access-air
Posts: 1576
Joined: Thu Sep 21, 2000 5:30 pm

Wht Makes The RR Dart Turboprop Scream?

Mon Dec 11, 2000 4:33 am

Does anyone know that answer to this question?????
I keep getting the same answers...either "I dont know" or the gearbox....if it is the gearbox, why?????? and are there any other contributing factors??????
Also, as the Dart is my fave turboprop engine, I must say that i hate the "hushkit" of sorts that some companies put on the enlet ring to deaden the scream.. 
Oh and inflight what is it that makes that higher crying sound...esp if youre seated in the middle of the aircraft (F27) that comes from the engine???? apart from the usually propbuzz/hum sound........also, there are three different sideline sounds for say the F27 sounds based on prop shape.......12foot round props have shwoosh sound, flat tipped 11.5 foot props have an ordinary sound to them, and the pointed 12.5 props like on the FH227 make a more sharp and loud sound....can this be explained too???????

Aint I a pian in the hiney????

Access-Air
Remember, Wherever you go, there you are!!!!
 
Guest

RE: Wht Makes The RR Dart Turboprop Scream?

Mon Dec 11, 2000 11:44 am

It's gotta be from the turbine.

As I recall that engine used RPM to make power
over sheer torque. If I remember right it runs in
a pretty high RPM range. When they taught us
about the airplane it included a discussion on
the prop/powerplant workings. It was mentioned
that before the engine allowed more prop pitch
it would accelerate first - which supports an
RPM over torque design.

I flew the thing, both F-27's and FH-227's, for a
couple of years... it was nicknamed: "The Whistle Pig"

Joe
 
Greeneyes53787
Posts: 817
Joined: Tue Aug 08, 2000 10:34 am

RE: Wht Makes The RR Dart Turboprop Scream?

Tue Dec 12, 2000 7:13 am

AIR
 
Guest

RE: Wht Makes The RR Dart Turboprop Scream?

Wed Dec 13, 2000 12:08 am

The Dart is probably a single shaft engine and has to run at
near 100% RPM, even at idle power. The engine in the MU-2
is the same, very noisy.
 
crjmech
Posts: 257
Joined: Wed Jun 07, 2000 6:31 am

RE: Wht Makes The RR Dart Turboprop Scream?

Wed Dec 13, 2000 9:28 am

The RR Dart is indeed a single-spool engine like the Garrett TPE331 found on MU-2s, Jetstream 31/32/41 and Turbine Commanders. I think the high noise levels of such engines are due to the high speed of the reduction gearbox. Free turbine engines turn their gearboxes at lower speeds, whereas the single shaft engine drives the gearbox at whatever the engine RPM is at the time. Just a semi-educated guess (I'm a mechanic, not an engineer), but I've always found single shaft engines to be much louder than their free turbine brethren.
Thou shalt mind thine altitude,lest the ground reach up and smite thee.
 
access-air
Posts: 1576
Joined: Thu Sep 21, 2000 5:30 pm

RE: Wht Makes The RR Dart Turboprop Scream?

Wed Dec 13, 2000 10:08 am

Joe,
Thanks for you answer......
what airline did you fly for????
Im doing a website on the FH-227.
now i know what to call it!!!!!
The Whistle Pig!!!!!!!
I love it!!!!!!!!! staye tuned for the URL to my website

Access-Air
Remember, Wherever you go, there you are!!!!
 
Greeneyes53787
Posts: 817
Joined: Tue Aug 08, 2000 10:34 am

RE: Wht Makes The RR Dart Turboprop Scream?

Thu Dec 14, 2000 5:14 am

I appreciate this engine too. The combination of the Dart and Dowty Rotol (sp) propellers make the Convair 600 a well-powered plane. The Vickers Viscount was ahead of its time but was a bit loud. The F-27, the first aircraft I ever sat in the cockpit of, is an ahead-thinking type with the high wing and other features. I like that one too.

G
 
Guest

RE: Wht Makes The RR Dart Turboprop Scream?

Thu Dec 14, 2000 6:29 am

" The combination of the Dart and Dowty Rotol (sp) propellers make the
Convair 600 a well-powered plane."

Do you really think so, Greeneyes? I think the 600 is a sissy's Convair. Why settle for the Dart powered CVR (2750 eshp) when you could have a REAL Allison 501 D-13 powered Convair 580 (4300 eshp). Also, North Central Airlines and Frontier both passed on the Dart powered Convair because it was underpowered.

Concur with the Dart turning at high speeds. It's a very narrow intake to begin with and it runs on the mass through turbine principle--which means the mass of air through the turbine must be proportional to prop speed.

Also, as I recall, the DOWTY's must spin at a very high speed on the ground--in other words, the HPCs must be out of cruise lock. I think the prop is spinning at greater than 1100 RPM even on the ground.

