Hangar Flying => Hangar Flying => Topic started by: Coppercity on April 25, 2012, 08:21:14 PM
Title: Start of my dumb questions
Post by: Coppercity on April 25, 2012, 08:21:14 PM
I acquired a partial build Long Ez project. The wings are bult to the point of cutting ailerons and adding winglets, the canard is built and the fuse looks like a stubby canoe ready for a nose, center spar and strakes. Overall the work that was done seems pretty good quality but thats based on my untrained eye. I did have the local Canard owner take a look as well and he agreed that the work looked good. I do have a couple questions for the group;
Are there any types of non destructive testing I can do on the work that has been done to ensure it is airworthy. I did learn a little about the "tap" test in my repairman school but wanted your thoughts.
Can you tell the type of epoxy used by the cured color of the parts?
Is there a problem using different epoxy with already cured parts?
What are the Epoxy recomendations now compared to what was used years ago?
Regards Eric
Title: Re: Start of my dumb questions
Post by: GlennBob on April 25, 2012, 10:51:26 PM
The " WEST " system of epoxy seems to be the most widely used and approved of. You can get different speeds of hardner. ( 205 fast or 206 slow ).
For my two cents, . .I don't think there's a non - destructive test. As long as there looks like there are no air bubbles and you can count the plys, you should be o.k. Hard to tell though.
Glennbob
Title: Re: Start of my dumb questions
Post by: Juan Rivera on May 17, 2012, 04:01:19 PM
West 205 and 206 are for non structural use. I think West 209 hardner is structural and they also make a line of epoxy called proset (I am not sure of the spelling) that is structural. Been lots of talk on the Yahoo group lately about which epoxy to use.
Title: Re: Start of my dumb questions
Post by: BruceHughes on May 17, 2012, 06:05:54 PM
Hi Eric
I thought my project looked pretty good until I talked with others who really are expert. Is your canard pilot friend an expert? How do you know?
IMHO there are about 6 people in the entire country that I would trust. If you are near one of them, you could pay to have an expert opinion. So where do you live and some of us can recommend an expert, or who we think is expert.
PTMW Aeropoxy claims to be a structural epoxy.
E-Z Poxy claims to be equivalent to Safe-T-poxy.
Poly Epoxy claims to be "tougher and stronger".
I don't know; I am a microbiologist. ;)
Bruce Hughes :)
Title: Re: Start of my dumb questions
Post by: BruceHughes on May 17, 2012, 11:33:42 PM
Hi Eric
A good place to ask questions is canard-aviators@yahoogroups.com There are a lot of canard builders and flyers on that website.
Also you should join CSA. It is $30 per year. When you join, you will get the Jan. issue, April issue and a directory. With the directory you can find most of the guys that are building. Also you can find the people that have flying airplanes already by checking the column on the number of hours on the airplane. His address is 9283 Lindbergh Blvd. Olmsted Falls, OH 44138-2407 You might consider buying some back issues, too. They probably will be useful.
Terry has written the newsletter for a jillion years. He just about breaks even with all the paper, ink, stamps, etc. etc. There is a board but CSA is essentially Terry. He is VERY knowledgeable but not an engineer.
Bruce Hughes :)
Title: Re: Start of my dumb questions
Post by: Rick Hall on May 18, 2012, 12:38:21 AM
A good place to ask questions is canard-aviators@yahoogroups.com There are a lot of canard builders and flyers on that website. ...
Geez Bruce, don't send him elsewhere ;) Fountain of knowledge here too :)
Approved epoxy formulations change over the years, some (one that I know) are discontinued too. The ones that I know of that are approved for Long and Cozy structural applications follow.
Aeropoxy. I think this is the one that cures light brown? E-Z Poxy. The replacement for Safety-Poxy, which apparently wasn't. MGS series. Ether 285 or 335, and corresponding hardeners. Pricey. West System with the 209 hardener only. Debates as to why only 209. Available most everywhere. Pro-Set Same company that makes West. Marketed/geared to industrial uses. A bit pricey.
Once an epoxy is fully cured, you can apply any other epoxy over it. With proper prep work of course. Peel-ply, or mechanical abrasion.
No NDT that I know of, other than the 'tap' test. Cured fiberglass is fairly transparent, you can almost count the plies, as well as see how it is bonded to the foam. Or an underlying layup, like at a bid tape joint. Bubbles are pretty apparent, so is a straight weave (UNI) that ends up going every which way in the cured layup.
Rick
Title: Re: Start of my dumb questions
Post by: Bill James on May 18, 2012, 04:29:16 PM
For consistency i have stayed with EZ Poxy, and am pleased with it. Re the NDT- suggest that you do the practice bookends because its fun, the 1x1 glass layup for your information, and the structural layup with the 8 layers of glass on the foam strip because it is assuring. You quickly become an expert with the glass and foam and learn to spot things that don’t look right. Bet the best two things you will do is digest the Rutan Composite document for fundamentals, and talk in person with every experienced builder that you can for shortcuts and the in-between the lines understanding of the things to do and not to do.
I have pretty well learned something from just about every person around these parts... :) Bill James
Title: Re: Start of my dumb questions
Post by: LongEZDaveA on May 18, 2012, 10:59:39 PM
I started with Safe-T-Poxy and transitioned to EZ-Poxy (supposedly the same formula), mostly because I was sure that it was tried and proven and worked for me. I can't speak about the other epoxies. It will be tough to find an epoxy with a better record on structural properties and tolerance of different fuels. Tried and proven is good...
Title: Re: Start of my dumb questions
Post by: dorr on May 30, 2012, 02:51:06 PM
I'd echo the idea of not using West Epoxy for structure. 209 formulation is unknown to me. But I love West with 205 and 206 hardner for fill and finish, using microballoons.
There is an epoxy Guru in Texas: HUNTER, GARY A. 117 Mesquite St. Lake Jackson, TX 77566 281-433-8478 lucyliu22 at mac.com
I keep a copy of the Dave Ronneberg long nose if you want a pretty nose. I also maintain a massive builder's library including videotapes.
Beagle canardfinder at ATT.net
Title: Re: Start of my dumb questions
Post by: Coppercity on June 02, 2012, 12:32:17 AM
Thank you all for the great info. I am gathering info, reading tons, and drooling each time I walk by the pieces in the hanger. I did buy a practice kit from aircraft spruce and have been doing a few of the layups detailed in the manual. I love the foam strip, it's a real confidence builder in the material. I show my students it, as my CTLS is built somewhat the same but in a mold and with carbon, they can't believe how light and strong a piece of foam gets.
Regards Eric
Title: Re: Start of my dumb questions
Post by: BruceHughes on June 02, 2012, 08:38:18 AM
Hi Eric
Before you start doing any work, find a builder that knows how to do epoxy work. Otherwise you may make anything too heavy (or too light). I had a VERY brief intro., then was on my own. I got some stuff too heavy. I started almost exactly where you are.
You REALLY should consider the plans from David Orr. They actually are from the Santa Monica EAA chapter. They are very good. If you later find that you have a CG problem, you will have room to move the battery forward and put other stuff in the nose. Many people have put the brake mechanism in the nose so you probably will be working in there a bit. That will be a good place to start (after you do the practice work that Burt put in the plans). I built a 5' cover for a spa as practice.
If you build a little heavy, it will not hurt so much in the nose, due to the CG. I have a really heavy upper and lower cowling that I will have to replace eventually. I have to get it lighter.