Monday, 29 September 2014

Week 164 - Canopy - DV panel

Hours to date 1473.25

Just a short post this week about fitting the DV panel to the canopy.

Before I get onto that I thought I would let you know how the canopy bonding turned out.

I left it to set for 48 hours and applied a little gentle heat during this time to help that  - using my fan heater through the baggage end gap.

All seems well - the perspex is very securely bonded to the frame with almost no air bubbles (a couple of very small ones but nothing to worry about).

As a side note I did mix up my flock a little runny compared to the normal 'Peanut butter' consistency - I think this was the right thing to do to get the perspex to bond without air bubbles.

As you will see below there are a couple of areas where the flock oozed up into the perspex (under the tape at the front - and over the tape where I had put the wooden block on the outside). I should have got back inside to scrape these off but I was in a rush going out (hot date!). 

Best never to rush such a job...

Anyway they are all fixed up now with many careful hours with a Stanley knife and Dremel (masking the canopy to protect it with 4 layers of duct tape first).

Pete puts a foam strip around the top edge of the frame to stop the flock oozing out but I felt uncomfortable doing this as my canopy had precious little surface area to bond in a few places and the foam would reduce that still further.

All that is left to do is to fit the frame and canopy to the fuse properly now - there is a bead of flock that needs to be sanded down and I will then use micro to make the whole thing perfectly smooth after that.

Onto the DV panel.

There is nothing in the instructions about it but just look at a few photos and you'll figure it out.

The only tricky bit is fitting the actual panel, as it is spring loaded.

The best thing to do is fit one of the canopy rails (the lower one) then put the DV panel into the lower rail, and while holding it in, fit the top rail (do this in the fully closed position as this is the least amount of stress on the springs). Three hands would be useful here! It can be done by two believe me...

Bit of flock that oozed under the tape - now gone.

DV panel fitted

Trying it on for size!


Saturday, 20 September 2014

Week 162 (2) - Flap drive and Canopy

Hours to date: 1460.5

Onto the dreaded flap drive job!

Well to be honest so far it has not been too bad at all.

First thing to do was put a 6mm thread into the flap securing bracket on the wings. Easily done with the drill method (as described in a much earlier post about the elevators). The manual is a bit confusing here as it states a 372mm distance in the text (between the trailing edge of the flap and the trailing edge of the wing) then states 370mm in the diagram. I went for 371mm.

To make things easier to move around I decided to put the Twister on all 3 wheels for the first time.

Onto the flap drive - I spoke to Johan in Belgium first to see if he could offer any advice or 'gotcha's'. As it turns out he described the method that I was going to use anyway but added something really helpful - thanks Johan!

That extra something was the use of a straight rod (or tube as in my case) as a device to get the holes lined up before drilling out to their final size.

As you will see below it worked out really well and I only have a 1 to 2mm gap in the safety cell holes to the flap torque tube.

The photos below better describe the method so please see them to understand how it was done.

I found out afterwards that the torque tube supplied was 24mm too long. A careful bit of measuring and cutting later had it to the right length.

I then riveted one end of the flap drive onto the end of the tube (as per the instructions). The other end is riveted on after the aircraft is painted.

I made up the flap torque tube drive and pre drilled my holes to secure that in the drive arm to make life easier later on.

Good news is - I finally got the Port wing on and the spar pin in. This allowed me to fix the rear wing pin bearing and also fit the front wing pin bearing after that. All that's left to do now is fit that wing to the fuselage (by filling the gap with flock).

The starboard wing has not proved so straightforward. I spent the better part of a day trying to get it to fit and ending up finding out it was the front wing pin that was fouling on the wing inside. I've fixed that and it should be okay to fit now.

But before I do I'll need to fix the rear wing pin bearing on that side too as I found out that it was 1mm out. So the lesson here is - do not fit your wing pin bearings in the factory drilled holes! Wait until you can put your wings on and do it then.

I'll end this post by talking about the canopy. 

I've made up the retaining cable - using a Swaging tool for the first time - things worked out good.

The manual states that you need to fit two threaded hooks (one in the canopy frame and the other onto the fuse on the inside) as securing devices for the retaining cable. Guess what? They were not included on my kit so I had to make a trip down to my hardware store to buy some - best to do this job before fitting the perspex to the frame as it would be impossible to drill a pilot hole afterwards.

After many many hours of fitting the perspex to the frame I was finally ready to bond it in place - a very long and frustrating job doing the fitting - take your time and be patient (lots of sessions rather than trying to do it in one go).

I masked off the canopy frame (where it was painted) with duct tape.

I also masked off the inside of the perspex - where I had previously put masking tape (as a guide of where to key up the edge to be bonded).

Finally when all of this was done and the frame was cleaned with Acetone - and the perspex with meths (do NOT use Acetone on the perspex it will graze it and most likely melt it!).

Following Pete's advice I carefully drilled 4 holes into the perspex and frame on the 4 corners (1.5mm holes) for some securing nails. These are then waxed for releasing.

