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HomeAircraftHelicopterAlignT-REX 600N › Alternative gear ratio wanted circa 8.7
10-22-2009 04:33 PM  8 years agoPost 1
Barney

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Inverness Scotland

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Anyone know a way to alter the ratio for a Trex 600N. Or parts that can be used to allow a change to about 8.7

thanks Brian

SPARTANRC Team pilot

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10-22-2009 07:13 PM  8 years agoPost 2
QuantumPSI

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Atlanta, GA

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An 8.7 ratio would be AWESOME!

...now where was I, dh/dt = BS-dx/dt
I will fly you forever... till earth do us part

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10-22-2009 08:55 PM  8 years agoPost 3
mont_blanc

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UK

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I can't swear to this, as I never got round to this modification before selling my trex 600, but...:

The Hirobo Scedau has an 8.7 gear ratio and the clutch bells are the same size. You'll need to buy either of the following:

Scedau Parts Needed

Option One:

Main & Auto Gear + Hub & Oneway bearing.
bottom gear off vertical post for tail drive
Clutch Bell

Option 2:
As Above plus:
Clutch Shoe
Fan
Fan Hub

If you need to go for option 2 you'll need a starter shaft with a one way bearing in it.

I decided to swap my 600 for a 700 and kept my scedau as it has so much torque and power in comparison to the 600, albeit heavier and slightly less agile.

The Sceadu main gears are a little noisier unless you buy the expensive delrin ones.

Bear in mind you may also need to change you pipe. (I found the zimmermann pipe the best at this gear ratio)

hope this helps.

fly a rubber heli - it's cheaper!

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10-22-2009 09:00 PM  8 years agoPost 4
Wingman77

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Pulaski Tennessee

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the vibe also has that ratio.

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10-22-2009 10:40 PM  8 years agoPost 5
Barney

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Inverness Scotland

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Thanks guys..was kinda hoping an alternative pinion/main gear was available

The reason for this is the Velocity with the Novarossi 57 runs sweeter on the optionial 8.7 gear ratio with a few more RPM on the motor.

I'm fitting out my 600N and going to stretch the boom a little (T700 boom and a spare Velocity TT)to accomadate 620's and plan turning it at 2100. I also might want to increase the tail blades to 100mm with the longer main blades.

I'm thinking this will give an ideal balance between Pop and torque.

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10-22-2009 11:26 PM  8 years agoPost 6
Andy_Johnstone

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Liverpool - England

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if you find out brian let me know ive been wanting to do it to mine for ages but never figured it out

Optifuel, NHP, Revolution Models, CSM Team pilot 2011

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10-23-2009 12:10 AM  8 years agoPost 7
mont_blanc

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UK

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Sounds likes there's possibly a market for one of the after market manufacturers (or Align) to make an optional part.

fly a rubber heli - it's cheaper!

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10-23-2009 02:48 AM  8 years agoPost 8
jasnlemons

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upstate, SC United States

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Only prob is that it takes the os engine out of its power range. I had the vibe at 8.70 and wanted it at 8.5 due to having to run the motor so hard. Just my 2 cents.

Fly it like you stole it!
Stick Banging Expert

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10-23-2009 09:20 AM  8 years agoPost 9
Barney

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Inverness Scotland

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Not sure I agree with you jas. The OS 50 on 8.5 at 2100 its turning 17850 on 8.7 = 18270 which is still well within spec. It runs very well at 8.7 BTW with a good pipe.
OSH50 Practicial RPM 1600-20000 it does claim 1.9hp at 17500 no mention of Max Torque. BTW the os55 lists the same RPM's except 2.1hp at 17000 as above

Anyways this is a Novarossi57 which can run as high as 21000 Rpm's Max Power is 2.4hp at 18500 RPM. We have already run the motor on the 8.7 ratio and know it works very well indeed.

On 8.7 its turning 2126 at 18500Rpm..It holds a very constant Headspeed under load. I prefer to keep the Headspeed around 2100 although there is potentially more headroom should you want a little more even on 8.7 (This motor is a beast power wise)

Untill the new generation 50,s came along 600 blades were the biz but now we have the power its time to move on.

Its the blade TIP speed thats important.

The bigger blade provides more thrust before reaching stalling angles + Running 620's at 2100 should reduce blade cavatation as you travel through your own rotorwash. (Thats why 90 size helis stop so cleanly ..big disk area)

Brian

SPARTANRC Team pilot

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10-23-2009 02:03 PM  8 years agoPost 10
jasnlemons

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upstate, SC United States

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I agree. The novarossi motor would be better. It was just that my O.S. motor seemed to Scream at the top Rpm to get it to pop. It could have just been the motor. It just did't seem to like it there. Higher RPM and when it got loaded it would die. Probably the ring.

Fly it like you stole it!
Stick Banging Expert

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10-23-2009 05:41 PM  8 years agoPost 11
ady

rrKey Veteran

norfolk england

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http://www.infinity-hobby.com/main/...hp?cPath=32_126
infinity hobby have a selection of pinions for the rex 600 , hope this helps

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10-23-2009 08:35 PM  8 years agoPost 12
Barney

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Inverness Scotland

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Thanks Ady..the sizes are running the wrong way

SPARTANRC Team pilot

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10-23-2009 09:52 PM  8 years agoPost 13
ady

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norfolk england

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sorry dude , was worth a try i suppose

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12-19-2009 06:26 PM  8 years agoPost 14
John Benario

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Las Vegas

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See my new post

John Benario

Team highest quality
Futaba radios
Cool Power fuel
John's Ultimate building school

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HomeAircraftHelicopterAlignT-REX 600N › Alternative gear ratio wanted circa 8.7
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