LH WING FLAP AND CONTROLS
According to the plans, the flaps are the easiest controls to build. The plans are right. The first 8 pictures of the left and right flap assemblies will be the same in both sections. The narrative will be the same as well. This is because I did the preliminary work on both flaps at the same time and decided not to differentiate.
Above left are the parts for both the left and right flaps just prior to beginning the construction process. Above right Ritchie has begun to remove the protective coating from the inside of the flap skins. As per my normal procedure, I will leave the coating on the outside of the skins for now. In case you didn't read the narrative on the ailerons or the Forward Fuselage, Ritchie is from Guayaquil, Ecuador and is here for his Summer school vacation which is in February and March as opposed to July and August in the US.
In the two photos above, Ritchie is assembling the flaps with clecos to make sure everything fits as it should. Teaching other people how to do these tasks makes assembling this airplane all the more enjoyable.
The photo above left shows both flaps cleco'd together. At right above, the 1.5 X 2 X .125 angle supplied with the kit is in process of being sawed into two re-enforcement angles, part number FL-706A, that get riveted to the inboard rib and the inboard end of the forward spar.
Above left is a photo of Ritchie drilling the fastener holes in the FL-706A re-enforcement angle and the FL-703 spar. Three holes get match drilled to the existing end rib attach holes. 5 more holes get added to the spar web and the re-enforcement. Above right Ritchie has installed the FL-706B re-enforcement for the actuator arm and he is drilling it to fit the inboard rib. All of the holes are in the e-enforcement but only one hole is in the rib and that is the bolt hole for the rod end. You cleco the FL-706B to the FL-704 through this hole, clamp the FL-706B to the FL-706A and drill all the holes with a #30 drill. After all of the holes are drilled, the hole that was originally used to locate the FL-706B gets enlarged to 1/4" and a 1/4" nutplate gets installed on the rib.
Above left Ritchie is de-burring the lower skin on the de-burring wheel. Above right the dimpling process has begun. In this photo Ritchie is working on the upper skin.
I did not notice this until now. You have to drill two holes in each FL-705 interior rib, one at the aft edge of the lower angle and one in the aft vertical flange where it attaches to the vertical flange of the FL-702. I was drilling these holes as Ritchie was dimpling parts and I noticed a problem. The photo at left shows a gap between the aft vertical flange of one of the ribs and the rear spar (which is actually formed as part of the lower skin). At right is a photo of a rib on the other flap with the same problem. I thought I was going to have to make 8 little shims but the angle between the vertical web of the FL-702 and the lower skin was too great as it turned out.
In order to re-form the angle, I would need to have something that would be at least the width of the upper flange on the web. The long skinny bucking bar that I have been using for almost every off problem it seems, saved the day again. I used it in conjunction with wide flange tool (above left) and I gently re-formed the angle along it's full width. The photo above right shows the gap between the vertical flange and the rear spar is now gone.
The photo above left shows the "pop" rivet dimple die in use on one of the rear holes in an end rib. The aft three holes in the upper and lower flanges of the end ribs were dimpled this way. The very aft one upper and lower was tricky to get the nail through because the distance between the flanges was so small but I managed. The nail actually had to be bent and then re-straightened to get it through the hole. There is a picture of this procedure in the rudder section. Above right is a photo of all of the parts of both flaps dimpled.
I decided to dimple the inboard rib for the nutplate instead of countersinking it (above left). I also dimpled the nutplate. Here is a picture (right) of the beginning of the etch and alodine process. Notice the square object at the left edge of the photo. It is gray Scotchbrite. I have been scuffing the metal with the Scotchbrite as I etch it. This helps the primer to stick later on. It also helps to clean the metal. I found this quote on one of the RV-7 forums: "If you like to wash the dog, then the etch and alodine process might be for you." Well I don't particularly like to wash the dog but I sure do like it when the dog is clean. Etch is what cleans this "dog."
Above left is a picture of all of the parts for both flaps after they were etched and alodined. To its right appears the upper flap skins after they were primed with DeSoto BAC 377 yellow primer. These primed parts do look nice in the pictures.
At left is a picture of the lower flap skins after prime. At right is a picture of all of the flap parts in the booth, ready to be primed.
At left above is a photo of the detail flap parts in the booth after they were primed. At right the four interior ribs are riveted in. These ribs all have to go in first because of the rivet in the aft vertical flange. This rivet would be very difficult to install if the upper skin was attached.
This is a photo, above left, of the left flap with the lower skin cleco'd to the upper skin. The view is looking towards the first interior rib from the outside. At right you can see that we attempted to keep the trailing edge straight and the flap from twisting as we riveted it together. We put the trailing edge as close to the table as possible while retaining enough room for the rivet gun. When I rivet the right flap, I intend to use another table that I have . It has the top overhanging the structure so that I will have more room for the rivet gun.
Above left is a photo of the left flap upside down after the lower rivets were installed in the internal ribs and the spar to lower skin attach. Above right is a picture of the flap on the table. It is still flat and untwisted.
The two pictures above show the beginning of the internal rib to upper skin attachment. This was straight forward and I managed to do the riveting by byself. The very aft rivet on each rib required a bucking bar that is thinner than the standard bars that are sold by Avery or Cleaveland.
Above left is a picture of the left flap after ithe upper skin was riveted to all of the ribs. At right is a photo of the inboard rib for each flap after the 1/4" nutplate was installed.
The photo above left was taken with the flap upside down. The arrow points to an area where a shim is installed. The shim is on drawing 14A and has a part number of FL-708. This almost surprised me. If you look at the canopy installation, the middle brace has a plate .100" thick that is sandwiched between a stiffener and a frame with no shim. This shim is in place because of a overlap between the upper and lower skin of .025". I guess Van's Aircraft has more than one engineer. The photo above right was taken with the flap right side up and the end rib riveting complete.