WING TIPS

 

View of warped area on wing tips View of the warped area on the other side

When I took the wing tips out of the box, they had been in there so long that they were warped on top and bottom.  Unfortunately for me, they had been in my possession for nearly a year so I did not have the nerve to send them back.

Making the installation template Template on the leftwing

 

Before I could worry about the tips being warped, I decided to install them on the wings.  Before I could install them I needed an installation template.  Above left I am making a template using the drawing supplied with the kit.  The next photo shows the template on the left wing (The wing is upside down.). The template I made is in two halves. I did this for ease of removal and installation.  Notice by the dates on the photos that it has been two years since I took the tips out of the box. 

 

Warped area on the left tip Gap between tip and lower skin

The next step is to fit and drill the tips.  I taped the tip to the wing (above left).  The arrow shows the warpage that is making me crazy.  The arrow above right points out that the tip does not exactly fit the contour of the wing.

Clecos in bottom of left wing tip Clecos in top of left wing tip

 

 I drilled one hole and installed a cleco, and drilled another and installed a cleco starting from the front.  I did one hole at a time in order to keep the gap I pointed out to a minimum.  The two photos above show all of the clecos installed.

 

Marking the tip for trimming The trim line

Before I drilled the attach holes in the tips, I had to trim a little material off of the flange.  I forgot to photo graph this while working on the left tip but above are pictures of what I did on the right. The procedure was the same.  It turns out that the width of the flange needed to be about the same width as the re-enforcing strips.  I clamped a re-enforcing strip to the tip, drew a line on the tip (above) and trimmed to the line.

RH tip after trimming RH tip installation in progress

 

The photo above left shows the RH tip, which is upside down after it was trimmed.  The material removed is on the work bench.  Above right the tip is taped to the wing and the drilling has begun.

 

Wing tip to aileron mismatch Fore and aft mismatch

Above left is an interesting photo.  The aileron and the RH wing tip are not matched.  I used the same contour board as I used on the left wing.  The photo above right shows a fore and aft mismatch as well.  I will deal with these two issues a little later.

Making an internal contour plate Internal contour plate installed

 

My next task was to attempt to remove the warped areas in the tips.  In order to do this I first constructed an internal contour plate for the tip using the wing as a template.  I wanted to be able to keep the the shape of the tip at the attach point. 

 

Honeycomb Honeycomb cut to shape

To stiffen up the tips, I decided to re-enforce them with honeycomb.  I purchased 1/4" Nomex honeycomb from Fibre Glast Development, Corp.  I also purchased some vacuum bagging supplies at the same time.  Before I go any further I want to say that I am being way too anal (fanatic?) about these tips.  There is really no need to go this far but remember, "recreation and education."  I am doing this out of desire not need.

Right wing honeycomb in place and bagged Close up of bags and vacuum lines

 

Above is a photo of the right tip after I mixed resin and brushed it into the tip.  I put the honeycomb over the resin, a layer of bleeder cloth over the honey comb, a layer of breather material over that and a bag over the whole area.  It didn't work.. The resin never set up for some reason.  I think that it may have been old or the hardener may have been bad.  Part of the problem also was that I had to many steps to take prior to mixing the resin so I may not have put enough hardener in. 

 

Wing tip cut in half Small area with honeycomb weighted down

At this point I am really getting determined to stiffen up these tips.  I cut the right tip in two sections along its original seam (above left).  I cut a smaller section of honeycomb and also cut some 4oz. fiberglass cloth to go over and under the honeycomb.  I mixed resin and  brushed it on the tip. I put cloth over the resin, put honeycomb over the cloth and laminated another section of fiberglass cloth over the honeycomb.   I put bleeder and breather cloth over the top.  I put a piece of aluminum over the breather. I then weighted the assembly down to the flat surface of the table with some plastic tubs filled with water.  This was  where the worst of the warped area was.

Both tip halves with honeycomb Re-enforced tip halves

 

I repeated the procedure on the other half of the tip.  After the lay-up sat overnight I removed the weights, the breather and the bleeder cloths to leave a very stiff aft half of the upper and lower tip.  The warp was now gone in this area.

 

4 oz. cloth to go below honeycomb   Honeycomb cut for the rest of tip half

My intent was to stiffen up the entire tip with honeycomb so I cut some 4 oz. cloth first (above left). Next I cut honeycomb for the rest of the tip half (above right).  

Lay-up waiting resin Bleeder and breather over lay-up

 

I then cut cloth to go over the entire tip half.  I cut bleeder and breather to size above right.  The bleeder is a nylon type of material that looks like fiberglass but the resin does not stick to it.  You can see it peeking out from under the breather.

 

Lay-up in vacuum bag Vacuum pump

The next thing is to place the entire lay-up into a vacuum bag.  This bag was made from 3 mil plastic painters plastic (the thickest available size at Lowe's).  The bagging tape along the edges came from Fibre Glast.  Above right is the vacuum pump hooked to the lay-up. 

Second vacuum pump Vacuum gage needle moves CC

 

Wouldn't you know it?  I had a leak in the bag.  The solution was to attach a second pump above left.  The photo above right shows the guage on the first pump after I attached a second pump.  The needle turns counterclockwise so as you can see the vacuum is quite high.  The leak problem was technique and I shouldn't have the problem on the next lay-up.

 

Finished and cured lay-ups Fit check

Above left is a photo of the two right hand tip halves after the polyester resin cured and they were removed from their bags.  At right is a picture of the upper half cleco'd to the wing.  The wing is actually in the vertical storage fixture so the photo is rotated 90 degrees.

Aluminum tape to hold the halves together Tape was put on with halves cleco'd to wing

Next on the agenda is to attach the two halves back together.  To hold them temporarily I used aluminum tape.  I cleco'd both halves to the wing.  Next I clamped the trailing edge area to the trailing edge of the aileron (above left).  This was so the trailing edge area of the tip would conform to the same area of the aileron (see the left photo in the seventh row from the top on this page.).