-
There is no better time to show your support for SuperCub.Org than during our annual calendar campaign! All the details are HERE
Building an Experimental PA11
- Thread starter Dan Gervae
- Start date
Dan Gervae
FRIEND
Upper Peninsula of Michigan
I have elevator trim tab on balanced elevator with Ray Allen Electric Servo....I get 14 degrees up and 14 down....wonder if that’s enough ??? Seems like it would be, just wondering if anyone had done it before
cubdriver2
FRIEND
upstate NY
I have elevator trim tab on balanced elevator with Ray Allen Electric Servo....I get 14 degrees up and 14 down....wonder if that’s enough ??? Seems like it would be, just wondering if anyone had done it before
Why no jack screw? The difference between a cub and everything else is a trimable stab
Glenn
Dan Gervae
FRIEND
Upper Peninsula of Michigan
ugh, I know Glenn, I’ve been back and forth in my head so many times about this one. So many guys told me they like their trim tab fine....and others wish they had put in jackscrew. I keep thinking...I’ve made up my mind and done all the work to go this route....then I have second thoughts. My Tcraft trim works good....but it’s not tandem....it really wouldn’t take that much welding to put the jackscrew in....(my nice epoxy primed fuselage) lol. I’ll have this coffee and think some more.
cubdriver2
FRIEND
upstate NY
Sorry, you didn't need that monkey wrench thrown in right now. My J4 has a tab on the left elevator and also works fine, but I always wonder if I could get slower with a movable stab? But the J4 lands really slow now. Never happy, always looking to improve.
Forget that I mentioned the screw :lol:
Glenn
Forget that I mentioned the screw :lol:
Glenn
Linear actuator. Easier than a jackscrew. No trim cables to fuss with.
Sent from my iPhone using SuperCub.Org mobile app
Sent from my iPhone using SuperCub.Org mobile app
Attachments
Dan Gervae
FRIEND
Upper Peninsula of Michigan
Is that an SQ2 system? I like that!
Last edited:
skywagon8a
MEMBER
SE Mass MA6
A trim tab will work. Any time that the elevator is not streamlined with the stabilizer there is extra drag. A trimming stabilizer eliminates that drag. If you do not care about getting the most available speed out of your plane, go with the trim tab on the elevator.
Dan, here's my actuator set up and almost ready for cover. The vertical tubes in the airframe are critical for lateral stability. Fore-aft is determined by the stab. Up-down is all on the actuator. The little unattached eye on the back is a string potentiometer for a digital trim position indicator.
Hopefully Bill Rusk or others will chime in on how they installed similar actuators in their Javron Cubs. More examples and different ideas are always good.
Sent from my iPhone using SuperCub.Org mobile app
Hopefully Bill Rusk or others will chime in on how they installed similar actuators in their Javron Cubs. More examples and different ideas are always good.
Sent from my iPhone using SuperCub.Org mobile app
Attachments
Last edited:
cubdriver2
FRIEND
upstate NY
Has anyone just mounted a small gearmotor back there to run a belt/cable to just turn the stock pulley on the jackscrew?
Glenn
Glenn
or just take the pulley off and hook the motor output shaft direct to the jackscrew?
Dan Gervae
FRIEND
Upper Peninsula of Michigan
Thats pretty much what bill rusk did on his Javron
skywagon8a
MEMBER
SE Mass MA6
Electric motors do not have much power when operating from a dead start. They would be much better in this type of application if they had a reduction gearing/belt pulley arraignment where the motor could get some RPM while doing it's work.
Last edited:
Southern Aero
SPONSOR
kcco/1ga2
Glenn
I haven't found a satisfactory way of driving the jack screw and leaving the manual trim in place............. need some kind of clutch/disconnect ...... I have experimented with several gearmotors but haven't found a lighter one that has enuff power to work under and air load. I have also been working on incorporating a Mitchell trim motor assembly from some old Piper Comanche Senaca, etc. Little heavy so have been working a modified gearmotor with same working principal. Will post something later on it if I get it to work properly. Maybe someone else has already done this and can shed some light?
I haven't found a satisfactory way of driving the jack screw and leaving the manual trim in place............. need some kind of clutch/disconnect ...... I have experimented with several gearmotors but haven't found a lighter one that has enuff power to work under and air load. I have also been working on incorporating a Mitchell trim motor assembly from some old Piper Comanche Senaca, etc. Little heavy so have been working a modified gearmotor with same working principal. Will post something later on it if I get it to work properly. Maybe someone else has already done this and can shed some light?
thousands of high torque startup motors out there like this.https://www.amazon.com/dp/B00NMDPQA...t=&hvlocphy=9020859&hvtargid=pla-323303013812
gbflyer
Registered User
PAGS
Can’t recall fooling with the trim much on the -11 we had. Had the -18 balanced tail, understand the Pacer width tail is the best.
