HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 05, 2011, 10:32 PM
Destroyer of G-10
askman's Avatar
United States, OR
Joined Jul 2004
10,085 Posts
I purchased bunch of 4mm x 49mm shaft from rctimer and 4mm collet adapters and replaced all the shaft. I have old and newer dt750, and replaced all the shaft on them for my multicopters. have not run the newer version with flat magnet yet, but will soon. I do like the bigger bearing on them, as they are easier to find and replace, not to mention easier to find the e-clips for the newer ones. I also think bigger tube has thicker wall and has added durability. changing to collet really made it easier for me to run APC props and seems much smoother. I did cut the 49mm shaft down a bit to 46 or so and ground a flat for the nut, so it sit flush with the bell. I also retapped all the set screw to 6-32. made it much stronger. happy with how it is performing.

probably should stick with 3S, but I have lot of 4S packs and as long as I don't abuse the power, I should be ok I am hoping. .

I am running 4S/11-4.7 prop, but I am rarely over half throttle, so it is coming down cold.
askman is offline Find More Posts by askman
RCG Plus Member
Sign up now
to remove ads between posts
Old Dec 05, 2011, 11:08 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,218 Posts
What 11 x 4.7 prop are you using? I never got far on the DAT-750 with the GWS slow fly props because they would start fluttering so soon. The Great Planes work good for me though. But you have to have counter rotating props for a multicopter, right? Some of the prop sets they sell for the multis can get pretty expensive.

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Dec 06, 2011, 02:36 AM
Registered User
imdone's Avatar
United States, WA, Seattle
Joined May 2011
806 Posts
can I run 4s with the dt750's?
imdone is offline Find More Posts by imdone
Reply With Quote
Old Dec 06, 2011, 11:10 AM
Destroyer of G-10
askman's Avatar
United States, OR
Joined Jul 2004
10,085 Posts
I am using APC props SF, I am rarely over half throttle, so I have no issue flying it at 4S. things come out cold . things are smooth. smooth enough for doing video. GWS props is lousy. graupner has 11-6 props in cw/ccw set I believe and it has good rep. but spendy. I just like having lot of power margin, and I have lot of 4S packs, so it worked well for me.

you can run 4S, but you really have to watch the current/temperature. if you like to go full throttle a lot, I would not go over 10" prop. as long as things stays cool, it should be fine. at 30amp, you are talking 400+ amps on 4S. at 80% efficiency, that is still 80watt of heat to dissipate. with flat mags, you also lost some efficiency of heat transfer to the can compared to older rounded mags. heat is the enemy. I really like running higher voltage in most motors to keep the current down if I can match the prop/power.

this is video I did couple days ago. late afternoon. did not balance the props. (I need to) I do have some vib isolation in the mount though.

gopro testing with sunex lense (2 min 28 sec)


bit of jello, but not bad. gopro is lousy in lower light though. (can tell by washed out brighter area)
askman is offline Find More Posts by askman
RCG Plus Member
Old Dec 06, 2011, 09:55 PM
Registered User
imdone's Avatar
United States, WA, Seattle
Joined May 2011
806 Posts
Quote:
Originally Posted by askman View Post
I am using APC props SF, I am rarely over half throttle, so I have no issue flying it at 4S. things come out cold . things are smooth. smooth enough for doing video. GWS props is lousy. graupner has 11-6 props in cw/ccw set I believe and it has good rep. but spendy. I just like having lot of power margin, and I have lot of 4S packs, so it worked well for me.

you can run 4S, but you really have to watch the current/temperature. if you like to go full throttle a lot, I would not go over 10" prop. as long as things stays cool, it should be fine. at 30amp, you are talking 400+ amps on 4S. at 80% efficiency, that is still 80watt of heat to dissipate. with flat mags, you also lost some efficiency of heat transfer to the can compared to older rounded mags. heat is the enemy. I really like running higher voltage in most motors to keep the current down if I can match the prop/power.

this is video I did couple days ago. late afternoon. did not balance the props. (I need to) I do have some vib isolation in the mount though.

http://www.youtube.com/watch?v=jn8fhS35P8g

bit of jello, but not bad. gopro is lousy in lower light though. (can tell by washed out brighter area)
thanks! I just got some rctimer 30 amp esc's incase my 18amp plushes dont cut it.
imdone is offline Find More Posts by imdone
Reply With Quote
Old Dec 17, 2011, 02:07 AM
Registered User
manuel v's Avatar
Mexico, BC, Mexicali
Joined Aug 2004
5,387 Posts
Quote:
Originally Posted by jackerbes View Post
Here it is, 18 (maybe really 19?) turns of 22 AWG Micro Dan, Half Parallel Delta wind, and terminated "Y". It finished up with a Kv of 910 and is ready to fly!

