Twin motored PK Ripper--A little over the top!

Thanks Matt, did you get the 5 or 6 turn version. So I can keep notes on your setup. I'm really thinking this might be a better route than the 600w BMC motor I was planning to go with on my mountain bike. Still undecided due to the work involved, but I do have my own CNC mill. Your power to weight ratio has me really interested, do you think range will be reduced due to the dual motor setup or are the efficencies good a well. Would like to know what your current draw is at just cruising speeds. If it's low, then you seem to have the best of both. I want a serious hill climber with lots of power to spare as well as the ability to go for long distances, say at speeds of 20-30mph.

They mention this version for ebikes on their site. 6turn motor
8120-6T Astro Monster 120 Brushless 6 Turn Motor
$399.95

I notice the shafts are longer, did you replace the ones on the original, if that's the case did you also replace the bearings. More details on what you did to the motors, if any please. The 4 motor mounts 6/32" was that enough?

How are you syncronizing 2 controllers. Are you just adjusting them so they seem to be putting out the same power or do you have a better method of dealing with this? I was thinking it would be possible to use a processor to monitor each motors current and throttle them up accordingly.

Kin
http://www.embeddedtronics.com/
 
:mrgreen:
8) 8) 8)

Hi Matt,

absolutely awesome bike 8)
fine choice of parts, and as ever, clinical engineering fixes to issues, how things should be done.
I'm not even going to ask how difficult programming the clamp radius was :shock: can you make me 2? :lol:
we have a guy we hope will give mine a shot so fingers crossed i'll be mounted soon too :)
theres too much to discuss without further fine inspection of the pics but just to say awesome job!!!
oh and of course the obligatory show us some vids!!!! lol
oh by the way i bought some shorts whilst snowbarding that protect the coxic(?) and butt cheeks, suggest you buy some yourself because that monster is gonna dump you on your ass for sure!! :twisted:


Cheers,

D
 
kfong said:
Thanks Matt, did you get the 5 or 6 turn version. So I can keep notes on your setup. I'm really thinking this might be a better route than the 600w BMC motor I was planning to go with on my mountain bike. Still undecided due to the work involved, but I do have my own CNC mill. Your power to weight ratio has me really interested, do you think range will be reduced due to the dual motor setup or are the efficencies good a well. Would like to know what your current draw is at just cruising speeds. If it's low, then you seem to have the best of both. I want a serious hill climber with lots of power to spare as well as the ability to go for long distances, say at speeds of 20-30mph.

They mention this version for ebikes on their site. 6turn motor
8120-6T Astro Monster 120 Brushless 6 Turn Motor
$399.95

I notice the shafts are longer, did you replace the ones on the original, if that's the case did you also replace the bearings. More details on what you did to the motors, if any please. The 4 motor mounts 6/32" was that enough?

How are you syncronizing 2 controllers. Are you just adjusting them so they seem to be putting out the same power or do you have a better method of dealing with this? I was thinking it would be possible to use a processor to monitor each motors current and throttle them up accordingly.

Kin
http://www.embeddedtronics.com/
Click to expand...

These are 6 turn motors. I had Bob make them custom with double shafts for my pairing belt drive. He did it at no extra cost, though it took a while to get done.

RC motors and controllers will sync themselves together. Nothing special needs to be done.

I am expecting to have lower efficiency with the two motors running together at lower speeds. If I had to guess (knowing what I know about RC drives) I would expect about 500 watts to cruise at 20mph. We shall see, though.

The 8120-6T is my motor (except mine have double shafts).

The mounting screws seems to be plenty for my application. We shall see soon enough!

Matt
 
I'm really considering fitting a set of these Unicycle tires on the Moby, or the next bike. My 10-speed uses glue-on tubulars, and I run my moderate quality tires at 110psi as well. They just GLIDE down the road. You can coast for days.

Competition tubulars are good for 170psi! :shock:

Anyway I LOVE high pressure tires for their super-low rolling resistance.

BSD = Bead Seat Diameter, aka the Real Way To Measure Tire Size.

Surprisingly reasonable cost for these, too. Nicely done.
 
Ahh, got ya.

I do not know the exact diameter. I can tell you they went right on to the rims using my fingers. No problem.

Yes, they are very good tires for the cost (so are Nimbus rims). I like using unicycle parts. They are designed to handle all the weight of a person on one wheel. Much stronger than typical stuff!

