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FG Sound Project
Hi Everyone!
I would like to start a sound analysis project here on FG. The basis behind the FG Sound Project is to assess the best ways in order to accomplish noise control with giant scale model planes. I recently posted on FG regarding what would be my best muffler options for a DA 150 I purchased. The reasoning behind this is that I might be moving in the next 18 months and sound might be an issue for both IMAC and 3D flying just using standard mufflers. There have been claims that using the left thumb (I.E. throttle control) is the best method for controlling sound whereas others believe that canister mufflers are the best at quieting down engines. Then, there is the idea that tuned pipes are the best route because they will both quiet the motor down and add power. With all these options, newbie’s such as myself can go nuts trying to figure out the best combination and even become frustrated with the different options. Therefore, the goal of this project is to collect and statistically analyze to determine true differences in sound levels and hopefully performance levels too. Furthermore, once I know what affects what, I can derive equations to predict performance and sound. Please be aware that this would only be a prediction and not 100% accurate. I would like to say that this is not to settle any sound nor set up debates but to provide information to the RC community whether you’re a Sunday flyer or a serious IMAC/Freestyle competitor. This is also not to state that a particular set up is superior or inferior in any way. It is my hope that if someone has a particular set up that they like but might need to quiet down their flying, that this would help them to decide the best changes to make. In order to do this, I will need the following information. Also, partial information is OK but please try to make things as accurate as possible: True sound readings in decibels Static thrust measured by a scale Your set up information (I.E. motor, cans, standard mufflers, pipes, prop size and blade number, prop material) Altitude of where the measurements were taken You can email this information to FGSoundProject@gmail.com I will also entertain any questions regarding this project and I will do my best to explain the various aspects of what I’m doing. Please feel free to post questions in this thread because I would like it to be open. Thanks, ben_beyer |
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Re: FG Sound Project
Ben,
I think it is a great idea what you are looking to do but being a muffler manufacturer we deal with questions like this everyday and one of the biggest things is the standardization of db measurements. The extranious varibles that we see everyday when people are testing the db level of there engine is unbelievable. I think if you want to get a more accurate scale of this you need to specify how you want people to check the db. Things I would look at: are there any structures around which will reflect the noise Grass or hard surface Measurement from the left, right, or front height of the db meter scale the db meter is set to distance of measurement even brand of db meter you may want to make an excel file or something that guys can print out and fill out when they are doing it. that just a couple of thoughts I had. Kevin |
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Re: FG Sound Project
Ben,
It's also been found, through IMAC's sound ground testing, that the decibel level on the ground has no direct reflection on the noise you will make once airborne. A DA150 with tuned pipes and a three blade prop can be a very loud setup if the left stick is not utilized properly. Also, if you can get ahold of some of the past documented data, a DA150 on standard mufflers with a Mejlik 32-10 will ground test at a lower db than most canister/pipe three blade setups. |
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Re: FG Sound Project
Poll: NAT's and Sound ( 1 2 3 4 5 6 7 8 9 10 ... Last Page)
McFueler I have found more info on the above thread here on FG than anywhere else. Ben - your goal is admirable and I wish you luck in collection of accurate data as it is very difficult to find. My club is noise sensitive and I fly the largest planes at my field. I am always a target for the Sound Nazi's. I have found that the left stick is the largest contolling factor in the air but on the ground testing can be a challenge. It can be quite costly experimenting on your own to find something that will pass. I had good fortune recently in putting a Mej 31X12 Evo Light on my 3W 157 L90 canister set up. I was running a Xoar 32X10 Eagle nose and in the air it would unload in any position other than completely verticle and the exhaust racket, not prop, was deafening. My 1st attempt was the 31X12 Evo Light and at $148 plus shipping it would have been more wasted dollars down the drain looking for a combo that might work if it had not. It did though - pulled hard through any manuver and was very quiet. Unfortunately there is little concrete data to guide you. Hope your efforts work and I certainly will subscribe, follow and contribute if I can. |
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Re: FG Sound Project
I could not attach an excel file so what I need is the information I requested earlier. Yes, height of the db meter, brand, and all that may have an effect, but in statistics you need to focus on the points that will most likely have the largest effect. Furthermore, the point of this is to apply to sound differences overall. As such variation due to db brand meter, height of the measurement, surface and all that will figure into the error.
Catalog and ad companies literally have thousands of different combinations and they do try to use statistics to find the most effective methods. However, making all those different combinations can't be done so they take into account which ones they think are the most effective and make gradual changes from there to increase success. Once again, I appreciate the comments and I did take them into account, but the question I am trying to answer is applicable to all db meters, surfaces, etc. |
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Re: FG Sound Project
In a club near to me, the flying field rules are as follows for noise:
1) Noise suppresion is 90DB maximum 2) Clubs DB METER only to be used. 3) The meter needs to be placed on a stand 12" of the ground. 4) The meter will be placed downwind from the exhaust side of aircraft. 5) The meter needs to be placed 20' from the exhaust end of aircraft. Is this more or less a standard noise test procedure? |
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United States, FL, Palm Bay
Joined Mar 2008
1,331 Posts
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Re: FG Sound Project
Visit the Mini-iac website and you can find where there have been numerous contributions(being politically correct) to the onerous task of fact finding missions of sound control.The Red book of IMAC has a standard that was used and gives a guideline of how it was tested in the past. As DA2000 stated this is a relative to the left thumb when it comes to the final criteria..We just had the SE Regionals in Jacksonville and you can see the scores that were given on 40 plus pilots and the variances given from flight to flight..also one must consider all the enviromental effects when judging and ascertaining the facts that you collect....So..soo ..soo many variables that need to be include d...especially if you are brave enough to post your findings here on FG...you will quickly find that everyone who thinks they know will challenge your findings on every variable you use as a control factor..ie...from what is sound to pitch of prop to how tall are you to weight of glue in the plane..JMO. Your effort will be both commended and condemnd. In the final analysis of it all you will more than likely find the chief controlling factor lies in two areas....1 $$$$$$$$$...2...where and who you are flying with....3D pilots love the noise/sound and the more Senior flyers look upon it in a more negative fashion unless they are flying WARBIRDS cause they are supposed to be loud...best of luck...pops
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Re: FG Sound Project
Yes, BUT by factoring in all variables you may be committing serious errors in your conclusions. The error term will be so low that even the smallest factor will be highly significant whereas you're trying to identify the true sources of variation. So, as stated before, I took everyone's comments into consideration, but for now I am A) trying to make this applicable to all db meters, situations, and a standard db test given by pryor808 and B) identify the factors that have the biggest effect on db levels.
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United States, FL, Palm Bay
Joined Mar 2008
1,331 Posts
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Re: FG Sound Project
COOL...results should be interesting...good luck
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