Time for some patience

Another major milestone this week; dialing in the monocoque's fixture.

While fitting the frames, each station plate (support) only needed to be assembled correctly to ensure the frame was true to the required shape. Now that we are gearing up to fit skins and stringers, it is very important that the entire fixture is true, and that each frame is in the correct position relative to the datum.

An important part of setting the fixture up has been fitting the spine with a tension rod on the lower side, without this, a fixture of this length would sag. In fact, our initial reading showed that there was a sag of 1/8th of an inch in the centre. This negative 1/8” was adjusted to a positive 1/8” to help prevent sag as we assemble everything. Our next step is to correctly set front-most and rear-most frames to align datum marker, and then we can go frame by frame in between.

Here you can see the steel tension rod in position, without this, the fixture would fall out of alignment as weight (parts) are added. Tension is applied using a turnbuckle mounted centrally along the rod.

When we designed the fixture, we built in many adjustments to ensure accuracy; now it is time to very patiently adjust every one of these to get JP843 true to the original design.

Markers were built into our station plates for each frame, these identify horizontal and vertical datums for each frame. We are using strings to rough align these, and will finish the fine tuning with the laser. You can see here that some frames are not where they need to be!

Horizontal strings are added for each frame to help show level to datum, these are in addition to a standard level and the laser level.