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The Winter Cardinal crawl... err... build is underway.

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The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Thu Sep 21, 2017 10:14 pm

I started my Brodak Cardinal kit. I decided to build the fuselage first, and stiffen the tail from flexing in the lateral direction(waggling back and forth). I took a long CF flat-bar 7/16" x 1/16" and embedded it. I haven't epoxied it yet... I wonder if thin CA would grip the CF bar better. It sure would be easier. It's recessed by 1/32" on each side. And I'll taper the whole aft section of the fuse. This re-enforcement should allow me to taper it more than if it weren't stiffened without reducing its effectiveness.

First I cut the slot along my center line using an aluminum angle iron as my guide. Check out my long narrow fuselage glass. Pretty cool, huh.


Then I widened it to snugly accommodate the 1/16" flat-bar. That long angle iron is a 16th" with 220 grit paper on one face, so that was convenient. I just had to take care and not accidentally split the whole front end in two... I didn't, Lol.


And finally, I embedded the CF bar into it. It shouldn't flex sideways... I hope. I have heard that Cardinals are notorious for twisting and wagging their tails. The flat-bar weighs 1/2 ounce.


Next, I have to decide the lightest and strongest way to stiffen it against torsional twisting. I've been considering laminating 64th" ply, or carbon veil, or light fiberglass. Whichever I choose to use, other than veil, will have silkspan doped over it too.

My question to any best-guessers out there is: for the sake of stiffness against torsional flexing, and considering the weight penalty, would it be better to apply veil(if I so choose) with epoxy or dope?

We'll  talk about it on our video hangout tomorrow night.
For those that don't know, we are just now starting to do a group build, comparing ideas and notes. Some of us broadcast from our shop. I cannot host it from my shop due to my lacking computer needs out there. But join us if you're interested. The video Hangout reruns are on the "Stunt Hangar" Youtube channel too. All the ones I host are on my own channel home page as well.

The whole rest of the kit is still in the box.
Rusty

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Re: The Winter Cardinal crawl... err... build is underway.

Post  Cribbs74 on Thu Sep 21, 2017 11:16 pm

Considering doing the same thing with my newly built Twister.  You could always skin it with very thin contest balsa. Very little weight penalty. Holding it in place with a thin coat of epoxy. If skinned it would never break free.

As to the torsional rigidity, do you really think that is required? Windy more than likely never did anything to that effect.

Ron


Last edited by Cribbs74 on Fri Sep 22, 2017 2:11 pm; edited 1 time in total
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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Thu Sep 21, 2017 11:38 pm

Cribbs74 wrote:Considering doing the same thing with my newly built Twister.  You could always skin it with very thin contest balsa. Very little weight penalty. Holding it in place a thin coat of epoxy would hold it in place. If skinned it would never break free.

As to the torsional rigidity, do you really think that is required? Windy more than likely never did anything to that effect.

Ron
Though I didn't list balsa, I did think of it. Can you buy 64th"... you can certainly sand 32nd" down though. Much cheaper than thin ply, and you can run the grain any way you like. Thanks for reminding me.

Did Windy ever build a profile Cardinal? I was thinking not, but point taken anyway. You know how I like to try things just for the heck of it.

I never realized how much torsional rigidity mattered till I watched one of Wayne's profiles fly recently. I had coincidentally eyeballed his wing/stab alignment on the ground and it was perfect. Then it flies by later on and Mike says, Dang, look at that crooked stab! I couldn't believe my eyes, it was twisted something awful. Back on the ground, it was again straight and parallel as an arrow. So, yes, given the reputation of the Cardinal, I think it is worth the trouble. Not that it'll ever happen, but I am trying to learn to build a perfect profile stunt ship.

Obsessive Rusty... but not quite as obsessively and experimentally meticulous as RRRRno names, Lol

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Re: The Winter Cardinal crawl... err... build is underway.

Post  Cribbs74 on Fri Sep 22, 2017 2:13 pm

Yeah, don't know if he ever did a profile. Mostly you find flexible tail sections are due to overzealous sanding.

I know mine is because of that Very Happy
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Re: The Winter Cardinal crawl... err... build is underway.

