Vibration dampning mounts?
12-23-2010, 11:33 AM
#26
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RE: Vibration dampning mounts?
vibration damping works much better when the part you are trying to isolate is much lighter than the object it is mounted in, for example motor in refrigerator, engine in car etc.
12-25-2010, 12:47 PM
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RE: Vibration dampning mounts?
It also helps if the reciprocating parts are low in weight in relation to overall mass of the engine and are acceptable to static and dynamic balance.
I once made acceleration measurements on a 0.40 size airplane. I found more than 50gs p-p. Incidentally those little rubber washers the manufacturers mount the servos with do absolutely nothing for you.
I once made acceleration measurements on a 0.40 size airplane. I found more than 50gs p-p. Incidentally those little rubber washers the manufacturers mount the servos with do absolutely nothing for you.
12-25-2010, 03:54 PM
#28
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RE: Vibration dampning mounts?
I have made Hyde type mounts and flexable fiberglass mounts that did reduce airframe noise. They would be difficult to mount on current ARFs because they require a large firewall footprint in order to keep weight down. Any mount that held the engine firmly enough would still put the energy into the airframe. Amplitude is traded for duration which gets rid of noise but little else. Any rubber that is dead enough to absorb energy will get hot. A rubber that stays cool can only average the vibration force. The engine will move more and the airframe less.
12-25-2010, 05:21 PM
#29
RE: Vibration dampning mounts?
I was always going to desigh/make a viabration mouting plate & see how it would work. This could be done 2 or more ways. If the fiewall was fairly large & flat...cut a aluminumplate with 4 studs or bolts to attach engine. I would use a 1/4 thick pad of high quality silicone rubber between the plate & fire wall for the viabration damper. No direct contack of metal. Maybe 4safty catches to hold/stop any to much forward movment if the silicone let loose. This may work up to a 30cc engine. Maybe & maybe not. Just a test would be a step in the right direction. capt,n
12-25-2010, 07:35 PM
#31
RE: Vibration dampning mounts?
Here is a link to a forum that MTK started that has a lot of info on a soft mount:
http://www.rcuniverse.com/forum/m_6285026/tm.htm
The pattern fliers use them mostly to reduce noise, but I have heard they also get a reduction in the amount of current drain on the servos.
http://www.rcuniverse.com/forum/m_6285026/tm.htm
The pattern fliers use them mostly to reduce noise, but I have heard they also get a reduction in the amount of current drain on the servos.
12-26-2010, 07:14 AM
#32
RE: Vibration dampning mounts?
ORIGINAL: Kweasel
I bonded plywood to .5"EVA floor foam with CA to make a light weight isolation mount. It needs to be 6"diameter for a 40-50cc. I have not found anything that bonds to silicone.
I bonded plywood to .5"EVA floor foam with CA to make a light weight isolation mount. It needs to be 6"diameter for a 40-50cc. I have not found anything that bonds to silicone.
01-02-2011, 02:38 PM
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RE: Vibration dampning mounts?
I don't mean to change the current topic of this forum, In fact I find it very interesting Because I have been considering putting a set of B&B's Vibra Loc's on my RCGF 20cc standoff's at the firewall. But the question I have is " Why do RC Gasoline Engines normally have standoff"s? are they themselves the vibration Damper, Isolator, Absorber? Should a Gas Engine without Standoffs (such as The CPRC's and Evolution's) be avoided? Thanks By the Way for the information thus far. Mike.
01-02-2011, 03:23 PM
#34
RE: Vibration dampning mounts?
I would think that if it were really an issue we would see more soft mounts either home brew or manufactured product more in use. Go to any IMAC contest were guys are running anything from 30 to 170cc and count how many soft mounts are in use. My guess would be ZERO. An engine that is well tuned, has it's timing correctly set and is spinning a properly balanced prop and spinner does not vibrate all that much. What vibration you do see on the ground is just that. In the air the airframe does a much better job of absorbing the vibration.
01-02-2011, 05:59 PM
#35
RE: Vibration dampning mounts?
