This year the SA Nats are being told we must do a ground sound test. I want to see if this is going to hurt attendance, so please vote.What I'm talking about when I say cheat switch is having your throttle set up so that when you flip a switch you plane will not go to full power.


1. Yes I'm attending the 2010 SA Nat's even if we have ground sound testing.I believe I can pass it without a cheat switch.

2. No I'm not attending because of the ground sound testing, don't believe I can pass it without a cheat switch even though i'm very quiet in the air.

3.Yes I'll be attending and I'll be using a cheat switch.

4. Don't care one way or the other because I never attend the Nat's anyway.

Mark are you going to put the same poll on the IMAC site..pops

I put a link over there that brings you here to vote.

What DB limit are they trying to get under?

from the rule book

Scale Aerobatic Sound Limits:
5.1: Maximum Sound Levels. The maximum ground sound level for all classes shall be: 96dBA measured on soft surfaces and 98dBA measured on hard surfaces. Contest Directors may implement a correction factor due to unusual conditions.
5.2: Standard Method of Sound Measurement. The sound measurement shall be taken with the sound meter set to the ―A‖ weighting, slow response with windscreen installed. The sound meter shall be placed downwind, twenty-five feet from the model centerline and positioned in line with the prop arc at twenty-four inches in height (see Fig. 1). The sound meter shall be pointed directly at the model and perpendicular to the fuselage. The model being measured shall have its engine run at full power for the sound test. No noise reflecting objects will be allowed within three feet of the sound meter.
5.3: Ground Sound Level Test. Prior to flying the first round of a contest; each competition model must pass the Ground Sound Level Test. The Ground Sound Level Test must be completed at the sanctioned contest site by the Contest Director or his/her designee. Testing shall be done in an area
designated by the Contest Director and may be completed prior to or during the first round. Models
successfully completing the test will not be measured again during the contest unless their sound level is
deemed to have increased significantly since the initial check by the Contest Director. Any plane that fails
the test will not fly, but will be moved to the back of the flight order, and allowed one more attempt to pass
the test. Any model that fails the second test will zero all judged sequences he would have flown during
the current round. Any model that fails the second test may be tested again during future rounds with the
same Ground Level Sound Test criteria being applied. No model will fly any judged sequences at any Scale
Aerobatics contest until it passes the Ground Sound Level Test.

Originally Posted by exeter_acres

from the rule book

Scale Aerobatic Sound Limits:
5.1: Maximum Sound Levels. The maximum ground sound level for all classes shall be: 96dBA measured on soft surfaces and 98dBA measured on hard surfaces. Contest Directors may implement a correction factor due to unusual conditions.
5.2: Standard Method of Sound Measurement. The sound measurement shall be taken with the sound meter set to the ―A‖ weighting, slow response with windscreen installed. The sound meter shall be placed downwind, twenty-five feet from the model centerline and positioned in line with the prop arc at twenty-four inches in height (see Fig. 1). The sound meter shall be pointed directly at the model and perpendicular to the fuselage. The model being measured shall have its engine run at full power for the sound test. No noise reflecting objects will be allowed within three feet of the sound meter.
5.3: Ground Sound Level Test. Prior to flying the first round of a contest; each competition model must pass the Ground Sound Level Test. The Ground Sound Level Test must be completed at the sanctioned contest site by the Contest Director or his/her designee. Testing shall be done in an area
designated by the Contest Director and may be completed prior to or during the first round. Models
successfully completing the test will not be measured again during the contest unless their sound level is
deemed to have increased significantly since the initial check by the Contest Director. Any plane that fails
the test will not fly, but will be moved to the back of the flight order, and allowed one more attempt to pass
the test. Any model that fails the second test will zero all judged sequences he would have flown during
the current round. Any model that fails the second test may be tested again during future rounds with the
same Ground Level Sound Test criteria being applied. No model will fly any judged sequences at any Scale
Aerobatics contest until it passes the Ground Sound Level Test.

Thats what i was afraid of..... I have a 170 on pipes with a 30x13, there is no way that thing will pass on the ground.

As a pattern guy that will be flying IMAC this year, I don't see what the big deal is with sound, as that's what I've (I guess this is the best way to put it) grown up with. That being said, I've attended two IMAC contests as a spectator/chair weight, so I'm relatively green when it comes to rules and why things are the way they are. I suppose after I attend a few more contests as a participant, partake in a few conversations aided by barley sodas, and irreparably damage my heart by hanging out at Camp Cholesterol, then I will understand. I also am too poor to buy a DA200 so I have that going against me as well, though with a 3-blade on an AW Ultimate, it is very quiet.

So far from what I see of the attending Pilots everyone will get a plaque.

Mark C, I asked the question over on the IMAC site as to what peoples thoughts were if the setup Brendan is running would pass. I had already talked to someone else and they said no, and I believed them, I only posted what I did to bring it to light so to speak, it was very evident in the replies from others that they also know it wont pass. There isnt anything from what I seen that could be done to a DA 170 with prop and exhaust combinations that would pass the sound test.

Someone posted in using sound test equipment that they bought themselves and did testing said, that the limits they were at were right on the margin of passing or not BUT, due to weather, temps, humidity and all that, they could go to Muncie and then not pass.

Rick posted the db test they did from a contest last year, from looking at that, there is no way I am going to send in entry money to AMA that is non refundable, drive to Muncie and be out the expense of fuel to fail the test and there be nothing I can do to fix it and have to turn around and drive back home, that would be sensless and stupid on my part to even think about it.

As to the cheat switch that some have mentioned using to limit the throttle travel....if the engine isnt run at full throttle, and we all know what full throttle is...its cheating to use such a thing, who wants to cheat in order to be able to compete ?

In the sound testing, I beleive that there are enough of the guys around that know what the engine RPM's are supposed to be....during the sound check I believe that the engine RPM's should be checked during the sound check to make sure that the RPM's arent several hundred below what they are supposed to be, you see a big drop in RPM's then you know the engine isnt running at full throttle, if they arent then the sound check isnt a true honest check and the rules are not being applied and the sound test is then subjective and not true.

So during the sound test, are RPM's going to also be monitored so no cheating is allowed ?

Over proping a plane may be another way to get around it, but then again, you would need to change props in order to fly, after the sound testing is done, are equipment changes going to be allowed and, if you make an equipment change, sound testing should be applied again because that is not what you tested with to begin with.

Dan O,
I couldn't agree more. They might as well just cancel the whole event if there going to do the ground sound testing. Back when they started testing I couldn't pass it then without a trick and sure couldn't pass it now.

Hey Dan ! My point on this is, if they are going to do the sound testing then other measures need to be made to make sure that there is no cheating allowed in order to beat the sound test so, RPM's would need to be checked, whatever you use to do the sound test with, that is what you have to use to fly and no one being allowed to go and change props or whatever after the test is done, if you change something after the test, you have to retest

When the test is preformed, take notes just as Rick did during his test, engine brand, size, exhaust used, prop brand and size....if during the contest someone has changed a prop and you get caught, your disqualified unless you go through the testing again..

Mark C, would it be ok to post the test sheet that Rick did on here ?

Ask yourselves how many other events and other disciplines will be at the AMA site this summer.
Then ask around and see how many of those will be enforcing sound parameters..

Heres a clue.. None.

Well if they want to enforce sound rules at Muncie then it should apply to all and not just one, even though we know that isnt going to happen

You sure about that, Wayne?

I know pattern does, and helis have a provision for sound checks in their rules.