       Working on Chpt 10 - Canard Construction updated: 19/08/2008
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Step 3 – Attachment Tabs and Installation In this step the 2 attachment tabs on the main gear strut are fitted and then the strut is installed into the fuselage between the landing gear bulkheads. Before making the jig box the strut was lined up against a piece of ply board set-up vertically against the end of my workbench. I marked the concrete floor with the FS108.25 and FS117.5 reference points as per plans and determined the centre line ,which I then carried up onto the back board. Once the centre line was determined I then marked the 2 vertical 13" lines, either side of the centre line and marked out the location for the 1/4" pilot holes for the attachment points.
I then proceeded with manufacturing the jig box as per plans, and when I was happy with the final set-up the jig was glued to the strut using Automotive Blade Putty (Bondo). I left this to set over night and the following day proceeded with marking up my work bench top with the reference points as stated in the plans and also doubled checked the workbench for level, before placing the strut onto the table. The jig lined up perfectly with all the reference lines and the legs were level as well. I then dropped a Plumb Bob from the LE of end leg to check the FS108.25 reference point. The plumb line was forward of FS108.25 by about 1/8", which I corrected by shimming the front end of the jib box with a single mix stick on each side. When I was happy with the over set-up of the Jig and Strut, I then securely clamped the complete jig down onto the table using 2 adjustable plastic claps on either side of the jig.
I then filled all gaps between the Jig and Strut with Bondo and foam off-cuts to create a smooth transition from the strut onto the jig. The sides of the jig where covered with clear plastic box tape and the bench top was covered with plastic sheet before glassing started. I also marked the 3" lines across the strut using a piece of stiff plastic and joined the lines to the 3" circle on the sides of the jigs.
I cut and wetted out the UND & BID cloth as per plans at 3.8" wide and 15" long and completed the lay-up on both sides, in just under 2.5 hours with the help of my better half. The tabs were clamped between 4 pieces of wood covered in box tape and left to cure. I carefully measured the inside and outside dimensions of the wooden clamps, during clamping to ensure I did not clamp more on one side than the other.
After cure I removed the clamps and proceeded with marking and drilling the 4 x 1/4" holes in the tabs using the 2x4 alignment fixture as per the plans. I double checked my reference marks on all 4 tabs before proceeding to ensure that they were all the same and that nothing had moved during the glassing process.
After drilling the 4 tabs, the Jig box was removed with great difficulty as the Bondo had really stuck hard onto the Strut and would not budge. I had to partially dismantle / destroy the jig and use heat to finally get it off the strut. The tabs were then trimmed to 3" wide over the strut with a 1.5" radius on the ends before moving onto glassing the inside. The strut was laid on its side and the 1/4" holes filled with wax as recommended in the plans. The strut was then rigged across the end of my work table in an upright position and securely clamped, so that it wouldn't move. All the UND (Lay-up #3 - 20 layers) and BID (Lay-up #4 - 25 layers) cloth was cut the night before in preparation for the inside lay-ups. Note that the number of plies for the UND and BID are reversed compared to the outside lay-ups #1 & 2.
The inside corners were filled with flox before applying the first 20 plies of UND, followed by the remaining 25 layers of BID. The lay-up was then peel plied before clamping with wooden blocks. I inserted spacer blocks on the end of the clamping arrangement and measured each end to ensure that the clamps and wooden blocks remained parallel to the inside tabs whilst curing. The complete lay-up took about 3 hrs to complete. After cure I used the Fein and a course metal file to trim and shape the outside tabs to conform with the inside tabs, which had already been shaped to the current radius. This was quite a tedious process and took a couple hours to complete and quite a lot of sweat.
In preparation for setting up the Strut in the Fuselage, I removed my work table from the trestles and placed the fuselage upside down onto the trestles and ensured that the complete unit was level in both directions. The fuselage was then clamped securely to the trestles. I didn't want anything moving whilst trying to fit the strut in and out of the fuselage and already knew that this process would take a lot of fiddling to get all the reference points to line up before drilling the holes. With a cross hair laser and a plumb bob the fuselage centre line and FS108.25 reference lines were marked onto the concrete floor. The strut was then placed into position in the fuselage and using wooden spacers I set-up the strut, so that it was in the middle of the Aft & Fwd bulkheads and centred with the fuselage centre line. Using 2 x 1/4" pieces of 12" long round bar as guide pins, I then checked the accuracy and line up of the 1/4" holes in the fuselage and strut tabs. I found the left and right hand sides of the fuselage, were keeping the strut from fitting correctly and the complete strut was a little high. I profiled the sides to conform with the strut, with a little extra for clearance and then refitted the strut. This time the left hand 1/4" holes lined up perfectly and the 1/4" guide pin went all the way through, with the strut still lined up with the fuselage centre.
At this point I stopped to check level and dropped plumb lines from both legs to the 108.25" reference line on the floor and shimmed the right hand side a little to get a perfect set-up on both legs and 0.0 level. The 1/4" holes on the right hand side bulkheads were about a 1/4" out, so I redrilled to pickup the holes in the tabs and fitted the guide pin. Again I rechecked the set-up and was very happy, as the strut was level and both plumb lines were spot on the 108.25" reference line. I then removed the chapter 9 "CG Products" metal parts from storage and placed them on the work bench and re-read the plans, so that I fully understood how they went together. The quality of CozyGirrrls parts is impressive and I was glad I didn't have to stop and make these items at this stage and pressed on with fitting MG-1 & MG-2.
Using a small amount of 5 minute epoxy, I fitted all the MG-1 & MG-2 plates into place and secured them using a 1/4" bolt through the centre guide hole. I then proceeded to drill out the 4 x 5mm holes in the MG-2 plates, using a right angled drill adaptor. The plates were then removed and reinstalled with flox and four MS24694-S60 screws and MS21042-3 nuts. Using the 5/8" dia. spot facing tool the 1/4" guide holes were bored out to 5/8" as per plans and the MKMG-4 S/Steel bushing fitted with flox. The MK100 (1/2" x 10-3/4") studs were then fitted to ensure the bushes stayed aligned during cure. The Spot facing tool purchased from Wicks worked fine and I had all 4 holes bored out to 5/8" in about 1 hour. Just keep it slow and steady without applying too much force, this keeps the heat down.
Using the 3/4" cutter on my Spot facing tool I then proceeded to bored out the 1/4" guide holes in the Strut attachment tabs, using the same drilling sequence as specified in the plans. The two MKMGA (-C2) tubes obtained from "CG Products" were slipped into place and the strut was placed back into the fuselage to recheck all dimensions before permanently floxing the MKMGA's into place. I have a slight miss alignment on the left hand side and the 1/2" bolt needs a little persuasion to get it to travel all the way through, with the same amount of difficulty pulling it out. The right hand side was a perfect fit and was easily fitted and removed. The landing gear was then removed from the fuselage and foam was added to the bottom of the MKMGA (-C2) tubes. The foam was microed and the gaps filled before the 2 layers of BID were applied. I did not bother dimpling the tubes as suggested in the plans, as the CG supplied tubes come knurled providing more than enough purchase for the Bid cloth.
The 5/8" washers were floxed into place on the outside of the tabs and then glassed with another 2 layers of BID. Everything was peel plied and left to cure.
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