Ch 21 Strakes – Fuel/Baggage

Date:  06-28-2018

Number of Hours:  6

Manual Reference:

While I could leave the LE of the strakes until I mate them up with the wings, I did make a template. I’ll trust that template and really these are fixed positions. I’ll find out a lot later if it all matches up. Trust the templates I say! Yeah.

First up was making a channel for the two multi wires that go to the magnetometer box hidden in the left strake. I started with two lots of drink straws but in the end went for just the one lot of straws so the wires probably aren’t going to slide around. I left a reasonable amount at the outboard end for making the connection to the plug later.

I had to chase down the interior wall and I added some dry micro after this pic. The other holes are for the rotary canopy latch. Its busy just in that part of the cockpit. All to plan I assure you.

I used 5mt glue and later added some dry micro to hold the wire conduct in place.

Now for those leading edges. I’ve gone for fuel resistant H34 divinycell, some left over from doing the fuselage sides. Its a bit slow to shape but much stronger than the blue wing foam. Yes I did have to route a channel on this side for the wires. Easy.

You can see the leading edge position check with the aluminium channel. The foam is just a fraction too thick. Perfect for this job as it give a little leeway.

I just used 5mt epoxy to secure the foam here. It will get micro in the upper and lower gaps and then two ply of UND on top. It will be very secure when finished.

The next step was to just continue the strake curve onto the foam upper and lower.

The gaffer tape is my ‘guide’ for sanding.

I’m doing both sides at once. It ‘seems’ quicker this way. At least I finish them together.

More exact sanding to the profile tomorrow. I’m not 100% sure how I’ll do this but it will work out OK. I have the LE center marked and I can check with the straight edges so I just need to do a curve that works. I have no profiles here. We blended two airfoils to get these strakes so some eyeball engineering will have to work for the final little bit of edge. I do have marks on the fuselage and the outboard end templates direct from the wings. Wish me luck.

 

Date:  06-25-2018

Number of Hours:  7

Manual Reference:  21-3

Today started with cleaning up the strake edges.

Here’s the front section all cleaned up and as you can still see I have way too many cuts in the strake. That said, I have a suspicion it will turn out OK.

You can see the brown tinge now I’ve added micro to the surface. It certainly soaked up a lot.

First ply down and all is good.

Second and third plies down. The last ply is a reinforcement of the strake top just this side for getting into the back seat.

All done and peel plied.

Ok, this is a big deal. Its the last big layup for the major structures of the build.

Yes another 1,000,000 things to do but soak it in. Take a breath, this is the major structural parts all laid up.

This shot is just indulgence. A bit like a BD5 or some delta winged thing.

Date:  06-24-2018

Number of Hours:  7

Manual Reference:  21-3

Today was the top skin on the right strake. I’d done some prep yesterday but it was still an all day thing.

First up was a lot of micro to fill the slots and cover the divinycell. This was after some sanding and smoothing around all the edges.

As usual for these bigger layups I’ve cut the glass to length and have them rolled up and good to go. This layup is just two full plies and a 5″ wide one at the end.

Here’s the first ply down.

Here’s setting up the second ply before wetting it out.

After all the plies and a bit of peel ply round the edges.

I’ve used the EZ Epoxy which is proven fuel resistant here as I have enough over to do the outside skins as well as the final closing of the common sump. Should there be any pin holes in the underside of the top skin it seems reasonable to have the same epoxy next. I do like the golden colour too.

Date:  06-23-2018

Number of Hours:  6

Manual Reference:  21-3

Now for the left strake top. It was a similar job to the right with no big surprises.

Yesterday I spent a while getting the shine off the mating surfaces and general prep.

Today again I used a disturbing amount of flox.

Yes and flox on the joins on the top piece. I gave this whole top a wash of pure epoxy first.

I again used the hot glue and foam blocks to make correctly angled surfaces for the clamps. The top went on without problems. Nothing like practicing on the other side first. Despite my concerns of the excessive cuts I’ve make it seems to be fine.

There is no reason for this photo except I like it. It gives a feel of the busy workshop somehow.

After the left top was on I went to work on the right trimming the overlapping foam top.

The plan is to skin this tomorrow. It’s sitting well and I expect the glass will stiffen it right up. I’m still getting a bit of flex in the foam with all those cuts. I will make a point of getting a lot of wet micro in all those joins in a warm environment. I’m looking forward to a good result.

