NTM motors for the tricopter

[Sammy]

Hi guys,

In episode 9 of the podcast I heard that the DT750 and the NTM motors appear to be the motors of choice of the Swede, so who am I to disagree? I'm rather new to the hobby, and ordered a BatBone tricopter kit (looks rad with firetruck red booms!), along with most of the electronics.

I am now considering to get the NTM motors (imo they look better than the DT750's), but there are quite a few versions (over 30 actually) to choose from, and I don't know what to look for I know that the kV rating tells you the (maximum) rpm of your motor, based on the input voltage, and that the power consumption is limited by the ESC and the LiPo type, which are 30A Afro ESC's and a 3S LiPo in my case, but that doesn't narrow the list down much ...

I read somewhere that higher kV ratings make for faster motor at the price of torque, and lower kV ratings make snappier (more torque) but slower motors. It also said that motors with a lower kV-rating are more efficient, since they dissipate less heat. Does that sound about right? And would I be right to assume that for a beginner like me it is better to go with the lower kV ratings (less top speed), or do I pick a higher kV-rated motor because it is less snappy? I know I can set dual rates / expo on my TX to keep things in check, but once I get more comfortable flying the tri, which motor will be more suited / less likely to be replaced?

Also, there are short shaft versions available for these motors, which they claim are built with no external shaft, allowing the motor to be easily mounted on the multi-rotor frame without modifications. No external shaft? Then what do you mount the prop on??

Thanks in advance for your help!

PS: looking forward to the announced multirotor beginner series

 

[jon_hill987]

With the short shaft motors you have to buy an accessory pack for the motor.

http://www.hobbyking.com/hobbyking/store/__16719__NTM_Prop_Drive_28_Series_Accessory_Pack.html

Get the one that matches the motor.

As or KV, someone with more experience should answer that one...

 

[Craftydan]

Hey Sammy! Welcome to the forum!

As for the KV tradeoffs, it is usally a trade between lift and agility -- the props are both your control surfaces and your thrust, os the trade is in the prop.

-The longer the prop, typically the more it can lift, but the motor neds to spin more slowly to keep the power down (and not stall the prop tips out on the longer prop).

- The faster the prop is spun, the shorter the prop is to keep the power down (and again, we don't want to stall the prop tips), but the slight variations in RPM needed for agility and control are easier at higher speeds.

So higher kv => short prop => more agile, lower KV => long prop => more lift.

So, what do you want from your tri? good lift for higher payloads (FPV gear and bigger batteries), but sluggish control . . . or good agility for higher performance and precise control, but limited payload and reduced flight time? Or somethign in between?

Keep in mind, there's only about 5 (IIRC) steps in the NTM motors for KV, but they're almost repeated at about 3 distinct sizes between modest to large. trying to put a large motor on a light quad will be wasted metal in the motor, but putting a small motor on a heavy quad will leave it underpowered.

For the typical batbone a 28mm might be at the bottom of the NTMs, but it's a good size. for a heavily laidened batbone carrying gear, you might want to look at stepping up a size while you drop the KV.

 

[Mustang7302]

This Motor: http://www.hobbyking.com/hobbyking/..._28_26A_1200kv_286w_short_shaft_version_.html
This Kit: http://www.hobbyking.com/hobbyking/store/__16719__NTM_Prop_Drive_28_Series_Accessory_Pack.html
These Props: http://www.hobbyking.com/hobbyking/store/__22335__9x4_7_SF_Props_4pc_R_H_Rotation_Red_.html and http://www.hobbyking.com/hobbyking/store/__22334__9x4_7_SF_Props_4pc_Standard_Rotation_Red_.html
This ESC: http://www.hobbyking.com/hobbyking/..._Motor_Speed_Controller_SimonK_Firmware_.html
This Battery: http://www.hobbyking.com/hobbyking/store/__21346__ZIPPY_Compact_2200mAh_3S_25C_Lipo_Pack.html
This Flight Controller: http://www.hobbyking.com/hobbyking/...ntrol_Board_With_6050MPU_And_Atmel_644PA.html

The motor is the lightest of the bunch, keeps weight down. The KV is on the moderate side, perfect for a 9047 prop on a Tri. The ESC has headroom to the motor and prop combination. The Battery is a good capacity for weight compromise, should get about 10 minutes of air time. The KK2.1 flight controller is the easiest flight controller to setup and get into the air successfully.

