chinese weight, anyone tried ?

[neohp]

Hello freaks

Did anybody try the chines weight mod that is well used on the trex 450 ?
I'd like to know if it will do any good on our hurri...

Please let me know !

[mjdee14]

what is it.....do you have a link?

[JaggedEdge]

http://www.helifreak.com/showthread.php?t=41309

[kahn10]

http://www.youtube.com/watch?v=XWkQGFaArzg
check this one out the guy has a meter showing the forces........
and yes works on any heli and standard on a lot of full size ones apparently.weight redistribution changes the forces acting on the tail rotor from a flat plane pushing against air pressure created by its own velocity to a sphere rolling against it.....kind of

[Wazzer]

Its a very beneficial mod to all model helicopters

if setup properly it can reduce the force the tail servo has to apply by a factor of about 6

Can reduce current draw quite considerably leading to longer flight times from Rx batteries etc

Will also be able to lower Gyro gain and make the whole tail assembly work much less hard.

In theory these weights would also work on the main blade grips but im not volunteering to test that one out!!

Check out the pics to see what they look like on a Trex600 as it would be very similar for our Hurricanes.

I prefer the Fireup tail mod on the Trex450 as they are screwed on separately directly to the blade grips and not to the tail blade bolts so you can change blades easily and not mess up your adjustments.

To test you simply remove main blades clamp heli to bench disconnect tail servo from pushrod. Leave tail blades on.
Spool up the heli to hovering speed then by hand CAREFULLY move the push rod and feel the force required to change tail blade pitch to both extremes
Add the weights and repeat test adjusting the bolts and weights until the push pull force feels neutral through out the range.

If you get it wrong it will increase the force required to change the tail blade pitch and not reduce it as desired

PLEASE PLEASE BE CAREFULL WHEN ATTEMPTING THIS TEST

I may well do this to my heli soon (when i have the time) and if i get good results I will of course share my findings.

[mjdee14]

So... if I reason this out....when you apply tail rotor and the blades come out of neutral it's like a barn door in the wind...the leading edge catched the wind and wants to be forced to full pitch. Kind of like when you have your hand out the window doing 60 mph or ?kph...and you make it go up and down.

The weights don't like being off center and centrifugal force is always trying to bring them back to center.....when done properly the weights offset the airforce and yu get a neutral action....

Pretty slick....I am sure this would really help the gyro do it's thing.....


Wazzer..thanks for the pics with it on the tail bolts.....would never have thought of that...

[neohp]

i'm gonna try this, i was just wondering if someone already done that, so we could share experience : weight, distance from the hub etc....

So don't hesitate to post any progress !

[mysticmead]

DO NOT do the mod like fireup did unless you have metal grips. drilling a hole to add a weight to plastic will weaken it and can cause the blades to fly off. If you have plastic grips, and want to add the weights. add them to the bolt that hold the tail blades on.

[mjdee14]

DO NOT do the mod like fireup did unless you have metal grips. drilling a hole to add a weight to plastic will weaken it and can cause the blades to fly off. If you have plastic grips, and want to add the weights. add them to the bolt that hold the tail blades on.

Good warning.....I might have been tempted to drill the plastic trex grips....

[kahn10]

kind of mike.in a physics way when your tail rotor is spinning its forces are basically a mass acting in a single plane.any changes in its line of action even without taking air pressure into account your making it fight its own inertia,thats why lighter tail blades help lessening that inertia.with the chinese weight mod your changing the forces acting on your tail to something more like a rotating ball so no matter what input it gets it's in balance - with no inetia created by its mass.like ben said it could also be done to your main blades but i think that would negate to some degree the gyroscopic effect......be like a heli on "ice" :shock:

[neohp]

For sure i wouldn't drill a plastic grip. I've the gaui cnc and i'll start by adding weight on the tail screw. to start...

[Wazzer]

NO absolutley DONT drill and tap the plastic grips!!

Its also very hard to get that right without a special Jig
Fireup sells a jig but it only fits std Trex 450 size tail blade grips.

Its a pretty simple idea so you could easily make a jig for the larger 500 class helis with Aluminium if you had your own mill or a tame machinest local to you.