Air Vent Noise

Any DA40 related topics

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chili4way
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Re: New Nose Wheel Fin

Post by chili4way »

AndrewM wrote: Sun Jan 03, 2021 6:26 pm Paul, not sure if you have flown the av gas DA40? If you have, how would you compare the noise from the vents when opened, between the two planes?
I flew a 2004 DA40-180 before my 2019 DA40NG. The DA40NG is quieter overall because of the engine, and I cannot remember specific of the difference in vent-induced noise levels. I think experimenting with tape is probably the best approach if I want to get serious about trying to address this. (I have the air conditioning option.). If there's enough of a difference with/without tape in my airplane, I like the idea of the custom-molded plastic parts over the tape as the long-term solution.
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Steve
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Re: New Nose Wheel Fin

Post by Steve »

chili4way wrote: Sun Jan 03, 2021 4:57 pm I'm confused as to which of the naca vent openings (top or bottom) is the better one to cover/plug to reduce the amount of cockpit noise. The vent plug shown by MarkA plugs the bottom one. The newest version of the DA40NG has only one opening, but it appears to be the bottom one (effectively blocking the top one.
I did a lot of measurements in the past on this very question:

viewtopic.php?f=8&t=4600&hilit=vent+noise&start=40

It looks like someone on the Diamond design team was following our forum, since they copied the solution that we developed...

Steve
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Boatguy
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Re: Air Vent Noise

Post by Boatguy »

Picking up on the molded vent plugs from the fin thread...

I've had my lower vents covered with three layers of glider tape for over a year (one layer fluttered creating some scary noises as reported earlier in this thread). Recently I replaced the glider tape on the left side with a piece of clear plastic cut just slightly larger than the opening and held in place with one layer of glider tape. It's just a little more rigid and durable.

Covering the top vs bottom vent still seems to be a question. This may well be a difference between the cowling on the Lycoming vs Austro. I guess next is to try covering the top vent on the right side and compare the two.
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