Are there quiet cabin GA planes?

[Neal Howard]

My old Cherokee 140 had enough insulation in it that you could actually hold a conversation with someone in the right seat without headphones on, but was still loud enough that sustained exposure surely would lead to hearing damage eventually. It was quieter than the C172 I trained in. The RV is definitely a different story... without Zulus, it's like riding inside a jackhammer.

 

[Ted]

Your point about the props is well taken. The Encore had a two-blade paddle prop while the Acclaim has a three-blade scimitar prop. They're both turbos, though.

Ahh, didn't realize the earlier one was turbo.

I'd really like quieter props...

And turbos... or superchargers.

 

[SixPapaCharlie]

Whats the diff. between turbo and supercharger?

 

[Ted]

Turbos are exhaust driven (hence the muffling effect on exhaust noise), superchargers are crankshaft/belt driven.

Both have their advantages.

 

[MAKG1]

Turbos are exhaust driven (hence the muffling effect on exhaust noise), superchargers are crankshaft/belt driven.

Both have their advantages.

Specifically, turbochargers can be designed to run off waste energy and not rob the crankshaft (at a specific RPM), but can take some time to spin up. Superchargers don't lag due to a direct connection to the crankshaft, but always rob the crank of energy you could be using to spin the prop.

 

[Henning]

Whats the diff. between turbo and supercharger?

A turbo charger is a supercharger, hence the TSIO nomenclature on Continentals (Turbo Supercharged Injected Opposed). The Turbo Supercharger, shortened to turbocharger, uses a turbine wheel in the exhaust stream to drive the compressor section on the opposite side of the same shaft. Straight up superchargers are mechanically driven by the crankshaft rotation be it through a belt or gears.

A supercharger is any device that pressurized the charge air above ambient. A turbocharger is a supercharger driven off exhaust waste energy for the most part. A simple supercharger uses prime production energy as a drive.

The 20-645-E7 EMD engines used a hybrid. There was a full turbocharger set up (over 3' in diameter) that had a stub drive to the center shaft with a sprag clutch to a gear drive. These are 2 stroke Diesels so they need a supercharger to run. With this set up at low speed the crankshaft is driving the supercharger, and as the exhaust flow takes over the turbine over runs the sprag clutch and runs the supercharger.

 

[Henning]

Specifically, turbochargers can be designed to run off waste energy and not rob the crankshaft (at a specific RPM), but can take some time to spin up. Superchargers don't lag due to a direct connection to the crankshaft, but always rob the crank of energy you could be using to spin the prop.

Mostly waste energy, they cost about 2"MP of power, still a really good deal.

 

[Ted]

Specifically, turbochargers can be designed to run off waste energy and not rob the crankshaft (at a specific RPM), but can take some time to spin up. Superchargers don't lag due to a direct connection to the crankshaft, but always rob the crank of energy you could be using to spin the prop.

Correct. But since airplanes are steady state devices, the energy robbing isn't a big deal since it's always occurring. A properly sized supercharger won't have pump losses when run at an ideal altitude since you'll be at WOT. A turbo will rarely have that, but will always have exhaust backpressure, and turbos tend to heat the induction air more unless an intercooler is used.

The failure modes associated with turbos in aviation engines are making me think superchargers have a lot of advantages. Like I said, both have their advantages depending on the specified operation of the aircraft.

 

[docmirror]

The failure modes associated with turbos in aviation engines are making me think superchargers have a lot of advantages. Like I said, both have their advantages depending on the specified operation of the aircraft.

Most aircraft superchargers are not roots type but are centrifugal which have similar failure modes on the turbine side, and different, but still serious failure modes on the drive side. There's no free lunch.

I built a VW buggie with a Paxton SC on it which was a blast, but blew one of the jugs off after a season. It was designed for a 300CI engine, and I had it on a 2200cc engine -- oops.

 

[Ted]

Most aircraft superchargers are not roots type but are centrifugal which have similar failure modes on the turbine side, and different, but still serious failure modes on the drive side. There's no free lunch.

I built a VW buggie with a Paxton SC on it which was a blast, but blew one of the jugs off after a season. It was designed for a 300CI engine, and I had it on a 2200cc engine -- oops.

When I look at piston aircraft turbo systems, common failures include exhaust cracks/leaks (which are very expensive due to the more expensive materials they're made from), turbo controller failures, wastegate failures, and the turbos shooting oil into the exhaust which then catches fire.

Superchargers have their own failure potential without a doubt and don't have as simple of operation, so I fully agree there is no free lunch. However, they don't have any of the failure modes I have listed above.

 

[Henning]

Correct. But since airplanes are steady state devices, the energy robbing isn't a big deal since it's always occurring. A properly sized supercharger won't have pump losses when run at an ideal altitude since you'll be at WOT. A turbo will rarely have that, but will always have exhaust backpressure, and turbos tend to heat the induction air more unless an intercooler is used.

The failure modes associated with turbos in aviation engines are making me think superchargers have a lot of advantages. Like I said, both have their advantages depending on the specified operation of the aircraft.

I think stack em. Then have a nitrous kit that sprays nitromethane for the enrichment fuel. That'll cure quiet.

 

[kmead]

One of the noisiest airplanes I have been in was a Paris Jet. I think it was louder on the inside than on the outside. The intercom and air conditioning was inop on that flight.

 

[Ted]

I think stack em. Then have a nitrous kit that sprays nitromethane for the enrichment fuel. That'll cure quiet.

The turbo-supercharger sequential setup would definitely have its benefits. But for a traditional LyContisaur, that would probably only be found to be beneficial if you intended on getting into RVSM airspace.

 

[Henning]

The turbo-supercharger sequential setup would definitely have its benefits. But for a traditional LyContisaur, that would probably only be found to be beneficial if you intended on getting into RVSM airspace.

The spray rig can get you above RVSM airspace.

 

[zaitcev]

I flew both Remos GX and Flight Design CTLS, and both were too loud without headsets. Not as loud as Cherokee and 172, but unfortunately not quiet enough.

 

[RevDMV]

A buddy and I did a new aircraft fly off a few years back. Flew most of the new models available at the time.

Hands down the TB series was the quietest. Next up was the Saratoga TC, I was pretty surprised by how easy it was inside when I pulled the headset.

By far the worst were the SR-20/22, felt like a hammer on my head at take off, even with noise cancelling, wouldn't even think about taking off the headset. I thought it might be due to the composite construction, but the Diamond was more on par with a Cessna for noise, rather than as bad as the Cirrus.

Anyway, short one flight samples and aircraft of course...