Post  Ken Cook on Fri Sep 22, 2017 4:09 pm

Rusty, I use the strip method all the time just as you show. I would go directly to Bob Hunt for your veil questions. Either e-mail him or go to the vendors section under Robin View Productions and get his phone number. Bob uses it exclusively and has been doing so since it's introduction. I personally just dope it on. If Bob shows up this weekend at the New Jersey Circle Burners field. I will ask him as well. Vintage Combat is this weekend and Bob has participated in it.
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Re: The Winter Cardinal crawl... err... build is underway.

Post  fredvon4 on Sat Sep 23, 2017 11:49 am

I have done this a few different ways

First was a Pat Johnston Ring Master and I sort of copied Mike Pratt's Primary Force kit method

I am pretty sure for competition PROFILE---- max fuselage width- aft of flaps is 3/4".

All I am noting here is the focus should be weight and strength....if final width is a couple 16ths wider than the 1/2" base so what

My goal on the Ring Master was stiffer for same weight....came pretty close

As is common these days I cut in new longer Maple motor mounts = total weight gain....I sort of reduced a bit with a few lightening holes well aft of the engine mount area

Noted: a profile fuselage only bends two ways.... left and right bending aft of TE, and twisting aft of TE

Engine crutch, nose and wing areas are usually very darned stiff

One sure way to reduce the twist is ZERO rudder offset.
Another is Stab perfectly aligned so hing line is not skewed. With this true, then each Elevator half must not have any difference

Noted: at 50+ MPH there is a lot of forces pushing on the control surfaces... a skewed hing line or unequal elevator half section will twist the fuselage relative to the wing

Rusty has one of the better ideas for reducing BEND.....

I prefer a NON rounded Fuselage profile, so I add a long strip of 1/64th ply to the top and bottom of the fuselage....this, coupled with the center located CF strip, will add to resisting BOTH bend and twist

CF veil, Lite FG, or silkspan... IMO.....do nothing but add weight....BUT they do promote a better seal/substrate for final paint
Resisting twist by Laminating 1/64th ply or 1/32 Balsa on both sides adds weight but is very effective....

What you end up with is a PLY cross section with 1/2 Balsa center, two epoxy layers, and two outer layers of dissimilar grain material ...adding CF inside this adds nothing but weight... This new Ply build up adds a lot of resistance to both bend and twist
This new width fuselage build up can be radically sanded back thinner

For example; one stunt hanger member took a 1/2" fuse ....cut out a lot of the 1/2 fuse balsa and laminated a 1/8th Hard balsa sheet to each side. Then sanded it all back a lot with his preferred rounded top and bottom profile...

He did before and after bend and twist and weight comparisons that show the result was near same weight but a LOT stiffer

In this case, weight of glue was controlled by hair spray (lacquer in a can) seal of the balsa sheets before rolling on and then toilet paper removing the (finish resin) epoxy...wing skin sheeting preferred method...the hair spray limits the amount of heavy Epoxy that can absorb into the open pore balsa

To further control weight you can cut a LOT out of the inner balsa fuselage..Mike Pratt's method adds 1/2" foam to fill the voids

An other consideration is to research the model to see if it typically needs weight in the aft or nose for the intended engine...as MOST stiffening methods do add weight aft of the TE




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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Sat Sep 23, 2017 5:30 pm

Okay, thanks for the ideas on preventing twisting.
Before we move ahead on that I'll sand and shape the fuselage with some taper and rounding the edges. I would like to be way past this step, but attending to my injured bride has put a cramp into my speedy style. I'm gonna hit the shop after the Carolina game and see if I can get on a 3 hour roll. I'm disappointed to miss 1/2A Day today, but I may try to get the PT-19 flyable tonight too. Should be doable.
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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Tue Oct 10, 2017 11:40 am

Over a couple of sessions lately, here's where she is.

Made the tail wheel block. It's glued together, but I still have to make the bends for the axle before mounting it into the fuselage.


Made a wing root plug for aligning the doublers. It'll help keep them from sliding while gluing and clamping.



And now the beams are glued in place.

If you noticed in earlier fuselage pics, there was a notch cut out to receive the hardwood LG support. But since I'm going to mount the gear in the wing, I plugged it with balsa instead. I saw no reason for the hard wood since it's heavier, and also I figured it was a worse stress riser than similar wood to fill the gap.

