Air intake vent tape

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Rich
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Re: Air intake vent tape

Post by Rich »

I took some measurements today, as it looked like the vent locations are not the same between right and left side. I was right. The left side vent is about 2 cm higher and about 1 cm further aft than the right.

The previous flights I hadn't thought to check the effect on the right side vent with respect to noise. I checked both on Saturday. It seems the tape I applied on the right is not quite as effective in flight as the left. Still an improvement, though.
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Re: Air intake vent tape

Post by greg »

For quite a few years, I would gloat internally that I had one of the few DA40s that didn’t have noisy vents. I didn’t understand what you were all complaining about. Then it all changed a couple of years ago - I changed from passive to active noise reduction headsets. Now I get the vent noise, and amazingly (since It must have been there all the time previously) the noise now really annoys me!

So, there is a alternative solution to tape and plugs - buy my old PNR headsets :D
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Re: Air intake vent tape

Post by Steve »

I was going to use some expanding polyurethane insulating foam to fill the upper vent cavity, but...

I did some experiments, and the foam didn't really fill very well, and I didn't want to deal with the mess. The instructions on the spray can also noted that the cured foam may be flammable. I figured that it wouldn't be a great idea to have a chunk of possibly flammable foam in a cabin air intake next to the engine compartment...

So, I just peeled the old tape off (it lasted 7 or 8 years):
Right side NACA vent, old tape
Right side NACA vent, old tape
Left side NACA vent, old tape
Left side NACA vent, old tape

Cleaned off the old adhesive, and reapplied one strip of clear duct tape for reinforcement under a single piece of white glider tape. It looks good to me...

Right side, new tape
Right side, new tape
Left side, new tape
Left side, new tape

Good for another 8 years!
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jwx96
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Re: Air intake vent tape

Post by jwx96 »

I don’t tape my vents on the outside. I think I’ve gotten used to the noise and it really doesn’t bother me. I do cup the mic with my hand when talking to ATC though. (I use the original Lightspeed Zulu headset.) In the winter I tape the front vents on the inside to help keep the cabin warmer, but run a string under the tape so that I can rip the tape off quickly if there is a CO issue.
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Re: Air intake vent tape

Post by dant »

I think I’ve gotten used to the noise and it really doesn’t bother me.
I thought so too until I tried it. It's really dramatic.
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Re: Air intake vent tape

Post by Rich »

A couple of days ago I had occasion to test effectiveness under full-RPM conditions. I found it not nearly as effective with the propwash at maximum. Still fine at 2400 RPM cruise, where the majority of my flight time is spent.
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Re: Air intake vent tape

Post by Boatguy »

The Austro engine is a little quieter than the Lycoming. Taping the vents makes a dramatic difference in the NG. Closing them entirely is even better and one of the nice things about flying in Winter!
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Re: Air intake vent tape

Post by dant »

The Austro engine is a little quieter than the Lycoming
A year or two ago I was sitting in south parking at KBFI preflighting a Galvin Da40 when another nearby privately owned NG started up. Not that I would have known. It was more of a "look back at the plane, oh wow the engine is running now, holy shit that was quiet".
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Chris B
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Re: Air intake vent tape

Post by Chris B »

Steve wrote: Sat Oct 01, 2022 7:55 pm I was going to use some expanding polyurethane insulating foam to fill the upper vent cavity, but...

I did some experiments, and the foam didn't really fill very well, and I didn't want to deal with the mess. The instructions on the spray can also noted that the cured foam may be flammable. I figured that it wouldn't be a great idea to have a chunk of possibly flammable foam in a cabin air intake next to the engine compartment...
Did you consider using the Divinycell foam per Tom's post?

Apparently that shapes easily, is unfazed by fuel, and flame resistant. ¯\_(ツ)_/¯
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Steve
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Re: Air intake vent tape

Post by Steve »

Chris B wrote: Sat Oct 08, 2022 4:51 pm
Steve wrote: Sat Oct 01, 2022 7:55 pm I was going to use some expanding polyurethane insulating foam to fill the upper vent cavity, but...

I did some experiments, and the foam didn't really fill very well, and I didn't want to deal with the mess. The instructions on the spray can also noted that the cured foam may be flammable. I figured that it wouldn't be a great idea to have a chunk of possibly flammable foam in a cabin air intake next to the engine compartment...
Did you consider using the Divinycell foam per Tom's post?

Apparently that shapes easily, is unfazed by fuel, and flame resistant. ¯\_(ツ)_/¯
No, but years ago I tried a similar type of fireproof foam. It required taping it in anyway with the glider tape to look halfway decent, and it didn't give any SPL reduction advantage over the tape alone.
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