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Sep 11, 2004, 04:25 PM
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P. Tritle's Avatar
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Waco SRE for IPS Power


After working with Charlie trimming his Peter Rake Waco, I could see that the time had come to take the idea off the back burner and get going on the IPS powered Waco. This project has been at the top of my "things I gotta' do real soon" list for way too long, so here goes
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Sep 11, 2004, 04:35 PM
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The Original Idea Was For Geared S-280 Power ---BUT----


When the plans were roughed in, I thought that a 35" span model with 300 sq. in. of wing would be a bit much for IPS power, so the plans were drawn showing the mount for a geared S-280. But, once all the framing was done, the structure tipped the scale at only 2.5 oz, so it started looking like an IPS "A" or "B" drive might just get the job done using a 9" or 10" prop.
Sep 11, 2004, 04:38 PM
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The Tail Section


The outlines on the vertical and horizontal tails are bowed up using 1/16 x 1/8 balsa. The rest if the structure is mostly 1/16 x 1/8 and 1/8 sq. balsa with just a couple of shaped parts..
Sep 11, 2004, 04:49 PM
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The Wings


The wingtip bows are also laminated over forms. The top wing uses 2 lams of 1/16 X 3/16, the bottom bows are 2 lams 1/16 X 1/8 balsa. The main spars had to be modified slightly to accomodate the tip bows since the bows were too stiff to conform as originally layed out. Once again, the beauty of CAd is the ease of revision -- the more I use it, the better I like it
Anyhow, the top wing ribs are 1/16 sq. balsa bottoms with a shaped top section, and the whole thing diagonally braced with 1/16 sq. balsa. Don't let the seamingly small wood sizes scare you, it's a lot tougher then it looks, but doesn't weigh anything!
The bottom wing, due to its minimal size is done using full rib sections, but still going with the shaped main spar.
Sep 11, 2004, 04:56 PM
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The Fuselage Frame


The basic fuselage frame is layed out using 1/8 sq, balsa longerons with 1/16 X 1/8 vertical and diagonal bracing. No diagonals were used in the aft fuselage since there are 18 stringers glued in around all the vertical braces and provide more then adequate tortional rigidity.
The main gear strut is 1/16 wire with the bracing bent from .046 wire and slodered together.
Last edited by P. Tritle; Sep 11, 2004 at 05:09 PM.
Sep 11, 2004, 05:08 PM
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Servo Mounts


The servo mount beams are glued in place in the forward cabin to try an counter the chance of winding up tail heavy. Those Lipolies are great, but don't offer much in the way of CG shift. The Berg RX will velcro to a plate on the servo rails too.
Sep 11, 2004, 05:14 PM
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Mounting the Motor


As luck would have it, the motor mount is nothing more then a 1/16 balsa plate glued to the floor of the main fuselage frame. The GWS "B" drive was glued to the mount with silicone, offset 2 degrees to the right. It might bite me later, but no down thrust was put in. We'll have to see how that works out later.
And that's about it for now. There's a bit of detail sanding needed, then it's time to cover.
Stay tuned, PAT
Last edited by P. Tritle; Sep 11, 2004 at 05:20 PM.
Sep 11, 2004, 05:23 PM
Veni Vidi Volavi
Brian Allen's Avatar

Waco


Pat

Sweet!!!!!! I want one. As soon as I build the Mr MUlligan and Ercoupe that is. Any plans for plans, short kits etc? How about a YMF-3/5 or a UPF-7? Or a Model 9 or Model 10? Love them Waco's.

Brian Allen

Veni Vedi Volavi

I came I saw I flew
Sep 11, 2004, 05:39 PM
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Brian, Why an I not sirprized to see you stick your head in the door on this one And to answere your question, in a nutshell, is yes, but unfortunately, that's all I can say about that right now But don't worry, when it happens, you'll know it
PAT
Sep 11, 2004, 08:43 PM
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Brian Allen's Avatar

Waco Sre


Pat

Gee am I that predictable?? Keep us posted on the build etc. What are you going to cover it with? Litespan or similar or SOlite?

Brian Allen

Veni Vedi Volavi

I came I saw I flew
Sep 11, 2004, 09:31 PM
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Pat, do you sleep? How many of you are there? The bench hasn't even cooled down from the Bird Dog, and you've already designed and framed up another one. And not a simple design either! This project is looking great, love the spar and diagonal bracing in the wings. Can't wait to see the finished project.

Jim
Sep 12, 2004, 04:41 AM
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Pat,
Beautiful looking model. Puts my rather crude version to shame. I'll be watching this thread with interest.

Pete
Sep 12, 2004, 07:06 AM
Compliments from me too, Pat. Peter's model can't be as "crude" as my Luscombe's gonna be! I gayly (no! - straight up!) cut over twenty ribs for my wing from 3/32 instead of 1/16 last night.
Can't even read and obey my own plans!! Built the b...dy wing anyway - I'll lighten it later by buying another Lipo!!
Ade
Sep 12, 2004, 12:03 PM
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Brian, You're not so much "predictable", as much as a Waco lover can sometimes be really hard to hold back The plan is to cover the model with Litespan. I'll probably do it up in yellow trimmed in blue, and add the numbers with cut vinyl.

Jim, I tried sleeping once, didn't like it all that much seems that when I woke up I'd forgotten most of what I thought I knew Actually, due to the wizardry of CAD, and the magic of laser cutting, these type structures frame fairly fast.

Peter, Hey, you got nothin' to appologize for in your Waco at all. That is one of the coolest airplanes to grace our flying fields in a very long time What it lacks in "scale", it more then makes up for in "flies good", and in my book, "flies good" simply must come first -- you have a great formula, don't you dare change it

Ade, I know how that goes, I can hardly get through building my own sruff without changing something either. But with me, I would have probably gone the other way and cut the ribs in 1/20, then cussed at myself for half an hour trying to sand the wing while breaking everything in sight

Jim, You know, since I saw that wing design on the Dumas Mulligan I've been kicking myself in the kiester for not thinking it up myself, 10 years ago. It's so simple I just couldn't see it till somebody showed it to me. With the diagonal bracing, the wing is more resistant to twisting, and once the cover goes on the rigidity is more than adequate.
But, if you really want it stiff, add another set of 1/16 sq. diagonal braces running from the bottom spar/rib junction to the T.E./rib junction to form an "X" pattern. If you do though, make sure the washout is set when you add the bracing, cause you won't be able to twist it in after the fact. The weight penalty will be minimal, but the strength will be extreme.
PAT
Sep 12, 2004, 12:09 PM
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mu2freighter's Avatar
Pat, since you don't sleep anyway, and you clearly like WACOs, howzabout a UPF, YKS, and/or a Witchita Fokker while you're at it?

LOL

The SRE looks lovely, nice work as usual!

Glenn


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