I love this motor and this wind for it's torque and low RPM power, it is the Harley-Davidson V-Twin equivalent for brushless motors.

Notice how going to full throttle turns up the power but adds very little to the RPM once I get that prop (Great Planes 10 x 4.5 slow fly) up to 6,000 RPM or so.

Jack
Jack.

I rewound 3 turns in my 19t HP star to 16Turns HP Star for 935 Kv.

Manuel V.
manuel v is offline Find More Posts by manuel v
Reply With Quote
Old Dec 17, 2011, 06:44 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,218 Posts
Quote:
Originally Posted by manuel v View Post
Jack.

I rewound 3 turns in my 19t HP star to 16Turns HP Star for 935 Kv.

Manuel V.
Did you want a little more RPM? Was that the reason?

The wind I've used the most for this is 18T 23AWG Half Parallel Star and it get me about 835 to 855 or so for a Kv. I could use 22AWG if I had it but 21 was just a little too much for my hands.

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Dec 17, 2011, 01:45 PM
Registered User
manuel v's Avatar
Mexico, BC, Mexicali
Joined Aug 2004
5,387 Posts
Jack.

Mine it was 19turn HP star for 826Kv. but now Im using APC e 11x7 and need more rpm.
Now with 3turn less it have 935 Kv.
Very easy unwind 3 turn in HP wind for new Kv.

Im going to test today.

935Kv is close to 14 turns DLRK Delta.

Manuel V.
manuel v is offline Find More Posts by manuel v
Reply With Quote
Old Dec 19, 2011, 07:41 PM
Registered User
manuel v's Avatar
Mexico, BC, Mexicali
Joined Aug 2004
5,387 Posts
Check your tachometer battery.

I think, i have a low battery in my tachometer.
maybe im lost 3-4% in my reading.

Today, i test my 16Turn HXT 750. for check Kv. and only have 820.
ever reading 860Kv.

My 935 maybe is bad. and correct Kv is around 970. same turn calculator prediction.

Manuel V.
manuel v is offline Find More Posts by manuel v
Reply With Quote
Old Dec 20, 2011, 12:21 PM
Registered User
manuel v's Avatar
Mexico, BC, Mexicali
Joined Aug 2004
5,387 Posts
Anyway,

My test:

GWS 9x5, 3slipo, 8700rpm, 11.90A, 11.86V.
GWS 10x6, 3slipo, 8200rpm, 16.46A, 11.70V.

Test no load. rpm/v data.
1 test. 10200rpm, 1.67A, 12.45V, 819.27Kv.
2 test. 8800rpm, 1.54A, 10.73 V. 820.13 Kv.
3 test. 5900epm, 1.10A, 7.12V. 828.65 Kv.

Kv= RPM / (Vin-Vloss)
Vloss= Iin * Rm.
were:
Rm is for Drive calculator.

Kv=10200/(12.45-(1.67*.0873))= 829 Kv.

Test no load to different time.

High. 10400rpm, 1.76A, 12.27V., Kv 847
Medium, 10,000 rpm, 1.63, 12.14 Kv 823
Low, 10,000 rpm, 1.62, 12.13V, Kv 824.


My test with the drill press does not work well on this engine as it gave me a 960-kv.

larger engine gives me a more accurate kv.

Possibly the unreliability of the AC meter to less than 2 volts.

Lecturas,Vpeak,RPM drill,Constant,Ke, Inv Ke, ....... Kv.
1.4 1.9796 2000 0.5 0.0009898 1010.305112, 960
1.4
1.4

Manuel V.
manuel v is offline Find More Posts by manuel v
Reply With Quote
Old Feb 01, 2012, 10:30 PM
Registered User
Joined Jan 2012
8 Posts
Problems with the hexTronik DT700 Brushless Outrunner 700kv from hobbyking

We have a problem with all 6 of the hexTronik DT700 Brushless Outrunner 700kv from hobbyking. With a Prop APC 11x3.8 as suggested and 18A turniggy Plush the motors make a high pitch noise on throttle changes and then collapse in energy.

