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Old Nov 08, 2011, 03:47 PM
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Look here. The 4025 is the best prop for the AP03 7000kv.

http://home.comcast.net/~gordon-johnson/lcd-apo3.htm
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Old Nov 08, 2011, 04:34 PM
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It's certainly the best prop for it out of the three in that table. For a park flyer sized plane, I'd want much better efficiency than that (smaller prop) - e.g. comparing the 4000Kv and 7500Kv with the same 4025 prop, the 7500Kv is drawing twice the current to produce less than 50% more thrust and about 20% more speed.

Even so, neither motor gets used near their efficiency points so I guess it's a case of getting as much thrust as you can without burning it out. I'm surprised the 4000Kv can only produce 33g of thrust (with a 5x3) but that does bear out what modfly and others were saying about 1s brushless setups. Does anyone know the thrust of the stock 4-site motor with a suitable prop?

I guess the easiest thing for Nooflyer to try at the moment would be the 7500Kv AP03 with the 4025, but a bigger capacity (heavier) cell to handle the higher current. It will just mean shorter flight times. The 4-site setup would be lighter and would be able to fly slower, but may not give enough thrust for 3D.
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Old Nov 08, 2011, 05:05 PM
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The 4-Site motor weighs about 7.5g, and makes ~40g of thrust. The AP03 is pretty similar, but weighs about 4g with appropriate ESC.

It should be noted that that a nearly identical motor wound to ~15,000kV and geared 6:1 will produce almost twice the thrust on the same propeller with slightly reduced current. Also, the Hobbyking 1s ESCs all have poor efficiency due to high internal impedance - a YGE-4L or similar can give up to 20% more thrust.

(If anyone can find me a 14,000+ kV 3g motor under $30, I'll try and Shapeways a gearbox.)

Most folks just go with an AP05. It turns out that if you strip down a cheap XP-7A ESC and pull the redundant battery leads on the Parkzone brick, the total weight is only about 7.5 grams. Of course, you need a second battery, but 110g of thrust makes this somewhat moot.

Alternately, does anyone know if a large, low-pitch propeller would allow the AP03 to perform better? Perhaps a 5x2? I think such things have been used on 40,000RPM pylon racer engines.
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Old Nov 08, 2011, 05:11 PM
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This is true and Ive done it; plush 6 works as well stripped down BUT I have never had it produce more than 100 grams of thrust; more like 97-99 with 5030 prop.




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Originally Posted by Cheesehead View Post
The 4-Site motor weighs about 7.5g, and
makes ~40g of thrust. The AP03 is pretty similar, but weighs about 4g with appropriate ESC.

It should be noted that that a nearly identical motor wound to ~15,000kV and geared 6:1 will produce about 50% more thrust on the same propeller with slightly reduced current. Also, the Hobbyking 1s ESCs all have poor efficiency due to high internal impedance - a YGE-4L or similar can give up to 20% more thrust.

Most folks just go with an AP05. It turns out that if you strip down a cheap XP-7A ESC and pull the redundant battery leads on the Parkzone brick, the total weight is only about 7.5 grams. Of course, you need a second battery, but 110g of thrust makes this somewhat moot.
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Old Nov 08, 2011, 05:19 PM
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The Miniaviation 190mAh cells are only about 1.2g heavier than the standard 130, and are reputedly worlds better than the standard Parkzone products. They're a little spendy, but 2.8A shouldn't be an issue.

Quote:
Originally Posted by Razors edge 29 View Post
This is true and Ive done it; plush 6 works as well stripped down BUT I have never had it produce more than 100 grams of thrust; more like 97-99 with 5030 prop.
That's interesting. The quoted figure might be on a fresh 8.4v battery and/or a better ESC.
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Old Nov 08, 2011, 05:24 PM
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Quote:
Originally Posted by Cheesehead View Post
The 4-Site motor weighs about 7.5g, and makes ~40g of thrust. The AP03 is pretty similar, but weighs about 4g with appropriate ESC.
Cool. I was thinking the 4-site motor was lighter. So that allows for 3.5g more battery to get to the same weight, which should do nicely for getting more power out of the AP03 7500Kv.

