Hello, I just got a powermeter because I wanted to know how much power I am drawing from the battery. So now comes the question: can I use any size prop as long as the parameters stay within reasonable limits? And also why have heard that it is bad for the motor to spin without a propeller? I checked and it only generated like 2w.
Can I use any propeller i want as long the amperage and wattage stays within the limits?
- Thread starter Superman
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quorneng
Master member
I assume you have a brushless motor. They are a constant speed type dependent on the voltage applied and the number of turns in the winding. They thus will not over speed provided the applied voltage is within the motor' s specification.
The fact they are a constant speed type means they will try to run at their design speed regardless of the load. Too big a prop and the motor will try to draw as many amps as it needs. Exceed the specified maximum amps for more than a few seconds and the motor will over heat which can easily ruin it.
So use you power meter wisely.
If you see the amps rising towards the motor's rated maximum as you open the throttle - stop and fit a smaller prop.
Remember both the speed controller (ESC) and the battery have maximum amp limits too. The ESC in particular will over heat very fast indeed if over loaded and will fail terminally!
The fact they are a constant speed type means they will try to run at their design speed regardless of the load. Too big a prop and the motor will try to draw as many amps as it needs. Exceed the specified maximum amps for more than a few seconds and the motor will over heat which can easily ruin it.
So use you power meter wisely.
If you see the amps rising towards the motor's rated maximum as you open the throttle - stop and fit a smaller prop. Remember both the speed controller (ESC) and the battery have maximum amp limits too. The ESC in particular will over heat very fast indeed if over loaded and will fail terminally!
Yes, you can use any prop that doesn’t draw too many watts. A watt meter is a great tool but, sometimes stuff is overrated. You also need to check the motor, ESC and battery for overheating.
Start with a 10 second run at full throttle, stop and check the temperatures by touching the motor, esc and battery. Warm is OK, but if it is so hot you can’t hold for a few seconds, STOP, that’s too hot, the prop is too large. If if passes, try a 30 second run, then a 60 second run. Then if it passes, go for a fly. Keep in mind that a prop that worked when it was 70F degrees may cause overheating when it’s 95F outside.
When you land it’s good practice to periodically check the temperatures.
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ProfessorFate
Active member
Right now my power system for 3-4# planes is
3s 2.6 ah lipo
40-65 amp controllers at least a 5 amp bec
4008 (40x8mm stator) 850kv
wye wound series parallel 19ga 28 amps
Mfrs deltas pull 40 amps same setup
12x8 apc wot 30 amps 62 oz thrust
I want to also try the idea of propping up
With a 13x8 and 14x8.5
Avoiding programming a throttle limit, first running with eagle tree watt meter I'll set the trim tab see if that holds it to the motors' current limit or close like 30 amps.
It might just work good on the 13.
Planes power system unloads moving in air, static ground testing always uses more power.
Program throttle limit when the trim won't work. I just wouldn't get too big if you already know you hit the current limit wot like me with a 12x8.
The efficiency trade off, larger prop with lower rpms VS smaller prop higher rpms less load, is something we should try.
Could we get more thrust using less power by lowering rpms on a larger prop with pre-set throttle limits?
See on this 2814 test chart, the differences in half pound increments, how thrust cost more in watts, as rpm increases...it's not linear.
The GWS 12x8 uses a lot less power and delivers more thrust at lower rpms.
50mph coincides with 50 oz thrust at about 6000 rpms.
GWS isn't made anymore but I still have some, APC are much more durable but take more rpms and power to do the same job.
The handwritten apc 12x8 chart is data APC.
3s 2.6 ah lipo
40-65 amp controllers at least a 5 amp bec
4008 (40x8mm stator) 850kv
wye wound series parallel 19ga 28 amps
Mfrs deltas pull 40 amps same setup
12x8 apc wot 30 amps 62 oz thrust
I want to also try the idea of propping up
With a 13x8 and 14x8.5
Avoiding programming a throttle limit, first running with eagle tree watt meter I'll set the trim tab see if that holds it to the motors' current limit or close like 30 amps.
It might just work good on the 13.
Planes power system unloads moving in air, static ground testing always uses more power.
