Main rotor and Tail rotor balancing on Hummingbird
07-25-2003, 04:53 AM
#1
Member
Thread Starter
Join Date: Jul 2003
Location: .,
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
Main rotor and Tail rotor balancing on Hummingbird
I found lots of stuff on balancing rotors while searching, great information. I just wanted to humbly pass along my experience on balancing my rotors on the HB. It might be useful to any newbies like me who dont have other methods of balancing.
My main motor just died, so I took it out. I noticed that when the rotor wasnt engaged on the motor, the rotor could spin smoothly and forever it seemed. This thing seems to have some good ball bearings!
Anyway, I decided that this might present a good opportunity to really balance the rotors well. I centered the blades, removed the flybar paddles, held the HB so its rotor was perpendicular to the ground, and spun it slowly a few times (make sure your controls are centered so there isnt any swashplate drag). It was real easy to find the heavy blade since it was pretty consistently stoping on the bottom. With a little tape on the light blade, and a few more spins it was balanced quickly. I put on the paddles again, and respun to make sure it was still ok.
Then I moved on to the tail rotor. I loosened the motor so I could disengage it from the gear. Man, was that tail rotor unbalanced! I think I nailed the source of a shimmy I had on spin up, right before becoming airborn. After a few minutes of spinning and taping it appeared balanced. I reengaged the motor, tightened it down, put the battery in, and spun it up to maximum tail rotor speed. It was solid as a rock!
Unfortunately I have not been able to test the main rotor under power yet since I'm sans a main motor. But I dont expect any surprises. I'll update you guys when I'm back in the air.
My main motor just died, so I took it out. I noticed that when the rotor wasnt engaged on the motor, the rotor could spin smoothly and forever it seemed. This thing seems to have some good ball bearings!
Anyway, I decided that this might present a good opportunity to really balance the rotors well. I centered the blades, removed the flybar paddles, held the HB so its rotor was perpendicular to the ground, and spun it slowly a few times (make sure your controls are centered so there isnt any swashplate drag). It was real easy to find the heavy blade since it was pretty consistently stoping on the bottom. With a little tape on the light blade, and a few more spins it was balanced quickly. I put on the paddles again, and respun to make sure it was still ok.
Then I moved on to the tail rotor. I loosened the motor so I could disengage it from the gear. Man, was that tail rotor unbalanced! I think I nailed the source of a shimmy I had on spin up, right before becoming airborn. After a few minutes of spinning and taping it appeared balanced. I reengaged the motor, tightened it down, put the battery in, and spun it up to maximum tail rotor speed. It was solid as a rock!
Unfortunately I have not been able to test the main rotor under power yet since I'm sans a main motor. But I dont expect any surprises. I'll update you guys when I'm back in the air.
07-26-2003, 05:08 AM
#2
Member
Thread Starter
Join Date: Jul 2003
Location: .,
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
Main rotor and Tail rotor balancing on Hummingbird
I have a century 370 motor on order at my LHS, but I couldnt wait and bought a stock motor that they had in the store. Hopefully this one will keep me in the air until the other arrives.
I was able to fly it today and test the balance. It still has a slight shimmy as it moves through the lower RPMs, but by the time it is ready to hover the bird is noticably smoother. It even seems quieter now.
I was able to fly it today and test the balance. It still has a slight shimmy as it moves through the lower RPMs, but by the time it is ready to hover the bird is noticably smoother. It even seems quieter now.
07-26-2003, 01:05 PM
#3
Member
Join Date: Mar 2003
Location: Kenmore,
WA
Posts: 78
Likes: 0
Received 0 Likes
on
0 Posts
Main rotor and Tail rotor balancing on Hummingbird
One thing I did differently was balance the flybar paddles before I balanced the main blades. Remove the main blades then check the balance of the remaining assembly. Once satisfied, replace the main blades and repeat the balance procedure.
07-26-2003, 05:20 PM
#4
Member
Thread Starter
Join Date: Jul 2003
Location: .,
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
Main rotor and Tail rotor balancing on Hummingbird
Originally posted by kenru
One thing I did differently was balance the flybar paddles before I balanced the main blades. Remove the main blades then check the balance of the remaining assembly. Once satisfied, replace the main blades and repeat the balance procedure.
One thing I did differently was balance the flybar paddles before I balanced the main blades. Remove the main blades then check the balance of the remaining assembly. Once satisfied, replace the main blades and repeat the balance procedure.
07-29-2003, 03:11 PM
#5
Member
Thread Starter
Join Date: Jul 2003
Location: .,
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
Main rotor and Tail rotor balancing on Hummingbird
Have'nt had a chance to rebalance my flybar independently yet, but I think I nailed the source of my shimmy... Plain and simple, it looks like it's the main rotors not being perfectly centered. The shimmy stops when there is enough rotational force to straighten them. If I take the time to adjust them as perfectly as I can before spooling up, the shimmy is minimized.
There are still slight vibrations left, but I think it may be due to a slightly bent shaft, or possibly some of the rotor head pieces not being drilled perfectly on center ( I see a slight wobble at the top of the rotor head as it spools up). Those vibes dont seem enough to worry about though...
There are still slight vibrations left, but I think it may be due to a slightly bent shaft, or possibly some of the rotor head pieces not being drilled perfectly on center ( I see a slight wobble at the top of the rotor head as it spools up). Those vibes dont seem enough to worry about though...
