My New Cyclic Build with Magnetic Brake Trim - ED Forums
 


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Old 05-27-2017, 11:24 AM   #1
molevitch
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Default My Mi-24 New Cyclic Build with Magnetic Brake Trim

I have been running a 2xMSFFB2 modded cyclic for a number of years. I fly DCS helicopters almost exclusively now, especially the Huey, Mi8 and Gazelle. My current stick has a long extension with a CH fighter Stick Grip with some additional buttons and an extra hat switch from Warthog spares.

I find the deadzone in the MSFFB rig increasingly frustrating when flying the helicopters using refined and necessarily miniscule motor skills. The "twitchiness" of the Gazelle is frustrating with such a deadzone exaggerated by the stick extension.

I have been interested in the idea of incorporating an authentic cyclic (and collective) into my rig for some years, but the real things from surplus MOD stock are often prohibitively expensive, or just plain trashed. So imagine my surprise when I acquired a Lynx cyclic recently on ebay for £180.00. Similar items are generally listed at £250 plus.

So now I have the core for a new cyclic build project. A real cyclic, with a heavy steel tubing stick and cast metal grip is too heavy for any standard retail joystick gimbals.

Time to get real!

I am not an engineer, and I do not have access to CNC machinery. (Well I do, but its a 1 hour drive away....). But I have a good set of tools, and a reasonable skill set. Plus I am a designer of things.... I wanted to be able to achieve good and effective results without resorting to complex machinery, to keep it simple but efficient, and to use as many readymade components as possible.

Design. After many hours of internet searches, I referenced these other projects, and credit them as my guides and inspiration.

http://1stcavdiv.conceptbb.com/t2568...ith-force-trim
https://www.youtube.com/watch?v=5DvmLN-ryP4

I set about ordering components.

For my gimbal, I settled on a combination of aluminium box section pieces, pillow block bearings and steel rods. All ordered from eBay. 35mm box tubing would be cut to a 100mm length and filed to fit over the base of the cyclic tubing at the pivot point, and to give it some flat surfaces to mount other connections. At 35mm external, this will fit inside the 50mm x 100mm x 100mm external box giving a clearance for rivets used to secure pillow blocks on the outside of the ext box. See images.

3x Steering dampers ordered from China via ebay. 1 to be saved for upgrade to existing collective system, 2 for the cyclic project. Springs ordered from RS components. The dampers end attachments were removed after heating with a blow torch for a few seconds to soften the glue used to secure them. The 50mm long compression screws were then threaded onto the rods at each end and the stops and connectors reattached. These will be the force gradients for attachment to the gimbal.

3 x fire-door electro-magnets ordered from China via ebay. These will be the magnetic brakes for the force gradients. running from a 12v transformer, they will be disengaged by a PTB button added to the cyclic grip as the Trim button. The steel blocks which are acted on by the electro-magnets will be mounted on short bearing sliders, for drawers, also bought on ebay for a few pennies....

With all components on site, it took a morning to put it all together. I learned one extra valuable lesson. DON'T buy cheap HSS drills....

The biggest and probably most time consuming part of the project is probably going to be working out how to connect up all the switches from the wiring loom. Luckily all cables are named and numbered and grouped, but all disappear into a 55pin mil circular connector.
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Last edited by molevitch; 07-20-2017 at 06:08 PM. Reason: update
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Old 05-28-2017, 05:08 PM   #2
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Thats a nice pit coming up.
Could you keep it updated how the project takes shape.
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Old 05-28-2017, 07:39 PM   #3
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Of course I will as it comes along. I am away this week but will continue building on my return
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Old 05-29-2017, 03:04 AM   #4
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Mole that is a really nice simple design. I might draw some inspiration from your build myself to try to mod my microhelis cyclic base. I've got a serious space limitation in my motion pit, so I'm not at all sure what I'm going to do at this point. My dual FFB2 is what I'm now using because it's fairly compact in terms of footprint and doesn't extend below the floor like my sweet microhelis base plus it gives me Force Trim, but if you say the dead zone was bothering you it will probably bother me too.

I'm not home right now, but I'm thinking I might be able to make this work for me if I can solve a problem or two and make it fit.

