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HomeAircraftHelicopterThunder TigerOther › converting my r75 to a r90
04-28-2004 11:35 AM  14 years agoPost 1


lincolnshire uk

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hi just wondered if anyone know's if putting an os 91 in my r60 would be ok .i have a webra 75 aar in it at the moment and its a bag of kak, i'm already using 8.45 gearing and a carbon base plate just wondered if would get away with 68cm blades and no frame stiffener, obviously if i got a c spec i would need the new cooling tunnel and servo frame.


04-28-2004 12:07 PM  14 years agoPost 2


Hampshire Sponsored by Quick UK

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You can use the 680 blades, if using the os change the gear ratio to 8.27, The standard clutch does work but it will wear out.
If your handy with a dremel you can modify the fan housing and radio tray in 5 minutes.

I've been using my setup for a year and a half, it now uses the c-spec ps, heavy duty clutch,8.27 ratio, muscle pipe2 and 680 blades with standard lenght boom.

Have fun

Using the ground to reverse engineer

04-28-2004 01:22 PM  14 years agoPost 3

rrElite Veteran

Moline, il

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im using the same setup as daren but i would recommend getting the servo frame and fan shroud for the r 90 as my ps likes to get hot from all you have to grind away. yes do 8.27. this is a nice setup. if you need a c-spec ps maybe we can make a deal as im going to try a ys. my motor is not broke in all the way but i like to try new things all the time. pm me if you need pics of anything.

04-29-2004 12:07 AM  14 years agoPost 4

rrKey Veteran

Inverness Scotland

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I'm using the 8.27 ratio.. MP combo OS C spec PS..with 680's but using TJ to limit head speed. I'm running +10 -10 with straight fuel. I fitted the 90 servo frame/fan's only £20ish the tail drive shaft & add 2nd drive shaft bearing to reduce vibs.
Highly recommend the base plate for crash resistance not only for the stiffness..also highly recommend the larger 90/3D clutch. Go with stiffer head dampers ..still working on that one as the 80 duro ones I,ve tried wear very quickly. The new 90 plastic head block has an alloy sleeve where it fits on the mainshaft to reduce rocking again its only slightly more than the std one.

Boom..I have just changed to the longer boom setup so I can fit longer tails but not essential..I think it is only about 40mm longer anyway.

I would/did fly it as std till U break the boom etc ( I had a catostrophic mid air boomstrike) either a link or boom let go at main frame not sure.

Maintenance is a bit higher theres a lot more torque/power/vibration to consider. Trying to get the 90 started from cold is a B%&$H. Usually I have to unscrew the plug a few turns to start..but once warm no problem & yes it needs a good starter & battery too!!

keep as close to standard till you bend it then fit the 90 parts..Not much more cost. I save in fuel costs by running straight fuel against a screaming 60 on 30% nitro £10 against £30 a gallon in the UK

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HomeAircraftHelicopterThunder TigerOther › converting my r75 to a r90
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