[TC12] Fire Ant - One-minute pitch

[Didumos69]

From the beginning of this project I assumed that keeping the center of gravity of the mid-section below the turn table rotation centers, would give this car straight line stability. Now I probably won't succeed in that, so I figured I will probably have to add a kind of return-to center with silicon bands to keep it straight. Not too tight though, steering should still be easy. But since a few days I started to doubt this whole line of thinking. Suppose the center of gravity of the mid-section lies below the turn table rotation centers. In that case gravity will add to straight line stability, no dougbt about that. But when making turns, the centrifugal force will compensate for the gravitational force or even overcompensate. In the latter case the driver will have a hard time when pulling the steering wheel straight again after a turn. The car wants to keep on turning or even turn sharper, until speed (and thus centrifugal force) drops of course.

I reckon a mid-section with a center of gravity at the same level as the turn table rotation centers seems the most wise thing to do. And probably a return-to-center mechanism for straight line stability. Any other thoughts on this forces matter?

Edited September 16, 2017 by Didumos69

[Lipko]

Just focus on the model, and this is "wacky races", not "sound and paradigm-shifting concepts race".

If you let the center of gravity move away from the turning-circle's center (and slightly elevate), you actually make the vehicle more instable (prone to flip over) when cornering compared to a fixed center of gravity (just imagine the center of gravity at an extremely low position). In real tilting vehicles the cabin tilting is forced and the center of gravity is moved inwards, so the cornering will be more stable.

[Didumos69]

9 minutes ago, LvdH said:

What about something like this? This was sometimes used for return to center steering when we didn't have a servo yet.

http://www.brickshelf.com/cgi-bin/gallery.cgi?f=468841

Thanks! I know those options. I will first build it in real life and then see whether I need a return-to-center.

9 minutes ago, Lipko said:

Just focus on the model, and this is "wacky races", not "sound and paradigm-shifting concepts race".

I wouldn't want to claim any game-changing concepts in this build. The design is finished and I was just trying to imagine how a real car like this would behave, what driving it would feel like. It just boggled my mind.

12 minutes ago, Lipko said:

In real tilting vehicles the cabin tilting is forced and the center of gravity is moved inwards, so the cornering will be more stable.

That makes sense, thanks!

[schraubedrin]

6 hours ago, Didumos69 said:

Any other thoughts on this forces matter?

The dynamic stability of this suspension is an interesting question.

Here a simple sketch depicting the centre of gravity and steering axles:

My thoughts on cornering: here, two forces are interacting:
- the centrifugal force, pulling the centre of mass outward, increasing the steering force
- gravity, pulling the centre of mass downward and decreasing the steering force.
This setup depends on the grip of the tires and the centre of gravity.

I'm not so sure with the high speed stability, my brain just locks up thinking about the whole axle turning

 

[Didumos69]

On 9/16/2017 at 7:02 PM, schraubedrin said:

- the centrifugal force, pulling the centre of mass outward, increasing the steering force
- gravity, pulling the centre of mass downward and decreasing the steering force.

That was what I was thinking too. I guess, given that the center of gravity of the mid-segment is higher than the turn table centers, I will need a centering feature to obtain straight line stability. If I do need such a feature, I will first try this simple solution: A perpendicular pin axle connector attached to the steering axis with a silicon band running through its pinhole. The ends of the silicon band are wrapped around a bush sticking out of the back of the bottom frame. That should help keeping the steering wheel centered. The max angle of the steering wheel will be around 45 degrees.

 

Edited September 17, 2017 by Didumos69

[Didumos69]

While awaiting parts, I did some work on the engine. It now encloses the gear so the rear side looks a little less messy. It brought the engine one stud more to the back and a little higher. I'm not sure whether I actually like it better, but perhaps it's because I got used to the previous setup too much. What do you think, which is better (click to enlarge)?

EDIT: Removed images, I opted for the new engine layout.

