Smoke art

Reinforcing wing ribs and finishing Aileron hinge pins

Yesterday was spent finishing off the Aileron hinge pins which involved filing down the excess flock so it was flush with the edge of the aileron and then adding a reinforcing of 40mm fiberglass tape.

To do the tape part of this job in such a confined area it was best to wet out the tape completely first - I did this by dipping it in the cup of resin and then squeezing out the excess resin. Then fold it in half and insert. I used a stirring stick cut in half to press down the tape at the back. I also throughly wet out the area inside first.

A good inspection lamp is vital for these types of jobs - to see down into a dark confined space - I have a LED lamp which is very bright and cordless so pretty good for the job.

Most of the day was spent reinforcing the ribs on the trailing edge of the wings. Again 40mm tape is used.

Next up I think I will cut the holes for the counterweights in the wings and also bond the flap support to the rib.

Both aileron hinge pins finished with flock and finally a layer of 40mm tape

Reinforced ribs with tape

Ditto

RC Model Twister

http://www.seagullmodels.com/ProductDetail.asp?id=118

Aileron hinge pins

Onto the ailerons now.

Same deal as the elevator hinge pins - they must be completely surrounded by Flock.

First off I tried to do the whole job in one go - but this turned out to be a mess. The Flock is a bit gooey and tends to ooze out everywhere.

Figured out that I should do it in two parts.

This worked out well. It has the added benefit of being able to see the hinge pin and line it up exactly. (if it were immersed in the flock then this would be more difficult.)

I also prepped the wings rear rib for fiberglass taping by putting a smooth radius on the edges with flock.

A job of two halves

Make sure to roughen up hinge pin so it bonds to the flock

Clamping everything down so it doesn't move about

Another clamp to hold the pin in correct place whilst it dries

Back of wings before flock radius

After radius with flock

Both wings prepped with flock

Elevator work

Another decent stint of 9.5 hours this weekend.

Worked mainly on the elevators, job was made much harder as I had to remove a hinge pin that had been put in already in the factory (this is not normal). It took ages, but had to be done as it was in the wrong position (out by 3 mm) and was also put in with Micro (which is non-structural). So I had to remove that first and grind out the micro. This added about 3 hours to the job.

The hinge pins are put in with lots of Cotton Flock/Resin mix. (Flock is structural)

The next day I installed the bearings in the Horizontal Stabilizer that the hinge pins go into when completed.

The instructions say the bearings should be "sanded slightly" to fit - as you can see quite a bit of the outer plastic has to be taken off - I used a file. You also need to take all the 'meat' out of the horz stab where the hinge will go for it to fit - leaving just the outer layer of carbon/glass.

The bearing is pushed onto the hinge pin and then bonded with 5 minute resin in place. A 2mm gap at the end and lining everything up nicely with the trailing edge of the elevator and horz stab. After this sets the elevator is removed and all the space around the bearing is filled with Flock.

I also did 3 hours during the week and finished off the control rods.

Elevator bearing before

Bearing after. Quite a bit of the outer has to be taken off.

Hinge pin bonded into elevator end with Flock

Bearing is slid on the pin and bonded with 5 minute resin

Bearing bonded in place

All voids filled with Flock

There's a reason it's called the Twister

Cutting holes in stuff

Did a decent stint yesterday, 8 hours.

I cut out the holes in the flaps and ailerons for the mass balance arms.

As you can see from the photos the factory marked hole was a little too large on the flaps, the ailerons were spot on.

The Dremel made light work of cutting the holes, which I left about 2mm small and fine tuned with a file till the arm was a neat fit.

The arms have to have a slot cut in the honeycomb. This is filled with micro when getting bonded into the control surface inner later on.

I also cut down the lead weights for each mass balance. 4 in all. Bit of a slow and messy job - took me a while to get a feel for how much to take off. Anyway got there in the end and they are both within a gram or two of each other - I have left them at the heavy end of the tolerance for the time being until figuring out exactly what they need to be later on. (easier to take weight off than put it on).

