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Other › RPM.....HELP!
02-09-2006 05:16 PM  12 years agoPost 1
e-jag

rrNovice

Sioux City, Ia.

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Hi Guys,
I hope someone can help me out?! I have a T-Rex HDE
and with the following set-up I can only achieve main rotor
rpm of about 2100.The controls seem somewhat sluggish, and
the motor does not appear to be working at peak efficiency!!
Mega 16/15/3 with 9 tooth gear
C.C.45 controller with the following settings:
cut off voltage@ 7.2
current limit option 3- Standard setting
brake off
Throttle type- option 4 (Governor Mode high rpm range)
Electronic timing advance- High Advance 12-35 degrees
Soft start and cutoff
PWM Switch Rate- option 1 (11 KHz)
I use a JR 8103. in the ST-1 Mode
Throttle Curve- All points set to 100%
Pitch Curve- 0, 10.5, 32.5, 55, 81%
The main rotor pitch is approx -9 to 9 from
Zero to full throttle on the radio
I would like to be able to achieve a Main Rotor RPM of about 2400!?
Using the above and a 401 Gyro with a HS 50 Servo I continue to
have a fine side to side tail wag despite trying to adjust the Gain
Sorry for the Looooong post, but I'm on my own as I am the only
Heli Pilot in our club. Thanks in advance for any help B.P

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02-09-2006 05:44 PM  12 years agoPost 2
lbowen

rrApprentice

York S. Carolina-USA

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I would suggest you go to Trextuning.com to read set up info for pit/pwr curves and ESC - most suggest not having current limiting and other setting you have - the site I referenced has a lot of info and the reasons. You can use settings to get all the power your battery and ESC can supply for your motor - IMO you do not have those settings now.

lbowen

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02-09-2006 05:54 PM  12 years agoPost 3
smoothound

rrVeteran

Lancing, West Sussex, UK.

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Off the top of my head I'd say you need a bigger pinion. You don't say what cells you are using but I'm guessing 3s if so you need at least a 12T if not 13T to get good headspeed

Phil

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02-09-2006 06:37 PM  12 years agoPost 4
e-jag

rrNovice

Sioux City, Ia.

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Thank-You Very Much for your replies!!!

I had forgotten all about the t-rex tuning site:
I'll be checking there first!!
I'm NEW to this electric heli business. I'm just
not sure which factors to adjust and how.... Throttle
and Pitch Curves,Gearing, ESC,Gyro, or some combination
and change in all of them!!! I'm using a 2100 3-cell Lipo.
I'm sure I'll get right eventually B.P.

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02-09-2006 06:48 PM  12 years agoPost 5
Ozydego

rrKey Veteran

Westerville, Ohio

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what is the KV rating of the Mega?? I would say definitely go with a higher pinion.. use the Headspeed calculation for different pinion sizes with your setup to get the rough headspeed you want:

(Kv * voltage) * efficency rating * (pin / main) = headspeed

If you can't find the efficiency rating of your motor, use 85%, (.85), the main gear is 150 teeth and your voltage is 11.1, so get that Kv number and start plugging away:

(Kv * 11.1) * .85 * (pinion / 150) = your headspeed

But Honey, I can't live with just stock.....

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02-09-2006 07:05 PM  12 years agoPost 6
exeter_acres

rrApprentice

Johns Creek, GA

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mega 1615/3 is a kv of 3000 with an eff of 87%

I'm old, bitter, and don't like people.... get over it

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02-09-2006 07:15 PM  12 years agoPost 7
BrainDrain_dx

rrKey Veteran

Wichita KS

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pinion calc

KDS Agile 7.2/5.5 Chase 360 - SkyHero Spyder/Spy/Little Spyder
Sponsored by my Visa

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02-09-2006 07:16 PM  12 years agoPost 8
Ozydego

rrKey Veteran

Westerville, Ohio

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Well, then the pinion you are using now "should" yield a HS of 1740, or, way low. Here are the pinions and their HS:

11 tooth: 2110
13 tooth: 2520 ***
14 tooth: 2700
15 tooth: 2900

I would go with the 13 tooth pinion, to avoid excessive heat, if you want to push it, you could use a 14 tooth pinion, but I would stick with the 13, a definite increase over the 9 tooth.

But Honey, I can't live with just stock.....

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02-09-2006 07:56 PM  12 years agoPost 9
e-jag

rrNovice

Sioux City, Ia.

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Again, Thank-You very much!!
As always, your advice is Right On!!
I changed the pinion, went to the T-Rex
Tuning web site and adjusted the Throttle
and Pitch Curves as mine were "Less than
Optimal" to say the least!!!
Problems solved!!..... it flies like a
different heli! It Always helps to have
it set up Properely!!
Another satisfied customer, thanks
to the members at RR!!! B.P.

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