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Old Oct 10, 2012, 02:08 PM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,611 Posts
Gents,
I have the bulk 716 motors with 1mm shaft, red/blue wires. The LB and all other micro quad motors are a bit more powerful 720 type. We still need to find a decently priced bulk source for those... I just recently used a bulk 716 motor on my v939 to check and test a right rear nodding issue to see if it was motor related. I was surprised that even though it is a lighter(716 = 2.4g vs. 720 = 4.6g) less powerful motor, there was no difference in the flight performance of the v939 to include fast climb outs. So maybe there are differences in the motors that they sell on Aliexpress? There are two places to that sell them on Ailexpress now too:
-- http://www.aliexpress.com/snapshot/110827778.html
-- http://us.aliexpress.com/snapshot/20...Redirect=false

I did bin one of those bulk motors that I noticed the red wire was hanging on by one strand. There is no way to fix or re-solder that as it goes through and into the motor housing.

BTW during the 716 motor substitution test the v939 right rear nodding was still there and I eventually found it was a bad FET. And it was actually the left front FET. The nodding was from the left front speeding up sporadically and not a weaker right rear motor as I had previously suspected. The FET is marked A2shb. They are used on both the V929 and V939. I scavenged/borrowed an FET from one of my spare V929 flight controllers and it has been working fine since then. They are N-channel MOSFETs in the SOT-23 package. Mouser has them as http://www.mouser.com/ProductDetail/...2bupjU7jlOk%3d

A2shb MOSFET Data Sheet: http://www.mouser.com/ds/1/302/SI2302DS-56372.pdf

Cheers,
Jim
Quadrocopter and Tricopter Info Mega Link Index

Quote:
Originally Posted by dave1993 View Post
i dont have a v939 but my s107 and .7mm ali motors have more than enough lifting pwoer for my diy even with camera. it even beats my friends lb. 23 grams with 138mah battery for the 30cm one and 28 grams for the 60cm. a 600mah battery only adds about 10 gram so it dont look like weight is the problem. maybe this aliexpress dealer is not a reliable source although 2 guys who dont post here had no trouble lifting with them. and at least 3 guys are using the s107 motors from focalprice w/o problems. dj also said his lifted ok but i forgot what type of motors.

maybe its good i didnt change the parts list in post #1 because those motors are known to be ok. there are at least a dozen sources for 7mm motors so maybe its time to compile a list and keep track of what works. my 1mm ali motors should be arriving shortly so that will be interesting.
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Old Oct 10, 2012, 03:10 PM
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I believe the difference is RPM speed.The are motors with the same size but different RPM.Some with 10000,18000 RPM ,some 34000,other 45000,or 48000 rpm.Prices are different also.I believe the motors with unspecified rpm speed are with the lowest speed maybe around 10000-18000rpm ,cheapest also.
You can check the motors speed you have with a tachometer and compare.It will be nice to have a speed comparison between stock motors or stock vs others.Maybe the similar flight performance between different size motors 716 vs 720 is speed related.

http://www.aliexpress.com/wholesale?...tId=0&manual=y
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Last edited by midelic; Oct 10, 2012 at 03:19 PM.
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Old Oct 10, 2012, 04:02 PM
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I've just tried my aliexpress 7mm motors on my v929/v939 (v929 board & frame + v939 motorarms and holder) hybrid again.
No punch, barely lift :-( Can't turn without loosing height
My 7mm motors seem to be crap :-(
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Old Oct 10, 2012, 05:07 PM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,611 Posts
Micro multicopter motor RPM tests 101

M,
Yes. The 716s are listed at 10K "or more" RPM. I think the specifications on all the micro motors I've reviewed are wags...I just did a test with an optical Tachometer. It was necessary to balance the props with reflective tape. I did my best to move/yaw the quad to get the most RPM out of the motors for the max RPM test.
Max throttle Props on Results:
V939 motor/prop=18.5K RPM
716 motors/V939 props=12.5K RPM

Note: I measured hover speed by hand lightness and it was about 8K RPM.

So as suspected the 716 bulk motors are underpowered when compared to the 720 motors. They might OK work on a lightweight frame.