Matt
 
Hi Kfong,

kfong said:
I'm really thinking this might be a better route than the 600w BMC motor I was planning to go with on my mountain bike. Still undecided due to the work involved, but I do have my own CNC mill. Your power to weight ratio has me really interested, do you think range will be reduced due to the dual motor setup or are the efficencies good a well. Would like to know what your current draw is at just cruising speeds. If it's low, then you seem to have the best of both. I want a serious hill climber with lots of power to spare as well as the ability to go for long distances, say at speeds of 20-30mph.

Kin
Click to expand...

I don't understand how you arrived at these two choices. A single 600w hub motor vs a dual motor setup with each motor rated at about 2.5kW continuous and about 6kW peak?

If there is any chance at all that you would be satisfied with a 600w BMC you should not even be considering building a system with dual 2.5kW motors.

On the other hand if you really want a system with dual 2.5kW motors you shouldn't even be considering a single 600w hub motor. Its like deciding between a Honda Civic and a Ferrari.

I also don't understand your concern about the relative efficiency of these two systems. I can understand someone choosing either a Civic or a Ferrari but it doesn't make much sense to go into a Ferrari showroom and ask how the gas milage compares to a Honda Civic.

It sounds like you might be best served by a system somewhere in the middle, maybe a single motor RC System like one of the following:
Gary's RC Powered Dahon:
Note the comments on efficiency of using the bikes gears - better performance w/half the power (excerpt below):
... Anyway, with a 55A controller limit, this setup peaks out at about 2600W, but because of the gearing benefit of going through the 3-speed hub, this combo actually outperforms the 24s4p 72V 5303-based setup with a 4110-modded controller set to about 65A.

This surprising performance "boost" by taking advantage of the bike's gearing has started me on this quest now, to convert all my bikes to similar weight-saving configurations...
Click to expand...
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=8035&start=0

Matt's Recumbent:
http://www.wisil.recumbents.com/wisil/shumaker/default.htm

D's RC Powered Kona Stinky:
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=7992

Scott's RC powered FS Mtn Bike:
http://endless-sphere.com/forums/viewtopic.php?f=6&t=5168

All of these systems have massively better performance than a 600w BMC and are substantially easier to build and less expensive than Matt's dual motor system.

On the other hand if you really want a Dual RC Motor system check:
Luke's build (similar concept to Matt's PK Ripper):
http://endless-sphere.com/forums/viewtopic.php?f=28&t=8347
LiPoly powered 18HP Twin Motor Brushless MONSTER build!
Click to expand...
 
Well you said it yourself given a choice between a Honda Civic and a Ferrari. I know what I would choose. The point you are missing is if his calculations are correct. 500watts at cruising is having the best of both setups. These motors are very efficent, that was what caught my eye when Matt chose them.

On that note, hey has anyone tried the Scorpion motors.
http://www.innov8tivedesigns.com/produc ... cts_id=514
Scorpion HK-4035-400 at $169.99, these prices look very good and 2 year warranty.
No. of Stator Arms ................................................ 12
No. of Magnet Poles ................................................ 8
Motor Wind ........................................... 12 Turn Delta
Motor Wire ..................... 22-Strand 0.25mm (30 AWG)
Motor Kv ............................................. 400 RPM / Volt
No-Load Current (Io) ................. 1.38 Amps @ 8.4 volts
Motor Resistance (Rm) ............................. 0.028 Ohms
Max Continuous Current ............................... 78 Amps
Max Continuous Power .............................. 3400 Watts

From what I've read, we want a low pole count motor, because they have less syncing issues? Correct me if I'm wrong on this.
Don't know how efficient these motors are though.

Regards,

Kin
 
I used the 4035 on my first build. You will need a lot of geardown for it, and it got really hot while chugging up hills. You would be better off with a lower kv, maybe a custom wind. Something to keep it from bursting 120a when you hit a hill.
 
johnrobholmes said:
I used the 4035 on my first build. You will need a lot of geardown for it, and it got really hot while chugging up hills. You would be better off with a lower kv, maybe a custom wind. Something to keep it from bursting 120a when you hit a hill.
Click to expand...

Thanks John, you just saved me time and money. I was going to pick up one to try. Do you have any motor choices that have worked out well for you. It's looking more like the astro is a good one to go with, just wish it wasn't so pricey. This hobbby so far has outpaced my RC stuff given the short amount of time I've been in it, but I just gotta have that ultimate e-mountain bike for the trails.

