Wheel Pants/Gear Leg Fairing

Date:  08-14-2019

Number of Hours:  30

Manual Reference:  no ref

The pants are coming together.

Plenty more sessions of fill and fair.

Then the edges needed more detailed work. I’d fill one side with release tape, clean that up after cure then then tape the opposite side.

Never pretty but with each fill and sand and fill and sand I was getting closer. You can see I have this offset sort of thing with part under and part over interlocking the halves. Trust me, it works.

Here we are starting to look like real wheel pants or spats as some people call them.

These many days later I have pants that are ready for the post cure process. In other words, roughly done.

After all the work I am pleased with that we have at this stage.

Yes they look like proper wheel pants. You might notice the bulge on the left side of the pic. This is mainly the angle of the photo but it was the way I achieved tire clearance on the outside without altering the aerodynamic drag reducing dimensions of the pants. In other words that straight down side I mentioned and showed in the last post.  This is my excuse for the slightly bulbous shape at the bottom and I’m sticking to it. They look OK from all the other angles! I’m calling it a good result and a win. You may think otherwise. I do get a lot of the tire covered this way which is the goal of wheel pants.

Date:  08-05-2019

Number of Hours:  28

Manual Reference:  no ref

Still not happy.

Here’s what I had to do to the bottom of the pants do ensure tire clearances were adequate at the edges. This side was worse than the other.

The problem was that the pants tended to deviate from straight down and pucker inwards just a little. This of course happens in the worst place possible. While I’ve seen lots of pants with that curve at the bottom, it just looked wrong and I had more tire exposed.

The point of pants is to cover as much tire as possible and still have them functional.

The solution was to rebuild just the bottom area with a lot of glass. Then I could thin the glass from the inside and get the clearances needed without the ugly cutout curves.

This took four 16 ply layups, 64plies and a whole day to do.

After a bit of a sand and trim I still didn’t have enough glass on the pant rears. Two more 16 ply layups. Thats 96 plies all up. I did them foil on plastic and two ply thick making 48 operations.

Yes, next up was a lot of grinding and fitting and a great deal of the 96 plies was selectively removed. The pants of course went on and off multiple times and the clearances were reestablished.

You might notice that the internal baffles I spent a couple of days on are now gone. With them in place the pants didn’t quite fit by a tenth of an inch or so. That little bit of flex had gone. An hour of grinding made them a memory. I’m not going to fit another set and that good idea will not be happening. I could make it work, but not this lifetime.

First nose ‘fill’ to get me started. You might notice the front lower edge of the pants look ‘normal’ now.

This gives an idea of the work. See how the right side in the pic is relatively straight where previously it puckered inwardly just a little.

Another shot showing a straight side. The whole problem is that I should have :-
1. Cut out the centers, added an inch and rejoined them
2. Bought pants that really do fit a Long-EZ properly (not ones advertised to do so)
3. Made my own pants from scratch

Lots more fair and fill work but I’m over the hump now. More pics will follow as that proceeds to better illustrate the fine result. If you need pants for your Long-EZ, I am NOT available for the job.

 

 

Date:  07-30-2019

Number of Hours:  34

Manual Reference:  no ref

I’ve been about a week on this part of the pant refit. While I was also working on the canopy fit this was the main task every day.

The back half of the pants being only two ply weigh very little. They also tend to oil can and will not be strong enough. I decided to use the technique from the Chapter 3 Education section of the plans. This has a bit of foam glassed in place that becomes amazingly strong.

I started just making up a foam wedge as you see above, They are so light a breeze will blow them away. I did one side, let it cure and then turned them over and did the second ‘strips’.

After microing these in place and after that cure I covered them with two plies of BID. I probably could have just used one ply in retrospect. Wow suddenly I have very strong rear wheel pants.

The next issue I knew was coming. As I am insisting on the rear pant section being the ones that come off and on with camlocs. Guess what? I just miss out on easy access to the tire valve by about half an inch. I could get a filler head in there but it is tough. I made a cutout for access. Easy, except I now have a hole in my pants. Yuk yuk… not all that funny.

Here’s the problem better illustrated. Of course this is all part of the plan.

Meanwhile I had to fix another problem. Where I had added glass for the camloc lip right at the bottom it had set about .25″ inboard. This is exactly where the pant and tire are close,  I lopped off the offending glass and added more plies sitting correctly to both pants. At the same time I added glass on the inside of that cutout to make a lip.

This might be easier to see, extra new glass on the bottom of the pant and a whole lot of lip glass in the middle. That lip is needed for the next outside ‘tab’ layup.

Here’s the outside tab that will sit in the lip.

