My Wooden Airplane
Skip Navigation Links.

7/6/2011 - 7/19/2011

Shock Struts

These were a little bit tricky. First, I had to find the right springs. Aircraft Spruce sells a Die Spring set that turned out to be too stiff. However, I found the original manufacturer of those springs, and it turns out they also make lighter springs, so I ordered a couple sets. The yellow ones below are from Aircraft Spruce. The others are from Anchor Danly. I think the blue ones might be a little too light, so I'm going to try the red ones first. They are part # 9-3224-26.

Next, I had to cut the slot in the upper piece for the bolt to slide in. We first tried to do it on a milling machine, but while one slot came out perfectly, the other side was very wavy. Not good. So, I had to make a new upper piece, and decided to cut the slots "manually". I drilled a couple of holes to mark the ends of the slot, then used a Dremel tool and cut-off wheel to cut out the rest of the slot. Finally, I used a series of files to smooth everything out. While not quite perfect, it turned out to be usable. The second strut came out much better. The trick, I found, was to drill smaller holes than required at first. In the picture below, the top strut is fully assembled, while the bottom one shows all the pieces.

Here they are, installed. The plane is now resting on its own gear!

Here is a close-up of how the struts attach to the axles.

And here is a close-up of how they attach to the fuselage. As mentioned during the construction of the Gear Legs, there was a discrepancy in what hardware to use. The plans say to use AN5 bolts, but the bushings in the ends of the struts are made from 3/8 x .058 tubing, which will only allow the use of AN4 bolts. A call to the designer revealed that the preferred solution would have been to use larger (7/16 x .058) bushings to accomodate the larger hardware, which would also require the use of larger (9/16 x .058) tubing ends. But since my struts were already welded, an acceptable alternative was to use NAS6204 hardware. Those are the bolts with the large dimples in the heads.

Total Time: 23.5 hrs.