291–296 of 296 posts
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Can you name a single person you know of with one?
Isn't this called a helicopter? Aside from the noise, etc. issues with them, what would be the difference between a flying car and a helicopter? The need for a pilot's license to fly one?
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That's a very good question. I have an EV motor control and calibration background so lots to say here. First off, peak efficiency tends to occur at mid to high speed and mid to high torque, in other words high power. Most EVs spend very little time operating anywhere near their peak power. It may take as little as 4kW to drive down the highway at constant speed, but a motor may be capable of 100kW or much more. Effi…
>He also doesn't seem to have a dyno which makes taking data and testing a lot easier. how do you test without a dyno? and isn't it easy to set up a electrical generator tied to a high wattage variable resistor to do it?
When working on water pumps I didn't need a dyno, as the fluid provided sufficient load. It was a bit tricky to make before/after comparisons though be cause getting the exact same operating conditions (torque and speed) was not simple.
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That's a very good question. I have an EV motor control and calibration background so lots to say here. First off, peak efficiency tends to occur at mid to high speed and mid to high torque, in other words high power. Most EVs spend very little time operating anywhere near their peak power. It may take as little as 4kW to drive down the highway at constant speed, but a motor may be capable of 100kW or much more. Effi…
> Efficiency at 500 to 1000 RPM is important Why is this? Thinking out loud: can't you gear your motor so that it's most efficient at cruising speed for the vehicle? But the problem is that the car still needs to be able to accelerate from zero and some gearings will make that impossible, so having an efficient band at 500—1000 RPM gives you the best chance of being able to accelerate from 0–500 RPM?
I like to plot Torque on the X axis and losses (in watts or kW) on the Y axis. Make a series of curves at different speeds (each curve is at a constant speed). These curves intersect the Y axis at zero torque, so friction can easily be seen on the Y axis. The curves have a parabolic shape (I^2 copper loss) forming a sort of butterfly. If the wings spread out at the tips (curves separate more at high torque) there may be magnetic issues. These maps are really nice, are easy to compare, and never mention efficiency at all ;-)
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We do have flying cars.
Can you name a single person you know of with one?
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Even I retrospect I think of this 2 ways 1. Could I have made that $100 if I did it specifically for the purpose of publishing the app? (For me, the answer is always yes at that amount. I could have easily washed some cars, mowed some grass, etc. I had so much free time) 2. When it comes to business, tech, particularly the early internet boom, probably some other domains; I’m just thankful to be in the minority of th…
It's not about making the money, it's about what you spend it on. If 100$ is a significant amount you're not going to spend it on a frivolous purchase, you'll spend it on the absolute necessities. And if you do want to make a purchase purely because it makes you happy, you're going to agonize over it and feel guilty for a long while. I went on to make 20,000 euros doing freelance over the next five years while in col…
Obviously, if you're at a deficit on the necessities it will be tempting to use the extra income for those things. That's a different conversation/problem however