KDE Direct has added Multi-Rotor Heli motors to their lineup

[fltundra]

Manufactures certainly don't seem to make it easy to compare specifics, so confusing..

I don't know if I did the math correctly but on:

4S it takes .4827A per pound of thrust
6S it takes .5072A per pound of thrust

Seems like a fairly negligible difference. Is there any way to figure out approximate flight time from the information KDE provides on their data sheet?

I see a lot of people going with much lower KV motors and larger props resulting in longer flight times but it also appears to be less stable. I'd rather have a more stable MR with 10 minutes of flight time than trying to get 30 minutes of flight time. But its hard to figure out the best components, I don't trust eCalc.

Also, has anyone used these ESC's with the KDE 2814XF-515? http://www.quadframe.us/collections/motors-and-propellers/products/dys-esc-40a-simonk

Chuck,
If you are not going with the KDE esc's, go with the Castles, trust me. They work flawless with the SuperX and the KDE's.

 

[Av8Chuck]

Which Castle ESC's are you using?

 

[fltundra]

Which Castle ESC's are you using?

25 MR's

 

[SamaraMedia]

Manufactures certainly don't seem to make it easy to compare specifics, so confusing..

I don't know if I did the math correctly but on:

4S it takes .4827A per pound of thrust
6S it takes .5072A per pound of thrust

Seems like a fairly negligible difference. Is there any way to figure out approximate flight time from the information KDE provides on their data sheet?

I see a lot of people going with much lower KV motors and larger props resulting in longer flight times but it also appears to be less stable. I'd rather have a more stable MR with 10 minutes of flight time than trying to get 30 minutes of flight time. But its hard to figure out the best components, I don't trust eCalc.

Also, has anyone used these ESC's with the KDE 2814XF-515? http://www.quadframe.us/collections/motors-and-propellers/products/dys-esc-40a-simonk

Thanks for the calculations Chuck,

I have ZTW 45amp SimonK esc's on my hexa now, I'll let you know how they react with the KDE's once I'm up and running.

john

 

[LeeT]

Thanks for the calculations Chuck,

I have ZTW 45amp SimonK esc's on my hexa now, I'll let you know how they react with the KDE's once I'm up and running.

john

I have a 650 hex, KDE 2814 - 515kv motors, Castle 35 mr ESC. AUW is 3000 gms. Flying a 6000 4S mah Nano Tech battery I get 12 minutes of slow flight (AP only) with 80% discharge. Flying 13" Graupner, 650 is limited to 13" props, as 14" will hit each other. Very happy with flight time, as I was hoping for 10 based on ecalc calculations. Also happy with KDE motors, first purchase of a high quality motor. Very smooth and relatively quiet. Flying in 85 to 90 degree Florida heat and humidity motors and ESCs cool to the touch.

 

[Benjamin Rowland]

Been flying the Red a ton with the KDE 3520's and triple props. Low fast shots - it's a blast. These motors are great (paid full price, no paid endorsement here).

View attachment 19184

 

[SamaraMedia]

Is that a Vulcan frame Ben? What's your setup? Hex, octo, Hoverfly Pro, what gimbal?

Disregard, saw in your "Less is more" thread it is a Vulcan and Movi. Look forward to seeing some video of your new setup.

john

 

[sk8brd]

av8chuck, if you know your auw, you can reference the amp draw figures on the kde spec sheets for your prop size and voltage your using to predict hover time. take your auw in grams-to make it easy then divide by number of motors. this is the amount of thrust per motor you need to make your rig hover. reference the spec sheet for that thrust number per motor using the prop size and voltage your using and look at the amp draw. once you know how many amps per motor are being used to hover- multiply that number by the amount of motors on your rig to get overall total hover amp draw.
Then convert your batt mah to amp hours then divide by total amp draw and multiply by 60. this will give you hover time ballpark wise if the auw numbers are correct and spec numbers provided by kde are correct. if the spec sheets are not exact for your auw just use closest figures for ballpark numbers.

here is a theoretical example since i cannot explain things well.lol ..

