4th May 2008 - Engine mountings

Used the clamped on engine-mount mountings from yesterday as guides to drill the jig to 3/8" at the four corners using the pillar drill. Then fastened the engine-mount mountings onto the jig and clamped this to the fuselage. The use of the jig ensured that the engine-mount mountings are exactly aligned with the fuslage datum both horizontally and vertically. Tack welded the engine-mount mountings in place in the fuselage and then removed the jig to final weld them and the firewall diagonal into place. Replacing the jig afterwards confirmed that nothing had moved and measurements proved that the two diagonals across the engine mounts were accurate within measuring tolerances. Cut four 1.5" lengths of 3/4" * 0.156" tubing that will form the corners of the engine mount itself and welded these to 1-1/2" washers.

3rd May 2008 - Engine/gear mount preparations

Next job is to construct the engine-independent part of the engine/gear mount so the fuselage can be put onto its running gear. I have fabricated a jig to use for building the mount out of 30mm square * 3mm box section steel. This is sized such that the engine-mount mounting tubes (29th April 2008) which will weld into the fuselage are roughly centred in the 30mm section. As can be seen, these have been clamped to the jig which will then be removed to drill 3/8" holes. The engine-mount mounting tubes can then be bolted to the jig before they are tack welded into the fuselage. This will ensure that they are square and that the hole spacing can be exactly reproduced in the engine/gear mount itself. Additional members can then be welded to the jig to support the tubing that forms the gear mounts etc.

1st May 2008 - Elevator pushrod completion

Installed the elevator pushrod support at station 111. This comprises a half diagonal of tubing positioned to carry the pushrod support in a straight line from the control mechanism to the elevator horn. In my case the pushrod runs through a 3/4" linear bearing which is mounted in a 1-3/8" section of tube welded to the half-diagonal. The bearing is secured in the tube using a grub screw. This provides a very smooth support for the pushrod. The second picture shows the bearing partially inserted into the mount.

30th April 2008 - Elevator pushrod preparations

Jigged up the location of the Elevator front spar where the elevator horns mount. This allowed the measurement and construction of the elevator pushrod. This revealed that the pushrod would foul on the fuselage diagonal originally running to station 163. This mean't cutting the tube off the 163 cluster, shortening it to clear the pushrod and then rewelding at about 159 and making good the 163 cluster. The elevator horns are jigged to a 13 degree forward tilt at neutral stick position. The plans show a strengthening plate at the forward end of the pushrod where the busing attaches that links to the control mechanism.

Strengthening was also added at the rear end as the joint is critical to having elevator operation.

Finally, the horizontal stabiliser (HS) front attach plates were welded to the fuselage. These will be drilled in assembly for a range of HS incidences to allow the aircraft to be trimmed for neutral elevator trim at cruise speed in order to minimise drag.