IMAC Noise Rule (Newbie)
02-19-2007, 02:14 PM
#1
IMAC Noise Rule (Newbie)
I'm planning on competing in IMAC this year in NC. I'll be flying Basic to start with, but may make the move to Sportsman mid-season...
How are the CDs -really- going to apply the noise rules? Not that I disagree with it, but I just ordered every thing needed to finish my plane. Probably should have asked this before I ordered it...
Setup:
H9 CAP 232G
DA 50
J&A Pitts Style Muffler (wraparound)
Menz 22 x 8 (wood)
TT Spinner (don't think this matters)
Estimated weight is 15.5lbs. I did weigh everything I have and found weghts to estimate for what I don't. I really don't want to add weight if I don't have to.
If I need a quieter set up, it would be best to know now so I can fix it before the order ships. I have no idea about where this set up will be on noise. 1st IMAC plane and 1st gasser...
Thanks for your help...
Larry
How are the CDs -really- going to apply the noise rules? Not that I disagree with it, but I just ordered every thing needed to finish my plane. Probably should have asked this before I ordered it...
Setup:
H9 CAP 232G
DA 50
J&A Pitts Style Muffler (wraparound)
Menz 22 x 8 (wood)
TT Spinner (don't think this matters)
Estimated weight is 15.5lbs. I did weigh everything I have and found weghts to estimate for what I don't. I really don't want to add weight if I don't have to.
If I need a quieter set up, it would be best to know now so I can fix it before the order ships. I have no idea about where this set up will be on noise. 1st IMAC plane and 1st gasser...
Thanks for your help...
Larry
02-19-2007, 02:24 PM
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RE: IMAC Noise Rule (Newbie)
i did a brison 3.2 about 2-3 year ago in the basic with the 22 x 8 menz and a j & h peacekeeper and i made the mark mark with flying colors on noise with about 5 dp or so to spare. i am not sure have the noise req. changed since then.
02-19-2007, 03:53 PM
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RE: IMAC Noise Rule (Newbie)
That set up will be OK.
THE peace keeper mufflers are good.
You really don't have to worry about the CD's as a first step.
The judges will let you know if you are too noisy.
When you are flying the judge will grade your noise level.
If you are too noisy, they will make they initial call.
With that said, I really haven't seen a plane with a muffler and good throttle management fail the noise level.
Exhaust deflectors and/or poor throttle management can get you into trouble
THE peace keeper mufflers are good.
You really don't have to worry about the CD's as a first step.
The judges will let you know if you are too noisy.
When you are flying the judge will grade your noise level.
If you are too noisy, they will make they initial call.
With that said, I really haven't seen a plane with a muffler and good throttle management fail the noise level.
Exhaust deflectors and/or poor throttle management can get you into trouble
02-21-2007, 08:21 AM
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RE: IMAC Noise Rule (Newbie)
we used a dB meter at several of our contests.......
I don't think anyone even came close to failing based on IMAC rules.....
One thing I found interesting is this.... many local fields have rules that say "no gas airplanes" and usually it is a noise concern.
However, at any contest that we had the dB meter, the loudest planes were glow planes......
Have fun with IMAC!
plan on going to the judging seminar in Muncie in April.... it is a really great weekend to learn about IMAC and really informative
I don't think anyone even came close to failing based on IMAC rules.....
One thing I found interesting is this.... many local fields have rules that say "no gas airplanes" and usually it is a noise concern.
However, at any contest that we had the dB meter, the loudest planes were glow planes......
Have fun with IMAC!
plan on going to the judging seminar in Muncie in April.... it is a really great weekend to learn about IMAC and really informative
02-22-2007, 10:14 AM
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RE: IMAC Noise Rule (Newbie)
Larry - come early to Muncie. You can fly Friday afternoon/evening, Saturday evening, and most of Sunday afternoon. There will likely be lots of experienced pilots there on Friday afternoon to help you. Don't be afraid to introduce yourself as new and ask for help. You will get plenty and it would be a great way to get started on the right foot. I'm hoping to be there, but it all depends on work/travel schedules.
Ken
Ken
03-03-2007, 05:37 PM
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RE: IMAC Noise Rule (Newbie)
What are the noise rules exactly? I want to try my hand at a couple IMAC contests this season, in Basic class with a 67" Edge 540 that will have a SuperTigre 90 and a Pitts muffler. I agree that 2C glow enginers are the loudest and most annoying sounding of all engines. However, they are the cheapest, and for me a smaller glow plane is the only way I can afford to jump into the IMAC scene.
I've only run this engine (it's my first 2-stroke) on a test-stand with the stock muffler but it is LOUD. Thing is, I don't have access to a dB meter, so I have no idea really how the "loudness" I am hearing translates to the IMAC rules limitations. This is on a concrete surface, in a fenced in backyard, but still....I'm going to have to take it to the field to break it in, or my neighbors will kill me. I am putting a Slimline large-volume Pitts muffler on it in the airplane, not sure if this will improve the sound or not.
Do you IMAC guys check your sound levels with a dB meter? Where do you get/borrow one of those? Or can you just tell that if is not obscenely LOUD then it will pass the IMAC sound check? I guess I just assume that the stock muffler on 2C glow engine would be enough to pass a sound check, but it sounds like it is up to the judges to initiate any kind of an official check of the model's noise level. This has got me thinking that with my "little" ST G90 my plane will sound louder than any of the larger aircraft.
I've only run this engine (it's my first 2-stroke) on a test-stand with the stock muffler but it is LOUD. Thing is, I don't have access to a dB meter, so I have no idea really how the "loudness" I am hearing translates to the IMAC rules limitations. This is on a concrete surface, in a fenced in backyard, but still....I'm going to have to take it to the field to break it in, or my neighbors will kill me. I am putting a Slimline large-volume Pitts muffler on it in the airplane, not sure if this will improve the sound or not.
Do you IMAC guys check your sound levels with a dB meter? Where do you get/borrow one of those? Or can you just tell that if is not obscenely LOUD then it will pass the IMAC sound check? I guess I just assume that the stock muffler on 2C glow engine would be enough to pass a sound check, but it sounds like it is up to the judges to initiate any kind of an official check of the model's noise level. This has got me thinking that with my "little" ST G90 my plane will sound louder than any of the larger aircraft.
03-03-2007, 06:03 PM
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RE: IMAC Noise Rule (Newbie)
Larry!! Sory I missed your post.. I get there mid morning on Friday and we fly until it gets dark!!
I haven't decided if I am camping there or getting a hotel....
as for sound
From the Rule book:
found here
http://www.modelaircraft.org/comp/07...aerobatics.pdf
I haven't decided if I am camping there or getting a hotel....
as for sound
From the Rule book:
found here
http://www.modelaircraft.org/comp/07...aerobatics.pdf
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
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
