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HomeAircraftHelicopterMiniature Aircraft Whiplash & Fury 55 › 140 Degree SwashPlate
04-25-2013 03:26 AM  5 years agoPost 1
slickporsche

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Does MA, or any other mfg, make a 140 degree swash for 10mm shaft?

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04-25-2013 11:08 AM  5 years agoPost 2
TomC

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Gold Coast, Queensland, Australia

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MA makes a 140 conversion kit and TT makes a 140. Do a bit of searching and you'll find these.

Cheers,
TomC

Nqx,Mcpx-BL,300x,450x,500x,550x
Ion-x, 10s ,SS
TT X50E 10s, HC3-Sx

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04-25-2013 04:05 PM  5 years agoPost 3
slickporsche

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TomC
Thanks a bunch, I'll see what can be found. A good place to start.

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04-25-2013 05:02 PM  5 years agoPost 4
wjvail

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Meridian, Mississippi

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Does MA, ... make a 140 degree swash for 10mm shaft?
MA kinda does. Kinda doesn't.

They make the below conversion for the 0217 swashplate but it looks like the most recent version of the 217 swash won't work. My 0217 swash outer ring is much more complete and allows for the conversion to bolt up. I don't know how the conversion would work with the new swash pictured on MA's site. You might have to call Jeff on this one.

At $100 for the swash and $45 for the conversion, I'd have to ask is it worth it? My latest experiences with FBL heads makes me believe 120 vs 140 is a moot point. It's an argument lost in the noise of progress... To my mind 120 vs 140 was a pretty small point at the best of times but is totally lost with the insertion of gyros between you and the servos. When you also consider we are now often using servos for ECCPM that are faster than yesterdays tail servos, the notion that there may be some collective mixing with cyclic pitch seems even less likely. Issues like phasing also seem less important these days.

What are you building?... out of curiosity....

http://miniatureaircraftusa.com/021...ilter_name=0217

http://miniatureaircraftusa.com/021...ilter_name=0217

Cheers,

Bill

"Well, Nothing bad can happen now."

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04-25-2013 05:18 PM  5 years agoPost 5
TomC

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Gold Coast, Queensland, Australia

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I hear what you are saying Bill. Interesting to note that last time I talked to Curtis Youngblood he told me that he preferred 140 deg on his flybarred heli's and 120 deg on his fbl heli's.

Cheers,
TomC

Nqx,Mcpx-BL,300x,450x,500x,550x
Ion-x, 10s ,SS
TT X50E 10s, HC3-Sx

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04-27-2013 10:34 PM  5 years agoPost 6
Sewer Sleuth

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UK

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I have 140 deg swash setup on my Thunder Tigre X50. The conversion set is nice and cheap but you need the original 120 deg swash plate as well.

The Hirobo SDX swash plate has both 120 and 135 deg options built in. You just need different balls for each option.

I also have a Vibe Fifty with 140 deg swash setup.

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05-04-2013 06:24 AM  5 years agoPost 7
slickporsche

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140 Degree SwashPlate
Mostly , I wanted to experience a 140 degree swash, so I personally can decide if there is a difference, and if it is worth it. I also think ccpm is Way OVERRATED. Too much interaction for my taste, and too much messing with things to remove it. The old method of using a seperate servo for the collective, fore/aft, and left/right cyclic is still the best. With modern digital high torque servos, there is very little,if any difference, between a conventional set up, and a CCPM set up. I feel that CCPM, is a seriously flawed system.

Also I won't be using an "Electronic Bandaid (3-axisgyro)" to tune everything out. I can do that with my TX,(Airtronics SD-10G), and remove all or most of the interaction. However, if a 140 degree swash would eliminate the interaction, that would be even better. I prefer to fly my heli's,and not have electronic assistance for everything, ie.Governor,3-Axis Gyro. To me, that kind of eliminates the need for the computor TX. For instance,I have been flying fbl since way back in the late 70's with absolutly no problems, and using only a tail gyro. Quite honestly, the computor TX was the most important thing to ever happen to the RC Heli hobby. Why buy a computor radio if you are not going to use the functions it provides,Swash menu,pitch and throttle curves,plus several others.

This rant was caused by someone saying the "magic word" in a post, and of course no offense was meant From THIS post.

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05-04-2013 06:29 AM  5 years agoPost 8
slickporsche

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Sewer Sleuth
You have tried it on your birds, so does it eliminate interaction? I have also read about 135 degree being better. Anyway, whats your take on it. It would also seem that you need to reposition the bell crank or servo if you want a correct linkage to the swash.

