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Old Jan 10, 2013, 11:15 AM
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I've stood in the exact same spot at the Air and Space museum looking at this unusual aircraft. Cool project,
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Old Jan 10, 2013, 12:10 PM
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I pulled the tape off the fuselage and started to prep it for coating with Styrospray 1000. I always enjoy this step. Removing the tape is like unwrapping a gift.

The film on the FFF comes off with the tape and actually makes the tape removal process easier than tape over bare foam. The tape comes off in one piece per side like a snake shedding it's skin.

I've started to block sand out the ripples in the FFF. Not really ripples so much as thin spots if the FFF. Depron is more uniform in thickness but is hard to find in the 4 ft lengths I needed for this project. One of these days I'll have to order a case of MPF.

I had planned to use a solid block for the nose but the nose came out better than expected. I had to cut darts out of the foam to get it to conform to the mold and most of them closed up nicely. A small amount of filler and I should be good to go.

I'm going to use Styrospray 1000 to cover the fuselage and nacelles and may try it on the wings as well. WOWplanes.com makes extensive use of this material (they sell it as "LS II"). I used it on areas of my D0-335 and Beech D-18 and it has held up well. It's especially good for covering areas that are difficult with fiberglass or paper. In my experience, 3 light coats is equivalent to 3/4 oz. glass and WBPU in terms of weight, strength, and dent resistance.

BTW I've ordered a 2 quart kit which is probably enough for 8 planes of this size. I'll be splitting in up into smaller bottles and would like to sell some of it off, basically at my cost. It has a limited shelf life and I'll never use all of it before it goes bad. PM me if interested.
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Old Jan 10, 2013, 12:16 PM
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Originally Posted by Steve Merrill View Post
I've stood in the exact same spot at the Air and Space museum looking at this unusual aircraft. Cool project,
Udvar Hazy is an awesome museum. Come to think of it, most of my last several builds were inspired by planes I saw at that facility.
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Old Jan 10, 2013, 12:29 PM
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That could be used to make a glass fuselage easy enough also. I like the idea. I have to study your technique a little closer. I have to learn more about the Styrospray 1000 when I get some time later.
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Old Jan 10, 2013, 02:06 PM
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I have used this type of form to make fiberglass parts. See here: http://www.rcgroups.com/forums/showp...&postcount=46.. Using the heat shrink plastic to protect the form and over the fiberglass itself to give a smooth finish works REALLY well. You could of course, use the same technique to make a whole fiberglass fuselage. I didn't do that because solid fiberglass tends to weight significantly more. A fiberglass fuse doesn't dent like foam though.

I haven't decided if I'll use formed foam or molded glass for the nacelles. If I make the nacelles out of foam I can hot wire the wing cutouts which will make fitting them much easier. It depends how I do the electricals in the wing. Right now I'm planning to have the ESCs in the fuselage, aileron servos in the outer wing panels and Styrospray the nacelles to the wing center section all in one piece. Plan B would be to put the ESCs and aileron servos in the nacelles (along with flap servos and linkage if I decide to do flaps) and make the lower half of the nacelle removable. In that case I'd make at least the lower half of the nacelle from fiberglass and make it removable.

I originally planned a fast, simple build but things change as you go along.
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Old Jan 10, 2013, 02:31 PM
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Very nice.

The "Tape & Oven" method is very interesting and I plan on reading the related threads to learn what I can about it. I recently constucted both H & V stabs for a B717 I'm building and used a method that may work for you.

My build is a Dollar Tree Foam project. The material is about 5mm thick papered and 3.5mm when both sides of the foam board are stripped. I did a 5 layer lamination, 3 of foam and 2 of 1/16" balsa. I stripped the paper from the inside layer of each outer skin sheet and sandwiched the balsa alternately. This provided enough room for a wiring channel up through the V-stab as well as plenty of thickness for contouring. Its a simple method that works well for me and may be an applicable technique for you.


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Old Jan 10, 2013, 05:17 PM
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Udvar Hazy is an awesome museum. Come to think of it, most of my last several builds were inspired by planes I saw at that facility.
Me too. Someday I'll build that P-Shooter they have in there, or the Monocoupe!
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Old Jan 10, 2013, 05:45 PM
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The "Tape & Oven" method is very interesting and I plan on reading the related threads to learn what I can about it. I recently constucted both H & V stabs for a B717 I'm building and used a method that may work for you.

My build is a Dollar Tree Foam project. The material is about 5mm thick papered and 3.5mm when both sides of the foam board are stripped. I did a 5 layer lamination, 3 of foam and 2 of 1/16" balsa. I stripped the paper from the inside layer of each outer skin sheet and sandwiched the balsa alternately. This provided enough room for a wiring channel up through the V-stab as well as plenty of thickness for contouring. Its a simple method that works well for me and may be an applicable technique for you.



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Looks like a good way to do a T tail. I did something similar for my Beech D-18 to bury the rudder cables in the stabilizer. Just a single layer of 1/16" balsa in the center. The 219 rudders are kinda like a T-tail laying on it's side - there are 2 movable surfaces with a stationary piece between. I'd like to have some way to adjust the right and left sides independently of each other. I think I've got it figured out, just have to build it.