Edited September 21, 2017 by Didumos69

[Didumos69]

On 19-9-2017 at 10:37 PM, Didumos69 said:

I'm not sure whether I actually like it better, but perhaps it's because I got used to the previous setup too much.

I'm happy with it now, so I will keep the new engine layout.

I started building. Actually, it's almost done. Only the seat and the tires need to be added, but I don't have the parts yet. I had to make a few small changes to the design to make it buildable, but nothing with much impact. And it works! It works like a charm !

I did not install the return-to-center which I had in mind, because I concluded it would be better to have a straight line stabilizer which operates directly on one of the axles and not on the steering axis. So I added a 'hidden' straight line stabilizer. I leave it up to you to find out how it works .

Here are the first real life images and a short video:

Edited September 21, 2017 by Didumos69

[Ivan_M]

It is nice but I was expecting better steering radius, I think the back of the car might move more.

[Didumos69]

Just now, Ivan_M said:

It is nice but I was expecting better steering radius, I think the back of the car might move more.

Due to the missing tires the bottom side of the mid-section sits very close to the ground, which limits the tilting angle. With the tires attached I expect more angle.

[Ivan_M]

Oh I didn't realize that it hit the ground, it is fine then

[Didumos69]

Just now, Ivan_M said:

Oh I didn't realize that it hit the ground, it is fine then

Another consideration I made: Giving the back of the car more steering angle would boil down to giving the mid-segment less tilting angle for the same steering radius, while tilting is the whole point of this build. Also, I deliberately wanted the back to steer less than the front to avoid the tail from breaking out too much like you see with wheel loaders.

[Isamudyson]

It looks even better physically built compared with the renders

[Nebulaire]

Can't wait to see it on tyres !

Can you share you LDD file ? I want to building your go kart !

[Meatman]

The physical model looks really cool. I thought that it would have a much tighter steering radius as well.

[Andy D]

3 hours ago, Nebulaire said:

Can't wait to see it on tyres !

Can you share you LDD file ? I want to building your go kart !

@Didumos69 I'll second that! I am much looking forward to the completed model. I would like to build this as well! This is the coolest thing I have seen this year. I know your entry will do well its [TC12].

Thanks,

Andy D

[Didumos69]

7 hours ago, Isamudyson said:

It looks even better physically built compared with the renders

Thanks!

4 hours ago, Meatman said:

The physical model looks really cool. I thought that it would have a much tighter steering radius as well.

Thanks! It has a tighter steering radius than shown in the video. A few days and then I'll show you the finished model.

7 hours ago, Nebulaire said:

Can't wait to see it on tyres !

Can you share you LDD file ? I want to building your go kart !

3 hours ago, Andy D said:

@Didumos69 I'll second that! I am much looking forward to the completed model. I would like to build this as well! This is the coolest thing I have seen this year. I know your entry will do well its [TC12].

Thank you guys, great to know people are eager to build this. @Nebulaire, I hope you can wait a few more days. Building from the LDD-file will proof hard. There is practically only a single 'legal' building path and it will be hard to find it without any hints. Once I received the latest parts - I expect them this weekend - it will be a matter of days before I will finish BI by means of a photo sequence. I could share a parts list in advance if you wish?

Edited September 21, 2017 by Didumos69

[Nebulaire]

7 hours ago, Didumos69 said:

 @Nebulaire, I hope you can wait a few more days. Building from the LDD-file will proof hard. There is practically only a single 'legal' building path and it will be hard to find it without any hints. Once I received the latest parts - I expect them this weekend - it will be a matter of days before I will finish BI by means of a photo sequence. I could share a parts list in advance if you wish?
 

Of course I can wait. Take your time, i'm not in a hurry

I'm ok for the partlist, thanks

[mocbuild101]

Looks great in real-life (just as I expected), but I still can't get over the fact that it just looks like a ordinary car...

[Didumos69]

On 15-9-2017 at 3:46 PM, Thirdwigg said:

Thanks for giving it a try. Still a great design.