Date:  06-21-2018

Number of Hours:  10

Manual Reference:  21-3

First up was finding that leak on the left side. The strake itself was fine, the pipe I had made to the common sump was fine, the sump seems OK BUT…. Out of sight the join between the pipe and the sump had a leak where the underside joins that you can’t see. Just enough for a slow drip. I hadn’t put enough flox where I couldn’t see it. Rookie mistake eh?

I wanted to seal the pipe to sump join with flox so that fuel would not leak into the foam. This was just a matter of grinding out the area around the bottom of the pipe. Once done I filled this with flox and a bit of peel ply on top and let it cure overnight. Being winter here, the heater was again on all night and all day in the workshop. Not for me, I can put on a jumper, its all about getting the temperature up for the epoxy.

After the cure I’ve sealed the end of the pipe with a scrap bit of glassed foam. I’ve used 5mt glue and micro to make it thick for a good seal. I later want to pressure test the strakes for leaks separately so that block will stay there for a while.

All I had to do was pour some water with a little dish-washing liquid into the pipe and wait to see if it was going to leak.

Dry as a bone after leaving it all day. Lets call it good and move on.

I’ve found some stainless steel strainers for my outlet covers.

A bit of work with the angle grinder and most of the weight was gone leaving fine mesh for my cover. I did want to use a large area strainer too so that it would be almost impossible to fully block with debris. I glassed this in two stages. Just the bottom part with flox first and using gaffer tape to retain the shape where I wanted it. Stainless mesh is quite floppy once you remove the strainer rim.

Stage two was a line of glass that joins the strainer to the fuel tank wall. This is the right side done.

Now I know the left side is leak free at least with the top open I put the first stage of the strainer in there today.

The last part of this two day job was to flox on the right strake top. I got the peel ply off with a bit of a struggle and cleaned it all up very carefully. Of course I’d cleaned the tank area as well…. several times. I applied a thin coat of epoxy on the strake top underside and after that mixed a good 144 grams of flox which was soon used up.

Another couple of batches of flox were used on the strake mating surface.

Yes I has previously very carefully sanded this hat top surface so it was not shinny. Yes I had ground down the bare foam areas for some glass to glass on the insides. Yes I did wet it all out with pure epoxy before the flox. Yes I did enjoy the prospect of no peel ply for a change too.

I mated the two surfaces and wiggled them in an inch or so back and forth for a while. Next was to cover it in plastic and put on the weights. The plastic was a template I’d made of where the strakes are, but I’d put on the left one. Opps… easy fix the right one went on next. This way I know exactly where the top hats are so I could place the weights right where the flox surfaces were mating.

I’d previously hot glued foam blocks to the underside of the strakes so that I could clamp onto what was a curved surface. No way clamps could work otherwise. I used a bit of aluminum as a clamping jig and I should have a good seal at the leading edge.

All my ducks in a row here. Time to call it a night.

Date:  06-19-2018

Number of Hours:  4

Manual Reference:  21-5

My first strake leak test was done today before the tops go on. A certain well known canard builder and racer tested his strakes while open with solvent which seemed a great idea. At least I would know if the bottoms were sealed OK and if there were any other problems.

I checked in with Gary Hunter, glue guru for the canard community. He suggested water with a dash of dish washing liquid to get the surface tension down. Last time I did this sort of thing was in a bath tub with a little piece of balsa wood and a sliver of soap on the back. Instant motor boat as the soap dissolved the surface tension. My birthdays were still in single digits then.

Water is a lot cheaper than solvent and no flash point to worry about either.

I did the left side first after blocking off the feed tube outlet that goes to the sump. Just a piece of plastic over the opening with some hot glue. I had a hard time getting a seal and ended up using 5mt glue and micro on the opposite side… much easier but possibly no fun removing it later.

Oh, and the sight gauges all worked and they didn’t leak.

I was very surprised to find a puddle of water in the nose! It took quite a while to trace the leak to the feed pipe going into the sump. See a few drops here, those drops were constant drips running down the plane to the front.

Inspection with a torch and it looks perfect. However there MUST be a gap in between the pipe and the sump.

This is in the sump and I did allow a bit of lip to show through. I should have allowed for more. I think the leak which I still can’t see must be just inside that inner lip.  My plan tomorrow is to get in the sump and carefully remove material all around the lip on the inside. Then I’ll do a deep flox corner. If I try and just plug it up from the outside I’ll still probably have fuel soaking into the foam. If I try this lip idea it should do the trick.