The one problem I see is there is going to be no friction/resistance whatsoever when the Force Trim is off. I'm going to ask Comanchero about the feel of the stick with Force Trim off.
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Old 05-29-2017, 10:40 AM   #5
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Hi Trip, thanks for the kind words. The design is not strictly mine, though the gimbal kind of is. I just needed simple solutions as I don't (yet) have a good tool-shop setup.

On reflection, I am thinking to turn the mechanism around, and put the pitch force gradient under my seat, rather than extending into the area where my feet are. That way, the entire mechanism will be an extension of the seating support. I have a sports-car seat which is adjustable and on sliding rails which I got off eBay some years ago for £40.00, and it has space under it so....

Alternatively, for ease of maintenance, I may put it all in a box/under a floor. That way, it will all be accessible for tweaking and tightening up, without needing a full breakdown. I am building pedals to go with it all, and incorporate into the same control system. The interface will be Leo Bodnar board(s) based. And the pitch, roll and yaw will all be read by Hall sensors, not pots.

I will be adding cast rubber boots to the cyclic, pedals and collective, once I get there....

Anybody with any advice about interpreting the wiring from the Lynx grip switches would be gratefully received. There are groups of cables, numbered. But each switch has 4 cables.... I think I worked out the 4 way hat switch. A simple test circuit I can make with battery and light bulb, contacts etc, but that 55 pin plug is damn fiddly to connect to! And finding a mate for it is either REALLY expensive, or really random. Found one, but it will need filing to fit.
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Old 05-29-2017, 10:53 AM   #6
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Nice work I look forward to your success and will enjoy the build along the way, thanks for sharing
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Old 05-30-2017, 02:16 AM   #7
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I'm just going to cut the round pin connector off my collective and wire it up as with any other type of switches. I don't know what to tell you about four wires per switch though, that is weird!
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Old 05-30-2017, 09:28 AM   #8
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Those might be double-pole switches. Either for redundancy (so it still works if one connection breaks) or it might switch both a higher voltage signal to do the work and a lower voltage signal to notify some flight computer about the switch state.

Either way, you can take a multimeter, find two wires that are disconnected when the switch is off and become connected when the switch is on, and ignore the other wires

Disclaimer: I have no knowledge at all about real-world avionics. I am just a computer scientist who tinkers with electronics in his free time.
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Old 05-30-2017, 10:47 AM   #9
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Quote:
Originally Posted by molevitch View Post

Anybody with any advice about interpreting the wiring from the Lynx grip switches would be gratefully received. There are groups of cables, numbered. But each switch has 4 cables.... I think I worked out the 4 way hat switch. A simple test circuit I can make with battery and light bulb, contacts etc, but that 55 pin plug is damn fiddly to connect to! And finding a mate for it is either REALLY expensive, or really random. Found one, but it will need filing to fit.
A long time ago in a galaxy far,... well you know the rest of it, I have terminated those connectors, and all I can say they were interesting to say the least. If I can suggest a budget digital multimeter (not too budget) might be more useful for you.

I'm not sure on your skill set but an option might be to terminate the wiring loom onto a db 37 and maybe a db 25 connector if you want to retain the ability to easily disconnect it. But as someone else has suggested the dual contacts maybe a failsafe arrangement.

I've gotta say your gimbal looks great I'm currently thinking about doing my own torque pedals so keen to see any developments.
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Old 05-30-2017, 01:48 PM   #10
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Quote:
Originally Posted by FragBum View Post
A long time ago in a galaxy far,... well you know the rest of it, I have terminated those connectors, and all I can say they were interesting to say the least. If I can suggest a budget digital multimeter (not too budget) might be more useful for you.

I'm not sure on your skill set but an option might be to terminate the wiring loom onto a db 37 and maybe a db 25 connector if you want to retain the ability to easily disconnect it. But as someone else has suggested the dual contacts maybe a failsafe arrangement.

I've gotta say your gimbal looks great I'm currently thinking about doing my own torque pedals so keen to see any developments.
Thanks Fragbum! I may take the soft option and cut the plugs off. Sadly.... there is the 55 pin and also a 10 pin, though the 10 is only host to 4 cables. I think I will cut and terminate in a long connector bar for ease of management. Easier to test as well.
I will post some sketches illustrating the pedal design and the overall design later.
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