Say my 450 on 6s w/ 11inch props (auw) is 2760 grams. i divide 2760 by 4 to get minimum thrust per gram i need to lift my craft, ends up to be 690 grams of thrust. 2760/4= 690.

i reference the kde spec sheet chart for 6s with the 11X3.7 prop that i'm using and it tells me i can lift 690 grams at 50% throttle at a 2.9 amp draw-*see 515kv spec sheet w/ 6s and 11prop.
take 2.9amps and multiply by number of motors which is 4 on my quad and that equals 11.6 amps for hover for my rig. 2.9*4=11.6
I'm using a 6s 5000mah batt so i convert to amp hours 5000mah becomes 5.0ah then divide by the total amp draw figure which was 11.6 and then multiply by 60...

what it looks like----5.0ah/11.6amps X 60=25.86 ish min-hover time .

* this is using 100% of the battery so multiply the hover time by .8 to use only 80% of the total mah to keep lipo happy which will give you 20.6ish hover time. this is hover time not flight time, can't predict how heavy on the throttle your going to be during flight, altitude, wind etc these can effect numbers as well as components that also use some mah but this will give you ballpark numbers and has worked for me making predictions on builds and comparing motors. The kde's are great, the computer balancing is a biggie for me as i'm only interested in the end raw video result, jello for me is a no no and the added efficiency and build quality of these motors is icing on the cake.

you can also find your amp draw for your flight if you don't have osd with telemetry by using flight time and mah used. simply take mah used convert to amp hour divide by flight time and multiply by 60- thats your total amp draw for your flight.

ex- my 450 used 4000mah and flew for 20.6 minutes. so 4.0/20.6* 60= 11.6 amps---

 

[fltundra]

4S it takes .4827A per pound of thrust
6S it takes .5072A per pound of thrust

Seems like a fairly negligible difference. Is there any way to figure out approximate flight time from the information KDE provides on their data sheet?

Chuck,
Your right, with the increase in voltage and efficiency it looks like i will gain a minute or two of flight time changing over to my 6S with 12x5.5's or 13x4.4's. My lipo's both have same per cell weight. Now to balance up some props. My AUW with the 4S is 2515g and with the 6S it's 2925g. Both are 8000mah, I'll post my findings.:tennis:

 

[Luc Maximilien]

Do not trust manufacturer data sheets .
They are all very "optimistic" .
Kde claims for the [FONT=Helvetica, Arial, sans-serif]2814-515 and 14" prop an incredible 15 gr/watt while in real world the real performance is 10 gr/watt as fltundra might confirm.

Flight time is mostly related to propeller and batteries , motor , if it has the right KV is not such relevant while it is essential for reliability .

In my 7 years experience I would not say that stability is related to high Kv motors (obviously setting right Pid ) .
High Kv motors is a choice that reduce prop diameter (and once there were simply no large and light propellers for multirotors) and also help a lot to reduce vibrations because it is easier to reduce high frequency vibrations rather than low ones.

I do not trust eCalc while I trust my bench

Anyway as a rule of thumb with an hexa and props until 16" and AWU of 3000 gr you'll have 11 gr / watt at best , 9 gr /watt as mediocre , under 8 gr / watt you are in the bad side of efficiency.

If you know how many grams / watt gives your motor/prop it will be easy to calculate flight time :
(Ampere of battery * tension * 60) / (weight / gr per watt)

so i.e. if you have a 5A 4S battery , 2500 gr AUW and a 10 gr / watt motor/prop :
(5 * 14,8 * 60 ) / (2500 / 10) = 4440 /250 = 17,76 minutes

Want to mount a 6600 4S battery that weights 200 grams more , your efficiency will drop a little so 9,7 gr / watt:
[FONT=Helvetica, Arial, sans-serif](6,6 * 14,8 * 60 ) / (2700 / 9,7) = 5860 /278,3 = 21,0 minutes[/FONT]
[/FONT]

 

[Av8Chuck]

How do you determine the gr/watt?

