Week 23 - Rudder, Rear wing rib and Bell crank covers

Hours to date: 247.75

Well it turns out that I was making a mountain out of a mole hill with the bell crank bearing.

I thought I would have to take out the entire bearing which was going to be a real mission as it is hard to get to and I would have been working blind. It ended up being a simple case of turning the inner part of the bearing through 90 degrees and then pulling it out with a set of pilers. So I just have to replace the inner (light coloured) part and it will be all fixed.

The dumb thing I did was Dremel the edge so I could get the bell crank to slide in easier - the actual fault was that the hole on the wing was not large enough and so the bearing was not able to rotate fully - seems silly now, but should be an easy fix.

Onto the bell crank hole covers now. It is a metal plate that the factory supply with small self taping screws to fit but Pete does his a different way and I decided to follow that route. So I have drilled out the holes and then tapped a thread into them. Also made the holes countersunk on the metal plate to accept countersunk head machine screws. It feels a little more permanent than the self tappers.

I also started on the Rudder. There is not too much I can do to it without the fuselage, but I have put the counterweight in place. This involves drilling a hole as shown in the photos - then pouring 100grams of resin and 250grams of lead shot into the front part of the rudder. I sealed up the hole afterwards with a carbon washer filed to a neat fit and flocked in place.

Finally I have decided to do what Pete does with the rear wing spar and reinforce on the inside as well as the outside. Imagine working blindfolded with wet spaghetti in a confined space that your arm just fits through and you will get a feeling for what this job was like. I just stayed as 'Zen' as possible and took my time - seemed to work out okay.

I still have to put some carbon tape on the root rib, plus reinforce the rear with glass tape and flock in the rear pin support - will most likely do those jobs this week as well as reinforce the seams on the rudder.

Bell crank bearing comes out at 90 degrees.

Bell crank hole cover with countersunk screw holes

Hole in rudder for counterweight

Lead shot and resin in the front of the rudder.

Hole covered with carbon washer and flocked in place.

Week 22 - Aileron horns and leading edge reinforcing

Hours to date: 237.5


Back in the groove now. 


Latest work has been on the Aileron horns which need reinforcing on each side with a carbon washer. Pete said this should be included in the kit but they were not in mine so to save time I made some out of the scrap Carbon sheet using the trusty 30mm hole saw. The 6mm bore then needed drilling out to 8mm to accept the Plastic bearings which push fit in each side.


Now I have resin again I was also able to complete the leading edge reinforce on the Starboard wing.


I also did something embarrassingly stupid with one of the bearings for the bell crank and wrecked it in the process. So it looks like I will have to remove it and put a new one in. Joy.

Strengthening on Aileron horn with Carbon washers

Starboard wing Leading Edge reinforce

Got some more fitting to do here as the pushrod still touches

Training Day 3

Rather than post about my own progress this week I decided to share some photos of Pete's Twister I took last weekend.


As you will see he does things a little different to the manual.


He builds the planes stronger than the manual says to. His planes do get maximum abuse as they are flown to the extreme of their envelope pretty much every day. Each of his Twisters does 350 hours a year, and a good bit of that 350 hours is aerobatics.


Onto the photos - and as you will see from the wing rib photo that his is in an even worse place than mine. He took so much rib off to fit the bell crank pushrod that a reinforcement behind the rib was needed. Sadly I did not take a photo of this but it consisted of 4 layers of glass, plus flock in the voids left in the honeycomb.


Quite a fiddle to get in behind the rib to do this job - arm through the flap counterweight hole - and you are effectively working blind.


You will also see that he does his fuel drain a different (better!) way - only drilling the holes that are needed right though the bottom wing skin and tank - unlike my method of making another smaller hole. Although this is what the manual tells you to do.


The other job I watched him do was fit a fuel level sender. This sender goes to a mechanical gauge and with the fuel flow meter on his Dynon that gives him two independent fuel readings.


My resin arrived yesterday so I will get cracking again this week.

And I thought my rib was in a bad place!

Fuel drain with holes drilled only for overflow and drain

Fuel sender

Support rib for rear wing pin - my next job

Nylon washers to space the controls into the right place

Week 20 - Starboard wing and revised paintjob

Hours to date 221.75


Pretty much up to speed with the Starboard wing now.

I've kind of ground to a halt as I've run out of resin. Yes the little bit that the factory give you with the kit is most certainly not enough to do the whole aircraft. Same goes for the fiberglass tape - the 40mm tape is running out now. Luckily Pete gave me some extra tape and I have just ordered some more resin so hopefully it will be all systems go again by next weekend.



The starboard wing does not seem to be made as well as the port one. Just little things here and there, but a more major thing cropped up when I drilled the hole for the bell crank and found the rib underneath to be in a different place to the port one. 

