An Advanced Friction Drive System

[Miles]

I thought the whole idea of outrunners was to avoid the gearbox....?

A 5% increase in efficiency for a motor starting at 85% means around 20% to 25% less heat......

Anyway, I shouldn't really take up Kepler's thread with this....

 

[deVries]

Most RC controllers I've tested seem to handle Delta better than Wye (though that could be timing issues and such) but as luck would have it, once halls are fitted... the little Infineon controllers do a pretty good job in either termination and seem to handle on the fly changes to termination better than say an HV110?

Sure would appreciate it if someone knows of an existing thread that shows how to install halls in an RC motor; or, if none existent, then someone experienced doing this would start a thread that shows a step by step w/pics how to do this. 8)

TIA.

Edit: I did find this thread about installing hall sensors in RC motors: http://endless-sphere.com/forums/viewtopic.php?f=30&t=15686

 

[Kepler]

My riding mates decided they would tackle the a challenging Mount Dandenong tourist road today. I figured this would be a great opportunity to see if the drive would handle the long constant 12km up hill run. So this morning I loaded up my Headway 10ah 6S pack for some added endurance and headed out. The ride started with a 10km stint to the base of the hill. The run up the hill is actually used for completion time trials and there were plenty of comp riders heading up.

So the assent started and right from the start I activated the drive to stay with my much younger and stronger riding mates. My work load was constant but not uncomfortable and actual load on the drive was surprisingly light at around to 200 to 300 watts. Wasn’t long until a group of comp rides powered past us so I decided to see if I could stay with them. A touch more throttle and I was now matching their pace. From there I stayed with them for the rest of the climb. At the top of the hill the look on comp rider's faces was priceless with them trying to work out how the hell this old bloke on a mountain bike had managed stay with them. Then someone spotted something unusual on the bike and the questions started. Ended up being a great laugh with lots digs about the drive being cheating but all was in good humour. Quite a few took pictures of drive on their phones to show their mates.

So the drive survived without an issue and even when matching the comp riders, stayed cool. Used 6ahs for the climb which I thought was more then reasonable for such a challenging climb. Left enough in the tank to get me over a few hills on the way home and ended up covering just under 50kms for the ride. A most enjoyable ride and a very successful endurance test for this tiny RC drive.

 

[bandaro]

sounds like fun, now you just need to work on making it a real stealth thing, so people just think your an awesome rider! maybe mount it lower just under the bar its currently on? put the batts inside the frame, down the seat post or something and your good to go maybe cover the drive system up with one of those tool bags that a lot of guys have under the seat?...

 

[spinningmagnets]

Since the drive-box is aluminum plate, I'm sure it provided significant heat-sinking...and I suspect the aluminum bicycle frame pulls "some" heat away also?

Was the drive box warm to the touch? was the frame near the drive warm also?

 

[plutonet]

Awesome ride Kepler..
Wow.. this thread amazes me, great design and many great contributions. I have been reading it and all related for days on end. EVTodd is great design also. Me being into photo/video thought those kinds of quick releases might work well or spark design ideas. Most are alloy. B&H has quite a variety.

What kind of a wattmeter/logger are you using for your rides? And was that the 4045 320kV motor? 6ah for 12km comes out to about 2km per ah for hill assist for your idea of a 4ah internal battery works out to about 8km of assist. Does this sound about right? These are really transformational systems. I really like the KISS approach here using inexpensive emf feedback ESC and making the system an assist.

 

[zap]

At the top of the hill the look on comp rider's faces was priceless with them trying to work out how the hell this old bloke on a mountain bike had managed stay with them. Then someone spotted something unusual on the bike and the questions started.

Is the system quieter than it seems on the videos or were you at the back of the pack and they just couldn't hear it?

Someone earlier in this thread asked for a video with the camera stationary... did I somehow miss that video?

 

[Kepler]

sounds like fun, now you just need to work on making it a real stealth thing, so people just think your an awesome rider! maybe mount it lower just under the bar its currently on? put the batts inside the frame, down the seat post or something and your good to go maybe cover the drive system up with one of those tool bags that a lot of guys have under the seat?...

