Monday, 26 August 2013

Week 106 - Throttle & Brake assembly, Avionics tray & Parking Brake

Hours to date: 1088.5

I've had 3 good days on the Twister.

Got the throttle assembly done.

Pretty straight forward. Just remember to rough up the top of the Ali plate (that will get bonded to the underside of the cell) before bolting everything together.

I was missing a washer - and I'm not sure if it is some special type (Nylon?) so will ask about that at the factory before bonding the assembly in place.

I have to say that just bonding this plate on with flock does not seem enough to me - I am thinking about backing this up with a couple of bolts through the cell and plate. I'll talk to Pete about this as he used to have this type of throttle before changing to a vernier type.

Onto the parking brake.

Due to my oil cooler mod I am locating the parking brake on the same side as the throttle. (The manual says to put it on the starboard side.)

I noticed that some of the very early kits had the parking brake on the port side and I've done a few trial runs to see if it is an ergonomic nightmare or not. Thankfully it's not.

The only further addition to this assembly is to make a plate over the plywood blocks and brake to hold it securely in place. 

The manual says just to use plywood blocks either side to stop it twisting when you turn the knob. But this means that only a small screw is holding the whole lower assembly in place. I don't think this is enough. Especially as the parking brake assembly weighs quite a bit and when pulling 6G will be a significant load.

I plan to lay up a carbon plate over this (probably 4 or 5 layers) then screw this to the plywood blocks with self tappers.

The other thing I've been working on is installing the tray I made earlier for the Trig Radio and Transponder remote units.

Pretty straight forward - just had to make sure it was being located in a place to miss the back of the EFIS unit.

I bonded it in with lots of flock and 2 layers of carbon on each side - overlapping the flanges.

Again this is a significant weight (just under 1kg) so has to be secure. I may even put some bolts through the flanges and out to the top of the cell for security - we'll see.

I've put some more micro on the rudder control stops - will post a photo of that next time.

Start off with a pile of bits...

And a few hours later you should see this

Lower view - Nothing tightened up yet

Throttle assembly test fit.

Parking brake assembly

Location of parking brake (right)

Underside of cell with brake assembly

Bonding in the plywood blocks - blue tac is to hold it in place while it sets

Trig radio and transponder remote units in tray

Upside down view of bonding in the tray (right way up like here once bonded)

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.

Plasticine to determine rudder control stops

Control stops done.

Control stop - top view

Setting the horz stab bearing - again!

Lines up this time!

Wednesday, 21 August 2013

Holy Cowl!

It seems that for every UL Power engine installation there is a different take on the cowling.

This one is from the Czech-Republic and I think it is on a Bristell NG-5.

Not sure what the NACA duct is on the Port side? Perhaps for an oil cooler.

The lower exit section looks like an afterthought. I wonder if it is fixed or movable like a cowl flap?

Monday, 19 August 2013

Flying Legends

I visited Duxford last month for a great day out.

The Flying Legends airshow. Known as the best warbird airshow in the world.

It lived up to expectations.

Here is a short video of what I saw.

Thursday, 8 August 2013

License revalidated

There is a reason for my lack of progress lately.

I've been doing a bit of flying - to revalidate my license.

I was pretty rusty - having not flown as PIC for 2.5 years.

I also had to convert it to an EASA type - lots of forms and quite a bit of money - for another piece of paper that looks almost the same as the one I already have...

So now I've finally got a Cessna 172 in my log book.

Tuesday, 6 August 2013

Week 103 - Tailwheel mudguards and engine mount

Hours to date: 1058.25

As you will see below the Twister finally got to sit on it's tailwheel for the first time.

I've been clamping the shroud from the sides every now and then and leaving it overnight - it seems to be a much better shape now - fits the rudder much closer. I think I will put some carbon down the inside and clamp the lot together to make it take on the absolute correct shape.

I made up some mudguards - a curved one for the front. Made out of a glass sandwich (Nomex). Fits nicely and I glassed that in.

Inside the rudder I used a rib sent by the factory - but it was straight - so it did not make it all the way to the end of the rudder. I've made a curved section and glassed that in too. 

While I had the tail outside and had the space at the firewall I decided to trial fit the engine mount.

Well as you can see three of the holes fit okay but the fourth one is a little out. By about 6mm. I haven't asked Pete how to fix this yet but I am guessing it will be along the lines of - Flock in the hole then drill out a new one. I'll share his advice when I get it.

I managed to get the starboard elevator hex out without destroying it.

It will need a little bit of carbon on it but is otherwise intact. Fixing this back in the right place will have to wait until I can get access to a work area that allows me to leave both tailplanes on for 24 hours (so the flock can set).

I've also taken the decision to re-do both securing pins and front bearings for both tailplanes. I made a screw up with alignment and I am just not happy with them. The Port one is only out by the tiniest amount but I will still redo both sides as they must be perfect.

My mistake was to get too fixated on the pin itself - that job required a bit of thought. In doing so I failed to realise that the alignment was not perfect at the time and blindly went ahead and bonded in the front bearings. Not good.

I think the right way to do it is to align the elevator in the neutral position at the outboard end with a clamp. Then move the tailplane up or down until the root end of the elevator trailing edge lines up with the root end of the fuselage trailing edge.

So just when I thought I was getting done with the tail - there's more work to do! My fault entirely and I have learned a lesson because of it.

I've still got to add some tailwheel 'stops' that will limit the rudder travel to the factory specs. 190mm + or - 15mm either side. Measured at 400mm from pivot point. These will just be carbon blocks bonded on the front mudguard.

Sitting on it's tailwheel for the first time.

Shroud starting to fit better to the rudder

Engine mount trial fit

One hole is out...

Tailwheel front mudguard

Getting the hex out of the starboard elevator

Rudder mudguard - straight section then curved section added.

Front mudguard glassed in


Hex removed

Thursday, 1 August 2013

French Twister takes to the air

The first Twister built in France has taken it's maiden flight.

Same spec as mine - Integrated tailwheel, fixed gear with UL260iSA power.

I will be interested to hear what performance figures they get - once everything has settled down and the engine is run in.