I made a paper template of the port wing section where it's bell crank hole was and the markings are in exactly the same place on the starboard wing - so it wasn't a case of it being marked up in the wrong place. Also the aileron when fitted has it's horn lining up perfectly with the hole which also leads me to think the rib was fitted in slightly the wrong place. We are only talking about 5mm here but it does make a difference.


Anyway it is not the end of the world and can be reinforced from the other side, but I must say it did worry me when I first saw it. Now I have filed it down a bit it seems to be not quite so bad as I originally thought. I will most likely be up at Pete's again this weekend for another training day and he has promised to show me how to fix it then. I will post again about this when it is done.

Starboard wing rib

Port wing is fine

In the meantime feast your eyes on the latest version of the paintjob. A bit more flowing now - not so many straight lines as before. Also there is now a chrome-like (think McLaren F1) strip that separates the black and orange. Should look quite funky when done.

Week 18 - Port wing

Hours to date: 195.0

Seeing the light at the end of the tunnel now with the Port wing.

Leading edge is now reinforced.

Root rib is glassed in and I did a bit of filling in with Micro balloons in the honeycomb in this rib plus on the flap and aileron counterweights. Also at the end of the Aileron there is a gap that needs to be filled with micro. The micro tends to be like working with slightly melted chocolate so after a while it runs into a nice smooth finish. I work it into any cavities with a wooden stirring stick - usually I cut one in half to have a finer edge to work with.

I also made up a couple of plywood washers that will go in the holes in the wings for the aileron bell cranks. I used a hole saw of 30mm diameter and that makes a 26mm diameter circle of plywood when cut out. The photo shows the plywood washer with plastic (nylon?) washer on top (black) and then the ali plate that will be screwed into the bottom of the wing - this will hold the aileron bell cranks in place and allows for future removal should that be needed.

The fuel drain is now finished except for putting in the metal fittings. Managed to get it pretty flush in the end. Also the fuel cap is looking quite decent now too - with just the cavity to fill in around the edge with filler to make that flush.

Next up I will be doing all these jobs to the Starboard wing so most likely won't be posting again for a while. 

Merry Christmas everyone and see you again in the new year.

Leading edge reinforced with 40mm glass and peel ply

Root rib - Micro in honeycomb and glass on edges

Micro in the gap at the end of the ailerons

Plywood washer for bell cranks

Fuel drain pretty much done - bar the fittings

Fuel cap - looking fairly decent - just needs filler now.

Electric Twister

A very interesting article from the USA about converting the Twister to electric flight.


What's different is the authors 'Range extender' device which overcomes most of the shortcomings of electric flight. 


This makes the Twister into a hybrid which I believe is the way forward until there is a leap in battery technology.


It sure would be nice and quiet flying a Twister this way, the only real noise would be from the prop.


http://blog.cafefoundation.org/?p=2520

Merry Christmas

Santa's upgrade from the sleigh.

Week 17 - More wing work

Hours to date 183.25


Cracking on with the Port wing now.


I had my inspector (Rex) round this week and he seemed pleased with my work so far.


To secure the bearings in the aileron bell cranks you need to use a centre punch which pushes out a little metal over the edge of the bearings. The distance from the edge is 1mm. I used a fine point punch first by hand to make a small dent in the right place. Then I switched to the medium size punch.


The next pic shows me just playing around with how the crank works - it will of course be on the inside of the wing when in place. I was just doing this to determine which crank goes in which wing.


Other work done this week: Fuel drain has been glassed over, flap counterweight arms are bonded in place and I have prepared the leading edge of the port wing for reinforcing - removed the peel ply, sanded down and flocked in any voids.


Finally there is a carbon washer that needs to be bonded onto the rear wing pin. The pin was put in place at the factory with their foam glue - which looks like it will be easy to remove but it is very strong and even the Dremel had a job to remove it. Got there in the end.


Just got to reinforce the root rib with glass, ditto the leading edge, then I will be close to finishing the Port wing. A few other little bits to do then I will switch back to the Starboard wing.

Centre punch around bearing to secure it.

Trying out the bell crank for function

Fuel drain glassed over

Flap counterweights bonded in

Leading edge prepped for reinforcing tape

Foam needs to be removed for CF washer on rear wing pin

Washer bonded in with Cotton Flock

Other hole cut out for the bell crank now too

Week 16 - Fuel drain

Hours to date 172.25


Moving right along to the bottom of the wing now and installing the fuel tank drain.


Pretty much the same deal as the fuel filler recess. Manual doesn't tell you anything - except where to drill. Hole size is 40mm for the outside and then I went quite a bit smaller inside - 25mm and then used the Dremel to elongate the hole where needed for the two drain holes. (see pic).


This is an easier job than the filler cap because of size and also access is a lot better - you can see underneath easily and work through the hole in the root end of the fuel tank. With the filler cap a little inspection mirror is needed.


After this job I installed the bearings in the Aileron bell cranks and drilled (Dremeled) the hole for one of the bell cranks. This hole will be covered in the end by a metal plate, but is necessary for installing the crank as both bearings that it will sit in are already installed inside the wing.


