News:



  • April 27, 2024, 03:28:02 AM

Login with username, password and session length

« previous next »
Pages: [1]   Go Down

Author Topic: BELLCRANKS SIZE AND PROPORTION  (Read 1408 times)

Offline Scott Jenkins

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 251
BELLCRANKS SIZE AND PROPORTION
« on: January 24, 2007, 11:48:30 AM »
Hi all I am getting ready to set up another production run of bellcranks. Normally I make only 2 inch bellcranks for the racing side of the hobby. but thought I would make and test some larger bellcranks for Stunt and combat and possibly some for 1/2 A and speed. Question is I know that most stunters are fond of 4" bellcranks but I do not know what the throw is on the pushrod end. One more thing my bellcranks are made from Carbon Graphite 2 and 3mm sheet. The 2" bellcrank will pull test at over 150 lb. I have yet to have one returned or hear of one failing. I will replace any bellcrank of my manufacture due to defect or failure of the bellcrank itself.

Scott
Logged
Scott Jenkins
AMA 43122
FAI F2C VOLUME 2 SECTION 4, 4.3.7
m) During the refuelling and the restart of the motor, and until the time when he releases the model aircraft, the mechanic must keep the model aircraft in contact with the ground by at least one point and with the centre line outside the flight circle. During that time the pilot must be crouching or sitting inside the centre circle. He keeps one hand on the ground and his handle and his lines as close to the ground as defined by the F2C panel of judges until the model aircraft starts again.

Offline Bob Reeves

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3415
    • Somethin'Xtra Inc.
Re: BELLCRANKS SIZE AND PROPORTION
« Reply #1 on: January 25, 2007, 03:00:21 PM »
Tom Morris bellcranks are typically not drilled so the user can locate the push rod as it suites him. Probably your best bet would get hold of 3 and 4 inch bellcranks from Brodak or SIG  and copy the measurements. All of mine are in airplanes, makes it a little hard to measure.
Logged

Offline phil c

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2480
Re: BELLCRANKS SIZE AND PROPORTION
« Reply #2 on: January 25, 2007, 05:50:16 PM »
Fox 2 in.  .325  .540
Fox 3 in   .375  .6  .825
Brodak 2 in.  .425  .610
Brodak 3 in.   .470  .7  .935
Brodak 4 in.   .470  .680  .920

The Fox bellcranks are moderately soft aluminum.  Never seen one break, but they can bend, which actually is a plus, since it acts as a cushion.

Just got some of John's bellcranks in. The 2 in. one looks like opaque nylon.  The 3 incher appears to be straight, unfilled nylon, and the 4 incher appears to be a fiberglass-filled black nylon, similar to many plastic motor mounts.  Haven't pull tested any of them to destruction.  The most likely problem with any molded crank would be internal flaws that won't show up until it is pulltested.  The 4 inch one is certainly stiff and strong enough by a quick hand pull test.
Logged
phil Cartier

Offline Scott Jenkins

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 251
Re: BELLCRANKS SIZE AND PROPORTION
« Reply #3 on: January 26, 2007, 06:35:02 AM »
Phil,
Thanks for the info what is your favorite size of Bellcrank. PM me and I will send you a sample as soon as the next production run is complete. Better yet if you have a particular style drawn up and want to try send it to me with dimensions and I will add it to the cut list. scojen@earthlink.net

Scott
Logged
Scott Jenkins
AMA 43122
FAI F2C VOLUME 2 SECTION 4, 4.3.7
m) During the refuelling and the restart of the motor, and until the time when he releases the model aircraft, the mechanic must keep the model aircraft in contact with the ground by at least one point and with the centre line outside the flight circle. During that time the pilot must be crouching or sitting inside the centre circle. He keeps one hand on the ground and his handle and his lines as close to the ground as defined by the F2C panel of judges until the model aircraft starts again.

Offline Scott Jenkins

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 251
Re: BELLCRANKS SIZE AND PROPORTION
« Reply #4 on: January 29, 2007, 10:33:55 AM »
Phil,
You have mail here at stunthanger.

Scott
Logged
Scott Jenkins
AMA 43122
FAI F2C VOLUME 2 SECTION 4, 4.3.7
m) During the refuelling and the restart of the motor, and until the time when he releases the model aircraft, the mechanic must keep the model aircraft in contact with the ground by at least one point and with the centre line outside the flight circle. During that time the pilot must be crouching or sitting inside the centre circle. He keeps one hand on the ground and his handle and his lines as close to the ground as defined by the F2C panel of judges until the model aircraft starts again.

Offline Al Rabe

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 193
Re: BELLCRANKS SIZE AND PROPORTION
« Reply #5 on: April 02, 2007, 10:22:43 AM »
Personally,  I favor bellcrank throws equal to the height of the used flap horn.  In the case of Tom Morris's flap horn, 1 1/4".  Tom's bellcranks have enough material to drill for 1 3/16", but 1 1/4" gets too close to the edge of his material.  Bellcranks with large throws are needed when particular designs depend on large control movement for lift.  I like the thought that Tom will drill his bellcranks for any throw possible within the physical limits of his bellcrank profile.  Replacing defective bellcranks?  After the crash?

Al
Logged

Offline Randy Powell

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 10478
  • TreeTop Flyer
Re: BELLCRANKS SIZE AND PROPORTION
« Reply #6 on: April 02, 2007, 02:02:03 PM »
I make my own.
Logged
Member in good standing of P.I.S.T
(Politically Incorrect Stunt Team)
AMA 67711
 Randy Powell

Advertise Here
Pages: [1]   Go Up
« previous next »
Tags:
 


Advertise Here