Monday, 24 June 2013

Week 97 - Horz Stab pins

Hours to date: 985.75

Onto bonding the horz stab pins themselves now.

Quite a focusing job this one.

As you will see below I put parcel tape everywhere in case any flock would run out.

After establishing where the hole would be for the pin in the Horz Stab root rib I drilled that out and made it a touch bigger - about 12mm (to allow for any movement of the horz stab to set it on the right angle).

I made a little funnel out of a mixing cup. Then mixed up some fairly runny flock (unlike the usual consistency you are aiming for - 'peanut butter'). So it would flow into the cavity in the horz stab.

After that it was just a case of pushing the horz stab home fully and rotating the fuse to as vertical as possible (so the flock wouldn't run out).

I left it like this for 5 hours until the flock had started to go off before rotating it back to the horizontal (I only did this so I could close the garage door).

Bit nervous the next day but it was all fine and the horz stab released out fine (after taking the pin wire out).

The wire goes in very easily now and feels very solid and secure - so I'm glad I went with Pete's bush mod here.

As you can see from the last photo the horz stab on the starboard side does not match very well with the fuselage root. A bit upsetting - not exactly sure how to fix this so will contact Pete about it.

On the Port side it does match up perfectly at the leading edge but then there is another problem - a big gap underneath (will post a photo next week). This will require a lot of body filler to put right - adding to the weight, not good. Also the front pin is way out with the hole drilled by the factory so will require a bit of work to put that right. Frustrating stuff.

Next job may be the elevator hexes - which will be bonded into the elevators and determine the control surface travel - so a bit critical to get right.

Packing tape everywhere

Funnel for pouring runny flock into the cavity.

Going vertical for it to set.

Figuring out where to route the trim cable (and drilling holes for the indicator wire)

First pin done. Not too much overspill of flock.

Onto the second pin

Starboard horz stab leading edge to fuselage root gap.

Tuesday, 18 June 2013

Week 96 - Horz Stab securing pins and wires

Hours to date: 974.25

Now the weathers picked up I've moved back onto the tail area.

First job is to install the securing wires that hold the horz stab pins in.

Once again I have copied Pete's modification here as he says the factory method doesn't make for the most user friendly result.

So I bought some Stainless bushes (with a 10mm inside diameter) and drilled out a hole just big enough to accept the securing wire with it's plastic sleeve.

I then superglued these into the tail and covered the whole lot in flock (as per the instructions).

When that had set I pulled out the wire and then cut away the plastic that was left inside the bush. (using a scalpel).

The wire goes in very easily and reliably every time now with this mod.

After that I bonded in the wire security hooks with flock and a layer of glass.

Next job is to make a hole in the horz stab. Then pour flock through that hole into the cavity I have made earlier (see earlier post from last year - done before bonding in the root ribs). The horz stab is then pushed onto it's ali tube all the way up to the rib and the flock is left to set inside the cavity thereby securing the pin.

As you can see below I also bought some composite securing threaded posts.

These are available from a company in Germany called R&G Faserverbundwerkstoffe. (Try pronouncing that after a couple of beers!)

They are just stuck on with flock (which oozes through the holes) and then a layer of glass and provide a great way to secure wires, P-clips and the like.

Pete uses them extensively on his Twisters.

Stainless bushes for securing pins

Stuck in with Superglue first

Inside view before encapsulating in flock

Composite securing threaded posts

After flocking and bending the securing wire

Pin sits very securely in the bush

After cutting out plastic sleeve - orange stuff is plasticine to stop flock going in end of bush

Wire securing hook bonded in

Monday, 10 June 2013

Week 95 - Trim and Battery cover

Hours to date: 965.75

I finally got the battery box cover done.

6 layers of carbon with 8 layers on the flanges (where they will be bolted).

It's more than strong enough. I did a load test on the lower battery tray too - putting most of my weight on it so it's well strong enough.

I found that using Twill weave carbon was much easier to fit into the tight corners and curves of the battery box. I tried using some Bid I had lying around and it was almost impossible to get it to fit in the shape. So Twill is the stuff to go for if you are working a complex shape.

