HobbyKing SK3s

[Erogo]

http://t.co/VKHtcLk

They claim to have them at hobbyking HQ, and just need to list them on website for sale.

Gents, to the piggybanks!

 

[adrian_sm]

Bring it on.

Wonder what the prices are going to be?

Model:

SK3-2118-3100KV
SK3-2122-2100KV
SK3-2822-1740KV
SK3-2826-1240KV
SK3-2830-1130KV
SK3-2836-2500KV
SK3-3530-1460KV
SK3-3536-1400KV
SK3-3542-1185KV
SK3-3548-1050KV
SK3-4240-740KV
SK3-4250-500KV
SK3-5045-660KV
SK3-5055-430KV
SK3-5065-236KV
SK3-6354-260KV
SK3-6364-245KV
SK3-6374-192KV
(more...)

 

[Erogo]

Yeah, exactly. I think there'll be some upset folks when the prices are released, given the scarcity of neodymiums.

You reckon they'll do some good ones with skirt bearings, just good for a commuter booster? I wanna stick a friction drive on an old cast iron frame I've got that I'm gonna put a nuvinci drive in. I reckon pedalling through the auto-nuvinci and friction drive are a killer combo. (is a killer combo?)

Eric

 

[adrian_sm]

SK3 motors are starting to appear on the site.
http://www.hobbyking.com/hobbyking/store/uh_listCategoriesAndProducts.asp?idCategory=250

But only the small ones. Biggest they have listed so far is the Turnigy Aerodrive SK3 - 5055-280kv, for $39.

So price is on par with the previous AerodriveXP motors like these:
http://www.hobbyking.com/hobbyking/store/__7071__TGY_AerodriveXp_46_SK_Series_50_55_580Kv_1580w.html
http://www.hobbyking.com/hobbyking/store/__7709__TGY_AerodriveXp_90_SK_Series_50_65_270Kv_2100W.html

Now hopefully they will list some bigger motors soon.

- Adrian

 

[Miles]

What do they mean by a "string wound stator"....?

 

[full-throttle]

What do they mean by a "string wound stator"....?

Maybe the guy who winds it is named String?? :wink:

 

[Miles]

I guess it's unlikely that they got better results by replacing the copper with their packaging twine....

 

[adrian_sm]

Maybe something like this, to keep the windings where they should be ?

ref: http://www.rcgroups.com/forums/showthread.php?t=1324088&page=7

 

[Miles]

Maybe something like this, to keep the windings where they should be ?

Ref: http://www.rcgroups.com/forums/showthread.php?t=1324088&page=7

Thanks Adrian. I expect you're right.

 

[Erogo]

Cool about the pricing! Glad I was wrong about that
I guess if these replacements had been more pricely it'd have been hard to put them up against the previous stock. Must be that neodymium shortage hasn't come through too hard yet?
Eric

 

[HumboldtRc]

Hopeful they use roll pins, like it that picture, also!!!! Because the glued on stators, on the old ones, would break loose and spin on the mounting tube.

 

[Erogo]

Several of the SK3 models are shown as Back Order, several have three left in stock, some just six, and others 10+. None of them have "lots". Is this a run on the new stock as well?

 

[Hillhater]

more appearing "in stock" , but odd descriptions ?
such as the popular 63-64 series, which now seem to be actually 59mm diameter, shorter by 10mm , and lighter by 200gms.?
and the shaft is smaller at 8 mm
Price not changed much tho'. @ $64
http://www.hobbyking.com/hobbyking/store/__18181__Turnigy_Aerodrive_SK3_6364_190kv_Brushless_Outrunner_Motor.html
Specs.
Turns: 18T
Voltage: 10S Lipoly
RPM/V: 190kv
Internal resistance: 0.028 Ohm
Max Loading: 65A
Max Power: 2450W
Shaft Dia: 8.0mm
Weight: 697g

 

[adrian_sm]

Sold.

Just bought 3, and I got last 5055-280kv as well.

If they perform, I'll sell them as complete kits, bundled with my drive, esc, and my new interface. Basically ready to roll except for batteries.

