Giant Foamie Home Depot YF-22 - Page 63 - RC Groups
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Feb 01, 2013, 12:02 AM
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Update on our team build.

First let me say that if you have never built a flat plate foam airplane with a cabinet maker you are really missing out. A full shop of amazing tools and capabilities combined with more attention to detail than I have ever had has made this a fantastic experience!

When Mark cuts foam with a blade and guide jig it peels thin and transparent not unlike a master sushi chef working on a hunk of Yellowfin Tuna! All the tab slots, tabs, vertical fins and sides have the 20 degree angle cut into them! When the airplane is assembled, it goes together with the proper angles built into the sides and fins and is completely gap free. Virtually no additional fitting or filling required so far! The plan is to use a router to shape the leading edge!

We are currently engineering the skeleton box. Will post updates when we get there.

We are thinking about modding the design a little. We have six 4s 3000 packs laying around so we will use them. Between the blue foam, the 3000 packs and the desire to put the servos all the way in the tail, we are worried about the CG. being too far aft. We saw a mod on this thread where a guy made a 3d nose section. The 3d nose section would allow a ton of variance in the location of the battery location to get the CG right on without having the servos up front or adding nose weight. We could run a variety of batteries in the future and it would just look better in our opinion. This will require a little modding of the skeleton box to beef up the nose section. The coolest part will be running the 1/2 foam throught the planer to get just the right amount of thickness and pliability for this mod. Stay tuned for development!

Click on the pics for expanded dialogue. Enjoy!

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Description: Birdofplay templates printed at Office Max and transfered to posterboard.

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Description: Layout of parts on a sheet of blue foam.  Two complete airplanes can be cut from one sheet.  The planform was layed out as one continuous piece.  Be sure to extend the tabs to the thickness of the foam.

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Description: The channel for the carbon spar was routed into the foam at half thickness.  The router guide is shown in the photo.  Installing the spar this way allows the planform to remain one piece and keeps a continuous foam leading edge.  Since the spar does not g

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Description: Three kits are ready for assembly.

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Description: This is the guide that allows all of the angles to be cut true throughout the build.  A long, sharp blade rides against the angle and into the foam.  All tab slots, tabs, bottom of vertical fins and the bottom side pieces were cut usng this template.  The

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Description: A picture of the vertical in the angled tab slot before glue applied.  That joint is gap free!
Last edited by flyingfitz737; Feb 01, 2013 at 12:12 AM.
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Feb 01, 2013, 12:08 AM
Feb 01, 2013, 04:33 AM
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dbacon's Avatar
Personally I don't like to add weight to get it to balance, so if you are adding the extra nose to allow servos to exist near the tail, how about pull-pull cables with the servos up nearer to the CG? They are easy to make, never bow under stress, and can be very light, especially if you use Kevlar.

2/26 edit, now I see you are adding the nose to allow the battery to move further forward - good idea!

I use 10-30 pound fishing leader material just because it is easily available, and I can crimp 2-56 threaded tubing ends to it from DuBro, and Sullivan clevises. With my foamies, I just loop the ends through the hole in the servo arm and fasten it in one of several ways. Using a tiny screw is probably the easiest, but I keep experimenting. On the control surface I use a stick through it, with a foam gusset glued to it for stability and permanently attach the cable to the end of the stick, top & bottom. My Capricorn is less than two pounds, so the stick is just a toothpick. I finally received my lightweight horns from HobbyKing, and I think the next project will get two of them per control surface.
Last edited by dbacon; Feb 26, 2013 at 11:03 PM.
Feb 26, 2013, 10:24 PM
Registered User
Originally Posted by diggerrcdave
Here's a picture of mine if I can get it to download.1st time for a picture.
That is a really beautiful plane. How did you do the paint job?
Feb 27, 2013, 12:03 PM
Retired CAD guy
birdofplay's Avatar
I've been having good luck with KEVLAR threads Pull Pull cables.
Threadexchange has lots of spools of the stuff.
Feb 27, 2013, 12:44 PM
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dbacon's Avatar
I thank you. I ordered two 90 yard spools of 14 lb for $6, way better than that kite string I bought long ago.
Feb 27, 2013, 03:39 PM
Retired CAD guy
birdofplay's Avatar
14# will probably do but keep checking for fraying if there is a rub point.

