[Work not in progress] Flight Simulator

[mocbuild101]

So, it's already been three days since the contest was announced, and I still haven't built anything yet... It's probably time to get started then! 

 

The Inspiration:

The idea for my entry comes from the main model of set 8485 - a set I'm still yet to build despite owning most of the parts...

 

The Goal:

My plan for this build is basically a modern version of the above model, but with a plane replacing the helicopter, and including the following features:

• Movable ailerons and elevators
• Lifting, rolling, and pitching of the plane
• Full manual control - no remote control. (hopefully)
• Possibly something else...

 

The First Prototype:

Rather than spending an extra day building a working prototype, I decided to just quickly build the basic idea in LDD, as I know from experience that I rarely end up using anything from the first prototype...

 

Anyway, that's all for now, I hope to have something functional built either tomorrow or the next day...

Edited December 23, 2018 by mocbuild101

[mocbuild101]

Small update...

I've been working on the control system a bit, and I think I've finally gotten something suitable for the main joint:

The thing that took the most time to figure out was how to build it joints without using up too much space, as I had to replace the CV joints with U joints, because the maximum angle of the CV joints was too small for what I wanted.

My next task is to find a way to hold and move the main joint with a joystick...

[mocbuild101]

Update...

I've been experimenting with different ways of manualy controlling the plane, and well, it's hasn't been very successful - even the best design I could come up with (below) still had so much backlash that the control surfaces barely even moved...

I looks like I will have to go back to the drawing board, and find a different way of controlling it... (probably involving PF) 

[Rudivdk]

I believe that linkages are the best way to control airplane surfaces, as they have little backlash and you can span large distances with them. No idea how that would help your build though, running multiple linkages through the joint would be a challenge,  and because your plane will move on a single point, it would move the endpoints of a linkage even when not intended... Would it fit somehow if you used these to transfer the movement in the central joint? From all gears they have the least backlash... guess it will explode the size of your joint... Maybe PF would be the only way to go. 

[KikoTube]

1 hour ago, mocbuild101 said:

control surfaces barely even moved..

And that is the main problem with builds like this. Now think about it, with some weight on the control surfaces. It wont even turn a little bit.

As @Rudivdk said, the best would be to go with a full linkage system.

Edited December 8, 2018 by KikoTube

[mocbuild101]

1 hour ago, Rudivdk said:

and because your plane will move on a single point, it would move the endpoints of a linkage even when not intended...

That's the reason why I ended up with the design I have at the moment, as I had to make sure the axle rotation wasn't on either of the two planes of the joint's rotation (which is also why I couldn't add yaw).

I do have an idea of a way to use more linkages though - only keeping the two U-joints and the CV-joints. I think I might have a play around with some ideas in LDD tonight and see what I can come up with...

[Rudivdk]

11 minutes ago, mocbuild101 said:

I do have an idea of a way to use more linkages though - only keeping the two U-joints and the CV-joints. I think I might have a play around with some ideas in LDD tonight and see what I can come up with...

Cool, always have a Plan B

Good luck with that, hope it works out for you!

Edit: just a wild thought... could pneumatics work? Tubes can run through the joint without issue, the cilinders can handle lots of weight without backlash, and with a compressor and airtank in the base structure you always have enough pressure...

Might not be what you're looking for, but I thought I'd share the idea.

Edited December 8, 2018 by Rudivdk

[Jeroen Ottens]

You can reduce the impact of slack by adding a big gear reduction near your control surfaces. If you add wormgears for instance near your controlsurfaces you will need to turn the gears on your stand many rotations, but you will be able to control the surfaces very well and even a few degrees of slack in the drivetrain will only result in a very limited slack in the controlsurface. Of course it does mean that you can't use a joystick-like controller on your stand.

[mocbuild101]

15 hours ago, Rudivdk said:

Cool, always have a Plan B

Or just make up Plan B when you need it... 

