Roost Air Lounge => The Classroom => Topic started by: Frank N. O. on January 29, 2009, 12:20:39 AM
Title: Is a piston turbo so loud you can hear it from a distance (during landing)?
Post by: Frank N. O. on January 29, 2009, 12:20:39 AM
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
Title: Re: Is a piston turbo so loud you can hear it from a distance (during landing)?
Post by: ZK Kiwi on January 29, 2009, 09:41:52 PM
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.
Title: Re: Is a piston turbo so loud you can hear it from a distance (during landing)?
Post by: Frank N. O. on January 30, 2009, 02:28:32 PM
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
Title: Re: Is a piston turbo so loud you can hear it from a distance (during landing)?
Post by: Fabo on January 30, 2009, 10:00:06 PM
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.
