stick shake

[adrian_clince]

heys guys -i got a set of gery goodwin blades beautiful set - but there is a stick shake

[danny]

g"day adrian....this is what I do & it seems to sort it out. Get the machine into the air up a bit so that there"s a bit of room and then reduce the forward speed to as close to zero as you dare... don"t go backwards or tail slide, and then see what is happening with the stick as the gyro descends. Keep a bit of power on so that the rudder still works. At no air speed the teeter does nothing and so the straight static balance and weight differences between the blades is apparent. if she"s shaking under this stopped set-up then you need to take the blades and bar down and balance it all. Put it back and go again repeat the process at zero airspeed...get it right add a small bit of weight at a tip, mark the blades and hub bar so that it all goes together the same way every time you de-rig & rig, screw or fix the weight somhow so that it can"t spin off and hit something or some one, probably a good idea...Then go forward at say 40- 50knots and if the stick then shakes a dynamic problem exists, IE the blades don"t fly the same way and so I shim 1 blade with a thin bit of coke can, pick anyone at first, and try it. A bit of trial and error but it seems to work for me. I half expect the boffins to shoot this idea down, but there you go. Let"s know what happens.Danny camel

[louww]

Adrian, chk the clearance between the side of hub bar to inside face of the tall tower. If ya using rosco rotor head, oil the cotton reels prior installation. Test it on the ground by pre rotating to 100 rpm into the wind without taking off and feel for any shake. There bound to be some stick "2 beat" pulse. Gerry"s blades are usually well balance and should not be a problem. Do the simplest chk prior fiddling with blade balance. Keep it simple initially.

[bones]

If ya using rosco rotor head, oil the cotton reels prior installation. Serious question here, why do you oil those bushes they are designed to run dry, i got about 700hrs on a set now, and no movement in them, and they never seen oil or grease.

[bones]

g"day adrian....this is what I do & it seems to sort it out. Get the machine into the air up a bit so that there"s a bit of room and then reduce the forward speed to as close to zero as you dare... don"t go backwards or tail slide, and then see what is happening with the stick as the gyro descends. Keep a bit of power on so that the rudder still works. At no air speed the teeter does nothing and so the straight static balance and weight differences between the blades is apparent. if she"s shaking under this stopped set-up then you need to take the blades and bar down and balance it all. Put it back and go again repeat the process at zero airspeed...get it right add a small bit of weight at a tip, mark the blades and hub bar so that it all goes together the same way every time you de-rig & rig, screw or fix the weight somhow so that it can"t spin off and hit something or some one, probably a good idea...Then go forward at say 40- 50knots and if the stick then shakes a dynamic problem exists, IE the blades don"t fly the same way and so I shim 1 blade with a thin bit of coke can, pick anyone at first, and try it. A bit of trial and error but it seems to work for me. I half expect the boffins to shoot this idea down, but there you go. Let"s know what happens.Danny camel Sounds like a fairly straight forward

[adrian_clince]

thanks guys - i will try a couple of things - i have checked the spacing up top between the hub bar and teeter towers and got it closer to the middle than what it was - it seemed to be alot more one side then equal on both sides - so now its a blade balance ill check that out next time i go flying .- but i do wish it was the case that i could just pull a set of blades out and now have to touch them cheers adrian

[Greg Mitchell]

G"Day Adrian,Are they new? I like Danny"s suggestions.Bones and Birdy have sets that fly smooth as straight out of the box.

[adrian_clince]

- the blades are new - "the hub bar is a matching set to the blades -i think ill try a couple of small things before assesssing things further but thank you guys for your help most appreciated cheers adrian

[bones]

Adrian, one other thing i spose you have tried, but turn them 180* in the head if it is worse then it may be side ways if it better shim it that way, i would near bet it is in the head not the blades, my heads are as close to perfect as i can get them, i can swap blades between machines and they are still smooth.

[asra]

do all rotorcraft experience a tiny stick shake or can u get em so there is no feedback through stick?i have never flown one but am thinking of building/buying one to learn on

[Greg Mitchell]

Adrian, one other thing i spose you have tried, but turn them 180* in the head if it is worse then it may be side ways if it better shim it that way, i would near bet it is in the head not the blades, my heads are as close to perfect as i can get them, i can swap blades between machines and they are still smooth.Yeah what Bones says there is spot on Adrian. Think it was Bones or another one of the fellas told me that when I had a set of a Patroney"s I still have, turned it 180, improved things and then centered the hub bar better and they flew smooth too.Ring Gerry. There new, let him know he will have the best idea.I"ve never shimed Aerodynes but with the round pillar block (bit of an oxymoron) and central single bolt they should be easier to get right than a square block setup with multiple bolts.Good Luck.

[louww]

Adrian, it would not be advisable to eyeball the clearance (if that was what you have done). To use a machinist feeler gauge to determine clearance will be the best bet for checking. Next, you may want to inspect the tower for "leaning tower of pisa", ie, if you are able to see latter through eyeball, than, the tower may have been crooked and probably need to "coke can" shim at base for perpendicularity. Alternatively, a tell-tale sign will show on the teeter block mating surface with the cotton reel impinging mark(s) on other either side after several hours of operation, ie, if the vibration that has caused by the tower.It is interesting that different school of thoughts occurred in oiling cotton reel bushes. My initial understanding that the self lubricated bush should be free from external oiling as suggested by Mark B. but in reality a virgin bush, technically, after it"s been "rockn saddled" by rough rider for many hours eventually will seize to function properly thus preventing the cotton reel to rotate freely as intended. Otherwise, you"ll discover the teeter bolt to rotate instead of the cotton reels and that will not be good. That is why, a good preventive maintenance to inspect cotton reels, clean and lubricate every 25 hours to ensure operation reliability is a better choice (in my opinion). Changing out the teeter bolt and castle nut every 100 hours is my preference.

[tonydenton]

adrian, i wouldn"t be wasting time or risking trying to screw milli-weights to any of gerry"s rotors, a lick of paint maybe.[ only as a last resort] easiest one to check is the sideways clearance in the tower. i actually hate shims, [seem so pre world war 1] i took my cotten reels out and back to town and remachined the faces. left side / right side about 2 to 3 thou. or it could of been right side / left side.

[adrian_clince]

thank you guys again - get more than enough answers - and to be think of it - the paint has started coming off so tony - love the idea to put paint on it - so thats what i will do i thinks what was the best paint for it ? i know the towers are good i used a wedge to get either side close to the center with maybe 1-2 thou movment and then shimmed the cotton reel - i think it was the left side.. and it worked a treat until this back and fourth stick shake come to play - so it maybe blade balance - a lick of paint might just do the trick .p.s i think someone sugested paint earlier on so credits to that fella but again thanks for the input guys most appreciated cheers adrian

[birdy]

Blade mass imbalance gives a rotory shake.Back n forth is more likely "out of cone". [ and changes with load]Dont put any wet lube ona Rosco teeter bolt bush. [ its designed to be dry, so it dont attract dust]