ES DIY Motor Challenge

[Miles]

How about 10nm/kg continuous and 20nm/kg peak? I found something that might help level the playing field a bit, since it has juicy formulae along with a triple rotor/double stator layout in a hub motor layout with real world efficiency of 93% and 97% highway. http://www.itee.uq.edu.au/~aupec/aupec03/papers/114%20Greaves%20full%20paper.pdf

Interesting find, John. It's on a completely different scale, though....

I think the 4 Nm/kg target is a more reasonable goal, for us.....

[Miles]

That's good for a few laughs. Good thing I don't need to spend so much time explaining things to him anymore.

Maybe someone could casually mention transverse flux motors on the MotoredBikes forum....?

[Miles]

I think the 4 Nm/kg target is a more reasonable goal, for us.....

To give an example:

A 1 kg motor running at 2400rpm would be able to output 1 kW continuously....

[John in CR]

How about 10nm/kg continuous and 20nm/kg peak? I found something that might help level the playing field a bit, since it has juicy formulae along with a triple rotor/double stator layout in a hub motor layout with real world efficiency of 93% and 97% highway. http://www.itee.uq.edu.au/~aupec/aupec03/papers/114%20Greaves%20full%20paper.pdf

Interesting find, John. It's on a completely different scale, though....

I think the 4 Nm/kg target is a more reasonable goal, for us.....

I didn't mean to suggest a change in goal. There just seemed to be a lot of meat in that paper that might eliminate some of the guesswork. Now that you have me trying to think in terms of torque machine instead of motor, it's especially interesting that Greaves talks about only torque in that paper. LFP is going to see that 250nm continuous 500nm peak and want to put it on his bike as is. I can see him now riding around on what is essentially a lipo battery with wheels and one of these monsters inside the back wheel.

[AussieJester]

I can see him now riding around on what is essential a lipo battery with wheels and one of these monsters inside the back wheel.

LOL @ Lipo battery with wheels, pretty good description of Lukes bike there Miles

[Miles]

LOL @ Lipo battery with wheels, pretty good description of Lukes bike there Miles

Yes, but it was John's, Kim...

[Miles]

In case anyone needs it, the formula for rotary power is:

Power (Watts) = Torque (Nm) x Angular Velocity (radians per sec)

Angular Velocity = 2pi * 60 * rpm

So:
Watts = Nm * rpm * 2pi / 60 , or
Watts = Nm * rpm * 0.105

Solved for torque:
Nm = Watts * 60 / rpm / 2pi , or
Nm = 9.549 * Watts / rpm.

[enoob]

lol. im in if you gents are willing to let my ghetto entry in . id like to see a formula that takes into account $ spent and time in for total power out . that said i have no idea how much time ive put into this and dont really worry about that part.

Otherwise consider this a THROW DOWN.

Barring any problems i have found most of the things i need to get this done . the magnets get here in the mornin (shipping weight of 1.7 pounds) and i intend to put around 1-2 pounds of copper in it still. no steel , fibreglass structure for the windings.





ill have shots of the rotor in the mornin. just working on dressing it up a bit . may get lighter as im waffling on some things but i figure i can always get the drill out again and put more speed holes in the case if i need to make a weight requirement. lol

[recumpence]

This is so cool!

I am an absolute Moron when it comes to understanding motors. But, I can sit back and watch with pleasure.

I am good at implementing someone else's motor onto a bike. It is cool to see people actually start from scratch and make their own working motor.

Come on, Gents, lets see some DIY horsepower!

Matt

[Thud]

Enoob, you are in the lead.
I have been looking at weight reduction all day to better atack the parameters Miles laid out. I am curious how the alternator conversions compair to the other motor options.
on a side note I worked on my eddy brake dyno last night. I overheated the magnet rotor & the epoxy flowed. Fail! interesting gizmo though.( I am thinking a simpler friction brake will have to suffice)
E, how are you going to test you motor?

[enoob]

overheated the magnet rotor & the epoxy flowed. interesting gizmo ( I am thinking a simpler friction brake will have to suffice)

sounds like fun to me . i woulda had a blast with ya .

E, how are you going to test your motor?

lol now this is funny . im making 2 and sending one to you to test.

no really . check this out


im sure you recognize the paper glued to the rotor blank there. horrible failure that one. after a few attempts at getting what i wanted out of my wood working gear i retreated and i am picking up the first version (done on an endmill) in the morning right after i drop the boys at school.

im getting enough magnets to make at least 3 of these . so im lookin at you if your willing to find and old alternator to take a rotor and stator ill send ya. may only make one halbach a conventional nsnsns with 20 magnets is the backup.

[etard]

Awe Cmon Matt, you aren't gonna let the other guys have all the fun here! Are you?

