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HomeAircraftHelicopterThunder TigerOther › R60/90 and OS70SZ gearing
02-12-2006 09:05 PM  12 years agoPost 1
jsenicka

rrProfessor

Eagle River, WI

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Howdy.
I have a near new OS70 and a full set of electronics just burning a hole in my pocket
Planning to stick the OS in either a Raptor 60 or 90 chassis.
Leaning toward a 90 chassis, just to keep from upgrading later.
Assuming 680 TT carbon blades, what ratio should I be running?
Would like to get about 1900 or so on the head in idle up.
The stock 9.3 gears on the R60 seem a bit high for an OS70?
8.5 on the R90 would give me 16.5 on the motor for 1950 on the head.
Does that sound about right?

Jim Senicka
Team Manager, GrandRC Flight Team

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02-12-2006 09:18 PM  12 years agoPost 2
DOKEY

rrProfessor

Northamptonshire UK

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States here that the OS70 produces 2.5 bhp at 16000 rpm http://www.osengines.com/engines/osmg1972.html

8.5:1 sounds about right then, been a while since using a 60/70 engine, so maybe way out
(Edit!)

Ryan.

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02-12-2006 11:51 PM  12 years agoPost 3
ESWLFSE

rrElite Veteran

Liberty Hill, TX

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I used 9.1:1 on my 70. You want it just above the powerband so that it makes more power when it bogs and not less.

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02-13-2006 06:17 AM  12 years agoPost 4
BlakeMcBrayer

rrElite Veteran

Georgetown, Ky

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I agree with Altimat. I like to have my headspeed slightly above the power band as well.

.

Don't come off the throttle untill you see your GOD!

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HomeAircraftHelicopterThunder TigerOther › R60/90 and OS70SZ gearing
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