Ch 21 Strakes – Fuel/Baggage

Finalise the Vents

Date:  12-13-2023
Number of Hours:  8
Manual Reference:  21

These vents have been an ongoing issue. I guess I could or should have done them in plastic pipes and it would have been soooo much easier. I had to do it in large diameter fuel line aluminum didn’t I?

I wanted the big bore so that the two tanks could equalise quickly via the common sump and I wanted no leaks or smell in the cockpit.

Given I have so little room in this plane these lines have come in and out several times. Of course being pretty solid I now have to ensure they don’t move and are firmly fixed.

After some work these are getting pretty close. I made fixing points but I now find some of them aren’t necessary.

With the coolant motors now in one of the vents wasn’t going to fit. I made another hole in the bottom of the plane forward of the previous one and of course then the bottom piece wouldn’t fit.

Out came one of these strange shapes for a 1.5″ trim to make it work. Its lots of fun getting these things in and out.

Now we have a fit.

A LOT of thinking went into how to mount the pipes so they are secure. In the end I came up with this strange bracket that gets foxed to the undercarriage bow.

It was a little tricky getting this to work.

Here we are floxed in place and cured. The pipes are now very solid. You can see I’ve trimmed them as well. I have made it low pressure at the back and I think this might be wrong,  I might slant the other way for positive pressure into the tanks. I’ve left enough room for the option.

I could argue for both cases. Maybe too much ram pressure would cause fuel to be shunted overboard when the tanks are very full at some angles? Maybe the negative pressure would suck some fuel out? In both cases the fuel would have to climb to the top of the rollover after filling the vent bottle before it traveled downhill to the underside vents. I can’t see it happening, but I’ve been wrong before.

Here we are again, all solid. I’ve used P-clamps and a few quality cable ties. The last bit is the line to the right side of the sump. I will sort that out when the fuel line is done and do them both together.

I put the ECU’s back in for now and can see that once wired up, a few hose clamps will neaten up and secure all those wires.

 

Fuel Gauges 4 (Update)

Date:  09-20-2022
Number of Hours:  15
Manual Reference:  no ref

Its four years since I updated the fuel gauges. While waiting for the engine and with the lighting now in place, that area next to the gauges was pretty ugly.

It was a fair bit of work to dig out some room for these led strips and then secure the wires. Now you can see all that light spilling out the sides?

Here’s the other side at the front. It was the same problem in the back seat area. At night all that side light might be an issue.

I’ve opted for some very thin aluminium shields which I’ve now painted and made nice. I was going to use plastic and have that same plastic engraved with the fuel level positions in liters. Given I am waiting on the engine still, I decided to do this work now and I can just use stickers for the fuel levels later. This will be much easier to get right as I can start with some hand written labels.

All installed in the back seat area. I would have liked a seamless transition rather than a stick on plate. Maybe I’ll pretty it up later. This is a functional result and not too bad.

The red looks nice? Its all ‘dimmable’ of course.

All done for now. Plenty of these little jobs at the moment.

Fuel Cap Install, Safety Line and Earth

Date:  09-29-2021
Number of Hours:  25
Manual Reference:  21

Now the strakes are beautifully painted I need to cut two big holes in them for the fuel caps.

The exact position for the fuel caps just took too long. When I built the strakes I made plastic templates so I would know where the flanges were to allow the caps to go close but not on top.This is for strength.

I used the tennis ball to help visualise what would happen if I spilled fuel. I wanted to gauge the runoff and its direction relative to the caps.

I didn’t want to be too near the passenger and right in the middle of the highest point would give me maximum fuel if I ever wanted every drop possible. The downside of this was it put the caps too far from the leading edge to be comfortable when juggling a heavy fuel nozzle. It also had me or a refueler leaning well over my nice pretty paint with rivets in jeans scratching my while plane. Hey!!

I ended up going on the ‘down slope’ after calculating how much less fuel I would carry if the caps were in a sensible position. The answer was less than a liter fewer a side.

Marking this out after measuring and remeasuring and second guessing myself over a few days was a big deal.

Once I had a tiny hole marked it was on! This first hole took ages, the second one happened in about 20 minutes.

I used lots of toys including the improvised sanding drum aka red tape with sandpaper glued to it.

You can see I have just gone down to the inner skin at the bottom. At the sides I have removed material so I can get flox under the top skin. When that bonds to the fuel cap to will give extra strength to hold the cap in place.

I made a bunch of key holes via a round bit to give the flox something to grab onto. I also roughed out the cap bottom with 80 grit after this photo. I took the shine off the key surface paint as well.

Then I had to cut through the hole to the tank itself. I had my vacuum cleaner on hand and if any debris got in the tank it is too small to see. I will be flushing fuel though them later when I do W&B.

