News:


Advertise Here

  • January 25, 2022, 12:59:40 AM

Login with username, password and session length

Author Topic: 4" Bellcranks, are they necessary in Classics??  (Read 3547 times)

Offline Jim Pollock

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1048
4" Bellcranks, are they necessary in Classics??
« on: June 23, 2007, 09:24:15 PM »
Guys,

I have used and others have used 4" Bellcranks in .35 sized airplanes that were originally flown with
3" Bellcranks.  I have even made a 3.5" Bellcrank and used it in a Classic airplane.  I think that 3.5" is
really as large of a bellcrank that is needed for a 50-56" span classic.  I think the more important value
in a bellcrank is that amount of control throw built into it.  Example, a slow enough control system can be
built with a 3.5" bellcrank and a 9/16 throw.  What do y'all think, anway........

Jim Pollock    :!  H^^

Offline Bill Little

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12781
  • Second in COMMAND
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #1 on: June 24, 2007, 12:14:41 AM »
Hi Jim,

For some reason, I like Tom's 3 1/2" bellcranks in the "standard Fox .35 size" Classic plane.

I found it interesting when a couple weeks ago, Kent Tysor flew my "restored" Charles Parrott P-47.  A pretty good sized "35 Classic".  I built it in '94, flew it in Classic for a year or so with a Fox 35.  Not enough engine, so I left it alone until a little over a year ago.  When I built it, I used a 3" Sig nylon BC, and some Top Flite horns I had.  It is now about 4 oz. lighter, and has a T&L McCoy 40 in it. 

Anyway, after Kent flew it, he remarked that he just couldn't fly it himself on a regular basis.  The controls were just too fast!  I was used to it, so it didn't bother me.............. but everything I have built of a serious nature in the past 10 years has had at least a 3 1/2" BC and "modern horns".
Big Bear <><

Aberdeen, NC

James Hylton Motorsports/NASCAR/ARCA

AMA 95351 (got one of my old numbers back! ;D )

Trying to get by

Online Dennis Adamisin

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 4112
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #2 on: June 24, 2007, 07:35:07 AM »
Jim:
A lot of the classic plans show very short horns, sometimes on inner holes of bellcrank... mechanically they are a disaster!  Thus I think one of the best things you can do for most classic designs is to give them a modern control system.  For me that includes using the 4" cranks with the 15/16" (outermost) throw to a 15/16" elevator horn, flaps usually slower.  If the classic bird did not have room for a 4" crank then..... I guess I would readjust everything so the outputs came out the same.

Denny Adamisin
Fort Wayne, IN

"Dear Lord, please keep your arm around my shoulder - and your hand over my mouth..."

Offline Jim Pollock

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1048
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #3 on: June 24, 2007, 07:15:34 PM »
Dennis,

About your saying at the bottom of your posts.  One day in the summer of 1972 you were in fact the
best Model Pilot in the United States!  Anyone that could beat Al's Sea Fury with a Hurricane had to be
the best! I guess that particular day was akin to the day in 1959 that Billy with his Ares beat Bob Palmer
and the new version of the Thunderbird for the walker cup.

Jim Pollock   8) 

Online Dennis Adamisin

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 4112
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #4 on: June 24, 2007, 10:03:37 PM »
Jim P:
Thanks.  I believe in the early 1960's you will also find the name of a Mr. Gerry Cipra, who I believe earned the trophy as a JUNIOR.  And yes, he WAS that good!

I won Junior in 1969 with my Hawker Typhoon, in 1972 I flew my Fouga Magister in Senior & the Walker Cup.  Al was then, and still is the leading proponent of semi scale CLPA, we spent a lot of time chewing over this and that.  I still think the Sea Fury was the single most impressive CLPA model ever, but his new Bearcat looks pretty good too!

