps attached to the wheel rims.  With the help of a tyre bar, we opened carefully an opening between the tyre and the wheel rim. Into this opening we pushed a metal rod with a down pointing ball-headed peg at the other end. Propping the metal rod against the metal peg in the middle of the bench and swivelled the ball-headed rod in the opening between the tyre and the rim counter-clockwise. This way the edge of the tyre was managed gradually on top of the rim. Simultaneously we applied lubricant on the edge of the tyre to facilitate the moving of the ball-headed rod between the tyre and the rim.

When the other edge of the tyre was on the rim the whole way, we pulled out the inner tube from the inside of the tyre. We noticed that the tube was a veritable patching wonder, because a large part of the tube was covered with patches. It was obvious that there was a shortage of tubes in the 1920’s, because the tube had been so diligently patched time after time.

We turned the wheel on the bench the other way round and in the method described earlier we lifted the other edge of the tyre on the rim with the ball-headed rod. Now we were able to pull the rim apart from the tyre.

The broad canvas band circling the rim was thoroughly rotten and had to be renewed. It also transpired that the inside of the rim was covered in thick rust. We detached the other tyre from the wheel rim as described before.

These Continental tyres seemed good enough to withhold the air pressure, together with new inner tubes. That being the case, they could be used when moving Caudron CA-50 around. Naturally this must be carefully looked into and tested. When being on show, trestles will be put under the landing gear axles in any case, so the aircraft won’t rest on its tyres.

The next phase will be removing the rust from the inner and outer sides of the rims before painting the rims. This will be done by immersing the rim for 24 hours in 33% phosphoric acid bath.

Photos: Lassi Karivalo

Translation: Matti Liuskallio.