Hi ,

Well , I may as well strike while the iron is hot 

I wish to use carbon fiber pushrods with adjustable Sullivan Golden Rod clevis' .
I can see where this might be to advantage when trying to trim out a profile stunter , but my concern is with the full fuse style ships .
What do I do to make the flap horn / elevator horn linkages accessible for trim adjustments ?
Do I have to cut into a nicely finished model to get at the inner mechanisms ?
I guess if the model is near perfectly square , it should fly somewhat decently , but what if not ?
I'd really rather tinker , than do a whole new renovation 

Thanks ,

Rob Killick

Sure wish you'd reconsider the clevises; why risk a ship? For only a little more $$, you can get the almost-bullet-proof Rocket City Ball Links. Clevises break, the pin falls out, etc. I've never heard of a properly-installed Rocket City unit failing. It may have happened, I've just never heard of it.

Ralph

previous comments correct, search for some of Randy Powells stuff, hes the hatch man, lol, he has one I really like, no tools and it looks like some kind of kinky speacial trim thing,

Look at the adds for Radio South. They sell titaium insert ends and carbon fiber shafts for control linkage. Another idea is the tie rod ends for r/c cars. They are right and left hand threaded on each shaft. Then it's just a wrench adjustment to shorten or lenthen the push rod.

Don

Again, why not just go with Tom Morris stuff, well proven hardware.

James

The photo below shows the system I've been using for some time. The normal style bellcrank inside the wing is fixed to the shaft which extends through the bottom (or top if you want) of the wing. The alloy arm is locked to the shaft so it's turned by the bellcrank. The flap drive is in the right hand slot and of course elevator on the left so each can be adjusted individually. There's a captive nylock nut underneath so the allen head bolts only need to be loosened a little to slide in the slots, no spanner needed to hold the nut. Both pushrods (CF for the elevator) connect to the balljoints with a 4-40 turnbuckle (left and right hand threads) for length adjustment.

The first time I used this system I made a dogleg adaptor to hold the flap balljoint directly over the shaft which isolated the flaps from any movement. I did this simply to set the elevators for the travel I felt comfortable with and then began dialing in the flaps until any trace of a stall in the hardest turns was eliminated. Any more flap than that is just added drag. What really surprised me even with the smallest amount of flap movement was how much the load at the handle increased.

What is the source for the straight arm with slots, and the captive nuts?
Do you have any pictures of how you fixed bellcrank onto shaft?
I have always though about doing something like this because I think it weakens the center wing section having the pushrod go thru the sheeting.

The easy way is to use the DuBRO Turnbuckles, PN #2157 (or #2156 w/wrench). These are square stock, threaded LH and RH on opposite ends. Then just thread one end into the Ball Link (which is NOT pre-threaded, BTW) and the other end into the pushrod. Cut an adjustment slot in the side of the fuselage just large enough to swing the wrench. Be sure to wrap the pushrod end with Dental Floss or thread and CyA or epoxy to prevent splitting!

Ralph

 

Hi ,

Allright ...

You gentlemen have sold me on the idea of ball links . I'm familiar with them , but only in my mechanical profession .
I see Control Line Central offers two styles of ball links (a B-57 and a B-87) . No hole sizes are given on the CLC site .
Can anyone let me know if the the ball links are pre-threaded , left hand or right hand , or do the pushrod inserts self tap into the ball link(s) ?
I'm sure I need two of the adjuster nuts per pushrod / horn assy. Are they RH and LH thread also ? The flap/elevator horn clips secure the ball link to the horn , correct ?
Maybe someone could be so kind to give me a general description of what I  would need for a control system set up ?
Thanks for all the help I really appreciate the time you all take out for me  I try and save as much of the info I can glean from this site and it has helped me a great deal .

Thanks again ,

Rob Killick

Hi Rob,

The B-57 links are plenty in my book for all but the heaviest BIG stunt ships. 

At the BC (Tom Morris unit) I use a ball link and a brass cone stand off.  It allows the pushrod to exit at any angle you would ever probably run into.  I do put a brass #4 washer under the head of the socket head 4/40 bolt.  I thread the hole in the BC and then use a nut on the bottom which is CA'd or epoxied to the BC.  Tighten everything down and use lock tight on the bolt.  You will be using one threaded insert there.  The ball links will pretty well seal to the threads, they are not tapped.  It can take some obvious effort to turn them if they have been on for any length of time!

(2) ball links, (2) threaded inserts  Since the flaps are always set at 0-0, RH threads are all that are needed.

At the flap horn, I have gone to the twin upright ones where the ball links are between the uprights.  Still use 4/40 bolts and the horns are threaded if you specify ball link usage.  You will need a threaded insert on that end and a ball link. (the flap rod is done)

(2) ball links, (1) RH thread insert, (1) LH thread insert, two 4/40 socket head screws and a couple washers are neded to make up the elev. push rod. 

Materials: (1) Morris Bell Crank, (4) ball links [B-57], (3) RH inserts, (1) LH insert, (1) brass cone standoff, socket head bolts, washers.  Also, as someone mentioned, use kevlar thread, dental floss, CF tow, or something similar to wrap about 1" of end pushrod end, and I always use J.B. Weld to make up everything.  (take a bolt and scratch up the inside of the CF rod to help adhesion and use a pipe cleaner dipped in acetone or lacquer thinner to clean out the inside of the rod)

I make a hatch that is big enough to get an ignition wrench into to turn the LH insert at the elev horn, and also to loosen the bolt of the adj. elev. horn.  This will give a length adj. elev. push rod, and an adj. elev. throw.  All you need!

Mongo

Guys,

The advantage of the LH/RH thread set up is that you are not limited to half-turn adjustments, and you don't have to take anything loose to make the adjustment.

Granted, it is a little more effort to fabricate the unit............especiallythe first time you do it.

Cheers,
Jim

Hi Jim,

Out of curiosity, why is it harder to fabricate?  All the parts are available, just glue them together the right length..........

Mongo