Ultra Sport40( elevator's resonance)
03-15-2004, 06:07 AM
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Ultra Sport40( elevator's resonance)
I completed the Ultra Sport 40 from kit. Engine is OS70 4 strokes. All construction and linkage were built straight according manufacture instruction. The props were balanced with Graupner balancer.
The problem is resonance of the elevator on RPM close by to middle range or a lit bit slowly. The throttle steak is near vertical position. This resonance takes place in the air and on the ground as well. High-speed flight is with out problem and with out flatter. The control linkage is tight.
I tried to do with out any successes follows:
1. I closed the hinge gap with scotch;
2. I changed the weight of the elevator with strips of insulation tape.
3. I changed the props.
4. I disconnected the push rod from elevator.
I see one way now. But this way is cut some lightenings in the elevator to change the point of resonance.
I want to ask your opinion about it or some advises.
The problem is resonance of the elevator on RPM close by to middle range or a lit bit slowly. The throttle steak is near vertical position. This resonance takes place in the air and on the ground as well. High-speed flight is with out problem and with out flatter. The control linkage is tight.
I tried to do with out any successes follows:
1. I closed the hinge gap with scotch;
2. I changed the weight of the elevator with strips of insulation tape.
3. I changed the props.
4. I disconnected the push rod from elevator.
I see one way now. But this way is cut some lightenings in the elevator to change the point of resonance.
I want to ask your opinion about it or some advises.
03-15-2004, 02:53 PM
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RE: Ultra Sport40( elevator's resonance)
Everything vibrates at a given pitch. Your plane vibrates at the frequency that the engine is putting out at that particular throttle setting. About the only thing you can do is to avoid flying for prolonged periods at that RPM.
If the Vibration takes place at a throttle setting you like to cruise at, try switching to a different prop. It may still vibrate, but hopefully it will do it at a different throttle setting.
Switching to a soft mount can also help the problem.
If the Vibration takes place at a throttle setting you like to cruise at, try switching to a different prop. It may still vibrate, but hopefully it will do it at a different throttle setting.
Switching to a soft mount can also help the problem.
03-15-2004, 08:03 PM
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RE: Ultra Sport40( elevator's resonance)
Yury,
My .60 size does the same as you describe and so did my .40. Like MinnFlyer says, everything has it's range of vibration. I have had my .60 for over 5 years (bought it used, so god only knows how old it really is) with no problems to mention.
Go ahead and shove the stick to the firewall. It really likes to fly FAST!
My .60 size does the same as you describe and so did my .40. Like MinnFlyer says, everything has it's range of vibration. I have had my .60 for over 5 years (bought it used, so god only knows how old it really is) with no problems to mention.
Go ahead and shove the stick to the firewall. It really likes to fly FAST!
03-16-2004, 11:04 AM
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RE: Ultra Sport40( elevator's resonance)
I tried two props 11x9 and 12x8 with out any changes. I work with throttle a lot. Engine pasts through this setting very often. The 4 CA hinges from 6 on elevator were broken. I replaced they for Do-Bro hinges. I am afraid that this resonance can destroy or elevator or hinges or elevator or clevis. I want to avoid this unwanted vibration completely.