My tag line just lets me trash talk a little..!  8)

OK back on topic & CASE IN POINT: I am looking over Sheeks Swinger plan and the one thing I MUST change will be the controls.  The plans show the Pushrod going from #2 hole in the bellcrank to the middle hole of the flap.  Weak mechanically but not unheard of.  The killer is that it shows the elevator driven off the innermost hole off the flap, to the middle hole of the elevator; meaning the elevator travel will be 1/2 the flap travel - don't think Jack built his that way, and I for sure will not!  I will stuff a 4" bellcrank into it, reversed so front line is up (per Al!), and run a rod from the outer hole of the crank to the outer hole of the elevator.  I will then run a second rod from #2 hole in the crank to the outermost hole in the flap.  This should result in a 2:3 flap to elevator, and some pretty light bearing loads at all points.  However, I will also probably have to put a "hump" on the top of the fuselage to cover the longer horn!
Denny Adamisin
Fort Wayne, IN

"Dear Lord, please keep your arm around my shoulder - and your hand over my mouth..."

Offline Tom Niebuhr

  • AMA Member
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2787
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #5 on: June 25, 2007, 01:11:59 PM »
There is no doubt that the larger horns and Bellcranks, are much better because they have a better mechanical advantage. just remember that that the actual movement of the surfaces are due to the relative distance between the holes.

The only restricting factor, in some cases, is the available space.

Dennis,
Can't to wait to see your progress on the "Swinger"
I talked to your dad.. sound like you and Archie are both back! Boy, is that great!
AMA 7544

Offline John Miller

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1681
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #6 on: June 25, 2007, 04:19:59 PM »
There is no doubt that the larger horns and Bellcranks, are much better because they have a better mechanical advantage. just remember that that the actual movement of the surfaces are due to the relative distance between the holes.

The only restricting factor, in some cases, is the available space.

snip

I can't agree more with Tom. In most cases, a little figuring, as far as ratios go, and you can have about anything you want, with either size bellcrank. It's just more "automatic" with a larger BC.

Should be able to get what you want, Dennis, without having to have a bulge to clear the horn.

John Miller
Getting a line on life. AMA 1601

Offline Jim Pollock

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1048
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #7 on: June 25, 2007, 04:40:31 PM »
Dennis,


Do you happen to have a picture of the Fouga Magister?  I would really like to see that one.

Jim Pollock   ;D

Online Dennis Adamisin

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 4112
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #8 on: June 25, 2007, 04:46:34 PM »
do I have pix... don't encourage me!  LL~  LL~  LL~

Just teasin Jim, thanks for asking!
Denny Adamisin
Fort Wayne, IN

"Dear Lord, please keep your arm around my shoulder - and your hand over my mouth..."

Online Dennis Adamisin

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 4112
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #9 on: June 25, 2007, 05:04:17 PM »
John & Tom:
You are right, I can get the correct ratios, but to do so inside the low Swinger fuselage means using a 1/2" horn on the flaps, with corresponding short output off the bellcrank.  However, I get real anal about maximizing the mechanical advantage and reducing bushing loads.  Thus I intend to use the 3/4" output from the bellcrank to a 1" flap horn.  Unfortunately that is about 1/4" ABOVE the top of the fuselage, thus the "radome" bump, which should look right at home on the jet anyway.  You know the Type 13 radar used on the second production batch of the F111b... - HONEST!!!  n~
Denny Adamisin
Fort Wayne, IN

"Dear Lord, please keep your arm around my shoulder - and your hand over my mouth..."

Offline John Miller

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1681
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #10 on: June 25, 2007, 05:42:32 PM »
Go fer it Dennis. 'lookin' forward to seeing that plane at VSC.

John M.
« Last Edit: June 25, 2007, 09:17:24 PM by John Miller »
Getting a line on life. AMA 1601

Online Dennis Adamisin

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 4112
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #11 on: June 25, 2007, 08:45:44 PM »
BTW, just checked out the plans for Sheeks Ryan SC and Bob Millers "extended Gee Bee"  Both show the elevator pushrod set up to give LESS elevator than flap throw.  This cannot be right (can it???)

