Showroom 6DOF Stewart AC Servo Motion Helicopter Build

Those were NEMA17 stepper motors and TB6600 drivers. They are cheap but a bit too weak. Spending a few $ more for NEMA23 motors and MD542 drives would be much better. And it wouldn't even use more space because the fans could be omitted.

I think NEMA23 motors with gearboxes would be lighter. The torque spec of the Rhino stick is ~9Nm with a 6.25 gear ratio (timing belt). So the NEMA23 motors have around 1.5Nm.

Yes, its all in the gearing. But theorectically they should not get hot enough to need fans.

Can't get near my sim, too many chores to do. Maybe tomorrow....

depends on what helis you fly, if you want the trim release and autopilot stuff its nice

Ah yes, it's that senario where if you haven't got the bits in place to make it work, you just have another non functional button.

I've created a repository at Github, and stuck all the part and assembly files, for anyone that wants to flame me , or is curious enough to want a look.

And being the cheapskate that I am, it's all done on FreeCAD. I added all the files, which means if you stick them all in FreeCAD you can turn all the individual parts on/off depending on what you're looking at.
I've also added some contrasting colours, and transparency to make it easier to distinguish parts.

https://github.com/TheGettinBetter/6DOF_Sim
I've added the motors for the cyclic FFB, and made a ton of un-noticeable changes. But hey, I'm having fun.

Probably not the final edit (in fact almost certainly not) but its all about evolution.

i am by no means a programmer but with these

having ffb could you program one to mimic the other?

Maybe, I'm not too sure.

I have already ordered FFB motors from VPforce, and they have acknowledged payment, I went for larger motors to negate the use of fans, plus to use those in the video, would mean I'd have four motors (2 for each one).

By making the cyclic sticks mechanically connected, instills positional confidence and lowers the need for extra motors.

I have changed the title to include 'Helicopter', as the possibility of making it dual purpose (i.e. Driving & Flying Sim), is beginning to take a back seat. The helo components are becoming more dedicated and I am thinking I may just stick to my original concept (i.e. a helicopter).

No, mechanical link is the only real way. It's been discussed many times on vpf discord

The center position and spring force comes from the game. Then, the pilot pushes to a new position. What would the copilot stick do? Does it switch to the new center of the pilot's stick? with what force? How would it tell 'who is the pilot'? What if the copilot is an instructor? would them pushing the stick be felt by the student? Its all a crazy feedback loop.

you have the X motor on the tube? probably better to floor mount it and bolt on separate balance weights to tha back of the tube if needed. Also you will need some hard adjustable end-stops.

I did initially mount it on the floor, but then when you put in some forward cyclic, it adds sideways cyclic as the shaft rotates. Putting it on the shaft stops this.

When I actually make it, the intension is to have it all balanced around the centre point, with the FFB taking care of self centering.

Agree about the hard stops, but will factor those in later, when I'm happier with the basic design.

I think it should be possible. Of course, the connection can't be totally stiff, otherwise it would cause oscillations. But you could model a spring that adds a force proportional to the position difference to both sticks. So it's like a stiff spring or a bit flexible connection rods. Each pilot feels what the other does and there's no need to detect 'who is the pilot'. You'd probably also need damping.

But I agree that this solution doubles the number of motors required and therefore the price. So a mechanical connection is much simpler.

I bet you wouldnt even notice, with that long of a rod between motor and its connection point. I certainly dont and mine is much shorter

I agree, you probably wouldn't notice, but I know its there, so my OCD means I have to design it out...
BTW, thats a very nice system you have there, and very tidy. Nice work

Getting close now, motors (at least some of them) will be here by Friday, pulleys are also enroute.
Added the collective, any comments appreciated. Notice I put all the weight on the passengers side.
Zip is on Github here





As before, all files in one folder, open Bell206_Cockpit_Assembly-4.FCStd
Tip: Parts can be turned on & off by selecting them in the tree view, and hitting the space bar.

Right, we're on the move. Bashed a few bits out.

Managed to get the base board done, plus the first two sheet bits. Had to make the bender first.

Here's the bender, all made from scrap lying around.

Ordered a load of plugs and stuff, to connect motors, plus another two motors from VPForce for collective and pedals.

Had a good productive day today, and retired to the PC. Whilst printing some more dwgs and adding dims to others, I started to think about the max weight the system would be able to handle.

So I knocked up this spreadsheet, would you agree? Have any comments.
All base helo parts are 2mm ali, mid sections and roof are going to 0.5 Ali
FFB motors are 11kgs, and two people I would say roughly ~200kgs,
so IMO its getting close to the limits....

Hmm, I think unless you and your co-pilot are very skinny 200kg gross weight is not enough. I'd plan for at least 160kg for two people and 100kg for the empty rig. AFAIKS, your torque calculations are correct. In the calculations for my own rig I assumed that the maximum force needed for a single actuator is about twice the static force when the rig is balanced and centered. That would be 2.55kN / 6 * 2 = 850N.

But that's an extreme case when the position of the rig is at maximum roll/pitch and/or surge/sway which normally won't last very long. And you can overload the motors by a factor of 2 or 2.5 for several seconds before they quit.

However, the static force is not weight/6 but a bit higher depending on the inclination angle of the actuators which is not streight vertical. At ~30° (lowest position) it's 490N per actuator and at 20° (estimated middle position) it's 450N. So that's well below the 597N. What's the efficiency of the gearboxes?

Interesting comments, but I was actually allowing 200kgs just for the two pilots, + ~11kgs for the motors.
If my max is 365kgs, I have to get the chassis at least under 100kgs. I'll weigh all the bits as I manufacture....
OMG I haven't included the seats or the touch screens, Bass shaker..... good job its all aluminium.

The gearbox efficiency is listed as 95% so max available comes down to 346kgs.

I can't see me over loading by a factor of 2.5, and much of the time there will only be one person in it, and I'm pretty sure helos don't require too many sudden movements.

I'll have to create MAX WEIGH labels, or upgrade motors

BTW: Shoutout to @smitty for the great advice to ditch Virpil and go with VPforce, it was a great idea, and am so glad he nudged me into looking at their products again. Not that there's anything wrong with Virpil, but the FFB is the next level, and I know full well that I'll want it later, so might as well fit it now.

Another option would be to change the gear ratio to 1:60 or 1:70. 3000RPM/70 is still 0.7RPS or 257°/s. So it takes less than 0.3s to move the full -45 to +45° stroke. So Even 1:100 would still be sufficient for super high enough speed.

No need for bass shakers... If you have good servos they can generate vibrations and rumble from the infrasound well into the audible bass frequency spectrum. 100Hz is no problem. I've tested PeterW's rig and you can feel every single flap of the rotor blades.