@Thirdwigg, your remark on 'width' was still in the back of my mind and my earlier attempts to do something with it failed. Problem was that I tried to put something over the rear wheels, which didn't blend with the rest of the car. But now that I started building I wasn't particularly happy with the stomp 'nose' of the car either. So I gave it another try and I think I'm onto something that does the car justice and also addresses your point:

Edited September 22, 2017 by Didumos69

[Didumos69]

2 hours ago, mocbuild101 said:

Looks great in real-life (just as I expected), but I still can't get over the fact that it just looks like a ordinary car...

You better get over that if you don't want to miss a wacky experience .

[Thirdwigg]

@Didumos69 I'm happy I had an effect on the project.

The panels on the rear looks good. If you are interested, one of the initial thoughts I had was to replace the upper 3l axles on each side of the upper #2 connector on the back of the motor with 4l axles, with a red axle connector on each side, with a 4l bar in Trans red inserted into the axle connector. This may give it a little more width, while retaining the light and airy look.

Regarding the front, the two panels look overshadowed by the "nose" and look a little squeezed by the tires. Can you mount them in front of the wheels at the same height? Maybe replace the two 1x3 liftarms with 3x3 L liftarms and mount the panels on a longer axle to move them more forward and out.

I appreciate your collaborative design process, and the resulting design is better because of it.

[Didumos69]

14 hours ago, Thirdwigg said:

@Didumos69 I'm happy I had an effect on the project.

The panels on the rear looks good. If you are interested, one of the initial thoughts I had was to replace the upper 3l axles on each side of the upper #2 connector on the back of the motor with 4l axles, with a red axle connector on each side, with a 4l bar in Trans red inserted into the axle connector. This may give it a little more width, while retaining the light and airy look.

Regarding the front, the two panels look overshadowed by the "nose" and look a little squeezed by the tires. Can you mount them in front of the wheels at the same height? Maybe replace the two 1x3 liftarms with 3x3 L liftarms and mount the panels on a longer axle to move them more forward and out.

I appreciate your collaborative design process, and the resulting design is better because of it.

Thank you very much @Thirdwigg! Your suggestion for the front is brilliant! Amazing that I didn't think of this myself. Somehow I'm very reluctant in having a nose that surpasses the front wheels, but I'm certainly going to do this. Your initial idea with the trans red bars for the back is also nice, but for now I think I will hold on to a rear spoiler. I think a rear spoiler gives a nice balance with a nose-spoiler.

As for the collaborative process. Especially when it comes to looks, I can usually use some advice to get to something that is perceived well by a wider audience.

[Didumos69]

On 22-9-2017 at 9:32 PM, Thirdwigg said:

Regarding the front, the two panels look overshadowed by the "nose" and look a little squeezed by the tires. Can you mount them in front of the wheels at the same height? Maybe replace the two 1x3 liftarms with 3x3 L liftarms and mount the panels on a longer axle to move them more forward and out.

On 23-9-2017 at 12:45 PM, Didumos69 said:

Thank you very much @Thirdwigg! Your suggestion for the front is brilliant! Amazing that I didn't think of this myself. Somehow I'm very reluctant in having a nose that surpasses the front wheels, but I'm certainly going to do this.

So this is what I did with it. I'm very happy with the effect!

I also reverted the straight line stabilizer to the original idea; a red silicon band through a perpendicular connector attached to the steering axis. The stabilizer I had was applied to the rear segment. As a result tilting was partly absorbed by torsional flex in the mid-segment, causing the rear segment to steer less than intended. This modification also paved the road for the use of an 11x5 frame in the bottom of the mid-segment, which made the mid-segment much more stiff.

Finally, here's a video giving a better impression of the steering radius. This is still not the final result, because the final tires have slightly bigger diameter than these old wheels.

Edited September 24, 2017 by Didumos69

[Isamudyson]

Wow with that new front it now looks like a ramp you can just plow through opponents. It also looks small/ simple enough to even be a actual technic set kids would enjoy

[Thirdwigg]

That looks great. I'm happy it worked so well.