Verifying Mitsubishi advertising
Message Body:
“Hi Robert. I’m thinking you are probably the best qualified person to investigate the implied claim made by Mitsubishi in this YouTube advert. It seems improbable that a stock ute – or any consumer 4wd for that matter – can do 45 degree climb. Please could you investigate? Thanks.”
Sure. Yes that’s real. End of investigation.
Okay the limiting factors for a steep gradient are:
– torque
– traction
– centre of gravity
Any 4×4 with low range can deliver enough torque to climb vertically. So that’s no problem.
Traction is where things start to become limits. Mitsubishi are using a high-traction surface, and the car’s weight is equally distributed across both rear wheels. Even so, the car is approaching its limit of traction.
Centre of gravity play a part here. If the CoG is too high then the car will tip back and not be able to climb at all. For such a climb you want a very low, forwards CoG so as to bring the front wheels into play as much as possible. This then ties into my point about EVs with motors front and rear – in that climb, the front wheels aren’t doing a whole lot of helping, but because the front and rear axles are connected all the motor’s torque can be delivered to the rear wheels if needs be. With front and rear disconnected motors the front motors might have one bazillion newton metres but if there’s no traction, well it isn’t going to help.
So just about any 4×4 could do this. It’s like the pull-an-airliner stunt, looks spectacular but in reality not very impressive. The actually impressive features of engineering aren’t very marketing-friendly.
In Australia you tend not to find 45 degree angles because the traction just isn’t there. Not only is the surface not a nice metal ramp, the vehicle’s wheels aren’t level. In the USA that’s a bit different as they have a lot of very high-traction slick rock.
Humans are pretty terrible judges of angles. The steepest urban road is around 6 degrees. A really steep driveway might be 15-18 degrees. In the bush, a 20 degree climb would be seen as a serious hill, and 25-30 really steep. Sand can only slope to around 32 degrees as it is loose, more on the downwind side.
Now comment away saying your favourite track is actually 60 degrees and you only bother considering a winch if it’s 70 or more….and don’t get confused with degrees, % and ratios.