Denny Adamisin
Fort Wayne, IN

"Dear Lord, please keep your arm around my shoulder - and your hand over my mouth..."

Offline John Miller

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1681
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #12 on: June 25, 2007, 09:16:07 PM »
Ya know, Dennis, in the old days, we simply used 1 to 1 ratio for the flaps and elevators. Nowadays, with planes with a reasonable wing loading, we've found that we don't need as much flap as we used to use.

I was speaking with Gordan Delaney about this very subject, the other day. He and I both agree that most of our planes have about a 6 or 7 degree difference, at full throw. The degree readouts on my most recent plane is about 24 degrees flaps, and about 32 degrees for the elevator. It's a very good idea to use an adjustable elevator horn. Too much flap can make "swoopy" turns, as I'm sure you already know..

John
Getting a line on life. AMA 1601

Offline Bill Little

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12781
  • Second in COMMAND
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #13 on: June 25, 2007, 11:06:19 PM »
I remember hooking up a few planes back inthe day with the flap rod below the elevator rod on the flap hoen.  Seemed to work..........  Billy told me he always used more elevator than flap on his old I-beamers.
Big Bear <><

Aberdeen, NC

James Hylton Motorsports/NASCAR/ARCA

AMA 95351 (got one of my old numbers back! ;D )

Trying to get by

Offline Jim Pollock

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1048
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #14 on: June 26, 2007, 06:57:04 PM »
Hi Bill,

I think that a large percentage of planes used the old 2-3 flap to elevator ratio.  I know that many old sets of plans
shows them hooked up that way.  I even have my Shark hooked up that way and it flies magnificently!  Oh yea,
it weighed in initially at 58 ounces, so I guess it was light enough to use those ratios to good advantage.  Dennis, I bet everyone at the 72 Nats was asking what that plane (Magister) was suppose to be huh?

Jim Pollock   H^^

Online Dennis Adamisin

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 4112
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #15 on: June 26, 2007, 07:17:59 PM »
Yup.  Kinda hard to explain it was a model of a French trainer in Belgian Airshow Team colors.  However, one guy called it a Nobler....

Denny Adamisin
Fort Wayne, IN

"Dear Lord, please keep your arm around my shoulder - and your hand over my mouth..."

Offline Bill Little

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12781
  • Second in COMMAND
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #16 on: June 27, 2007, 02:50:42 PM »
do I have pix... don't encourage me!  LL~  LL~  LL~

Just teasin Jim, thanks for asking!


Check out Dennis knelling with the plane...... color coordinated!  Red tennis shoes, red pants, black shirt.  AND ALL THAT HAIR!!!!!!!!!!!!!!  LL~  LL~ 

I vaguely remember having hair! LOL!!!!!

BTW: GREAT looking plane. y1
 H^^
Big Bear <><

Aberdeen, NC

James Hylton Motorsports/NASCAR/ARCA

AMA 95351 (got one of my old numbers back! ;D )

Trying to get by

Offline Jim Pollock

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1048
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #17 on: July 01, 2007, 08:32:20 PM »
Bill,

Yes he did look quite exceptional in the Picture.  I don't know if he had already won the walker cup or not,
but he looked the part even if he looked a little young.  Also, for Dennis, I remember hearing stories about
Gery Cipra and that he could have been as dominate as Mr. Walker, but I guess he found girls and such.
Happens to lots of great flying young folk.  My buddy Derek Berry has gone through the girl stage and is now
back flying and getting better.  I expect him to win a Nats very soon.

Jim Pollock,,  every time I watch Derek fly a pattern these days my eyes look like this........ :o :o

« Last Edit: July 15, 2007, 07:37:19 PM by Bill Little »

Offline Jim Pollock

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1048
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #18 on: July 11, 2007, 07:39:20 PM »
Well,

Seems that I did opt for a Buck 4" Crank for the Akromaster.  I guess
4" Bellcranks are a handy thing to have around.  I sure like Brett's
design of the Bellcrank.  I guess being an Aerospace Engineer has it's
rewards.  Even if you don't get to stay at a Holiday Inn Express!

