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Author Topic: My Winter build - Brodak Cardinal  (Read 3572 times)

Offline RknRusty

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My Winter build - Brodak Cardinal
« on: October 11, 2017, 12:01:52 AM »
I like to have a new ship every spring, and it takes me a long time to build one. I've posted a few pictures, questions and ideas in our "What did you do in your shop" thread, but at my pace those will be too spread out to be good for a build thread with Q&A as I go. I post all of my builds in excessive detail as "RknRusty" on my other favorite forum(see link at the bottom of my sig). But for Stunthangar, I'll keep it simple and just show my work and ask questions.

I am also featuring it in a group Winter Build segment of the Stunthangar Video Hangout on Monday and Friday nights. Reruns are there too. A bunch of us are concurrently building models and discussing and comparing our methods of madness and genius.

So to kick it off, here's the fuselage coming together. The first few steps shown here are in the ..."in your shop" thread with  more detailed descriptions. And the last couple are new as of Sunday and today. I'll keep it here from now on.

First step was to stiffen it against lateral tail-wagging with a long 1/16" x 7/16" CF flatbar.

I'd planned on skinning it with something to prevent torsional twist, but the flatbar seems to have stiffened it in that direction too. And that alone cost an ounce, and I think it'll fly just fine without me getting carried away with extra reinforcement all over the place. I'm open to contradictory opinions, I am here to learn.

Next I made a wing root plug to help align the doublers and hold them in place while the epoxy hardens.


Glued the engine beams last night. I also glued a piece of balsa to plug the slot where the LG were to bolt. I used balsa instead of the supplied hardwood block because the gear will be wing-mounted. And I figured the balsa would cause less of a stress riser... and, of course, be lighter.


And the outboard doubler went on today. I painted each surface with epoxy and squeegeed it all off with a card until they were just shiny. Gawd, I hope I used enough glue. It did look good later in the day after hardening under heavy weight. My shop is over 80 degrees, so my 30 minute epoxy works pretty quickly. I usually give it 6 hours before inspecting and fiddling.

After standing back to admire my work, I realized I'd forgotten to add a layer of 3/4 oz. glass between the fuse and doubler. DOH!. I usually don't, but I wanted to this time. I'll still do it on the inboard side. It gets a tripler too. My Twister in fact has triplers on both sides, so I might do that on this plane. I can use a sheet of glass under there if y'all don't think I'm just spending weight for no good reason.

Now is where my first questions will come regarding the nose ring and engine placement. I'm not 100% sure after rereading the instructions and staring at the plans, so stand by for that tomorrow if I'm still not sure. One last detail I did today is made the tail wheel gear, all except for the bends for the axle. I'll epoxy it on with a wrap of glass or veil around it.


Hey, how do y'all like my cool portable fuselage building glass... It was a 48"x 8" window shelf in my MIL's kitchen window before she moved away and we family dutifully raided collected items we saw as valuable. The whole 4x8 table has a large 3/8" glass under the sheet-rock surface too.

Good night for now,
Rusty
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

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Offline James Holford

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Re: My Winter build - Brodak Cardinal
« Reply #1 on: October 11, 2017, 02:26:05 PM »
Enjoyed the read Rusto

Sent from my SAMSUNG-SM-G891A using Tapatalk

Jamie Holford
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Offline Randy Cuberly

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Re: My Winter build - Brodak Cardinal
« Reply #2 on: October 11, 2017, 03:46:09 PM »
Don't know if this will help much but here's a picture of one I built from the kit many years ago,  It doesn't, unfortunately show many details of the nose ring but it is shown there.

It's actually just a plywood ring with a balsa block behind it joined to the fuselage and the fuselage doubler.
I mounted the engine with a clamp to get the location of the spacing for the plywood ring with the balsa ring behind it.   Then I took the back plate for the spinner I intended to use and spot glued (medium CA and kicker for this) three small pieces of 1/32 plywood to the back of that.  I then spot glued the plywood ring to the back of the spinner back plate (to the small pieces of plywood of course) with the oversize balsa ring glued to the back of the plywood ring. Then mounted the spinner on the engine with a prop hub (cut from an old wooden prop), then put the engine in place on the fuselage with the balsa ring against the front edge of the fuselage and glued it there with the engine clamped in place.  Then I marked the engine mounting holes removed the engine drilled the mounting holes put the blind nuts I place then reassembled the whole mess again.  At this time you can then shape the oversize balsa ring to blend with the spinner and plywood ring and the fuselage.  You can also put the balsa doubler on the fuselage and shape it also to the spinner and fuselage.

