Strange engine noise
Thread Starter
Strange engine noise
An aircraft, sounding much like any other twin jet engined airliner, passed over me yesterday (above cloud - so no ID). Climbing away from a Heathrow departure.
The only way I can really describe what I heard is to say that it sounded just like when a boat's propellor cavitates - revs rise very quickly but no thrust increase, caused by applying too much power at low speed, bit like a wheelspin. This happened three times in rapid succession.
The rpm increase was far quicker than a normal jet engine can. rpm decrease was equally rapid.
Any ideas? I've heard it once before.
The only way I can really describe what I heard is to say that it sounded just like when a boat's propellor cavitates - revs rise very quickly but no thrust increase, caused by applying too much power at low speed, bit like a wheelspin. This happened three times in rapid succession.
The rpm increase was far quicker than a normal jet engine can. rpm decrease was equally rapid.
Any ideas? I've heard it once before.
Well, the first time I heard it while aboard a 146 I thought the pilot was slamming the throttle levers back and forward. It definitely sounds like thrust changes but is in fact airflow separation as the flaps move through a particular position.
Thread Starter
I suppose I'll just have to wait until I hear it again on a clear day, and can give a type.
Why would a 146, at several thousand feet, on departure and 25 miles from takeoff, be playing with flaps?
As I said earlier, I'm positive it was engines - there was a clear absence of engine noise in between the 'runaways'.
Why would a 146, at several thousand feet, on departure and 25 miles from takeoff, be playing with flaps?
As I said earlier, I'm positive it was engines - there was a clear absence of engine noise in between the 'runaways'.
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Why would a 146, at several thousand feet, on departure and 25 miles from takeoff, be playing with flaps?
Never heard jet engines cavitating and never suffered that kind of pretty critical situation.
Thread Starter
I live a few miles South of Dorking, and a few miles North of Gatwick's airspace.
I normally have descents into Heathrow, but if on Easterlies, I get the West bound traffic cruising or climbing gently.
I didn't say that the engine was cavitating, it was an analogy which a boat user might understand. The engine rpm rose far more quickly than normal. I wondered if I was hearing a compressor stall, or some other precursor to the demise of my local school/hospital.
I normally have descents into Heathrow, but if on Easterlies, I get the West bound traffic cruising or climbing gently.
I didn't say that the engine was cavitating, it was an analogy which a boat user might understand. The engine rpm rose far more quickly than normal. I wondered if I was hearing a compressor stall, or some other precursor to the demise of my local school/hospital.