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05-04-2013 06:49 AM  5 years agoPost 9
slickporsche

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140 Degree SwashPlate
I was planning to build a WhipLash, but may go another direction cause I want a 3-blade aerobatic head,and a crazy fast heli. Nah, my attention span is too long for a watt-copter. Gotta get a wif of that nitro everyday.

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05-04-2013 04:55 PM  5 years agoPost 10
JKos

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Redondo Beach, CA

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Slick,
Servos have gotten stronger, faster, and more accurate and radio systems are much better. Interaction on CCPM has gotten way better (way less). The servos are so fast now that the issue of lagging servos with quick stick inputs should be a nonissue. You can only move your sticks so fast and now the radio and servos can keep up.

- John

RR rules!

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05-05-2013 11:52 PM  5 years agoPost 11
Sewer Sleuth

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UK

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Like Jkos says really.

From a purely mathematical perspective, 135 deg is better than 140 deg, but if you can tell the difference in real life then you are likely to be super-human!

I'm not a good enough flyer to tell you wether or not 140 deg systems get rid of interactions, but I do have an engineering education and understand quite complex trigonometry around head design, and I can see the massive mechanical advantages of the 140/135 system over the 120 system.

This is why I like it:

On a 120 deg system, the aileron is controlled by 2 servos, and each one moves 1 distance in opposite directions at full deflection. The elevator is controlled by 3 servos - the one in the middle moves 1 distance but the other two only move half a distance to full deflection.

The potential issue with this is that the two servos which only move half as far may arrive at their final destination before the centre servo, thereby bringing in the unwanted interaction.

On a 135 deg system, all servos move 1 distance in all directions, so provided all servos are equal, equal power, equal spec, equal age etc, then they will all arrive at their destination positions at exactly the same time with all inputs - aileron, elevator and collective.

The mechanics of the 135/140 system far out-weigh the design of the 120 system, but as has been said already, a lot of these errors have been removed by modern high speed, high power servos.

It's surprising the amount of mechanical advantage that extra 15 degrees around the swash plate makes, but it can easily be grasped if you understand the shape of a sine wave and how it's created.

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05-06-2013 03:05 AM  5 years agoPost 12
slickporsche

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Jkos
Yes, in my other post I mentioned about the better servos we now have, however the problem still exists, if only a small amount. I have found that interaction is not just a level swash through its full range. There are other interaction issues that exist in addition to a level swash.

In addition, I still think I could setup two helicopters, one CCPM, and one conventional,both using modern digital servos and the same computor TX, and you would not be able to tell the difference between the two helis. The collective and the cyclic will feel the same. Quick,accurate,and good centering.

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05-06-2013 03:15 AM  5 years agoPost 13
JKos

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Redondo Beach, CA

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I still think I could setup two helicopters, one CCPM, and one conventional,both using modern digital servos and the same computor TX, and you would not be able to tell the difference between the two helis.
Then I'm not sure what you're questioning.

If you can make both fly the same, then I would take the one with fewer parts any day.

- John

RR rules!

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05-06-2013 04:54 PM  5 years agoPost 14
wjvail

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Meridian, Mississippi

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Like Jkos says really.
From a purely mathematical perspective, 135 deg is better than 140 deg, but if you can tell the difference in real life then you are likely to be super-human!
I'm not a good enough flyer to tell you wether or not 140 deg systems get rid of interactions, but I do have an engineering education and understand quite complex trigonometry around head design, and I can see the massive mechanical advantages of the 140/135 system over the 120 system.
This is why I like it:
On a 120 deg system, the aileron is controlled by 2 servos, and each one moves 1 distance in opposite directions at full deflection. The elevator is controlled by 3 servos - the one in the middle moves 1 distance but the other two only move half a distance to full deflection.
The potential issue with this is that the two servos which only move half as far may arrive at their final destination before the centre servo, thereby bringing in the unwanted interaction.
On a 135 deg system, all servos move 1 distance in all directions, so provided all servos are equal, equal power, equal spec, equal age etc, then they will all arrive at their destination positions at exactly the same time with all inputs - aileron, elevator and collective.
The mechanics of the 135/140 system far out-weigh the design of the 120 system, but as has been said already, a lot of these errors have been removed by modern high speed, high power servos.
It's surprising the amount of mechanical advantage that extra 15 degrees around the swash plate makes, but it can easily be grasped if you understand the shape of a sine wave and how it's created.
Alright... I got bored this morning and thought I'd dig out some old math. Get ready. Geek alert. See sketch...

