I reinforced the mounting points for the flap and stabilizer control horns. Cutting off the covering, using epoxied 1/32" ply top and bottom over the wires stuck into the flaps and elevator. The geometry of my Cardinal wound up with the flaps orientated slightly up when the horn is vertical. To compensate I bent both flaps down. The reinforcements I made, allowed me to do this, no problem. When the flaps are horizontal the horn is canted slightly forward, which is actually a plus I believe, creating a better geometric relationship with the bellcrank. Not an ideal setup but o.k. (It's an ARF!) Tom Morris control horns work something like this. The dogleg in his horn also compensates for the slight discrepency in elevator movement/flap movement. Canting the control horn forward slightly improves the up down equalization of the flap movement. Without the dogleg in the Tom Morris system the discrepency in movement rate for the elevator is still built in. Nothing new about that. The majority of our stunt planes are like that. If the pushrod was too long I would have done something like you did. I always prefer adjustable controls and put them in kit built and scratch built planes. But this is an ARF so in this instance I took the easier way. Of course it's possible to make some corrections at the handle.
A further note on the controls-- it seems to me that the wire in the control horns is softer than our grade of music wire. May turn out to be too maleable, creating other kinds of control weirdness. Since no one in my club mentioned this. I let it go. Easy enough to stick in $15 dollars worth of good quality control horns though. Don't have to open up the wing for that. I'll leave this for my next ARF, if it turns out to be an issue.
If this Cardinal flies real well. I would consider opening things up next time and doing the controls right. Even going to an ARC. Certainly less work than doing a kit. The fuse construction intrigues me. Lots of hole cutouts under the covering back of the wing. Bobby Z (Bob Zambelli) who did much of the final engineering work to ARF the Cardinal, mentioned something about ply in the fuse, and the need for cutouts to avoid a tail heavy condition. The rear of the Cardinal is quite rigid for a profile. The engineering here might be spot on and not talked about enough. Flexi-flyer profiles, especially in profile stunt planes, happen. The longer tail moment aggravate this condition. Larry Cunningham's Mo-Best article on the PAMPA website discusses the use of 1/64" ply over a cutout/strut construction. This to aid rigidity. When building my scratch built planes I use fairly hard balsa for the fuse and cover with silkspan. The old fashioned way. Just ordered some carbon mat and will use on my kit built Primary Force. Bob Zambelli probably used a variation of the Larry Cunningham technique for the ARF and ARC Cardinal.
For around $100 we're getting a heck of bargain, anyway you look at it. Obviously the planes can be adjusted with this and that to fly extremely well. In Beginner, Intermediate and Advanced, ARFs dominate. At least in contests I flew in last year. My homebuilt planes were fun, but did not fly as well as the best of the ARFs. Mostly this was a function of the designs I chose to build and fly. They were more sport plane than serious stunt plane. The new projects on my board will be a mix of traditional stunt ships and home designs intended for competition. Since I will fly Intermediate next year, what the heck.
Building a kit or from scratch allows the use of better materials, upgrade in controls, improved covering, epoxy, more carefully selected bawsa. I really didn't like the look of the wood, for instance, used in the motor mounts of the ARF Cardinal. Didn't look like rock maple. (Maybe it was.) Also, I don't know what kind of glues were used, didn't see any evidence of epoxy. Don't know about the grade of the ply reinforcements. On the other hand the all up weight of my ARF came out at 44 1/2 ounces with the LA 46, tank, ready to go. Not bad at all for bird this size.
Topic: Brodak Cardinal vs. Sig's Primary Force (Read 9210 times)