Help needed choosing components a cheaper way that trial and error!

[Dan-27]

Hello. I'm fairly new to the hobby and I'm having a nightmare with the drive systems.

I could really use some advise with a couple of questions I've got, having burnt out 4 motors and 3 ESCs in the last month!

I assume that once experienced its easy to choose suitable prop / motor combos but after trawling the internet I can't find any easy way of working it out. For example I've just built my second versa wing, a blunt nose, yesterday I converted it into a tractor style plane and put what I thought was a suitable motor the front, a chunky 35mm 1400kv out runner. It didn't have enough grunt with the 8 x 4 prop so I put a 10 x 4.5 on at which point I cooked the ESC.

I've just bought a NTM Prop Drive Series 2826 1000kv motor and a 30A ESC for it, hoping that'll be enough.

Next question, how do you bench test without trashing more components? I had an ESC I wasn't sure about as I knew the motor had died in the crash, I plugged in a new park300 and it fried the motor. With this blunt nose ESC issue should I bench test the motor with a working ESC or cut my losses and scrap both motor and ESC? Also without bench testing what am I looking for to determine if the brushless motor is dead?

How on earth do you drill out props to fit on the motor shaft?

Lastly the park300 was the recommended motor for the FT flyer, I bought it and took ages to work out how to use the prop saver, but I couldn't get the prop to remain centralised. I bought a pack of adapters, but none fitted. Thankfully I have access to a metal lathe and was able to turn myself some that worked. Am I doing something wrong? I've yet to land with a conventional prop fitting without it breaking so would like to use a prop saver wherever possible.

Here's part of the death toll from last months flying!!



I really enjoy flying, but seem to spend most of my time in a cloud of white smoke rather than in the clouds! Help with any of the above questions would be much appreciated.

Dan

 

[Ron B]

before you buy your next motor see what the max size prop it can handle. Make sure it will handle the weight of the plane you want to fly and use the 100 watts per 16 oz rule. then make sure you get an esc that is well above the motors maximum draw (If it is 12 amp use a 20 or even a 30 amp esc as an example). make sure there is no possible short in the hookups you make.
I hope this helps.

 

[TEAJR66]

The prop saver has two sides. Sometimes if the prop wont center, turning the prop saver around can help.

I use a pair of scissors to open up the hole in the prop. The trick is to avoid altering the precision portion of the prop. Where the porp adapters fit into the prop should not be changed. Just the center, meaty part of the prop. Once it fits on the shaft, make sure you take it off and balance it. If you take to much meat out of the center, you could compromise the props structural integrity. Be careful.

The 10x4.5 prop was too much for that particular ESC. Check prop data on the motor when you buy it. Make sure the ESC is big enough for the amp draw. Make sure the motor can spin the prop on the number of cells you are using.

A watt meter is invaluable for non-destructive bench testing. That and knowing the ratings of the individual pieces. I have a 35mm motor that I thought would be a beast, turns out it is just a big pussy cat.

Specs:
Model: NTM Prop Drive Series 2826 1000kv
Kv: 1000rpm/v
Poles: 3
Motor Wind: 19T
Max current: 15A
Max Power: 176W @ 11.1V (3S) / 235W @ 15V (4S)
Weight: 54g
ESC: 20~30A
Cell count: 3s~4s Lipoly
Bolt holes: 16mm & 19mm
Bolt thread: M3
Connection: 3.5mm Bullet-connector

Prop Test Data:
9x4.7 - 11.1V / 113W / 10.2A / 0.632kg thrust
9x6 - 14.8V / 220W / 14.9A / 0.937kg thrust

That 8x4 prop should be good on that motor with a 4S battery. With a watt meter you will be able to tell if you are getting close to your max current.

Most planes come with a power setup recommendation. I try to stick with that initially. Once I have that plane sorted, I might play with different power set ups.

Ron B's advice for 100 watts per pound is pretty solid. Know your all up weight. It will help you make wiser decisions.

Be safe and have fun,
Tommy

 

[TEAJR66]

http://flitetest.com/articles/using-a-watt-meter

http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=34137

 

[Dakota_Kid]

For starters, we need more details on your equipment combinations.
Post some links to your motors, speed controllers, and propellers.
Which 35mm 1400 kv motor. What battery are you using.
2s, 3s, and what c rating is it? That makes a difference as well.

Your 2836 1000 kv motor specs were posted above. It states that a 9/4.7 prop will draw
10.2 amps which is 113 watts. It needs roughly a 10 amps x 1.5 safety margin for a speed controller
which puts that at around 15 amps. You can put a 20 or 30 on it but that just makes the plane heavier.
At 113 watts figure out how heavy of an airplane you can use it with.

As stated 100 watts / lb on airplanes, you should be able to fly a 18 oz airplane.
113/100 * 16 gives you 18 oz.
At 75 watts / lb, it can be a little heavier, like 21 oz.

You could use the new motor on the versawing. It can be light and float or have a bigger motor
and battery and fly faster as well. If your new and learning, I would suggest the lighter the better
and go slower. Even the Old Fogey seems more of a trainer to me. Easier to see with more profile.
Use the suggested motor speed controller prop combinations on the plans.