Then I mixed up a heap of flock (175 grams to be precise) and put that all around the frame edge where the perspex would bond to it. I thought I had overdone the flock and put too much on but it turns out that was just the right amount - I only ended up scrapping about 25-35 grams off afterwards.

With the help of my brother we lowered the canopy carefully onto the frame - lining up with previously marked lines front and back.

After that I just gently pressed the frame in all round and then crawled inside the fuse (through the baggage bay end hole) and scrapped off the excess flock on the inside with a sharpened stirring stick.

As you will see below one area would not sit flush with the frame so I resorted to gently pressing it in place with a block of wood while it set.

We'll see how it all turned out next time I post!

6mm thread cut into the flap securing bracket.

On all 3 wheels for the first time!

Determining position of holes for the flap torque tube by putting the end attachments on the flaps and sliding the wings on and marking where they touch on the fuse root.

Using a straight tube to determine where to drill out the safety cell hole - remember that the fuse wing root is not straight - dihedral! Use a spirit level to get the tube square.

Broader view of above

Factory marked hole is pretty much spot on this side - miles out on the other side

Fixing the port wing rear wing pin bearing

Use the cut out from your hole saw of the outside hole to mark the inside hole in the safety cell

Tube in place with 1-2mm gap all round.

Note how flap drive sits square but wing root has angle for the dihedral

Flap torque tube was too long - by 24mm

Port side riveted to the torque tube

Flap drive motor and arm assembly made up.

Port wing pin finally in!

Flap drive in place - arm will be riveted later.

Flap drive 'box' in place.

Swaging tool - poor mans version but works okay

Canopy retaining cable made up

Ditto - with heat shrink on the ends.

Canopy retaining cable threaded hook and securing nails for the canopy fitting job.

All masked off and heaps of flock applied to the frame edge

Leaving it to set with block of wood for stubborn area.

Arrow shows where nail is - these will be removed later and the hole filled.

Monday, 15 September 2014

Week 162 - Canopy Part 5

Hours to date: 1433.5

Sorry for the big gap in posts but I have had my parents over visiting from New Zealand, so things have been rather hectic for me.

Onto the canopy.

The opening and emergency release mechanisms are both completely finished.

As you can see below I decided to paint the emergency handle red - I think it helps with other pilots who don't know the aircraft not to pull on it - it will of course be placarded also.

On the emergency release side I struggled to drill the hole for the roll pin that secures the handle in place. The release pin is made from stainless steel which is notoriously difficult to drill. I only have a hand drill (a drill press is much better) and even though I bought some Cobalt drill bits they didn't work. I then bought a Carbide drill bit and I made some progress with it before I work hardened the steel. Feeling a bit frustrated by this point I ended up taking it to a local engineering shop and getting them to drill it and fit the roll pin. It is one of the very few jobs I have not done myself on the kit so far. (I actually fitted two roll pins - one either end of the handle - just to be sure).

Once the handle was painted I fitted the release pin back into the fuse and bonded it in place with carbon and flock (this was only on the fibreglass tube section that the pin slides in).

After that I flocked the panel that had been cut out of the side of the cell back in place and then put one layer of glass over all the joins with a 50mm overlap.

On the opening side I have painted the metal parts black - and left the parts that slide into the mechanism bare (they are stainless so will not corrode).

Everything works well - the opening is easy, with no play and the emergency release has a nice hard 'pull' to it which is what I wanted. Use WD40 to lubricate these mechanisms but only after they have been bonded and painted.

The only thing left to do is bond the canopy perspex to the frame - I have spent many hours so far fitting it to the frame. Still a little more to do. I have used a hand sanding method as I don't like the idea of putting a power tool on the perspex. Pete says he uses an 80 grit flexible sanding disc on an angle grinder. I don't have an angle grinder so I am resorting to the 'armstrong' method of hand sanding.

I am finding that the more you do the more you have to do (if that makes sense) as the canopy settles onto the frame. It's not a job you would ever do in one hit - best to have several sessions of it, taking a little off each time as you go.

An update on the frame fitting to fuselage. I thought I had added plenty of micro to the fuse before putting the frame on - and indeed it did ooze out of the sides all round on the outside - but as it turns out I did not add enough on the inside area. Not a major hassle as I just had to have 2 goes at doing this job. Adding more micro to the fuse and giving the frame another wax on the packing tape before closing it down. With the waxed packing tape it released very easily.

I've moved onto the dreaded flap drive job now (which Pete says is the worst job on the whole kit) so will post an update on that soon.

Rear of canopy fitting very nicely to fuse now with micro added

Ditto at the front

Fuse has micro added around the canopy area and lightly sanded - ready for paint

Beginning to fit canopy to frame - don't do it off the plane as I started to do here!

Emergency release bonded in place and the cutout panel flocked and glassed over

Opening mechanism all done

Emergency canopy release all done