I have a question. I read a few years back that soft mounts on a RC engine may not tranfer the viabration to the aircraftand the result was the vibration then was harm-flull to the engine. Is there nay data to back up that theroy or is it a myth? Thanks Capt,n
01-02-2011, 06:14 PM
#36
RE: Vibration dampning mounts?
ORIGINAL: speedracerntrixie
I would think that if it were really an issue we would see more soft mounts either home brew or manufactured product more in use. Go to any IMAC contest were guys are running anything from 30 to 170cc and count how many soft mounts are in use. My guess would be ZERO. An engine that is well tuned, has it's timing correctly set and is spinning a properly balanced prop and spinner does not vibrate all that much. What vibration you do see on the ground is just that. In the air the airframe does a much better job of absorbing the vibration.
I would think that if it were really an issue we would see more soft mounts either home brew or manufactured product more in use. Go to any IMAC contest were guys are running anything from 30 to 170cc and count how many soft mounts are in use. My guess would be ZERO. An engine that is well tuned, has it's timing correctly set and is spinning a properly balanced prop and spinner does not vibrate all that much. What vibration you do see on the ground is just that. In the air the airframe does a much better job of absorbing the vibration.
01-02-2011, 06:21 PM
#37
RE: Vibration dampning mounts?
ORIGINAL: captinjohn
I have a question. I read a few years back that soft mounts on a RC engine may not tranfer the viabration to the aircraftand the result was the vibration then was harm-flull to the engine. Is there nay data to back up that theroy or is it a myth? Thanks Capt,n
I have a question. I read a few years back that soft mounts on a RC engine may not tranfer the viabration to the aircraftand the result was the vibration then was harm-flull to the engine. Is there nay data to back up that theroy or is it a myth? Thanks Capt,n
01-02-2011, 06:36 PM
#38
RE: Vibration dampning mounts?
ORIGINAL: Joystick TX
Most of the soft mounts seem to be used by the pattern fliers, mostly to reduce noise, reduced vibration is not the main goal.
ORIGINAL: speedracerntrixie
I would think that if it were really an issue we would see more soft mounts either home brew or manufactured product more in use. Go to any IMAC contest were guys are running anything from 30 to 170cc and count how many soft mounts are in use. My guess would be ZERO. An engine that is well tuned, has it's timing correctly set and is spinning a properly balanced prop and spinner does not vibrate all that much. What vibration you do see on the ground is just that. In the air the airframe does a much better job of absorbing the vibration.
I would think that if it were really an issue we would see more soft mounts either home brew or manufactured product more in use. Go to any IMAC contest were guys are running anything from 30 to 170cc and count how many soft mounts are in use. My guess would be ZERO. An engine that is well tuned, has it's timing correctly set and is spinning a properly balanced prop and spinner does not vibrate all that much. What vibration you do see on the ground is just that. In the air the airframe does a much better job of absorbing the vibration.
01-03-2011, 06:36 AM
#39
RE: Vibration dampning mounts?
ORIGINAL: speedracerntrixie
Silly me, I thought vibration is noise......
ORIGINAL: Joystick TX
Most of the soft mounts seem to be used by the pattern fliers, mostly to reduce noise, reduced vibration is not the main goal.
ORIGINAL: speedracerntrixie
I would think that if it were really an issue we would see more soft mounts either home brew or manufactured product more in use. Go to any IMAC contest were guys are running anything from 30 to 170cc and count how many soft mounts are in use. My guess would be ZERO. An engine that is well tuned, has it's timing correctly set and is spinning a properly balanced prop and spinner does not vibrate all that much. What vibration you do see on the ground is just that. In the air the airframe does a much better job of absorbing the vibration.
I would think that if it were really an issue we would see more soft mounts either home brew or manufactured product more in use. Go to any IMAC contest were guys are running anything from 30 to 170cc and count how many soft mounts are in use. My guess would be ZERO. An engine that is well tuned, has it's timing correctly set and is spinning a properly balanced prop and spinner does not vibrate all that much. What vibration you do see on the ground is just that. In the air the airframe does a much better job of absorbing the vibration.
01-03-2011, 08:09 PM
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RE: Vibration dampning mounts?
