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HomeAircraftHelicopterGasser Model RC HelicoptersOther › Predator Carbon SE gear Ratio
10-14-2005 09:37 PM  12 years agoPost 1
FAA

rrApprentice

MIlford CT

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Doesn't the SE version come with the speed up gears ?

I had a 14T and a 13T helical gears set for the gearbox in my kit.

Is that different from the Standard version of the Kit ?

Everything else was stock (whatever comes with the Carbon SE kit). What would my gear ratio be ?

I will need this for my govenor setup.

Thanks

Nick

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10-14-2005 09:52 PM  12 years agoPost 2
JKos

rrProfessor

Redondo Beach, CA

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> I had a 14T and a 13T helical gears set for the gearbox in my kit.

Yes, that is the speedup gear set. I believe the speedup gears are now standard for all the kits.

> What would my gear ratio be ?

Should be 6.28.

- John

RR rules!

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10-14-2005 10:16 PM  12 years agoPost 3
FAA

rrApprentice

MIlford CT

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This is where I am confused.

The main is 88T.

The Original kit had 14T to 14T ?? so the original gear ratio was 6.28

The Speed up kit has 14T to 13T ?? so the new gear ratio is 6.77

Is all this correct ?

Nick

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10-14-2005 11:19 PM  12 years agoPost 4
Billme

rrElite Veteran

MS

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The speed up gears are standard now...If you are talking about pinions, and have the 13 tooth pinion, and 88 main, you have the 6.7 ratio, hense you need the speed up gears running the 110 or 115mm tail blades...Runnng the speed up gears with the standard 6.28, you need to run the smaller tail blades105's and 110s
Bill

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10-14-2005 11:20 PM  12 years agoPost 5
UpstateRotor

rrApprentice

Upstate NY

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I believe you are getting 2 issues confused. The "speed up" gears are for the tail rotor. The ratio for the governor is the number of teeth on the OUTSIDE of the main gear divided by the number of teeth on the pinion...the gear on top of the clutch bell.

Additionally, some of the "stock" kits that are out there have been modified. One example is the gearing. The "Agrav8" version of the predator that is available through Ron Lund's team is a perfect example. The gearing in that kit is 6.77 (88/13), while the "original" kit was 6.28 (88/14).

Shawn

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10-15-2005 03:51 AM  12 years agoPost 6
FAA

rrApprentice

MIlford CT

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Ok. I got the part of the tail gears. Still confused with the gear ratio for the governor.

According to "UpstateRotor":

"The ratio for the governor is the number of teeth on the OUTSIDE of the main gear divided by the number of teeth on the pinion...the gear on top of the clutch bell."

And I agree with that.

However ...

Step 29 in the manual identifies the clutch bell assembly with the pinion as a 15T.

The main gear is a 88T. Again this is the Carbon SE kit.

The gear ratio comes out to be : 88/15 = 5.86

What am I missing here ?

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10-15-2005 03:57 AM  12 years agoPost 7
FAA

rrApprentice

MIlford CT

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OK.

Now I am royally confused.

Just counted the pinion. Its 14 teeth. Why does the manual in step 29 identify it as 15T ?

88/14 = 6.28

So if I wanted to "upgrade" this puppy I would have to get a 13T pinion

Is this the correct century p/n HW6018C for the 13T ?

Thanks to all that have posted their help.

Nick

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10-15-2005 04:14 AM  12 years agoPost 8
rbort

rrProfessor

Franklin, MA - USA

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Gear ratio
Nick:

You count the outside teeth of the main gear to the teeth on the clutch bell. Stock is 14 / 88, upgrade is 13 / 88. Go with the 13, the engine turns a little faster and you get into the power band better. I've been using 13 teeth on my 1005 gasser for quite some time (7 years or so) and it runs awesome with the Hanson engine.

On the contrary, do not upgrade the tail rotor to the high speed gears (in the tail box). It will make your tail alot more sensitive and for the average joe the feel of the tail is alot more twitchy and not solid. Only people who like that are people who fly jerky, or do heavy 3d in my opinion.

-=>Raja.

MA 1005 Hanson 280, 4220 flts
Spectra 27 3DMax, 3310 flts
Whiplash V1-2 Hanson 300, 1618 flts
Whiplash V2 Hanson 300, 473 flts

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10-15-2005 04:18 AM  12 years agoPost 9
AGRAV8

rrProfessor

Mosquito Coast......Houston Texas

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depends......
the manual was originally written when they were using 5.8 (15/88) ratio. We discovered that Zenoah had not stated the rpm range for the 231 very well, and went to the 14/88 as standard. This ratio is still the recommended ratio for a modified G-26 engine. Some kits are configured for the 231 (on request from Ron Lund specifically) and have the 13 tooth pinion with the 88 tooth main (6.76).

Personally, I use a lower ratio than that on my 3D gasser....13/92 (7.07)

I would suggest the 14/88 for the general sport flier....with either engine. For the ones that really press it hard, the 13 tooth would be a suggestion.

FWIW, I have 1800, 1900, 2,000 for GV-1 settings. At 2,000 headspeed, the engine is turning 14,140 RPM ! MUCH higher than the 10,500 range stated by Zenoah. I use the torpedo muffler as well.

If you use the 14/88, you should have 1800 as your normal headspeed. It just seems to be happier there VS a lower speed. Either engine.

I like and suggest the 14/13 tail speedup gears. It is not too sensitive IMHO.....and it is only a 7% increase. I have Rotortech 115's on mine with them at the above headspeeds. No issues.

"Is this the correct century p/n HW6018C for the 13T ?"

Yes.

Hope this helps clarify your questions.

James

GOOD guy list-39, BAD guy list-0

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