The Gas Engine Decibel Thread
03-04-2006, 04:12 AM
#26
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RE: The Gas Engine Decibel Thread
I'm from Texas and making noise is an important part of the local culture. There are no diesel pickups more than a week old that still have mufflers, this goes for all the Harleys also, and dirtbikes, jetskis, pretty much anything with an engine. A pattern plane will keep the attention of an audience for about ten seconds, just doesn't excite the scences I quess.
03-04-2006, 11:04 PM
#27
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RE: The Gas Engine Decibel Thread
Got a reading today on my 28% Cap:
Fuji 50EI
Stock muffler
Mejzlik 22x8
7150 RPM
Asphalt
91Db (3 meters)
I would have never bought this motor, I won it at a funfly, I must say at only 6 ounces more than the DA-50 RTF and over $150 less it rocks pretty well!
Fuji 50EI
Stock muffler
Mejzlik 22x8
7150 RPM
Asphalt
91Db (3 meters)
I would have never bought this motor, I won it at a funfly, I must say at only 6 ounces more than the DA-50 RTF and over $150 less it rocks pretty well!
03-16-2006, 10:52 PM
#30
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RE: The Gas Engine Decibel Thread
FWIW, TS 52 3.2 stock Pitts style
concrete surface 22x8 menz 7420rpm 92db
" " " 23x10 sq, tip zinger (chopped 24) 6000rpm 88db.
18lb plane 80" wing.
concrete surface 22x8 menz 7420rpm 92db
" " " 23x10 sq, tip zinger (chopped 24) 6000rpm 88db.
18lb plane 80" wing.
03-18-2006, 10:25 AM
#32
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RE: The Gas Engine Decibel Thread
I have recently changed my DA 100 from standard mufflers to a set of KS 1060 tuned pipes.
We dont really get the sound meter out here but I can tell you that ground noise has absolutley no bearing on in flight noise.
Lets say you are propped right, if you do a ground run, especially if the breeze isnt into the nose of the model you will get a hell of a lot of cavitating noise. This cavitation is not present in the air as the model is moving.
When I first fired the DA up after the pipes were installed I was a little dissapointed as there was no apparent recuction in noise whilst on the ground. However once the model is rolling and then at flying speed it is a completely different story.
The noise is reduced by a remarkable amount. I fly a 28-10 Mejlik prop and it will only rip if you do stupidly fast high throttle passes out of a dive. (It a 2.6 yak so I dont do that).
What I am trying to point out is that a correctly propped large petrol motor will make a lot more noise on the ground than in the air. That loud ground noise is caused by cavitation, not muffler noise, that caviataion is only apparent whille the model is static.
In small glow type models the majority of noise is exhaust note and testing them for dB while static is a fair solution as exhaust is just as noisy moving or not moving.
But a ground static dB reading on a large petrol model is meanignless, especially on a tuned pipe equipped model like mine. In the air there is no exhaust noise apparent at all, just a prop hum, its still a noisy bugger on the ground though.
We dont really get the sound meter out here but I can tell you that ground noise has absolutley no bearing on in flight noise.
Lets say you are propped right, if you do a ground run, especially if the breeze isnt into the nose of the model you will get a hell of a lot of cavitating noise. This cavitation is not present in the air as the model is moving.
When I first fired the DA up after the pipes were installed I was a little dissapointed as there was no apparent recuction in noise whilst on the ground. However once the model is rolling and then at flying speed it is a completely different story.
The noise is reduced by a remarkable amount. I fly a 28-10 Mejlik prop and it will only rip if you do stupidly fast high throttle passes out of a dive. (It a 2.6 yak so I dont do that).
What I am trying to point out is that a correctly propped large petrol motor will make a lot more noise on the ground than in the air. That loud ground noise is caused by cavitation, not muffler noise, that caviataion is only apparent whille the model is static.
In small glow type models the majority of noise is exhaust note and testing them for dB while static is a fair solution as exhaust is just as noisy moving or not moving.
But a ground static dB reading on a large petrol model is meanignless, especially on a tuned pipe equipped model like mine. In the air there is no exhaust noise apparent at all, just a prop hum, its still a noisy bugger on the ground though.
03-18-2006, 10:36 AM
#33
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RE: The Gas Engine Decibel Thread
Just as an addition, when I fly with glow models in the air I find I actually really strugele to hear my model over them. Even 4 stokes. It has given me a few heart stopping moments when I have though my motor had actually stopped
06-06-2006, 07:23 PM
#34
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RE: The Gas Engine Decibel Thread
where do you live i live on lake whitehall want to know rc truck shops around here email at [email protected]