Then take the whole mess apart again and remove the spinner back plate from the plywood nose ring (a long xacto carving blade works well fro this), then finish the fuselage to mount to the wing!

It's actually a lot more complicated to describe than to actually do.  It's just logical!

Randy Cuberly
PS:  The airplane was passed around a lot and trained a couple of fliers to Advanced and one mostly to Expert.  It was an excellent flier with the LA46.

Randy Cuberly
Tucson, AZ

Offline Dave Harmon

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Re: My Winter build - Brodak Cardinal
« Reply #3 on: October 11, 2017, 08:24:32 PM »
Rusty.....

It's a lot easier to bend the tailwheel wire before you epoxy the assy onto the fuse.
Fortunately....I remembered to do this on my Oriental!!

Oh....check that the incidence for the wing is at zero with the stab slot and inside of the engine rail.
The Oriental was waaaay off and that cost a lot more time to get it all adjusted and fit right.

Randy is correct about the spinner ring....I did the same thing with some blocks and it worked out fine.

Dave

Offline RknRusty

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Re: My Winter build - Brodak Cardinal
« Reply #4 on: October 11, 2017, 08:48:36 PM »
Thanks, Randy, now I've got the idea. I had no problem picturing what you were saying. Big help, so now I can move forward with it.

Hey, Jamie, thanks for reading my docu-story. Seems like every time I start typing, no matter how hard I try, a story emerges rather than a documentary.
Rusty

Rusty.....

It's a lot easier to bend the tailwheel wire before you epoxy the assy onto the fuse.
Fortunately....I remembered to do this on my Oriental!!

Oh....check that the incidence for the wing is at zero with the stab slot and inside of the engine rail.
The Oriental was waaaay off and that cost a lot more time to get it all adjusted and fit right.

Randy is correct about the spinner ring....I did the same thing with some blocks and it worked out fine.

Dave
Hi Dave, I really appreciate the tips. In fact, one day last month I copied and saved a good list of tips you posted to me, and I'm keeping them in my Cardinal file to check as I go.  Before I glue the doubler on the inboard side, I'll mark all of my reference lines... Or as Windy would say, My "datum lines."
And yeah, I haven't glued the TW block in yet. I marked it to bend and put it away till I finished second guessing it too. That's why I'm a slow builder, I think too much.

What about 3/4 glass between the doubler & tripler on the nose... any real benefit? With LA power, vibration is not an issue, just strength. And again, weight.

You guys are great.

Randy and Dave, It would be great if y'all would like to join James, me, and the rest in our live hangouts on a Friday or Monday evening to talk about building, flying and general bullshit.
Rusty
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

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Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
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Offline RknRusty

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Re: My Winter build - Brodak Cardinal
« Reply #5 on: March 03, 2018, 11:08:45 PM »
I'm back in action!
Mercy, just about a week after my previous post, the evening before the October contest in Huntersville, I was excitedly loading up the aircraft carrier to make the Friday morning trip. I'd been limping on that hip for 6 or 8 weeks when suddenly in my workshop, KAPOWWWWCH! It went from mere aching to hurting with screaming crippling pain. I didn't know then but the damn thing was broken, 3 fractures in the femur just under the ball. And misdiagnosed as spasms for 3 more miserable weeks, housebound and barely able to move around with a walker. So much for the contest and the Cardinal build. Finally surgery to pin and clamp it on December 5th. Now I'm healing nicely and finally able to get to the shop and carefully move around a fair amount without the cane. Whew, I was going bat-ass crazy cooped up all that time.

So I'm finally easing back into some shop action, and Will Davis even coaxed me onto a swiveling bar stool to fly a plane at the meeting last Saturday. He spun the chair while I flew the plane. Even did a tenuous loop or two.

Now that it's not so cold, windy, and wet I'm getting little bits done in the shop every few days. I took some pictures before I wrapped up Thursday's session.


Below, these pictures are as far as I’d gotten as of Thursday, and I worked some more on shaping the nose today. Engine mounted with blind nuts, plywood nose ring installed(1/2” backing ring will be added later), and the inboard tripler ready to be glued on and then sanded to shape. I hope to get that finished Sunday.

Today I glued the nose ring in place, did some more shaping, and removed the excess balsa on top. So It's starting to look pretty good now. I'm getting stioked, and it feels great to be getting my head back in the game. Excitedly looking forward to H'ville and Triple Tree(the Joe Nall stunt contest).





That’s an FP.40 for the mockup, but it will probably be an LA.46 with the same footprint when it’s finished. I have a couple of old ones that I hope will combine to be a good working engine.

I need to get some new sheetrock for the table top before I build the wing. I’ll paint the fuselage before installing the wing. This is all backwards from my usual building order.