Jim Pollock   H^^

Offline Ward Van Duzer

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1288
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #19 on: July 12, 2007, 09:26:14 AM »
At the '92 Nats I was flying a "scale" Navy Nobler in heavy wind. During the build I was told that a Sig 3 inch BC and a Sig Horn (plastic upright, steel flap arms) was good enough for a 35 powered Nobler. Well, being inexperienced in flying in heavy wind I got caught in a heavy "wind-up" on my inside loops. As heavily as I could lean on my UP line it wasn't enough to keep the airplane in the tight loop, and it figure-nined on the pavement. THE END! Examination showed the plastic upright on the flap horn broke at the push rod hole. But even had that not happened, I am sure that I didn't have enough leverage on the BC to keep that loop from opening up. Probably would have pancaked anyway.

I will NEVER use a control system that "is good enough" again! If a four inch BC has more leverage than a 3, or 3 1/2 incher, guess what I'm going to use? And if it doesn"t fit, Move it! Wild Bill says it doesn't matter where the BC pivot is, The airplane flies off of the leadouts!

Ward
I hate spelling errors, you mess up 2 letters and you are urined!

Don't hesitate to ask dumb questions.
They are easier to handle than dumb mistakes!  Ward-O AMA 6022

Offline Bill Little

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12781
  • Second in COMMAND
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #20 on: July 15, 2007, 07:38:46 PM »
Bill,

Yes he did look quite exceptional in the Picture.  I don't know if he had already won the walker cup or not,
but he looked the part even if he looked a little young.  Also, for Dennis, I remember hearing stories about
Gery Cipra and that he could have been as dominate as Mr. Walker, but I guess he found girls and such.
Happens to lots of great flying young folk.  My buddy Derek Berry has gone through the girl stage and is now
back flying and getting better.  I expect him to win a Nats very soon.

Jim Pollock,,  every time I watch Derek fly a pattern these days my eyes look like this........ :o :o

Little Buddy (Derek) has gone through the marriage stage and is out of that now.  These guys are over 30 now!  I cannot believe it!  Aaron was talking with him Friday night, and I can't believe my son is 31..............  Derek's SON is winning contests now!!!!!  Let's see...... his Dad (Derek) is a NATS Jr., Sr., (Adv.??) and Jr. World Champ, his Grandpa (Dale) is a OTS and Adv. Nats Champ....... good "pedigree" I would say.

I was on the phone with Todd Lee today.  His son AJ will be going to the field with Dad(Todd) before long.  Then he can have two Grandpas with him (Archie Adamisin, Jim Lee) and a Great Grandpa (Big Art) and of course his own "Dad" (Todd), a multiple Nats winner and WC Sr. Team member.  These kids will not lack for the "help" they can get if they choose to be CLPA pilots.y1

My poor old son and grandson are REALLY behind the 8-ball!
Big Bear <><

Aberdeen, NC

James Hylton Motorsports/NASCAR/ARCA

AMA 95351 (got one of my old numbers back! ;D )

Trying to get by

Offline Al Rabe

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 194
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #21 on: August 10, 2007, 01:34:42 PM »
My reply to the original question is "NO".  There is way to much mystical BS about bellcrank size and ratios.  All of my airplanes until the BBQB had 3" bellcranks and racked up their share of NATs wins and flew in as much wind as anyone else.  anyone seeing my original Snaggletooth flying in the wind at the 1974 NATs finals would have to admit there was no problem with controllability.  I still use 3" bellcranks where appropriate.

Al

Offline Randy Ryan

  • AMA Member
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1768
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #22 on: August 10, 2007, 07:07:58 PM »
For my part, I don't think its so much a 4" bellcrank being too big as it is what works for you. I've gone to all 4" bellcranks because I've found is smooths out my maneuvers. It may not for someone else, but slow controls are what the Dr. ordered for me. I really like the fine resolution you get with the longer arms too.

