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by the way, how does it have enough grip to tow the hummer?
You do not need a lot of grip to pull a hummer. This cars are around 3 tons.
The breaks were not engaged so we may assume the wheels were rolling freely
So the robot would have to pull with a force of 3000kg*10(m/sē)*0.015=450N
It would need around 450N/10(m/sē)/0.8= 56.25kg. Thats a bit low, because it is calculated without resistance inside the car (gear box etc.)
Since this thing was build out of solid metal, I guess it is not a light weight.
As you may have realised they are pulling a similar stunded in the video with the touareg.
So if I am going to steal their calculations you get up to 132 kg for the bot. Well, the truth shall be in this intervall.
I do not feel like digging up technical datas today.
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Yeah, but if the hummer is 4700 lbs, and say you put on 320 lbs of gear on the drone and still only use a fraction of the energy needed to tow a hummer.
Now for 320 lbs you should be able to get a Mk 19 automatic grenade launcher, camera and turret mechanisms, and 144 grenades. Not a bad bit of hurt done by a robot. Swap out the grenade launcher for a .50 cal and have some fun.
True on a flat road, not so true for other surfaces.
Lets say sand. We do not even consider the secondary factors like sinking in. We are looking at the sand as it would be as solid as road.
Instead of my numbers for the hummer I will go with yours (around 2100 kg for the hummer). And I will make I wild guess for the Robot based on the numbers of the VW to be at the save side. This would mean the robot would have needed around: 93 kg. Lets assume he is around 150, it seems ok.
So to pull the hummer on the road he would need a force of:
(150*0.015+2100*0.015)*10 = 370 N (Since I left out any resistance from the vehicle itself, lets take 720N)
Now lets go with 150 kg of gear in the dessert.
Well, to pull this:
(150+150)*0.3*10= 900N
This seems somehow extrem. On the other hand: Try to ride your bike at the beach.
I am open for any corrections in my calcualtion. I just made this up on the fly. So I am not sure if I missed anything. Just applyed basic physics.
But it seems right. Sand/road is about 20-40 times the force needed.