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I'm building an educational model of helicopter flight controls (cyclic, collective rigging and swashplate) losely based on the Bell 206 (because I find the mixing crank pretty cool).

I picked the Technic turntable as the heart of the model and the design started to get really large because I needed a gimbal to constrain the motion of the plate. (A bit like @jwarner's model here.)

As an exercise, I decided to make the smallest reasonably non-kludgy model I could come up with. While I'm not going to use this design for my educational helicopter flight controls model, it was interesting for me because it was the smallest, kinda working swashplate model I could come up with. As a reference, the entire gimbal frame of this model (The red frame that can move up and down) is the size of just the swashplate in my more serious WIP, which uses the Technic turntable as the heart.

Video of operation.

I'm posting here because members of EuroBricks have done phenomenal work on helicopters in the past, and I have referenced many of the models presented here previously, for my current work.

I've been meandering through with my actual model and the current state of efforts are here. No photos yet - the model is not complete. Here is a failed attempt before I decided I need a gimbal to constrain the motion of the plate.

Hope to post .io files of V1 of the model in a week or so.

mini-swashplate.jpg

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hi!

cool project and quiet good approach so far.

 

You absolutely need this parts:

BrickLink - Part 2906 : LEGO Technic Propeller 4 Blade 7 Stud Diameter with Square Ends [Technic] - BrickLink Reference Catalog

BrickLink - Part 2908 : LEGO Technic Helicopter Rotor Holder [Technic] - BrickLink Reference Catalog

BrickLink - Part 2907 : LEGO Technic Ball with Grooves [Technic] - BrickLink Reference Catalog

This will make it really more easy.

 

Appart of this, the flight command itself are challenging and the major thing to solve in your case will be to allow independant movement of the collective and cyclics parts.

Maybe can you check my two main models? @Ivan_M makes cool and clear instruction for them. 

Here:

LEGO MOC AW 169 Helicopter by Ivan_M | Rebrickable - Build with LEGO

And here:

LEGO MOC AH-77 Hunter helicopter by Ivan_M | Rebrickable - Build with LEGO

Instructions are for free ;)

For a very compact but yet functionnal solutions with both collective and cyclic i have done this a few years ago:

 

I hope this could help you 

Steph.

 

Edited by steph77

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2 hours ago, technicfanatic said:

As an exercise, I decided to make the smallest reasonably non-kludgy model I could come up with.

To make a working AND small swash plate is one of the hardest mechanical tasks imho, so great effort!

It's been rumored that the new 42145 Helicopter has new parts just for this purpose (Source Promobricks):

"The main and tail rotor can be rotated in two different speeds, the main rotor consists of 5 rotor blades. These can even be adjusted in pitch, in reality this causes the helicopter to climb or descend. On both sides of the cockpit there are control sticks, with which you can actually adjust the tilt of the main rotor, to simulate a flight to the front, back, right or left. A few new parts are said to have been designed for this purpose. The set also includes a working winch, with a hook that can be let down via a device on the outer wall. both cockpit doors and the large sliding door on the side can be opened by hand."

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9 hours ago, steph77 said:

hi!

cool project and quiet good approach so far.

Thanks!

Quote

Hi @steph77, of course I know of your cool models! :classic: When I looked at your designs (very helpful to have clear building instructions, thanks) I could not figure out how the collective worked, because it seems to me that the ball gear can not slide up and down the mast.

The control rigging (cyclic and collective sticks) and the mixing crank I have solved. I'm basing this off the Bell 206 because I find the Bell 206 mixing crank quite cool. Video. My rigging is slightly different but close enough. (https://github.com/kghose/technic-models/blob/main/helicopter-controls/archived/bell206-2022.02.17-mixer-lateral-bug.jpg) (There is a small bug in the mixing lever design which I have fixed in later iterations, and of course the swashplate is not supported properly which is the big thing I am working on.)

Thanks!

 

 

Edited by technicfanatic

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6 hours ago, Jundis said:

To make a working AND small swash plate is one of the hardest mechanical tasks imho, so great effort!

Thank you!

