6 ms·

Isn't the advantage of using tracks supposed to be the increased surface area for traction and weight bearing? This seems to only slightly increase the surface

Isn't the advantage of using tracks supposed to be the increased surface area for traction and weight bearing? This seems to only slightly increase the surface area. It doesn't seem that this would have enough traction advantage to make the complexity worth it.

oh_sigh 8y ago
The contact patch goes from ~ 1 sqft/tire to ~3-4 sqft/tire. That's pretty significant.
- Avshalom 8y ago
  Still if that 3-4ft^2 is in the air it's useless. This doesn't stop high centering or driving into a ditch.
  - solarkraft 8y ago
    It does help with traction, though. That's an improvement over tires. However I wonder why they accept the complexity/reliability problems I assume come with this solution instead of going with added (engageable on demand) tracks.
    - stefco_ 8y ago
      Since it's DARPA it's pretty far from being fielded, so I should think they're only worried about proof of concept at this point. But if you could modularize and ruggedize the wheels and make them easily replaceable and compatible with existing vehicles, then I could certainly imagine this being quite practical in certain situations.
- Johnny555 8y ago
  Seems like they could get most of the benefit at much less cost and complexity by going with side-by-side "dualies" If one of the tires goes flat, then there's built-in redundancy from the other ones and it could be replaced in the field if needed, but no one's going to be able to overhaul this track mechanism without a shop.
Avshalom 8y ago
I feel like, having been really introduced in the WW1 tank, that tracks were mostly about keeping motive force over a much longer distance, which is almost but not quite surface area/traction. This still fails for that purpose though.
- LoSboccacc 8y ago
  Tracks were useful to cross trenches too
mcguire 8y ago
Back of the envelope: One car weighs ~3500 lbs. If I keep 35psi of air pressure in the tires, that works out to ~100in^2 of contact patch. With four wheels, that's 25in^2 per wheel or 5in square. This looks like the tread-extended contact patch is more like 12in long times the original width, or 60in^2. That halves the weight per square inch.
- driverdan 8y ago
  > If I keep 35psi of air pressure in the tires You don't. Off road you lower the tire pressure significantly.

oh_sigh 8y ago

The contact patch goes from ~ 1 sqft/tire to ~3-4 sqft/tire. That's pretty significant.

Avshalom 8y ago
Still if that 3-4ft^2 is in the air it's useless. This doesn't stop high centering or driving into a ditch.
- solarkraft 8y ago
  It does help with traction, though. That's an improvement over tires. However I wonder why they accept the complexity/reliability problems I assume come with this solution instead of going with added (engageable on demand) tracks.
  - stefco_ 8y ago
    Since it's DARPA it's pretty far from being fielded, so I should think they're only worried about proof of concept at this point. But if you could modularize and ruggedize the wheels and make them easily replaceable and compatible with existing vehicles, then I could certainly imagine this being quite practical in certain situations.
Johnny555 8y ago
Seems like they could get most of the benefit at much less cost and complexity by going with side-by-side "dualies" If one of the tires goes flat, then there's built-in redundancy from the other ones and it could be replaced in the field if needed, but no one's going to be able to overhaul this track mechanism without a shop.

Avshalom 8y ago

I feel like, having been really introduced in the WW1 tank, that tracks were mostly about keeping motive force over a much longer distance, which is almost but not quite surface area/traction. This still fails for that purpose though.

LoSboccacc 8y ago
Tracks were useful to cross trenches too

mcguire 8y ago

Back of the envelope: One car weighs ~3500 lbs. If I keep 35psi of air pressure in the tires, that works out to ~100in^2 of contact patch. With four wheels, that's 25in^2 per wheel or 5in square. This looks like the tread-extended contact patch is more like 12in long times the original width, or 60in^2. That halves the weight per square inch.

driverdan 8y ago
> If I keep 35psi of air pressure in the tires You don't. Off road you lower the tire pressure significantly.