I may keep going with this one wing until it is done and then switch back to the other wing - we'll see.

Inner hole made a special shape to fit the drain holes

Drain plug installed - still have to glass in.

View from inside the tank

Hole for Aileron bell crank install.

Both bell cranks with bearings installed.

Drunk pilot

http://www.youtube.com/watch?v=0vH2yKfDq5Q&feature=share

Great skills and a great show. 

Week 15 - Fuel cap install

Total hours to date 164.25


I took the plunge and bonded in the fuel filler recess.


I'm glad I didn't try to do it the other night as there was quite a bit more prep work that I needed to do first. Basically sanding areas that need to bond with the flock and making sure the honeycomb is well out of the way so the flock will fill in the void in the wing skins. I did all this by hand as I find the Dremel a bit out of control for such a delicate task.


Before starting I laid in a polythene sheet inside the tank to catch any spills of flock or anything else that might fall in there.


I then spent quite a bit of time pushing flock into the space between the tank and the inside wing skin. This is the critical junction that has to be fuel tight when complete.


After that it was putting a heap of flock in the honeycomb void and on the cap recess itself.


All seemed to go okay.


A couple of nights later I put the reinforcing glass fabric over the outside which bonds the top outside edge of the recess with the wing. I used a Rotary cutter to cut out the fabric - it works a treat. Much better than scissors - especially when going round corners. I bought mine for less than £12 on eBay - I highly recommend you get one of these. I used a roll of duct tape to mark out the outer dimension and the fuel cap turned upside down to mark the inner hole - this worked out perfect.


Just gotta wait for everything to dry now and then I'll remove the black tape that was protecting the inner anodised area of the recess. To finish the job it will need sanding to make everything flush with the wing surface - I'll have to use a bit of filler here - which I don't have at the moment - so this job will be done much later.

Polythene sheet laid inside wing to protect tank

Lotsa flock

With perspex tool in place to hold at right height

With glass reinforcing in place

Rotary cutter - get one!

Week 15 - Fuel filler cap and Ailerons

Hours to date 160.5


Made some more progress with the fuel tanks this weekend.


I finally got hold of some hole saws and mandrels (the part that holds the hole saw and goes in the drill).


Unfortunately my drill only has a 10mm chuck and the larger mandrel was much bigger than this so I had to spend about 2 hours turning this down so it fitted in my chuck. As I don't have a lathe this was a slow job with a coarse file and then the Dremel to finish.


Before I drilled anything I did a 'gross error check' by turning all the lights off in the garage and shining a very bright LED lamp underneath the wing and also one inside the fuel tank from the root end and this allowed me to see where the markings were that I had made. The copper tape on the tanks shows up as an indicator very well using this method.


It is okay to be paranoid about screwing this job up as you are drilling close to the main spar and I just had to see for myself that I hadn't made a gross error as there is no going back with this job.


Using the hole saws set your drill to the slowest speed. I made a small pilot hole first of 2mm after measuring many times! (note the number of markings I made). Then a 6mm hole all the way through and only then did I use the hole saw. I couldn't get hold of a 88mm one so had to use an 86 and then carefully Dremel out the extra 2mm all round afterwards.


The first larger hole must only be drilled down through the top layer of the wing skin - as soon as you hit the honeycomb stop. (see pic).


Then change to the smaller 75mm hole saw and this time cut all the way through including into the tank itself.


Now clean out the honeycomb that is left between the smaller and larger holes.


Take care to line up the fuel cap with the airstream and mark the metal recess part up so it's bonded in the right place.


Pete has lent me a tool he made up out of perspex which helps the cap be bonded flush to the wing surface (see photo).


I got to this point and then wimped out! Decided it was the end of a long day and I would leave the bonding in till another day when I am up for it.


The rest of the day I was making up some little carbon ribs for the ends of the ailerons. These are not supplied as part of the kit and Pete had said to put a piece of styrofoam in there and then glass over but I decided to make these out of the thin carbon that was left over from all the other parts. They only weigh less than 3 grams each so shouldn't be a weight problem, plus they won't need glassing over - just flocking in the gaps and edges should do the trick.


The final photo shows the technique for fitting the control surfaces - use a piece of sandpaper down the gaps and slide it back and forth until the control surface moves freely without binding or rubbing on anything. Note the sandpaper should be used on the wing and not on the control surface as that is thin and you will soon go through it.


Hopefully in the next post I will be talking about having successfully bonded in the fuel cap.

Outer hole - stop drilling at this point

Inner hole cut right through

Lining up the fuel cap parallel to the airstream

'Scarf' 20mm round the edge for glassing to come later

Perspex tool to hold cap flush with wing

Aileron end - instructions do not say to do any more

Left over carbon from other parts

Carbon rib

Sandpaper in wing method to fit surfaces