Quote

It's been rumored that the new 42145 Helicopter has new parts just for this purpose (Source Promobricks):

"The main and tail rotor can be rotated in two different speeds, the main rotor consists of 5 rotor blades. These can even be adjusted in pitch, in reality this causes the helicopter to climb or descend. On both sides of the cockpit there are control sticks, with which you can actually adjust the tilt of the main rotor, to simulate a flight to the front, back, right or left. A few new parts are said to have been designed for this purpose. The set also includes a working winch, with a hook that can be let down via a device on the outer wall. both cockpit doors and the large sliding door on the side can be opened by hand."

:pir-grin: I have mixed feelings hearing this. A new Helicopter set will be cool. I don't think I'll fork over >$200 for this. I'll be a little chagrinned to find new parts that elegantly do what I have been stumbling around to do in a complicated manner. OTH I wonder if the focus will be on the cyclic rather than collective (which is not that difficult, TBH. The existing helicopter rotor parts already do that).

Perhaps my thing will be done before this comes out. :pir-sweet:

In any case, my focus is in making an educational model where you can see all the moving parts and trace how the thing works. Thanks. 

Edited by technicfanatic

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I always like seeing swashplate ideas - I appreciate all the documentation you’ve put together, too! Fun to see my helicopter referenced (which borrows heavily from steph77’s). 
 

9 hours ago, technicfanatic said:

I could not figure out how the collective worked, because it seems to me that the ball gear can not slide up and down the mast.

This puzzled me too for a while, but I think a section of the rotor axle in these models has been shaved down slightly, to allow the ball gear to slide. Obviously not “kosher”, but the solution is certainly compact. 
 

17 hours ago, technicfanatic said:

I picked the Technic turntable as the heart of the model and the design started to get really large because I needed a gimbal to constrain the motion of the plate.

I’ve seen many attempted designs that started at this point, but couldn’t find a compact solution to constrain the motion. I’m excited to see what you come up with! Of course for my Land Rover C-model helicopter no turntable was available, but my clunky solution does lock the upper swashplate to the main axle, at least, while allowing up-down movement. No such luck locking it to the lower swashplate, which may also be the case with your preliminary design in the video. Still, how often does a helicopter fly upside down? 

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@Pattspatt 

17 hours ago, Pattspatt said:

I always like seeing swashplate ideas - I appreciate all the documentation you’ve put together, too! Fun to see my helicopter referenced (which borrows heavily from steph77’s). 
 

:thumbup: I'm so happy you read it and found it informative. I will add more photos of the Bell 206, which I found very useful to understand the mechanisms.

17 hours ago, Pattspatt said:

This puzzled me too for a while, but I think a section of the rotor axle in these models has been shaved down slightly, to allow the ball gear to slide. Obviously not “kosher”, but the solution is certainly compact. 
 

Important insight, thanks!

17 hours ago, Pattspatt said:

I’ve seen many attempted designs that started at this point, but couldn’t find a compact solution to constrain the motion. I’m excited to see what you come up with! Of course for my Land Rover C-model helicopter no turntable was available, but my clunky solution does lock the upper swashplate to the main axle, at least, while allowing up-down movement. No such luck locking it to the lower swashplate, which may also be the case with your preliminary design in the video. Still, how often does a helicopter fly upside down? 

Yeah, the turntable's attraction is that it takes care of the plates being in the same plane, so the tilt constraint only has to be solved once.

From my inspection of Sheepo's KA-32 (https://www.dropbox.com/s/zetqsu7nxiqdm4t/SG_Kamov_KA-32_Instructions.zip?dl=0&file_subpath=%2FKAMOV_KA32_Instructions.pdf) it looks like there is no collective here. Do I understand right? Tagging @Sheepo in case this is the right handle. Sorry if it is not.

Thanks!

 

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2 hours ago, technicfanatic said:

From my inspection of Sheepo's KA-32 (https://www.dropbox.com/s/zetqsu7nxiqdm4t/SG_Kamov_KA-32_Instructions.zip?dl=0&file_subpath=%2FKAMOV_KA32_Instructions.pdf) it looks like there is no collective here. Do I understand right? Tagging @Sheepo in case this is the right handle. Sorry if it is not.

