The Poet Creek Express - Foamie Hybrid

[KCStudly]

Thanks again for the compliments, all.

Bill (Wagondude), The idea is to use the hinge on the cabin side clamping the excess flap of canvas (to be trimmed off later), and just fold the hatch side of the hinge back on itself. Do I need to worry about the glue wicking across the gap between spars?

LFH, I’m probably going to use the same material that I make the fenders from. Most likely .060 mill run aluminum, although a nice big engine turned pattern would be really nice. More likely I will have them powder coated the same metallic silver that I used on the rear galley floor edge and hatch actuator brackets. Diamond tread would be another option, but Karl seemed to think that it wouldn’t fair as well in the break press, and I don’t plan on using any trim on the edges, so don’t want to worry about partial diamond nubs at the cut edges

OP, Okay. What would be the advantage of the strips over using a thin sheet? Just the fact that I can get them out of the stock I already have on hand? (I think I may have just answered my own question!)

Maybe slather knocked down GS on, then clamp a piece of plywood to the side wall with a release agent; let it vent out the top? Again, probably more fraught with trouble than just using spackle (filler) and sanding back.

Tony posted a link to a Rutan composite instruction manual over on your Foldable Foamie build. I didn’t want to clutter up that thread with my thoughts related to my build, so I will comment here. I found it interesting (and a little discouraging) that they call for a micro slurry (50/50 microspheres and epoxy by volume) between foam and the first glass ply. This means that the cloth would need to be laid into the wet coat, rather than first positioning the cloth and wetting out thru the weave. All of the kayak builds I have looked at wet thru the plies, but I guess the difference is that there is less chance of delam with epoxy soaked into wood than with foam, so keying into the coarsely sanded foam is more critical.

The West Marine system says to avoid trying to place large sheets in a wet bed because of the difficulty placing larger sheets, and not wanting to shift things once they start to cling. So I guess if I go with glass I would be building a boat, not an airplane.

The 36 grit prep seems very rough to me. I guess they want a really good key in, and hence the micro slurry, but I would expect to pull out some large chunks at that grit, even tearing/crushing some voids into the foam, ending up with a much heavier buildup. I have had that happen when pushing coarse grit. Sometimes the grit grabs into the foam and then tears out chunks or pushes the foam to the side crushing and tearing jagged pits, rather than grinding away smaller particles at the surface. They do say that there is a difference between the airplane quality foam and insulation foam, so maybe that makes a difference in the ability to use such a coarse grit for surface prep. Testing is indicated.

I can see where your (OP’s) slitting technique might be an advantage to the slurry in some ways, but can't imagine it working well with some of the fillers used to make the foam fair before starting to glass, especially not the spackle I have been using. I would be concerned that the spackle might break up. Maybe more testing is needed.

One more thing I don’t want to forget before making a final covering decision is the difficulty laying up epoxy on vertical surfaces. I can keel the cabin over some without too much trouble (as I have been doing), but to lay it over on its sides to allow a completely flat layup of the walls would get to be an involved process with considerable risk of damage.

Too many things to consider.

Anybody catch the lunar eclipse tonight? Pretty cool.

[Wolffarmer]

Wait until you see what I bought today. Should get it home next sunday. Have to get a trailer to load it on.

[KCStudly]

Let me take a guess; cast iron table saw?

[Wolffarmer]

Aluminum Travel Queen camper ( pickup bed style ) The top is rounded over and of one piece which I like. inside is rough shape. Water damage around the front vent. Going to use the part from the bottom of the windows and up and make a trailer. At least that is the plan. But that rounded one piece aluminum should be easier to keep water tight. Just watch those vents.

[GPW]

“ Sometimes the grit grabs into the foam and then tears out chunks or pushes the foam to the side crushing and tearing jagged pits, rather than grinding away smaller particles at the surface.m “

Try sanding in only one direction ... Think File !!!

[KCStudly]

Sand in one direction - Yes, that is probably it. Need to reduce pressure then lift at the end of the stroke. Easy to comprehend in theory, but for some reason not always so easy to execute. Took me forever to learn how to pat my head and rub my tummy, too.

