Real Ira's "Shot Getter" - RC Groups
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Mar 23, 2007, 08:42 PM
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Build Log

Real Ira's "Shot Getter"


Shot Getter Build thread

This will be my build log for my version of Real Ira's Shot Getter. I was waiting for Doug at Mountain Models to come out with his new AP ship, but it appears that project has been shelved. So I figured it was about time to get my feet wet and do a scratch build. I'm a slow builder, so this will probably take many months. Heck it's taken me about three weeks of fooling around on the computer to come up with the design in a CAD package.

First, a disclaimer. Read Ira's Shot Getter thread in its entirety first! Ira has decades more experience than I have in building and designing aircraft, the original design is his, and he has been steadily refining and improving the design over time based on real-world flying experience. I am making quite a few modifications from the original Getter design to suit my own requirements, building style, availability of materials and components, etc. etc. which may or may not be improvements over the original. If you wish to incorporate any of the changes I am making here, you do so at your own discretion and risk.

List of Materials

I am building this list as I go along, so obviously it is not comprehensive (yet).

[table 1 3 1]
2^Qty.|Item/Material|Size|Notes
2|White foam|2" x 12"x 32"|Foam wing blanks
1|White foam|2" x 24"x 2 1/8"|Foam for fuselage
2|Aircraft grade plywood|3/32" x 12" x 6"|Fuselage sides etc.
1|CF Rod|1/4" OD, 3/32" ID x 36"|For fuselage boom
2|CF arrows|~5/16" dia. x 30"|For wing braces
4|Threaded inserts||For above arrows
1|Carbon fiber landing gear|-|-
2|3" lite foam wheels|-|-
1|6mm Depron Sheet|19" x 12"|For tail feathers
1|Gold-N-Rod pushrod set||Sullivan #503
1|music wire|5/16"|For wing joiners
1|music wire|3/32"|For tail skid
[/table]



The Build

OK, enough of the preliminaries. Let's cut some foam!

As I don't relish the idea of "hogging out" the channels from the foam after the fact, I made up a 2-foot length of "U-channel stock". This consists of a 24" length of 2" foam with a 3/4" x 1 1/4" block removed from the surface. This was done with my trusty 36" hot-wire cutter, which I described in my blog on wing cutting.

First, as the surface of the block wasn't very smooth, I cut it off clean with the hot-wire. I placed two clamps on either end of the block, and luckily the backs of the clamps were nice and smooth, so I was able to use them as guides for the wire. This left me with a fairly flat surface on the side of the foam.

I next made up some templates as shown in figures 1 and 2, below. Note that the lead-in broke off one of the templates as I was filing it. Didn't matter -- it became the "lead-out" and I used the other side to lead the wire into the foam. I used the floor panels that I had tried for the wing airfoil templates. They turned out not to be good for the wing templates, but worked just fine here.

Note: This was actually my second attempt at this. On the first attempt, I discovered, after the cut, that the foam had a bad warp in it, so the cut veered off to the side in the middle. For my second try, as shown in the pics, I was able to clamp it with the built-in clamps on a workbench I had around, thus straightening the foam for the cut. If you try this yourself, you might check your foam for warps before cutting, and clamp it somehow during the cut.

I also learned something interesting: the 2" white foam I bought at the Home Depot is not exactly 2" thick. It varies between about 1 29/31" to 1 15/16". This will affect the dimensions of some of the pieces as I was assuming the foam was exactly 2" thick.

More later.

-- Kevin
Last edited by Cats Eyes; Apr 03, 2007 at 08:20 PM. Reason: Updated List of Materials
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Mar 24, 2007, 09:15 PM
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I got the foam pieces cut out yesterday. Here are a couple of pics. All the pieces were made from the "U-channel stock" except the round nose piece, which was just cut from 2" foam.

I also got the 3/32" ply sides cut out (no pics). I'm gluing the foam onto the sides as I write this.
Mar 30, 2007, 10:19 AM
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The fuselage is coming along nicely.

I reinforced the front part of the fuselage, which will house the battery, with nylon banding (such as comes with the Magpie kits). I'm going to 'glass it as well, but will probably use very light fiberglass (3/4 oz/yd▓ as that's what I have floating around and am too cheap to buy more), so the banding will give it some added strength.

The ply hardware for mounting the boom and camera tray are shown in Fig 3. This is my usual tongue-and-groove fitting style, glued up with epoxy. Also note the bands of .010" aluminum (3/8" x 1 1/4" strips) to hold down the boom. This is new stuff for me, and I find it works very well for very little weight.

I installed a 6-32 "blind nut" in the front camera tray mount and filed off the ends of the "pins" that were sticking through. The camera tray will "hang" on the shaft part of the blind nut and swing freely. The screw will just act as a retainer.

The rear camera tray mount was extended and will become the servo rails for the tilt servo. The servo will turn a sprocket and chain arrangement to turn the camera tray through 180║. I "pre-installed" a 1/4" nylon screw, as there would be no way to get it in later without cutting through foam. This will have a second sprocket attached and hold/turn the camera tray. It's a 2" long screw, but will be cut shorter later.

Also, I updated the list of materials at the top of this thread. It's still not complete, but better than it was.

Next up: tail feathers.
Apr 03, 2007, 08:18 PM
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Starting to look a bit like a plane!


I got the tail feathers and landing gear finished. The rudder and elevator haven't been hinged yet, but I couldn't resist attaching them with packing tape and throwing the whole thing together for a "photo shoot". Hey, this is actually looking a bit like a plane!

The tail feathers are in three pieces. The fuselage boom is inserted into a ply assembly that holds the other pieces. The boom is held down by 1 1/4" x 3/8" pieces of aluminum (.010" thick) and 4-40 flat head screws (see figure 2, 3 and 5). This is quite strong and is unlikely to break or pull out, but it can rotate if forced. If this proves to be a problem, I will epoxy it in place as well.

The vertical stab is glued permanently to the ply assembly. The horizontal stab will be attached at the field using 1/4" nylon screws. The screws go through the assembly, through the horizontal stab, and through the tail skid assembly, holding all three together like a sandwich. I may glue the horizontal stab to the tail skid later if there is too much "play".

The tail skid is a 3/32" piece of music wire. This is bent with a sharp hook at the top and a corresponding slot is cut in a piece of 3/32" plywood (sorry, I didn't get a pic of this). I put 1/64" plywood outside of this and slathered the whole thing with epoxy (figure 6). The 3/32" plywood mentioned is attached to the plate with the holes for the 1/4" screws. Note I've glued a dowel "button" into the horizontal stab to transmit the "blow" from a hard landing up through the stab, to avoid crushing the Depron of the stab itself (see Figure 4).

Next, I'll tackle the wings...
Apr 10, 2007, 08:46 AM
Registered User
Looks great!
It's inspired me to start such a project as soon as I finish a scale plane.
Again great job let us all know if you put enough power on it because the E-Motor thing is somewhat new to me.
Apr 11, 2007, 11:24 AM
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Thanks, glad it's inspired someone. Be sure to read Ira's thread!

Still hemming and hawing about the power. Thing to remember is this is not an aerobatic ship, just supposed to fly slow and stable. Ira's using an AXI 2808/24. Motocalc also seems to think that would be good for a plane like this. But I'm a lousy pilot so I like some reserve power to get me out of trouble. I have a 2808 on my MagpieAP and it's more than enough power for the 'pie, but this is a larger plane, so I don't know...

Good luck with it!

-- Kevin

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