Here are some shots of the control system I built for a GB Nobler I'm working on. I know, overkill, but with this setup I can adjust throws from absolute zero, so I can find out what the optimum differential and flap deflection are.
Randy Ryan <><
AMA 8500
SAM 36 BO all my own M's

Offline Jim Oliver

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1397
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #23 on: August 10, 2007, 09:28:10 PM »
In a word---"WOW".

Jim
Jim Oliver
AMA 18475

Offline Randy Ryan

  • AMA Member
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1768
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #24 on: August 10, 2007, 10:24:29 PM »
In a word---"WOW".

Jim

Is that good or bad?
Randy Ryan <><
AMA 8500
SAM 36 BO all my own M's

Offline Jim Oliver

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1397
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #25 on: August 11, 2007, 03:56:50 PM »
Randy,

I am impressed with the extent of the work you did to achieve full adjustability.   H^^

I think it would be great if you would write up the details and results for guys like myself.

Cheers,

Jim
Jim Oliver
AMA 18475

Offline Randy Ryan

  • AMA Member
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1768
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #26 on: August 12, 2007, 06:19:29 PM »
OK Jim,

When I get back to it I'll do that.
Randy Ryan <><
AMA 8500
SAM 36 BO all my own M's

Offline L0U CRANE

  • AMA Member
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1048
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #27 on: August 12, 2007, 09:52:01 PM »
We've all knocked this one around quite a bit...

If you take a 5" bellcrank, and make the pushrod radius proportional to a 3" bellcrank, and make the flap and elevator horns proportionally larger, --

YOU HAVE NOT CHANGED ANYTHING! It feels like the original model using a 3" bellcrank and the horns illustrated (or provided) in the kit.

The only change is that you have 'slowed down' the response, unless you change handle line spacing by the same proportion as the on-board pieces.

It isn't that hard to build your own bellcranks and horns - I've done mine for years, except when - rarely - commercially  available pieces were close enough (radius within 1/32", say).

The advantages to larger leadout and pushrod hole radii: The pushrods are under less load. If it takes 10 inch pounds of torque to turn the flap to 45, a 1" horn radius only sees 10 lbs load. A half-inch horn requires 20 lbs. THAT force must pass through the pushrods. 10 lbs? Sure. 20 lbs, well, er, uh, maybe...?

And, if you want the same 'response rate': adjust the spacing between lines at the handle.

One of the things I enjoy in this hobby is trying to nail such relationships before I cut wood, ply, foam, wind, or whatever. Seems to have worked, leaving only me to blame for how the models fly when judged...
\BEST\LOU

Offline tom hampshire

  • AMA Member
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 391
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #28 on: August 13, 2007, 07:27:49 AM »
The above posts are all correct.  BUT... It is humbly submitted that the missing part of the analysis so far is the ergonomics, meaning the hand movement necessary to generate a given control deflection.  Clearly, a 3 incher will give more angular bellcrank deflection for a given hand movement than a four incher.  This excess bellcrank rotation generates two undesirable effects, the first being that over rotation.  Once the bellcrank is past 20 or 30 degrees,  the effective moment arm of the bellcrank gets noticeably shorter.  The shorter the arm, the more force is required, and the less tolerant the whole system is to minor corrections.  Which leads to the major difficulty with 3 inchers, the controls are too quick.  Think of it in terms of control deflection per length of leadout travel, not per the angular rotation of the bellcrank.  Most of us have experience with some plane which had ultra quick controls.  Try one again sometime, and see how difficult it is to fly accurately with quick controls.  The slower controls make the whole setup easier to fly accurately.  So most of the poster so far haven't thought of it in terms of flyability, e.g. the comfort of the pilot.

Alan Hahn

  • Guest
  • Trade Count: (0)
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #29 on: August 18, 2007, 06:05:02 PM »
Tom,
Why simply going to narrower leadout spacing on the handle doesn't fix this?

