Week 149 - Pitot tube

Hours to date: 1327.25

A fairly good couple of weeks progress has been made. The Port wing is now up to speed. 

A minor setback - the rear pin bearing (and therefore the factory drilled hole) were not in the right place. Only out by about 3mm. Matthias is sending me a new bearing so I'll get this fixed soon.

I've even started on the pitot tube.

A reasonably straight forward job this one.

Bond the end pieces into the tube (with runny flock).

Drill a 16mm hole into the leading edge - where it lines up with the outboard end of the Aileron.

Then using a long drill bit (more than 250mm) to drill through the main spar (!).

The tube has to be angled down by 2 degrees. This put me off a bit as I was so worried about getting it angled down I ended up drilling the hole in the spar a little too high. Then I had to enlarge the hole in the leading edge until the tube was at 2 degrees.

If I could do the job again I would ignore the 2 degrees bit while drilling and just drill in the middle of the spar. Then afterwards I would just enlarge the hole in the leading edge at the bottom until 2 degrees is achieved. 

Anyway - it's nothing a little flock won't fix!

Next up will be fixing the Tygon tube to the rear of the main spar. This will be done with the U shaped fiberglass brackets (same as I made up for the rudder cable guide tubes).

You can see below the new tool I bought for this job - a long handled 'grabber'. I should have bought this ages ago - it's going to come in very handy I think.

I've finished the last of the composite screws too on the fuel system (for the time being anyway - until the engine is on).

Next job will most likely be the canopy.

Rear wing pin bearing is out - by about 3mm

Pitot - inline with aileron outboard edge

Long drill to get through main spar

Pitot tube before bonding in end pieces (it's the retractable type)

2 degrees

Establishing Zero degrees

Lockwire on pitot end fittings - I had to use a 5 to 6mm adapter for the tube

Hole needs to be fixed with flock

Long 'Grabber'

Another composite screw with P-clips for the Port fuel lines

More composite screws and P-clips for the oil cooler lines

Ditto for the fuel lines on the firewall back

 

Safety Cell article

Another poorly researched article - this time from LOOP.

It makes the safety cell idea sound like some kind of brand new innovation.

The Twister has had it for over 10 years now.

The Twister is truly a plane ahead of its time.

Click on the images for a bigger view.

Week 147 - Fuel System cont. 5

Hours to date: 1307.5

A quick update.

I had a much better second attempt with the fuel probe, after buying a proper pipe bending tool (which is pretty cheap at under £10). It made the job so much easier.

A slight complication as the metal plate on the back now fouls with the O-ring sealing ridge on the tank. Will have to consult Pete to see how he solved this problem.

I cleaned out all my fuel hoses too. Some with the safety wire and cloth dipped in Acetone technique. The others, with the quick release fittings do not allow this technique so I just poured fuel through them (from one Jerry can to another).

Of course if you are smarter than me you would have done all this before putting the hose fittings on :)

I finally got the hose guides fitted and am happy to report that they work really well.

The fine filter is now mounted and I've only got a few more composite screws to do and things will be pretty much done on the fuse regarding the fuel system.

I've swapped over the wings and will now bring the Port wing up to speed with the same jobs - so I most likely won't do a post for 2 weeks or so while that happens.

Cloth (dipped in Acetone) on safety wire technique for cleaning hoses.

Pipe bending tool - just trying it out here on the wrecked fuel probe.

2nd attempt at fuel probe - much better result!

Fuel probe end - inner copper wire must be separated from ali tube. Done with plastic 'squares' supplied.

Hose guide mounts in place - ready for their P-clips and flared tubes.

With P-clips and flared tubes in place - works well.

Port side

Fuel system overview

Fuel flow senders getting sorted with mounts.

Swapped the wings over.

Week 146 - Fuel System cont. 4

Hours to date: 1294.75

Good news is that one wing is pretty much done regarding the fuel system.

Bad news is that I totally screwed up the fuel sender probe job - so it looks like I'll have to order a new one of those. The tube did not bend very easily at all and I ended up cracking the pipe open :(

I bonded in the fuel vent line - a fairly easy job - although you are working blind as it's inside the tank. I put a machine screw in the tube end (after wrapping it in duct tape and covering it with release wax) to stop any flock going in there. The manual warns against this so I was a bit paranoid about that happening.

The thread sealant and metal braided hose arrived so I was able to complete the fuel flow transducer installation for both lines.

I also put thread sealant on the fuel pressure sender - which is screwed into the end of the banjo bolt on the fine fuel filter. 

