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Does your plane whistle?

Bryan Wood

Bryan Wood

Well Known Member
I've been told that my 9A whistles when entering the pattern by numerous people. The only planes that I've ever heard that whistle are Comanches when they are in the landing configuration and I have often been curious what mine sounded like. Well, given enough patience and all of the information that trades on these forums and now I have my answer. "Matthew" posted a video of his wife strafing an airport in their 9a and there is a pronounced whistle as the plane passes. So now the question is, do the other RV's whistle too? Just curious... (Find his video in the photographs and video forums.)

Blue Skies,
 
whistle

Bryan,

My 6 whistles at low RPMs, I suspect possibly an induction leak and will be checking for that. Is your whistle audible in the cabin or to observers on the ground? At what RPMS are you entering the pattern? From discussions with an A&P and reading some of the Deakin engine articles an induction leak is noticeable at low RPM and usually disappears, or isn't audible, when throttle is added. You may, on the other hand, have a whistle from windflow or aerodynamics of some sort if it is not a low Rpm situation? Any thoughts? I am certainly not an engineer, just sharing some thoughts.
 
Bryan,

My 9a doesn't know the words either!!

I have been told mine whistles in the pattern and a Lockhart, Tx friend's 9a also whistles. Must be a characteristic of this airframe.

If I remember correctly, the Lockhart friend (Ted are you listening) did some testing and said it was coming from the openings over the elevator hinges??!!

Cheers,

db
 
whistle

The elevator hinges would also make the whistle even more similar to the Comanche which has a couple of holes on the top of the stabilator where attach bolts of some sort are. I've been told that the whistle goes away if caps are snapped into these holes.

As for my plane compared to Matthews, using information on his autosignature... His, tip up, Catto 3 blade, 0-320, and mine is a slider, Hartzell, 0-320. It seems like the canopy or props aren't the culprit. Just curious.

Doesn't know the words? Now that's funny!
 
Couldn't you do something like set up a high speed idustrial fan at different stations on the airframe to determine the source of the source of the noise?

I know that some leaf blowers (assuming you don't live in the Cali counties where they're outlawed like crack :eek: ) will blow at 200+ miles per hour if you believe their marketing literature. May generate some stares at the airport but it's just a thought.
 
that whistle you are hearing is coming from a source of drag on your airframe. eliminate the whistle and you could have a more efficient aircraft. have you listened to the old cubs, tri-pacers, t-carts etc, they all whistle when at low power and slow flying.
 
Turbine sounding

Bryan,

You obviously heard it on my plane in the video.. and several people have commented that it sounds like a turbine when I fly over. A couple of people threw out the theory that it was my round inlets on the SJ cowl. I kinda thought it might be my gear leg fairings whistling since I don't have intersection fairings on, but maybe that isn't right either. It isn't audible from the cockpit.
 
The "whistle" in Matthew's video sounds like an efficient wing doing its work to me. If you hear a higher pitch whistle it would suggest a drag producer as mentioned by brules, but that turbine like sound is simply the pressure wave coming off of the wing.

Ever hear a high performance glider do a high speed pass? It makes a more intense version of that sound mostly because there's no rumble from the engine interfering. The cleanness of the SJ cowl probably does add to the effect too since there isn't air spilling from the inlets that makes some noise of its own.

Other RV's are going to make less of this sound than the 9/9A's because of their lower aspect ratio wings.
 
Another thing to look into might be any cool air blast tubes that you may have installed. A friend decided he needed more air to his avionics, and used one of the typical corregated plastic hoses that Van's sells, hooked into his NACA vent. At about 100 kts, the loudest whistle you ever heard came from that hose, which is of course inside the cockpit :D

Once he was back on the ground (and the laughter subsided), we blew a leaf blower through one of those tubes. Sure enough, it whistled like crazy. We ended up squeezing the end into a different shape with a tywrap, and it stopped.

