[Finished] Fox 8x8 V2

[Zerobricks]

I think it's time to update and rebuild the legend..

Differences between the old and the new model:

• Because the model will be powered by 3x BuWizz instead of 4 AA battery boxes, it will be at least a kilogam lighter.
• Independent suspension will be changed to a live axle suspended pendular type. This will allow for much more movement when going offroad and more even weight distribution on the axles.
• Gear ratio will be changed from 1:3 to 1:1,677 due to the increased power of the motors, decreased weight and improved suspension - making the model 80% faster.
• NO MORE U JOINTS. Since no U joint, or CV can withstand the torque of an XL motor powered by BuWizz, the motors are now directly mounted on the hubs and steer with the wheels.
• Because there are no U joints the axle can be narrower by 4 studs, but I had to sacrifice a stud of ground clearance comapared to the old one.
• Servo steering - steering is now updated with 2 servo motors, each in their own axle. Front-most axle's steering angle is 25 degrees. Rear axles no longer need steering due to...
• Differential steering - since all motors can be individually controlled, the BuWizz's app allows for automatic correction of motor speeds when steering. This means the model can steer even tighter by reducing the speed of the inner motors when steering.
• Improved wheel mounting points using parts 24122 - the torque is now sent directly to the inside of the wheels without having to use 24 tooth gears and pins.

 

I ordered the missing components and will send photos of the build as it progresses.

For the bodywork I am thinking about a red cabine, but not sure which style - high and flat, or low which stick out in front further.

Additional functions will be a winch in the front and possibly a crane arm in the back - I will decide on that after I see how it performs.

Edited March 3, 2020 by Zerobricks

[suffocation]

This is going to be awesome!

4 hours ago, Zerobricks said:

[snip] no U joint, or CV can withstand the torque of an XL motor powered by BuWizz [snip]

Based on your experience, do you think two BuWizz-powered, hard-coupled XLs geared UP 3:1, going into a diff (20:28) and from there to two of the new CV joints/planetary hubs are likely to cause damage? It's for a 4.5 kg vehicle, hence no extreme off-roading, just driving around the house.

[Zerobricks]

14 minutes ago, suffocation said:

This is going to be awesome!

Based on your experience, do you think two BuWizz-powered, hard-coupled XLs geared UP 3:1, going into a diff (20:28) and from there to two of the new CV joints/planetary hubs are likely to cause damage? It's for a 4.5 kg vehicle, hence no extreme off-roading, just driving around the house.

I think the issue with that setup will be gear that will be geared up 3x. If it will be an 8 tooth gear, it will suffer. I dont think anything else would be an issue.

[suffocation]

Thank you!

I was thinking more 36:12 In any case, gears are cheap and plentiful - it's the new CV joints and planetary hubs that are still rare and overpriced.

 

[KirTech LAB]

Can't wait for the result!

[Gray Gear]

What kind of tires are these? First I thought you were using the Exo Force wheels because of the color, but those would be bigger I believe. To me it looks like stacked BMW tires, but on what wheels will you fit them? The Porsche's? That would be so cool, a Offroad monster with sportscar wheels 

[Saberwing40k]

51 minutes ago, Gray Gear said:

What kind of tires are these? First I thought you were using the Exo Force wheels because of the color, but those would be bigger I believe. To me it looks like stacked BMW tires, but on what wheels will you fit them? The Porsche's? That would be so cool, a Offroad monster with sportscar wheels 

Those tire are actually just an LDD stand in for these ones:

These are from set 8675, and apparently have very good grip.

[steph77]

Hello,

Big model...

Won't you experience powersupply issue ? 8 XL motors is quiet a lot for one BB.

And if you have differents sources, how can manage the eventual difference of power of the different sources (=different speeds at Wheel in final)?

[Zerobricks]

1 hour ago, steph77 said:

Hello,

Big model...

Won't you experience powersupply issue ? 8 XL motors is quiet a lot for one BB.

And if you have differents sources, how can manage the eventual difference of power of the different sources (=different speeds at Wheel in final)?

 

17 hours ago, Zerobricks said:

 

• Because the model will be powered by 3x BuWizz instead of 4 AA battery boxes, it will be at least a kilogam lighter.
• Differential steering - since all motors can be individually controlled, the BuWizz's app allows for automatic correction of motor speeds when steering. This means the model can steer even tighter by reducing the speed of the inner motors when steering.

 

 

[steph77]

Oups. I mises that. Sort.

This automatic speed correction is a great stuff. Then!

Thx

[Gray Gear]

4 hours ago, Saberwing40k said:

Those tire are actually just an LDD stand in for these ones:

These are from set 8675, and apparently have very good grip.

A friend of mine when I was like 8 years old had this RC Car featuring these Tires, and I got to try it out. Was pretty amazing, the Tires were pretty soft, and the Car pretty fast, we had so much fun. Good memories 

[Zerobricks]

While I'm waiting for the missing parts, I started building the front axles. Here's a few photos from the build process:

Each hub uses double gears, it's the only way they can survive the gear-breaking torque from an XL motor powered by BuWizz. The pendular suspension allows up to 5 studs of height difference between axles and each axle can tilt some 15-20 degrees sideways.