And now, I'm off to the shop to check the glue job and apply the doublers.
Rusty

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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Tue Oct 10, 2017 1:20 pm

Glued the OB doubler in place. I carded the epoxy off till it was just shiny on both surfaces. I hope I used enough. And when I stood back to admire it, I realized I had forgotten to put the fiberglass layer in between. DOH! I may add a tripler like the Twister, but probably not. And I won't forget the glass on the inboard side. One under the doubler and one under the tripler.

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Re: The Winter Cardinal crawl... err... build is underway.

Post  fredvon4 on Tue Oct 10, 2017 1:47 pm

While admittedly it is negligible weight, the FG cloth between two plys does not do as much as it can IMO...

I tend to think where FG cloth makes sense is on the outside because it adds a lot of strength AND provides a good (once leveled or filled) smooth finish base

I have done it both ways... looks like your Cardinal nose is gonna be plenty stout so i would not sweat it
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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Tue Oct 10, 2017 3:50 pm

fredvon4 wrote:
I have done it both ways... looks like your Cardinal nose is gonna be plenty stout so i would not sweat it
Thanks, Fred. Yeah, I'm not too worried about it. I have never glassed one before, but you know how I just like to do something new on every one I build. I'm glad to be getting a little bit done here and there. And I need to take a break from the Cardinal soon and get that Twister's leaky issue fixed in the next day or two.
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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Fri Oct 13, 2017 11:56 pm






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Re: The Winter Cardinal crawl... err... build is underway.

Post  Cribbs74 on Sat Oct 14, 2017 8:47 am

Top notch work Rusty. Moving quick on this one!
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Re: The Winter Cardinal crawl... err... build is underway.

Post  getback on Sat Oct 14, 2017 8:50 am

Looking stout there Rusty , i really like the idea of using those old irons for weight that just looks cool to me , got one of those here somewhere if i can conjure it up i will use it . I Love This Forum!
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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Sat Oct 14, 2017 10:09 am

It's hard to see in the doubler gluing, but there's an iron flat bar I can hardly pick up off the table I'm using too. My son gave it to me as a portable anvil. I love those irons, they came from my MIL's house and date way back to their farm livin.'

Ron, I'm surprising myself. I'm not sitting around thinking about it so much as just doing it. I've finally built enough models to just know what I'm doing without second-guessing. And, I'm actually doing better quality work. A little bit most days. Otoh, I just tried dry flying an OH8 in the den and almost collapsed, so I don't know how that little part of the hobby is looking with 6 days till Stuntersville. But it'll be what it'll be.
Rusty

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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Sat Oct 14, 2017 7:12 pm

I came in while waiting for old Permatex to soften in acetone so I can clean it and replace the NVA on the Twister's FP.40. I started reading Fred and Ken discussing Brodak P-40 ARFs and started writing until I decided it was irrelevant to the thread's content, so I cut and pasted it here. Just my thoughts on building either a kit or plans or a self-designed scratch job. Comparing that with the chore of sticking together an ARF.

I gotta admit, compared to putting my P-40 together, my current Cardinal kit building project is bringing me a great deal of fun and anticipation. I could say it's good for my head. I think and do, and mildly engineer, and put my personal touch on every part of it. I drift off to sleep figuring how the next steps will be worked out, and I dream of flying it, even at this early stage. I've got some of my old excitement back. I needed that since I've been rather oppressed by semi-crippling arthritis for a whole Summer and now the Fall.

It's actually moving along pretty quickly for me. I even expect to be doping and painting the completed fuselage within a couple of weeks after Huntersville. I like my new approach of building the fuselage first. Building seems to be good for the soul, where assembling an ARF is more of a chore. Every day this week, I've gone out to the shop to fix the Twister's engine fuel leak, but have been drawn straight to the building table and back burnering the Twister. Even though I have to finish fixing it before tomorrow, I still sat down at the table first and sanded some.

Participating in the Video hangout group-build is helping me keep my head in it too. That's fun and I get some good ideas from the other guys, and I hope I'm passing some good ideas along back to them too. The past couple of shows have had enough building going on that I can zoom in on someone who is dilligently projeckin' so the YouTubers(and re-run watchers) can watch that while the rest of us jabber on about other ever-changing topics.