15 hours ago, Rudivdk said:

Edit: just a wild thought... could pneumatics work? Tubes can run through the joint without issue, the cilinders can handle lots of weight without backlash, and with a compressor and airtank in the base structure you always have enough pressure...

Hmm... That actually might be perfect for moving the joint itself, as I haven't really been able to find a good (or strong) enough solution for that yet, and I also want it to be able to move smoothly...

 

Anyway, this is what I came up with last night, I haven't yet had a chance to test it IRL (I'll be doing that later today), but I think I could work...

Also, I found out something about LDD that I never knew it could do - move linkages with the rotate tool! 

Spoiler

 

[Rudivdk]

Looks good with the linkages. I think this would already be a big improvement over your previous version in terms of responsiveness. Nice compact solution for the ailerons btw. 

[mocbuild101]

17 hours ago, Rudivdk said:

Looks good with the linkages. I think this would already be a big improvement over your previous version in terms of responsiveness. Nice compact solution for the ailerons btw. 

Thanks, I've done some testing, and it's working great - so well in fact, that I think I'll won't need any PF! 

BTW, I probably won't be posting any pictures until tomorrow, as I want to build more of the control system before posting any updates...

[Cylo]

This is looking great! I'm following with interest.

[m00se]

Looks great. Reminds me a bit of this:

 

(Lego Technic ideas book 8891 from 1991)

[Erik Leppen]

This looks like an interesting project. The hard part indeed is making sure the movements of the control surfaces match the movement of the plane itself. At the same time I think you don't want the position of the joint too far outside the body of the airplane. Ideally the joint is near the center of gravity of the plane...

So maybe you cna also follow the approach taken in that Idea book model @m00se mentions to control the plane angles, and then link the plane's control surfaces to the motion of the central block within the plane.

Anyhow, looking forward to more of this. I think it can become a very fun model.

[mocbuild101]

20 hours ago, Reaper said:

This is looking great! I'm following with interest.

Thanks!

11 hours ago, m00se said:

Reminds me a bit of this:

Oh yeah, I forgot about that one!

8 hours ago, Erik Leppen said:

At the same time I think you don't want the position of the joint too far outside the body of the airplane. Ideally the joint is near the center of gravity of the plane...

Agreed, though I don't know whether I can get it any closer with the current design...

 

Anyway, I'm currently working on a new design for the joystick that eliminates even more backlash, by not using any U-joints.

I still don't have any photos to show just yet, but the design seems to be working well, so I hope to have something later today. 

[m00se]

12 hours ago, Erik Leppen said:

At the same time I think you don't want the position of the joint too far outside the body of the airplane. Ideally the joint is near the center of gravity of the plane...

I'm building something similar for the contest, and that is exactly what I had totally wrong. If the joints are to far out you'll need way more torque than a universal joint can handle.

[mocbuild101]

Update! (finally...)

I took a break from this for a couple of days to build a set I bought, but I'm back now, and I had a idea of how to build the lifting mechanism.

I actually built it in LDD yesterday, but I ended up not having the time to post it here...

Here's what the colored parts are:

• Red = The plane.
• Green/Yellow = Controls.
• Blue = Base structure (non-moving).

I haven't yet tested it IRL (which is what I'll be doing today), but I think it should work...

[allanp]

Looking good. I wonder if all the backlash can be removed but andding just a tiny amount of pre-tensioning via some rubber bands at each end to keep the linkages just slightly in tension or compression. Not enough to stress the linkage, just enough to emilinate the backlash.

[mocbuild101]

I've decided to abandon this build for now, as I really haven't made any progress the past week, and I think it's best for me to leave it.

I will most likely come back to this at some point, as I still think it can work, but it won't be for TC15 unfortunately...

 

BTW, I'm not yet dropping out of the contest, as I have some other ideas, and I still have over a month to build something. 

[m00se]

That's a pity, I was really looking forward to your model given we were both doing something similar. Good luck with your next idea.