[Zerobricks]

I received the missing parts and finished the chassis:

As you can see the suspension is very flexible, so the weight is spread evenly over the 8 wheels:

And here is an amazing climb over couch's vertical step of over 20 cm height:

I need to reinforce the chassis and make the cab next, but so far, so good!

[Gray Gear]

1 hour ago, Zerobricks said:

I received the missing parts and finished the chassis:

As you can see the suspension is very flexible, so the weight is spread evenly over the 8 wheels:

And here is an amazing climb over couch's vertical step of over 20 cm height:

I need to reinforce the chassis and make the cab next, but so far, so good!

Wow, thats amazing!

Keep the weight down, thats some amazing power right there 

[Ox1337]

Fantastic!

Are these wheels compatible with regular axles? AFAIK no, so how have you mounted them?

Thanks

[Saberwing40k]

On 9/8/2019 at 5:07 AM, Zerobricks said:

 

The wheels are mounted on the black pieces shown in this picture.

[Attika]

That couch climb is otherwordly.  Oversized caterpillar on nitro! Nice. I had an unreal thought: What if you hinge the chassis behind the first- and at the front of  the 4. axle, and spring load them.  So when it reaches the "couch corner", the front of the chassis with the front axle does tilt up for an extent, somewhat guiding the rest of the chassis. Like a real caterpillar.  It is only possible if no drivetrain goes through the chassis, and you have that lucky case. 

On a second look its not that obvious due to the tandem-like setup.

 

Edited September 27, 2019 by Attika

[Gray Gear]

21 minutes ago, Attika said:

That couch climb is otherwordly.  Oversized caterpillar on nitro! Nice. I had an unreal thought: What if you hinge the chassis behind the first- and at the front of  the 4. axle, and spring load them.  So when it reaches the "couch corner", the front of the chassis with the front axle does tilt up for an extent, somewhat guiding the rest of the chassis. Like a real caterpillar.  It is only possible if no drivetrain goes through the chassis, and you have that lucky case. 

On a second look its not that obvious due to the tandem-like setup.

 

YES! this is a great Idea, it would increase climbing potential by a lot!

Or you could make it two sections with 4 wheels each, connected to one full length frame, that can pivot forwards and backwards as well, kind of like the Suspension used on some older Tanks  (M4 Sherman had this I believe)

Edited September 27, 2019 by Gray Gear

[efferman]

On 9/26/2019 at 9:41 AM, Zerobricks said:

20 cm height

Those tires must have an insanely grip.

[MajklSpajkl]

That climbing ability is really amazing! How heavy is it so far?

[Zerobricks]

5 hours ago, Attika said:

That couch climb is otherwordly.  Oversized caterpillar on nitro! Nice. I had an unreal thought: What if you hinge the chassis behind the first- and at the front of  the 4. axle, and spring load them.  So when it reaches the "couch corner", the front of the chassis with the front axle does tilt up for an extent, somewhat guiding the rest of the chassis. Like a real caterpillar.  It is only possible if no drivetrain goes through the chassis, and you have that lucky case. 

On a second look its not that obvious due to the tandem-like setup.

 

Spring loading sounds like an interesting idea, but would cause issues, the second and third axle could touch when going against the obstacle. A pendular chassis might be a better idea. 

 

29 minutes ago, MajklSpajkl said:

That climbing ability is really amazing! How heavy is it so far?

Around 3 kilograms, planning to make a simple body, to keep performance high. 

[Attika]

16 minutes ago, Zerobricks said:

Spring loading sounds like an interesting idea, but would cause issues, the second and third axle could touch when going against the obstacle. A pendular chassis might be a better idea. 

Definitely. At the first quick look I thought it has 4 separately linked axles. The gif has dragged my attention before I had a good look on the structure.  

Edited September 27, 2019 by Attika

[Zerobricks]

I found the time to finish this monster. For the styling I was inspired by the set 6989:

This is what the finished model looks like:

The rounded cab gives the model a fuuristic look and can easily fit a whinch, three larger seats and one of the three BuWizz bricks:

A couple of large large 3:4:5 triangles supports in the back keep the chassis from bending too much when the rear axles push up against the front:

And of course the obligatory couch testing photo where you can see the range of suspension movement:

Video coming soon!

 

 

Edited March 3, 2020 by Zerobricks

[ginger-snapped]

Awesome build! Definitely nailed the futuristic vibe with the oval cabin. Can't wait to see that suspension in action!

[Gray Gear]

I dont really like the oval shaped cabin, but thats just my taste. But it should help this beast to climb really steep slopes, with all the weight in front  it won't tip over. I am waiting for some impressive offroading 

Edited March 4, 2020 by Gray Gear