Twisted: Week 105 - Rudder control stops

Thursday 22 August 2013

Week 105 - Rudder control stops

Hours to date: 1069.5

I've not made a lot of progress lately.

Excuses excuses...

Anyway I did manage to get the rudder control stops done.

Figuring out how to do this took a bit of head scratching.

Once the rudder is on there is no access to the area where the control stops need to go - so how to get around this??

I figured on using lumps of plasticine - taped to the mudguard.

Then I put the tailwheel and rudder back on and moved the rudder to the correct deflections (190mm measured at 400mm out from the hinge).

This made impressions in the plasticine of the right depth.

This gave me a starting point for where to put the control stops and how big they should be.

I made them out of micro to start with and roughly the right size and position.

A quick check with more plasticine on top of the micro (once it had set) revealed I still had a little more to add.

So I put some flock on the micro (more than was needed). And left it overnight.

Early the next morning - before the flock had set completely (about 8 hours of curing) - I put the tailwheel and rudder back on and did my deflections again.

This time the tailwheel fork was able to make impressions in the flock in the exact place for the deflections I was after.

Then I just let the flock set completely and hey presto the control stops are now perfect!

I may add a little more micro to the inside and perhaps a layer of glass on the edges of the micro to make the control stops a little more beefy - after all they will have some force going into them if the pilot slams the rudder to full deflection (I can see this rough treatment happening during aerobatics).

I've also begun the task of redoing the horz stab securing pins and front bearings.

It wasn't too hard to remove the old pins and bearings - the Dremel made light work of it.

The technique I'm using now for getting the elevators (and tailplanes) to match up in angle of incidence is as follows.

Clamp the outboard end of the elevator (using 2 wooden blocks to spread the load and make sure it is completely in line with the horz stab).

Then move the horz stab up or down until the inboard end of the elevator lines up with the trailing edge on the fuselage.

Flock in the front bearing.

After this has set the securing pin can be done - and will be in the right place as the incidence has already been set by the front bearing.

My mistake before was doing the securing pin first.

Lets hope this works out.

I am having next week off work so I hope to make some good progress.