There's lots of ways you could cover it up and I do use one of those under seat tool bags to carry the battery. Personally I quite like the look of it and pefer to show it off a bit. Its funny about the awesome rider thing. I actually start to kid myself I am superstar rider then i tackle a hill without the assist and quickly come crashing back to reality. :lol:

 

[Kepler]

Since the drive-box is aluminum plate, I'm sure it provided significant heat-sinking...and I suspect the aluminum bicycle frame pulls "some" heat away also?

Was the drive box warm to the touch? was the frame near the drive warm also?

The aluminim side plates are designed to make positive contact with the ESC heat sinks so yes they do provide significant heat sinking. Also the pivot plates holding the motor act as very effective heatsinks. I have had a few suggestions to make much of the drive from carbon fibre sheet. This would look very cool but I would loose this great heat sink potential. However, I am not pushing big amps so maybe carbon would be fine. Might mak a set of carbon side plates to see how they go.

 

[Kepler]

Awesome ride Kepler..
Wow.. this thread amazes me, great design and many great contributions. I have been reading it and all related for days on end. EVTodd is great design also. Me being into photo/video thought those kinds of quick releases might work well or spark design ideas. Most are alloy. B&H has quite a variety.

What kind of a wattmeter/logger are you using for your rides? And was that the 4045 320kV motor? 6ah for 12km comes out to about 2km per ah for hill assist for your idea of a 4ah internal battery works out to about 8km of assist. Does this sound about right? These are really transformational systems. I really like the KISS approach here using inexpensive emf feedback ESC and making the system an assist.

Hi plutonet, welcome to the forum. Thanks for the kind words.

I am just using a wattsup meter and only plug it in ocasionally when I want to do some new testing. Yes it was the 4045 320kV. Sounds right in relation to 8km of assist. This is plenty on a 40 or 50km ride.

 

[Kepler]

At the top of the hill the look on comp rider's faces was priceless with them trying to work out how the hell this old bloke on a mountain bike had managed stay with them. Then someone spotted something unusual on the bike and the questions started.

Is the system quieter than it seems on the videos or were you at the back of the pack and they just couldn't hear it?

Someone earlier in this thread asked for a video with the camera stationary... did I somehow miss that video?

It sounded like a screaming banshee in the video i know, but its really not that bad. At part throttle, its just a bit of background noise. At full throttle my mates tell me it sounds like they are getting overtaken by a turbine powered bike

 

[katou]

Clearly this is the next step for you.

Bring on the turbines.

Katou

 

[Kepler]

Just for you Katou http://video.google.com/videoplay?docid=-5437209871684663077#

 

[katou]

You could SO do better than that. They're using turbine to push air, very ineffective when you are connected to the ground. Now, if you used the turbine to drive the wheel like these guys are driving a prop...

http://www.turbinemarine.com

Well, that would be a different kettle of fish. Flying fish.

Katou

 

[deVries]

Have ordered a Turnigy K-Force 100 6S ESC to test next week so this should be interesting on how it compares to the Castle Creations. Its supposably got a quicker CPU to help out sync issues and also has a nice soft start.

Please give us your findings by comparing these two ESC pro/con.

Thanks!

 

[ITgreybeard]

Let's see if I can do some calculations accurately:

45kph = 1250cms.
With the 4045(Zs[=new model]) at 49mm diameter, its circumference is 31cm (no sleeve).
At 1250cms, the can is doing 40rps aka 2400rpm.
At 65kph the rps is up to 58rps aka 3500rpm.

That's nicely under the 4045's max listed propeller turns listed at 7800rpm.
Is the motor operating well within its efficient range? (I don't see an efficiency curve on the Hyperion website, and don't know the technology sufficiently well to guess.)
Is there any reason that the can itself would not be up to the strain of being the turned component?

Do I understand that more turns yields more torque and fewer rpm, all other things equal?
Would you want a motor with more turns for hilly country? (Might need more battery too..)

Thx, and congrats!

 

[ITgreybeard]

Oops. My question about whether the can will take the high turns reflected my ignorance of the technology, I now understand. If my updated understanding is correct (via http://endless-sphere.com/forums/viewtopic.php?f=28&t=7409&start=15), the can on an outrunner turns as part of its ordinary function.

 

[Miles]

Do I understand that more turns yields more torque and fewer rpm, all other things equal? Would you want a motor with more turns for hilly country?

More turns gives you more torque per amp. The heat generated for a given torque remains pretty much the same. The continuous torque rating of a motor is determined by its ability to dissipate heat........