We planned to use them for a Y6

Full throttle can only be achieved if I pull the throttle up slowly. if I move it up and down the motor collapses.

Is this an error of these motors or can it be something else?
PROBLEMS with Hextronic DT700 with APC12x 3.8 from hobbyking (0 min 58 sec)
manuelo is offline Find More Posts by manuelo
Reply With Quote
Old Feb 02, 2012, 08:23 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,218 Posts
Quote:
Originally Posted by manuelo View Post
We have a problem with all 6 of the hexTronik DT700 Brushless Outrunner 700kv from hobbyking. With a Prop APC 11x3.8 as suggested and 18A turniggy Plush the motors make a high pitch noise on throttle changes and then collapse in energy.

We planned to use them for a Y6

Full throttle can only be achieved if I pull the throttle up slowly. if I move it up and down the motor collapses.

Is this an error of these motors or can it be something else?
That is a larger slow fly prop, it is very likely that you are pulling more than 18A. When you ease up to full throttle the ESC is keeping up with it, when you make the sudden movements the sudden load causes the current peaks to be a little higher and either the LVC or over current protection might be kicking in.

Try it with another larger ESC and see if it happens.

The prop testing on that motor with a 11 x 4.7 APC SF prop had that motor pulling close to the 18A max rating of your ESC so it makes it even more likely that you are exceeding the ESC's limits.

If you want to get good service from the cheap imported ESCs you should down rate them to about 75% of what they rate them at. That 18A ESC is best used at 14A or less, for 18-20A loads you should a 25A or larger ESC.

And you need a watt meter to really see what is going on in a power system.

I have to ask, who and what would fly using those kinds of throttle abrupt on and off throttle movements?

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Old Feb 02, 2012, 12:27 PM
Semper Fi
greedyg76's Avatar
United States, CA, Rancho Cucamonga
Joined Mar 2009
1,013 Posts
Has anyone played with this motor from HK ? Looks real similar to our DT750's. For $11, I may pick one up just to tear it down and see what it all about...

http://www.hobbyking.com/hobbyking/s...dProduct=14742
greedyg76 is offline Find More Posts by greedyg76
Reply With Quote
Old Feb 02, 2012, 12:55 PM
Registered User
St Catharines Canada
Joined May 2002
910 Posts
Yes, not recommended, get the L3010B instead.

1. the motor mount is smaller than the bell so you must have access to all sides to mount it

2. The mount is force fit. I thought it was glued but had to torch it and it would only move when hot.

3. The above toasted the bearing.

4. The shaft was prebent.

Did get up to ~360 watts at 35A 3S 2650 Flightmax but I don't remember the prop. Currently 9x3.8 EMP at ~23-25A for about 260 watts for just over 1kg thrust.

Richard
The Tellurian is offline Find More Posts by The Tellurian
Reply With Quote
Old Feb 02, 2012, 02:37 PM
Jack
USA, ME, Ellsworth
Joined May 2008
17,218 Posts
Quote:
Originally Posted by greedyg76 View Post
Has anyone played with this motor from HK ? Looks real similar to our DT750's. For $11, I may pick one up just to tear it down and see what it all about...

http://www.hobbyking.com/hobbyking/s...dProduct=14742
The 3010B is the back plate version of that motor, Manual_V posted a little info on the C version here and a link to the B version too:

http://www.hobbyking.com/hobbyking/s...dProduct=14736

Other than that I don't think I seen any more info on it.

Jack
jackerbes is offline Find More Posts by jackerbes
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
lrk-torquemax diy brushless outrunner kit Ron van Sommeren Power Systems 2 Dec 22, 2011 08:45 AM
For Sale hexTronik 24gram Brushless Outrunner 1700kv tallflyer Aircraft - Electric - Power Systems (FS/W) 3 Jul 10, 2007 10:49 PM
English lrk-torquemax diy brushless outrunner site & mailing list Ron van Sommeren Electric Plane Talk 0 Sep 29, 2001 06:57 PM
E-fly-in&diy brushless outrunner meeting, Sept. 2nd, Winssen/Nijmegen,the Netherlands Ron van Sommeren Electric Flight Events 1 Aug 02, 2001 06:37 AM
diy brushless outrunner/LRK meet & E-fly-in, Sept. 2nd, Nijmegen, the Netherlands Ron van Sommeren Power Systems 0 Aug 02, 2001 06:32 AM