Kin
 
I would recommend a motor usable on 12s lipo. If the 4035 was lower kv it would be better suited. http://www.innov8tivedesigns.com/product_info.php?cPath=21_25_39&products_id=537&osCsid=17a97f79f04d22121f5e82b2d8c44a97 that one on 36v wouldn't be bad, but still the amperage will be high when you hit hills.
 
Miles said:
If you don't mind waiting a bit:
viewtopic.php?f=28&t=9418
Click to expand...

Wow, the 55 series looks very promising. One motor setup looks feasable as well. Recovering from an ACL knee operation so I have till Aug before I can do anything risky. Currently building 2 9S8P Konian packs purchased from DoctorBass, but need to buy a charger fist. These are the batteries I will be using. 36v @ 12ah or 72v if I series the pack or 24ah if I parallel them.
 
Thank you for the recommendation on the rim. I went with unicycle tires too. :)

I have to look on Astro's site to see teh motor differences.

I was thinking about you the other day. I was looking at a set of Look Fournales linkage forks for the bike (I would shorten them to fit). But, that deal fell through.

I am looking at White Brothers telescopic forks forks instead. They are willing to modify their recumbent forks for BMX use. They are pricey, though, $610! :shock:

Matt
 
j3tch1u said:
great work on the bike matt. glad the nimbus rim fit. i'm tempted to electrify my pk now. btw, i put in an order for an astro 3210 couple weeks ago. did bob mention what the differences were between the 8120 and 3210? if the 8120 is better, i may still have time to change my order.
Click to expand...

Actually, they are exactly the same now. Supposedly before, however, the 3210s, which were $100 more, had tighter tolerences and better bearings. These motors were mostly sold for industrial/military applications. Recently, however, when they went to the new case design, the 8120s are now identical to the 3210s. Bob has been giving all of us the 3210s for the same price as the 8120s.

-- Gary
 
yikes $610!! my advice, get a pair of old girvin's and mod to fit ($75 ebay). i've got those on my bike--stripped the canti tabs, lowered the spring, added disc brake mounts, gun-sight mounts (for the dual cree quad led torches), welded alum support wings. i'm running 24x2.5 on the front with the links lowered to the max. you'd prob want to shorten the arms at the dropouts about 3 inches.
 
GGoodrum said:
Actually, they are exactly the same now. Supposedly before, however, the 3210s, which were $100 more, had tighter tolerences and better bearings.
-- Gary
Click to expand...

hi gary, i paid their list price $399 (135kv same as yours). order says still pending. did i miss out on an endless-sphere special? after seeing matt's twin-motor monster, i'm tempted to pull the trigger on another unit. how is your dahon running btw?

-ben
 
yes good question, whats happening there Gary?
also a good question, being as matt is the first mounted, wheres our testing vid? :twisted:


Cheers :)

D
 
deecanio said:
yes good question, whats happening there Gary?
also a good question, being as matt is the first mounted, wheres our testing vid? :twisted:


Cheers :)

D
Click to expand...

My progress has been painfully slow, I'm afraid. I have too many projects going at once, and a day consulting job that is taking way too much time each day ( :roll: ). I'm still building packs, still building my 16-cell individual cell charging setup, trying to help Richard get the throttle boards done, and find time to work on the Mariner. Last weekend I finally did get the drive mount problem solved, by drilling and tapping four holes to the bottom of the "foot". I then put four matching slots into the bar/plate that I have mounted on the bike, so that the mount is now firmly attached, and has about 3/4" of adjustment, for chain tensioning. I posted a picture somewhere. Anyway, this weekend I will finish up with the rest of the tasks, which include replacing the Cyclone crank with my ENO-equipped IPS crankset which has 53T and 40T chainrings, installing/adjusting the chain, wiring up/mounting the PowerJazz controller, finishing one of the throttle boards (I kept two boards and the required parts before sending everything up to Richard for assembly...) and installing a throttle (thumb version, this time...). I hope to finish all these tasks, and get this beast moving before the end of the weekend. Given that Sunday is Easter, that plan might be a bit optimistic. :?

-- Gary
 
Hey Matt - you could get real aero with this.
83091087_4c0fb97fcd_b_lg.jpg


Fairingbikes3topcrop.jpg
 
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