 

[Luc Maximilien]

You can calculate gr/watt by measuring amperes and tension while hovering without wind .
Watt = Ampere * volts
You can use a datalogger or telemetry if your radio/receiver or more simply this Watt meter from HK

When you have Watts simply divide AUW by watt amount.
Or you can choose to trust "optimistic" values of manufacturers

 

[Av8Chuck]

You can calculate gr/watt by measuring amperes and tension while hovering without wind .
Watt = Ampere * volts
You can use a datalogger or telemetry if your radio/receiver or more simply this Watt meter from HK

When you have Watts simply divide AUW by watt amount.
Or you can choose to trust "optimistic" values of manufacturers

I think skepticism is a healthy thing. Even if the manufacturers values are correct knowing how to test this sort of thing is probably very helpful in developing good MR's. I've heard from a couple of people that the values KDE publishes are reasonably close. Are their variables that would explain any potential difference?

 

[kloner]

to the best of my knowledge these guys setup scales and power supplies. so, when you crank these things full throttle there is zero voltage sag, however when we setup in real life, we get a volt drop out of the gate and it goes straight to 22 volts pretty quick... There doesn't seem to be a qualified dyno they all base there stats on......

The biggest problem i see in all motors is the inconsistencies in each piece whether it's a bearing, balance, whatever. as soon as one of them is in play the numbers change really fast,,,, like crash fast

 

[Luc Maximilien]

I think skepticism is a healthy thing. Even if the manufacturers values are correct knowing how to test this sort of thing is probably very helpful in developing good MR's. I've heard from a couple of people that the values KDE publishes are reasonably close. Are their variables that would explain any potential difference?

Well with KDE2814XF-515 the claimed performance is very very far from reality , they claim 15 gr/W while an owner of that motor here in the forum got only 10 gr/watt with the same prop.
So far I have a quite bad opinion about KDE datas.
In fact claiming that a 85 grams motor with a 14" prop is delivering 15 gr/watt is like claiming that a car makes 200 miles with a gallon
Usually bench test gives a 10% more efficiency compared to real world.
The point is that several manufacturers use performances data sheets for marketing purposes...

 

[Luc Maximilien]

to the best of my knowledge these guys setup scales and power supplies. so, when you crank these things full throttle there is zero voltage sag, however when we setup in real life, we get a volt drop out of the gate and it goes straight to 22 volts pretty quick... There doesn't seem to be a qualified dyno they all base there stats on......

The biggest problem i see in all motors is the inconsistencies in each piece whether it's a bearing, balance, whatever. as soon as one of them is in play the numbers change really fast,,,, like crash fast

Voltage drop is not a problem if you work with Watts , when voltage drops , Ampere rise to keep the same thrust , watts remains the same.
This is also the reason why data sheets consider 14,8 or 15 volts for 4S, an average voltage during a flight.
Quality control if of course what makes the price difference .
Very often I have notice that budget motors do not have the KV they should and that might be a real problem later for finding the right propeller.

 

[Motopreserve]

Well with KDE2814XF-515 the claimed performance is very very far from reality , they claim 15 gr/W while an owner of that motor here in the forum got only 10 gr/watt with the same prop.
So far I have a quite bad opinion about KDE datas.
In fact claiming that a 85 grams motor with a 14" prop is delivering 15 gr/watt is like claiming that a car makes 200 miles with a gallon
Usually bench test gives a 10% more efficiency compared to real world.
The point is that several manufacturers use performances data sheets for marketing purposes...

Have you contacted them to get a clarification?

 

[Luc Maximilien]

Yes I did .
They were very kind , they confirm the 15 gr/watt but did not gave a real explanation when I told them that an owner reported 10 gr/watt with the same propeller of their datasheet.
BTW 10 gr/watt is a fair result for a 85 gram motor and a 14" prop, T-motor equivalent motor gave more or less the same result.
15 gr / watt is something incredible.

 

[Motopreserve]

Assuming it could be effected by the variables in different test setups? I know I've never gotten same results as posted on my cheesy thrust tester.

I'll be getting some of these motors soon - should be here this week. I'll be checking them on said tester before the install - but just for my own curiosity. Wouldn't post data here to influence a decision. It's not that good a tester.

 

[Av8Chuck]

I'm not interested in getting the latest and greatest, I'd like to be able to build different sized MR's for different kinds of payloads and have a better understanding of prop and motor combinations that yields more consistent results. Whatever a particular manufacturers methodology is for determining their data as long as they're consistent across their entire product line I can live with that.

I've heard very good things about the KDE MR motors so I'm certainly going to give them a try. I'd be interested in hearing your thoughts after the test.