The same guiding principle (pitch control) also applied to the Convair's Allisons. The Allisons rumble louder than the Dart with a deeper whistle probably due to the larger intake. Also the 501's reduction gear assembly is well forward of the power section. Is this also true of the Dart? Even static on the ground, the Hamilton Standards on the Convair, had to spin rapidly. It's also worthy to note that on setting the take off power on the Convair, you had to advance the power slowly and evenly. Do so too quickly and the pitch would go into autofeather.

 
Guest

RE: Wht Makes The RR Dart Turboprop Scream?

Thu Dec 14, 2000 6:36 am

As you can tell, I'm big on the Allison engine (not to say that the Dart is bad--because it was WAY ahead of its time).

But did you know that the Allison 501--the same basic engine used to power the Lockheed Electra, C-130, P-3, Super Guppy....is also used to power Navy Ships? The 501 series K (essentially the same basic aerospace egine without the prop and cowling) is used to power Arleigh Burke Class destroyers!

Does anyone know if the Dart is being used in similar situations?

Just a little digression.
 
access-air
Posts: 1576
Joined: Thu Sep 21, 2000 5:30 pm

RE: Wht Makes The RR Dart Turboprop Scream?

Thu Dec 14, 2000 7:10 am

I have a RR Dart Manual supplied to me by an ex-Ozark mechanic......and actually the reduction gearbox is right behind the propeller hub just inside the inlet....and then it goes straight back to the compressor stage...it isnt a separate structure like that of the Allison......I will agree that the Allison engine has tremendous power but to me the Dart will always be dear to my heart!!!!!
I grew up as a small child listening to Ozark FH-227Bs in my little town......had I lived north in Wisconsin someplace i would have probably been a Convair 580/Allison nut.....but.....i guess there is no definitave answer as to why they whistle/scream/screach what ever you want to call it......i just love it..... 

Access-Air
Remember, Wherever you go, there you are!!!!
 
Guest

Access-Air

Fri Dec 15, 2000 3:43 am

So, you're the guy who is putting together a F-27 site. Weren't you looking for photographs?

I have a photograph of my Grandparents in front of a Delta Fairchild F-27 in Montpelier New Hampshire--taken in the early 70s. I can probably get it scanned and sent to you by the end of the month if you're interested. I'll shoot you an e-mail if you are.
 
Greeneyes53787
Posts: 817
Joined: Tue Aug 08, 2000 10:34 am

RE: DC-9APT

Fri Dec 15, 2000 10:44 am

Hello friend.

I much prefer the 580 to the 600. I think the Allison is one of the best engines ever built. In fact the GM/Convair connection goes back to the Turboliner which was introduced just after WWII. And I think the 580 is probably the greatest twin turboprop ever made- without any doubt in my mind. This is one of the best greaser craft of the century and beyond.

But the Dart engine was the subject at hand. I just wanted to contribute without competing.

But also, I have footage of a 600 taking off at SAN where it gets up about 500' before where most aircraft begin their t.o. roll. The 600 is not underpowered, as I see it. But the 580 is overpowered.

A good example of the great power of the Allison is the Convair Pogo which was powered by a single Allison engine with counterrotating propeller blades. This engine easily lifts the whole aircraft straight up and then pushes it about 500 (plus) mph. No, the Allison is not dull nor slow. I know.

But at immediate power from a stop- a 340 is difficult to beat. But when the 340 is finished the 580 is just beginning- and then some. Yep.

Next time you're flying a 580 to Lexington please tell me. I'd love a fly around the city in it.

G
 
access-air
Posts: 1576
Joined: Thu Sep 21, 2000 5:30 pm

RE: Access-Air

Fri Dec 15, 2000 7:46 pm

Sure!!!!

Id be happy to get ahold of any FH-227 picture if possible....esp if its Delta.....I am always looking for Delta FH-227s...altho i think only two ever made it into full DL colours N376NE and N378NE........the rest were put into storage....as far as i know.......until sold to Air New England.....but anyway...sure Id love to see it...and if possible id Love to add it into my website....with full credit given to the photgrapher....if not id stilllove to have the photo just to see an FH227 at MPV...... 
and Yes im the Fairchild Nut...always have been sicne Ozark was flying theminto my city here.......in my opinion it was one of the best........the biggest of the Fokker/Fairchild F27 sereis... 
Anyway sure go ahead and send it id appreciate it very much... 

thank you.... Access_air
Remember, Wherever you go, there you are!!!!
 
Qantas737
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RE: Wht Makes The RR Dart Turboprop Scream?

Fri Dec 15, 2000 9:08 pm

yeah access, your a pain in the hiney, hehe. Anyway if it makes a squeeling noise my guess is that it is the turbo making the scream! I know that in a car the turbo makes it sound lots cooler with the scream and a blow off valve will top it off with a good noise when decelarating or changing gears. Anyway im no expert!  
 
tom2katie
Posts: 79
Joined: Sat Nov 11, 2000 8:58 pm

RE: Wht Makes The RR Dart Turboprop Scream?

