300X - The Weight Watchers Tread

[SHYguy]

http://www.hobbyking.com/hobbyking/s...dProduct=21975


Looks very similar to the Wicked, Parkfly on the left, Wicked on the right. I dremeled a flat field on the shaft. It came with no extras - no connectors or pinions.


Weight is also exactly the same, 54.3 grams with wires and connectors.

[sharicasmi]

Isn't the parkfly 3600kv and the wicked 4800kv? That would mean you'd be running like a 9t on dons wicked and a 11/12t on the HK motor. Or am i mistaken?

[SHYguy]

10/136 and 100% was great on the Wicked, as long as it lasted (not very long).

10/136 was too little for the Parkfly, I'll try 11/136.

So even if they are physically equal I guess they are wound differently.

EDIT: 11T on the Parkfly 2632 was perfect! Flew just as well as the Wicked on a 10T - this must be THE best bang for the buck upgrade for the 300X!

[SHYguy]

10.2 vs 4.2 grams = 6 grams heavier

(the other bearing for the plastic tail case is under the case :-)

[SHYguy]

My precious carbon boom finally died, so this was a good time to check weight.

Indeed 5 grams lighter Steve.

[SHYguy]

Weight:

• Stock woodies 36 grams

• Blade carbon blades (balanced) 32.5 grams (3.5 grams lighter than wood)

• SAB 255 carbon blades (not balanced) 31.6 grams (0.9 grams lighter vs B-CF)

• EDGE 253 carbon blades (not balanced) 30.9 grams (1.6 grams lighter vs B-CF)

[SHYguy]

Been busy lately, but got to test this... amazing!!!

The heli feels so much more nimble, tic-tocs are a lot easier!

I used the Nano-Tech 850 mAh batt.

I'll be back with exact weight etc. Wires are A LOT thinner too, but worked just fine!

Wanted to test vs a 1500 mAh batt too, but the one I got is defective regrettably.

Downside is only 2:30 flight time with Parkfly 2632 motor. But it sure does showcase the potential of a lighter heli!

[stevebaker]

...and screws up the CoG

The 1500 is much better suited for this heli - you just up the headspeed a little to more than compensate for the extra weight.

[jcmo]

I'm reporting in here from my 300x supersport build, and I've been watching my weight. Watching it climb with every upgrade part I put on this little pig. I think it's nearly 100g heavier than stock now, but I haven't shortened the servo wires yet. I've got 21g servos on all the cyclics, I think I should probably go down to something smaller if it can handle the load. Probably the HiTecs. Just going middle of the road with those saves a whole servo worth of weight.

SHYGuy - Have you tested with any Scorpion motor? I know lots of people like them, not sure if the weight/power tradeoff makes sense.

[SHYguy]

Yeah I got the Scorp, but have not had the time to put it on yet... plus YEP30, Lynx OWB... soon!

Sadly the 1500 pack I ordered for test was a dud

[SHYguy]

61.3 grams vs. the Parkfly at 54.4 grams = 6.9 grams heavier

[jcmo]

I wish I had paid more attention to my physics classes... I wonder how much more lift can be generated by the higher HS possible with larger pinions on the Scorpion motor. In other words, what effect does the Scorpion have on the power/weight ratio? How much more headspeed can you get comfortably? Does a 10% HS boost equal more than 7g extra lift, or more? I don't even know what equations to use to calculate. I forgot how to math.

Just looking at it, it seems like they're pushing the dimensions of what will fit under the canopy

[JMHoffman]

Originally Posted by jcmo

Does a 10% HS boost equal more than 7g extra lift, or more? I don't even know what equations to use to calculate. I forgot how to math.

Such a simple question, such a difficult answer.

As a guideline, lift goes up with the power of the motor, not just with HS. And lift goes up roughly with the cube root of the square of the power, which is to say, with the power^(2/3).

Or --- still as a very rough guideline --- if you triple the power of the motor you double the lift.

Best way to determine lift is empirically with a scale. Put the heli on a scale. The difference between the weight with no blade motion and the weight with full HS and full negative pitch is a pretty accurate indication of the lift. (Make sure your skids are up to this.)

[jcmo]

Originally Posted by JMHoffman

...as a very rough guideline --- if you triple the power of the motor you double the lift.

OK, that's good insight, I appreciate your input. That leads me to a couple more questions to help me quantify what we're talking about here a bit better. Is this "Power" as expressed in watts? Torque?

As I look over the specs of each motor, the P2632, the Wicked 4800kv, and the Scorpion HKII-2213-14 the Wattage doesn't tell much of a story. There's not much else I know how to compare given the way the stats are listed differently between the manufacturers. They're all rated, depending on the application, in the neighborhood of 330W. We all know how much "ratings" mean when it comes down to real world application. What do we look at next then, winding pattern, stator arms, that sort of thing?

[SHYguy]

This is not so easy. The way it's wound etc will kinda result in the motor's "internal gearing". Then specs is one thing... real life test something else.

The Wicked and Parkfly differ. The Wicked is great on a 10T. While the Parkfly must have an 11T in order to give more HS vs. the stock motor on 9T.