Given I am not exactly to plans on this I want to weigh with different fuel loads when I have the aircraft scales hired.  That’s when the fuel calibration will be done.

I used a lot of flox and cleaned up a good squeeze out. I think there are no voids to worry about. I used the same epoxy the tanks were built with. Old school and proven fuel safe over many years.

The fuel caps are now permanently in place.

A very important safety item is to ensure the caps do not depart the airplane if they are not locked in place.

Of course I will never forget this but I’d hate to have even the possibility of a cap go into the prop . I also chose to have the caps inside the prop arc, even when outside of this a lose cap can still make its way into the prop.

I’m using 2024T3 0.063″ aluminium and shaped so it JUST fits sideways in the fuel cap opening. Once tethered at the apex it will keep the cap from departure.

The length of the cable allows the triangle to sit on the bottom of the tank even when the cap is off and resting nearby.

I used simple attachments and rudder cable, During refueling an earth strap can go on the cap latch. The other end needs to penetrate the surface of the fuel. The body of the cap is ‘coated’ and will not earth, so use the latch!

I have also put some braid inside the tanks so earthing is possible from the external vents assuming I connect them at the vent manifold. There are options. The cap seems the simplest.

Touching the fuel nozzle to the cap latch initially may be good practice. However the fuel running quickly through the metal hose also builds up static.

This is how it will go during refueling. If I’m smart I’ll have a rag handy to put on the strake.

Cap in place, job done.

 

Strake to Wing Fitting Check

Date:  10-17-2018
Number of Hours:  1
Manual Reference:  no ref

Today was the moment of truth. I’ve moved the project to a hangar and put the wings on. Now I find out how good the fit is!

And with wings on, it looks something like an airplane again.

The fit is well within the range of a little filler. Pretty good really.

Given we have run different airfoils it has worked out rather well.

The height difference is negligible. I am well pleased.

Here we are with the top cowl just placed on top for now. It does give a beautiful line. Once the borrowed dummy engine is installed I’ll really know how it is going to sit.

Installing the Sump Lid 2

Date:  08-06-2018
Number of Hours:  8
Manual Reference:  no ref

Now the sump lid is on I can tape the sides up. For now I’ve covered this hole with its port and a couple of screws with gaffer over the top to protect it. This will be the last look at the hydramat for a while.

I went to some trouble to fit this front piece with a bracket. Strangely after cure it didn’t fit as well. Maybe the tapes just loosened off. I will fix it later, no biggie.

You can see below I have tapes in place. Just two ply of BID and I spent a while in prep work. I’ve transitioned the edges at the back on each side to allow for the seat belts to have a smooth run for the PIC.

I did the front lip the next day. You might notice I’ve gone with flox corners. That happened down the sides too.

Here’s a wide view after I cleaned up the edges this morning.

Today is a bit of a milestone in that in a very basic way the major airframe components are built.  I have wings, strakes, canard, common sump and the canopy and fuselage in existence.  I have stood back and looked at this.

There is SO MUCH still to do!!! <grin> Still, I am making progress.

 

 

Installing the Sump Lid 1

Date:  08-05-2018
Number of Hours:  4
Manual Reference:  no ref

With the strake leaks sealed it is time to finally cap off the common sump.

I found that the pipe I’d make previously was a little long so I had to reacquaint myself with the process. I’ll do an entry in ‘Strange Tips’ on this site if you want details.

With the pipe made up, I secured the fittings and installed the Holly Hydramat. A 15″X15″ special patient pending filter. Part #16-107. It has a 1/2″ NPT fitting.

I’m using a step down adapter to work with my -6 Speedflow 200 series braided stainless pipe, 200-06 and ends. 200-06203-06-D and 201-06-D.

I used a lot of flox and the 87 EZ-Epoxy to secure the sump top. The port hole is still open  so I can check internally post cure that all seems well.

Leak Testing 6

Date:  08-04-2018
Number of Hours:  8
Manual Reference:  21-5

After finding a couple of leaks with the aircon sniffer method, I went to work that night to plug them. While looking for these leaks I also found that the sensitive skin just above my lip and below the nose could detect air being forced out of the strakes. Once the sniffer identified the spot this was a secondary method for getting the exact leak position. It was best at 10-14″ of pressure. Below 8″ it was not noticeable.

I started with a fine needle and ended up with just a hole the size of the syringe. What seems to have happened is that I’ve had a leak somewhere between the outermost baffle and that leading edge I added later. So it was internal. This leading edge has a channel in it for the magnetometer wire. Escaping air got into the wire covering and traveled down that to a few locations on its merry way.

As you see above I’m pumping in epoxy. This is getting into the conduit and traveling along it. To encourage the flow, I’ve pulled out the drain hole stopper and have positioned my vacuum cleaner hose in such a way that it pulls about 10″ of negative pressure. This will help suck the glue into the leaking hole.

