Author Topic: Is a piston turbo so loud you can hear it from a distance (during landing)?  (Read 3634 times)

Offline Frank N. O.

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I was out on a drive today for the first time in a long while and where else to go but an airport to hope to see an aircraft or two more closely than I normally would. I started at Billund Airport (EKBI) and I saw a landing plane which I at the time thought might be a Piper Saratoga for some reason (as you know I'm not good with Piper names) what struck me was that it almost sounded like a turboprop, I could clearly hear a fair sized turbo spinning over the drone of the low-revving piston engine. After searching for pictures to confirm it was a Saratoga I found out that with a T-Tail it seems to go under the name Lance but otherwise looked pretty much like the plane I saw. Is it really true the turbo on a turbo-normalized piston aircraft engine can be heard so loud or was it perhaps a gasturbine (turboprop) conversion? Btw, to clarify then I was at a stop at the side of the ring-road going around north of the airport and planes landing come in just a few hundred meters above the surface going diagonally across to land so it was fairly close, but I still think that turbine-sound was unusually noticeable.

Frank
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Offline ZK Kiwi

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On some Turboed Piston singles you can indeed hear the Turbo at low power settings - remember the exhaust pipes are only a foot or so long. The other thing that creates a "whistle" which can sometimes sound turbo -like is airflow through the retractable undercarriage - Piper Turbo Arrows definitely do this and I would assume other variants would as well.
There are Turboprop versions of some of these Pipers, however they are extremely rare.
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Offline Frank N. O.

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Thank you for the answers, I hadn't really thought about windhowl from the gear or such, although that does remind me of some cars with similar traits, especially a classic Volvo 240 Estate. Those old 240s also had a direct-drive cooling-fan and when the engine started up it made a wind-roar that could go right thrue a double brick-wall house (our neighbor had one when I was kid and you could always hear when it started).

Frank
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Offline Fabo

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Well I doubt turboprop... you can barely hear turbine on that (unlike jet) - most noise in turboprop comes from actuall propellers - which are quite different from piston props, for obvious reasons.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."