Building Brodak Cardinal

Stuka Stunt Main Forum · 16 of 16 known posts recovered

brian Hadley · Sep 20, 2001 08:43 PM

For those of you familiar with the Brodak Cardinal I have a question. I am just putting the wing tip blocks together and at least in my limited experience they seem like overkill in terms of weight. They consist of 1 1/2 in block and 4 3/16 in blocks laminated together. Of course they will get lighter with shaping, but after they are glued on there in no way to hollow them any further. Since I am at 6000 ft I want the plane to be as light as possible and I am wondering if I should redesign a lighter tip. Any suggestions?
Also, has anyone had difficulty in building this wing straight? I am having a heck of a time with this wing. Is this just my incompetance?
Are you out there Nils???
Thanks,
Brian

b · Sep 20, 2001 08:46 PM

#1 source

Sorry
That is (1) 1/2 in blaock and (4) 3/8 in blocks. Brian

Chuck Potts · Sep 20, 2001 09:01 PM

#2 source

For what its worth, I am also building the Brodak Cardinal at this time, and also had some questions about the same things! In fact, I e-mailed John at Brodaks web site, and he called me back on the phone. My first concern was that the wood used for the ribs was so light and soft, I called it "punk-wood". As I was handling the wing during construction, I kept breaking the ribs. I spent almost as much time gluing the installed ones back together as I did installing new ones. John insisted that when it is finished, it will be very strong, as well as light. And you know what? He was right! It finished out quite strong, but I have added some additional bracing in key places, namely around the center section ribs, as well as the bellcrank mount. As far as straight....you need to be sure to keep your wing pinned down securely on your work surface as you install the leading edge and trailing edge planking. When you finish out one side, turn it over and pin it down again before you finish out the rest of the planking. Planking it out "in the air" just won't work with this wing, as the wood is just too soft, and warps and twists too easily. It needs the board stiffness until all the planking is done.
As far as the wing-tips are concerned, just hollow out the inboard blocks, as you will probably need the weight in the outboard tip, anyway. Note: Both my blocks together weighed less than 1.2 oz., and I don't consider that too heavy.
Hollow out the lead-out area, and forget the rest. Chuck Potts

Steve Scott · Sep 20, 2001 10:09 PM

#3 source

One of several tricks is to compare the weight of similar wing components. Density of leading and trailing edge stock is often not equally matched. Just assemble with the heavier stock outboard. The lighter you can make the inboard panel, the less weight you need to add to the outboard.

Also, each stock may not be uniform for it's entire length. Measure a midpoint on a spar, LE or TE. If one end is heavier, I'd put that in the center. If you can't swap end for end, cut a new piece. Very doubtful that will be required on a Brodak kit.

Scott Riese · Sep 20, 2001 10:45 PM

#4 source

I'm on my THIRD Windy's Kit and yes the wing tips are overkill. HOWEVER, when you put those tip block on and mark them for shape and carve them YOU'LL have a lighter tips then buying new wood. My tips come out LESS then .5oz total both tips.
I like to make tips for the cardinal. Takes about ONE hour to do both tips if you have the right tools. You'll be pleased with the wood, and your work. SCOTT

Ty M. · Sep 21, 2001 02:23 AM

#5 source

Trust the wood and the plans. Those tips come out light and very nice. Just put the heavy wood on the outboard tip. I had no trouble building the wing, just do exactly like the instructions say to do. (" I don need no stinkin structions!!) I hope that is not your line

Mine came out, ready to fly less fuel at 40.1 oz. Even at 6,000 msl that will fly great, especially with the ST .46 I have on it. If you follow the plans and set the CG where is says, you will be slightly nose heavy, BUT you want it there for the first two or three flights. Move , add, or subtract weight as you get used to the handling and get it like you want. Tail heavy on first flight often leads to last flight. I covered mine with Poly span. That was a new experience. Patience. Take your time in doing the wing. The only thing I added to mine was span wise cross braces between the ribs for the first 5 bays. Left the tips open. This kept the wing stiffer for my taste. Ty

