Hello Good Folks! I'm new to this forum, but not new to BC flying... Thanks for building this community!

I currently have a Helio 391B, an A-1A Husky and an AN-2 for off airport fun, but all are pretty loud. I'm putting a strip in at a property in Vermont and my neighbors are awesome, but they (more specifically their horses) really don't like the sound of airplanes. I just got a line on a new muffler system for the Helio and the Husky has the big prop on it, but I'm wondering if it can be better...

What IS the quietest BC aircraft? What mods are available to quiet these beasts down?

I'm going to the town select/zoning board and want to anchor them on some research or data if possible.

Ideally a 4-6 place, but a 2 placer works if quiet enough.
I'd even consider an experimental if there is a gem out there in the myriad of choices.

Strip: 1200', Grass, clear approach/departure from one end.

Thank you!!!

Slow the prop down will go a long way on making quieter. In the Husky use 25 to 2600RPM, you will have less power but noise will be less.

Kurt

I’ve got an MT Ultra on my Husky, it’s very quiet at 1900 cruising around and pretty quiet even at 2700 on takeoff.

You'll be surprised how quickly the horses get used to airplanes. They adapt very quickly.
On the quiet airplane part, Tom (courierguy) has a Rans S7S that is very quiet. Hopefully he'll chime in here and tell you all about it. He had a long special muffler built for it that really quieted it down.
On the Husky G44 is right, slow the prop down on takeoff and it goes a long way. Makes it much quieter. If your strip is long enough to take off at 2200 RPM or less it really cuts the noise back. Incredible how much quite a plane is spinning at 1700RPM instead of 2200RPM. The big AT802s sound like a microwave taking off compared to the AT402/502. Putting out way more HP but at much less RPM, and that tip speed makes a ton of difference.

Welcome. Like David said, the horses will get used to the noise. Neighbors are fine now, but lawyers are hungry. Don't advertise.

If you can stomach going small, something Rotax 912 powered with the "Swiss" muffler is amazingly quiet. Of course, the prop has to be quiet too.

Years ago I was at Johnson Creek, Idaho hanging out while Courierguy was doing some laps around the patch in his Rans S-7 with the above config. Couldn't hear him.

Here's a good study of real and perceived noise with regards to small airplanes, two-blade vs three.

https://bib.irb.hr/datoteka/593324.AIR-06.pdf

PS I have a friend in Underhill.

Best regards.

At CYNJ we have a couple of Maule's with io-540's. One on wheels and one on amphibs. There take off performance and climb is noticeably better than the similar equipped 185' and they are very quiet. I do not know what they did but between mufflers and prop selection Maule seems to have gotten it right when it comes to lack of noise and excellent performance.

The 915 iS is an extremely quiet engine so any STOL aircraft factory equipped with one will be quiet.

Paired with a Zlin Norden makes an amazing combination! Just listen to the pass at 00:38 seconds here, whisper quiet. https://youtu.be/8AQVwdxS4gw

I’ve seen the Norden in person and that wing is a STOL lovers wet dream.

175 magnum wrote:At CYNJ we have a couple of Maule's with io-540's. One on wheels and one on amphibs. There take off performance and climb is noticeably better than the similar equipped 185' and they are very quiet. I do not know what they did but between mufflers and prop selection Maule seems to have gotten it right when it comes to lack of noise and excellent performance.

The 540 turns slower on takeoff, doesn't it? I suspect that could be a big part of it.

CParker wrote:

175 magnum wrote:At CYNJ we have a couple of Maule's with io-540's. One on wheels and one on amphibs. There take off performance and climb is noticeably better than the similar equipped 185' and they are very quiet.....e.

The 540 turns slower on takeoff, doesn't it? I suspect that could be a big part of it.

One of my flying buddies has an M7-235, it has an IO-540 that redlines at 2400--
same as a local 180 that has the O470U.
Both are noticeably quieter than something like a 185 or my own 470-powered C180 with the 88" Mac.

BTW the Maule M7-260 also has an IO540 but it turns up somewhat higher-- I think 2700.
I suspect that it's gonna be a lot closer decibel-wise to a 180 or 185--
at least it would be if it had the same size prop.

CParker wrote:

175 magnum wrote:At CYNJ we have a couple of Maule's with io-540's. One on wheels and one on amphibs. There take off performance and climb is noticeably better than the similar equipped 185' and they are very quiet. I do not know what they did but between mufflers and prop selection Maule seems to have gotten it right when it comes to lack of noise and excellent performance.

The 540 turns slower on takeoff, doesn't it? I suspect that could be a big part of it.

This. They also generally have shorter props. Tough to get certification for long props on Maules up here in Canada. So you take 2400 RPM with a 78" prop and you have a LOT less noise the 2850 with 88".

Speaking about prop RPM, the 915’s gearbox reduction ratio is 2.54 so with a constant speed prop at the maximum rated 5800 crankshaft RPM, the prop is only turning at 2,280 RPM. With a fixed pitch prop this gets dropped to around 2,000 RPM.

Both Maule's at CYNJ have the 260 hp and their performance seems great and they are quiet. Our Bearhawk with the 300hp Landrover was also quiet with an 84" prop but with 2:1 reduction the prop only turned 2400 on takeoff. It seems good mufflers and slow turning props is the way to go for quiet operations

When my place gets buzzed by another Rotax flier, the noise is less, at least of much shorter duration and overall affect, than the ATV's that buzz down my gravel road. Those big knobby tires on gravel are noisy, I can typically hear them from 1/4 to 1/2 mile away, coming and going.

This Marchetti SM.1019 is electric quiet, no joke. I watched one take off in 250’, a hundred yards from me last week, and you could have a quiet conversation between people ten feet apart while watching it go at full power. You would be shocked how quiet they are, yet are full on wild STOL performers. Admittedly, not budget friendly,

Wow! This forum is awesome. Thank you all. Super helpful.

JohnToo, that paper is really enlightening and not what I expected.

Looks like a large slow turning two blade is the way to go… and duly NOTED on the Husky, plenty of room to pull the prop back on TO (especially since it’s off floats for the winter)… I’m going to try that with the Helio as well with the new muffler kit and see how she performs.

I am also siting the airstrip toward the center of the property to minimize complaints.

Shopping for a Marchetti and looking at 912 powered aircraft… I’m 6’7” so sometimes that is a limiting factor if the seat pads can’t be taken out.

Thank you guys. Hope to see ya’ll in Vermont!