I think the 4-site setup would probably be more efficient, giving longer flight times (I get a good 7-8 mins with the SU-26 I made into a biplane on a 5x3 and a 138mAh lipo) but just using the existing setup with a bigger cell is the easiest thing to try at the moment.

A more efficient ESC would be good, yes.
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Old Nov 08, 2011, 05:27 PM
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Love the info.
Thanks, maybe i should get ahold of some 5x3 and more 4x2.5 props. I do have 6 HK single cell 240mah lipos laying around. Just need to buy jst xh connectors.
But these batteries are only 20c rating, i also here they don't live up to 20c in discharge.
maybe 14c tops?

Another question if this will make a difference. I have my esc connected directly to the Ar6400 brick, and am using the battery plug from the brick. Does it make a difference in power to the motor if i have the battery coming for the esc instead of the brick?
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Old Nov 08, 2011, 05:30 PM
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Does it make a difference in power to the motor if i have the battery coming for the esc instead of the brick?
It could do, yes. The extra resistance from running the power through the tracks on the brick could make a difference, especially at nearly 2.5A.
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Old Nov 08, 2011, 05:41 PM
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Quote:
Originally Posted by Nooflyer View Post
I do have 6 HK single cell 240mah lipos laying around. Just need to buy jst xh connectors.
But these batteries are only 20c rating, i also here they don't live up to 20c in discharge.
maybe 14c tops?
240mAh cells sound about right, and only need to be capable of 10c with the 4025, which is about what I'd normally aim for. If you're having to buy connectors, I'd consider the polarised pin and socket type micro connectors instead of the Spektrum/Parkzone type. They should be a bit lower resistance.

The current figures for the 5x3 in that table boredom.is.me linked to look a bit low, considering the current with the 4025. Bear in mind that the real rating of your 3.5A ESC is 3A continuous, according to the manual, and the table predicts 3A max for the motor. It's probably not worth pushing it for an extra 3g of thrust.

If you can find a bigger diameter but low pitched prop, like Cheeshead suggested, that would be a safer bet than the 5x3. The motor would run more easily - it's clearly being bogged down with the 5x3 - so it would be more efficient and use less current than the 5x3, and you'd still get more thrust than with the 4025.
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Old Nov 08, 2011, 05:42 PM
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Thanks i'll try and rewire the battery plug to esc and test it.

Anyhow i finally managed to swap in the brushed motor.
All tested and went well. It definately pulls with the new 150mah 25c battery.
Now just waiting for the perfect day.!
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Old Nov 08, 2011, 05:55 PM
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That was quick. I was thinking it would be a lot of trouble to change the motor and remove the ESC. I'll be interested to hear how it goes.

If it performs as it should, I'd probably keep it like that til the motor wears out. Those geared coreless motors are pretty good while they last. You won't get a lot more power without going to a 2s setup.
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Old Nov 08, 2011, 07:44 PM
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Quote:
Originally Posted by Andy2No View Post
You won't get a lot more power without going to a 2s setup.
I think the max from a geared ~3g brushless motor was about 70g.
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Old Nov 08, 2011, 09:21 PM
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Ok,
I've been browsing the internet for the last couple hours since finishing the extra!
As something is telling me that i should make a micro GeeBee Racer since i can't use my Ap03 7500 kv motor for 3D. I have plenty spare parts laying around to suffice another micro for the more windy days in the plains (kansas).

I know E-Flite is coming out with one but i'm not wanting to dish out $170 when i can build one with the supplies i already have. Plus, i want to stay with 1cell lipos for affordable reasons.

Just in the building mood because i only have one working plane to fly. And i can't fly right now because the weather just won't permit.

Anyhow, this will be my first pylon racer type plane and i want to explore outside of 3d for a more relaxing but adrenaline bound flying.
Now come on guys and keep posting your micros!
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Old Nov 09, 2011, 05:40 AM
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looks awesome Nooflyer! AUW with and without batt?

SS
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Old Nov 09, 2011, 08:14 AM
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Quote:
Originally Posted by Cheesehead View Post
I think the max from a geared ~3g brushless motor was about 70g.
Was that one one cell? If so, that's impressive.
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