Every gun makes its own tune.

Clint Eastwood said that line in "The good, the bad, and the Ugly" when he heard Tuco's gun...

I had a 79 182RG that had the big two blade prop and the six cyl Lyc in it. The dual exhausts and the big prop had a unique sound. I would do a circle around my house to alert the wife that I was home and to meet me at the airport and she always said she knew right away that it was my airplane (flat pitch and high power probably helped ). Once I loaned it to a friend and told him to do a right hand circle 8 DME out of Waterville and I would meet him at the airport. My wife and I were working in the yard and the RG flew over and I hadn't really noticed it, but my wife said.. "Bill is back, there's your airplane", looked up and there he was. Then I knew why she could always recognize the sound. It was distinct. Lots of prop noise mixed with a pretty abrupt exhaust note...

Well, yesterday I was going out to lunch and as I stepped out of the building I could hear the loud and distinct sound of an airplane taking off (we are about 100 yards from the departure end of the runway). Looked up and sure enough there was a 182RG, tucking its bird legs up into the belly and belting out that unique obnoxious note to anybody who was under it. Some things you just don't forget.

A Merlin has a sweet note, and the old six cylinder 172's remind me of a sewing machine, but Blondie was right, Every gun makes its own tune...

 

Some big jets(777s?) decending into ORD near me often will make a very loud "sucking" sound for lack of a better term, very distincive. I think they are throttling down.
What is it that I am hearing?

 

Spoiler deployment, probably...

I hear it in Denver (DIA at DEN), too.

For some reason (?) it seems louder when the temp is in the zero F range or below.

 

Own tune????

Nothing, absolutely nothing, SOUNDS like the Beech Starship that flies over my office 10 or so times a month headed to/from Rocky Mountain airport.

Of course nothing looks like it either...

 

Remember the Phantoms?

I miss them.

 

I believe that sound is from a power change. A lot of stuff flies over our house north of Seattle and many times we hear sort of an " EEyow" sound. heard the same thing when we lived in Auburn and the tin birds were already dirty in the downwind and set up near to turning on base and they would emit that sound. Surge bleed outlet might be it too.

 

I made a lot beer money during the war betting the wooden ear types what kind of airplane took off without going out to look at them. I can always differentiate the sounds of a B-17 versus a B-24 and recognize AT-6's vs. a BT-13, and of course the Merlin but the Spitfire has a distinct note that the Mustang doesn't. Stack design. The ME-109 has a nice sharp bark, too.

 

When I used to live under the approach path to the airport in San Juan, the DC-6s, DC-7s and Connies flying in used to have sound changes about the time they flew over. It looked like they were lowering their flaps and throttling up to compensate. The Connies used to pop and bang like their engines were about to fall apart! I wonder why the similarly-powered DC-7s didn't do that - must have had something to do with their exhaust configuration.

And then, some years later, there was the distinctive howling from the P.R. Air Guard's F-104s!

 

Where I go to school is about a mile from the airport. The fighter jets are taking off basically right over my building. It always amazes me how loud those jets are.

 

Small diameter high velocity engines on the fighters vs large diameter slower turning and moving mass amounts of air for the big tin birds.

 

I hear this yeeoww pitch change also. We live maybe 65/70 nm northwest from CLT right under "Shine",the flightpath corridor so named for the Carolina moon light(shine) by the wags at the FAA I suppose. So the planes are usually fitted with twin engines under the wings and appear to be 380's or 757's types,which correct me if I am wrong are high bypass turbofans and these are the ones that give off the really distinctive pitch changes.
The MD-80 types and what appear to be older 737s without the newer hipass engines do not give this sound effect. It is not the Doppler effect since it occurs at different places on the flight path,when we hear it,sometimes way north of us and other times much farther south,but they are headed due southeast,probably on that busy O'hare to Charlotte run.
I guesstimate they are at flightlevel 6 to 8 and powering down those big spinners and have no idea they are thrilling the earthbound with their high tech music,or maybe they do.

But my favorite plane noise is a P-3 powering up those huge blades for take off or coming off the ramp to the active runway and those guys hitting those throttles to full on and those props go all bite for so much air that that big Lockheed beauty just has to fly fly fly. C-130's can do this too,just as well. They both keep the turbines going the same speed all the time and when they want to go faster they vary the pitch,bite that air more,and the job gets done. But it is noisy all that atmosphere getting disturbed all at once but it is music to my ears. I got to hear it a lot at NAS/NATC PaxRiver in the 60's&70's. I saw a YouTube of a Russian Bear with those counter rotating bladed turbos and that was a musical event too even on an IPad. But a P-3 with those two bands on each wing was some symphony of wind and smoke and sound.
Cheers,
RE
Ps,inside a P-3,especially a C,is pretty quiet kind of like taking the shuttle to Newark,meh.
Pps,I got to ride on the CollinsFoundation B-24 Witchcraft this past Fall and if I can figure it out will post the You tube up,,,now that baby is loud,hand signals only please.