Truthfully, I don't think it is strictly a one direction issue. I think it also occurs when coming to a stop with too much pressure; the grit bites in and tears.

[Atomic77]

Since a particular name keeps getting mentioned I wanted to add my useless two-cents worth...

I was in Coeur d'Alene Idaho when our team owner comes around and quietly tells each of us that we should expect a very prominent visitor to our pits. Actually this is a fairly regular occurrence; typically a political figure living near the race site, or a movie/recording star of some kind. John Travolta had a four-million-dollar condo near by so we thought it might be him. ( Side note: At the beginning of one of the heats a helicopter came in real slow, hovering over the race course, then landing right in the middle of the track to take pictures. The heat was black flagged and all the boats had to return to the pits to refuel, reset, restage and start the heat almost 40 minutes later. Who was this obnoxious idiot who stopped a sanctioned race for his own personal photo album? John Travolta. There were no fans of him on that day, mostly just a lot of words that I cannot repeat here.) Anyway, our visitor to the pits whom you might have already guessed, was the famous Burt Rutan... and let me say first hand, what an amazing, brilliant fellow. He hung around all day and each of us got to spend personal time with him to explain our technical positions on the boat. He seemed especially interested in my position, which is wing calibration and carbon fiber lay-up. He was fascinated with the combination of hydrodynamics and aerodynamics that make our boat both float and fly. The man is a genious and I was honored that day to talk shop with him and swap a few stories. Not to mention his huge mutton-chop sideburns were completely beast! What an interesting day to say the least!

Sorry to hijack KC... I don't have many people I can share that with who would get it... Thanks.

[tony.latham]

Since a particular name keeps getting mentioned I wanted to add my useless two-cents worth...

Michael:

You were obviously doing something that intrigued him. I'm guessing he learned something.

I saw this build of his way-back-when:



He named it the Boomerang. Foam and composite.

Tony


p.s. Now that Michael and I've stolen this thread, we can give it back to the KC and his PCE.

[KCStudly]

Thanks for sharing that, both of you. I get it, that was super cool. Don't ever hesitate to share cool stuff like that. By now you should know what we like!

[GPW]

There ya’ go .... Foam and composite aircraft construction , and apply that to trailers ... Burt Rutan has been our Hero for many years now !!!

[KCStudly]

Aluminum Travel Queen camper ( pickup bed style )

Randy, I googled the Travel Queen round tops and boy howdy some of the older vintage ones are pretty cool; a lot like Dave's Call Me Crazy build.

[OP827]

I get it too Michael, that is one cool experience, and thanks for sharing that.
BTW, I could not read the B.Rutan book as Tony's link would not download for me. Can Tony or you, KC help somehow email that or share otherwise?
I find that recomendation unusual to have a layer of 50-50 mix under the FG skin, which I can only explain by having interim layer of more dense substrate to make the sandwich work better? I don't know, but would really like to read this book. Thanks and cheers!

EDIT: it seems to download, but very very slow, so maybe I'll get it, sorry for asking, will let you know in this post edit again. - Got it downloaded and now reading it, thanks!

[KCStudly]

I'm thinking the micro slurry is to insure that there are no air pockets between the first ply and any roughly sanded areas of foam that the glass might otherwise want to bridge across with incomplete saturation. I'm thinking this is added insurance against voids or bubbles, and is lighter than if filled with straight epoxy.

I will consult with Karl on this one. Maybe Atomic can comment as well?

[Atomic77]

KC you are right on the money. This is a technique we use on the regular. There may be other reasons for this particular method but what you've described is what we recently did in San Diego on a repair where the rear corner of the boat was ripped off in a heat. We rebuilt it in the pits with foam and carbon fiber cloth. We use Aerosil or ground cotton to thicken.

[wagondude]

Ok, I misunderstood. I thought you were going to clamp the canvas in the gap between the hatch and spar. You probably won't have any trouble with how you are describing it. Incidentally, I got to see Mr. Rutan speak at an assembly when I worked for the company that made the instrument package for the plane he flew around the world. I wish I had even a quarter of his intelligence.