Right Flap Hinge Retention

January 22, 2012

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Alright, with all the excitement of getting the flap on the wing, I decided that I might as well continue with the flap hinge.

Currently, the flap hinge pin hangs out 2 feet on the inboard side of the wing, so let’s get that thing cut down to a reasonable size.

I’m following the method of cutting some hinge eyelets from the middle of the wing/flap and attaching two halves of the hinge pin in the middle. At the end of the last session, I had marked the middle eyelets.

Here's me unbending the two middle eyelst on the wing so I can cut them off.

Where's my file?

Can’t find it. I’ll have to clean those up later.

I cut the hinge pin in half and 90° bent them.

OMG, more toes!

With some careful measuring, cutting, and bending, I got one of the halves right where I wanted it.

Like a glove.

Then matched the other side to that.

Like some other builder’s, I’m going to use the hinge eyelet method of securing the hinge pins.

During this whole process, I kept thinking how easy it would be to drill a single hole in the flap brace and just safety-wire these two hinge pins in, but I couldn’t bring myself to not finish with the original plan. More later.

Two of my hinge eyelets from scrap.

The hardware I’m going to use.

I'm using the 2-lug, MS2169106 (I think that's right) and the AN507-6R6 screws.

There's a nutplate under there.

Rivets set.

The two eyelets are not countersunk or dimpled. I'll eventually need to replace this countersunk head screw with a panhead.

After getting the hinge pins secure, I checked out the outside.

Yikes. I'll definitely need to clean those up.

2.0 hours. Really? That was 2 hours? I couldn’t believe it. Maybe I fell asleep or something. I have a visitor coming this weekend, so maybe I’ll try to prep some flap parts before then so we can bang some rivets while he’s here.

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Finished Trim Tab

August 20, 2010

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Well, I snuck home over lunch today to make some loud noises (rivet gun) and I got the trim tab pretty much finished. I have one or two more “hard to reach” rivets to set, but for now, I’m going to call it done and focus my attention on the floors and the wings.

The tabs bottom rivets.

Here's the bottom of the tab.

Then, making sure to include the hinge (other builders have forgotten when the time comes to rivet), I got the top of the tab completed.

I do love those gold spars in the background.

Okay, so I’m a dork, and I had to get the hinge pin out and get the thing assembled.

Tab in trail...

Up tab (down elevator trim).

Down tab (up elevator trim). I still have some interference here from the shop heads of the bottom elevator rivets, but I'm going to wait until I'm rigging to sort this out any further.

A quick hour over lunch. 34 rivets set, 2 drilled out.

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More Trim Tab Hinge Drilling

June 27, 2010

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After a motivating afternoon actually getting to sit in an RV-7, I got back to work on the trim tab. Here, you can see my new 3-foot-long MS20257-3 next to the old (and not perfectly aligned) 18-inch MS20257-2 from Van’s. It’s a little wider to give me some more edge distance.

New on top, old on bottom.

First thing, I got the new piece cut to length. It ended up being a little shorter than 18 inches… I made sure the elevator side had a hinge “ear” on each end.

I eye-balled the hinge pin length a little long. Van's tells you the hinge pin they ship with this kit is not long enough to bend and safety to the elevator, and that they'll ship the real one in the fuse kit (or finish kit, can't remember). I guessed it was about 2 extra inches I needed for the bends and then cut the hinge pin.

Then, I spent a good amount of time Just getting everything lined up. I am a little frustrated at this point, because the supposedly straight line of holes on the elevator is not parallel to the supposedly straight line of holes on the tab. This means that with the trailing and inboard edges of the tab aligned with the elevator, the gap between the leading edge of the tab and the elevator cutout is smaller near the root than the tip of the tab.

Inboard and trailing edges aligned perfectly.

Here's my inboard edge.

So, again, I strayed from the directions. I held the hinge in position, making sure the actual pin was directly in the middle of the gap as shown in the picture above at the root (smaller gap) edge and at the outboard (larger gap) edge. I figured as long as the pin was directly centered, I’d be okay. Then, I clamped it in place, and marked a single hole (see below) for drilling. I couldn’t pick the edge hole, because it was covered by my square.

On the drill press, ready to drill a single hole.

I repeated this for another single hole on the tab side, again, making sure the hinge pin was perfectly centered between the two surfaces.

Two holes drilled and clecoed.

At this point, it was close to being locked in place. I did notice that these hinges are somewhat flexible, so while I marked every hole for drilling, I really only drilled a few more before clecoing it in place and match-drilling the rest of the holes.

(A more technical side note…because I upped the hinge size to a MS20257-3, the hinge was too wide to fit inside the radius of the elevator and trim tab spars. When matchrilling, I had to change the order of the skin, hinge, spar to accommodate the extra length, then I went back and ripped a small (1/16″) strip off of the hinges so they would fit nicely in the radii of the spars.)

Here are my feet, ready to keep going on the hinge.

Fast forward after some drilling noises, and here are the two halves, each clecoed to their surfaces.

Ooh, looks good.

I still have a little bit to trim on the elevator skin, but I trimmed enough to allow some motion today.

You can just see the rounded (so it slides in easier) tip of the pin in this picture.

Here’s a closeup of how much extra pin I think I need to make the bend forward (along the spar flange) and then down (along the spar web) to a small safety-wire hole I have yet to drill to safety the pin in place.

Man, that thing is long. (TWSS)

After getting the pin in, I took out every other cleco on each surface so I could move it back and forth.

Neutral.

Tab up (or elevator down trim).

asdf

Tab down (or elevator up trim).

After dancing around for a little due to how great the tab looks on the elevator (and how well-aligned it is), I took the thing apart, ripped the 1/16″ off of each hinge half, and fired up the scotchbrite wheel to clean up all of the edges.

Look on the lower right part of the tab. That little angled cutout is so the hinge hides nicely under the tab skin.

I figured now would be a good time to finish match-drilling the tab. Let’s go find E-718 and E-717.

There they are!

Apparently I thought it would be a good idea to show you my scotchbrite wheel. That little groove is just getting to the right size so I can run the edge of a piece of aluminum down it and it perfectly rounds both sides.

I love this thing.

Back to the tab horn. The directions would have you use the clevis pin (don’t have this yet because I haven’t ordered the tab motor) to line up the two horns. How about two perfectly-fitting #30 clecos?

For balance purposes, I put one on each side.

Three of the holes are pre-punched, and two are not.

Just before match-drilling everything.

All done.

All done. (From another angle.)

I was planning on at least polishing the tab for now, so I marked off where the horn sits. I’ll prep and prime this little area under the horns, but I’ll leave the rest polished. (The bottom of the tab is going to be a good place to teach myself how to polish aluminum.)

The horn location, marked for future priming.

Whew. That was a good two hour work session today. It was like a sauna (more like a steam bath…this is the south!) in the garage today. I kept sweating on the airplane. (People say they put blood, sweat, and tears into their projects. I’ve got one covered, and will undoubtedly bleed and cry because of the project sometime in the future. Have to have something to look forward to, right?)

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