Offline Bill Little

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12781
  • Second in COMMAND
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #30 on: August 19, 2007, 07:54:43 AM »
The above posts are all correct.  BUT... It is humbly submitted that the missing part of the analysis so far is the ergonomics, meaning the hand movement necessary to generate a given control deflection.  Clearly, a 3 incher will give more angular bellcrank deflection for a given hand movement than a four incher.  This excess bellcrank rotation generates two undesirable effects, the first being that over rotation.  Once the bellcrank is past 20 or 30 degrees,  the effective moment arm of the bellcrank gets noticeably shorter.  The shorter the arm, the more force is required, and the less tolerant the whole system is to minor corrections.  Which leads to the major difficulty with 3 inchers, the controls are too quick.  Think of it in terms of control deflection per length of leadout travel, not per the angular rotation of the bellcrank.  Most of us have experience with some plane which had ultra quick controls.  Try one again sometime, and see how difficult it is to fly accurately with quick controls.  The slower controls make the whole setup easier to fly accurately.  So most of the poster so far haven't thought of it in terms of flyability, e.g. the comfort of the pilot.

Hi Brother Tom,

I totally agree that the "old systems" are vastly inferior now that we have become familiar with the "new" systems"!

How many of us learned to fly with a 3" bellcrank, Veco horns, and an E_Z Just or Hot Rock which in relation to "modern systems" gave us HUGE handle spacings, relatively speaking.  It is SO MUCH easier, IMHO, to go to the new 4" BC and 1" to 1 1/2" horns than for a young flier to go to the "old set up".  A couple weeeks back, Kent Tysor flew mty Parrott P-47 complete with 3"BC, Veco Horns......  He said, "it looks real pretty in the air"!  (and that "he" couldn't fly it, too quick!)

Given that, there must be something to the "new" systems, right? ;D
(and don't tell me it's just because I have gotten older! I don't wanna hear that! **) **) **)  )
Big Bear <><

Aberdeen, NC

James Hylton Motorsports/NASCAR/ARCA

AMA 95351 (got one of my old numbers back! ;D )

Trying to get by

Offline tom hampshire

  • AMA Member
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 391
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #31 on: August 20, 2007, 06:39:22 PM »
Hi Alan & Bill - I don't know why a narrow handle spacing doesn't feel right to me... only that it doesn't.  If you want to slow down a set of to fast controls, usually you wind up with a front slider bar handle.  Funny thing, I wandered into the team trials about 15 years ago and got drafted by Mr. Tiahrt to be pit boss.  I learned that none of the entrants at that level used a handle with a slider bar.  All of the handles had the control hardpoints as close to the knuckles as could be.  My guess is that the excess overhang (Having the handle arms too far from your knuckles) gives excessive sensitivity around neutral.  Other opinions welcome.  Tom H.

Online Dennis Adamisin

  • 2019 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 4112
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #32 on: August 20, 2007, 08:04:34 PM »
I think Lou's comment on long horns and lower pushrod loads really nailed the issue.  H^^  Lower bearing loads = long lifed control systems.

Whether you use a 1" or 5" bellcrank, it is POSSIBLE to get the correct ergo relationship between hand movement and control surface movement, but you mght have to take some extreme measures.  I just find that with my fixed spacing handle, a 4" crank works pretty darned good - so I will continue to use those cranks and the longest feasible control horns I can.

BTW I use a DIFFERENT (smaller) handle for a bird with a 3" crank and just got another handle ready for a bird wih a 2" crank.  Then there's the Goldberg handles for the 1/2A's!

Denny Adamisin
Fort Wayne, IN

"Dear Lord, please keep your arm around my shoulder - and your hand over my mouth..."

Offline Ward Van Duzer

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1288
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #33 on: October 09, 2007, 02:41:54 PM »
Uh, the longer the lever, the less torque (muscle) required to move it. (other things being equal)

3 inch BC = manual steering.

4 inch BC = power steering.


among other things!


