A little engine trouble

I was out flying the CAP's 172 yesterday when I noticed the same thing. A
growling sound. I determined that it was the soda can air vents getting hit
by the prop wash, or rather, the openings being hit and the cans amplifying
the sound.

What were you flying and could it have been the same thing?

mike regish

"Peter Duniho" wrote in message
...

I hesitated to even bother writing about this, since so far it seems like
pretty much a non-event. But then I figured, what the heck...hardly
anyone
ever actually writes about actual flying, however mundane, in this
newsgroup, so here you go...

"mike regish" wrote in message
news:QRXyc.95474$Ly.16002@attbi_s01...
I was out flying the CAP's 172 yesterday when I noticed the same thing. A
growling sound. I determined that it was the soda can air vents getting
hit
by the prop wash, or rather, the openings being hit and the cans
amplifying
the sound.

What were you flying and could it have been the same thing?

Nope...the Renegade doesn't have those kinds of vents, and of course the
prop wash is entirely aft of cabin venting anyway.

I'm not ready to rule out some sort of aerodynamic effect -- for one, during
the annual inspection the fiberglass tips of the horizontal stabilizer were
replaced -- but it sure didn't seem like one to me at the time. My instinct
was that it was an engine issue.

Also, with ten years of experience flying the airplane, if it IS an
aerodynamic effect, it's almost certainly something new since the annual
inspection. Obviously I can't say that I've seen every single thing the
airplane could do, but I'll bet I've come pretty close over the years,
especially in what are otherwise normal situations such as this one.

Now that I think of it, another thing that's new is that I had them add a
second comm antenna. The sound happened in a climbing left turn, so I
suppose another possibility is some sort of vibration from the antenna.
I'll have to check into that.

I will, of course, post follow-ups to report what, if anything, I eventually
learn.

Pete

In article QRXyc.95474$Ly.16002@attbi_s01, mike regish wrote:
I was out flying the CAP's 172 yesterday when I noticed the same thing. A
growling sound. I determined that it was the soda can air vents getting hit
by the prop wash, or rather, the openings being hit and the cans amplifying
the sound.

Sometimes odd sounds turn out to be nothing to worry about.

A week ago, I was flying my Ka-8 glider over Andreas village, which is
not far from the airfield. I had just got off a winch launch, and was in
about the first or second thermal, trying to get enough altitude to try
and get out of the area.

I then heard amongst the sound of the wind going past the canopy this
"Bbbbrbrbrrrrrr brrrrrrrrrrr brrbrbrbrbrbrb" sound, which
immediately made me think that it was airframe fabric vibrating in the
wind. It went quiet for a bit. Then I heard it again. Getting a bit
concerned that the glider might have hit something on the launch that
had damaged the fabric, I was thinking of levelling out for a short
while to make a decision.

Then I realised what it was. It was the sound of motorcycles
accelerating up the Sulby straight about three or four miles away...it's
amazing how well sound travels when you're above what's making the
sound.

(The nice thing about the Ka-8 is that I can hear powered aircraft in
the vicinity).

--
Dylan Smith, Castletown, Isle of Man
Flying: http://www.dylansmith.net
Frontier Elite Universe: http://www.alioth.net
"Maintain thine airspeed, lest the ground come up and smite thee"