Very familiar with $tree foam! Just picked up more the other day. A very nice batch too - fewer ripples than normal.
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Old Jan 10, 2013, 06:06 PM
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Independent adjustment or trim or both?

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I'd like to have some way to adjust the right and left sides independently of each other. I think I've got it figured out, just have to build it.
Well, naturally the easiest and perhaps the only solution if you are talking about electronic adjustment, is to go with dual servo's on linked channels. Otherwise you can use the old reliable ez-connectors with thumbscrew turns. Personally, I don't like doing adjustments manually so I tend to go overboard with channels and servos which permits me to do the initial manual setup and then hopefully never have to fool with it again outside of the radio. (best laid plans....)
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Old Jan 11, 2013, 12:28 PM
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Well, naturally the easiest and perhaps the only solution if you are talking about electronic adjustment, is to go with dual servo's on linked channels. Otherwise you can use the old reliable ez-connectors with thumbscrew turns. Personally, I don't like doing adjustments manually so I tend to go overboard with channels and servos which permits me to do the initial manual setup and then hopefully never have to fool with it again outside of the radio. (best laid plans....)
I don't need to adjust each rudder on the fly. It's nice to be able add a little toe in or toe out on the twin rudders or just make them easier to zero out during assembly.

I spent some time last night on the linkage and got it sorted out.
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Old Jan 13, 2013, 10:41 PM
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Got to work on the tail section. The rudders on the 219 are split and the stabilizer runs right through. This complicates their construction a bit as well as the linkage.

First I cut the rudder outline from 2" foam and sliced it into 5/16" sections. I needed four and got a few spares too. Between the two foam layers I added 1/32" balsa around the perimeter. This gives a nice center line reference while shaping them, will provide some dent resistance to the edge, and some stiffness to the rudder. It also provides a stronger joint when I glue them to the stabilizer.

After the rudder blank was glued up, I traced the stabilizer on to the rudder and cut down to the balsa center layer on one side. After shaping the rudder, I picked out the foam where it will mount to the stabilizer. This not only makes a stronger joint but makes glue up easier because the stabilizer will plug into the recess cut into the rudder, keeping it aligned properly. Part of the recess will be cut all the way through for the part of the stabilizer that runs though the rudder.
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Old Jan 13, 2013, 10:53 PM
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The stabilizer was hot wire cut from EPS and sheeted with 1/32 balsa. Channels for the Sullivan S507 flexible pushrods were melted in place with the tip of a soldering iron. Tape at the ends keeps the gorilla glue out of the sleeves. I thought about doing a built up and sheeted stabilizer but this is easier and the weight of the foam core is negligible on such a thin section.
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Old Jan 13, 2013, 11:25 PM
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The rudder linkage took a little head scratching to figure out. I had originally planned to do the linkage similar to the way I did it on my Beech D-18; with adjustable clevises at either end. But that would have left a lot of linkage hanging in the breeze so I came up with this:

At the rudder I'll use a simple Z bend and horn. By pre-tinning the S507 cable with solder I was able to put in the Z bend without unraveling the cable. To make the connection at the center bellcrank adjustable I offset the two cables. I'll have to offset the rudder horns to match.

The bellcrank has to accommodate the rudder cable adjusters which are below the level of the skin and have the control cable connection above the skin. I took two servo arms and drilled them for a 5/32" brass tube bushing. I slid them onto the tube, slathered epoxy into the splines of the servo arms and pushed them together. The arms are further tied to each other with some fine stainless wire (guitar string.)

The bellcrank will be mounted with plywood plates above and below with a pin through the bushing.

The photo shows it's position in the stabilizer. Part of the reason to this resort to this somewhat elaborate setup was the decision to use Styrospray for the finish. I'll need to prefinish the parts and then assemble them. Styrospray is tough to keep out hinges and linkage.
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Old Jan 14, 2013, 12:09 AM
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I did a similar setup on my 10 foot Martin Mars rudders. It was a pain getting them setup. But I finally did get them swinging. I never resolved the arc on rudders exactly. Each rudder swinging outboard always swung out more than the other opposite inboard swinging rudder. The main anchor pivot screw was succeptable to slop. But I think I ended up fine with the belcrank and cable system. If I have any problems down the road I can put 2 servos in the elevator for the rudders due to the large size on my elevator. On a plane of your size you can't probably add servos unless maybe micros. Very nice work.
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Old Jan 14, 2013, 12:38 PM
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I'm not sure it would make much difference if the rudders swung more one way than the other.

A 10 ft Mars Martin!!! I wouldn't have a place to store it much less fly it. I'll bet it's impressive.

Multiple rudders at any size are kind of a pain but the twins I've made with twin rudders seem to handle better (on take off especially) than the ones with a single rudder.

I might have buried a single servo in the tail for the rudders and used the same offset cables but the dihedral on the tail meant the elevator pushrod had to run down the center and there just wasn't room to offset the rudder servo enough to make it fit.
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