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Old Oct 19, 2012, 10:20 PM
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[QUOTE=bobly;23049205]As kv is supposedly rpm in relationship to volts, apparently something is wrong with e-flight's calculations or static tests don't tell much. With same battery and prop the 2300 in the beast seems to be easily producing more rpm per volt than the 2500 at least in static conditions. It's a shame we don't have telemetry to let us see what they do in the air. You don't have any smaller prop to simulate at least a partial unloaded situation do you. Way back when I fooled with speedboats, we had test props to run in test tank that simulated what could be expected from standard props in real life. No way to tune an outboard motor in test tank with standard prop, they just can't turn the rpm's and motor is badly overloaded when stationary in the water.

Just happened to think, 2500 kv motor at 7 volts should be turning 17,500 and 2300 should be turning 16,100 at a minimum unless overpropped.[/QUOTE

These numbers clearly reveal a mismatch between observed results and calculated results ,,IMHO. :-),,,,, but your mileage my vary. ;-)
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Old Oct 19, 2012, 10:21 PM
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Joel my thirteen minute flight was mixed between slow circuits, takeoffs, landings, and all out try to rip the wings off, I was suprised at my time to as my timer is set for 5 min and I was having so much fun I landed and seen I went 8min 35 past the 5min lmao, 282 mah back in pack on a low amp balance charge setting, and yes I know about the gyro gain occilation, if a slight bit of up is applied it dosent do it, only if I put it in a slight dive with neutral controls... I dont think the oversized horn hole is helping, and have not crashed or had any prop strikes...yet...lol
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Old Oct 19, 2012, 10:24 PM
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Joel my thirteen minute flight was mixed between slow circuits, takeoffs, landings, and all out try to rip the wings off, I was suprised at my time to as my timer is set for 5 min and I was having so much fun I landed and seen I went 8min 35 past the 5min lmao, 282 mah back in pack on a low amp balance charge setting, and yes I know about the gyro gain occilation, if a slight bit of up is applied it dosent do it, only if I put it in a slight dive with neutral controls... I dont think the oversized horn hole is helping, and have not crashed or had any prop strikes...yet...lol
Whoa!!! SCAREY
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Old Oct 19, 2012, 10:27 PM
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My 2500kv on this sbach performs awsome, I agree that only accurate test would be in the air when they unload, I also thought the 2500 sucked but im having great reasults from this one.
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Old Oct 19, 2012, 10:27 PM
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Don't like the dolphin tail wiggle thing!!!!! :-)
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Old Oct 19, 2012, 10:29 PM
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Originally Posted by Planecraazy View Post
My 2500kv on this sbach performs awsome, I agree that only accurate test would be in the air when they unload, I also thought the 2500 sucked but im having great reasults from this one.
Very weird on this one that seemingly same motor having different results!!!
Bringing me back to my motor timing issue I brought up a few posts back,,, just a theory
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Old Oct 19, 2012, 10:30 PM
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So what's the consensus here on best overall battery for this bird???
I just recently ordered 5 - 260 mah 35c nanos for her,,, will these work good???
They'll work much better than any of the Eflite packs and the other cheap packs.

The TP 325 65c Babbelbatts are clearly the best overall performers. They definitely have the best vertical performance, and they're faster than all but the Hyp 500 35c. The Hyp 500 is fine for sport & endurance flying, and for flying in the wind, but it's too heavy for good aerobatic performance. From my testing of the new Hyp 500 35c pack, I can tell that the Hyp 400 35c will most likely provide the best overall performance of the current factory-made 'UMX' packs. The Hyp 240 or the Nano 260 would be better for 3D, due to their lower weights.

Check my battery comparison videos & static RPM results.

A big benefit of going with the Hyp packs is that they usually last for at least 200-300 cycles before they start to fade away - even when charged at 5c all the time. At $10 USD, & a rated cycle-life of 300+, the factory Hyp 240 is a real bargain. At $12 USD, the new Hyp 400 35c is a steal! TP claims 600 cycles with their G6 packs, and the 65c versions are designed for a whopping 12c charge! Unfortunately, TP doesn't make a 'UMX' version of the 325 65c pack, so you'd have to either change connectors on the plane or pack, or get UMX versions from RCBabbel.

Joel
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Old Oct 19, 2012, 10:31 PM
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Didn't get the video finished tonight, Tomorrow for sure. Did get a short video of my B3D doing a KE spin and a Lomcevak though. Its over on the Beast thread.

-Brian
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Old Oct 19, 2012, 10:38 PM
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Originally Posted by Planecraazy View Post
My 2500kv on this sbach performs awsome, I agree that only accurate test would be in the air when they unload, I also thought the 2500 sucked but im having great reasults from this one.
They certainly have to be performing well when flying and unloaded. Any electric motor loaded so heavily to make it be that far under rated kv could not last long at all. Any electric motor has a rated rpm at a specific voltage and that is where they must operate if they are going to last at all. I feel pretty comfortable that if you could check rpm unloaded in the air you would find numbers that match the math as long as it was propped right.
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Old Oct 19, 2012, 10:39 PM
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Originally Posted by turboparker View Post
They'll work much better than any of the Eflite packs and the other cheap packs.

