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Old Jan 11, 2005, 03:46 PM
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Chester, UK
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ECO 8 stock motor beats Mega 22203H hands down???

Surely not! My ECO flies happly round with the original sport motor on 8 cells/11T, but with a Mega 22203H (8 cells/22T) it just about hovers at 4ft. Too much throttle and it gives up. What am I doing wrong!

Set up - Mega 22203H (with Lego fan!), Phoenix 45, Sanyo CP2400SCR, 2 mins into test run ESC fed 8.55v, 21.7A, head speed 1291rpm, batteries provide 1859mAh during test with 357mAh remaining. I have struggled before with this set up when new motor seemed 'tight' and wouldn't start but has now eased. (full run data available to anyone who's curious)
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Old Jan 11, 2005, 05:08 PM
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Too many teeth on the pinion, try 16.
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Old Jan 11, 2005, 05:16 PM
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Chester, UK
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ashdec87

Have tried 20T with similar results, am awaiting delivery of 15T but I thought that was best for 10 cells having checked KC's excellent spreadsheet in another thread (and others pinion calculators). I am still intending to change from tamiya connectors in case they are at fault but they are common to both set ups.

Tony
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Old Jan 11, 2005, 05:30 PM
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Oh good grief.

The recommended pinions on 10 cells are 13-15T. For 8 cells you multiply by 10/8 so it's 16-18T.

20T is way too many, and it won't fly on 15T.

Helicopters aren't planes; you can't randomly choose pinions and hope it will work.

And the Tamiya connectors are only good to about 8 amps max, and you're running them at 20 amps...

Plus you may have already damaged your battery packs by overloading them on a 20T pinion.

Toshi
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Old Jan 11, 2005, 05:44 PM
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Chester, UK
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Toshi

I fear you are right and I may have damaged the battery packs. But the motor Kv gives:- 1850 x 9.6 x 0.85 * 20 / 180 = 1677 rpm (ehbg14), hence my original choice of 20T not the 22T recommended by ElectricRotors in the UK. Indeed the FXA calculator checks 20T at 1644rpm max to 1390rpm heavy load. What am I missing in my calculation? - and yes you've gessed it I've only been flying for 3 months.

Tony
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Old Jan 11, 2005, 05:56 PM
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Those calcs dont take into account loads and such..

It's proven that on 8 cells, a 16 T pinion works best. I used to run that exact set up and it had great power..

I now use 10 cells on 14 T, but i'm gonna change that sometime..

ash
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Old Jan 11, 2005, 05:58 PM
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St. Mary, Maryland, United States
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Do you have a heli radio? You need the throttle to get up to about 80-85% by the time hover pitch is reached. You've most likely got a serious mismatch between the throttle curve and the pitch curve. Trying to pull 6 degrees of pitch at 40% throttle will not work.

Disconnect all three motor wires then connect your ESC. Observe the LED and smoothly move to full throttle. The LED should light solid just as you reach full stick. If it is still blinking increase your high throttle ATV until it is fully lit. If it comes on solid very early then reduce the top end ATV. Now go to the throttle curve and make it 0-85-100 and see how it works.
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Old Jan 11, 2005, 06:18 PM
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Chester, UK
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Ash - thanks I'll take the recommendation although I would still like to know how to modify the calculation, is there a 75% efficiency figure in there or something? I think Toshi has a point with the connectors (I thought rated 25A), but they may be causing excessive voltage drop.

Chris - I have an Futaba FF6 which is not a specialist heli radio and hence only allows a three point curve. I have set hover throttle (HV-T) to +50% which I think gives me 0-75-100, pitch is linear. My tests were done at 65% stick position which is 5.5-6.0 degrees pitch and about 80-85% throttle (if I have understood the 'HV-T' setting correctly?). I shall carry out the ESC check tomorrow.

Thanks
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Old Jan 11, 2005, 06:53 PM
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There's no real way to perfectly reproduce the real world, even motocalc isnt accurate. They all only take number and plug them together. The best tool is rcgroups..there tons of people who have tried every combo out there..

I hate to say, but that radio wont take you very far, especially with the eco 8..i really suggest getting a heli radio ( i was an eclipse 7) It'll make life SO much easier for you..

I dont think a 0-75-100 will give you a linear curve, 0-50-100 will.. throttle should be around 90% 80-85 might be a bit too slow..or that's what i found..

And get deans connectors..they are SO much better, quite a power increase. And i've had the tamyia cut out on my once..very scary to jsut see the heli drop..

ash
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Old Jan 11, 2005, 06:53 PM
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San Carlos, California, United States
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1291 rpm on 20T/8 cells is really weird too..

That could be the Tamiya connnectors, though. They are just utterly garbage in my opinion. I use Astroflight Zero-loss connectors on my helis.

Toshi
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Old Jan 12, 2005, 07:49 AM
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Tony,

Best advice would be to keep the FF6 for use with planes and invest in a decent heli radio that has 5 point pitch and throttle curves. JR offer two or three TX's that can be had for between 90 and 250, there is also the new FF7 from Futaba. Best place IMO is Inwood Models in the UK.

As for connectors, I use "dean" type connectors from Hillcott Electronics http://www.hillcott.plus.com/ These are rated at 50 amp so you should be fine for use with the Eco 8 - He is in the process of updating his site, but will take orders via the phone.
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Old Jan 12, 2005, 10:55 AM
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Chester, UK
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Tamiya connectors are history! Go for gold!

1291 rpm on 20T/8 is indeed weird. Tachometers can read harmonics, but this would translate to 2582rpm (at x2) which is equally too high and does not conform to the Kv for the motor under the test conditions.

I have heard from several people that I should go for a JR TX and am seeking model opinions, but for the time being the HV-T settings are from Dream Models until budget (and wife) allows...
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Old Jan 12, 2005, 12:30 PM
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Chester, UK
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Chris - At full travel, with full high throttle ATV (120%), the LED does blink-blink-pause. If I increase STRIM also (sub-trim was at 0%) to maximum the LED stops the double blink and blinks once then pause. I cannot get the LED to stay on at all!
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Old Jan 12, 2005, 01:49 PM
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Roswell, GA
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Why don't you just use governor mode with your P-45? Works great on mine, also using the 22/20/3H (14 tooth pinion on 10 cells). If you don't have the latest firmware you'll want to get it - easy to tell, if you're getting a nice smooth slow startup you've got it. Older versions were pretty harsh...

For the money a Futaba 7CH transmitter is a good deal, I love mine
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Old Jan 12, 2005, 05:17 PM
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St. Mary, Maryland, United States
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Quote:
Originally Posted by tonywarr
Chris - At full travel, with full high throttle ATV (120%), the LED does blink-blink-pause. If I increase STRIM also (sub-trim was at 0%) to maximum the LED stops the double blink and blinks once then pause. I cannot get the LED to stay on at all!
OK, you learn something everyday! The ESC needs the motor connected to give the proper blinks as described so hook the motor up again BUT REMOVE THE PINION GEAR. Once the ESC sees the motor as a load the led will first light very dimly as the motor begins to turn then get brighter until it clicks to full brighness at 100% throttle.
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