It is VERY difficult to get into the sump area as I need to. Mirrors, the right angle dremel attachment and patience are on the list.

Meanwhile I transferred the soapy water from the left to the right side and this seems to be holding with no problems. I’ll leave it overnight and if nothing has changed, drain that side and call it good.

 

Date:  06-18-2018

Number of Hours:  10

Manual Reference:  21-3

The last couple of days have been sorting out the fuel vents and the ferry tank fuel line.

Here’s the ferry tank input. I decided to put in an earth strap so that as the tank is filled from it external pumps I can equalise the static charge through the fitting. Yes I had to scrape off some anodizing to ensure contact. This might be unnecessary but I’m happy to add a safety measure here.

Here’s the other side of the aux tank input. Floxed in place and the threads protected while it cures.

Meanwhile I had a change of heart about the vent lines. Plans have you just flox them into the tanks and run them around the rear seat belt holders. Lightweight and efficient. While I had decided to go this way, I just couldn’t do it ‘plans’ when the time came. I’m not exactly sure yet how I’m going to route the vent lines. I’m not 100% on it and the rudder cables go here or maybe down low. AND I think proper AN fittings on my proper plane are a more maintainable solution.

So two hardpoints per side in the one piece of 2024T3 aluminium were made. As you see above I’ve tapped them out for the bulkhead AN832-6D fittings which are 9/16″

The usual method for floxing in these hardpoints.

As an aside, I was going to earth all this to the bottom of the tank with floxed straps going to a click bond. Nope, I’ll use the chain dangling in the tank method instead. My reasoning was that given where the fuel caps are going it was just TOO hard to get to them to be playing around with nuts and fittings. My caps are just not wide enough or going to be near enough to a baffle.

I’ll be going with an earth strap AND a chain going to the cap which will have a bit of tube on the end making it super hard to come out. This will be long enough to touch the tank bottom. All said and done I need to connect the surface of the fuel to the fuel filler to present the same static charge. The filling person will need to clamp onto the chain which will have the strap as well. Chains alone can have a very high resistance and ‘disconnect’ momentarily.

The caps are anodised so no earth would happen there. There is a bolt on the back of the cap that I’ll use. My plan A was looking like making myself a difficult job I didn’t need. Plan B, simple and easy won out for the same result.

Floxed hardpoints on the other side.

While this was happening I got busy making vent lines for each side. Bending and flaring required. Easy to do now I have the right tools. I wish there was more!

Here we are the next day (today) with those fittings floxed into the hardpoints and the vent line for the ‘plans’ mid position vent in place.

You can see here how it ends up at the highest part of the strake. Yes I used flox to ensure it is rigid and I floxed the fitting joins too so they not going anywhere either. Yes and they are under the hat top lip so that when I flox on the top they can’t get flox in them and become blocked.

Here’s the right side which is getting busy. The second vent line is the extra one at the spar. The idea is that when the plane is ‘kneeling’, if not 100% full that vent will be uncovered and so function normally. If the second line is not there, on a hot day I could find fuel running out the vents under the plane. So the second line is a bit of insurance against this.

Now most people run some aluminum tube under the spar lip here to the mid point. Well my take is that where the fitting is, well, its just perfect! So why do I need more tube and another fitting here? No way. A tiny bit of weight saved.

Whats the black tape? I’ve floxed some plastic on to cover the tank outlets. A temporary cover. After cure overnight, if it is sealed OK I can then test the strake bottoms for leaks, separately. If they were open here I’d need the sump top on and I couldn’t test separately. Why make life harder than it has to be?

hahaha I’ve already committed to building this plane instead of sipping drinks with umbrellas in them while lounging on deck chairs in a tropical paradise. What was I thinking? More work tomorrow… lets get this thing built.

 

 

Date:  06-16-2018

Number of Hours:  12

Manual Reference:  no ref

Having sanded these sides I am choosing to peel ply a wet coat. This will keep the goo where I want it. I detailed this in the last post, now with the interior sanded there is no putting it off.

Peel ply is one of the less fun things.

I made paper cutouts for each piece so thats five per compartment.

You get the idea, its a lot of paper.

Next up was to mark out the peel ply pieces and cut them up. Yes I labeled everything and had a plan that did work.