 

Believe it or not, there is a plane that (strangely, I admit) sounds a lot like the Starship...The Lear Fan.

Not like there's lots of either around to make a true comparison.

 

Glad that you wrote that about the B-24. You must have been in the waist because I just finished writing about how noisy, cold, and windy it was there.I laughed when I saw the film " Memphis Belle', I think, when they were in the waist chatting about how scared they were and SWEATING! They were scared and they sweat but you never saw evidence of either.

 

The 'yeoww' sound I'm talking about is way before final, even before downwind, if they do that... no gear down, no flaps down, fairly high altitude still...

I'm still pretty sure they are spoilers or airbrakes (if they have them)...

It is not engines spooling unless they spool up then back down right away.

 

Amazing that you've heard a LearFan... Weren't there only a couple built? None flying now.

Sound similarity would be from the pusher prop I'm guessing.

Piaggio Avanti, too.

 

I only saw it once, and only noticed it due to the sound. I've only ever seen a StarShip but once, and I thought it was the LearFan returning to KOIC.

I the StarShip is rather cool-looking: like a Long EZ on steroids.

 

I just received an answer from an Airfus driver who has also flown Boeings and he only has 4000 hours in the " Euro Trash" ( his words) but he told me what and how the EEYOW sound is generated by spoiler deployment. So, I was 100% rong again. Damn! That's twice now.

 

I've also been aboard that one("Dragon & it's Tail" then). Hanging out the waist gun door listening those big round motors was sublime.

 

I'm roughly 20 mi. from O'Hare if that helps determine what action the plane would be taking. It's a tremendous whoooshhh, a wheezing sound perhaps. Always twin engine widebodies, 777s? Are the Trents different sounding?

 

The reason that the Electra was such a hot performer was all that propwash from those big paddle-bladed props that produced more lift over the relatively short wings. As you said, the idea was to keep engine RPMs up (since turbine engines, and probably moreso for the earlier ones, tend to spool up more slowly than their reciprocating counterparts) and vary prop pitch to change speed.

The AA Electra that crashed into the East River in NYC while landing on a rainy night at La Guardia was the victim of that. The airplane, American's first, had only been delivered 12 days earlier and the pilot, who had just come off of DC-6s, tried to fly the plane the same way as he had the 6. He thottled back too much, the airplane began to sink, and before the engines could spool up again, the airplane was in the drink. The airlines quickly realized that the Electra had to be handled differently on approach!

 

This is a little O/T, but ironically, the same characteristic of turbine engines - relatively slow spool-up on throttle application - is why it took several years for turbine engines to overtake reciprocating engines in the sport of unlimited hydroplane racing!

The first modern turbine-powered boat in the early 80s used the same hull design as its Merlin-powered predecessor. The problem was that when the driver throttled back to go through the corners on the oval course, he'd be out-accelerated on the straightaways because of the slower throttle response. The next generation of boats had design changes to specifically allow them to corner faster without having to throttle back as much, and eventually the turbine boats took over.

If you know what a "skid fin" is on a hydroplane (it acts as a "pivot point" when the boat is turning, which is really a controlled skid), you'll find that today's boats have skid fins that are vastly larger than on boats of 30 years ago - all in the name of faster cornering!

 

The Electra has T56 engines, which are single spool turboprops. Unless you idle it way back down, it maintains full rpm all the time you are flying it since the prop is geared to the engine shaft, if you are at 100% prop speed, you have 100% engine speed. The advantage of that setup is that even when you are at low power the engine is at full rpm, but it isn't using much fuel so it is running a low temperature. It is, however, moving all the air it needs to make big power. When you want more power, since the engine is already at 100% speed, the power comes on as soon as the fuel is added. The result is that the throttle response of a single spool engine is pretty much instantaneous.

With a free turbine or a turbofan or turbojet, you have to spool back up the gas generator up to get power and there can be considerable lag time waiting for things to come up to speed. Most modern engines are free turbine engines, but the old T56 had one big advantage and that was rapid throttle response if the props had RPM's. Newer engines require more time to spool up than older engines.

What you described could happen if you pull power way back and allow the engine to spool down to a low idle setting and let the prop and engine speed degrade. Those engines had pretty dumb controls and they did what you told them to do. So if you put them in the ground idle position they could spoold down, but it shouldn't happen in normal flight and that wasn't the way the engine was designed to be run.

 

Back in my lineman days as a youth, I prided myself that I could tell any plane taking off by the sound. I used to bet an old school A&P man and he was hard to beat....

I went out to the airport the other day and tried to see of I could still do it... humiliation.

 

I stand corrected. Your scenario in the last paragraph sounds like what may have happened to the AA pilot.