Exhaust pipes are built for the Snoopy´s ("Ressu" OH-XEA) engine

Suomeksi

We have constructed exhaust pipes to be fitted onto the Continental A 65 engine we acquired for the Snoopy (“Ressu” OH-XEA). This engine was damaged in an aviation accident, but it suits our purpose. We are refurbishing the engine on the outside to make it presentable for mounting onto Ressu's nose.

Photo: Esko Keskinen

The exhaust pipes are being built to match the Snoopy’s original Continental engine, based on photographs taken of the aircraft. The exhaust system on the Snoopy consisted of two straight pipes coming from each side of the engine’s two exhaust ports. At the end of the pipes was a barrel-shaped silencer with a diameter of 100 mm. Around the silencer, there was a separate shroud welded onto the surface of the exhaust pipe for preheating the intake air.

From the Continental engine we received, we managed to salvage the mounting flanges, which were still attached to the exhaust ports. Although the flanges were corroded and partly damaged, we decided to use them to connect the new exhaust pipes to the exhaust ports. The blanks for the new exhaust pipes were cut from 40 mm thin-walled furniture tubing. The flanges were cleaned of rust and then welded onto the ends of the exhaust pipe blanks.

Photo: Reijo Siirtola

On some parts of the flanges, the mounting surfaces were not completely even after the damage and welding. The end surface of the flanges was ground down so that the exhaust pipes could be joined at a right angle to the engine's exhaust ports. The flanges were ground by pressing the end of the pipe, locked at a right angle in a wooden frame, against the side of a grinding wheel.

Photo: Jouni Ripatti

Once the Continental A 65 engine had been blown clean and painted, we were able to start fitting the exhaust pipe blanks to the engine's exhaust ports and test-fitting the silencer pipes to be attached to the ends of the exhaust pipes. Two silencer pipes, each 100 mm in diameter and welded from thin sheet metal, were manufactured as an external job.

Attaching the round exhaust pipe blanks to the round silencers required, not only cutting them to the correct length, but also shaping the ends of the exhaust pipes to match the silencers. This was done using a “cutting jig” made from a 100 mm plastic pipe, the same size as the silencer. A hole was made in the plastic pipe, matching the size of the exhaust pipe, through which a slightly thinner pipe was inserted, allowing the exhaust pipe end to be slid on top of it inside of the plastic pipe.

With the help of this jig, it was possible to accurately draw onto the exhaust pipes the double-curved cut line, needed for welding the parts together. The pipes were then cut with an angle grinder in the fireproof workshop container at our Puusepäntie workshop. Then their ends were further ground to better fit the curved surface of the silencers, enabling them to be welded together. Now the exhaust pipes were ready to be welded to the silencer pipes.

In order to get an overall picture of what we were doing, the exhaust pipes on both sides were attached by their flanges to the engine’s exhaust ports. After this the barrel-shaped silencer pipes, still open at one end, were fastened with cargo straps against the ends of the exhaust pipes. In this way, for the first time, it was possible to visualise the complete assembly of the exhaust pipes and silencers for the Continental engine. Its appearance closely resembles the original exhaust system built for the Snoopy by the Hietanen brothers.

To ensure that the exhaust pipes would remain at the correct angle when welding them to the barrel-shaped surface of the silencer – a thick plywood support plate (jig) was made, carefully modelling the location of the exhaust ports on each side. The exhaust pipes were attached to the support plate, and it was further ensured that the exhaust pipes could not move in relation to each other. It was also checked that the exhaust pipes were at a right angle to the support plate.

Photos: Lassi Karivalo

Translation to English: Erja Reinikainen