GimbalFan
Elite Veteran
Location: Copter County, Nv
| Here's a useful idea about transmitters & RC helis that's actually been around for quite awhile. For those who're new to RC helicopters, it's a concept worth considering. For heli pilots who fly with Mode 1 or Mode 4 tx's -- unfortunately this tool won't be of any use to you because only Mode 2 and Mode 3 tx's have their elevator and aileron (cyclic) controls on one stick.
 . . . . .  A Ring on a Mode 3 (lefty) TX . . . . . . . . . . Stick Modes . . . . . . .
After seeing a couple of them at the field, I made a cyclic stick limiter ring such that the stick throws on my 7CHP are still 100% at the 3, 6, 9 & 12 o'clock positions, but limited at the corners. I was then able to adjust my tx's servo end points on both elevator and aileron up about 22% before I began dragging the shoulder of the swashplate against the mainshaft on my Rap 50.
As it turns out, the large servo wheel that comes with Futaba servos (9252's and others, part# FUTM2035) is exactly the right outer diameter for the 'seat' at the base of the gimbal of a 7CHP, for some other Futaba tx's and even for some non-Futaba tx's -- thanks to ChuckHager for that discovery. The servo wheel even has a slight bevel on the outer edge making it easy to press securely into place for flying helis and pop quickly back out for flying planks.
After measuring the stick throws at the base of the cyclic stick, I put the servo wheel in a drill press and drilled a 7/8" (22mm) hole in the center. I used a 13/16" (21mm) cylindrical sanding drum to smooth out the cut and bring it out to just the right inner diameter for the stick throws on a Futaba 7CHP, about 29/32" (23mm). I also beveled this inside hole about 40 degrees so that the tx stick would have a flat seat to rub against.
In the 1st and 2nd pics above you can see the concentric guide ridges on the 'bottom' and the beveling on the outside edge that are part of the original servo wheel mold. The concentric ridges are useful for keeping the inner hole round & centered as you enlarge it to fit your stick throws. The outer diameter of the servo wheel will fit a few other models and brands of tx's as well.
Some prefabbed limiter rings attach instead to the cyclic stick itself between the locking parts of the stick height adjustment. Either one accomplishes the same thing, but this method allows for quicker removal for plank flying.
When using one of these rings, GREAT care must be taken in the tx setup to confirm ZERO binding of the swash frame shoulder on the mainshaft, AND on ALL the linkages and ball link ends on the entire rotorhead, at ALL cyclic and collective stick positions.
I have 22% more swash angle available now at the 3, 6, 9 & 12 o'clock stick positions than I did when the tx stick's 'corners' were my limiting dimension for setting the aileron & elevator endpoints on my tx. Although this seems to be okay on a Raptor 50, it may be too much swash angle for other helis.
I recommend backing off at least 5-10% on your tx's elevator & aileron servo endpoints from the start of swashplate binding until you're absolutely SURE your bird will be happy with the greater angles.
_____
We have the good fortune here in Las Vegas of flying alongside all 3 Szabo Boys, and both Alans (Sr & Jr) along with Jeff Fassbinder of Thunder Tiger were at the field the day I tested this new setup.
Alan Jr was sure that the greater swash angle (even just shy of binding against the mainshaft) would not overly stress the linkages on a Rap50's head when using the ring. Nonetheless, for the first test I backed off about 10% on the elevator & aileron endpoints (2 degrees of swash angle). Nice.
Then I swapped out the 30g black paddles for 20g greens. NICE.
Then I bumped the endpoints back up to just shy of binding. NICE!!!
_____
This ring has worked out real well for maximizing swash angles. They're a good idea for anyone who's concerned about binding while 'in the corners'. Thanks to ChuckHager for the original idea and the servo wheel suggestion, to Eric_B for his accurate numbers on swash angle and to Alan Jr for his linkage assessment (and for lots of other answers over the past 6 months).
Did I mention that Alan Jr and Danny both use stick limiting rings?
They do, but whereas this is a hardware ring, theirs run as software - between their ears - because they're that flippin' good.
As for me, I'll use the ring. (Yes, that tx is a lefty -- don't ask.)
op-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-thwõp-t |