Yes its a mess. I also added to the ‘tab’ outside with some extra flox so I could get the shape more exact. That initial tab layup was three plies underneath and one on top to make a sandwich.

Clear as mud? Well here’s the lip around the tire stem cutout after some cleaning up.

Here’s the tab after a bit of a clean up as well. It will be ‘pretty’ very soon, I promise.

Meanwhile back in the rear of the pants, more was needed. I made up a slab of foam with just one ply a side and that has had a few days to cure. The concept here is that I need to close off the rear pant about 2.5″ back from the lip cutout. This is so that it doesn’t fill with mud and FOD or even snow from less that ideal runways.

Above is the slab of glassed foam and paper cutouts I made of the pant openings a couple of inches in.

After a bit of trimming you can see I’m on the way to a good fit.

After more trimming I microed the baffles in place. After that cured I added one ply 1″ tapes to finish off. Wow those back halves are rock solid and still not too heavy.

Lots more to do yet on these wheel pants. I spent a couple of hours fitting them and opening up the tire area. Now I’m not happy with what I just had to cut away to get the necessary clearances. Of course I have a plan to correct this.

 

 

Date:  07-21-2019

Number of Hours:  30

Manual Reference:  no ref

The saga continues.

The tabs worked out OK, not perfectly at the bottom. Gravity had an effect during the cure. I may have to address this later on the other side as you might see below.

Its still a good result with the swapping of which side the tabs were on.

After a few more hours on my knees checking and rechecking, I was good to go for the front nutplates. The pic shows how I mount them on the outside to match drill holes for the soft rivets. I’m using soft as we are dealing with very lightweight fiberglass pants not steel ones!

The concept remains that I’m happy to have light and simple nutplates and screws on the front with a larger screw at the wheel hub and new fitting. These take a few minutes to remove and are not ideal for in the field when quick wheel for inspection and air is needed.

This fit has developed into an unusual under and over system with the ‘tabs’. It works.

Some days later I had some of the camloc receptors installed as well as nutplates.

With just screws on the bonnet and two on the wheel hub area these front pant halves are rock solid. This shot shows the addition of the two ‘inside’ camlocs.

There is great clearance on the inboard side. Outboard I had to be very careful with camloc placement.

With two camlocs each side at the pant join I found I only needed two more to make the rear pant ROCK solid. One at the top and one where that cleco is. Through this fitting process I have added one fastener at a time and then checked the fit. I am really trying hard to avoid a bad fit that I can’t fix with a handful of filler. <grin>

While pretty rough, I’m getting there with all the fasteners in place now.

Here’s a view down the side where I have a bit of cleaning up to do.

Pants are on and secured. Next up is addressing the excess flexibility I’ve produced because they are so thin and light. I need some stiffeners for the rear sections.

Date:  07-14-2019

Number of Hours:  20

Manual Reference:  no ref

This refit continues, bit by bit.

Remember this new nutplate fitting? I then tried to fit a nutplate inside and it was about 1mm too narrow. Yes I checked before I made it but I was still wrong. Yes I only had to make it in two parts because I couldn’t get a piece of box aluminium the correct height as I did for the other gear leg.

This is the remake of that which works out and gobbles up another hour or so. Maybe I could have made a hat section out of steel and careful bending? Well maybe next plane (HA!) or if I get some sheet metal skills. For now cut and shut with existing pieces is more in my wheel house. Probably weighs less in ally and doesn’t need a prime and paint either.

The next little issue is that I need to have the pant thick enough to do a counter sunk hole on the outside so that I have minimum drag here. Why have a screw in the breeze if its not necessary? I also need slight padding to manage the gap between the fitting on the strut and the inside of the pant as you see above. This way I can exactly control how the pant sits on the side.

I went for a 12 ply layup as thick enough. I tried doing it in one go and threw that mess away. Making 12 separate one ply circular layups on plastic and foil and then stacking them one by one works for a really tidy result.

Here’s another issue after cutting away the old hard points that were not needed. The sides of the pant are was not thick enough to support the coming hardware fittings so I’m adding a three ply BID strip to the front halves in four places.

I’ll have to add to the top section later as well depending on how other things work out.

I also has to do a couple of 1 ply patches over some old hardpoint holes. They got some micro in the holes as well. This seemed enough for this cycle and the whole mess got to sit around for the epoxy to cure.

Next up I refitted the pants and added a few more clicos. At this point I’m satisfied that the pants attachments work with the new small gear leg brackets. They are rock solid and all lined up OK.

Now it would have been great to do the next part on the gear leg but there is no access. I pulled the pants off and reassembled them with clicos, hot glue and sticks.