So what are the parameters here in case one were to imagine that they could build something like this? Does it have to at least be within certain weight restraints, and spin at least within a usable rpm, with maybe universal shaft size for testing purposes? Hopefully the perfect ebike motor will be created here.

[enoob]

how are you going to test your motor?

sorry thud it just occured to me that you were asking what i was going to use to spin it up .

could be a good one to add to the parameters of competition ? common controllers for testing .

i was thinking this
https://www.kellycontroller.com/shop/?m ... uct_id=523
or this
http://www.hobbycity.com/hobbycity/stor ... oduct=6550

one choice is budget and i wont mind so much when it smokes, the other i have not looked into fully yet but i would be leaning to the kelly if i can rebuild it though it needs hall sensors .i think.
another outfit that shall go nameless till i get the goods i paid for will NOT be getting used for the virgin run.

[AussieJester]

I am good at implementing someone else's motor onto a bike. It is cool to see people actually start from scratch and make their own working motor.

Matt

Yes im a bit in that boat myself Matt, after rewinding an old Unite motor i had had enough much more pleasurable watching others do it IMO LoL

KiM

p.s good luck all ripper job thgus far too enoob..

[Miles]

So what are the parameters here in case one were to imagine that they could build something like this? Does it have to at least be within certain weight restraints, and spin at least within a usable rpm, with maybe universal shaft size for testing purposes? Hopefully the perfect ebike motor will be created here.

4Nm of continuous rated torque per kg of motor weight - passive cooling only - for a motor weighing under 3 kg?

[Miles]

Perhaps we need to clarify "passive cooling"?

Maybe we should allow cooling systems that are driven by the motor itself, but not those that use an autonomous fan or pump?

[TylerDurden]

Perhaps we need to clarify "passive cooling"? Maybe we should allow cooling systems that are driven by the motor itself, but not those that use an autonomous fan or pump?

Sounds like a good distinction between classes.

[Miles]

Perhaps we need to clarify "passive cooling"? Maybe we should allow cooling systems that are driven by the motor itself, but not those that use an autonomous fan or pump?

Sounds like a good distinction between classes.

For good reason, no?

[TylerDurden]

For good reason, no?

Sure.

Having the classes discrete will bring more innovation in each one.

[liveforphysics]

As a guy with an abnormal amount of exposure to contests, you're really going to need to make a rule-sheet, and choose the wording extremely carefully. Wording related loop-holes are what get most racers the win.

You can also make the broad, "Any interpretation deemed to be outside the spirit of the event" statement at the end of the rule sheet, but it kinda bogs down potential creativity, and in this contest, creative solutions/designs are more the idea rather than a fair event. My $0.02.

Just remember, the moment you make a new rule, you also open a new can of worms, so they need to be choosen and then phrased very carefully.

[Miles]

No kudos in a win that isn't in the spirit of the challenge.

[liveforphysics]

I used to feel that way Miles. After you start running against teams with massive sponsors and high 6-digit yearly budgets, and you're running a self-built grass-roots self-budgeted racing effort, you find creative interpretations of the rule book to be that bit of anything to do more than bring home, "also-ran" positions at events...

Its very tough when you gotta run a season on 1-2 engines and 2-3 trannys and 2-3 sets of tires when you run against teams that bring 2 full semi-trucks out, one having a portable machine shop and filled with engines, the other having a few chassis and 20 new slicks. I'm driving my own car there packed with tools and tires and parts, and my driver=my mechanic = my tuner = my engineer = my crewchief. Everytime we take down a factory backed team, its a proud celebration no matter how we managed to do it.

For something all grassroots, I would stick pretty close to the spirit of the event.

[Miles]

[Thud]

As a prize-less competition, I think the fewer rules(?) the better. Its not about fair or winning, its about a home made motor the meets the tourqe density requirement in the OP. (as reasonably cost effective as possible in my case)if some one has unique skills to add to their build I would like to see it.(water cooling,cold fusion,horse manure)

I like the word "Challenge" in this instance over competition. If its a "competition" I have to re-focus & pinpoint on a goal & do all in my power to WIN! (I come from a long line of competitive people)kudo's be dammed. A win is a win.

Rules & constraining critera are great for a real "competition" but they also tend to drive costs up & can bewilder some from participation. They are ment to level the playing feild. The only catagory I feel is required is "electric motor".

I would think if the need arises, we can create all the defining launguage for the motors as they present themselves

I still have the feeling this is going to be a long lived thread. So far I can only see Enoob & myself activly working on a motor build currently. In a few months or years I would hope to see some joiners.

Can we get a "roll call" from those who plan to build one someday? even if its a knock off of a proven design.
or a cad model to share. That could be another catogory.

[Miles]

How about:

Over 4Nm continuous torque per kg of motor weight.

Less than 3kg in weight.

No energy input other than that to the motor itself.

Capable of practical use on an electric bike.