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RV-7 cabin noise measurements?

I've used the dB meter on my iPhone to measure it. Around 100 is typical for cruise. Full power is more.

I have an RV6 with carpeted floorboards but few other "soft surfaces" inside.
 
Where are you guys holding the Iphone to measure the sound level? By your ears? I would think the sound levels would vary dramatically where and at what orientation the microphone is facing.

Bevan
 
Interesting...

This thread prompted a bit of research into meter apps for me...

I purchased SPLnFFT Noise Meter for 3.99 for the iPhone.
 
Wonder how these Apps work. I have...well work has a nice high quality Sound pressure level meter. I can take A-weight and C-weighted reading. C is almost always a higher reading, but the A curve is supposed to be what the ear actually is damaged by. I take monthly reading in the power house, this readings coupled with Vibration analysis helps us monitor the gearbox health.

I don't recall the exact numbers, But seem to recall anything over 85dBa has a limited exposure time. Control room is 64-72, other space between 80-105 the peak area is the turbine pit at 104(lowpower)-122dBa(full power).

I'll try to bring it with me one of these days.
 
I'm wondering how much is actually coming from the engine, verses the exhaust, vibration, wind, etc.? From this, how much would a muffler lessen it?
 
Based on the responses, ~100dBA seems. I wonder how that compares to a C172 or C152? Would be nice if it was lower than those two.
 
I think you need to be fair and compare apples with apples. Engine size and noise suppression methods also need to be compared. I used to fly an Arrow with the same engine that I have in my RV 7. I could hear my watch ticking in that airplane. In another one I couldn't hear my self think. They were both equipt the same. That was in the days when no one wore head sets. Huh?, what did you say?
 
hudgin said:
I used to fly an Arrow with the same engine that I have in my RV 7. I could hear my watch ticking in that airplane.
Click to expand...

I'm curious to know what the Arrow has in terms of mechanical and acoustic isolation that might also be feasible to install in the RV-7.
 
spaceflightmeow said:
I'm curious to know what the Arrow has in terms of mechanical and acoustic isolation that might also be feasible to install in the RV-7.
Click to expand...

Whatever it has is far far heavier, more complicated and more expensive than simple noise attenuating (or canceling) headsets. To me it is like wondering how noisy an automobile engine is without a muffler. It doesn't concern me because that is not how I use the device.

Yep, my RV has essentially no noise insulation and I sure like it that way. If my headset disintegrates in flight someday then it will be uncomfortable for me for a few minutes.
 
RV-6A, meter at about top of stick position. No sound insulation to speak of except foam pad and carpet in the footwells. A weighted measurements by rpm and also the Z weighted levels and overall spectrum.
As you can see, most of the energy is at the prop frequencies. That is why the un-weighted Z measurement is so much higher.

Measured with an NTi XL2 meter: http://www.nti-audio.com/en/products/xl2-sound-level-meter.aspx

audiolevels.jpg
 
Last edited:
I tried to reply to your question but got timed out. I'll get back later. I had to log back in just to write this so I going to bed.
 
Holy cow, FL-mike, you win the thread. Excellent data. What is the significance of most of the energy being at the prop frequency? My guess is that it prop noise would be acoustic noise, penetrating through the drum-head firewall and also beating down on the canopy.
 
hudgin said:
I tried to reply to your question but got timed out. I'll get back later. I had to log back in just to write this so I going to bed.
Click to expand...

That's MADDENING isn't it! I've found that hitting the Preview Post button occasionally will keep you logged in.
 
spaceflightmeow said:
Holy cow, FL-mike, you win the thread. Excellent data. What is the significance of most of the energy being at the prop frequency? My guess is that it prop noise would be acoustic noise, penetrating through the drum-head firewall and also beating down on the canopy.
Click to expand...

The blade pulses on the windscreen and exhaust pulses on the floorboards?
I think each cylinder fires every 180 degrees, so that is the same as a two blade prop blade frequency. 2*2700/60
 
muffled exhaust

Just put my order in for a muffled exhaust from vetterman, larry said it will reduce noise by approx 6db wbat else was interesting was when they dyno the new 1.5 vs 1.75" crossover system the 1.5 came out in front in hp accross the range? Huh...anyway i'll give it a go.

I like the data just makes arguments so much simpler....
 
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