[JMHoffman]

Originally Posted by jcmo

OK, that's good insight, I appreciate your input. That leads me to a couple more questions to help me quantify what we're talking about here a bit better. Is this "Power" as expressed in watts? Torque?

Watts, not torque.

One way to measure the power is simply by how much of the battery you use up, that is, by measuring power consumption.

If you have two different motors, each running at full power for 2 minutes starting with a fresh battery, you can compare the battery recharge times after those 2 minutes. The longer the battery takes to recharge (at a constant rate), the more powerful the motor, and this is a nice, simple relationship. If the battery takes twice as long to recharge, it was running a motor that was twice as powerful. (And that doubly powerful motor gives you, very approximately, one and a half times as much lift.)

This also means that to get that extra 50% of lift you have cut your flight time about in half (if you fly the heli at full power and don't upgrade the battery).

[jcmo]

Good stuff, JMHoffman, thanks again for the input. The Scorpion was waiting for me on my desk when I arrived today. Now I wonder how much difference in performance a person will see in one motor and another based on ESC alone.

SHYguy, I recall reading you are using a 40a esc, right? Did you set the timing, etc, according to Scorpion's website? I thought I noticed some things there that looked out-of-place compared with the settings for the stock motor or Wicked that I have seen discussed in threads here. I don't intend to insult you, LOL, in fact I firmly believe you know what you're doing better than I do - this is my first time customizing a "big" heli like this. I wonder though, if the YEP 45 would push any differently than a 40a, assuming that both are adequate to drive the motor. Would the "extra" 5A of current capacity give any more oomph, or does the 40A already give enough power above what the motor needs that the difference is negated?

To softly pull this back on topic - perhaps if the 45A works better than a 40A, the extra weight is worth carrying. I don't know, but I'm excited about seeing the Scorpion in action.

[SHYguy]

I use the stock 25A ESC now, due to low v servos I use.

Will use the light weight YEP30 with gov. Plus CC BEC.

45A is overkill and just dead weight, those are for 450 size helis. Will not give any added HS here

[Nelsonisms]

To put it another way. Don't think of the amp rating of the ESC as a difference in power being "pushed" to the motor. Think of it more as the throughput capacity of the ESC. The motor will draw however many amps (current) it needs depending on the load placed on it for a given voltage (potential) and before it would internally fail from overcurrent. If that amp draw exceeds the rated capacity of the ESC then it will likely overheat it. So the higher rating of the ESC is simply to allow breathing room above the maximum possible current the motor will attempt to draw. But having an ESC that is rated far above the maximum amps that a motor can draw does not provide more "power" it's just added weight. So the best power to weight ratio is achieved by using an ESC that is rated just slightly above that maximum amp draw of the motor with a given load.

That's why I really love my Castle ESCs because you can easily review the min/max/avg amp draw in the logs.

I forget exactly what my 300X is drawing right now, but suffice it to say it's well under the 50A rating of the Ice Lite 50. So it is definitely overkill as far as capacity but I don't think it's much heavier than the stock ESC, if any (never weighed them).

[jcmo]

I had a sneaking feeling in the back of my mind that the difference between 40 and 45 amps would only show itself if the motor were on the border of being starved for power at 40A. I understand now, putting a 45A ESC on a motor that will only draw 25 is needless.

SHY, with the stock ESC on there, I realize that you do not have the programming options offered on many ESC's. I wonder if part of the reason for the Scorpion's performance lacking zip on the E-Flite ESC has anything to do with the timing settings of the motor. I know the pole count is the same, but I think some of the other critical details differ a little bit. My memory for such things hasn't developed fully yet, so here's the stuff from Scorpion

HKII-2213-14 Specifications

Stator Diameter	22.0 mm (0.87 in)
Stator Thickness	13.0 mm (0.51 in)
No. of Stator Arms	9
Magnet Poles	6
Motor Wind	14 Turn Delta
Motor Wire	11-Strand 0.21mm
Motor Kv	3585 RPM / Volt
No-Load Current (Io)	1.74 Amps @ 10 volts
Motor Resistance (Rm)	0.038 Ohms
Max Continuous Current	32 Amps
Max Continuous Power	330 Watts
Weight	54 Grams (1.90oz)
Outside Diameter	27.9 mm (1.098 in)
Shaft Diameter	3.17 mm (0.125 in)
Body Length	30.3 mm (1.193 in)
Overall Shaft Length	50.7 mm (1.996 in)
Max Lipo Cell	3s
Motor Timing	5deg
Drive Frequency	8kHz

Timing and Drive Frequency are what I'm focused on. I think I've seen different settings recommended for the Wicked and Parkfly motors. Anyone recall what I'm talking about?

EDIT: WOW... I'm a doorknob. I'm regurgitating information from a conversation that went on between you guys and DCH some time ago. I was wrong, the timing and frequency are the same. At least I remembered reading about it before so I am learning a lot from you guys Please forgive my questions where they cover ground you've discussed before - I'm usually better about using the search function and completely reading threads before asking