I've also figured out that I can put a wing on by myself. This is a great help as I was able to do the return line bulkhead fitting into the tank and also make up the hose for the feed line.

Finally the composite screws have arrived too so I've installed the fine filter mount at long last. 

I made up some composite screws to the correct length for the flared tube mounts too. I just bought some machine screws and cut them to the right length then screwed them into these special composite screw mounts that have a threaded flange at the base. I used Loctite retaining fluid to secure them in place. Bonding those on the spar tunnel will be the next job I think.

It may be a boring couple of weeks after that as I will most likely do all the jobs that I've done on the starboard wing to the port wing.

Flop tube easily clears vent line.

Coat hanger wire mock up of fuel probe bends

Vent line end with screw in end to stop flock going in

New toy! Right angle attachment for the mighty Dremel

Thread sealant - this stuff is the business

Bit of a mess of hoses here until I get them sorted with composite screw mounts

Both fuel flow senders in place with hoses

New route for the oil cooler hoses - to the left

This is as far as I could get the wing on by myself

Getting me wing on!

Fuel feed line complete now with braided hose to tank

Return line bulkhead fitting now bonded in

Composite screws made up for the spar tunnel (hose guide flared tube mounts)

Bonding in the fine filter mount composite screws

Ditto

Week 145 - Fuel System cont. 3

Hours to date: 1285.25

Well this fuel system seems to be taking longer than I thought. I don't mind spending lots of time on it though as it has to be right.

I bought some fuel flow transducers (£170 each!) as I really do want to know the fuel flow rate. Two are required as the UL power is fuel injected so has a feed line and a return line. The system pumps through a lot more fuel than is actually used by the engine (up to 100 litres an hour) so the Dynon uses the data from both transducers to determine actual fuel usage.

I've already fitted the return line one as you'll see below.

The feed one is not fitted yet as I'm still waiting on my steel braided hose to arrive.

Before I fit the adapters to the transducers finally I will apply some thread sealant. I've just ordered this so will get that done next weekend.

Below you will see my solution for guiding the hoses close to their exit point in the fuselage to wing root.

The flared tube is made of anodised aluminium and weights nothing - also it is the perfect surface for the nylon hose to smoothly run through with no wear (not that the hose will move much in there once the wings are on).

The flared tube is then held in place by a P-clip (which is attached to the spar tunnel via a composite screw - again this part is still to arrive).

The flared tube part in case you're wondering is actually called - wait for it - a Flesh Tunnel. What some people think is a good idea is putting these things in their ear lobes! Don't think I'll be doing that any time soon.

Little did the jewellery people selling me these tubes know that they would end up in an aircraft...

As you'll see below I tried to do both tubes/hoses with one composite screw - but this was too much of a compromise for both hoses need to be in just the right place - so I'll use two composite screws here.

I've applied some 'Cool-it' tape to the cell and fuse where the oil cooler will sit. I don't want the heat from that coming into the cockpit too much.

The new 'Cool-it' tubes arrived too so I was able to fit those to the oil cooler hoses and figure out where everything is going to go. After a bit of research it looks like I will be okay to get the fittings for these through the firewall after all, but I won't do any of this until the engine and other components on the firewall are in place.

Onto a real fiddle of a job. Bonding in the fuel overflow/vent line. Access is quite limited through the fuel tank access hole plus the flop tube is now in there and gets in the way a bit. Anyway I got the area roughed up and bonded it in with flock and one layer of glass. I built a special block of wood to hold the hose in place while it sets and wrapped the flop tube in a plastic bag so it didn't get any flock on it.

I'm going to bond in the other end - up by the fuel filler hole - next.

Finally, I'm now reading up on how to install the fuel probes that will go in each tank. I previously bought some pipe bending tools so that will come in handy - you only get one go at bending this tube so lots of thought has to be done beforehand.

More on that next week...

'Red cubes' fuel flow transducers

With adapters and fittings on.

Position of feed line transducer

'Flesh Tunnel' flared tube for guiding the hoses.

Return line transducer in place.

Front view - composite screws to mount the transducers still to come.

Hose guides - first attempt. Not successful using only one composite screw

Hose guide on other side. Getting position sorted.

'Cool-it' tape applied to oil cooler area

Oil Cooler with 'Cool-it' tube on the hoses.

Roughing up the area for the vent line bonding

Wood block I made for holding down the vent line while it bonds

Wood block doing it's job. 12" Spanner is for weighting it down while it sets

Fuel probe and bending tool.