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8 foot C123 Build

Old 12-02-2006, 05:02 AM
  #1  
rcav8r
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Default 8 foot C123 Build

I've always liked big lumbering cargo planes, and always thought about building one. Well with the advent of electric power, and after reading Keith Sparks Building w/ Foam book, I decided on the C123.
* It is only a twin, (purchasing 2 outrunners is cheaper than 4 )
* It's a rather obsure plane...i.e. not another B-25 or C130.
As an added bonus, after I started work on the drawings and gathering materials, I found out that there is one about 5 minutes from my work. I passed twice a day on the way to and from work.

Anyway here are some random pictures of the process so far. I'll post more details of the construction if there is interest.

Edit: Pics
1) 2) 3) 4) 5)
6) 7) 8) 9)
1) rough cad drawing of 3view
2) kids holding the fuse for size refernce
3) wing and stab blanks 2 foot ruler for size reference
4) Gluing blocks for the nose
5) sides of nose block rough sanded
6) Nose bottom view outline
7) Getting read to cut wing w/ home made drap bar foam cutter
8) Fuse mock up. Will split fuse middle and tail to make 2 one inch sides.
9) gluing fuse middle


Also, how do you add comments to pictures?
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Last edited by rcav8r; 12-02-2006 at 08:53 PM.
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Old 12-02-2006, 05:32 AM
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cyclops2
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Foam planes are fun.
Looking good.
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Old 12-02-2006, 02:14 PM
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Hey rc, thanks for posting the build photos of an unusual plane! I use a photo editing free program called IrfranView to edit my photos and add text the url is: http://www.irfanview.com/ Another thing folks do is just list the descriptions as a part of your post, most builders can figure out what you are taling about.
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Old 12-02-2006, 02:28 PM
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I'm in RC!

keep us posted on the build. I'm looking to do a Lockheed L-10 Electra so will be interested in your technique and process since I have never scratch built anything before.
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Old 12-02-2006, 05:29 PM
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Hey Buddy, where did you get those rotors? They look a little rusty.:p
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Old 12-02-2006, 08:24 PM
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Wow!! That thing looks cool. However it also looks heavy, how are you going to power it? Do you have a target weight for the project?

CTD
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Old 12-02-2006, 08:25 PM
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Originally Posted by airmail wf View Post
Hey Buddy, where did you get those rotors? They look a little rusty.:p
I'm in the process of seasoning them

Don; I'll check out the irfanview; thanks. For now I added some captions. I was expecting fields for captions next to the pics after they were downloaded. I guess this feature isn't there.

Anyway here are some pics of the full size one.
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Old 12-02-2006, 08:46 PM
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Originally Posted by Crash Test Dummy View Post
Wow!! That thing looks cool. However it also looks heavy, how are you going to power it? Do you have a target weight for the project?

CTD
I guess heavy is relative I'm for a AUW of 8-9#s. Even if it gets up to 10#; that isn't exactly heavy for an 8-foot warbird. Than again compared to my <3 ounce Diddle Bug; yea it's heavy
Nose alone is 12 ounces, but I'm sure I'll loose more than half of that once I carve/sand to shape and hollow out. Looking to power load it at about 75wats per # Not sure of the motors/props just yet. I'll decide once I get the wight of the empty airframe.
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Old 12-02-2006, 08:53 PM
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Originally Posted by firemanbill View Post
I'm in RC!

keep us posted on the build. I'm looking to do a Lockheed L-10 Electra so will be interested in your technique and process since I have never scratch built anything before.
Bill; This is my first all foam scratch build; so I don't know if I'm the best one to follow I do highly recommend the book "building with foam" by Keith Sparks. The book is basically an overview, and provides just enough info to get you started. You do have to fill in a lot of the blanks yourself, but that's half the fun.
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Old 12-02-2006, 09:07 PM
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Originally Posted by rcav8r View Post
I'm in the process of seasoning them .
I'm sure most people on this forum are wondering what the heck you are talking about. Make sure you use a little salt and pepper.:p

To stay on topic: I think this is going to be one heck of a plane. Make sure you let me know when you are going to maiden it. I'll bring my camera.
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Old 12-02-2006, 09:12 PM
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Originally Posted by rcav8r View Post
Bill; This is my first all foam scratch build; so I don't know if I'm the best one to follow I do highly recommend the book "building with foam" by Keith Sparks. The book is basically an overview, and provides just enough info to get you started. You do have to fill in a lot of the blanks yourself, but that's half the fun.
I should get a copy of that book! It looks like you are doing well so far.

I know what he meant WF! I've got a few old cars seasoning out back as well!:o
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Old 12-02-2006, 10:31 PM
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You will not exceed 1# / sq. ft, flying weight. If hollowed out to a safe wall thickness.
Remember 2X the wall thickness, is NOT 2X the weight. Leave in a GOOD safety factor for that unexpected dive and high speed pull up.