I put a LOT of glue in that hole. It came to the surface in two other places but I just held my glove over these and kept pumping in the epoxy. My next step was to use wet flox in the syringe and keep feeding it.

Where that black ring is was a secondary location. That got the same treatment.

It took a few more days and yet another aircon guy with a state of the art sniffer to find the subsequent leak that was still evident after all the work. It was very slow but I knew I still had an issue. I might mention it was with some concern too as the leak needed to be 100% resolved. No compromises here.

Well as you might expect the final leak was really hard to find. A lot of the problem was getting the testing gear and all the hoses 100% sealed so we didn’t get any more false readings. The final leak was…… at the drain hole plug. It wasn’t tight enough! My bad. The other leaks were real, this one was builder induced. Believe me, I paid for this.

That said, they two guys who helped out were fantastic. A big shout of to John M. who made several visits and Geoff E. who did the final sniffer search today. They understood that we had to get a result and it was refreshing to find professionals who were all about getting the right result and caring about the work itself.

My fall back position was to start deconstructing the strakes, starting with the leading edge. A seriously big job that fortunately was not required.

I did several hours more testing of course with my manometer and finally called the left strake good. The right one you might remember was good from the beginning. Next up was to open up the feed pipes in the sump, do a clean up and then fill it with soapy water.

I have no leaks on the bottoms and sides of the sump, or things would have been wet on the outside. Easy. Next will be a clean up and some plumbing followed by finally gluing/floxing on the sump top.

As a most relevant aside I used this test to determine the volume of the sump. I filled it to the back edge with the nose down. That water was measured as it came out as 16.8 liters. The sump could not be filled completely with the top off of course. I did some measurements and came up with my sump volume which would have to be pretty close to correct.  My numbers gave me 19.6 liters which were a little conservative in the measuring. So I’m calling it 20 liters for now and it might be 20.1 or 20.2 in reality.

Sump Volume is 20 liters.

 

Leak Testing 5

Date:  07-24-2018
Number of Hours:  6
Manual Reference:  21-5

You just don’t want to hear what I’ve been through to get to this point. What you want are the results and maybe something helpful if you are a builder, right?

I again confirm I have  leaks in my left strake as you see above. The #1 method for finding this was to hire an aircon guy who has the right gas and lines. We got some traceable gas into the strake at about 10″ of pressure. His sniffer immediately found two leaks and the rest seems good.

Yes I tried other people, bought a dye kit, waited days for others, found connection issues and on and on the circus went. Yes I did old school soapy water without success first, of course. Oh thats right, you don’t want to hear about the last two weeks.

Tonight I went to fix the biggest leak. The method I’m using is to pull a consistent vacuum of about 8″ with my shop vac gaffered to the removed fuel drain plug (outlet). Watching the manometer I found a spot where it has a reasonable pull.

Where the leak was I got the dremel out and made a bigger access hole. It was right were the magnetometer wires entered the fuselage, of course. No modification goes un-punished.

I then mixed up some fuel safe epoxy and got some in the hole only to see it slowly get sucked in. I kept adding and it kept slowly sucking. My idea is that plenty of epoxy should be coating the pathway through the foam to the outside world. After a fair bit went in and disappeared I made some sloppy flox. That was then applied and it slowly moved into the hole. Finally I made some stiffer flox and let that get sucked in until it didn’t want to do any more.

That I hope will do the job. I put some peel ply of the outside and turned off the vacuum. After cure we will see how it went.

There is a second leak would you believe right where the internal box was made to hold this magnetometer? More modification punishment. Somewhere in the box walls. I may be getting the aircon man back to pinpoint it. His sniffer was acting up and a new tip is needed apparently. First up we will see if the major leak is plugged.

 

Sump Drain Revisited

Date:  07-06-2018
Number of Hours:  5
Manual Reference:  no ref

Over a week or two I’ve been working on the drain point for the common sump. I decided that it would be best if I could ensure a water drain while the plane was in the kneeling position. It will work when the plane is fully wheel down as well when I’m fueled full to the brim.

For it to work in both configurations I needed to add a little ramp and test.

My first test in the kneeing position shows water pooling in the right front corner of the picture. Here I’ve added micro to that area. As I had some over I stuffed a bit in the aft corner which as you can see just rolled forward as it cured. Yes of course I cleaned up the excess.

The next water test was an improvement but I had a little pool of water sitting just in front of the drain hole. I added more micro and let it flow where it wanted.

More water testing and I’m getting close. It just needed careful sanding of some high spots.

More testing and sanding and it is excellent now. I’ve re-tapped the drain hole too. All the water flows out now with just a bit of wetness remaining but zero pooling. Job done, move on.

Leak Testing 2 & 3 & 4… Manometer

Date:  07-06-2018
Number of Hours:  3
Manual Reference:  21-5

An update on my leak testing.

