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Old Jul 03, 2012, 03:02 PM
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Build Log
HZ Champ to Birddog Kit Bash

Its been a while since I built an airplane, and I have NEVER worked in foam before but, OK ya talked me into it.

When I first saw the u/m HZ Champ, the very first thing I noticed was the number of other a/c it could be turned into. A little filling, a little trimming, a little sanding and the Champ could be almost ANYTHING. But first I had to learn to fly R/C. Id been trying off and on for YEARS to learn how and the Champ served the purpose. I aint the Ace of the Base but after a month or so, Im doing pretty good. While I was learning I destroyed a wing and tweaked the fuselage good a couple times. Last week the elevator tore in half. I bought a couple spare wings and I just got a replacement tail and then I found a whole replacement fuselage WITH motor, brick and servos for like $10.00. So now I have a new Champ to continue to learn to fly with and an older Champ to get me back into one of my first loves building airplanes.

Since I found this web forum I have been reading myself cross-eyed catching up on what has been going on since I left the hobby about 15 years ago. Folks here are very kind in helping NUBEs here and this is a GREAT place to learn. There is a WORLD of info on this site it is WAY better than ANY magazine.

CREDS WHERE CREDS ARE DUE: While doing this project I have been greatly helped by the threads and posts relative to (among others) gkleins AT6 build (in progress) and Speedy and mtflyrs build threads. If stealing building techniques were a felony Id get the electric chair. Thanks guys!

Anyoldways this is proving to be a VERY easy project. I printed out some plans and three views of both the Champ and the L19 Birddog. I laid one on the other and drew a couple lines on the Champ. I stripped down a Champ fuselage, and transferred those lines onto it and started cutting on my bandsaw. Then I took some cooler foam marked out what I needed to fill in the fuselage and cut it out. Youll see that I needed two pieces. The smaller on glues onto the bigger on and forms the area that will be the rear window of the Birddog.

Ive done a couple experiments with Gorilla Glue to see if it would fill voids and give a good sandable surface. It does so Ive used it to glue the foam blocks in. Notice the pins as clamps? Theyre a throw back to my old balsa stick plane building. Once the gorilla glue expanded and cured, I started trimming and sanding away everything that I didnt need to build a Birddog. Ive got the rough shaping done and Im beginning to think this project just might fly.

The tail feathers will come from foam plates that Im flattening in the oven even as we speak. Im going to use one of my spare Champ wings. Because the Birddogs wing is aluminum, Ill sand the ribs off a Champ wing and reshape it as necessary.

Yes ... I know the Champ's nose is a little stumpy compared to the L-19 ... but its close enough for government work.

More to come.

Keep on building.
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Old Jul 03, 2012, 03:11 PM
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Here's the foam filler blocks ... I guess I could have just cut away the parts of the fuselage I didn't want , and cover over the holes with 1mm depron ... and saved some weight. But I didn't have the depron ... and wanted the support of a block of foam under the back part of the wing. I'm still learning to fly and this bird is gonna take some lumps and bumps. I can use a Dremel tool to hog out some of the foam I don't want.

You will see a total of 4 layout lines on my foam block ... I held the Champ fuselage onto the block and used it to scribe lines along the outside ... then i measured the thickness of the Champ fuse ... and scribed them on the foam ... those are the inside lines and they are the ones I used to cut and fit my block into the Champ fuse.
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Old Jul 03, 2012, 03:19 PM
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The part of this project that is taking the most time is waiting for the Gorilla Glue to cure.

anyoldways ... hacking, cutting, grinding, sanding ... now my shop is filled with foam dust ... and I got a rough shape done.

Now I'll set in finish up the shaping and to wet sand all that pretty yellow paint off.

I got about a gallon of Army green paint left over from when I painted my faithful ol' Govm't Mule, Henry. It should do just fine on this here Birddog.
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Old Jul 03, 2012, 04:43 PM
So broke I can't pay attention
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I was considering doing a Birddog, but opted for an L-16.
Looks great so far, can't wait to see it when it's done
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Old Jul 03, 2012, 04:46 PM
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I hope this .pdf file shows up ...

soanyoldways ... I got a question about cuttin' down the champ wing for all you guys who know what they're doing.

The middle 1/2 of the Birddog wing is shaped similar to that of the Champ ... having cross-section that is the same length.

However, the ends of the wings,l when view from above, taper inwards, resulting in a decreasing cross section ... this taper starts about mid-wing and continues to the tip.

If I change the Champ's wing to reflect that shape ... how is it going to impact the performance of the wing?

Does anybody have any guesses?

I guess I should just go to Home Depot and get some foam, cut it down with a foam slicer ... cook tit to an airfoil shape ... and give it a try. But they're closed tomorrow.
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Old Jul 03, 2012, 04:49 PM
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Quote:
Originally Posted by caymin last View Post
I was considering doing a Birddog, but opted for an L-16.
Looks great so far, can't wait to see it when it's done
I think saw your L-16. Thanks for the reminder ... you'll be named as a co-respondent in the divorce action.

