Stretched Trex600 for 620 blades Project

[barney]

Now that we have the big block engines some folk might be looking at moving to longer Main blades to soak up some the extra power.

This is a little project I have been playing around with. The NovaRossi 57 and Outrage 57 Muffler offering fantastic torque/Power I felt the Std 600 bladed Trex was was overpowered but unable to utilise all the Extra go.

Firstly I modded the mixing.

Initially I modded the Upper Mixing arms (using the Plastic SF Levers) This allows us to increase both the Main and Cyclic pitch Range.

note:- These plastic SF levers have a small amount of Give and are a nice weakpoint in a crash saving servo gearsets, lower metal levers etc. The other nice feature is the small amount of flex acts as a little extra insurance should you bind the head by accidently bunging the TX stick into the corner. This Mod gives a Healthy 15deg Pitch and oddles of Cyclic giving nice POP and sharpens response no end.

To get the best from this and avoid mild blade cavatation in sharp Stops I felt it still needed to run a very high headspeed with some 600 blades..a bit higher than I prefer.

Next Mod was to increase the the Disc diameter by utilising 620 's as it allows the same blade tipspeed but at a slightly lower RPM. This also shifts more air .

One concern was possible main blade/tail blade strikes with the 620 mains and std boom length so I replaced the 600 item with a Trex 700 Boom/TT cut down to clear the tail blades. The additionial bearing on the 700 TT was retained and the Align boomstays were substituted for longer Raptor Items for better support.

The longer boom I think also enhances Piro Manouvres and overall the Trex now flys like a bigger model coping better with windy conditions. Its midway between a frantic 50 and a 90 in feel.

I initially was running the NR57 on the NR dedicated pipe but changing to the Outrage 57 pipe. I think makes for a much happier combo. Torque is better, tuning is easier and Power is well, awesome for a 50 class.

The NR57 is now shimmed for 30%, (It seemed over compressed on the NR pipe when set for 20% Nitro and it reduces its harshness making for an easier tune) OS No 8 but running Optifuel 20% SAB620.s

Although the Vid is nothing special I think its good enough to see its capability. Whilst its not for everyone I think it a worthwhile experiment.
The only drawback is a minimial rearward C&G shift to the rear but still acceptable.

I actually have a 2nd 600's on the NR57 combo, the other is running the 600 blades/boom/modded mixers and yes its awesome too..but my overall Fav is the long blade setup..


cheers Brian

[ame="http://www.youtube.com/watch?v=3GHhcJ3gcjQ"]YouTube - Trex 600 NovaRossi 57 Outrage muffler 620 Blades[/ame]

[moyesboy]

Is the boom longer than a rappy titan?
Is there really a boomstrike possibility with the 620s?or just a fear... or more a problem of the tail letting go?

[mattie-lodge]

Nice write and nice flying Barney.

I've just put my YS 56 in my raptor. I might also consider puting the longer blades on aswell.

Thanks for sharing this info

[barney]

Not sure TBH on a Rappy Boom length.

Initially I also considered the a possibility of having to try running longer Tails than 95mm as 620's will have more torque to be overcome by the tail.

Using 600mm blades you have about 10-15mm clearance depending on Main/Tails used.

With 620's there is an overlap. As I had a Velocity so used the basis of that as the Mainshaft to Tail output shaft as the length for clearance since it accepts up to 630's.

[barney]

Not sure on your Titan for boom length there Matt. They were stretched from R30 to the 50.
Its easy to check on any model. Just spin the head till the tails/ Main blade tip are closest and Flex the blade down. In practice the flex should be less due to the rotationial forces but I would Maintain a similiar clearance to a std setup if in doubt

[mattie-lodge]

Will check, I'm pretty sure one of the mods for the Titan was a longer boom to accept the longer blades, but will check first.

[Tim Procter]

Will check, I'm pretty sure one of the mods for the Titan was a longer boom to accept the longer blades, but will check first.

It was Matt. The Titan and the v3 deffo has the longer boom.

Nice flying Brian.

[barney]

Just thought I would post a picture of how to modify your upper mixing arms if your looking to extract every last bit of Pop and Power from a big Block Trex 600N.

I think this pic originally came from Ade Law. Best read my first post talking about using the Plastic upper SF levers rather than metal. Be aware there is some binding at the extremes depending how much of the increase in travel you opt to use. Plastic levers are about £7 so not the end of the world if its not to your taste.

Enjoy