Numbers on Hobby King NTM motors

vk2dxn

Senior Member
Your welcome mate

As RC said look for an ESC with a "Bec".
The first esc I ever got was a mystery 100a esc without Bec and not knowing what a Bec was for I went ahead and connected it all up only to find that I had no control and the motor was beeping giving the "I have no control signal" beep. I then descovered that the RX had no 5v so I soldered in a LM7805 voltage regulator in to power the RX and servos. You won't hurt anything by not having a Bec it's just that it won't work without the 5v needed to fire it up.
 

vk2dxn

Senior Member
The esc seems good,
I don't have enough experiance with higher kV motors to offer an opinion.
I am a fan of low kV with bigger props but that's just me.
What was your intended setup? Plane type, weight, fast fly/slow fly ect. Sorry if you have posted it before however I am posting from my phone and can not remember the first couple of posts.
 

vk2dxn

Senior Member
Sorry
Just read the first post, you intend to run a large versa for fpv with heavy lift?.
A combo I have been playing with is a ntm28-30s 800kV with 12x6 prop. Has 1.2kG thrust on W.O.T. And relatively low current draw running on 4s. Only need a 30amp esc.
 
That may be my next motor/prop next month to experiment with =) I am hoping for decent speed/ long flight times and not blazing speeds/shorter flight times
 
vk2dxn what kind of flight times are you getting with it? What are you flying that in? And what does W.O.T mean? lol thanks noob here
 

vk2dxn

Senior Member
Hey rigo
I am using this setup in a quad with a 4s 4500mah lipo getting about 17min on hover time, as yet I have not measured the current draw.
My next build is a fpv wing that I want to run this setup with.

W.O.T. Stands for wide open throttle
 
I got the motor and esc and tested it last night. I connected my Turnigy Mega 7 in 1 multi meter to it and checked how much draw I was pulling with a 9X6, 8X6, and 7X6 prop. I was surprised that the 8X6 prop pulled a max of 79 Amps ! According to HKs wed site its max is 65A, should I not use it with that size prop?
 
Here are some pics of my results 993449_10151825194251359_1890619826_n.jpg 1468580_10151825194346359_1747506514_n.jpg 1451410_10151825194666359_68296760_n.jpg These were af full throttle after the ESC was calibrated, and I only held it open just a few seconds until I saw the Amps hit its highest
 

xuzme720

Dedicated foam bender
Mentor
I got the motor and esc and tested it last night. I connected my Turnigy Mega 7 in 1 multi meter to it and checked how much draw I was pulling with a 9X6, 8X6, and 7X6 prop. I was surprised that the 8X6 prop pulled a max of 79 Amps ! According to HKs wed site its max is 65A, should I not use it with that size prop?
Larger props will cause the motor to pull more amps, which is why you need to check amp draw with a meter. Basically, using that prop will put you over the max rated draw for that motor. Max rated draw is what the motor can withstand with out damage or burning out. So if you see more draw than rated, prop down, go to a smaller prop. The motor will probably be ok drawing over max in a burst of a few seconds, but it's much better to have the motor draw less than rated amps at full throttle if you want the motor to last awhile.
 
Hey Lonewolf, have you checked the draw on this setup? have you had any issues with the speed control/motor/prop setup and how long have you been running this setup? I take it you don't fly full throttle the whole flight but reserve it as "emergency power" ?
 

lonewolf7717

Senior Member
Hey Lonewolf, have you checked the draw on this setup? have you had any issues with the speed control/motor/prop setup and how long have you been running this setup? I take it you don't fly full throttle the whole flight but reserve it as "emergency power" ?
The "run-up" numbers must have fallen out the back of my head to make room for something else. Give me about 30 mins and I will post vid running both a 9x6 and 10x5 on the wattmeter.
 

lonewolf7717

Senior Member
ok, scratch the vid.....forgot how much gopros suck in an interior lighting situation. Keep in mind this is a 2yr old motor with a lot of hours on it and some possibly "saggy" 2650mah 3s lipos.

APC 9x6E= 54.33amp @ 590.1w
APC 10x5= 49.41amp @ 536.2w

Now thats hot off the press. I do believe i was a little over 600w on the 9x6 back in the day with fresh outta box lipos and new motor.
 

lonewolf7717

Senior Member
The foam fighter guys got substantially better numbers than I did on the 10x5 on 3s (see video). Couple things come into play, I didn't use my freshest lipo and I could play with esc timing a bit to improve numbers. Quite frankly this motor does far more than i need as is, pushes fpv 52" wing vertical without complaint and level flight at 65-70mph. Its a beast no questions asked. On 4s with smaller prop and on my FF-Aurora it gave my highly prized GraysonHobby Monster Jet a run for its money (see video, last few passes were on the NTM). Oh and its ok to laugh at my launches.....i built a plane i was scare to death of....large part of me wanted to throw it and run. Once I got over my fear it became one of my most favorable scratchbuilts to date.
 
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lonewolf7717

Senior Member
its should be noted.....if anyone else noticed my apm draw went up with the smaller prop. This is a good practice test in finding the best motor/prop combo for fpv efficiency. The 9x6 although smaller in diameter has a more agressive pitch (even one step up or down can make a ton of difference), hence higher prop speed coupled with more pitch increases amps and speed. The larger diameter 10x5 is a better option for fpv, not quite to top speed of the 9x6 but more than enough grunt for fpv with lower WOT amp draw. The general rule is the smaller the prop the less the amps but not always the case when playing around with pitch.

Larger prop/smaller pitch= brute torque, lower top end
Smaller prop/larger pitch= low on torque, fast as greased lightning.
 

xuzme720

Dedicated foam bender
Mentor
That aurora is QUICK! The first launches look like mine on the Versa before I got the Swedish Sling perfected. Kept throwing it like a frisbee and giving it too much spin...I need to build one of these and an Alphajet also. They both look like a ton of fun!