Hey ... we're dealing with little under-powered bug smashers. A little OD paint ... and they're all the same!
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Old Jul 03, 2012, 05:21 PM
So broke I can't pay attention
Naples FL USA
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Thanks oddshot, LOL!
Maybe an Ember Wing might be better to shape/trim to match the Birddog, just a thought.
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Old Jul 03, 2012, 07:40 PM
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looks good oddshot! this should be neat.
just test your paint on some scrap foam to make sure it dosn't eat it. i been there before
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Old Jul 03, 2012, 08:44 PM
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Originally Posted by meltor View Post
looks good oddshot! this should be neat.
just test your paint on some scrap foam to make sure it dosn't eat it. i been there before
ain't gonna happen bud ... this here is ARMY (Home Depot house) paint!

It didn't hurt my mule none.
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Old Jul 04, 2012, 09:07 AM
So broke I can't pay attention
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Here is a link to the thread on posted "scale Decals" I used.
http://www.rcgroups.com/forums/showthread.php?t=359029
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Old Jul 04, 2012, 09:19 AM
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Quote:
Originally Posted by oddshot View Post
I guess I should just go to Home Depot and get some foam, cut it down with a foam slicer ... cook tit to an airfoil shape ... and give it a try. But they're closed tomorrow.
Lowes should have Fan Fold, which might be easier to shape into a wing.

I think they are both open on the 4th, too.
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Old Jul 11, 2012, 01:59 PM
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Ive been busy with work over the past days, but Ive been chipping away at the Champ /OE-1 Birddog (USMC version of the L 19) where I can.

Ive stripped the paint using 91% rubbing alcohol, and Ive lightly rubbed lightweight spackle into the small hole, sanding marks and etc so the plane will have a smooth surface. Back in the stick and paper model days, we would use a balsa sanding filler for this purpose. I intend to brush on a couple of light coats of Minwax Polycrylic and will sand everything lightly before painting.

In hindsight, I wish I had weighed everything before I removed the paint from the Champ my guess is that the original paint job is VERY heavy compared with the filling and painting I will be doing, but it would have been nice to know. Since I have another Champ, I can do weight comparisons when Im done.

Im reminded from my car racing days that Colin Chapman of Lotus fame once said, Build Lightness In. Chapman was VERY conscious of the idea that its easier to BUILD LIGHT, rather than try to take weight OFF when everything is built.

When flying my champ, I have found that its VERY sensitive to too much weight in the tail. That being said, I have ground out the bottom of the foam filler piece I installed in the top fuse to a thickness similar to the original fuse. I know that I've left a bit of foam at the extreme rear, I intend to use this to hold a bit of a toothpick that I can use as a hold down pin. This will be lighter than a magnet, just as strong, and a lot less ugly than the tape that was back there.

For those who would like to take a little weight out of the tail of a Champ, I think I have found a good spot The rear of the fuselage under the tail feathers is solid foam. Carefully drilling a couple holes back there shouldnt weaken thing much, and might just even out a c/g problem without adding weight to the nose.
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Old Jul 11, 2012, 02:14 PM
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The Champs nose got flattened and dinged a bit during learning to fly, The easiest way to repair the tops section seemed to be , cut out the old, and splice in a new piece. Once hard, it will get trimmed and sanded to shape.

Also, the space in the lower section of the fuse between the motor and the receiver was a bit ... compressed. I've taken a bit of thin, lightweight ply, cut it to shape and will epoxy this to the inside of the sides of the fuselage. I'll drill a couple lightening holes in the plywood, which will also allow the epoxy to flow through and give a stronger bond.

I've cut out empinage (!!!) out of some pie-plate foam using the pattern I found on a couple Birddog stick model plans
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Old Jul 11, 2012, 02:23 PM
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I have decided to paint this Birddog to replicate one of the OE-1's flown by USMC Aviators during the Vietnam War, and will be using markings from VMO-6 known variously as Cherry 6 or The Tom Catters. While doing research for this project (which is sometimes the very best part) I have found the below pictures.

For some folks part of the thrill of a Carrier launch is the blinding speed, others get a buzz from the crushing G forces of the cat shot. But some Aviators get a kick out of hearing the applause of the deck crew when the dang thing survives falling into the air, as seen below.

The next picture is of a Pilot and his mighty war-bird who could put more hurt on a patch of ground than any other single pilot in the skys over Vietnam.

The last picture is of a OE-1 Birddog in VMO 6 livery flying here in the US.
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Old Jul 11, 2012, 02:48 PM
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The Birddog has ridges on the A, R, E, control surface that I suppose are their to provide stiffing to those surfaces or straighten out airflow over them ... none-the-less, the ridges are a fairly significant detail of the a/c and I would like to replicate them.

My best ideas are

1) cut very thin strips out of sticky-back label and install them pone at a time ...

or

2) use tape to mask out the shallows and fill in the detail with layers of paint.

I'm leaning towards number one.

Anybody else have anything?
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