The TP 325 65c Babbelbatts are clearly the best overall performers. They definitely have the best vertical performance, and they're faster than all but the Hyp 500 35c. The Hyp 500 is fine for sport & endurance flying, and for flying in the wind, but it's too heavy for good aerobatic performance. From my testing of the new Hyp 500 35c pack, I can tell that the Hyp 400 35c will most likely provide the best overall performance of the current factory-made 'UMX' packs. The Hyp 240 or the Nano 260 would be better for 3D, due to their lower weights.

Check my battery comparison videos & static RPM results.

A big benefit of going with the Hyp packs is that they usually last for at least 200-300 cycles before they start to fade away - even when charged at 5c all the time. At $10 USD, & a rated cycle-life of 300+, the factory Hyp 240 is a real bargain. At $12 USD, the new Hyp 400 35c is a steal! TP claims 600 cycles with their G6 packs, and the 65c versions are designed for a whopping 12c charge! Unfortunately, TP doesn't make a 'UMX' version of the 325 65c pack, so you'd have to either change connectors on the plane or pack, or get UMX versions from RCBabbel.

Joel
THANK YOU!!! Very good Info!!!!!
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Old Oct 19, 2012, 10:47 PM
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Joel, do u feel this new sbach does have more power in flight, I havnt been flying as regularly as I used to, dont know if my mind is playin tricks lol, anyone else feel it has more power?
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Old Oct 19, 2012, 11:57 PM
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Originally Posted by bobly View Post
They certainly have to be performing well when flying and unloaded. Any electric motor loaded so heavily to make it be that far under rated kv could not last long at all. Any electric motor has a rated rpm at a specific voltage and that is where they must operate if they are going to last at all. I feel pretty comfortable that if you could check rpm unloaded in the air you would find numbers that match the math as long as it was propped right.
Nevertheless, the 2300Kv motor very obviously outperforms the 2500 in every test-report and video, and flight-times are also far better - and this is true with any of the commonly-available UMX-sized props. This has been proven many times over by a number of people. Therefore, the 2300 is more efficient than the 2500 in any of these UMX airframes.

Joel
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Last edited by turboparker; Oct 20, 2012 at 12:41 AM.
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Old Oct 20, 2012, 12:30 AM
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Originally Posted by bobly View Post
....
Any electric motor loaded so heavily to make it be that far under rated kv could not last long at all. Any electric motor has a rated rpm at a specific voltage and that is where they must operate if they are going to last at all.
...
Back in the day when motors had brushes this was correct. These days motors are a lot more tolerant of being loaded down. If you don't melt the insulation (pretty hard to do) the motor will be OK.
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Old Oct 20, 2012, 12:40 AM
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Originally Posted by kalmon View Post
I've highlighted the gold standard Hyp240 in the most common setups for easy comparison.
Code:
3000kv + GWS 5030			
Battery	RPM	Thrust 	Speed
hyp240	12240	142	34.8
hyp300	12600	151	35.8
tp325	12800	156	36.36
			
2300kv + 5043			
Battery	RPM	Thrust 	Speed
Hyp240	9700	129	39.5
Hyp180	9600	127	39
			
2300kv + GWS 5030			
Battery	RPM	Thrust 	Speed
Hyp240	11300	124	32.1
Hyp180	11300	124	32.1
			
2300kv + Stock			
Battery	RPM	Thrust 	Speed
Hyp240	11150	111	29
Hyp180	11150	111	29
			
2500kv + Stock 5"x2.75" V4			
Battery	RPM	Thrust 	Speed
Hyp240	10530	98	27.4
Hyp180	10380	95	26.8
			
2500kv + GWS 5030			
Battery	RPM	Thrust 	Speed
Hyp240	11000	118	31.3
Hyp180	10860	115	30.8
Joel have you ever tached any of the motors on 3S. For grins it'd be funny to compare them.

-Brian

Brian,

I can get you some 3S #s on Monday.
B3D & V1Sbach.
Stock 2500Kv motors.

For now, my old 3SB3D post in Jan...
http://www.rcgroups.com/forums/showp...ostcount=13712


rc
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Old Oct 20, 2012, 12:45 AM
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Just 'cuz I hope to get answers, the last paragraph has a question!

I flew my Sbach with a GensAce 450mAh battery at WOT for 6 minutes. The batt still showed 3.8v! Be interesting to see what the charger puts back, but it didn't get into the danger zone. That's a different kind of flying for me. I actually enjoyed just ripping around. Fun! Now I'm glad I did a little foam carving to fit that batt.

But that same flying session I had the rudder stick. Dang it, I finally got bit by these rotten servos. So I KE'd it in but couldn't figure out how to get it slowed down because the rudder wasn't stuck far enough. So I got a little damage.

So... I hope you're still with me on this post because I have a question: I want to use FoamTac for the repair for my first time. But the damage is just cracks and you have to pull the pieces apart to get any gap visible. So how do I apply FoamTac and let it air dry for 20 minutes before pressing the parts together? Do you wedge it apart with a little something?
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