Program throttle limit when the trim won't work. I just wouldn't get too big if you already know you hit the current limit wot like me with a 12x8.
The efficiency trade off, larger prop with lower rpms VS smaller prop higher rpms less load, is something we should try.
Could we get more thrust using less power by lowering rpms on a larger prop with pre-set throttle limits?
See on this 2814 test chart, the differences in half pound increments, how thrust cost more in watts, as rpm increases...it's not linear.
The GWS 12x8 uses a lot less power and delivers more thrust at lower rpms.
50mph coincides with 50 oz thrust at about 6000 rpms.
GWS isn't made anymore but I still have some, APC are much more durable but take more rpms and power to do the same job.
The handwritten apc 12x8 chart is data APC.
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ProfessorFate
Active member
Hi Superman
I just tried a 13x8 with lowest throttle trim, steady wot 36 amps and bursts hit 40 amps.
But also using stick management, right about there almost at the top is OK, 30 amps.
I could fly with the 13x8 apc and not burn the motor.
Ok, now I just tried the 14x8.5 and wot pulled 45 amps, and throttle stick like in picture 30 amps.
This could also work, and with all today's testing I used a 4s life that's 1v more than 3s lipos.
Definitely will work with my lipos and they're 7 oz, the lithium iron are13 oz. Both will be good.
Motor is 850kv
Here's my test airplane, a wood version of the Zlin Savage Bobber.
I just tried a 13x8 with lowest throttle trim, steady wot 36 amps and bursts hit 40 amps.
But also using stick management, right about there almost at the top is OK, 30 amps.
I could fly with the 13x8 apc and not burn the motor.
Ok, now I just tried the 14x8.5 and wot pulled 45 amps, and throttle stick like in picture 30 amps.
This could also work, and with all today's testing I used a 4s life that's 1v more than 3s lipos.
Definitely will work with my lipos and they're 7 oz, the lithium iron are13 oz. Both will be good.
Motor is 850kv
Here's my test airplane, a wood version of the Zlin Savage Bobber.
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ProfessorFate
Active member
Superman, you never told us what's your power system motor by stator size, kv, motor controller and amps rating, battery, prop in range and props wanting to try.
Can you post these?
Can you post these?
Sorry that I am replying so late. I have this motor https://hobbyking.com/en_us/turnigy-aerodrive-sk3-3530-1150kv-brushless-outrunner-motor.html. 40 amp ESC 2200mah 25C 3S lipo. I would like to try to put on propellers ranging from 8x6 -10x6 and everything between
hankflies03
Active member
that should work perfect for 3S. I would use a 9x4.5 or somewhere around there
mastermalpass
Elite member
10x6 might be in the higher end of the 1000kv limits. I'm not sure - FT use a 10x4.5 2-Blade for the Spit; closest I have is an 11x7 Master Airscrew 3-Blade. My 1000kv motor made an odd smell on the test bed spinning that one, so got something around 780kv for it instead.
ProfessorFate
Active member
Hi yall
Look at innov8tivedesigns.com badass motor performance charts, see how different motors spin 12 n 13" apc props.
Few weeks ago I wound an iflight 3508q 1200kv 20ga limit 22amps works great 8 to 10 inch props good thrust. Wye motor uses 25% less power, but just found out larger like HUGE motors also use much less energy to do same job.
Your motor is 76g, mine is 145g or 5oz given wye termination and larger size stator is 35mm x 8mm deep. I think this strikes the right balance between real small and too large. I fly my Storch with the 4008.
The wye motors really give an edge on power, I've got a good size. Thinking I want to also build a Spitfire maybe scale up little to 48" use this motor with a 10" prop 3s 2.6ah lipo n 40a esc.
I just happen to buy a bunch of these larger batteries and want to build for the hardware I already have. My 2 goto motors...new discovery....are 4008 850kv for 13x8s 4# thrust and 3508s for prop jets 8 to 10" 1200kv for a 48" spitfire
I've got to do more testing on my 4008 motors somehow I think I got more thrust for less power with an apc 13x8 than with a 12x8 because it reduced rpms maybe each prop has slightly different profile or pattern besides just a difference in size.
