- First Name
- A. J.
- Dec 8, 2019
- Reaction score
- Tesla X LR+, Lexus SUV, Toyota SR5, Toyota Landcruiser
- EE (Retired)
Let's try to take some of the guesses out. Sixty mph is 26.82 m/s. If the CT accelerates uniformly from 0 to 60 in 2.9 seconds that 26.82/2.9 = 9.25 m/s/s (0.94g). Now we have to guess at the weight. Using 5500 lbs that means mass of 2500 kg. The power required to accelerate 2500 kg at 0.94g from 60 mph is P = m*v*a = 2500*26.82*9.25 =620212 joules/sec (watts). One horsepower is 735.5 watts. Dividing by that gives 843 horsepower. Now that's the power required to accelerate the mass. At 60 mph there is, of course, substantial drag and also rolling resistance, drive train and slip loss to overcome so the motors will have to deliver somewhat more than 843 hp. So now we are back to some guesswork. Assuming the frontal area to be 4 m^2, Cd = 0.4 and air density to be 1.225 kg/m^2 the drag power load would be 1.225*26.82^3*0.4*4/2 = 18906 Watts equivalent to another 25.7 hp. Drag would be the major load after the inertial one and so allocating 32 hp to all of them is probably reasonable. This brings the estimate to 843 + 32 = 875 hp distributed over the three motors. If equally apportioned that would be 292 hp each.Pretty simple to say all these numbers people are giving out on Horsepower of the CT are educated guesses.
This estimate is based on what it would take to meet the stated 0 - 60 requirement which is, I assume, the most stringent power requirement placed on the motors. The big assumption underlying it is that the motors' power limited regions start at 60 mph (given the huge significance attached to 0 - 60 times in the automotive industry). I don't think that's an unreasonable assumption and I'll stand by 875 or so until I hear differently from someone like Sandy Munroe. All the other numbers are, as the quote says, either guesses or marketing hype.