Wednesday, 29 May 2013

Week 93 - Battery box, Elevator guides and Confor foam

Hours to date: 943.0

Haven't got a great deal done in the last 2 weeks. Been sick with the flu and then had my brother staying last weekend.

Anyway things are progressing with the battery tray/box as you will see below.

After cutting the hole, I wrapped the wooden mockup of the battery with Duct tape and made it slightly bigger all round first with a layer of cardboard. This is to allow for the layers of carbon on the inside and for some foam that I will use to make the battery sit firmly in place and not be subject to vibration.

I used 4 layers of Carbon on the outside.

Once that was done I roughed up the surrounding area on the inside and put another 2 layers of Carbon on there. Overlapping and increasing the strength.

This may sound like overkill but the 7kg battery will weight as much as 42kg when pulling 6g.

I'm going for a double redundancy with the securing of it too.

Next job is to make a cover (again out of Carbon) that will be bolted through the cell on its flanges (4 bolts.)

Then I will put a securing strap over made out of nylon webbing as a backup.

As you can see below the Flap drive box needs the wire extending to reach the cockpit control. The wire that would do that is not included in the kit. It's easy enough to do with some butt splices.

I've also started working on the elevator push rod guides.

These will be mounted in the bottom of the safety cell. Pete is going to lend me a mould for the rear one as the safety cell is not perpendicular to the base at the end. As you can see the nylon bearings would rub against the carbon bracket they are mounted on - so I Dremeled out grooves for them to run in.

Finally the last photo shows the Confor foam I bought which will be stitched into the bottom part of the seat cover.

It is the best way of protecting your spine in an accident. Unlike a car an accident in a plane will often result in the main force being downwards and it is your spine that suffers. Belts are really only good for resisting horizontal force. And negative g :)

A bit pricey as I went for the Duo version with two grades of foam - £67. But well worth it for the safety and comfort factor.

The memory foam in it should make long flights in the Twister more comfortable.

Battery will sit like this - under baggage shelf

Grinding out grooves for the nylon rollers in the elevator guides

They rotate freely now

Extending the flap drive wires

Battery mock up in place - ready for lay up

Weighing down the fuselage lower to make sure the battery box fits.

All done on the underside with 4 layers of Carbon

Inside roughed up ready for 2 more layers of Carbon

Confor foam Duo

Tuesday, 14 May 2013

Week 91 - Flaps, Battery box, Baggage tray

Hours to date: 928.25

The flaps are now done. I've even drilled the drain holes in the root end tips.


Much later on I will mount them on the wings and then finally fit them to the flap actuators.

Onto the battery.

I've settled on a Varley Red Top 25 - which is a gas recombinant type - same as the Odyssey series from the USA.

The Varley is used in RAF aircraft so it must be top quality.

The UL Power manual states a minimum of an 18 amp hour battery and the Varley 25 is rated at 20 amp hour so it fits the bill nicely.

It's also more compact than an Odyssey, which is just as well because as you can see below I want it to remain under the baggage shelf.

Pete has his mounted vertically and it protrudes out into the baggage area.

I've made a wooden mock up of the battery to the exact same size. I'll use this as a mould to make a mounting tray later on.

I got up early on Sunday and spent 4 hours working on the electrics too.

I figured out what all the fuses should be and I've also got a nice little system with the Avionics having a separate bus so they can be switched separately to the rest of the kit.

I modified the GPS power cable so that it will connect directly into my Avionics bus rather than use a cigarette lighter socket.

And finally I modified the Infinity stick grip to move the radio push-to-talk to the top left button. It was in the trigger position which was much too easy to push by mistake. I'll cover the trigger hole later.

Carbon washers in and top rib flocked and glassed in.

Counterweights attached to arms

All done - including micro in the end gap and drain holes drilled.

Baggage shelf - rough fitting.

Battery mockup in wood - showing where it will go.

Friday, 10 May 2013

Living Legend - Ken Wallis

I went to a brilliant talk by the great Ken Wallis last night.

His brain is still very sharp - despite being 97.

He still flys his Autogyros often too - he has 16 of them.

His main claim to fame is doing all the flying of 'Little Nellie' his Autogyro in the James Bond movie You Only Live Twice.

But there is so much more to this man.

Designer, engineer, bomber pilot, model maker, test pilot and more.

It was a privilege to hear him speak.

Ken Wallis


Tuesday, 7 May 2013

Week 90 - Flaps and remote units tray

Hours to date: 914.25

I didn't make much progress last week - far too busy at work with late nights - then a hangover on the following weekend which slowed me down!

Last weekend was a Bank holiday so I made up for it by putting in 3 good days.

Passing 900 hours...

I feel like I might be over halfway now. That light at the end of the tunnel is a small pin prick - just visible for the first time.

I managed to kill my Dremel as well. Dead Dremel.

Will have to get another one soon. I don't know how you would build a Twister without one.

I was pretty chuffed to see that my alignment of the EFIS was spot on with relation to the wings level attitude (see photo below).

As discussed before that attitude is not adjustable by the EFIS so must be set by the panel position. Same goes for Yaw which is also spot on.

The other angle-critical install was the remote compass for the EFIS - which has to be within 1 degree of Pitch, Roll and Yaw of the EFIS to give an accurate reading.

I am confident I got the Pitch and Roll spot on - confirmed by use of the protractor spirit level (for pitch) and a standard spirit level (for roll).

The Yaw I feel is just a touch out so I will correct this by slightly filling out the holes on the remote compass (forward on one side and back on the other) to shift it to be spot on. The only real way of knowing it is perfect will be to cross check it with the GPS. Something to be done much later on when the plane is outdoors and the GPS has a good signal.

The 'steam' gauge mechanical compass will also be a useful cross check, although not as accurate as the GPS methinks.

For the Radio and Transponder TRIG make a very compact and light unit for the panel itself, then a larger unit with all the guts in it. This has to be mounted somewhere so I have made up a shelf the will go behind the panel and hang off the inside top of the cell.

Some more parts for the electrics arrived too. The brass plates with lots of tabs on it will be the main ground bus. Mounted on either side of the firewall with two large brass bolts connecting them electrically and mechanically.

The battery negative wire will be attached to this large bolt on the non-firewall side. I'm going to use the other bolt on the other side to run a large wire back to my fuse box/main power bus. There are 12 grounds on the fusebox/bus that can be used locally to save on wire and mess.

I also bought a cigarette lighter socket that will power the iPad mini I intend to have on my left knee. The iPad mini will be used for weather, charts and as a backup for navigation (if the GPS dies).

Finally I got around to doing the wing root ends of the flaps.

This all has to be millimetre perfect as the pins will have to line up and fit into the flap actuators (when they are mounted in the wing root).

As you can see I used the flap actuators themselves to make sure the pins line up as the flock sets.

Next little job on that to finish it off is flocking then glassing in the edges of the upper root rib and adding carbon washers over the pins (flocking those in too).

As you can see the pins are comfortably long enough - I figured that the pins can always be made shorter but there is no way to make them longer once they are in.


EFIS is level when wings are - result!

Main ground bus with 'forest' of grounds - tabs

iPad mini power socket

Remote compass mounting

Shelf for Transponder and Radio remote units

Will go about here.

Flap pins plenty long enough.

A little bit needs grinding out where the flap actuator goes.

Actuators on the pins while the flock sets.