Over the last couple of weeks, I have been working on covering my tail parts of my Legal Eagle XL. I first had to do a lot of watching videos both from the XL video I got from Leonard and from youtube of course. I found so very good instructional videos covering the Stewart System that were very good and informative. So I actually ended up using two different types of glue – I started by using Poly-Fiber Poly-Tak and that worked reasonably well but found it was really a mess to work with. I also did not like how you had to apply and bond material straight away like working with superglue or something. But I must say when I glued the material on used Poly-Tak is it not going anywhere!
After doing a couple of sections of the tail with Poly-Tak I wanted to try something like the Steward Systems Echobond which I saw on YouTube. I did not have any of that and found it very expensive in comparison to Poly-Tak but while doing research I found others using Fastbond 30NF which has the same makeup as Echobond according to MSDS and is reported to work. I already had a quart of that so I figured I would give it a try.
Working with Fastbond/Echobond is so much better, in my opinion, to work with! These adhesives are a contact adhesive so you can apply the glue, let it sit for a bit to become just tacky (about 30 minutes after applying), and then apply the material by rubbing it in place. I also used a hot iron to bond it even better when I had final placement. To finish the process just apply more glue over top of the material that is in contact which the frame part or what have you.
After I covered all the tail section parts I also decided to tape the edges with 2 and/or 3-inch tape for safety. I think it was good enough without the tape but better safe than sorry. The entire process was definitely a learning experience and I can tell the difference between the first part I covered and the last!
I am also looking at the Superflight U500 fabric adhesive system and think that is what I will use with my wings. It is similar to Echobond and the Stewart System process from what I can see but it does seem like it will go a lot further glue wise comparted to Echobond because it is sold in a concentrated form using it mixed with acetone 1 part adhesive to 2 or 3 parts acetone. So anyway plan on using that for the wings.
My question: Is all spruce from number 1 lumber grade or does it have to meet an aircraft specification?
Also, is the plywood used in the spar construction standard lumber yard stock or does it have to meet a special aircraft standard?
For safety, I have followed plans which specify aircraft-grade for both spruce and plywood. I do know there are some replacements that can be had for spruce and also that if you know what you are doing you can get it from local sources (if available). For ply, you really do not want to use local standard lumber yard stock – not enough layers with a standard stock. I know some have used marine grade in some cases successfully but always need to think safety.
Another key is weight – spruce is ideal because of its strength to weight ratio – not too much matches it and when building a part 103 ultralight, weight is everything.
Of course, other designs use different materials like aluminum and composites eliminating that need for wood.
Hope that helps.
The aircraft grade woods used in the Legal Eagle will not set you back compared to the feeling of safety you will have at a few hundred feet above beautiful old mother earth. Give up a few pops and candies, and you will have the extra couple of hundred bucks to get the good wood. Might even loose a couple of pounds. đ
Sure and that is what I have done, BUT, the problem is in some countries it is getting very hard to get spruce at all let alone “aircraft grade” and why other woods and materials are being considered. I personally like the idea of going to an aluminum wing or even better carbon fiber but both have their issues. One is a redesign of the wing for those materials (not something I am comfortable doing!) and two of course it cost.