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Bellcranks

Stuka Stunt Main Forum · 10 of 10 known posts recovered

Crash2much · Feb 09, 2004 07:02 PM

#0 source
LAST EDITED ON Feb-09-04 AT 07:35 PM (CDT)
 
This is kinda a follow up on my post yesterday. I tried putting a 4" Sig Bellcrank in my Tanager wing but I am not happy with the way it fits. There just isn't that much clearence from the LE. What is the opinion of the old Veco or Perfect cranks? I have used them for years. I asked Tony of T&A Hobbies fame and he bent the crank back and forth in a unconventional manner and claimed that I would have Bellcrank failure if I persisted in using one of these? I assume this is what some people refer to as "butterflying"?

Bill

I have no claim to fame, I build more planes than I fly, collect more kits than I build. That about says it, right?

Bill Little · Feb 09, 2004 07:30 PM

#1 source
LAST EDITED ON Feb-09-04 AT 07:32 PM (CDT)
 
Bill,
Move the mounting point back for clearance of the Sig bellcrank, that would be the best cure....... if that isn't possible for some reason, use a 3" Brodak Nylon.
The old metal Veco, Fox, and Perfect, while good in their day, are not as strong as today's products.
Bill <><

Disclaimer: I am neither a NATS Champion (yet), professional engine reworker, engine producer, column writer, Hobby Shop owner, *rockeet* scientist, nor otherwise. Just an old Advanced flier.

LNeumann · Feb 09, 2004 10:49 PM

#6 source
What Bill suggests in moving the mounting point back will work. You said it is "close" to the leading edge. How close? If it clears, that is all that you need. If you need to move the mounting point back just a little, do it. And, you can always cut the ends off and drill new holes and make it a 3 1/2 inch belcrank. Just make sure the new holes are equidistant from the center. Some belcranks even have a second set of holes drilled in them for just such a purpose.

Leonard Neumann

Crash2much · Feb 09, 2004 11:11 PM

#7 source
Leonard, I have about 1/16th of clearence if mounted as per the plans.

Bill

I have no claim to fame, I build more planes than I fly, collect more kits than I build. That about says it, right?

LNeumann · Feb 09, 2004 11:22 PM

#8 source
>Leonard, I have about 1/16th of clearence if mounted as per
>the plans.

Is that a problem? All you need is for it to clear. If it does, you are OK. And if you are squeemish about this, move the mount back a sixteenth of an inch and you will then have an eighth of an inch clearance. That should be totally adequate as long as you don't have height problems.

Leonard Neumann

Crash2much · Feb 09, 2004 11:30 PM

#9 source
Leonard, maybe its more intimadating because its a 4" crank? I have always used 3" cranks. It just looks freakish. I do know that I will have to slot out quite a few ribs close to mount if I go ahead and use it.

Bill

I have no claim to fame, I build more planes than I fly, collect more kits than I build. That about says it, right?

LeagueCityRalph · Feb 09, 2004 07:35 PM

#2 source
Have you considered the old Hi Johnson Circular Bellcranks? You don't get the same leverage (as a 4" B/C) at neutral, but you don't need it there. But the lever arm is constant so as control deflection increases, you don't lose much, either.

Ralph Wenzel

Crash2much · Feb 09, 2004 07:39 PM

#3 source
Ralph, as a matter of fact I do have have a bunch of the old Hi Johnson cranks, standard as well as the fulcrum type. I have been hanging on to these as more of collectable? items rather than intending to use them.

Bill

I have no claim to fame, I build more planes than I fly, collect more kits than I build. That about says it, right?

Steve Helmick · Feb 09, 2004 08:35 PM

#4 source
I have been told that the Hi Johnson bellcranks had been known to split at the spot welds (?) and cause problems. I like Brodak, Tom Morris or Windy bellcranks. Sig's BC's are certainly safe and inexpensive, but the 4" is heavier than it needs to be. Steve

LeagueCityRalph · Feb 09, 2004 08:46 PM

E-w-w#5 source
I hadn't heard of that problem, but I've been way too inactive for a while. I may still risk one Noblarf, just to see . . .

Ralph Wenzel