 

[Kepler]

Real world testing sees 50kph at full throttle with the 320kv motor. The Ebike speed calulator predicts a similar outcome. Something isnt quite right with you calc.

Efficiency may suffer a bit at lower RPM but still quite acceptable. I am about to test a 250kv motor which I will try on both 5S and 6S.

Let's see if I can do some calculations accurately:

45kph = 1250cms.
With the 4045(Zs[=new model]) at 49mm diameter, its circumference is 31cm (no sleeve).
At 1250cms, the can is doing 40rps aka 2400rpm.
At 65kph the rps is up to 58rps aka 3500rpm.

That's nicely under the 4045's max listed propeller turns listed at 7800rpm.
Is the motor operating well within its efficient range? (I don't see an efficiency curve on the Hyperion website, and don't know the technology sufficiently well to guess.)
Is there any reason that the can itself would not be up to the strain of being the turned component?

Do I understand that more turns yields more torque and fewer rpm, all other things equal?
Would you want a motor with more turns for hilly country? (Might need more battery too..)

Thx, and congrats!

 

[ITgreybeard]

Oh, I wasn't predicting 65kph, but thought I had seen it as a target speed. Now that I've reviewed the entries, I see a 6S not a 65. <-- older eyes, you know...

A nice feature of the friction drive (or whatever it might be called*) is that its performance does not depend on wheel diameter, in contrast to a hub drive.

I've now installed 3 24v hub drives, 2 on recumbents that I own, and one on a friend's mountain bike. They operate well enough but are quite heavy, have rather modest torque, and introduce a fair amount of spin-drag when not being asked to work. Your setup has the advantages of being lightweight and drag-less when not employed.

If I had my druthers, I'd prefer to have a motor operate via the crank, in order to take advantage of the derailleur system's speed/torque tradeoffs, but every such setup that is out there seems to get way over-involved.

The seat-post installation system would very likely work for >50% of bikes out there, better than any other single means of attachment. You might want to consider for v4 or v5 a modular attachment system, so that folks with soft-tail bikes and recumbents and touring setups with rear racks could still consider the product. It would be interesting to see other contributors' comments about attachment.

Best to you, and btw your Youtube videos are great.


* including the KRAPPPS [ha!] moniker suggested by one reader

 

[Kepler]

Thanks ITgreybeard,

Trying to adapt the Mk3 drive suit as many bikes as possible has been a real challenge. But with a system whereby a few different size spacers are used to adjust the distance of the drive from the seatpost, I think I have managed to extend the range of bikes to maybe as high as 80% of bikes. Taller bikes like 29ers and large frame road bikes are the most difficuly to fit to due to the distance from the seat post to the wheel. However, so far the mout suits medium to small frame road bikes, the majority of mountain bikes and BMX type bikes (with the seat up a bit). Havent tried any folding type bikes yet but I will test some of these soon. I am now re designing a triangle mount to suit the Mk3 drive also to further extend the range og bikes.

Hopefully I can have some pictures up in the next few days showing Mk3 drive fitted to a varity of bikes.

 

[morganw]

What happened to the drawings? Based on a quote of this post, I think they were attached, then edited away. Can they come back?

Please?

 

[spinningmagnets]

I think there's quite a demand for these, he may now wish to produce these for a couple years before the Chinese start copying them. Even if he patents the design and then just licenses the patent, this design is something really new and wonderful.

You have all the information you need to copy this for your own use. Make one out of wood first. I recommend particle board to finalise dimensions.

 

[EVTodd]

I think there's quite a demand for these, he may now wish to produce these for a couple years before the Chinese start copying them. Even if he patents the design and then just licenses the patent, this design is something really new and wonderful.

You have all the information you need to copy this for your own use. Make one out of wood first. I recommend particle board to finalise dimensions.

I agree someone should start making these to sell. I'm not sure about a patent though. I'm pretty sure there have been a ton of patents on pivoting friction drives over the years. In fact, I seem to recall that being one of the reasons ev warrior had to stop selling their drives.

 

[AussieJester]

Agreed definitely should look into producing these, i also don't see a patent
being worth the paper its written on the Chinese obviously don't they
will copy it either way, this could actually be the first full rc motored kit
to be mass produced and easily installed on variety of bikes in minutes.
To top it off the inventor of it is an Aussie well done Kepler

KiM