Installing the control wires in the Snoopy's tail

Torstai 2.1.2025 - Tuesday Club member


Suomeksi

The experimental aircraft Snoopy, under restoration at The Tuesday Club, retains the wires from the rudder pedals to the rudder and tail wheel. Instead, the elevator wires had disappeared.

We examined the Snoopy’s fuselage to find out how the elevator wires had run. It transpired that the upper wire is attached to the top end of a rocking lever in the tail. Accordingly, the lower wire is attached to the lower end of the rocking lever. So, how to move the elevator? From the photos taken of the Snoopy we noticed a bar from the tail to the underside of the elevator. The other end of this metal bar has been attached to the lower end of the rocking lever, where there are holders both for the wire and the bar. As the wires tilt the rocking lever from side to side, the metal bar moves back and forth, making the elevator move up and down.

At the lower end of the control column the lower elevator wire runs through a pulley in the fuselage and on through a tube in the control column lower end winding around a pulley to the lower end of the control column. Accordingly, the elevator upper wire runs from the rocking lever through a pulley in the fuselage, straight to the lower end of the control column. This way the wire forms a connected wire loop that can be operated from the control column.

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Before we started to install the elevator wires, we had to lathe the two missing pulleys in the fuselage that guide the movement of the wires. The bolt holes in the pulley holders were drilled clean, after which the pulleys were installed. Now we could start threading the wires to place.

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The wires were tentatively fastened with loops with wire locks to the lower end of the control column and the rocking lever. After it was defined how tight the wires should be, the wire ends were equipped with metal rings or thimbles. The wire was tightened around the thimble and the end of the wire was locked at the stem of the thimble with two pressable wire locks made of aluminium. The thimble headed wires were finally threaded to the holder at the lower part of the control column and the locking loops attached to the rocker lever.

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After the elevator wires had been fitted, we constructed the metal rod out of 20 mm metal tube, to move the elevator, and fastened it to lower end of the rocker lever. We further checked the working of the rod by attaching the horizontal stabilizer and elevator to the fuselage of the Snoopy. When we fastened the other end of the rod to the bracket on the lower surface of the elevator, it moved as planned, when pulling and pushing the control column.

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A wire connects the rudder pedals both to the rudder and the tail wheel. The wire running towards the tail, forks halfway of the fuselage to wires going to the rudder and the tailwheel. The tailwheel turns simultaneously, when the rudder is turned by the pedals.

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We fastened first the right- and left-hand side wire ends to the pedals. After that we attached the ends of the rudder wires, which forked halfway of the fuselage, to the brackets on the lower left-hand and right hand-side corners of the rudder. At the same time we noticed that in front of the rudder, there had been pulleys guiding the wires in the fuselage. All that was left was the holder for the pulleys.

The missing pulleys were lathed and attached in place. Thus the rudder wires had been installed.

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It was time to install the tailwheel wires. The left-hand side wire had been linked to the tailwheel by a coiled spring. The right-hand side original wire lacked the coiled spring. When we thought about the problem, we found out that both the wires should have the coiled spring for the rudder to function properly.

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We studied photos of the Snoopy. It transpired from them that both the rudder wires did have a coiled spring. Why it lacked from the right-hand wire, will remain a mystery.

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We carried on pondering. If the tailwheel wires have coiled springs, they must have counter springs in the pedals. This way the wires between the pedals and the rudder could remain tight and the rudder movements transit to the rudder and tailwheel. Small metal rings were found in the fuselage and rudder pedals. So we bought suitable coiled springs and installed them to the rudder pedals.

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We also bought coiled springs for both the tailwheel wires.  So we decided to renew the left-hand side tailwheel coiled spring, in order for both springs to be identical. Before installing the tailwheel wires, we had cleaned the pulleys for the tailwheel wires to be fastened to the tailwheel coiled spring.

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At first the coiled springs on both sides were fastened to the brackets in the tailwheel. After this both the wires were attached to the coiled spring with a ring made to the end of the wire. The ring was locked with two wire locks that were pressed around the wire. We still installed, as had been in the original, a backup wire between the brackets and the ends of the wires. The backup wire was threaded through the coil spring. The wire ensures the function of the tailwheel if the coiled spring breaks loose or breaks. We added a turnbuckle to the left-hand side wire of the tailwheel to adjust the tightness.

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Thus we had installed to working order all the Snoopy’s control wires in the tail section.
A different story will be the fitting of the aileron wires in the wings.

Photos by Lassi Karivalo.

Translation to English by Matti Liuskallio.

Avainsanat: aviation history, restoration, Tuesday Club, Hietanen HEA-23b, OH-XEA, "Ressu"