It's so light that I would have thought you'd go a bit higher in tensile strength.

I've used it on my FalCLONE 56 since last spring for TRAINING another guy.
Rudder and elevator.
Still looks ok.

Be sure you leave yourself a way to retention as temperature makes models grow and contract. At least My Foamy does.
Feb 27, 2013, 04:41 PM
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dbacon's Avatar

I an thinking of just using it on my foamies which would weigh less than a couple pounds anyway. I did try Kevlar on one of my nitro planes a while ago, to replace the fishing leader which is vinyl covered steel, but the fraying problem frightened me.

I would use a threaded brass tube from Sullivan (I think) that screws into a Sullivan clevis, and I lock it from spinning with a tiny 2-56 nut as a jam nut. But crimping the brass tube on the Kevlar seemed a little brutal, and I didn't like the stress point where the Kevlar exited the end of the tube.

With the foamies, I just tie it into the plastic horn on each end, and if it needs trimming, I can just re-tie it. Not very clever, but seems adequate. My foamies don't seem to need trimming, at least beyond the range of the trimmer slider on the TX, so I get away with just tieing it to the horn.

As far a temperature changes, if it gets slack I will become worried, and have to think up something, but the lengths are short, and they are usually a little bit slack anyway, doesn't seem to bother, as long as it is not sloppy at the center. I purposely setup the geometry to go slack as you deviate from center, by having the control surface attachment point slightly in front of the hinge line. This takes all the stress off when you deflect the surface, and keeps me from having to worry about precision geometry, which causes a few over-thinkers to proclaim that my system will never work.

Lots of things will never work, like wings with no airfoil and car tires that are larger diameter than stock. I just ignore that. Throw global warming in there too.
Feb 27, 2013, 09:55 PM
Retired CAD guy
birdofplay's Avatar
Whatever :-)))

I used HOTMELT to FIX them to horns and remelt to tighten.

Kevlar doesn't stretch ! so it's gotta be the plane or "whatever".

I have not figured an elegant way to do it just yet either.
Feb 27, 2013, 11:06 PM
Registered User
dbacon's Avatar

Thanks the hot melt sounds like a good thing to try. I think I would thread it through a short tube as it went back to the control horn, loop through the horn, and double it back through the tube again. The tube would have hot melt in it. Then I could just warm the tube and adjust it.
Feb 28, 2013, 10:12 AM
Retired CAD guy
birdofplay's Avatar
Hey I like that !

I'd just weaved it thru the Servo arm holes and hot melted on there.
Leaving a thread to grab for tightening.

Whatever :-)
Mar 03, 2013, 02:18 AM
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dbacon's Avatar
Nice to know that the hot glue is that strong, thanks.
Mar 03, 2013, 09:55 AM
Retired CAD guy
birdofplay's Avatar
Part of the functionality is that Kevlar is pretty abrasive so it doesnt slide easily.
Two The weave into the Servo arms helps tremendously and the Glue just keeps it in place.

When flying Kits with Kevlar Versus Spectra
1. the Kevlar. when the kite was wound up doing loops. would become uncontrollable at about 4 loops
as it couldn't EVEN slide against ITSELF !
2. When two kite lines meet, Kevlar Vs Spectra, the Kevlar WINS and the Spectra gets CUT instantly !
Mar 08, 2013, 10:32 PM
Registered User
A few more build pics.

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Last edited by flyingfitz737; Mar 18, 2013 at 09:10 PM.
Mar 08, 2013, 10:41 PM
Registered User
Team Build Complete!

The planes turned out awesome. Will have more build photos posted above. Here are some shots from maiden day. Video will soon follow. Enjoy!

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