Mud Duck Aviation Forums

Does anyone have any information on building the Agri Duck with coro. I got my plans today and will probably start building next week. I am hoping to do most of the build out of 2mm coro with a flat bottom wing and spar. Looking at the plans this should be pretty easy to convert over to proven "Spad methods. Go to the Spad site for more information on how to build with coro  http://www.spadworld.net. Coroplast comes in 4mm and 2mm and can be purchased at most sign shops (or grab some left over political signs for free). Price wise it is probably cheaper than Foam Board and comes in lots of colors. The second advantage to coro is that it is fuel proof and can easily be decorated with sign vinyl or will take paint for electric planes. The 3rd advantage (If I get it right) will be the weight factor. Using 2mm coro should produce a lighter airframe than the foam board. I will try to post a build thread in the build section so you can see how to work with this material.

Great, I look forward to seeing a thread on building w/ corroplast. 

I have addressed the factors that I recommend making changes from the plans/manual for corroplast use directly with customers that decided to go that route.  I will have dig through my out box to try and unearth some, but it is all probably common sense for a previous SPAD (Simple Plastic Airplane Design (for the uninitiated)) builder.

The most basic changes would be:

- Adding some "blocks" (lengths of 1/2" sq basswood etc.) to the inside joints were the pieces "meet up" at a 90 degree angle (not the full length of the joint, just "spots"). 
- Puncture and "scuff" the corroplast for glue joints to bond better.
- Don't forget to run the "grain" of the corroplast inboard to outboard for wings and horizontal stab.
- Use of screws to aid in fastening joints into hardwood "blocks" is not necessary, but insurance if you question your glue joints.

Basically though, there really isn't any major thing to modify on the Duck designs when converting to corroplast.  Although the FomeCor material is 5mm thick and doing a full-size Duck with 2mm may not be the most rigid structure without adding additional materials, and I'm not sure if the weight will come back to the 5mm margin when all is said and done.  I have no experience using the 2mm for anything large, so I can not make a definitive judgement about it, just my assumptions.

Greg

Hey Greg, I have built several 80" spads that flew well even two 84" deltas that are still being flown . The wing should be no problem but I will have to see if their is a weight advantage to the 2mm fuse. You are absolutely right about having to add some extra structure, it may be better to build the fuse out of 4mm. My idea is to trace out the fuse pieces and add full length tabs to the sides for gluing. I will then simply glue the top and bottom on. 3/4" foam will be used for bulkheads with light ply sandwiched on the first 2 to support the motor. I am thinking about using 2" pvc downspout for the motor mount. My core group of friends and I have built hundreds of spads, so I hope that I can come up with some building ideas that will help other people on this forum who wish to try coro. I will start a build thread in the building section. Hope the coro works out, if not I will go back to the foam board.

Oh, I failed to mention that the corroplast will work.  It definitely will, in fact many Ducks have been built with it, I just think they have all been 5mm.  I have photos of a couple, problem is they are on a failing har drive that I am trying to rescue file by file.  I checked my gallery, I thought I had already posted them but they weren't done yet, so no luck gettin you any photos right now.

The one neat thing one builder did with the corroplast version was he made the wing one piece and hinged the center section, so when he removed teh struts and the wing from the fuse, it folded in half (bottom to bottom).  then he made some kind of holders on the side of the fuselage to hold the folded wing for storage.  I have to find those photos.

I check my traffic on these forums and they do get a lot of visits, but I need to get more content on them to get more participation.  I imagine that many of my past builders only swing by sparatically, so it may be a couple weeks before a corroplast builder sees this post.  That said, the build thread would be very welcomed and an asset for other builders!

Thanks,
Greg

I just added a Coroplast board to the Materials forum and moved the topic here.

I would love any photos that you have. It always amazes me at how many different ways people can build the same thing.Once I get the build thread going I will post on the Spad forum and link to this site for the build. I may go ahead and do a build thread over there as well.