Slinging the Blades

GyroChuck

Gyro's are more fun
Joined
Oct 30, 2003
Messages
3,961
Location
Naperville, IL
Aircraft
SnoBird Tandem Gyro, Robinson R-22, Mosquito XE-285, Assorted Fixed Wing
Total Flight Time
2400
At a PRA Convention years ago. Rusty Nance was helping me to get the stick shake out of my blades. He mentioned about trying to sling the blades.

This is where you loosen up the blade bolts just a bit. Then spin up the blades to let them seek their own path. Then let them spin down with out touching them. When stopped, tighten the blade bolts again. Of course you want to do this on a calm day.

Since I was trying this with the gyro parked and just using the pre-rotor. I could not get them spinning fast enough.

Has anyone else tried this and does it help.

I have a Mosquito helicopter that I would like to try it on. I could just hover with the blades at full RPM land and let the blades slow down and stop on their own. I know the blades are in balance because I have two different electronic levels and the both read the same.
 
I would like to hear how it works out. I can envision some undamped cyclical seeking in-plane (lead-lag motion) that might not produce a single spot solution. It's unclear to me that when it spins down it would be at the optimum average, but I am open to learning from the experience of others.
 
How are you checking blade weight @GyroChuck
Overall weight and end for end
 
Last edited:
How are you checking blade weight @GyroChuck
Overall weight and end for end
Have not checked blade weight. I am using the blades that came from the manufacturer.
 
It is somewhat standard on model gyros to only attach the blade root to the grip with one bolt that allows the blade
to rotate, but is tight enough to provide some resistance, like a soft clutch. this allows the blade to always find center and usually saves the blade
when you roll over.... Also allows easy folding for transport
I have wondered if that would work for full scale......
 
I have wondered if that would work for full scale......
I wonder about that also.

With the newer blade manufacturers lead/lag does not seem to be as large problem.
 
I’ve alway slung my blades…..you slightly loosen the blade strap bolts….pick a calm day and spin them up to flight speed which includes a runway run until the rotor is completely coned …..even up to when the nose wheel lifts off…..then…the important part…….flatten the rotor disc and slowly exit the runway and stop with no abrupt movements of the stick……let rotor spin down to stop with disc remaining level…….then…..carefully tighten strap bolts.

I prefer slinging over stringing……both are good methods……I feel slinging helps the blades find their own true center. 😊

Fly safe 😎
 
Do you loosen both blades, or just let one sweep to suit a fixed blade?
 
I wonder about that also.

With the newer blade manufacturers lead/lag does not seem to be as large problem.
The root shape and the fit into the grip could provide a limiting stop, although I was thinking it would be great to make the stop removable so the blades could be folded.... The grip area would have to be larger and provide adequate friction surface....
I have a set of blades and head (Thanks Jim) that I plan on using as an experimental platform, so this may become an experiment.
I think an adapter could be made that would bolt to the blade with the standard bolts and then fit into a grip adapter that was the single bolt design. It would add about 12" to the blade span, so the hub bar would need to be shorter to maintain original span. I could see this as a hub bar that comes with grips to fit any blade as an aftermarket item........
 
Perhaps an effective slinging method of balance could be achieved by using a stationary rotor spinning stand with ample power to spin the rotor to flight RPM. This could be performed outdoors with calm air or inside an ample sized hanger with the doors closed. A much safer method in a controlled environment.

Wayne
 
I've just finished setting up two sets of blades. The first are original Mosquito Air blades on an original Mosquito head, while the second are Gyrotech blades on a smaller version of a Mosquito head.

With both I clamped an 80cm long level to the teeter plates and adjusted lead/lag so that the gap between the level and the blade stayed constant. An adjustment of 1/12 of a turn on the adjustment screws makes a surprising large difference.

Both sets of blades spun up nicely with minimal vibration. I'm flying the original Air and have got airborne with the new head without having to do any further balancing.
 
I've just finished setting up two sets of blades. The first are original Mosquito Air blades on an original Mosquito head, while the second are Gyrotech blades on a smaller version of a Mosquito head.

With both I clamped an 80cm long level to the teeter plates and adjusted lead/lag so that the gap between the level and the blade stayed constant. An adjustment of 1/12 of a turn on the adjustment screws makes a surprising large difference.

Both sets of blades spun up nicely with minimal vibration. I'm flying the original Air and have got airborne with the new head without having to do any further balancing.
Interesting. Do you have a photo of the newer Mosquito head. Is it pretty straight forward on how to replace the old head?

On my Mosquito Straight and level. Vibration is not too bad. But when I lower collective to descend. I get a pretty bad cabin shake. I have tried various airspeeds (40-65mph) when descending and have the same result.
 
Just because the blades are new that does not men the weight is perfect! Check them!
 
Questa è la nuova testa, un po' più piccola e molto più leggera della testa Mosquito originale. La testa originale pesa 18 kg, questa è 13 kg. Adesso renderà facilmente il peso ultraleggero, comprese le batterie.

L'albero principale è in titanio, i controlli sono tutti in carbonio.
View attachment 1160065
Mah è an electric model?
 
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