I actually have some experience with vibration dampening from an engineering and application standpoint and I can assure you done properly, a larger displacement model aircraft would benefit greatly with a properly tuned dampening system. Its not too difficult to make things better with standard type isolators but to get it real good takes some effort. If you have access to an adjustable strobe light with a range of 100 to say 12000 flashes per minute you will be able to do some good tuning. One item of concern with a softer isolator is the throttle linkage (fixed at one point, flex at the other) put a strobe on it and you will see what I mean things move much more than you think.
I personally don’t mess with it on my planes as I’d rather just go fly, I don’t care much about the noise reduction and vibration is rarely what destroys my planes its usually gravity lol.
I personally don’t mess with it on my planes as I’d rather just go fly, I don’t care much about the noise reduction and vibration is rarely what destroys my planes its usually gravity lol.
01-04-2011, 11:31 AM
#41
RE: Vibration dampning mounts?
ORIGINAL: tripower222
I actually have some experience with vibration dampening from an engineering and application standpoint and I can assure you done properly, a larger displacement model aircraft would benefit greatly with a properly tuned dampening system. Its not too difficult to make things better with standard type isolators but to get it real good takes some effort. If you have access to an adjustable strobe light with a range of 100 to say 12000 flashes per minute you will be able to do some good tuning. One item of concern with a softer isolator is the throttle linkage (fixed at one point, flex at the other) put a strobe on it and you will see what I mean things move much more than you think.
I personally don’t mess with it on my planes as I’d rather just go fly, I don’t care much about the noise reduction and vibration is rarely what destroys my planes its usually gravity lol.
I actually have some experience with vibration dampening from an engineering and application standpoint and I can assure you done properly, a larger displacement model aircraft would benefit greatly with a properly tuned dampening system. Its not too difficult to make things better with standard type isolators but to get it real good takes some effort. If you have access to an adjustable strobe light with a range of 100 to say 12000 flashes per minute you will be able to do some good tuning. One item of concern with a softer isolator is the throttle linkage (fixed at one point, flex at the other) put a strobe on it and you will see what I mean things move much more than you think.
I personally don’t mess with it on my planes as I’d rather just go fly, I don’t care much about the noise reduction and vibration is rarely what destroys my planes its usually gravity lol.
I use braied fish line & really like it so far on the throttle. Very lite, strong & It may even smooth out the vibes that may go to the throtle shaft or servo.
I think just learning at what RPM you engine may viabrate the most ....and then avoiding that RPM range will go a long way to prevent any damage. I like the pull-pull on the rudder too...just seems smother. Best Regards, Capt,n
01-04-2011, 12:33 PM
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RE: Vibration dampning mounts?
ORIGINAL: ptgarcia
Please, nobody get offended, but one of the things that, for some reason, hits a nerve with me is the misuse of the word ''dampen'' or ''dampening'' with reference to shock absorption. The correct words are ''damp'' and ''damping''. We want to absorb the shock...we don't want to get them wet
Please, nobody get offended, but one of the things that, for some reason, hits a nerve with me is the misuse of the word ''dampen'' or ''dampening'' with reference to shock absorption. The correct words are ''damp'' and ''damping''. We want to absorb the shock...we don't want to get them wet
01-05-2011, 12:42 AM
#44
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RE: Vibration dampning mounts?
Beam mounts on glow engines are a hold over from the way models were originally made. We got used to converting beam to radial via an aftermarket part. Radial backplate mounts should have become standard but never did. Standoffs on modern gas engines are the cheapest way to get the job done. They are also the poorest method structurally because of the bending force placed on the case ears. I would like to see a cup mount with cutout holes but standoffs are here to stay just like beam mounts did on glow engines.
01-05-2011, 05:46 AM
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RE: Vibration dampning mounts?
Thanks Kweasel, I have a project (P40) that is set up for beam mounnts but I want to go with a gasser, Are Beam mounted gas engines Okay?
01-05-2011, 12:21 PM
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RE: Vibration dampning mounts?
Well Thanks Cap,n John! Im and Happy and Disappointed to hear that. Happy cause i think iv'e picked out the power plant for my CMP P40 73in. span War-Hawk, The Evolution 40GX, Too Much Engine? Any Suggestions? Dissapointed cause their expensive.