Most of us get 1 or 2 of those per airplane. It just happens.

Save a lot of tail weight by using pull-pull tail controls. 10# fishline. Long tail/short nose planes need nothing in the tail. 3 : 1 ratio means 2 oz. in the tail needs 6 oz. of battery hanging out of the nose.

Turboprop cargo plane wings bend my 1#/1 ft. load rule a little with their high eff. airfoils.
Does the 123 have a flat bottom? If yes, some of the area acts as lifting area.
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Old 12-03-2006, 02:35 AM
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In on this one. Very cool.
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Old 12-03-2006, 03:31 AM
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Hey, yeah, one of those came bumping through here a few months ago, and I was REALLY impressed that the old tug was still flying! I still have my copy of Air Trails with Cal Smith's painting on the cover....

Seems that there were some less-than-complementary names for it, referring to its unusually large nether regions...

Make 'er fly, rcav8er!
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Old 12-03-2006, 04:43 AM
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Wow nice going bud I will keep an eye on this one.

Tips
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Old 12-04-2006, 03:38 AM
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Since there seems to be some interest, here are some details on the various processes.

The nose of the C123 has compound curves with some sharp angles so I thought the best method would be to build it from blocks of 2" foam. Then carve/sand to shape.

1) 2) 3) 4) 5)
6) 7) 8) (8 should go between 3 and 4, but somehow the pics uploaded out of order)

1) Cut blocks that will make up the nose. Labeled and center lines marked
2) Test stacked and marked for vertical position, horizontal alignment
3) Just a spot of epoxy is needed as the parts will be separated and hollowed later.
4) Getting the side view to the blocks
5) Rough cut with hot wire. Careful here as the hot wire can easily get away from you when free hand cutting
6) Close enough for now with 80 grit sand paper
7) bottom view traced to blocks.
8) Keep plenty of weight on the stack while the epoxy cures. Be sure the blocks don't shift. The small spot of epoxy helps with this as there is not enough epoxy for the parts to slip on.
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Old 12-04-2006, 03:54 AM
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Originally Posted by Cyclops View Post
Remember 2X the wall thickness, is NOT 2X the weight. Leave in a GOOD safety factor for that unexpected dive and high speed pull up.
Most of us get 1 or 2 of those per airplane. It just happens.

Does the 123 have a flat bottom? If yes, some of the area acts as lifting area.
I'm guessing you mean 1/2 the thickness is less than 1/2 the strength??? Yep I took that into consideration... sides of fuse are 1inch.
For the wings. I'm going to go with 1/4" spruces spars top and bottom. The whole thing is going to be glassed adding to the strength. I'm hoping to be erroring on the "heavy" side.

Knowing my flying style I'm not going to promise that I won't roll the thing, but only after a few shake down flights ( hay I waited until the 2nd flight before rolling my 6 foot B29 ) and that is only after I see how the thing is holding up ( stress , flexing, etc) I'm guessing this is going to be basically a large funny looking powered glider.

As far as flat fuse bottom. Yep all 12+ inches worth is basically flat.

On the 3 view I have the tip/cord ratio is less than 2:1. I made mine a little more than 2:1 and have 2 degrees washout hoping to avoid tips stalls. Airfoil is a simple Clark-Y. Probably going to go with 2deg positive on the main wing, and 0 on the stab. Any thoughts on this?
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Old 12-04-2006, 07:04 AM
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[quote=rcav8r;123352]Knowing my flying style I'm not going to promise that I won't roll the thing, but only after a few shake down flights ( hay I waited until the 2nd flight before rolling my 6 foot B29 ) and that is only after I see how the thing is holding up ( stress , flexing, etc) I'm guessing this is going to be basically a large funny looking powered glider.

As far as flat fuse bottom. Yep all 12+ inches worth is basically flat.

/quote]
Large funny looking powered glider" well ain't that what they are.
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Old 12-04-2006, 03:00 PM
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AV8R.............You going to paint it or leave it pink?

Nice job so far!! Think you'll have it done for the electric fly at Cedar Creek?

Doug
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Old 12-04-2006, 05:14 PM
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rcav8r,

I like the pegboard idea you have in the back of your shop. I enjoy building large foam models too. Here is a link to a thread I did on an acrobatic style large scale model. It will be cool to watch how you do things and trade build ideas. I have a bunch of that size pink foam you are using, great stuff. Will you be hollowing out the nose section of the plane. What are the lanes dimentions going to be, and what is your expected AUW?

Page 1 shows 1st model and beginning of build- http://www.rcgroups.com/forums/showthread.php?t=450106

Page 2-11 shows rest of the build - http://www.rcgroups.com/forums/showt...6&page=2&pp=15


Page 12 here shows final pics -
http://www.rcgroups.com/forums/showt...&page=12&pp=15

Good luck yours is looking great,it's fun to work with foam!