Boy, my mental health has taken an instant turn for the best since I can get out of the house and do some shop work. I'm so glad Will got me to fly in the chair. I was a happy boy after that therapeutic flight.

That's all for tonight.
Rusty
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
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Offline Steve Helmick

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Re: My Winter build - Brodak Cardinal
« Reply #6 on: March 04, 2018, 11:13:45 AM »
Unfortunately, I'll have to predict major flexing and cracking at the wing TE, because you've created a stress concentration even worse than normal. I would have strongly discouraged putting the flat CF spine in right there. If you'd moved it upwards an inch or so to allow overlapping the wing TE by 3" or more, it would have been much better, IMO.   :'(

At this point, I'd suggest putting a 1/32" ply doubler from the stock nose doublers back about 3" aft of the TE.   y1 Steve
 
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Offline Bootlegger

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Re: My Winter build - Brodak Cardinal
« Reply #7 on: March 04, 2018, 11:33:02 AM »

  Randy C, as an L S U fan I sure do like the colors that you chose, Purple & Gold are the colors of the L S U Fighting Tigers, and this is baseball season, my favorite college sport...   Geaux Tigers    y1 #^
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Offline RknRusty

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Re: My Winter build - Brodak Cardinal
« Reply #8 on: March 04, 2018, 01:17:25 PM »
Unfortunately, I'll have to predict major flexing and cracking at the wing TE, because you've created a stress concentration even worse than normal. I would have strongly discouraged putting the flat CF spine in right there. If you'd moved it upwards an inch or so to allow overlapping the wing TE by 3" or more, it would have been much better, IMO.   :'(

At this point, I'd suggest putting a 1/32" ply doubler from the stock nose doublers back about 3" aft of the TE.   y1 Steve
Ouch.
I have a sheet of 1/32" so I can make a pair of doublers that extend up to and meet the front doublers. The front ones are 1/16" in this kit.

Good catch, Steve, that was a pretty bad oversight on my part. Thanks,
Rusty
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
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Offline RknRusty

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Re: My Winter build - Brodak Cardinal
« Reply #9 on: March 06, 2018, 12:20:03 PM »
Correction, I have a sheet of 1/64th ply. I think that and epoxy should hold it together. Hopefully it'll blend in without making it look too funny.
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
www.coxengineforum.com

Offline Chris Fretz

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Re: My Winter build - Brodak Cardinal
« Reply #10 on: March 06, 2018, 01:16:23 PM »
There just doesn't seem to be a great way to stiffen up the fuse... I'm wondering what to do with my Cardinal.
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Offline peabody

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Re: My Winter build - Brodak Cardinal
« Reply #11 on: March 06, 2018, 02:42:58 PM »
Winfred's first Cardinal had a "shaped" fuselage that had doublers to the approx. balance point.
He covered the works with heavy silkspan....and LOTS of dope and sanding.

Very little flex in the tail

Won several local contests at the Expert level

Offline RknRusty

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Re: My Winter build - Brodak Cardinal
« Reply #12 on: March 06, 2018, 08:49:01 PM »
There just doesn't seem to be a great way to stiffen up the fuse... I'm wondering what to do with my Cardinal.
I think my method is worth trying. It'll cost about an ounce and small change after I add the 64th ply doublers. My rickety old Cardinal ARF flew pretty well without any special mods. It won a couple of trophies too. I always try something I've never done before on every model I build, just to see how it works.
Rusty
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

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Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
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Offline GERALD WIMMER

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Re: My Winter build - Brodak Cardinal
« Reply #13 on: March 06, 2018, 09:33:03 PM »
Hi Rusty
Your 1/64 ply reinforcers should spread out the stress around the TE nicely in my view .
My old P51 profile with the Hawk 60 developed a wobbly tail with lots of little cracks that were sorted out when I planted it and the tail came off , after re-gluing the area it was much more rigid and flying normally again!
I just can't stop experimenting with my model builds and find it hard to build per plan or straight out of the box without some customizing, its just part of the fun.
Regards Gerald

Offline Steve Helmick

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Re: My Winter build - Brodak Cardinal
« Reply #14 on: March 06, 2018, 11:02:44 PM »
Correction, I have a sheet of 1/64th ply. I think that and epoxy should hold it together. Hopefully it'll blend in without making it look too funny.

I was re-reading this to see if there were any better suggestions, and was thinking the 1/32" ply might be too thin. Then I got to thinking that two or three layers of 1/64" would be better, as you could then taper the aft edge easily. I think the CF strip will be brutally stiff, and you may even have trouble keeping the CF bonded between the top & bottom halves of the fuselage slab. I didn't see what the dimensions are for the CF strip, however. If your rules call for a 1/2" thick fuselage, well....