After that day, I wondered how much whistling comes from those same type hoses when they're used as blast tubes under the cowling. I've never heard it, but I would bet that it would be almost easier to hear from the ground, than in the cockpit. Also, you would only tend to hear it when the engine noise was reduced, such as landing.

Just something else to consider.

Cheers,
Rusty
 
not so in my case as I don't have any blast tubes. Hey.. if my plane sounds like it is turbined powered.. GREAT! :D
 
The whistler

I have a friend that has a whistling 9A. When he flies over it sounds like a turbine. Sort of cool. I am working on a whistler of my own, maybe this summer it'l whistle.
mvc008f3rs.jpg

am trying to enter a picture of my RV9-A
We will see how this works
51HS
 
whistle

I have been told my Nine sounds like a turbine in the pattern. I can just barely hear it in the cabin. Must be a characteristic of the Nine. My Six never did it. Gerry Chancey, RV-9, N92GC & Cub NC88583
 
My 9A no longer whistle

I have been flying my 9A for almost two years. Everyone in my home field can tell that I entered pattern by the whistling sound. Of course, I can not hear it in the cockpit. I read from the forum that all 9/A whistle. A week or so ago, Alfio, a 9 builder from Canada email me his theory. He bet that the sound comes from elevator rod end bearing slots. I taped mine using duct tape and the whistle went away. This morning I went to a RV fly-in and asked RV pilots on the ground to hear the whistle. None of them heard the sound. Mystery solved.

When I reviewed the past postings, actually from this thread, db1yg stated:

If I remember correctly, the Lockhart friend (Ted are you listening) did some testing and said it was coming from the openings over the elevator hinges??!!
Click to expand...

His friend Ted did it already. Here I second his finding.
 
Horizontal stab

I have been told that the holes in the tip rib of the horizontal stab is the cause of the whistle. Cover the lightning holes with aluminum tape ant the whistle should stop.
 
It's not the tip rib holes. I covered mine as I built to help keep out wasps and such. And yes, it whistles. I've gotten used to the comment "Heard you fly over yesterday" or some such. Doesn't bother me a bit and no, I can't hear it inside. Must be coming from somewhere in the tail. Will try the tape trick.

Bob Kelly
 
No, not the HS tip holes

Same as Bob, my tip rib holes are glassed in. Somehow only 9/As have the whistle sound.
 
Wow, this thread was started before my first flight and has now come back!
I had the same issue and solved it over a year ago by putting a little of that UMHV (?) kinda see through abrasion tape over the hinge cutouts for the horizontal and vertical. You can still see through it to check your bolts for preflight and is basically unnoticeable until you look closely.
Those spaces seem to be ideal for creating a whistle and maybe the huge empenage on the 9s amplify the effect.
 
I proudly fly a whistling -9A. I see it as a badge of honor :). It is just another thing my Vans, what some would call, station wagon can do that the others can't :). Next thing we're going to hear (most likely from a -8 driver with a little tiny wheel) is that if you can stop the whistle, you'll go x knots faster :)!
 
I proudly fly a whistling -9A. I see it as a badge of honor
Click to expand...

IIRC in WWII, the Japanese referred to the Corsair as "Whistling Death".

Not bad company for you -9 drivers:D
 
Take a look at the mouthpiece of a real flute and then look at the hinge cutout on the elevator and rudder -- they are surprisingly similar. I suspect the long straight shape of the -9 elevator makes it a good resonator.
 
Another speed mod!

scard said:
Next thing we're going to hear is that if you can stop the whistle, you'll go x knots faster :)!
Click to expand...

Right on, Scott! I think I saw it documented once that it'll give you and extra .0002 knots! Right up there with putting helium in your tires to keep your empty weight down. Of course the downside of that is that is your airplane wants to fly inverted.

Bob Kelly
 
Whistles sound good!

I live under an airport pattern. Whistling airplanes sound cool, so leave them alone! :)

L.Adamson
 
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