Certainly not a moose hauler. I’d think the Ray Allen servo and a tab would be a pretty simple and light solution. Works good on our current S7S. I doubt we use 5 degrees of the available deflection.
Certainly not a moose hauler. I’d think the Ray Allen servo and a tab would be a pretty simple and light solution. Works good on our current S7S. I doubt we use 5 degrees of the available deflection.
Southern Aero
SPONSOR
kcco/1ga2
Yup, quite familiar with them ......... have quite a few. Would work fine but I want to be able to disconnect from the drive so I can manually trim. The Mitchell type have a spur gear that is disconnected when power to the drive motor and solenoid is removed allowing you to still manually trim. I am experimenting with that kind of disconnect with one of these gearmotors
Gordon Misch
MEMBER
Toledo, Wa (KTDO)
Why do you want manual trim also? Redundancy? Fine adjustment? Just curious, thanks!
Southern Aero
SPONSOR
kcco/1ga2
Yes to both! :lol:
Gordon Misch
MEMBER
Toledo, Wa (KTDO)
Interesting. I will be helping a friend with an experimental -12, and I was planning to recommend to him an electric trim similar to what Stewart used. That's why I asked.
So my follow-up question is, why the need for manual "fine adjustment"? The higher load capacity linear actuators have slower travel rates, which I think might be why Stewart's actuator has such a high force rating. I think.
Calling Bill Rusk - - what is the travel rate of your electric trim system, and do you have issues with setting the trim "exactly" where you want it?
Redundancy, to me, isn't important because at least in my -12 I only touch the trim for changes in loading.
Edit: I think that cruise would be the only flight regime where an "exact" trim setting would be desirable. But in that regime a small change in engine power setting can achieve approximately the same effect as a small change in trim setting. Or I just set my arm on my lap so there is a slight stick pressure.
Not trying to be adverse, just trying to envision an optimal solution. Thanks - -
So my follow-up question is, why the need for manual "fine adjustment"? The higher load capacity linear actuators have slower travel rates, which I think might be why Stewart's actuator has such a high force rating. I think.
Calling Bill Rusk - - what is the travel rate of your electric trim system, and do you have issues with setting the trim "exactly" where you want it?
Redundancy, to me, isn't important because at least in my -12 I only touch the trim for changes in loading.
Edit: I think that cruise would be the only flight regime where an "exact" trim setting would be desirable. But in that regime a small change in engine power setting can achieve approximately the same effect as a small change in trim setting. Or I just set my arm on my lap so there is a slight stick pressure.
Not trying to be adverse, just trying to envision an optimal solution. Thanks - -
http://www.tcwtech.com/Safety-Trim-Page.htm
Actuators will use the 10A model. High speed-low speed controllable and the low speed rate is user adjustable at the module.
Actuators will use the 10A model. High speed-low speed controllable and the low speed rate is user adjustable at the module.
Last edited:
Olibuilt
MEMBER
Montreal, Canada
I have about the same setup as Bill Rusk and I love it. No pulley or cables. Very simple. About 17 seconds on the ground.. Easy to trim perfect.
I can't really see the purpose of having redundancy in a Cub trim system..? Worst case scenario is almost really a non event.
I can't really see the purpose of having redundancy in a Cub trim system..? Worst case scenario is almost really a non event.
PerryB
FRIEND
Chico, CA
Just power it through a pull-able (new word) circuit breaker, so it can be readily disabled should a switch stick.
Gordon Misch
MEMBER
Toledo, Wa (KTDO)
Stewart, could you please give an operational report on this system when you've flown it a bit?
Dan Gervae
FRIEND
Upper Peninsula of Michigan
Yes, just run the positive wire to a toggle switch ahead of the rocker switch so it can kill the juice if it sticks
PerryB
FRIEND
Chico, CA
Just curious, is your plane somewhat aft on the CG? It surprises me you go to full nose down for takeoff. Or does that have something to do with a modified thrustline?
Slow speed might make sense for the RV guys who are all about going fast but I'm confident the faster speed will be fine in the Cub. It isn't that fast. And I do like the three second time limit. Nobody wants runaway trim and the little stick top switch is the weak link in the system.