- Adrian

 

[adrian_sm]

more appearing "in stock" , but odd descriptions ?
such as the popular 63-64 series, which now seem to be actually 59mm diameter, shorter by 10mm , and lighter by 200gms.?

Probably the more comparable motors are the 6364 ones like these, similar weight/size, but higher kv, lower price.
TGY AerodriveXp 160 SK Series 63-64 230Kv / 3150W

Turnigy 63-64-A 280Kv 65A Brushless Outrunner (52-30)

- Adrian

 

[Hillhater]

The Aerodrive series do not have shell bearings, ( not 100% certain on the SK3's either ?)..and i think all of the "gold" 63-64 's are sold out.
i like the lower KV and the smaller diameter suits me for a friction drive, just not so comfortable with the smaller shaft dia.
... and I just hope that the weight reduction is not at the expense of copper fill ? :?

 

[Erogo]

I thnk I saw them announce somewhere that there would be more model varieties arriving weekly. So 6364s so far, what next week?! And check out how many of the larger sk3s that came out last week have sold out already.

Adrian do you know if those 6364s have a skirt bearing? I see a wee grubscrew there, would that indicate skirt bearing?

Eric

[edit: sorry hillhater, missed your post there before putting mine]

 

[adrian_sm]

The first post link mentioned a SK3-6374-192KV plus more ... So probably some bigger ones to come.

As for skirt bearing, I am just guessing based on pics and stats, but I think it does. So not as worried about 8mm shaft. Time will tell.

 

[Hillhater]

not all the SK3/63 series motors appear to have those screws in the bell that are normally an indication of a skirt bearing, and most of these SK3's are considerably shorter ( 10-20mm) than their "gold" equivalents ( skirt bearings need extra casing length),.. ...hence why i am not yet confident that skirt brgs are installed in all these SK3's.

 

[adrian_sm]

Larger 6374 models (149kv, 168kv & 192kv) are now listed for $76, but are all on backorder. :?

8mm shafts
Skirt bearings.
Integrate "fan".
59mm outer diameter

 

[georg2410]

Hi All,


after reading through the biggest thread with over 70 pages, I got stuck to the idea of starting a friction drive conversion of my old bikes, too. Great job you did up to now ... wonderful forum

I would like to ask the specialists among you :

Has anybody already gained some experience, or even measurements, with the Turnigy SK3-6374, especially with the KV149 version ?

HK's technical data is somehow confusing (1265 g weight in the product list, 840g in the product details page), and also the 21mOhm resistance looks very low, compared to anything we've ever seen on stock 6374 motors of most cheap CN-brands.

If all published data is true, this looks the most suitable motor ever for the outrunner friction drive, having lots of reserves even for steep hills.


Many thanks in advance for any information about these new motors.

Georg

 

[Miles]

Hi Georg,

The higher weight given is the gross weight for shipping.

I think that, as you suspect, the value given for Rm is wrong. Maybe the decimal point is in the wrong place? That would give a more believable performance. Otherwise, it's a bargain

 

[georg2410]

Mhhh....

after comparing with Hacker A60-18L KV149, which has, except of 100g more weight, nearly the same dimensions, specs, and stated resistance, I don't really believe to a misplaced decimal point.

Just the roughly 50mOhms of the 6374KV170 from Aeolian, EMP and a third one from *bay made me think about this.

Ok, HK might have learned from the community and all the guys rewinding their motors, and went away from the fine stranded wires to thicker ones.

Perhaps I should give it a try ...

Thanks

 

[Miles]

The number of strands per turn isn't going to make a huge difference.

The SK3s seem to be worse than the previous SKs, performance wise....

I wasn't entirely serious about the decimal point. I'd have expected an Rm somewhere between 50 mOhms and 100 mOhms. At 21 mOhms, it out performs the Scorpion motors.....

 

[Miles]

SK3 6374 18t

Weight 0.84 Kg

Kt 0.064 Nm/A

Rm 0.021 ohms

Km: 0.064 / SqRt [0.021] = 0.44

Specific Km: 0.44 / 0.84 = 0.53