Thanks!

 

No, I've built the mechanism of this helicopter, and it does have collective, though it might be hard to notice given how much structure is moved in order to do it. In that MOC's thread on here, @Blakbird made some great renders showing how it works, if you'd like to take a look.

 

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3 hours ago, 2GodBDGlory said:

No, I've built the mechanism of this helicopter, and it does have collective, though it might be hard to notice given how much structure is moved in order to do it. In that MOC's thread on here, @Blakbird made some great renders showing how it works, if you'd like to take a look.

 

Thank you for the pointer! Those animations are _awesome_! They make the mechanisms crystal clear. I'm awed that someone took the time to make them and then describe them.

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2 hours ago, technicfanatic said:

Thank you for the pointer! Those animations are _awesome_! They make the mechanisms crystal clear. I'm awed that someone took the time to make them and then describe them.

Yeah, they are amazing!

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Most things work fine, but the offset in rotation centers between my mixing lever and the swashplate is causing my steering links to hit their limits before I want them to. Onward ...

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@Pattspatt I have found a most marvelous solution, but the margin on this forum is too small. (You might get the Fermat reference :pir_laugh2: but, truly I've found a nice combination of parts. I'll be done debugging the design the coming week and hope to post it in a new thread here.)

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@Pattspatt still writing it all up, still have to clean up the stud.io file but here are two videos with the mechanism visible (taken before I mounted the blades, pitch links and scissor link)

Top-side view: 

Side view: 

I will make a video with the complete assembly, but you all know that part already :pir-sweet:

Here's a detail view of my pivot sleeve solution. I was inordinately gleeful to have solved the puzzle this way.

pivot-sleeve-detail.png

 

Edited by technicfanatic
Add image from github repo

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Very nice! I like seeing complex mechanisms like this one. What is the black ball part you're using in the middle of the swashplate?

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3 hours ago, technicfanatic said:

It's the LEGO Helicopter Pivot sleeve, mislabeled in the official catalog as 55889 Wheel 18 x 14 smooth

It was the product of one night of searching randomly through the catalog muttering "They have a million parts, surely one of them will work."

Nice job finding that! I'll have to pick up one of those in case I ever build a helicopter. It looks super convenient, and I wonder if it'll be used in the official helicopter rumored for this summer!

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I have the mechanical aptitude of a ... well, I don’t know, but I don’t have any (Penguin with oven mitts on?)! Pretty cool looking build, though, very impressive.  Large, but probably not very shrinkable without special purpose parts. I am looking forward to the new helicopter coming up.

i mostly just had to comment on your “inordinately gleeful” comment. It completely tickled me! Great turn of phrase.


 

 

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Very clever using those ball parts with pinhole, I have a few of them and never found a use for them until now!.

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I made a swashplate using the old helicopter rotor parts in this model, with cyclic and collective controls. The collective part works by sliding the ball over a white axle that has very little friction.

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8 hours ago, CP5670 said:

I made a swashplate using the old helicopter rotor parts in this model, with cyclic and collective controls. The collective part works by sliding the ball over a white axle that has very little friction.

That's very nice! 

On 3/13/2022 at 7:39 PM, Chmashdehjare said:

I have the mechanical aptitude of a ... well, I don’t know, but I don’t have any (Penguin with oven mitts on?)! Pretty cool looking build, though, very impressive.  Large, but probably not very shrinkable without special purpose parts. I am looking forward to the new helicopter coming up.

i mostly just had to comment on your “inordinately gleeful” comment. It completely tickled me! Great turn of phrase.

Thank you for the kind words! I'm not aiming necessarily for a small model but one where the mechanism is clearly visible. It is also based off the Bell 206, so I replicated the important bits of the mechanisms.

 

10 hours ago, SNIPE said:

Very clever using those ball parts with pinhole, I have a few of them and never found a use for them until now!.

I was delighted to see how LEGO parts fit together. I started out, just as an experiment, by caging a LEGO ball with axle hole with 3x1 liftarms and noting that fit perfectly together and made a universal joint.