Tips
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Old 12-05-2006, 03:04 AM
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Glad to see I'm not the only one that starts a new project when I have others still to complete
looks like that one will be pretty cool
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Old 12-05-2006, 05:38 AM
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Originally Posted by Unbalanced prop View Post
AV8R.............You going to paint it or leave it pink?

Nice job so far!! Think you'll have it done for the electric fly at Cedar Creek?

Doug
Yeaaaa. It'll be pink. Nice and easy to see if it goes down in the woods Seriously, I'm hoping to make it the same as the full scale one that I happen to have unlimited access to.

I really hope to have it done for the Cedar Creek Electric fun fly. Not sure if it will take off on the grass as the 3" wheels ( exact scale BTW ) sit at the bottom of the fuse for a whopping 1.5" of clearance. Did you hear Keith got permission to make it a multi day event? Will probably do a shameless plug here once I get more info. I'll be helping out Keith this year. Too bad it rained for the one this past summer. The others were a blast.

Originally Posted by skiman762 View Post
Glad to see I'm not the only one that starts a new project when I have others still to complete
looks like that one will be pretty cool
Yea I have a few... Actually most in the bkg are ready to fly ( 4*40 and my old favorite the Kougar which I flew w/ glow for a few years, and have it ready electrics) ... well except for the uncovered parts

Tips.... I'll definitely check out your thread, and I'm sure I'll be getting more tips than I'll be giving And yea, I'm finding the foam really fun to work with. I put it off for a long time for what ever reason; mainly I like working w/ balsa so much. But I have to admit, I really like seeing a plane come together so quickly. If this one works out, I hope to do a larger sport plane like yours.
I was going to hollow out the nose, but not sure if I will need the nose weight. Will wait and see. Not sure what you mean by lanes.... Sides maybe? If so sides, and bottom are 1" foam, and top is 2" w/ 2" triangles in the corners. Will carve the top rounded. I'll post a CAD detail tomorrow night. AUW: I'm shooting for 8 to 9 #s Since this is my first foam build/glass & paint finish I'm not sure exactly what to expect, but the uncarved/sanded fuse feels really light for it's size.

Anyway, what's the secrete to get email updates here? I have the option checked and I got a few the first day, but now nothing. I just happened to look at the thread before heading to bed and saw all the new posts.
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Old 12-05-2006, 03:45 PM
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rcav8r,

Opps I ment to say "planes" dimensions. LOL!. Mine was right around 8 1/2 punds. Did you post what your setup will be I assume you are running two motors. Any ideas on what you plan to use? That is some thick foam you are using, I can't tell if you have a foam cutter in the back or not but that pink foam is rally strong and you could easily go to 1/2 or even 1/4 inch and it would be plenty strong and may save you some weight. Even at 1 inch though she should float pretty good. Great job again my friend, looking forward t watching you build man!

Tips

Tips.... I'll definitely check out your thread, and I'm sure I'll be getting more tips than I'll be giving And yea, I'm finding the foam really fun to work with. I put it off for a long time for what ever reason; mainly I like working w/ balsa so much. But I have to admit, I really like seeing a plane come together so quickly. If this one works out, I hope to do a larger sport plane like yours.
I was going to hollow out the nose, but not sure if I will need the nose weight. Will wait and see. Not sure what you mean by lanes.... Sides maybe? If so sides, and bottom are 1" foam, and top is 2" w/ 2" triangles in the corners. Will carve the top rounded. I'll post a CAD detail tomorrow night. AUW: I'm shooting for 8 to 9 #s Since this is my first foam build/glass & paint finish I'm not sure exactly what to expect, but the uncarved/sanded fuse feels really light for it's size.

Anyway, what's the secrete to get email updates here? I have the option checked and I got a few the first day, but now nothing. I just happened to look at the thread before heading to bed and saw all the new posts.[/quote]
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Old 12-05-2006, 06:13 PM
  #24  
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[
I really hope to have it done for the Cedar Creek Electric fun fly. Not sure if it will take off on the grass as the 3" wheels ( exact scale BTW ) sit at the bottom of the fuse for a whopping 1.5" of clearance. Did you hear Keith got permission to make it a multi day event? Will probably do a shameless plug here once I get more info. I'll be helping out Keith this year. Too bad it rained for the one this past summer. The others were a blast.

Dave:

Yes this yr will be a 2 day event and also will have overnite camping, besides if enough interest we can have nite flying. Am evpecting a great turnout this coming yr.

...Keith...
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Old 12-05-2006, 06:18 PM
  #25  
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My email updates seem to work "some" of the time. Missed a few posts, but finally got an email notification.

Doug
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