Okay, break time is over, back out to re-assemble the Tazz machine for a Sunday at the field.
Later,
Rusty

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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Sat Oct 14, 2017 7:15 pm

getback wrote:Looking stout there Rusty , i really like the idea of using those old irons for weight that just looks cool to me , got one of those here somewhere if i can conjure it up i will use it . I Love This Forum!
Eric, if you can conjure one, how's about conjure me up a couple too. You must have some powerful MoJo to turn space into 10 pounds of black iron Lol.

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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Sun Dec 03, 2017 3:33 pm

Well, the last post was 5 days before I dropped out of my Winter build, but I got out to the shop today and fooled around a bit. I wanted to make sure the Cardinal fuse is still straight, which it is. I finished some of the shape sanding I had started and pinned the rudder & vertical stab in place. I notched out the air scoop under the engine, so now I can leave it looking a little more like a Cardinal while I'm on temporary leave. I figured I better lay off the sanding since the last thing I need right now is a case of balsa lung.

I have a color scheme now. Mirror bright Chrome Monokote base color on the wing with Coibalt blue Flite Streakish accents. Something similar in Lacquer on the fuselage. A diversion from my usual colors, which I'm tired of. I plan to paint it before building the wing.

So here's a picture of the RedBird(or Bluebird) while it waits on me to get back to work on it.  Sorry if its too big for low band, I'll shrink it when I can get from the tablet to the computer.


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Re: The Winter Cardinal crawl... err... build is underway.

Post  roddie on Sun Dec 03, 2017 3:52 pm

"Balsa-Lung".. Laughing That got me laughing Rus! Kudos to you.. for finding the strength/desire under the circumstances; to pay attention to your builds-in-progress! (I'm actually not surprised one bit..) You were one of my first influences here on the forum Rusty.. and you continue to inspire me!
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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Sun Dec 03, 2017 4:02 pm

Thanks, Rod. My head is still in it, just not all the stuff beneath my head.

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Re: The Winter Cardinal crawl... err... build is underway.

Post  roddie on Sun Dec 03, 2017 5:21 pm

RknRusty wrote:Thanks, Rod. My head is still in it, just not all the stuff beneath my head.

Yes.. but...... what's in your head, has a LOT to do with the rest of your body.. and a positive mind-set can have a profound effect on physical healing.

I enjoyed the StuntHanger vid-segments on how you stiffened-up the fuse. Cool stuff.. and worth the extra-effort for a better flying airplane!
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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Thu Mar 01, 2018 10:19 pm

I'm easing back into some shop action. Now that it's not so cold and wet I'm getting little bits done every few days. I took some pictures before I wrapped up tonight's session.


This is as far as I’ve gotten. Engine mounted with blind nuts, plywood nose ring installed(1/2” backing ring can be added later), inboard tripler ready to be glued on and then sanded to shape.





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 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.

That's all for tonight.
Rustyt

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Re: The Winter Cardinal crawl... err... build is underway.

Post  Mark Boesen on Thu Mar 01, 2018 11:08 pm

Looking good Rusty, great airplane!

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Re: The Winter Cardinal crawl... err... build is underway.

Post  RknRusty on Fri Mar 02, 2018 12:23 pm

Hi, Mark.
That's a nice one. Is it yours? I like the old time style cockpit. Ive been wondering how to shape it, and am so far stumped. Also the silver color, as I'm planning chrome and cobalt blue. For once I'm looking forward to painting it. I want to work at finishing the fuselage gluing and sanding this weekend.

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Re: The Winter Cardinal crawl... err... build is underway.

Post  Mark Boesen on Fri Mar 02, 2018 2:42 pm

It was the last plane i built...the Magnum is still not finished.
Love the Cardinal, but never was a big fan of the modernistic canopy, was gonna put one the kids plastic toy heads in cockpit and never did, also it does have a little flex in the rear fuselage. Took 3rd in Intermediate at the Nats with it, still hangs in basement waiting to fly again.  LA .46 3-4 gaskets, med venturi. cut down Top flite 'Power prop' 11x4 to 10.5x4, nice 2-4-2 break. Sig dope, with polyspan, always liked yellow wings.
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