On 3/12/2022 at 11:21 PM, 2GodBDGlory said:

Nice job finding that! I'll have to pick up one of those in case I ever build a helicopter. It looks super convenient, and I wonder if it'll be used in the official helicopter rumored for this summer!

I would hope they come up with a set of specialized parts, such as these from the Bell 206

Bell-206-Helicopter-Swash-Plate-Sleeve.j

7cbe36bdaea6105d2cdb690a5357ad6c.jpg

 

Edited by technicfanatic

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On 3/12/2022 at 5:24 PM, technicfanatic said:

here are two videos with the mechanism visible (taken before I mounted the blades, pitch links and scissor link)

Wow, great work! Very cool to see it all exposed like that. Still takes a while for me to wrap my mind around it! Thanks for the demonstration - looking forward to seeing more independent collective motion too, assuming you plan to add a bit more friction to the cyclic’s joysticks. 

 

On 3/12/2022 at 5:24 PM, technicfanatic said:

Here's a detail view of my pivot sleeve solution. 

Genius part usage! I wonder, though - since the ball is not mounted in exactly the same plane as the turntable but one stud higher, will that cause jerky rotation once everything else attached? I’m having trouble figuring out whether that’s a problem just from a thought experiment - I do see that your towballs are in the same plane as the ball, which makes sense.

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42 minutes ago, Pattspatt said:

Wow, great work! Very cool to see it all exposed like that. Still takes a while for me to wrap my mind around it! Thanks for the demonstration - looking forward to seeing more independent collective motion too, assuming you plan to add a bit more friction to the cyclic’s joysticks. 

Heh, trust you to home in on key issues. This is exactly right - I will add some friction pins. I believe that there is no cross-talk between the two channels because the collective moves the center of rotation of the cyclic levers the same amount as it raises the pivot sleeve (as in the Bell 206), but you are correct in that I have to demonstrate this clearly.

Quote

Genius part usage! I wonder, though - since the ball is not mounted in exactly the same plane as the turntable but one stud higher, will that cause jerky rotation once everything else attached? I’m having trouble figuring out whether that’s a problem just from a thought experiment - I do see that your towballs are in the same plane as the ball, which makes sense.

Again, perceptive point! I made the center of movement the pin holes of the top disk. I did this to simplify the attachment point of the scissor link and the pitch links whose axes have to go through the center of rotation, otherwise unwanted lateral motions are introduced into what should be pure rotations. This is the reason the cyclic control links attach to the end of a bent piece which brings the attachment (almost) to the plane of rotation (it's actually 1/2 a pin hole off, but this is swallowed by the slop in the components, and this is anyway not so critical as it is for the scissor and pitch links which have to deal with rotation of the turntable as well as tilting.)

What I missed even on this iteration is the fact that we are not done constraining the motion of the swashplate. If you look at the photo of the pivot sleeve above you will note a vertical cutout. This vertical guide is essential to prevent the swashplate from twisting, which is what happens currently.

I don't have room for such a mechanism in my model of the pivot sleeve, but I can use the mechanism used in the Bell 407/412 which is an external scissor link that constrains the stationary swashplate from twisting.

407mrh.jpg

(The scissor link in question is on the left in this photo)

 

Edited by technicfanatic

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17 minutes ago, technicfanatic said:

I believe that there is no cross-talk between the two channels because the collective moves the center of rotation of the cyclic levers the same amount as it raises the pivot sleeve (as in the Bell 206)

Agreed, very nice geometry! It’s very cool to see a faithful representation in a more accessible format.

 

22 minutes ago, technicfanatic said:

I made the center of movement the pin holes of the top disk. I did this to simplify the attachment point of the scissor link and the pitch links whose axes have to go through the center of rotation, otherwise unwanted lateral motions are introduced into what should be pure rotations. 

Makes sense - thanks for the explanation!

 

23 minutes ago, technicfanatic said:

I don't have room for such a mechanism in my model of the pivot sleeve, but I can use the mechanism used in the Bell 407/412 which is an external scissor link that constrains the stationary swashplate from twisting.

Nice, didn’t realize that a scissor link is also often used on the bottom half. The solution I used was restricting lateral movement of the links to the lower half. Cool to see two examples of the real-life solution!

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