Shaky Jake (32B Engine)
03-13-2008 | 02:32 AM
#1
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From: Monterey,
CA
Shaky Jake (32B Engine)
I have a GP Giant super sportster pulled with a Fuji 32B. It's my first gas setup and will be my last if I can't fix the issue
I have been told the level of vibration is greater with gas...no, really?
On my first flight after run-in, I lost a Aileron clevis (Great planes hardware supplied with the kit) cracked and fell off. Landed safely
Also 3 out of 4 CA hinges busted at the Aileron hinge line. Repaired, Second flight. Lost Aileron servo (Missing teeth) Landed safely, Replaced all Hitec Hi-torque servos with Futaba Metal geared servos.
Third flight, port side clevis failed (Threaded end) , landed safely.
The setup is stock per GP
Prop: Well balanced MAS 18x8 (Turning 6900 static, standard day, sea level)
Fuel: 87 Octane, Lube: Klotz 40 to 1
Spinner: Stock with the kit (Prop and Spinner balanced as a unit)
Prop hub extention TIR .0025" (Radial)
Prop hub extention TIR ..002 (Face)
There are some RPM's I must avoid due to a harmonic vibration that sounds as if she is about to come apart at the seams (3850 - 4500) But HF vibration it always present at all RPM's (Realy severe)
This weekend I'm gonna throw an APC prop on it and see if that helps.
I don't believe its the prop, but its worth a try.
One thing I did not check is the TIR of the prop bolt, you don't think it could have been drilled a little off center?
Do they make an ISO mount for the 32B? I'm willing to take the hit on power for the reduction of vibes....
Best regards
~johnny
I have been told the level of vibration is greater with gas...no, really?
On my first flight after run-in, I lost a Aileron clevis (Great planes hardware supplied with the kit) cracked and fell off. Landed safely
Also 3 out of 4 CA hinges busted at the Aileron hinge line. Repaired, Second flight. Lost Aileron servo (Missing teeth) Landed safely, Replaced all Hitec Hi-torque servos with Futaba Metal geared servos.
Third flight, port side clevis failed (Threaded end) , landed safely.
The setup is stock per GP
Prop: Well balanced MAS 18x8 (Turning 6900 static, standard day, sea level)
Fuel: 87 Octane, Lube: Klotz 40 to 1
Spinner: Stock with the kit (Prop and Spinner balanced as a unit)
Prop hub extention TIR .0025" (Radial)
Prop hub extention TIR ..002 (Face)
There are some RPM's I must avoid due to a harmonic vibration that sounds as if she is about to come apart at the seams (3850 - 4500) But HF vibration it always present at all RPM's (Realy severe)
This weekend I'm gonna throw an APC prop on it and see if that helps.
I don't believe its the prop, but its worth a try.
One thing I did not check is the TIR of the prop bolt, you don't think it could have been drilled a little off center?
Do they make an ISO mount for the 32B? I'm willing to take the hit on power for the reduction of vibes....
Best regards
~johnny
03-13-2008 | 10:13 AM
#2
My Feedback: (11)
RE: Shaky Jake (32B Engine)
First make sure the airframe is strong enough. Some models just need a thicker firewall that's well-mounted onto the airplane. That's one source of vibration. Single-cylinder engines will never be smooth, but always have some level of vibration. There will also be greater and smaller harmonics, depending upon RPM. That's also a given. If parts of the airframe are breaking due to vibration, not only will they have to be replaced with different materials, but the engine may need work.
It's possible that the engine's prop flange is not quite on center. That would need to be checked. Prop and spinner must be balanced. A vibration-isolating engine mounting system can help. Propping the engine for higher or lower RPM at full throttle can help because it will change the modes of vibration. A heavier or lighter propeller may help. The only way to find out is to try things.
It's possible that the engine's prop flange is not quite on center. That would need to be checked. Prop and spinner must be balanced. A vibration-isolating engine mounting system can help. Propping the engine for higher or lower RPM at full throttle can help because it will change the modes of vibration. A heavier or lighter propeller may help. The only way to find out is to try things.
03-13-2008 | 11:06 AM
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From: Monterey,
CA
RE: Shaky Jake (32B Engine)
ORIGINAL: Bax
First make sure the airframe is strong enough. Some models just need a thicker firewall that's well-mounted onto the airplane. That's one source of vibration. Single-cylinder engines will never be smooth, but always have some level of vibration. There will also be greater and smaller harmonics, depending upon RPM. That's also a given. If parts of the airframe are breaking due to vibration, not only will they have to be replaced with different materials, but the engine may need work.
It's possible that the engine's prop flange is not quite on center. That would need to be checked. Prop and spinner must be balanced. A vibration-isolating engine mounting system can help. Propping the engine for higher or lower RPM at full throttle can help because it will change the modes of vibration. A heavier or lighter propeller may help. The only way to find out is to try things.
First make sure the airframe is strong enough. Some models just need a thicker firewall that's well-mounted onto the airplane. That's one source of vibration. Single-cylinder engines will never be smooth, but always have some level of vibration. There will also be greater and smaller harmonics, depending upon RPM. That's also a given. If parts of the airframe are breaking due to vibration, not only will they have to be replaced with different materials, but the engine may need work.
It's possible that the engine's prop flange is not quite on center. That would need to be checked. Prop and spinner must be balanced. A vibration-isolating engine mounting system can help. Propping the engine for higher or lower RPM at full throttle can help because it will change the modes of vibration. A heavier or lighter propeller may help. The only way to find out is to try things.
~johnny