I think it flies OK in the test I did mixed with the 720 motors possibly due to the 2.2g lightness difference on the 716 arm and the fcb compensating for level...guessing. I just had to put it back to retest this but found that on punch outs I do see now that it tends to lean into the 716, but stick compensation brings it back to level.

Bottom line again...we need to find bulk pricing on 720 motors that run at about 20K RPM
*EDIT: I just found this, but you probably have to buy huge numbers of them: http://zxdmotor.en.made-in-china.com...D7PK16-Y-.html

Note: All tests were done with a fully charged lipo at 4.2v.

Cheers,
Jim
Quadrocopter and Tricopter Info Mega Link Index


Quote:
Originally Posted by midelic View Post
I believe the difference is RPM speed.The are motors with the same size but different RPM.Some with 10000,18000 RPM ,some 34000,other 45000,or 48000 rpm.Prices are different also.I believe the motors with unspecified rpm speed are with the lowest speed maybe around 10000-18000rpm ,cheapest also.
You can check the motors speed you have with a tachometer and compare.It will be nice to have a speed comparison between stock motors or stock vs others.Maybe the similar flight performance between different size motors 716 vs 720 is speed related.

http://www.aliexpress.com/wholesale?...tId=0&manual=y
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Old Oct 11, 2012, 01:17 PM
RC beginner
New York
Joined Oct 2008
6,054 Posts
ok, my 1mm replacement motors finally arrived and they are completely different from the first lot. short heavy red/blue wires instead of long thin black/white wires. case and end cap are quite different too. looks like he threw in a few extras which is nice because 1st shipment was short one. i didnt mention it to him so looks like not only is color and style random with these guys but so is count. im going to solder on some pz 1.25mm leads and see how they perform. stay tuned.
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Old Oct 11, 2012, 03:58 PM
but thats not soon enough
Denmark, Central Denmark Region, Skive
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maybe the shaft isnt the only difference on the 0.7mm and 1mm motors

mine are still in the mail. SLOW mail :/
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Old Oct 12, 2012, 03:27 AM
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You means this one?
http://www.focalprice.com/YE384S/Rep...er_Silver.html
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Old Oct 12, 2012, 01:09 PM
RC beginner
New York
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new ali motors work ok in my dquad

Quote:
Originally Posted by wapko View Post
maybe the shaft isnt the only difference on the 0.7mm and 1mm motors
you might be right wapko but im pleased to find these latest ali motors with 1mm shaft working fine in my diy quad. in yesterdays test runs they seem to have about the same power as the s107 and 1st ali batch. this is just the impression i get zipping around for a few minutes in the frat house driveway. also a couple rcgroups and offline guys have had success with 16mm motors so they cant be that bad. any real differences will be revealed when i set up the test stand and spend a day or two checking out props, motors, and combinations. we will see.

i have a theory that some people are expecting too much from low cost components or not fully appreciate the advantages of "adding lightness". one thing to remember is you can build 3 or 4 of these quads for less than the cost of a v939 and maybe half dozen for what an original walkera runs. also one might not expect cheapo motors to work as well in a stock plastic frame that weighs 4x or 5x more than the diy one. i credit the fact that my particular diy outperforms my buds ladybird, at least in lift, to the huge difference in weight. or maybe there was just something wrong with his setup or battery that day. idk. we have another "contest" coming up tommorrow. this time ill be using the new ali motors.

im pretty sure 20mm motors would have considerably more punch. i know the 8.5mm ones i tried do but they cost too much for me. hopefully we can find a cheap source of 720s like jesolins says. but power was not my biggest goal for this project. cost was and im satisfied beyond expectations. dont forget that my original dquad used 6mm solar grasshopper pagers and, while it flew quite well by itself, did not have enough extra lift to carry an 808 keychain camera. now that the v939 fc came along at lower cost a quad can be built with s107 motors instead for the same price and it DOES lift a camera. and huge lipos too.