I know you can’t see much but here we have the epoxy and ply down on the right side. It took me a day to do the left as well. The epoxy down is one thing, then its getting all the wrinkles and bubbles out of the peel ply. I’m sure there is a ZEN Master somewhere that would have a name for this sort of work.

After those two days, I got on today with removing the all the peel ply and doing a clean up, which was a lazy couple of hours. My room heater has been on for two days solid. Its around 12C outside and more than 22C+ in my room. Toasty!

Finally I added a light coat raw epoxy to the strakes concentrating on the sides where leaks would be possible. Again hard to see in the pic yet it has happened.

Meanwhile I also did a coat of epoxy AND peel ply to both strake top insides. I’m concerned I may have introduced pin holes when I scored them to get a curved fit. This is just a kind of due diligence. It may also stiffen these tops. I put way too many cuts in them and don’t have any spare foam to re make. It will be OK but I will need to ensure I have plenty of micro in the cuts when doing the top outer skins. Meanwhile getting things a little thicker on the inside tops as I have done to the inside fuel area also makes sense.

This is slow progress, doing these strakes, but I’m on it every day and it will get done.

Date:  06-13-2018

Number of Hours:  8

Manual Reference:  no ref

The last two days have been strake prep. I spent a lot of yesterday reviewing ALL the strake notes I had from other builders and forums. I have been a little conflicted on how to do the final prep work. In the early days guys got a couple of pots of epoxy, splashed it onto the inside called it good and that worked. Maybe… Other people have done this and got fish eyes… or areas where the epoxy just sagged away and had to do a lot of sanding to fix the problem. One of our gurus says no peel ply, add more thin glass instead to support a rich layers of epoxy.

Well after consideration I’m going multiple layers of epoxy, (no more cloth), not too thick and peel ply for each layer. This is a pretty big job and I think all the peel ply will need to be cut to fit for each application. That’s 80 pieces of peel ply cut to size! Yes 240 pieces for three layers. Did I mention the sanding also required?

Oh well, quit complaining and get on with it I tell myself.

As I prepared for sanding there were still a few jobs along the way.  After cutting out the upper mouse hole exits post the hat top lips, I had all these holes. My thinking is that when it comes time to flox the top on I’d have to be careful not to let any flox fall in the gaps or worse come loose and make there way around the tank for a month before trying to block off or reduce my fuel outlet.

An easy answer was a single ply of BID over the holes as you see above, peel plied of course. Now I can run the flox full length without concern when that happy day arrives.

Another issue is fuel cap placement. I’ve chosen inboard and nearer the middle than plans. Yes my cap will be in the prop arc if it comes loose so I will make all reasonable provision so this will never happen. Secondly I want my cap at the high point of the tank so for the day of the Pacific Ocean crossing I can get ALL the fuel possible in the tanks. For regular filling nose down I can still get an awful lot in and can always use the nose lift to add more if the tank cap opening needs to be higher.

This all relates to that circle of cloth you see above. That’s a piece of Innegra which is tough like Kevlar but friendlier to cut and work with. You still want a WHY? OK what if some guy is fueling my plane when I’m not there supervising or even if I am and he or she sticks the fuel nozzle in too far into our 9″ deep tanks (8″ for you plans only people). Bang! It would be catastrophic if the strake was damaged so this is a little insurance for that unlikely event.

Drain hole slope. I tested what I have with water and each side just needed a little more micro in that corner as you see above. Otherwise the drain is working very well. I will test again before closing the strakes.

Now to the sanding. I’m using that trouble light, a vibration sander and 80 grit sand paper. While I’m not going for 100% matt I am wanting say 80% non shinny before applying the first lot of epoxy inside coating. Its not like a structural bond where 100% is necessary. I’m doing this to fill in possible pin holes and as a way of going over the glass work and treating any air bubbles or anything else I find. Someone said you need your best work here, so its extra effort. I do not want to be fixing leaks! I’ll do my reasonable best and see how it goes.

Right side just about sanded.

Left side just about sanded.

Both sides just about sanded. I liked this picture so bloggers rights to include it. More sanding and clean up tomorrow and I’ll make a start with the peel ply and lay down some epoxy. I have 12 compartments to do per side and I’ll just go in stages with small batches.

 

 

Date:  06-11-2018

Number of Hours:  7

Manual Reference:  no ref

The gauges finally got floxed into position today. Yesterday was more fitting and filing and a little painting too.