I also cut out the rudder where the hinges will go and spent some more time on the tailplane with fitting the bearings for the elevators - more on that job later.

Factory markings for hole in flap

My markings- less width same depth

The mighty Dremel is built for such a job

Arm fits pretty good.

Inside - where the slot will be bonded with micro

Inside

Mass balance weights for Flaps and Ailerons

Mass balance arms cut to length and slots made in end

Rudder with slots cut out for hinges.

Control rods

I actually did some work on the kit last night. I think that's 2 full weeks without any progress. (obviously not happy about that!)

Last night I did some more reinforcing of the seams on the control rods.

As promised I would talk about the fiberglass 'tape' used on this job.

It is very hard to wet out properly. I figured out that trying to do the whole length in one go is harder than doing it in sections. Still use one piece of tape - just wet out one half first then do the next half. I found this quite a bit easier to manage and got a much better result - straighter tape and better wetted out.

Bit of a messy job this as the resin tends to run down around the rod and you end up with quite a bit of resin below where it is needed as it forms like paint runs underneath. Use your gloved hands to wipe this off at the end and minimize the excess resin.

As you can see from the below images the tape comes in a roll and is a certain width - but before applying its best to pull it outwards. Doing this first while it is dry before applying is easier than when it is wet.

The last photo is a top tip I got from a book - wrap your resin weighing scales in plastic - so that they don't get covered in resin if you spill some (resin is always mixed by weight rather than volume). I have taken it a bit further and put the whole thing in an old upturned plastic container lid so that if the resin ever spills over completely then the whole mess is contained in the lid.

Elevator and two aileron control rods

tape laminated on seams

Fiberglass 'Tape' - in this case 40mm width

Pull it apart gently while dry

Scales in plastic and then in a tray to catch any spills

Sywell Rally

On Saturday I visited the LAA Rally at Sywell.

I was surprised not to see any Silence Twisters there. Lots of other interesting aircraft though - with the highlight for me being the Mew Gull. A single-seater taildragger with amazing performance (faster than a Hurricane at sea-level) but poor visibility from that cockpit and what seems to me to be quite small tail surfaces. The tailplane seemed about half the surface area of the Twister (and this thing has 205hp)

Also there was an RV-8 that was painted orange (flat rather than metallic) even the cockpit was orange! (and I thought I liked orange).

Mew Gull

RV-8 - agent orange

Smokin!

Flying machine

Well it does have a couple of wings and is blindingly quick but if it leaves the ground then it's all gone wrong.

As you can see Belgium was wet (and cold) but the racing was good. I'm still recovering, will post something new when I do some more work on the plane next week.

Michael Schumacher on the Kemmel Straight

Fuel tanks

Did some work to the fuel tanks over the weekend and finished them last night.

First part of the job is putting copper tape in a grid pattern around the whole tank.

I found the best technique with the tape was to pull quite hard on it (towards you) with one hand while sticking down with the other hand. This way you avoid any air bubbles or wrinkles forming in the tape. Works well going round the corners too.

After that you have to solder all the joins otherwise the sticky part of the tape would not make a good contact with the section of tape underneath it. Be careful with the soldering iron not to burn a hole in your tank. I found it better to make a connection quickly then go back and tidy the solder up with the iron afterwards.

You don't want the solder sitting up too much as the tank needs to bond into the wing later and a mound of solder would make a void between the tank and wing.

Finally an earthing wire must be connected to the grid. This will be connected to the earth on the engine mount much later on.

The other work I did over the weekend was taking some more peel ply off the flaps and rudder plus bonding some 40mm fiberglass to one of the aileron control pushrods (more about that later).

I won't be posting again for a week or so as I am off to Belgium for the Formula One Grand Prix at Spa this weekend.

One tank and the panel of parts for both tanks

Make lots of pencil marks for the tape and make sure to avoid the fuel cap area

One tank taped with copper

All joins soldered and the earthing wire in place ready to be joined

Both tanks done

Peel ply removed from both flaps and rudder

Aileron control pushrod bonded with fiberglass tape