Here's my hpdlrk adjacent coil wind I made last year. Manual and Trug came up with original adj wind and I improved it by an even distribution of conflicting fat and skinny coils. Always wind odds first n cram the evens in afterwards and take whatever you can get. It gets tight and I like to get maximum copper fill. Get one of both these motors and wind them. You'll like it. Circles are counterclockwise. Butt of arrow is first, arrow tip is 2nd.
You can write the pattern simple like on my desk, Y bundle odds.
If you have a motor with high enough kv it could overheat then in addition to trimming throttle low, you could set up a sub trim for the specific model where you've decided on a large prop like I have. 13x8 with my 850kv just need to stay off top 2 clicks on stick. Smaller 3508s using 10" might be same but it's close to 1300kv, have to see what top end compensation is needed after further testing.
Look at innov8tivedesigns.com badass motor performance charts, see how different motors spin 12 n 13" apc props.
Few weeks ago I wound an iflight 3508q 1200kv 20ga limit 22amps works great 8 to 10 inch props good thrust. Wye motor uses 25% less power, but just found out larger like HUGE motors also use much less energy to do same job.
Your motor is 76g, mine is 145g or 5oz given wye termination and larger size stator is 35mm x 8mm deep. I think this strikes the right balance between real small and too large. I fly my Storch with the 4008.
The wye motors really give an edge on power, I've got a good size. Thinking I want to also build a Spitfire maybe scale up little to 48" use this motor with a 10" prop 3s 2.6ah lipo n 40a esc.
I just happen to buy a bunch of these larger batteries and want to build for the hardware I already have. My 2 goto motors...new discovery....are 4008 850kv for 13x8s 4# thrust and 3508s for prop jets 8 to 10" 1200kv for a 48" spitfire
I've got to do more testing on my 4008 motors somehow I think I got more thrust for less power with an apc 13x8 than with a 12x8 because it reduced rpms maybe each prop has slightly different profile or pattern besides just a difference in size.
Here's my hpdlrk adjacent coil wind I made last year. Manual and Trug came up with original adj wind and I improved it by an even distribution of conflicting fat and skinny coils. Always wind odds first n cram the evens in afterwards and take whatever you can get. It gets tight and I like to get maximum copper fill. Get one of both these motors and wind them. You'll like it. Circles are counterclockwise. Butt of arrow is first, arrow tip is 2nd.
You can write the pattern simple like on my desk, Y bundle odds.
If you have a motor with high enough kv it could overheat then in addition to trimming throttle low, you could set up a sub trim for the specific model where you've decided on a large prop like I have. 13x8 with my 850kv just need to stay off top 2 clicks on stick. Smaller 3508s using 10" might be same but it's close to 1300kv, have to see what top end compensation is needed after further testing.
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mastermalpass
Elite member
Wait, when you say you're winding a motor, do you mean you're essentially making your own motor as far as choosing the grade of copper wire and how many loops go on each coil? That's pretty cool if you can get kits for such projects!
Also, are you sure you have the right site there? I visited innov8ivedesigns.com and it's all about welding and metal fabrication.
ProfessorFate
Active member
good morning
Got wrong site, search innov8tivedesigns.com and brushless motors, that should get you there.
I started buying some 2215 and 2212 scorpion kits on sale. We discuss/list motors by their stator size mostly. Later bought some pancake motors from iflight. Pancake motors are easy to find. Bought 6 badass 2820 but they're turning out hard to wind.
Pancake motors are most forgiving, leaving base attached on bearing tube is how I wind it. The closed case type conventional outrunner is very hard to remove stator from bearing tube to wind. The 4008 pancake is the very best motor to wind, at least starting out. Just buy a pancake motor, unwind counting turns per head.
But you might just do your own test wind.
You already have my test hpdlrk wye test, 12t for 1005kv.
get the turn calculator. It's on rcgroups, see that title page, it has a bunch of links to helpful stuff
Best wire and good price TechFixx.com they link you to buy at eBay. Best sizes to get for this power range motor size, 18, 19, 20, and some 21 or 22ga for test winds
I'm finding it hard getting a good wind with larger wire or multistrand on closed case motors. Been trying several times to separate the badass 2820 stator from tube heat, freezing, penetrants.