W.
I hate spelling errors, you mess up 2 letters and you are urined!

Don't hesitate to ask dumb questions.
They are easier to handle than dumb mistakes!  Ward-O AMA 6022

Offline Ron King

  • Moderator
  • Trade Count: (0)
  • Commander
  • *****
  • Posts: 354
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #34 on: October 10, 2007, 05:44:06 AM »
When I built my first Oriental, after returning to the hobby, I calculated the angular deflection of the 3 inch bellcrank versus the 4 inch bellcrank. I determined where I needed to drill the push rod hole based on these calculations to make the control systems equal and built the plane with a modified 3 inch bellcrank.

To this day, I cannot tell the difference at the handle when I'm flying. The controls in my classic Oriental move the same as the controls in my big ship. I want and need this similarity because I don't want to waste time getting reacquainted with each plane.

My .02,

Ron
Ron King
AMA AVP District 4
Wannabe Stunt Pilot since 1963
 Amateurs practice until they get it right; Pros practice until they cannot get it wrong.

Offline Paul Smith

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 5298
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #35 on: October 10, 2007, 09:18:27 AM »
Tom,
Why doesn't simply going to narrower leadout spacing on the handle doesn't fix this?

In theory this would work:

Use a 1" BC and 1" handle spacing, or use a 3" BC and 3" handle spacing.

The problem is that the smaller system developes more torque and wears out faster.  If a small system developes 1/32" of slop, it's worn out.  A big system can tolerate a much looser fit.

On a bellcrank, the input needs to be limited to +/- 45 degress, otherwise the output side goes flat.   It easier to keep big bellcranks within a smaller angle of movement.    However, this is why HUGE bellcranks don't work either.  A 6" BC would have such a small angle of motion that it would have no output, unless you used a 6"  handle.
« Last Edit: October 10, 2007, 05:54:19 PM by ama21835 »
Paul Smith

Offline Ron Merrill

  • 2013 Supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 279
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #36 on: October 10, 2007, 10:41:33 AM »
Mr. Randy Ryan, may i ask what mods you made to the GB Nobler fuse to reach your magnificent bellcrank setup? #^ #^ Ron.

Offline phil c

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2340
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #37 on: October 10, 2007, 02:06:13 PM »
the biggest thing I see is that using a larger bellcrank gives you the OPTION of slowing down the controls and, even bigger, reducing the pushrod and bearing loads.  If you use the exact same geometry on a 3 in. bellcrank setup and a 4 in. bellcrank setup the 4 incher puts a lot less load on the pushrods.  Also, as Tom points out, the smaller bellcrank reacts faster to a standard 4 in. handle and going to an adjustable handle with the lines attached outside your knuckles makes the control forces you feel go way up.  The overhang between the handgrip and the lines is just another lever- the longer it is, the harder it is to move the controls.  The old EZ Just got it almost exactly right for most people with only an inch or so of overhang.
phil Cartier

Offline Leo Mehl

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1954
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #38 on: October 18, 2007, 10:36:05 PM »
In the 60's we used very fast controls which meant that we had to stay at a constant attention during maneuvers. The total leadout pull from neutral was about one inch or less. I have built two classic planes lately and I went from an inch to about 2". What a difference this made as far as flying a classic plane. I have seen some of the Orientals that Don McClave has built and he still makes his controls fast. In any case the classic plane flys better with slow controls. Also most classic planes have shorter tail moments. y1 y1 y1 y1 y1

Offline doug coursey

  • Trade Count: (0)
  • New Pilot
  • *
  • Posts: 19
Re: 4" Bellcranks, are they necessary in Classics??
« Reply #39 on: December 13, 2021, 07:50:06 PM »
don still used 2 3/4 inch bellcranks in his stuka stunt with 45 degrees of flap and elevator....i know its old but i had to post this because im building a stuka stunt and going with an Okie 3 1/2 inch bellcrank. the wing is on the small side 47" wing span. 
« Last Edit: December 14, 2021, 06:24:10 AM by doug coursey »
AMA 21449


Advertise Here
Tags:
 


Advertise Here