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  1. Fumesucker

    throttle for RC motor

    You need what is known as a "servo tester", there are several brands available, the Astro Flight seems to be the most popular. You will have to do a bit of soldering to change the potentiometer in the tester over to the twist throttle. Here is a link to a servo tester/wattmeter combination...
  2. Fumesucker

    "Open source" motor?

    It's really quite a logical idea, I can see two problems though. The first is that magnets on the rim are going to pick up ferrous debris from the road. The second problem is that the coils really need to be around the entire circumference of the rim to fully utilize the magnetic field of the...
  3. Fumesucker

    "Open source" motor?

    Good point, that's why I'm asking for input, to identify where the losses are and decide how to minimize them. After reading about variable torque in an axial flux motor via changing the air gap I think that it might be a better to forgo driving the pedals and drive the wheel directly through a...
  4. Fumesucker

    "Open source" motor?

    One interesting point regarding axial flux motors is that you can vary the torque characteristics of the motor fairly easily by manipulating the air gap, narrow gap gives high torque, low rpm while a wider gap gives less torque but higher rpm. A mechanism to allow the air gap to be changed...
  5. Fumesucker

    "Open source" motor?

    I used to be quite good with motors back in the days when electric RC planes were really just getting started, built a several two stage gearboxes, one with two motors, in order to get the highest power to weight ratio. Did quite a bit of rewinding and other motor mods for increased power and...
  6. Fumesucker

    "Open source" motor?

    OK, I'll start off with a couple of ideas I have. Rectangular magnets rather than round ones would be preferable I think, it would be possible to get a more even magnetic field that way with magnets just touching each other around the periphery of the armature. Trapezoidal shape magnets would...
  7. Fumesucker

    "Open source" motor?

    I was very interested in this post by axbor22 about the axial flux friction drive motor he built: http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=6762 A low rpm/high torque, high efficiency motor capable of driving the chainring with only a single gear, belt or chain reduction...
  8. Fumesucker

    Mounting your battery, Center of Gravity.

    Interesting, I hadn't thought of that. I think you are correct.
  9. Fumesucker

    Mounting your battery, Center of Gravity.

    Eh, we all have our blind spots. It's interesting that it's not what we don't know that is most dangerous to us but rather what we do know that isn't so. Thanks for an enjoyable chat, I often solidify my own understanding of things when I try to explain them to others. Your observations make...
  10. Fumesucker

    Mounting your battery, Center of Gravity.

    I'll assume, for the sake of argument, that you are correct. How then do you initiate a turn on a bike? If the lean all happens from the tire contact patch, then there is no mechanism other than shifting your weight to effect a change of attitude on the bike. Try riding no hands and then try...
  11. Fumesucker

    Mounting your battery, Center of Gravity.

    Consider a bike whose CG is just 1" above ground level, any time you try to change direction, you have to move the entire weight of the bike to one side or the other, that is going to require considerable effort that has to come from somewhere. It's generally easier to rotate a weight about an...
  12. Fumesucker

    I made my bike Jelous

    Your post is the prime reason I'm probably *not* going for some kind of lithium cells. At the moment I'm trying to decide between nimh and nicd. And your post also reminded me of the very last of Murphy's laws: Mother nature is a bitch. Too bad about your battery.
  13. Fumesucker

    Mounting your battery, Center of Gravity.

    I'm defining a "flick" as going from lean angle in one direction to lean angle in the other direction quickly, as you would for a series of "S" curves at speed. Are you aware of what "countersteering" is? Countersteering is how we actually steer bicycles and motorcycles, except a lot of us...
  14. Fumesucker

    Mounting your battery, Center of Gravity.

    I'm "Old Skool" and don't climb all over the bike during vigorous cornering so my body weight is mostly at least part of the "flick". It seems to me that you want your major weight (batteries) located somewhere relatively close to the longitudinal line around which you rotate the bike to assume...
  15. Fumesucker

    Using RC motors on E-bikes [Archive]

    If hall sensors aren't fast enough, you could always use optical, I've done enough with optical stuff to have no doubt they are plenty fast for controlling a motor.
  16. Fumesucker

    Using RC motors on E-bikes [Archive]

    Since Castle Creations has a low cost line of low voltage controllers out (Thunderbird) I find it hard to believe that it is the "sensorless" part which is driving up the costs. Assuming of course that the CC low voltage controller does as good a job as their more expensive versions. After all...
  17. Fumesucker

    Mounting your battery, Center of Gravity.

    Given that was what I said, then yes, I do get that. :) A low polar moment of inertia means that the mass is centered tightly around the longitudinal axis. My wording was not perfect (I used the word "low" when I probably should have said "small"). I have a hard time sorting out your replies...
  18. Fumesucker

    charlie rose ,lutz and the chevy volt 8-21-08

    On another site I read that Lutz basically complained that educated people on the coasts would not or did not buy their cars. I know I've been avoiding American cars for a long time after some notably crappy ones in the early 90's.
  19. Fumesucker

    Using RC motors on E-bikes [Archive]

    Yes, a "Headwind" option could prove useful. And I agree that the lower the KV, the easier the gearing becomes.
  20. Fumesucker

    Using RC motors on E-bikes [Archive]

    A "Watt hrs/mile" and "Watt hrs/km" readout would be nice. Very informative piece of work, I've enjoyed playing with it. On edit: A "Human Input" option would be nice too.
  21. Fumesucker

    Mounting your battery, Center of Gravity.

    I love you too, safe. :D So a bike with a very high CG is easy to flick and is hard to ride at low speeds? Trials riders get as low as they can on the bike for balance at low speeds? Obviously for good flickability you need the polar moment of inertia around the longitudinal axis to be as...
  22. Fumesucker

    Using RC motors on E-bikes [Archive]

    Good catch, you're right, I misread something apparently. Note the "Performance by KPH" and "Resistance breakdown" sections. 26/39 is 0.666
  23. Fumesucker

    Using RC motors on E-bikes [Archive]

    I checked and the ratios for a ten percent grade were so close to 5:1 and 3.3:1 that in the real world it would make no difference.
  24. Fumesucker

    Using RC motors on E-bikes [Archive]

    After much more head scratching I think I may have a handle on the multiple vs single motor gearing difference. If you go from a single motor to a dual of the same power you should double your power, so all you have to do is use the e-bike spreadsheet someone kindly sent me to calculate the...
  25. Fumesucker

    Using RC motors on E-bikes [Archive]

    You can use a very simple mechanism to dyno motors. Use something like a propeller to absorb the torque, which as Jeremy pointed out you can measure with a spring scale. RPM is no problem to measure these days. Your "propeller" doesn't have to actually develop thrust, I made a whole series of...
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