Steve Fitton · Sep 21, 2001 08:56 AM

#6 source

I built a Brodak Cardinal about a year ago. I found the wing to be a bit fragile during construction. The wood selection was good but the sizes used and the dimensions of the wing itself do make for a somewhat flimsy item during construction-you have to be a bit more careful than say, a brodak warbird wing which used the same wood sizes but is dimensionally smaller.
I took pains to fully hollow the inboard wingtip. It takes a little time to carve and shape the laminated tips. I would recommend taking your time and going slow so you get them right. My outboard tip I did not hollow (except to install the weight box) and the weight of the tip was sufficient that I only ran about 1/2 ounce of weight in the box.
I found the massive stab and elevator caused the tail to flex and "dance" in flight even though I did not taper the fuselage-there is alot of tail to apply twisting forces to the aft fuse. The plane flew allright though-just keep the finish light and be careful with the wing structure untill it is finished and thus"stable' for handling.
My technique for carving the tips was this: I placed the laminated block on the tip rib and traced the outline of the tip (with capstrip in place) I then worked on the tip off the airplane with exacto knife and sanding blocks, frequently placing it on the tip of the wing to make sure it still looked right. When the shape looked good and I had worked it down to the inked line of the rib I hollowed the block with the trusty dremel until I could see daylight lighting up the wood on the inside when I held the tip up to the sun. Then the leadout guides went in and the tip was glued onto the wing. I then finish sanded the edge of the tip block to match it to the capstrip on the tip rib and the job was done-but it was several hours of work for me, abd I found some of the sheets used in the lamination were harder than others and made carving a bit more difficult than when you use one solid block.

good luck, keep it light and use a strong motor!

Steve

Steve Fitton

DMoon · Sep 21, 2001 12:41 PM

#7 source

Lot's of good stuff here. I would suggest hollow out both tips. Never build weight into the airframe. You may not need it and then you won't be able to get it out. Build the plane as straight and as LIGHT as possible. If that means hollow out the outboard tip then you got to do it. If you leave the tip solid and then it is to heavy your wing will drop on every manuver. then you have to weight the inboard or cut into your outboard. Sand to shape. Tack glue them on sand to shape so the fit is exactly the way you want it. Then remove and get after it with the dremel tool. Have fun.

Doug

Doug Moon

LNeumann · Sep 21, 2001 02:31 PM

#8 source

I agree with Doug. I have had a couple of airplanes where I put a tip weight box in the outboard tip and then never added any weight to it because the tip was too heavy already. (Did I ever tell you about the pretty outboard tip I made for a Chipmunk out of Pine! You can't hollow pine enough I found out.) This goes especially for a profile because the engine and tank are on the outboard side of the fuselage already contributing to the tip weight.

If it is too light, you can put a little more weight in the weight box. If it is too heavy, you will be resorting to sticking chewing gum on the inboard tip.

Leonard Neumann

Leonard Neumann

Nils · Sep 21, 2001 10:43 PM

#9 source

LAST EDITED ON Sep-21-01 AT 10:57 PM (CDT)

I put .2 oz CF over all the wood in my Cardinal & it doesn't wag it's tail much at all for a profile. A little CF stiffens things up considerably. I HIGHLY recommend that you put some light fiberglass around the wing/fuse joint, at least to the high point of the wing. After I hit the post with mine I went all the way around the wing during the repair. I'm glad I did too, I had a stooge/deep grass problem a month ago & my engine kept running on the ground with a broken prop. It shook ALL the engine bolts out before a guy killed it for me. All that was holding the engine in (ST.46, PERFECT engine for this airplane, btw) was the fact that the nose ring wouldn't let it go anywhere. It ran for about 2-3 minutes in all. When I got all the grass cleaned out of it there was ZERO damage to the airplane other than a little scuffed paint that doesn't show. NO cracks anywhere. Btw, I used regular fiberglass finish resin to apply the glass, it works great & is a bunch cheaper than anything I've used. It's no heavier than epoxy either. You can buy it by the pint in any big variety store or auto supply. I bought a little kit that had some glass with it. I also recommend that you put some glass around the leading edge of the stab/fuse joint. I did have a tiny crack developing there before the stupid post jumped out & hit me. I glassed mine while I was rebuilding it with a chunk about the size of a silver dollar, no more crack, even after the loose engine fiasco. I still had to add a quarter ounce of lead in the tail, so the extra weight didn't matter. I use Evercoat Metalglaze (pn 100-416) to smooth it out & do my fillets. For a tail weight mount on profiles I drill a hole through the rear of the fuse under the stab big enough to accept a 4-40 blind nut, then I brush some epoxy in the hole to seal the wood & push in the nut on the outside of the fuse. Then I use one 4-40 bolt & flat washer through tip weights (half & or quarter ounce, mix & match) for tail weight. The lead under the stab is barely noticeable & easy to change until you get it right. With a dab of Loctite you don't have to reef the bolt down enough to smash the fuse. Snug will do. I'm afraid I disagree with Leonard & Doug on hollowing the outer tip. (edit-For this particular airplane!) I left mine solid & it still needs a half ounce of lead. Yours will need some too, I guarantee it. I see no reason to waste time removing MAYBE a half ounce of wood so you can turn around & replace it with lead. Doesn't make any sense to me. Oh yeah, the wing- I use a set of those Model Magic Magnet building fixtures that comes in that magnetic building board setup from Tower. The metal board that comes with it is all gridded & nice, but it's not big enough & you can't see any of the board anyway if you're building over plans. I went up to the steel place & told them I wanted a hunk of scrap heavy sheet steel at least 60" long & 20" wide & it had to be FLAT. I wound up with a piece over 60 X 24 for about $12. I screwed it to my building board (old interior door) with countersunk screws & shimmed it as needed to get it flat. That way I could build my wings with the whole works clamped down until I had to flip it over to sheet the bottom. Other than using the magnets I built it just like the book says & it came out fine. Btw, you can buy just the magnets & fixtures MUCH cheaper than the whole setup. If I had it to do over I'd go that route. The Cardinal has enough wing to carry a lot of weight as long as you have enough power. Mine weighed a hefty 56 ounces before repairs but the ST.46 pulled it with power to spare on 68.5' lines (center to center). I've broken 500 with it, so it flys pretty good, heavy or not. It flys the same as it did before repairs & I'm sure it put on an ounce or two after the fix job. One more thing, lose the wire gear! I used some gold anodized aluminum gear from Windy, works great! Also buy some real control horns & an rrowshaft pushrod. I use 3 ball joints & a double locked steel clevis on mine. 325 flights, no problems (except for the post). You will really like that airplane if you can get it built straight. From my personal experience I've found that straight is MUCH more important than light. Light & straight is the best, but straight is the most important, imo.
Nils