Here we are on the inside. See that long flange on the right side. I really wish that was on the left side.

This pic shows one of my 12 ply hardpoint layup spacers too. Anyway, with the pant assembled from the outside I am able to remove the flange. Yes it was a little tricky and I had four of them that had to go… but not at the top. I’m hoping my idea works out for that area.

I’ve gone for a six ply flange. Here it is above just before I cut it into four pieces. I still really like the layup on plastic and foil method.

Here you see one of the four new flanges installed.

I’ll give it at least two days before trying to get the halves apart and find out if I’m on the right track with this new attachment plan.

Date:  07-12-2019

Number of Hours:  16

Manual Reference:  no ref

The wheel pant fit, even the pants themselves were going to need fixing and finally I am here to address the issues. These things need to be in the ‘right place’ aerodynamically and I need easy access to inspect and pump up the tires in-between the annual maintenance.

I spent over a day on my knees in the hangar playing with the laser and sorting out where my pants were in relation to the rest of the plane. Its pretty easy now, I just get the longerons to 2 degrees up and my self leveling laser will draw a straight line.

The line needs to sit at the ‘point of pressure at the nose and in the middle of the pant tail. The pants themselves also need to be in line. Oh and the nose and tails of the pants probably should be equally spaced from the center line of the aircraft and exactly the same distance fore and aft to each other just to be tidy.  I have plumb bobs and squares and rulers for that little game.

I’ll spare you 20 or so more pictures. I was pretty much in line but only at 1.2 degrees nose down when I wanted 2 degrees relative to the longerons.

I spent some more time seeing how I could tweak a few angles. After a while I tried some clecos and discovered I might be able to get these pants sitting correctly.

With even more clecos and a lot of thinking I started to get a plan on how to not only have the pants where they need to be BUT also some way for getting half of them on and off easily.

I’ve decided to make the front half the more permanent ones using ordinary screws. The rear half will get camlocs for ‘in the field’ maintenance (pump up and check). Instead of the three nutplates on a big ‘Y’ bracket I think I can make it work with these little guys as you see above in the pic.

Here I am setting the pant hole position using a modified bolt. A blow with a hammer makes an exact mark for the hole position.

OH, and notice I have the big back-plate in this photo with the three nut plates?

Here’s the completed new mini bracket with the nut plate installed. I just used some box aluminium and cut it down a little.

Oh and notice the big back plate is gone in favour of a little plate without the three nut plates?

This is the bracket I’m working on for the other pant. The ideal gap between the pant and bracket was just slightly smaller than the other side. I had to improvise a bit given there was no box aluminium the right diameter. I’ll do the nut plate tomorrow.

Now you might notice the Y bracket in the photo on the floor. This is what my new bracket replaces. I found that by attaching the pant to the bonnet on the gear leg I didn’t need the 3 attach point bracket after all. Its also a PIA to fit onto. Getting rid of it is part of the ‘lets make it easier’ solution.

There are a lot more little things that need doing to make this work according to my self set brief. I’ll try and document most of the details as I go.

Date:  06-30-2019

Number of Hours:  16

Manual Reference:  no ref

There needs to be a small gap between the fuselage sides and the main gear. Obviously when the main gear is loaded with the weight of the plane, with different fuel loads and when landing or even with a small bump during taxi, the gear will flex.  If the gear fairing is just bonded to the sides, that join will crack.

The other issue is that we need to smooth the flow of air here to reduce ‘intersection drag’.

I spent a while getting a little former made for the aft curve. I tried stiff cardboard first. It tended to droop a little so some scrap metal did the job. Who doesn’t like doing things twice?

I used just a hint of hot glue to get the little extensions sitting right.

I had some modeling clay for making the curves. Yes two types.. this is the wrong type. Its too stiff or maybe it is too cold in the hangar, middle of winter here after all. I pressed on anyway.

I was determined to just get this done and was less interested in the perfect job as I was getting some tape on that ugly clay mess.

Late that night two plies of BID was wrapped around each leg. As I was driving home after a day too long I thought of all the things I could have done better. Particularly at the trailing edge where there were now 4 plies if you include the wrap of the ends. Way too much for a crisp result. I also thought about how I should have used some light clamps at this trailing edge to pull it all together.

Two days later after the cure I managed to get both fairings loose, clean up underneath and begin the trimming process. A much smarter person that I would have done this job before installing the wheel pants. There is a cuff now that prevents removing these fairings from the gear leg for a MUCH easier clean up.

