Introduction My Builder's Log My Flight Log Tips List of Builders Gallery Ideas for Paint Links News




If you have placed your top skin on and it fit snug, count yourself among the fortunate. Mine fit horribly, requiring pulling and pushing to get it on and settle into a very awkward place. There seemed to be no happy medium from one end to the other and the gap between the glass and skin was excessive.

The pictures above are of Rob Logan's. These were helpful to me in knowing what to anticipate when it gets bonded and how to go about doing it. However, going on advice from Ron Jones, I opted to cut my top skin in three sections and bond it in pieces as he did. In hindsight it required more work up front, but now that I'm finished, I have a perfect fit, the step down is near nothing and I've saved countless hours in future bodywork. I would only do it this way, if I were to do it again.

The skin was cut in two, front and back and the front was split again. I marked out the line where I would want to see the final shape. I then transferred the line onto the skin. In doing so, there was a gap between the glass and the skin of about 1/4" to 1/8". Yikes.




In the pictures above, the gap is closed up to a very snug fit by grinding down the reinforcement layer a little at a time until it fit up against the glass. The cross section of the forward portion shows how close it needs to be and by eliminating the gap I increased my bonding area and the ultimate strength of the bond.

In addition to getting the skin to fit closer to the glass, I kept sanding down my reference line and double checked by placing it in position. I drilled 1/4" bolt holes all the way through and utilized blocks for clamping with big washers and wing nuts on the inside. Another two-man job.

After the skin is trimmed and straight, the outside gets a nice tapered bevel. I fabricated the defroster dams and made a flange between the forward sections in the center for extra strength. The glass gets prepped for bonding and cleaned using ALCOHOL. (Very important). A three layer release is taped on for squeez out clean up and to insure that the canopy does not bond to the fuselage joggle.

For this to really work great I came up with the idea of building some sort of structure on and around the skin where I could use screws to put pressure around the curve and get the ultimate snug fit. This worked great! My skin ended up with NO gap what so ever! Once pressure is established I kept tightening in a row with a hand screw driver.




The rear section started and ended much like the front. Establish the line, transfer to the skin, cut, sand and bevel. I bonded a flange between the sections and prepped my skin and glass for bonding using alcohol to clean and put in a three-layer release using plastic tape.




The rear section was the real problem and when I clamped it down with hysol I had to keep adding clecos and screws to get it to conform to the contour. I ran out of machine screw and broke out the long drywall screws used to secure my plane to the trailer for the ride home. This is now the third time I've been able to use them! To keep from cutting into the skin I placed washers in between. It may look a bit odd, but it worked great.

The last step will be to fill the bolt holes. I am going to cut some scrap two-bid glass and tie cotton thread to it. I will apply flox and insert it into the hole and pull up on the thread to establish a good bond. After it cures, I'll backfill the remaining void with micro and bodywork to smooth. More images to come...


Following is the way John Kleber did his canopy jig. Nicely done!




Diving in:
Yesterday was the successful and exciting culmination of lots of work getting the canopy skins ready for bonding.  Your photos gave me inspiration!  In particular, I could see that it was going to be necessary split the skin.  Also, it would be necessary to push the skin inward toward the windshield plexiglas in order to get a nice tight fit.  So I developed a "Blocks & Bridges" system which ensures a snug fit all around.
 
I'm going to describe the process and have included pictures which might be of help to other builders getting ready to begin canopy work.
 
The new Hysol Lancair sells has only a 50-60 minute pot life.  It is very strong; however, one must have the clamping system all set up and ready for action. 
 
I think the idea of cutting the skin into several parts is almost essential!  I cut mine in four pieces.  The first cut was right down the centerline, resulting in left and right halves.  Next, I cut each half at about the midpoint.  Now I had four quarters.  It was very easy to fit each of these quarters snugly to the stiffener and windshield.  Some grinding of the windshield and/or skin may be necessary to get the skin to fit properly.  (See construction manual)
 
Clamping blocks:
Next, I installed 22 clamping blocks fairly equally spaced around the canopy.  Each clamping block set consists of an inside block, a 31/2" all-thread 8-32 screw, a washer and wing nut, and the external block.  The internal blocks are 1" X 3" poplar, and were released with bondo to the inside of the stiffener.  The external blocks are 1" X 4" poplar, and were built up at the top and bottom with 1/4" wood pads, and then released to the skin's exterior for a custom fit.  (Note:  In order to obtain sufficient clamping leverage, it is necessary to locate the screw holes as high on the inside of the stiffener as possible.)
 
Bridges:
I then installed 2" 8-32 flush screws in upper corners of the blocks to support the bridges.  The block pads are countersunk and the screws point outward.  Next, I made the bridges using 1/2" X 2" poplar for the straight bridges.  The curved bridges were made from 2" X 4" poplar.  I transferred the curvatures from canopy on to the 2" X 4" and cut 1/2" arched bridges on the band saw.  The ends of each bridge were slotted to fit easily over the screws protruding from the blocks.  The bridges are held firmly in place with washers and 8-32 wing nuts.  I then drilled two to three #21 holes at 1.5" - 2" intervals along the edge of each bridge.  I tapped 10-24 threads in the poplar for 2" hex head screws.  It is necessary to ensure these holes are drilled such than the 10-24 screw will contact the skin approximately 3/8" - 1/2" from the skin's edge.  During the bonding process, these screws were tightened as necessary to help squeeze out the Hysol and press the skin evenly against the plexiglas.  To prevent marring of the skin, and to distribute the pressure over a larger area, I placed 1/8" wood pads under each screw.  You might note from the photos that the bridges were not necessary around the front curves of the skin.  My bridges started just prior to the point where the skin/windshield are relatively straight on the sides.
 
Hope these details help the next builder with this phase of canopy construction!
 
John Kleber







Home | Introduction | My Builder's Log | My Flight Log | Tips | Legacy Builders | Legacy Gallery | Ideas For Paint | Links | Legacy News

Copyright © 2005. All rights reserved. This site is the builder's log of Don Barnes and for the purpose of sharing information and opinions related to building a Lancair Legacy. Any person using these images, ideas and tips does so at their own discretion and risk. No responsibility is expressed or implied and is without recourse against anyone related to this site. This site is not affiliated with Lancair International or Neico Aviation Inc., however, we love their aircraft.

Design by Cellar Ideas and produced with GoLive CS. Hosting generously provided by Rob Logan