Given that it might be my pipes leaking I floxed all the fittings. After cure I tested and found that they seem leak free.

I reconnected to the main right tank and did more testing over some hours and then overnight.  Yes there was still a slow leak.

Maybe the fittings in the tank were leaking? So I went to a hose place and got some NPT plugs and some fuel safe pipe sealant and did a number on all the openings to the tank.

More testing and overnight and I still seem to have some ‘anomalies’.

I jumped on the web (figuratively) and researched freon sniffers as used by refrigeration people to find leaks. That all seemed pretty expensive and complex so I thought I’d try some soapy water first.

  • The best recipe that was easy…
    1 Quart of water
    3 tablespoons of dish detergent
    2 teaspoons of liquid glycerin
    Leave overnight for better bubbles

So I did that and sprayed it around the place the next day not finding anything.

Meanwhile I have again pressurised the tank to 14″ and again I’m recording the temperature and pressures hourly. Now I’m starting to think that I need a barometer as well because I think atmospheric pressure is a factor too.

I may NOT have a leak. I’m not sure! I’ll continue to record temps and pressures over a few more days. If the pressure goes down and doesn’t come up even when things are sort of equal then thats a leak. If it goes up and down and up as it seems to be doing… well, maybe its Option 2 and I’m good.

Meanwhile I’m doing lots of other build jobs.

 

 

 

 

Leak Testing 1 Manometer

Date:  07-04-2018
Number of Hours:  3
Manual Reference:  21-5

Testing for leaks is a matter of pressurizing the strakes and seeing if that pressure drops over time. It took me a couple of days of fiddling and getting bits to have my working manometer. I’ve just taped a ruler to the back to use as a scale.

I found that if the column of water is too small it is easy to add pressure which blows past and makes bubbles which limits the possible pressure.  So a little more water in the tube helps that.

A pressure change of about 18″ equals 1500′ on an altimeter, plenty for this test. Too much and you can blow the strakes. I think around 14″ is enough really. I’ve plumbed it up with a couple of shut off valves and a tire valve (one way) for getting some air into the system. My rather anemic tire pump is not powerful enough to do any damage quickly.

I’ve blocked off the tank openings and done a test. Of course it wouldn’t hold pressure. That’s all those pipes so I’ve disconnected from the strake and I’m still finding a slow leak in the fittings. I’ll flox those over tonight. I suspect my strakes will be fine and the challenge will be getting the test to prove it!

 

Strake Leading Edges 2

Date:  07-30-2018
Number of Hours:  13
Manual Reference:  No ref

Interestingly I couldn’t find a reference in how to do this step in the Long-EZ plans. There is a bit more in the Cozy plans buts it’s straight forward anyway. Make a foam block and cover it with 2 ply UND crossing at 45 degrees. I made a good start in the previous post and spend a couple more quite long days getting it done.

After making a few flat areas to begin my curve I finally decided it might be an idea to have some sort of template. I dug up the plans and bits of paper and plastic we used once these strakes were designed and made some cutouts for B.L.23, B.L.45 and the fuselage side. The outboard bulkhead being already formed from the wing and in place served as well. So I had 4 points to work from. Plenty.

I wasn’t looking to be super accurate as this thing was going to shape itself right? All I had to do was keep that curve consistent and match the two very different ends as well as a different middle and another different bit. Thats what you get when you blend two airfoils.

I still had my leading edge mark to work from which helped a lot.

After some time it all turned into a curve that I think is ‘correct’. The gap a the top, and yes there is one underneath, were intended as I beveled the upper and lower skin here so the glass would fit well over the front bulkhead.

I went for flox in the intersections and make flox corners at the outboard ends too. The rest of the foam was given the usual micro slurry.

This leading edge layup was a really good candidate for the foil method. I cut the UND so it had a 45 degree bias one ply opposite the other sort of making it a type of BID over the two plies. Above you can see I’ve wetted out the pieces and cut them to size. The strakes were already marked that is just visible in the pic so all I had to do was line it up in place.

Foil on and nice and straight. This is much easier than cutting dry cloth in place and trying to get it all tidy.

After a lot of application and getting it as flat and clean as I could come the fun part. Yes just a few strips of peel ply. Goodbye another 90 minutes getting those four pieces down.

As you can see it worked out OK. It you’re wondering about the colour change. The foam is that tan colour just like the strakes are but I used my regular epoxy which is clear rather than the smelly brown stuff. If fuel leaks consistently all the way down there it will be the least of my problems. This stuff is fuel resistant just not proven to use an avgas bath tub.

A straight leading edge, and exact to my ‘planned’ measurements. Now there’s a change.

Still looks like some cool delta winged thing. I’m getting close to checking if I have any leaks now. Visually, these strakes are good to go.