Comments by "geemy" (@geemy9675) on "Engineering Explained"
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.36 sounds hard to achieve with a standard trailer..I think the rear is as important as the front and I found: "Generally, CD values for a semi-trailer truck are ranges from 0.5 to 0.9 depending on the aerodynamic design of the truck." base line is actually 0.8 and 0.5 is achieved only with side fairings hiding all the wheels area and trailer flush with the tractor.
otherwise, numbers are not too far off. its still probably going to have slightly less range than they announced, a bit less payload, more expensive charging (thanks "inflation/wars...").
average maintenance cost should be way better though, as long as the battery's good. but having your truck immobilized for weeks or months because of back ordered part, etc...is not good for businesses. Tesla needs to be on a whole other level regarding repair times, or provide replacement semi during those repairs at least under warranty.
Anyway, it makes way more sense to use batteries for delivery vehicles that travel less miles, at slower speeds, and spend a lot of time accelerating, braking, stopping, idling...they also don't have the same penalty that heavier means less payload, they come in all sorts of sizes and weight so if the truck's 20% heavier, it's not such a big deal. tesla should definitely consider making delivery vans or even people transportation. they don't need megacharger network they'll just charge overnight and will run all day long on a charge
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clever design, but also shows how much simpler is a 4 motor electric powertrain. only 4 moving part, the rotors/half axles, no driveshaft, no differential/LSD, no clutch. wheels can turn at any speed and apply traction control and torque independently. you can do off road, software locked differentials, drift mode, torque vectoring, stability controls, FWD/RWD bias, more precisely and without using the brakes. only downside is you can only apply the power of one motor to any wheel, but thats not really an issue save maybe for extreme drifting where you would want 100% of your peak power directed to the rear
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so if you're driving on cruise control at 80mph on the highway, wheel rpm is about 1000rpm, so the shaft is about 4000 rpm so the clutch will slip at around 4000*0.7%~30rpm and at low load, but it doesn't make sense that the clutch doesn't completely disengage, to reduce wear and fuel consumption? obviously mileage os not concern #1 on a corolla GR, but reliability under heavy use?
I understand it's not going to heat up or wear as fast as a clutch launching the car at 3000+ rpm but still a very odd design to have a clutch slipping 100% of the time. plus a manual transmission only has a big speed difference when starting from a dead stop, when changing gear, speed difference is either minimal (perfect shift) or the clutch slips and the engine speed matches the gearbox after a few tenths of a second. the clutch spends less than 0.7% of the time slipping from a stop to first gear, and it has thermal mass to take the heat, and then cool down when its not used, whereas this will lose power and generate heat continuously. If you hammer a clutch several time in short intervals its going to overheat for sure.
my concern is not only that there's a clutch slipping all the time, but that its also responsible for continuously transferring ~50% of the torque to the rear wheels so not.
Of course if it makes the AWD/handling better, the part is easily serviceable, then OK why not! people who are lucky enough to put their hands on this car wont mind low mpg
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some mentioned the delay that is visible between in the initial footage where the car is stopped and both the steering wheel and the wheel are visible. is it noticeable/annoying when driving? Also you failed to mention variable gear ratio steering has been implemented and abandoned by both Honda (Honda S2000 VGS) and Toyota (Land Cruiser VGRS) in the 2000s ... it would be interesting to see a comparison, to see if they improved the technology, or if it's just making a comeback because it makes more sense in EV's with large screens, yokes, and self driving around the corner. Personally I think it makes sense because:
1 it allows the driver to have a more consistent range of motion at low and high speeds
2 forcing the driver to do 3 full rotations of the steering wheel for three point turns is not great if you can have power steering that allows you to do it without taking your hands off the steering wheel
3 having less sensitive/slower steering at high speeds can be a good thing
but they are concerns though, like
1 the learning curve, is it more dangerous when you're not used to it or someone borrows your car? it could be fixed with settings though
2 how to handle switching frequently between cars with fixed and variable steering.
3 how is muscle memory affected for emergencies, like quick steering adjustments to avoid a car that tries to merge into you, or oversteer/loss of traction
4 how it feels in a long corner with a radius that tightens or widens, to have the ratio change as your speed increases or decreases, and have the steering change with a constant steering wheel input....
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