| day |
notes |
hours |
| 25 |
Assemble all the mass balance weights TP19 onto the TP18 arm and hold in place with a big split-pin. Position the containment bulkhead side pieces and mark the fuselage bottom for their locations with a felt-tip pen. Chamfer the bottom edges of the front part of the bulkhead to approximately match the curve of the fuselage and check clearance from top of pitch pushrod. Minimum is about 9.5mm at full down elevator (ie mass balance weight up) so mark lines 5.5mm up from bottom edges and trim off. Minimum clearance now about 4mm but maximum still about 6mm at full up elevator (weight down). Trim off another 2mm from bottom edges. Now almost in contact at full down elevator (weight up) and 4mm clear at full up elevator (weight down). From the 60mm wide piece removed from the top section of the bulkhead mark and cut a 120mm length for the lower containment bulkhead. Mark a centre for the 25mm radius. Need to spot-attach the front bulkhead to the side pieces but can't do that in one go as the sides have bowed slightly since they were cut out. Lightly clamp at the centre and apply Araldite Instant to the top ends of the sides. As the epoxy is not going off in the advertised 90 sec because of the low temperature (5.6C) clamp the sides in the correct position against the front bulkhead rather than holding by hand. Make 25mm radius at top edge of lower bulkhead with 50mm Forstner bit. Mark and drill 4.5mm fixing holes with a wood boring bit. Now that the epoxy blobs have cured, remove clamps and re-check alignment of bulkhead with pitch pushrod. The straightening of the side pieces has raised everything and so increased the clearance slightly. Will have to re-trim to correct once fully bonded. Mix more Araldite Instant and apply to middle and bottom of side piece edges. Position to get sides straight and symmetrical then clamp. |
1436 |
| 26 |
Epoxy blobs all well cured now; unclamp containment bulkhead and try for fit again. Max clearance from the pitch pushrod is now about 5mm so it needs about a millimetre removing from the base. Take a bit off the base of each leg with a coarse rasp, trying to maintain symmetry. Try again for fit and the max clearance is now fine at about 3mm. Put the weights on again and find that they are rubbing on the starboard inner side of the bulkhead at the top of the travel. To correct that, need to take a little more off the bottom of the starboard leg. Just a small amount does the trick, but the pushrod is now just catching the bulkhead at full down elevator (weight up). Relieve the curve of the bulkhead slightly (less than a mm) with a half-round file and all is well again. |
1436.5 |
| 28 |
Set up the containment bulkhead to mark the position of the holes for the lower containment bulkhead mounting, but notice that one of the blobs of epoxy has come adrift at the top of the bulkhead. Wedge the TP18 arm at top of travel to give maximum clearance between lower bulkhead and pushrod and position the lower bulkhead using a scrap of 3mm ply to space it away from the pushrod. Clamp in position and spot through the holes with the 4.5mm wood bit. Unclamp and remove. Mix up more Araldite instant and put a fresh blob on where the parts have separated. Lay flat on a piece of paper with weights to keep it all square and in contact while it cures. |
1436.8 |
| 29 |
Clean epoxy nibs from containment bulkhead. Check position of lower part of bulkhead and mark its final position. Drill through the holes with a 4.5mm wood bit, then open up to 4.8mm for the bolts. |
1437.1 |
| 30 |
Clear accumulated stuff from small curing tent and get it ready for use. Cut 2 pieces of BID at 45 degrees to each other to cover the front face of the containment bulkhead. Lay them out aligned on top of each other on a piece of polyethylene sheet. Unstick resin pump pistons as usual, with a couple of strokes to waste. Mix 3 strokes epoxy and wet out the 2 layers of BID. Paint remaining epoxy onto face of bulkhead. Set bulkhead down onto BID, then turn over and peel off polyethylene. Stipple out a few dry patches and apply peel-ply. Leave in curing tent with heater thermostat set to 3.5, giving 29C, 34% RH within a few minutes. Layup well cured by bedtime; 30C, 20& RH, turn off heat. |
1438.1 |
| 31 |
Remove peel-ply from yesterday's layup. Trim the straight edge with a padsaw and the inside curves with a diamond burr in the Dremel. Smooth off all edges with Perma-Grit files. Measure up sides for layup and mark out 4 off BID strips about 140mm x 600mm, in pairs at 45 degrees to each other. I hadn't bothered to label the small amount of epoxy left in the mixing cup, but it has set so hard it shatters when I try to pop it out, so that is OK! |
1439.0 |
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