I fitted the gauges yet again, marked out the locations and masked up for some white background paint. I could have just used some white silicon behind the gauges but I wanted to be in control.

Three coats of white and an overnight dry.

Tapes off and it will work out. I taped the rear gauges a little differently to the front ones to allow for the change in viewing angle.

Last night I also added some pure epoxy and wet flox to seal the ‘open cut’ areas under where the tubes will go.

Today the four tubes were floxed in place.

You can see on the front ones particularly I’ll need to add some micro to make it all nice.

I plan to finish off the fitting with a ply of BID over the tops and bottoms of course, just below and above where the fluid will enter.

Here are two of the interior tubes. I spent a while ensuring the were well floxed in. Then I added a ply of BID on the outside to again ensure a good seal.

You can see my rear tubes are a lot longer than the usual Long-EZ sight tubes. I hope to get a really good indication of full and empty with these guys. I also looked at LED lighting today and experimenting with a single LED. I’m going to look at some strip LED’s and see if they might work better.

Given that I’ll leave these tubes for now and work out the lighting before finishing them off cosmetically. Tick this one off the ‘to do’ list before I can close the stakes.

 

Date:  06-09-2018

Number of Hours:  7

Manual Reference:  no ref

Yes all day on the fuel gauges install. How can it take so long to do stuff? … well it just does.

Most builders use a pre made gauge you can buy that is excellent but I’m making my own. One reason is that my strakes are non standard. The other reason is that I have the pre made ones in my flying Long-EZ, JZE and they do not extend to the top or bottoms of the tanks. In fact anything above 3/4 full shows full on the gauges.

You can see in the above pic I have the feeder tubes for the gauges at the absolute top and bottom of the tanks. Yeah, thats what we want. It was very hard to achieve. I had to cut carefully into the longerons and make a slot to fit the top of the gauge. This took several hours the second one was in 1/4 of the time.

Here’s the gauge sitting in place. I still have a lot to do to seal it all and make the final fit. You might notice it seems a lot longer than the standard gauge too. All those years ago when I made the sides I did allow for gauges but now six years later in fact, I find that I have to extend the cutout by rudely cutting into the sides. I’ll forgive myself this time for not being able to plan ahead for this modification. Yes yet another minor mod that is yet another time soak. I think it’s worth it.

Here’s the left side. I’m not sure yet how I’m going to make it all nice. I wish I could just look ahead on my blog…. you can…I haven’t arrived at that future present time yet.

Here’s a view of the front gauge gouging, or lets say I’m extending the cutout.

If you look really carefully you can see the top and bottom gauge feeder tubes.

Here’s the front left. Not yet finished and I’ll start on the front right tomorrow.

 

Date:  06-08-2018

Number of Hours:  6

Manual Reference:  21-3

Having put in the fuel sensor hardpoints, I wanted to encase them in flox to ensure no leaks.

The initial fixing method worked out with the hardpoints being floxed in place. It was still a bit of work to get the tap through to the other side.

I’ve made a cone to go around the GEM sensors and then stuffed plenty of flox all around the edges working it in and then finishing with some peel ply to keep it in place. I REALLY hope this works and that the sensors don’t get floxed in place. I’ll certainly try to get them off tomorrow morning before a full cure develops.

The next job which has been ongoing for a while, is to make four sight gauges. Two in the usual plans position and two in the front cockpit where they are easily seen. I’m using schedule 40 PVC and some 0.125″ aluminium tubing from a hobby shop. After some careful measurements for the top and bottom of the tanks, front and back at the gauge sites, I roughened the contact areas and floxed the AL tubes in place.

I was careful to keep the ends of the aluminium tubes clear of any flox. Probably a good idea if I want this to work. Having roughened the inside of the PVC up to the small tube entry points, I’ve carefully stuffed the ends full and left them for the cure.

Meanwhile the strake fuel outlets needed a bit of work to ensure a smooth ramp for the fuel to flow into the common sump.

The past few days I’ve also been working on the strake drain points. Get a round peppermint, roll it down the strake and see if it stops at the drain point. As you can see here it stopped in the corner…so a little assistance is needed.

I’ve just let some miro to flow where it will to ramp to the drain point.

This ramping needed a little smoothing out. Now I can see maybe filling up the rear is also needed. Its not a lot of micro. I will get this right but it may take a few more goes. This time I’ve used some peel ply and dryer micro so I can get a steeper ramp towards the outlet. More pics later as I see how this works out.