Wings « Matt's RV-7 Project

Archive for the ‘Wings’ Category

Flap actuator safety hole

Wednesday, April 19th, 2006

The only thing I got done tonight was drilling this little hole at an angle through the end of the flap actuator. In the photo, you can also see the first hole I tried to drill. The bit broke off in the hole and I had no way to get it out, so I had to start another hole. The end of the actuator was also kind of scraped up after all this, so I sprayed some more black enamel on it.

The idea is that you put safety wire through here and it prevents the jam nut from backing out as the flaps go up and down. I'm dubious that this will work very well, so I used permanent threadlocker on the rod end bearing and jam nut when I threaded them into the actuator.

Posted in Flaps, Fuselage |

Installed flap torque tube

Sunday, April 16th, 2006

This afternoon's mission: install the flap torque tube. The clevis ends of the weldment got drilled and reamed up to 1/4" for the bolts, and then I drilled and split the center bearing block. My block as supplied was about 1/2" longer than the plans call for, which made where to locate the aft bolt hole a head-scratcher. I decided to put it in the same place it would be if the block was the size called out in the plans, instead of putting it 1/4" from the edge. This turned out to be a good idea (see below).

The weldment is inserted into the end bearing blocks, and the whole mess is put in the baggage bay. It's a tight squeeze but it can be wiggled into place. The center bearing block goes over the left-center subfloor rib. I've heard that some people have trouble with the non-powder-coated part of the weldment ending up in the wrong place, but you can see that mine lined up okay.

After making sure the center bearing block is centered over the rib, I drilled down through the block into the floor and rib, then removed the whole mess and put in nutplates to capture the bolts. Good thing I decided to move the aft hole away from the edge of the block, or the #10 hole would have been uncomfortably close to one of the #8 nutplates that holds the tunnel cover to the ribs.

I notched the tunnel cover so it can be removed without unbolting the flap bearing block. The left side baggage floor is captured by the flap block, so it will be a little harder to remove easily. That means I'll put the strobe power supplies under the right-side baggage floor, which I was planning on doing anyway for lateral balance purposes.

The whole collection of parts is now bolted in place yet again, although it will certainly be removed and replaced several times later on.

So, the flap torque tube is fitted and installed. Next up is the motor and its housing, probably not until next weekend when I have some time to work.

Posted in Flaps, Fuselage |

Autopilot work

Sunday, April 2nd, 2006

I broke out the TruTrak pitch servo today. Here's a shot of the servo and its bracket, next to the skimpy instruction sheet.

I drilled out four of the rivets in the F-729 bellcrank rib, then back drilled the bracket in place. Once the position was fixed, I marked and drilled three more #30 holes in the upright part of the bracket and four #40 holes through the bottom flange and belly skin. The holes in the skin were dimpled using pop rivet dimple dies.

After priming the bracket, I riveted it in place. Four solid rivets to replace the ones I drilled out, three pop rivets below where the squeezer couldn't reach (i.e. I didn't feel like shooting and bucking while leaning into the tailcone). Then Mary helped me back rivet the four rivets through the bottom flange (because she is awesome). The bracket is very secure and sure as heck isn't going anywhere.

Here's the servo temporarily installed, to test how the linkage works. It looks like it will be fine. Even with a stack of washers for spacing, the short pushrod isn't completely straight, but apparently that's normal.

While I was messing around with autopilot stuff, I removed the roll servo from the wing, tightened the screws that keep the DB9 connector in place, and put everything back in. This would have been easier to do all at once the first time, but of course I wasn't thinking about the wiring when I installed the servo. I played around with some cool slide-lock connectors that I bought from Digi-Key, thinking that I'd be able to use them instead of screws, but they didn't fit. Oh well, there probably won't ever be a need to remove that connector, and if I really have to I can just pull the servo out again through the access hole.

Posted in Fuselage, Wings |

AOA Drain

Wednesday, February 1st, 2006

Tonight I fabricated a simple drain tube for the upper AOA port. It's intended to channel the drained water down and out of the wing, as well as helping to guide the pin to the drain plunger. I started with a VA-112 fuel tank drain flange, which is normally mounted on the exterior of the fuel tank skin. I drilled another set of mounting holes and countersunk them so I could mount it the other way around:

Here's the drain hole and the rivet pattern. These rivets will be flush, fulfilling my goal of having none of this stuff poking out in the breeze.

And here's a shot of the finished product. A piece of clear vinyl tubing from the aviation aisle at Lowe's is slipped over the drain, and feeds down to an AN816-6-2D pipe nipple that I had lying around. That's kind of an odd size for normal use, but it worked great for this application. The tubing is a tight enough fit on both ends that I didn't bother with hose clamps.

The angle between the two ends is a little funny because I didn't plan to do this whole thing originally – I just located the hole where it was a straight shot up to the drain plunger, which makes sense if you're just going to use the drain pin without a guide tube. The bend in the tubing is due to the fact that the upper and lower skins aren't parallel here, which I'll allow for next time. I'm pretty happy with how this first attempt turned out, though.

This was probably overkill from the point of view of draining out water – I'm given to understand that hardly any water ever enters the AOA port in the first place – but it does a dynamite job of guiding the pin to the plunger when you're poking it up into the wing without being able to see what you're doing.

Posted in Wings |

Roll servo wiring

Sunday, January 29th, 2006

I was travelling or doing errands for most of the weekend, so I didn't get anything done on the plane besides running the wires for the autopilot roll servo. Two adel clamps and some tie wraps keep the wire bundle safely away from the moving parts. The only snafu is that there's no way to tighten the screws that hold the d-sub connectors together unless you take the servo completely out. I think I'll try to find some thumbscrews to use there instead.

I bought this cool label maker that can print directly onto shrink tubing. Now I won't forget that this connector at the wing root is for the "roll servo". Okay, maybe this didn't need to be labelled, but I had to test out my new toy.

Posted in Wings |