Pilot RC 122" Extra 330SC

[Joe Hunt]

This is interesting. I have never heard of using different holes on different servos in a multi servo wing panel. I have always used the same hinge points on all connections and have never had an issue.

Enlighten me @49dimes Maybe I will run into a situation where this will help solve an issue one day if I know how to correctly make it work.

I was asked to explain some of this in a video in the last review (of the AW Yak55), here's that video:

 

[dhal22]

Dang it, now I gotta go test all my wing's servo geometry.

 

[stangflyer]

HI TERRY! Tell me more! So far this summer I assembled the H9 Sukhoi (control horn pivot point over the hinge line, control horns drilled for approx. same height over the hinge line compensating for tapered wing/aileron, but not finely adjustable, and not able to offset for make throw), the AW Yak (pilot holes for control horn pivot point over the hinge line but not installed and adjustable for offset, 3 hole control horn for height adjustment due to tapering wings/ailerons but not finely adjustable), and this Pilot Extra which also has control horn pivot point over the hinge line and three holes for height adjustment due to the tapering wings/ailerons.

What H9 and Pilot don't give you is either 1) the control horns laterally in the correct place, or 2) and option to move them. You can mount the AW anywhere on the hard point. So with the AW you can get your leverage and your offset max throw correct. But, not your synchronization. None of the three offer perfect synchronization of servos as possible. Although, they are all probably relatively close. A bolt style control horn allows for fine adjustment and therefore perfect servo synchronization. It could be done with the style horns the three planes I mention use... but the manufacturers would have to understand it and work it out with the placement of the hardpoint.

Here's what I'm looking for in terms of leverage and side load vs pry load:

View attachment 43665 View attachment 43666 View attachment 43667 View attachment 43668

Notice too, that I have my control horns wide spread for conicals. This should be standard, too.

The most frustrating step in assembling or setting up a new plane usually is the radio system. Having a H-9 Sukhoi, I totally get your drift on what you encountered with it as well as what you're delimna is now. Personally I don't think it's possible to get the best or "perfect" setup of all three worlds as you outline. Not unless you have some programmers and some awesome features on your radio. I have been very pleased with the Hitec Aurora 9X for that very reason. I'm noticing my new MZ24 Graupner has the same capabilities. Seems we have to sacrifice something in trade off for something else. On my Sukhoi, I ended up settling for linearity on my linkages, then programmed each servo independently from one another on each surface. Once the total throw on each sister servo was acquired and locked in, then I finalized everything with the fine tuning of my transmitter. In a perfect world, I feel our control surfaces should just simply move by using "The Force"....not so much though. Guess we have to settle for second best. Lol

Personally I like your thought processes and approach on setup Joe.

Staying tuned in!

 

[Terryscustom]

HI TERRY! Tell me more!.....

I fully understand how servo geometry works. I'm not going to get into a brand war, just saying there are ARF mfg's that actually do the math for horn location in relation to the servo. However even doing that they need to leave it somewhat flexible for different setups. There are also mfg's out there that use threaded rods for horns. I've built ARF's from every mfg. sold in the USA (short of some of the small fanboy supported POS planes and also not any composite planes). Very few will "fine tune" for one specific setup because people use all kinds of different servo arm options. There are also people who choose to use 1" arms because they only fly a certain way, 1.5" on wings because it's typical, some use 1.75 on wings, and on the tail feathers anything from 1.5 to 2 is typical depending on flying style.

For this reason, many times I will CNC cut my own custom horns, especially on the ailerons, for dual servo ARF's. You can't easily change the placement, but it's easy to change the height and depth of the arm if needed (if you have options to make your own).

Like Stangflyer mentioned, this is where the servo balance feature in transmitters comes in extremely handy. I used to fly JR and switched to Spektrum after they moved away from DSMX (too heavily invested in receivers). With this feature you set your max throw and best geometry you can on the inside servo, then match the outside servo as close as possible mechanically and using servo travel adjustments. Then fine balance the outside using an amp meter and the balance feature. This is quick and easy but it does point out the mistakes with horns that are not visible without doing some math.

You will continue to find the Pilot planes are well built but they use a rubber stamp control horn and every plane of theirs I have built, flown or seen in person has the horns in the wrong location.

 

[Spats]

I always say if you want to take a nap just go watch an IMAC flight. This stuff is all good and precise but it's just like IMAC to me. I applaud the work but way over thinking it for me. I just use SWB 2" arms on everything and go. The way I throw my sticks around not sure it would change anything on my flying or batteries But nice work Joe.

 

[Terryscustom]

I always say if you want to take a nap just go watch an IMAC flight. This stuff is all good and precise but it's just like IMAC to me. I applaud the work but way over thinking it for me. I just use SWB 2" arms on everything and go. The way I throw my sticks around not sure it would change anything on my flying or batteries But nice work Joe.

I like the way you think, git-r-dun, go have fun

 

[stangflyer]

I remember about 18 years ago, I had a Goldberg Sukhoi. Powered with an O.S. Gemini 160 twin. Nylon geared servos, (cuz that's about all we had before all the new metal geared servos started becoming mainstream) The plane flew well and was lots of fun for my skill level then. Fast forward to about five years ago, I picked up another new kit. I wanted to really get wild with it. Saito 180 Four stroke... (yeah I know, a little much) metal high torque servos.... I figured this thing would be an animal. It was fun, but I kept "blowing" the tail feathers off and exploding the tail all together. I even went the extent of over "beefing" up the tail in a rebuild. No help. In fact, one time in particular, I was up doing crazy stuff. I heard a "crrrraaaack" and saw a complete stab and elevator floating to the ground. Well the plane disappeared behind the hill and I thought she was a gonner. Instinct took over and much to my surprise up above the horizon she rose. I struggled quite a bit to get her down. She just would not hold her pitch. Figured it was the loss of one stab and elevator. Well, I finally managed to get the girl turned around and lined up with the grass runway. (Wasn't even going to attempt an asphalt runway landing) Upon landing it was discovered the remaining stab and elevator were fine, but the remaining elevator servo gears stripped. No wonder I had pitch problems. I came to the conclusion, "Geometry and articulation". Course our planes are much better built and better engineering now. But the point being, just enough wrong with one little oversight and it could cost far more in the long run. I applaud those that take "SERIOUSLY" geometry on control surfaces. I am with @Terryscustom and @Spats too. Git it dooooone. I just wanna go fly. But!!! I won't shave any time in setups just to get in the air. If it ain't right? She don't fly.

 

[thurmma]

Well @Joe Hunt I don't know whether to thank you or curse you Your video has probably resolved an issue I have had trying to get the IM-14 to work on my 42% Edge that I was never able to figure out, until now. I like math, but never really dug into geometry much, mainly an algebra guy, so it took a couple of watches to fully grasp the concept and then the light went off, Holy C(*#$p! how could I have missed that!

Must go now. I have a couple of wings to work on tonight so I have to get as much work done as possible today.

 

[stangflyer]

By the way, awesome thread Joe!

 

[Terryscustom]

Git it dooooone. I just wanna go fly. But!!! I won't shave any time in setups just to get in the air. If it ain't right? She don't fly.

Absolutely, I'm not talking shaving corners as much as not taking the time to modify an ARF to get the "perfect" setup. That's why we have matching in our TX's these days to make that final perfection an electronic adjustment instead of a mechanical adjustment. There is nothing so wrong with the pilot planes that it will cause catastrophic plane failure, but it will make your servos work harder and possibly limit the throws available.