Two new ARFs/ARCs from Brodak

I now have the prototypes for two more of John Brodak's ARC planes - the Bi-Slob and the profile P-40.

The workmanship, fit and finish on both are absolutely outstanding.

I had to do some minor re-engineering on the two, mostly for added robustness, lightening and user convenience. The info has been sent back to John.

I plan on having the Bi-Slob at the fly-in, hopefully ready to go. I will use a tinted Brodak clear just to show the quality of the construction. Silk on the wings. If all goes well, we will have some fun testing it.

The P-40 is a .40 to .46 size, has a Cardinal-like airfoil and the numbers look quite good. It should be an excellent flyer.

For information regarding price and delivery, you must contact Brodaks.

As far as I know, both will be available as ARC or ARF but best to check with Brodak on that.

Bob

ps - anyone interested in seeing some pictures?

YES!

Here are a few photos - I don't want to take up too much space. If you want more (I have quite a few), e-mail me at and I'll send you the package.
Bob Z

Are the flexible lead-outs not bushed in the nylon belcrank? That bothers me.

Hi, Len - good point but I'm really curious about something pertaining to this. I have had braided leadouts fail when used with metal bellcranks but of all the applications with nylon or delrin, I have never had a problem and I haven't used bushings or tubing. My Viking, which pulls like a horse has absolutely no wear - the holes are still round after well over 300 flights. Same with my Euclid and Stuntwagon - no noticeable wear. Whenever I refinish or rebuild a plane, I always look for (bellcrank) wear but I've never seen any.
One thing to mention, however - I always force some grease into the leadout pivots - maybe that helps to prevent cutting through?
What have you found?
Bob Z

I have used solid leadouts almost exclusively. Same with Matt. He had some wear on the carbon fiber belcrank on his white Stuka after a bit over 1000 flights. It wasn't enough to become a problem yet, but enough that he didn't want to use it on a new one. My main concern on the leadouts, however, is not so much the wear on the belcrank as it is on flexing. I always say that anything that flexes will eventually break. Matt had the leadouts break on two planes using .025 solids. We attributed it simply to flexing.

When the flexible leadouts are attached in the way shown, there will be a certain amount of flexing, right at the belcrank, both from the back and forth movement, and also from the changing pressure of the line tension as it goes through the pattern. This is what we attributed the .025 failure to. And it is not big airplanes I am talking about. One of these was on a Still Stuka, OS 35S powered, on which both leadouts failed at the top of the overhead eight.

When you use the length of tubing that threads through the belcrank with the leadout inside it and then fold it over so both ends touch before swaging the leadout, you eliminate that flexing.

As I say, that is the part that scares me. Dan Winship used to demonstrate how he did this. He could hook up both leadouts using this method in about 30 seconds, so it shouldn't be a big issue to do this on the ARFs.

I have seen posts on this board stating that nylon tends to make a good bearing surface in this application. I have a grossly overweight (80 oz...ouch!)Sig Magnum I built in about 1989 or 1990 with lots of flights on it. A couple of years ago I got worried about this very thing, so I cut into the wing to check. NO WEAR VISIBLE, AND THE LEADOUTS WERE NOT FRAYED! Maybe there is something to it. I am still skeptical about the flexing, though, and haven't done one like that since, except on small, lightweight applications. But I have convinced myself about nylon and the lack of wear. But, did I use a nylon crank on my new one? Nope, Tom Morris phenolic and all the trimmings.

My findings regarding cable leadouts through nylon bellcranks would support Zambelli's findings. Examing bellcrank assemblies from crashed models, some with as many as 250+ flights, showed zero wear on the bellcrank, and the leadouts looked as new. Maybe this connection could be worn out, but I suspect the plane would fall apart before this assembly.

Solid leadouts are a different animal, and I have no data on them.

But the brodak jobs are supplied with cable leadouts, so no problem I think.

>Solid leadouts are a different animal, and I have no data on
>them.
>
>But the brodak jobs are supplied with cable leadouts, so no
>problem I think.

Solid leadouts do not need to be bushed. But I am still concerned about the flexing of the stranded leadouts. If they flex at that location, and I can't see how they would not with the belcrank movement, they will, eventually break. We have had crimped flying lines break at the crimps. Whenever they broke, it was always a strand at a time which we caught between flights so it never resulted in total failure. But the breaks also occurred at the wingtip end, not at the handle. Why there, I don't know, unless there was some flexing going on that I don't know about. But I would still be much more comfortable with bushed ends at the belcrank.

I personnally think that when a crimped line breaks it is because the line was damaged during crimping. I have only had one failure of a crimped line in all these years (during a pull test), but I have been convinced by the experience of others to quit crimping and start wrapping.

Crimping puts a hard point right at the crimp. If there is any flexing, it will take place at that spot. The failures we have experienced were with commercially crimped (Sullivan) lines. I don't think this problem should exist with leadouts that are properly bushed. Dan Winshuip, for instance, crimps his onto the belcranks that he makes, but he uses the bras tube bushing on them, also. The unbushed ones, however, still bother me.

Len,
I think you will find that the Bi-Slob will not last long enough to wear through the belcrank. I think most Bi-Slobers here would bear me out on that (that is if they fly the plane in the Bi-Slob way).

Yes! Finally went to a profile body and that took care of hauling the thing home in a bag.

One thing nice about a Bi Slob's control's is the belcrank can be inspected by giving full up or full down, I know I have three and one almost broke from a bad leadout, but I saw the broken wire when I was cleaning the plane( LUCKY)and its easy to replace.. See Ya NEAL

As some are curious about the weight, I weighed the airframe - that is, all the wood, without any hardware - it's around 12 ounces, +/-.
The Bi-Slob will be covered with silk and clear doped with tinted Brodak clear. Power will be a piped Ro-Jett .60.
Bob Z

>........ Power will be a piped Ro-Jett .60.
>Bob Z
Bob, Dont forget to sweep the wings, s'sonic aircraft fly better that way.
Roger

The Brodak web page doesn't seem to have info on the ARFs/ARCs. Did I just not see it? Are there pictures and prices for all the Brodak ARFs/ARCs somewhere?

Ron - try again. They should be on the website. If not, contact me as I will be speaking to John today.

bob Z

>Ron - try again. They should be on the website. If not,
>contact me as I will be speaking to John today.
>
>bob Z

Bob, Ron,
They are there (all seven of them).
Click on march 18, 2004 , ARF models ....., more info.
then click on images for new models.
R....

Found 'em

Thanks!