This illustrates the concept. The fairing is bonded to the leg just away from the fuselage with no load as it will be in flight. With a load on the ground the flexing of the leg will move the fairing away from the fuselage.

This is getting closer. I think those trailing edges are too thick. After this shot I filled the fairing with a little flox and micro mixed. After that cured, I removed most of it and then had a bed to thin those trailing edges from the outside with a little meat in them. I’ll get them nice.

Meanwhile I needed to get those fairings on for real. I used cardboard spacers and floxed the top of the fairings in place where they met the gear leg. To be tidy, I added one ply of BID as well. The clamp’s are to ensure nothing moves and that gap at the fuselage remains close.

Don’t even ask me how we are going to paint this so the intersecting gap remains. I’m thinking razor blades and a careful line. Yes I need to do some filling, yes I’m not 100% happy but these did happen quickly and I’m a man on a mission. The clock is ticking. There is all the time in the world for safe. Plenty of time for good. No time left for perfect.

Date:  06-17-2019

Number of Hours:  16

Manual Reference:  no ref

Next up was to rebuild and profile the left gear leg fairing.

Pour foam is fun stuff. Yes and a little hard to control.

I tried being more sensible for the second leg and made a sort of cardboard cradle for the foam to expand in. I still used way too much inefficiently. This is what power tools are for.

A lot of cutting and then sanding later along with prolific profile work and I had my ‘top side’ shape.

You can see here how the trailing edge is mostly new material and that the profile is at the line I wanted it to be, quite a long way from the original that you can see outlined in blue foam at the fuselage.

I did the usual coat of micro as a hard shell, which this time of year took two days to be dry enough to work with.

Two more top plies down.

I’ve skipped a few photos here as it’s nothing new. I did 2 ply layups on the undersides after the top pieces cured. I did clear out the trailing edge about 3/8″ to ensure I’d get a glass to glass closeout. Just to be sure I clamped that edge together for the cure.

Here we are back were I started. Except the profiles are now what I consider correct for this fairing. Mistake fixed. If I still have it wrong, please give me a few days of happiness before letting me know.

Date:  06-13-2019

Number of Hours:  14

Manual Reference:  no ref

I thought the gear leg fairings were pretty much done two years ago. I was wrong.

A very knowledgeable friend noticed my fairings in a photo and asked if I was going to fix them. He said they were at the wrong angle at the fuselage. I first established a line parallel with the longerons but close to the fairings so that I could do some measurements.

My fuselage is on an adjustable stand. This made it was easy to get the nose into a 2 degree up angle with the self leveling laser and a spirit level to draw in the lines I needed.

The gear at this point should be in line with the air flow with the plane at cruise angle. That would be about 2 degrees nose up at maybe 180 knots. My flying EZ is 2.6 degrees nose up at 140 knots so I’m thinking a little flatter when you are faster.  That trialing edge should be where the red laser line is.

My gear is 2 deg trailing edge down. Its should be 2 degrees nose up! Opps. I am 4 degrees out or 0.8″ wrong at this trailing edge against the fuselage. When doing the install ages ago I found my Eureka pre cut fairing pieces fitted in only the one place. At the time I didn’t really understand where it was meant to be. Now I do. WRONG!    …so I picked myself up, dusted myself off and went ahead with a fix. Only looking forward, never back.   A lot of dusting myself off was to come.

I decided to do one leg at a time so I could use the existing gear for measurements. Out came some sandpaper on an air power tool. In an hour or so I had a pretty sad looking gear leg. Another hour or two got the underside (or top side as we are inverted) in the same distressed state.  The angle is pretty good at the tire pant end which meant I could at least leave that alone.

Next up was a lot of pour foam. That stuff is really hard to get upside down. I had a few goes at that until some sort of technique evolved. Not really pretty is it?

I made rough templates from the CNC cut cores that the fairings came in. Fortunately I saved these and given they are a negative of the cut piece I just traced the shape on some cardboard and cut them out. Instant (quick and dirty) template.

After a loit of hand filing I got the profile you see above and with time had this all the way down the leg.

The under side was much harder, only because it was…the underside. I still got there.

This shot gives you the idea that I’m close to a good profile and ending at the correct place now 0.8″ (up) from where the airfoil was. It looks better in real life and quite accurate. After fiberglass and a light fill it will be excellent. That’s my plan anyway.

Before glassing the gear here I felt the need for a coat of micro to stabilise the foam and fill in the ‘porous pour foam’. It will probably need another coat after cure that I will then sand for a good bonding surface. Given the cold weather here I may be two days in between coats.

Meanwhile before I went home I spent another couple of hours getting the left gear leg in a distressed state ready for battle tomorrow.