for best performance within budget i suggest trying a super light weight bamboo frame, 16mm motors, and small cheapo pz battery. for even better power to weight ratio spend a few bucks more on some 20mm, v939, lb, udi, or whatever motors and maybe a nano lipo. if the brushless thing works out this thing will be unbelievably hot (i hope) but will NOT cost $14..
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Last edited by dave1993; Oct 12, 2012 at 01:32 PM. Reason: brushless????
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Old Oct 12, 2012, 01:34 PM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,611 Posts
Hi Dave,
That is good news That means with these .50 cent motors, it is now a $9.95 quad
.What length are the s107? Are they 7mm motors? What do they weigh?
Cheers,
Jim
Quadrocopter and Tricopter Info Mega Link Index
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Last edited by jesolins; Oct 12, 2012 at 01:41 PM.
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Old Oct 12, 2012, 04:08 PM
RC beginner
New York
Joined Oct 2008
6,054 Posts
s107 are 7mm x 16mm and have very long shaft which makes for some interesting variations (4 blade, edf, diy heli, gearbox, etc). i can also say they have much better wiring than the ali motors. longer, thinner, and take solder easier. but theres that 1mm shaft thing so whether they are worth a buck more wont be certain until i compare thrust. ive got 15 or so different 6mm, several types of 716, and one set of 8.5mm but no 720 to compare. im almost ready to spring 3$ ea for a set of those but not quite there yet. still hoping somebody will find them somewhere for a buck or two.

btw are you trying to usurp mystman as king of the bargain hunters? lol! i just added a hundred si2302 fets to my latest digikey order for 11 cents ea. at first they wanted half buck ea but i directed them to your mouser link and guess what... anyway what a deal for a cheapo nfet that drives amps not milliamps. those will come in handy repairing blown transistors and replacing bipolars for improved performance. i was able to almost double aeroace and bitcar rx thrust with that trick. thanks for the find.
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Old Oct 12, 2012, 04:35 PM
RC beginner
New York
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Quote:
Originally Posted by mystman View Post
I've just tried my aliexpress 7mm motors on my v929/v939 (v929 board & frame + v939 motorarms and holder) hybrid again.
No punch, barely lift :-( Can't turn without loosing height
My 7mm motors seem to be crap :-(
hey mystman, me thinks you need to build a bamboo stick frame. this aint to see who can build HEAVIEST frame. lol! and if that dont do it just add 4 more of those 7mmi motors. still cheaper than using any of the micro heli motors. THEN see if it still flies like crappola.
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Old Oct 12, 2012, 05:04 PM
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Quote:
Originally Posted by dave1993 View Post
hey mystman, me thinks you need to build a bamboo stick frame. this aint to see who can build HEAVIEST frame. lol! and if that dont do it just add 4 more of those 7mmi motors. still cheaper than using any of the micro heli motors. THEN see if it still flies like crappola.
Got my last hybrid (v929 board + v929 frame + bamboo arms + v939 motorholders + 7mm ali motors) flying, but not as good as the ladybird.
The motors got hot, drained to much power out of the 300mah Nano lipos and had massive problems with turning .
If I turn, the quad looses height and started wobbling :-(

Even my v929/UDI hybrid (UDI motorarms $3.20 each) has a lot more power and punch!
I'm not sure if I will giveup on this cheap-diy-quad project as my not much more expensive (<$25) plug'n'play quads fly much better and are much more reliable und durable.
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Last edited by mystman; Oct 12, 2012 at 05:24 PM.
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Old Oct 12, 2012, 05:09 PM
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I found some other 716 motors at aliexpress. Maybe these more suitable according to their rpms:

7X16 Coreless motor DC High-speed : 32000rpm / $1.80 p.p (10 a lot)
http://www.aliexpress.com/store/prod...600583456.html

7X16 Coreless motor DC High-speed : 28000rpm / $1.80 p.p (10 a lot)
http://www.aliexpress.com/store/prod...600584879.html

Both have a 1mm Shaft
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Old Oct 13, 2012, 02:51 AM
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@mystman.

It seems to me that your quad arms are too short for V929 board.my V929 with shorter arms have some wobling side to side.For this reason have M2M 280 mm.At this size is steady.

dave at the beginning of this thread specified that V929 board need 12" M2M in order to work. properly.
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Old Oct 13, 2012, 03:41 AM
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Quote:
Originally Posted by midelic View Post
@mystman.

It seems to me that your quad arms are too short for V929 board.my V929 with shorter arms have some wobling side to side.For this reason have M2M 280 mm.At this size is steady.
I had them longer (as long as the v929 arms) but the motors couldn't produce enough thrust to lift and hover higher than 1m :-(
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