 

[Sammy]

Thanks Craftydan, adding that example of FPV vs agility has made things a little clearer I think I wanna be looking at the bigger prop, lower kV setup then. Not that I'll be flying FPV soon [being a n00b to RC it's probably better if I learn to fly (control) the tricopter first] but as it will fly less snappy, it's probably the better beginner setup.

Looks like this might be a good motor then: NTM Prop Drive 28-30S 800kV / 300W, with the accessory pack of course. Or am I dropping too low in kV and should I go for the motor that Mustang recommended (THX by the way for the detailed kit description Mustang, are you flying this combo?), being the NTM Prop Drive 28-26A 1200kV / 286W? Would 9x4.7 props do in both cases, or should I go to 10x4.5 props for the 800kV motor?

 

[Mustang7302]

I've used the 800KV NTM motors with 10x4.5" props on quads around 900 grams of all up weight. The motor and prop combo is suited well for that weight and motor count. For a fairly simple Bat Bone this should be enough lift, but you'll probably need to consider an 11x4.7" prop for hauling an extra 200-300 grams in FPV equipment.

The 800KV motors are heavier; anything you can do to save weight is a good idea. The lighter the craft is, the more resistant it will be to enduring damage in crashes ... and grams do count. I was able to shed a 100 grams on a quad (see my iQuad build) by going to lighter motors which were a higher KV, spun 8x4.5" props, and wasn't over built for the application.

I enjoying flying my higher KV and smaller prop setups. Either way is not a bad place to start, but I would recommend that you plan a second build for FPV after you have plenty of stick time on your first multicopter. Ten inch booms on the Bat Bone makes for a pretty big span and makes it moderately docile by nature, despite the KV/Prop size you go with.

Speaking of first multicopters. The best money I ever spent was flying a Nano QX by Horizon Hobby to enable to get the stick time to learn muscle memory and orientation. If I would have started there, I could have saved a lot of time and money (see my Bat Bone build).

 

[Craftydan]

I'll second the mini/micro quad for a trainer. Cheap training, easy on the pilot, and hard to break -- all that and you get the stick time you need that will transfer up. . . and you've still got something to chase the cat around the livingroom

The Blade NanoQx or 180QX are great places to start. the Hubsan X4 is also a nice quad, though not as nice for 1/2 the price. The Wakera Ladybird is also pretty inexpensive and popular, but no experience myself.

 

[Cyberdactyl]

Yea, I found the H107L X4 to be a LOT of fun, especially in expert mode.

I bought it for the Tx, to control the ProtoX, the controller for it pretty much sucks, but found the X4 and its tx to be an exceptional flying pair.

Anyway, the X4 set can be had for $42, which is a very nice buy.

I even put a 808#11 on it. It did the job and I ran it up to about 80 feet. Raw, crude and loud flying in some decent wind. Would have went higher, but it was taking full sticks to keep the wind from taking it.

 

[Sammy]

Thanks all for the good info!

Unfortunately the NTM motors are not in stock in the EU Warehouse They are in stock in the UK Warehouse, but the accessory kit is not (?). So I'll be waiting for them to be back in stock. I do however got motors from a friend who has (unfortunatley) left the hobby, Turnigy Park 300 1600kV, and some 8x4,5 SF props. I put those in the xcopterCalc and it warned me that the maximum power is over the motor's limit (172.8W calulated, 85W limit), and that I might overheat the motor (which I guess is a natural consequence of overpowering it):



Now, the funny thing is that when I use the FT recommended motor (Turnigy Park300 1380kV), I get the same warnings, and as the 1380kV Park300 is designed for 77W, this is actually even worse! Am I doing something wrong here? Or is eCalc's xcopterCalc not taking into account that there are 3 motors (am I being too simplistic, thinking that the electrical load is spread over the 3 motors?).

I am tempted to put them on and put it in a hover for a short time, then check the temp on the motors (if the thing gets off the ground at all). Do you see any risk in that (other than it tumbling down, for which reason I'll be hovering it over grass, only 3-6 feet high)?

