Noise and Noise Footprint IO-550 vs IO 470?

[morrisond]

Hi,

I've been following this forum for a while and considering building an 260se. I will be going to AOPA to see them in person.

The two Airports I operate out of are generally Noise sensitive. Toronto City Centre and our own Strip (CNW2) on Lake Rosseau in Muskoka for those that know the area.

I'm also sensitive to the impact that general aviation has on noise levels.

Will the IO-550 with a three blade prop, have a smaller noise footprint and lower overall noise levels(not to mention better performance which is a nice plus) than the IO-470 with the 2 Blade? What about inside the Cockpit?

Thanks

[kwmoore]

Welcome to the forums! I'll look forward to meeting you at AOPA.

While I don't have the exact numbers, I can tell you my own qualitative observations that the IO-470 (max rpm 2625) is as expected noticeably louder than the 182's stock O-470 (max rpm 2400). However you can reduce rpm after takeoff to 2450-2500 to reduce noise with only a minor performance penalty.

Regarding the IO-550, it produces 300-310 hp at about 2700 rpm. If the prop is shorter than the usual 2-blade on the 260se, tip speeds and noise may be lower, even with the higher rpm (2700 vs. 2625). Here my own subjective experience with an IO-550/3-blade plane (SR22) suggests that this combination is as loud as or perhaps louder than a 260se on the takeoff roll. However note that the 260se's run is much shorter and climb gradient is greater than the SR22, so that by the time you cross the airport boundary you should be higher (and thus quieter as perceived on the ground).

The 260se is MUCH quieter than planes like the C185 which produces an unbelievable racket at full rpm.

Perhaps Todd or one of the more technically-inclined folks here has the precise db numbers? :o

[nworth]

I am back to 2500 at 500 ft from my home airport at Sarasota. That's usually on the long (9000 ft) runway so I am at reduced RPM well before the crossing runway and at about 900 ft by the airport property. I'm sure all those factors contribute to a noise reduction.

My airplane will be shown by Todd and Jo at the show and I will be there Fri-Sun if you would like to get an owner's view of the plane.

[morrisond]

Norm,

I look forward to seeing your plane. I've read your saga on building it. Will you ever finish the story? Do you have the chute installed yet? Pictures? I'll be there on Friday.

[nworth]

Norm,

I look forward to seeing your plane. I've read your saga on building it. Will you ever finish the story? Do you have the chute installed yet? Pictures? I'll be there on Friday.
I plan on finishing the story once the plane is finished! Right now, it's still being painted... It's looking increasingly unlikely that the parachute will be installed before AOPA. Also, I had some problems with some of the electronics (vendors) and wanted to see how these issues were resolved before setting off any false alarms.

I figure the AOPA show will form a good bookend for the saga so you can expect to see the final installment mid-November.