I am very interested in how this turns out, but I wouldn't do any of this. Always, always, always, put the strong stuff on the outside of the surface you're building, be it profile fuselage, wing or horizontal tail. ALWAYS. A layer of 1/64" ply on both sides of a provile (sic) is amazing, easy, and fairly cheap. I don't believe it would need to be full fuselage depth...2" wide should do quite a lot. 

If you want to use CF, skip straight to .5 oz and use epoxy, and consider two layers up toward the wing TE and around the stabilizer joint. I don't subscribe to the view that CF veil is only good for hardening the surface...rather that a heavier grade...and epoxy...need to be used. The epoxy does a much better job of bonding and also a much better job of isolating the fibers, preventing them from cutting each other when under stress. If you do some research on fiberglass cloth vs. mat, they say that cloth is not as strong as mat, because it will "zipper" along the weave, while mat won't, because all the fibers are random and all are working all the time. Well, that's what they say.  y1 Steve
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline RknRusty

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Re: My Winter build - Brodak Cardinal
« Reply #15 on: March 07, 2018, 05:27:15 AM »
Steve, I appreciate your thinking it over. I could laminate the ply to make it a 32nd thick. The CF flat bar is 1/16" x 7/16" so I have a 32nd groove on each side of the fuse. I had planned to use light Spackle to fill that gap and silkspan on the whole fuse. I also have veil and 3/4 oz. fiberglass, but I don't want it to be a lead sled. I'll report back with whatever I decide to do.
Rusty
DON'T PANIC!
Rusty Knowlton
... and never Ever think about how good you are at something...
while you're doing it!

Jackson Flyers Association (a.k.a. The Wildcat Rangers(C/L))- Fort Jackson, SC
Metrolina Control Line Society (MCLS) - Huntersville, NC - The Carolina Gang
Congaree Flyers - Gaston, SC -  http://www.congareeflyer.com
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Offline TDM

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Re: My Winter build - Brodak Cardinal
« Reply #16 on: March 07, 2018, 06:16:02 AM »
Rusty that 1/16 Cf in the fuselage will only add weight to the tail.  Your chief worry in fuselage flex it torsional rigidity and that is addressed with carbon bias at +-45 degrees. for rigidity in the other direction flat thin carbon added to the outside of the wood will do just fine.
Easy composites has 100g/M2 unidirectional carbon that comes in strips with some kind of binder in the fibers. You can cut strips out of it with a straight edge and a exacto blade place them in position and you are good to go.
The best material you can use on the fuse is not that stuff. Carboweave C60 is a spread tow material that has 3 layers of material in it two are +-45 and one at 0 degrees which makes it ideal, for the reasons I mentioned above, to stiffen your fuselage for the least weight penalty.

Carbon is a great asset but it has to be used wisely other wise it goes on for the ride.

One more thing if you sharpen t he top and bot om of the fuselage say 45 degrees and blend in the sharp corner it will take some weight off the tail and the cureve will give some more strength, win win situation.
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Offline Jim Mynes

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Re: My Winter build - Brodak Cardinal
« Reply #17 on: March 07, 2018, 06:43:05 AM »
Steve, I appreciate your thinking it over. I could laminate the ply to make it a 32nd thick. The CF flat bar is 1/16" x 7/16" so I have a 32nd groove on each side of the fuse. I had planned to use light Spackle to fill that gap and silkspan on the whole fuse. I also have veil and 3/4 oz. fiberglass, but I don't want it to be a lead sled. I'll report back with whatever I decide to do.
Rusty

I wouldn’t fill the groove with spackle. It will add zero strength or stiffness, and may crack if there is any flexing.
I would create a bunch of balsa dust by sanding the fuselage down flush to the CF strip, and extending that thinness forward of the wing TE about 1.5 inches. Then laminate 1/32 balsa to both sides to restore original dimensions using the squeegied epoxy method. I think you’ll find the laminated balsa to be much stiffer than a half inch plank.
You could even remove some of the plank prior to laminating over it. The stiffness will come from the skin, and much of the plank is just filler.
Another idea I had, probably more messy, would be to squeegee some epoxy/microballoons onto the rear of the fuselage, allowing it to fill your 1/32 groove and wet the rest, and lay your carbon veil on. Saturate and squeegee. You could even extend this up to the nose ring if you want to make up for your missing glass cloth.
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Offline Skip Chernoff

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Re: My Winter build - Brodak Cardinal
« Reply #18 on: March 07, 2018, 07:14:53 AM »
Thanks for posting your Cardinal build.We can all learn something....


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