 

[FinalGlideAus]

I've got the FT suggested Park300 1380kv on my Bat Bone and they work although I rarely go over half throttle since I'm still learning. With around 30 flights they're still working but they run rather hot and I'm not expecting them to last. I've got the NTM 28 1200kv motors coming so hopefully I can comment on the difference when I put them on early next week.

 

[Sammy]

Looking forward to see that review on the updated motors!

 

[FinalGlideAus]

The NTM 28 1200kv motors came a little earlier than expected so I was able to test them out today. I'm running Afro 20amp ESC's and zippy 2200 3s 30c batteries and 9by4.7 props with it and getting around 11 mintues flying (half hover, half circuits) with cut off at 11.1v as opposed to 9minutes with the Park 300's. Much more power than the Park 300's but still very nice to fly and not hard to handle. The only downside so far was I ordered four Ntm's to have one as a spare and two arrived with noisy bad bearings. I'll be heading to a bearing shop to replace all the bearings tomorrow hopefully. I know the Hobbyking stuff is cheap but that kind of thing pisses me off.

So aside from the bearings I'm really happy with the performance.

 

[Craftydan]

FGA,

At 11 min, Sounds like you're getting good use out of those motors.

What's your Weight up to? What prop?

 

[FinalGlideAus]

Haven't weighed it since I put the Ntm's on it but I'd say around 750grams. I have Gemfan 9 by 4.7 props on it. Only had a couple of flights but I was also impressed with the flight times. More testing after I flash my KK2.1 and get new bearings.

 

[FinalGlideAus]

I have new bearings now for my NTM's and they're much quieter and running very nice. Good Japanese ones cost me $4.95 AUS each. I also had to swap out a prop nut from my spare accessory pack because the thread was not tapped straight and the spinner wobbled and put the motor out of balance. I knew there was a reason for ordering spares...

 

[Gringo13]

Hi everyone, first time on any kind of forum and trying to get in to this hobby down south, Brazil. I typically have the same question as Sammy, but I wanted a motor not only for the bat bone but also for an RC airplane like the mustang, cruiser and might I also might make in the future a V-Tail quadcopter. I've had me eye on two NTM motors both 2826, one is 1000kv and other is 1200kv. Gonna be using a 3s 2200mah battery because of the cheap cost hoping I will get around 10min of flight time on the planes and tricopter. I'll try not to repeat any questions on the forum.

 

[trigger]

Hi everyone, first time on any kind of forum and trying to get in to this hobby down south, Brazil. I typically have the same question as Sammy, but I wanted a motor not only for the bat bone but also for an RC airplane like the mustang, cruiser and might I also might make in the future a V-Tail quadcopter. I've had me eye on two NTM motors both 2826, one is 1000kv and other is 1200kv. Gonna be using a 3s 2200mah battery because of the cheap cost hoping I will get around 10min of flight time on the planes and tricopter. I'll try not to repeat any questions on the forum.

Hi, welcome to Flite Test Forum

If you can, I'd suggest considering other brands for your motors. NTMs aren't the best ones around, and often suffer from bad bearings.
I've been using Sunnysky motors exclusively now, and they are much, much better than the first NTM set I bought. And they aren't much more expensive than the NTMs (remember that you have to buy the accessory pack with those, while it's included with the Sunnysky's)

There are other brands that are worth it, but I can't comment since I didn't use them first hand

 

[Gringo13]

That the problem, I've been looking at so many motor and dont know the reputation that they have. I've been basing my research on Flite Test and have seen the brand pop up quite a bit.

I have another question. lets say that I have a 1200kv motor on a multicopter(quad or tri) and lower it to around 700kv or 800kv using the same electronics and battery whould it become more efficient in flight time?

Trying to put the pieces together. =D

 

[Gringo13]

Ok, I've been looking around vids and sites and found buddyrc.com and found the sunnysky x2208 1260kv and the x2216 1100kv the x2208 i've seen being flown on tricopters with 8x4.5 props. do you think they will hold a 9x4.5 prop on an plane?

What is Park400?
Dificult to find questions in Brazil.