Here is an article on this site on choosing a power system.
It states:
Good rule of thumb: You need 75-100 Watts per pound for a trainer, 150W per pound for pattern or warbirds and 200W+ per pound for 3D and EDF Jets.

http://flitetest.com/articles/beginner-series-power-system

I flew a FT Versa Wing with a 2809 1400kv motor and a APC 7/4 prop on a 3s 1300ma 25c battery and it scoots
around just fine. That motor is rated 104 watts and I had 110 max wats on the bench. It flies at 1/3-1/2 throttle.

Next Question, How to Bench Test. Like stated before, get a watt meter.
Before doing that, look at the voltage, amp, watt, and recommend prop sizes for the motor on the
web page or manual so you have a recommended starting point.

The motor will try and turn it's kv rating x voltage no mater what prop you put on it.
Without a watt meter, starting low and working our way up is recommended. Mount the motor to something solid, put the recommended prop on, and run it for a bit. Unplug the battery and feel if it or the speed controller is getting hot. Then try longer run times and see if it is getting hot. Unplug the battery and check again. (Be Safe)

If you got a new 30 amp esc, use it with the new motor on the blunt. Stick with a 9/4.7 or 8/5 prop.
That should be plenty of thrust with a 3 cell battery. Since your under the 176 max watt rating on 3s, I would bet you could go up to 10/4 with that motor.

You can use the 30 amp esc to test the 300 motor and if the motor is good, then you can test the older esc's on that motor with a prop that won't exceed the current of either of them or no prop. If the esc don't work on the 300 motor after testing it with the new 30a esc, then it is probably junk.

To see if a motor is bad, look at the wiring and take off the outside stator if you can. Look at the windings and see if anything is burnt. You can cut the heat shrink off the esc and check the same way. Or hook them up and see if it works without a prop on the motor before taking them apart.

To drill out the prop, use a prop reamer. It is supposed to keep it centered so it doesn't get out of balance.
I buy APC props that have adapters with them for 6 sizes of prop shafts.
I see one of your motors has a prop saver, You should be able to find one of the adapters that centers the prop on the hub.

I use a Collet style adapter for most of my prop applications.
I use the adapter with the correct size to center it on the shaft and tighten the nut.


That is a HobbyKing Tower Pro 2809 1400 kv motor and 7/4 prop used on my versa wing and a new trainer that I made
using the same power pod.
A few pics here.
http://forum.flitetest.com/showthread.php?11181-New-Trainer-Swappable


As far as breaking off props, I put a nose wheel on the back side of the motor firewall. I made a delta wing and without a prop saver, and I broke a prop at least 50% of the landings.
A piece of wire bent back a bit would do the same thing.




Hope this helps. Get us more info if you need more help.

 

[RAM]

Also agree that a wattmeter would be a good addition to your kit. This way you can test different configurations and be sure you are not going to exceed the specs.

 

[Dan-27]

Thanks to everyone who contributed. I tried to fly with blunt nose with the new motor and an 8x4 prop but couldn't manage anything more than a glide to the ground, so I've ordered some 9x5's. Should have it in the air shortly!

 

[Echo9]

Fellow nube here.
I try to stick with the FT recommended electronics.
Like the Suppo matching motors and 18A, 20A or 30A ESC
Avoid 2 cell lipo and high C rating.
Stick with 20C to avoid cooking your ESC while you learn.
Try to turn the motor brake on, may save your prop more times than not

A 1300 mAH 20 C puts out approx 26 amps. 1600 20 C puts out 32 amps (normal not max rating)

Some examples - no meter involved just math
Motor WATTS BATVOLTS DRAWAMPS
Suppo 2208/17 100 11.1 9.01
Suppo 2208/14 130 7.4 17.57 motor draw amps much higher with 2 cell
Suppo 2208/14 130 11.1 11.71
Suppo 2212/15 130 11.1 11.71


Recommended electronics: Versa published at the FT store in the build kit description

Versa Weight - 10.6 oz (300 g) without battery

Complete Electronics Kit - Swappable Power/Electronics "The Beef"
MOTOR (Option 1) - "THE BEEF" (Motor only) GT2215/09 70g
MOTOR (Option 2) - Suppo 2208/14 1450kv Brushless Motor (Park 370 equiv.)
MOTOR (Option 3) - "Blue Wonder" 2712-12 24g

Servos (Option 1) - Hextronic 9 Gram Servo
Servos (Option 2) - Suppo SP-90 9g Micro Servo

ESC (Option 1) - TURNIGY Plush 25amp Speed Controller
ESC (Option 2) - Suppo 18A Brushless ESC

Battery (Option 1) - Turnigy 1000mAh 3s 20C Lipo Pack
Battery (Option 2) - Turnigy 1800mAh 3s 20C Lipo Pack
Battery (Option 3) - Turnigy 2200mAh 3s 20C Lipo Pack

Note pusher and tractor prop difference
Prop (tractor) - Slow Fly 10x4.7 prop
Prop (pusher) - APC Style 8x6 prop

I too need to weigh my planes for proper motor/prop sizing- postal scale is on my wish list

Good Luck!

 

[Echo9]

This video may help you. Basically states when you blow the ESC, probably damaged the motor, viscous circle,as the motor may blow then replacement ESC. It's over my head... bottom line for me is when I fry an ESC, I put the motor aside too.

RC Model Reviews
https://www.youtube.com/watch?v=9YO1IbQQ1w4&list=UUahqHsTaADV8MMmj2D5i1Vw