Always try ending wind inside so you don't have to glue the loose hanging wire to the stator.
Do a test wind, here's last motor 4008 wind where I got the largest gage wire in two layers wound. HPDLRK terminated wye is what I find best. Manuel's turn calculator needs input on spreadsheet as either dLRK delta or wye. I didn't use the turn calculator.
After a test, I multiply kv x turns, getting a product number associated. Mine was 14 turns.
Divide the product by another number of turns and see the kv prediction. My test was more accurate being wound with heavier 23 gage wire, and closer turns value to the kv I wanted.
I missed turns and the average was12, so if I wind a 4008 again wanting 18ga for that 32 amp limit I'll go for an even 12 turns with no missed turns and try compressing top with a harder wood or steel plate and epoxy bottom of coils holding position. As is just wound, the rotor clearance is too tight or would scrape the coils and short the motor
Got wrong site, search innov8tivedesigns.com and brushless motors, that should get you there.
I started buying some 2215 and 2212 scorpion kits on sale. We discuss/list motors by their stator size mostly. Later bought some pancake motors from iflight. Pancake motors are easy to find. Bought 6 badass 2820 but they're turning out hard to wind.
Pancake motors are most forgiving, leaving base attached on bearing tube is how I wind it. The closed case type conventional outrunner is very hard to remove stator from bearing tube to wind. The 4008 pancake is the very best motor to wind, at least starting out. Just buy a pancake motor, unwind counting turns per head.
But you might just do your own test wind.
You already have my test hpdlrk wye test, 12t for 1005kv.
get the turn calculator. It's on rcgroups, see that title page, it has a bunch of links to helpful stuff
Best wire and good price TechFixx.com they link you to buy at eBay. Best sizes to get for this power range motor size, 18, 19, 20, and some 21 or 22ga for test winds
I'm finding it hard getting a good wind with larger wire or multistrand on closed case motors. Been trying several times to separate the badass 2820 stator from tube heat, freezing, penetrants.
Always try ending wind inside so you don't have to glue the loose hanging wire to the stator.
Do a test wind, here's last motor 4008 wind where I got the largest gage wire in two layers wound. HPDLRK terminated wye is what I find best. Manuel's turn calculator needs input on spreadsheet as either dLRK delta or wye. I didn't use the turn calculator.
After a test, I multiply kv x turns, getting a product number associated. Mine was 14 turns.
Divide the product by another number of turns and see the kv prediction. My test was more accurate being wound with heavier 23 gage wire, and closer turns value to the kv I wanted.
I missed turns and the average was12, so if I wind a 4008 again wanting 18ga for that 32 amp limit I'll go for an even 12 turns with no missed turns and try compressing top with a harder wood or steel plate and epoxy bottom of coils holding position. As is just wound, the rotor clearance is too tight or would scrape the coils and short the motor
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mastermalpass
Elite member
Pretty damn awesome. I do like the idea of being able to assemble my own motor, tailored to a certain prop for the most optimum [Insert flying style] performance!
ProfessorFate
Active member
I should correct some things, maybe I got carried away before I knew...
4008 multirotor motors weigh 6.261 oz with long 12ga leads and 3.5mm connectors.
There's a larger mfrs standard delta motor BA 3520-720 weighs 8oz, see 3s 12x8.
See it does as good power wise with a 12x8 BUT what size prop would you really use on an 8 oz motor? 14 or 15 inch for heavier models.
I'm trying to figure a light system like FliteTest people would use for the spitfire
BEEF 2217-950kv 10x6 or 9x6 prop at 2.22oz, Phoenix 45 controller 1.77oz, 2.6ah lipo 7.3oz
4008 multirotor motors weigh 6.261 oz with long 12ga leads and 3.5mm connectors.
There's a larger mfrs standard delta motor BA 3520-720 weighs 8oz, see 3s 12x8.
See it does as good power wise with a 12x8 BUT what size prop would you really use on an 8 oz motor? 14 or 15 inch for heavier models.
I'm trying to figure a light system like FliteTest people would use for the spitfire
BEEF 2217-950kv 10x6 or 9x6 prop at 2.22oz, Phoenix 45 controller 1.77oz, 2.6ah lipo 7.3oz
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