As I've said in the past, I really don't think there was ever much reason to run a 120 vs 140 swash. The "interaction" being discussed is only ever a consideration if the servos are moving at full speed and that interaction is only a factor in collective pitch for the moment it takes the two lagging servos to catch up. This typically would require using massive pitch (elevator) cyclic commands. The most obvious maneuver where you might see this is in tic-tocks. Here you are potentially going from full nose down pitch to full nose up pitch in rapid succession. Even in this extreme example, you might only see a small bump in collective pitch and only then while in transition. Remember that you're doing tic-tocks so you're already likely giving large collective inputs. Would you feel this bump?

There is a noticeable mechanical advantage to 140 ECCPM over 120 but several things bring the value of this into doubt. First by using ECCPM we are already ganging the torque and speed of three servos to do the work of one (as you would see in MCCPM). On a 120 ECCPM setup, the front servos have 1/2 the lever arm and therefore 1/2 the mechanical advantage, but(!), there are two servos in front doing the same work as the one rear servo. How much torque and speed do you need and at what point is more unnoticeable? The second point is that 1/2 of the mechanical advantage comes not from the fact that the balls are spaced differently (120 vs 140 or 135 deg), but from the fact that the balls are typically much longer. In the little sketch I did, you have to go from 5mm balls to over 11mm balls to achieve the goals of 140 ECCPM. Notice in the attached photos that not only have they changed the spacing of the balls around the swash, but the balls are over 100% longer (or include extensions to achieve the same effect).

Yea... I was bored. Standing by to have my math corrected. I will confess I think there is an error in my calculation of the 11mm ball length* but I'm going flying!

Cheers,

Bill

* (33mm/cos(40)-28mm = 15mm

"Well, Nothing bad can happen now."

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05-06-2013 09:31 PM  5 years agoPost 15
Sewer Sleuth

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UK

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The way I see it......

On a 120 deg system, the centre of the three balls are position equally around a circle concentric with the main shaft. This means that the elevator ball is say 1 unit away from the mainshaft, and the corresponding collective and aileron balls are 0.5 units away on the other side - hence on the elevator control, the two side-by-side servos move half as far as the pure elevator servo, no matter how much stick is applied. On the aileron control, the two side-by-side servos move equally and opposite, but only 0.87 as far as the elevator at full deflection. Hence why many helis flip faster than they roll.

On a 135 deg system, the concentric circle idea is thrown out of the window, and the balls are position so that they are all 1 unit away from the mainshaft in both of the perpendicular directions. Hence, all cyclic inputs are equal in all directions. The result is that the heli flips at the same speed as it rolls (well, in theory anyway), and there is never any servo lag in any direction because all servo travels are equal on all controls. The downside of the 135 deg system is (as you've said already) the two side-by-side balls are further out from the mainshaft to achieve this.

I've tried to demonstrate this in the attached picture, starting with a 120 deg setup, and then converting the same swashplate to 135 deg setup to show how it makes the swashplate bigger overall.

https://rc.runryder.com/gallery/92383/Sawshplates.jpg

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05-06-2013 09:34 PM  5 years agoPost 16
JKos

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Redondo Beach, CA

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> Hence why many helis flip faster than they roll.

I don't think so. The amount of swash tilt and thus cyclic input is dialed in to be the same for aileron and elevator inputs. Thus, this isn't the cause.

- John

RR rules!

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05-07-2013 12:01 AM  5 years agoPost 17
Sewer Sleuth

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Yes, you're right John. I was waffling jibberish at that point....

Of course the software in the Tx will compensate for the reduced aileron mechanical throw in the same way that it compensates for the two side-by-side servos on the elevator control.

But the point remains that there is no compensation in the 135 deg system in any axis - it's a mechanically purer system.

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05-11-2013 01:32 AM  5 years agoPost 18
slickporsche

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140 Degree SwashPlate
Jkos what my point was is that the mccpm works better,especially with modern servos, and no need to worry about interaction. Yes, there would be more parts. I also have aileron to elevator interaction and the opposite also. Could be the programing in the radio. To me its a pain in the ass to mess with, when I can use mccpm and not mess with anything. Of course there are not many helis these days with Mccpm.

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12-17-2013 02:19 AM  4 years agoPost 19
Sam2b

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Tacoma, WA

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139.1066054 degrees
I know, 7 months later... It's a geek-off. Here's a cool sketch I think the guy named "CAM" (with quote marks) made that calculates closer to 139.1066054 degrees if using a straight linkage ball stand off from the swash. Likely splitting hairs, so I guess people just say 140, but I'm sure the computers that cut the metal make it 139.1066054 degrees.

Older thread with this sketch: https://rc.runryder.com/t498965p2/

_Sam B_

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