Scott Riese · Sep 21, 2001 11:22 PM

#10 source

NILES....You and LEO should get together and make an AIRPLANE. I'll rent the crain...LOL. I HOLLOW ALL blocks extra wood is JUST DEAD WEIGHT. This give you more room for finish.
SO you added a half oz of tip weight. THAT plane that you fly NEEDS 1.25 oz out there anyway!!!!! REMEMBER KISS. This isn't rocket science RIGHT MR.BUCK........OH BTW I got 4 hours into my next plane WING DONE, STAB an ELEVATOR ready to finish. KISS

Nils · Sep 22, 2001 02:21 AM

#11 source

Don't you try to KISS me you big oaf!

I am keeping it simple, you're the one wasting your time hollowing things so you can add more lead. Remember that fat-fu.., err, full-fused Cardinal you have that you had to put the 5 ounce brick in the middle of cuz it was TOO light?

Nils

PS-See ya in Salem in a couple weeks

Scott Riese · Sep 22, 2001 12:56 PM

#12 source

OUCH!!!!!!!Gee a full sized cardnial 50 oz ST-51 powered..OH BTW the weight is OUT out the PLANE. Took it out two years ago. I learned to FLY 23%cg ....AND your Cardnial 40 sized ship weight?
Scott (not so fat after all) Riese

Ty M. · Sep 24, 2001 01:55 PM

#13 source

Brian, after reading all the other comments, I must really agree on the one about using a carbon fiber push tube for the flaps and elevators. Call Tom Morris, he has some really good ones for dale. I used the wire in the kit, and it is flimsy, and when time permits, I will change out mine. The carbon fiber on the rear of the fuselage, from middle of wing aft. sounds good to me. That fuselage is light and does wag its tail, like a good bird, but bad plane.

VALLE · Sep 27, 2001 05:42 AM

#14 source

I´m on the way to bulid my second Profile Cardinal, Just finished the wood-work on the wing last week, I hollowed the inner tip but kept the outer solid. What you can do is to make the tip of three parts middle top and bottom, Pin them together with needles, hold the against the outer wing spar and draw the outline of the profile. Then disassemble and carve out the inner side. You can take away much more than you imagine.
I´m aiming on getting this model to weigh 1300grams. My first finished at 1320.

If anyone has good trimming skills, please help my friend JohnosGrym, by adding some thoughts on his RCO thread.

Valle
SWEDEN

captcurt · Sep 27, 2001 06:32 AM

#15 source

>
>If anyone has good trimming skills,
>please help my friend JohnosGrym,
>by adding some thoughts on
>his RCO thread.
>
>CU
>
>Valle
>SWEDEN

I sent a direct email to John recommending he come over to this forum for help. I offered some suggestions based upon my limited experience but thought he could get better, more precise Cardinal-related guidance here. Hopefully he re-posts all of the preceeding info here.

Curt