Showing posts with label wing pin handle. Show all posts
Showing posts with label wing pin handle. Show all posts

Sunday, March 12, 2017

Wing pin handles, safety pin

The spring operated safety pin to hold the wing pin handle in place needed lots of work. First the cut out in the wing skin is all wrong, so the safety pin will be too far fwd and too much inward to actually do anything.

The safety pin on both sides needs to be re-positioned, and because there already are holes and cut out in the skin, a skin doubler needs to be made. Found some scrap metal to make this.

Then I looked at the safety pin itself. It is spring operated to stay in the locked position by default. A closer look reveals that the spring is only held in place by an insanely tiny clip that easily can be removed by hand. If this clip is removed, the whole spring operation will fail, and the pin can simply slide to the side. It's function will be lost. I decided to make an extra safety mechanism to hold it in place. My old man has built RC planes for almost a century, so I called him to ask if he had some piano wire. He had lots of it, and I "borrowed" some 1 mm wire to make a a small wire with loops in each end. One end goes through a m4 bolt in place of the rivet, and the other end can be placed around the safety pin to physically hold it in place. A very simple fix that should do the trick if the original clip should fail (until it rusts away, and then I will make a new one).



Saturday, February 04, 2017

Upper left wing bolt

Drilled and reamed the upper left wing bolt. Perfect fit with the adjustable reamer.


Thinking about the wing pin handle, it is strange this isn't explained in the drawings. The pin is a perfect fit. It can only slide in and out There is no way it can rotate around the pin hole (in pitch direction). The wing pin handle rotates at the upper bolt. For a tight fit of bolts, this will of course not work, because the pin will be bent and will bite. This means the bolt holes must be enlarged. I made a drawing showing the different direction of the lower wing pin handle bolt and the wing pin bolt hole.


Sunday, January 29, 2017

Reaming wing bolt

When trying to mount the pin lock handle, I run into problems again. The pin just wouldn't enter, and I couldn't understand why. After lots of filing and adjusting, it suddenly became apparent why.


The holes didn't line up. It is obvious the upper hole in the handle should be made after the pin hole is made. Drilled up the hole to 5 mm from 3/16 (4.8 mm). I also widened the lower hole a bit. Then, finally I could operate the handle, and the pin.

Riveted on the rib and drilled and reamed the upper hole for the bolt. It looks like a really good fit. The wing cannot be moved a mm with the bolt and the pin in place. I will do the same for the other wing before drilling/reaming the aft pin hole. That will be the only leverage I have to do fine adjustments in case the wings are a bit twisted. With both of them on using the pin/bolt in the main spar, the aft hole can be adjusted 2 mm up or down. I have no idea how straight they are, I have found no way to measure them without mounting them on the fuselage. Most probable they are perfectly straight due to the laser cut holes from the factory. But then again there have been more than enough errors with these holes...





In addition to the adjustable reamer and the drill doctor, there is one additional tool that makes the whole thing much easier (have no idea what it is called in English):