I got the elevator control rod guide fitted at the rear too - see photo. At the bottom you will note two holes - these are to let any small stones or grit fall out and not get in the guide bearings. Pete says he had this happen once (before he drilled the holes) and thought he had lost the elevator as it jammed solid, scary stuff! 

As you can probably tell I am trying to get everything done in the cockpit section. Once that happens then I can paint the cockpit and install everything back in for real.

With that in mind I built up the Trim assembly.

The manual is somewhat out of date with the parts supplied so a bit of head scratching is required to figure out what to do.

A few extra jobs need to be done to make this work. The small bracket at the end needs the two holes countersinking, easy enough. 

You have to drill a hole in the 'latch' lever. 

No parts seem to be included for the Trim indicator. My kit did not have any wire for it and only one larger wire end - which I will use for the Trim itself. There is one very small wire end which I will use as the indicator itself.

So I followed what Pete did and drilled a hole in a 6mm bolt (for the wire) and fitted two Nylon washers and two nuts that will hold the indicator wire in place. (see photo below)

I also had to make up a base plate for the whole Trim assembly. This is to mount the Trim securely to the cell. I used 8 layers of glass for this and the now familiar (to regular readers) duct tape over a block of wood method.

Also to lock the spring holders on the elevator control rod I drilled out and then cut a thread in the top so a 4mm nut (with the end sharpened to a point) would screw down into the hole in the top of the rivet. This is the same method as described in the manual but the parts supplied do not have a lock nut or thread in them.

The control stick grip is now finished and attached to the control column. I put heat shrink around the wire bundle to protect it and will 'pot' the wire around the hole where it comes out with silicone later to eliminate any chaffing.

Also I now have a spinner and cowling. Matthias has very generously sent me the cowling free of charge - thanks Matthias! The spinner I bought from Hercules Propellors here in the UK.

The cowling is for a Jabiru so it won't fit the UL, but it will make an excellent starting point for the final cowling and should save a lot of time on this job.

Countersink these two holes

Trim assembly - part way through...

Control stick grip finally fitted.

Hole drilled in latch for Trim wire

Thread cut into top of spring mount with sharpened 4mm bolt to secure it in place

Laying up the battery box cover - what a mess!

Cowling and spinner

Rear elevator control rod guide in place - note holes at bottom to let small stones/grit out

Battery box cover all trimmed out - inside view

Trim assembly mounting plate - 8 layers of glass.

Trim indicator fixing point

Trim assembly in place - need to mount at 30 degrees to centreline.

Battery box cover - top view

Tuesday, 4 June 2013

Week 94 - Battery box and Elevator push rod guide mounts

Hours to date: 950.5

The battery box is getting there.

Next up will be the lid.

I've decided the webbing strap is overkill as there will be at least 4 bolts holding the lid on. Plus the baggage shelf will be bolted to the cell and will be hard down on the lid - so that is the backup.

On the control stick I've fitted the trim lever. With the Infinity stick grip there are brass threaded fittings inside for joining the two halves and the lower one of these is ideal for fitting the trim lever. It's what Pete does - so I am just following his lead on this one.

The other thing I've done with the stick is to blank off the trigger hole with the trigger itself. I just filed down the edges until it fitted inside the space and superglued one side down.

Onto the elevator push rod guide mounts.

Pete has loaned me a mould for the rear one as the cell is curved here. There is no way the guide could be mounted perpendicular if you just used the edge of the cell as stated in the manual.

I used 5 layers of carbon for this part and pre drilled the hole and grooves for the nylon rollers before installing with flock.

The front guide is an easier piece to work with. Just got to make sure it is mounted at 90 degrees to the bottom of the cell that's all.

Hopefully by next week I should have the battery lid completed. Then I hope to move back onto the tail as the weather has picked up here now and it is good to open the garage door (which I need to do to work on the tail).

2 more layers of carbon on the top

Battery will sit like this - dots indicate where the terminals will be.

Mould Pete lent me for the rear of the cell

Stick grip with Trim installed and trigger modified.

Rear guide mount made ready for bearing to be mounted

Front guide flocked in place

Rear guide flocked in place. Just got to drill out the cell now.