Sun Dec 17, 2000 3:44 pm

A 580's prop only turns 1080 RPM's. The engine turns at 14820 and goes through a very large reduction. As to the Dart noise, it is mostly from the reduction gear box. The curse of the single shaft turbines. An autofeather would only occur on a CV-580 on takeoff if the NTS sensed a big torque split. Rapid power lever movement wouldn't do it unless they were misrigged. But slow power lever movement is always a good idea regardless. Long live the Convair. What a fantastic airplane. The ones I work on have nearly 180,000 cycles. Show me a newgen aircraft capable of that...
 
Guest

Tom2Katie

Mon Dec 18, 2000 12:03 am

Do you work for ERA, by chance?
 
tom2katie
Posts: 79
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RE: Wht Makes The RR Dart Turboprop Scream?

Mon Dec 18, 2000 11:18 am

dc9 capt.. good guess.. ERA is about the only one still flying people on the grand old 580. You are familiar with them I take it?
 
Guest

RE: Wht Makes The RR Dart Turboprop Scream?

Tue Dec 19, 2000 9:53 am

The screaming sound you hear from the RR Dart and Garrett turbo-prop engines is the compessor. These engines have a centrifugal (centrifical) compressor. Have you ever noticed the scream from the APU on B-737, Electras, Hercs, CV-580s, etc? These engines all have centrifugal compressors. The wonderfull Allison 501 series engines have axial flow compessors.
With a centrifugal compessor the air is drawn into the centre of the compessor (a rotating disk with radial vanes) and slung outward by centrifical force, then is compressed in the plenum as more air is forced in from the compressor. if it has a second compressor stage it will flow from the plenum into the centre of the second stage compressor, then get flung out again into a second plenum then on into the burner section where fuel is added and burned, the expanding gas flows out to drive the turbine(s). In order for a centrifugal compessor to work it has to turn a very high speed, maybe 30.000rpm, causing the well known scream.
With axial flow compessors, there will be multiple stages of blades (airfoils) mounted on a shaft that rotates. In each stage the blades are shorter than the stage before and the compressor housing also narrows down in order to maintain the blade tip clearance and therefor maintains the compession. Axial compessors are able to run at lower speeds = less noise.
Allison 501 series engines have a 14 stage compressor and the engine can operate at 2 speeds, normal is 13,820 rpm and low speed ground idle is in the range of 9,900 to 10,300 rpm.
Now I will confuse the issue a bit, the RR Dart, Garrett TPE, and the Allison 501 all operate at basically 1 speed and are primarily controlled by prop pitch, with some sort of associated fuel control to ensure that the correct amount of fuel is available.
Then there is the Pratt & Whitney PT-6 series engine that has both axial and centrifugal stages in it's compessor.
This is a Sesame Street version of gas turbine engine compressors, RR published an excellent book on gas turbine engines called "The Jet Engine".
I hope this helps.  
 
access-air
Posts: 1576
Joined: Thu Sep 21, 2000 5:30 pm

RE: Wht Makes The RR Dart Turboprop Scream?

Sun Dec 24, 2000 9:05 pm

I would like to thank each and every person that has contributed in helping me answer my question!
Have a wonderful Holiday!!!!

Access-Air
Remember, Wherever you go, there you are!!!!
 
access-air
Posts: 1576
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RE: Wht Makes The RR Dart Turboprop Scream?

Tue Nov 02, 2004 5:36 am

For all of you that have not seen it yet, the URL to my website called
"The WhistlePig" is http://fh227.rwy34.com

Cheers, Access-Air
Remember, Wherever you go, there you are!!!!
 
pilotpip
Posts: 2820
Joined: Fri Sep 19, 2003 3:26 pm

RE: Wht Makes The RR Dart Turboprop Scream?

Tue Nov 02, 2004 11:49 am

If not ERA, IFL maybe. Convairs are neat airplanes. Especially the 5800s that have the extra fuselage plugs in front and behind the wing spar, and EFIS!!

Makin' an old bird soar again. I dig those things. Except of course, when they don't have pressure refueling capabilities.  Smile
DMI
 
411A
Posts: 1788
Joined: Mon Nov 12, 2001 10:34 am

RE: Wht Makes The RR Dart Turboprop Scream?

Tue Nov 02, 2004 12:07 pm

While ElectraMan has correctly identified the rather loud noise emitted from the RR Dart engine (on the ground) as coming from the COMPRESSOR (not the reduction gearbox), he is quite incorrect in presuming that the Dart engine turns at a constant speed.
It most certainly does not.
Take for example the RDa.7 series fitted to the F.27 Mark 400 and the FH227B.

Takeoff RPM (wet or dry power) 15,000

Climb RPM 14,500

Alternate (normal) climb RPM 14,200... 755 EGT (or) 730 EGT (longer turbine blade life.

Normal cruise RPM 14,200....730 EGT

Descent RPM 12,500, which varies according to the pilots selection.
Note: some models of the F.27 specify that the speed band of 12,600-13,700 RPM shall not be used due to excessive airframe vibration.
The Viscount is similar.

Ground ops RPM 11,000 (at this speed it is the loudest)

 
greasespot
Posts: 2955
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RE: Wht Makes The RR Dart Turboprop Scream?

Tue Nov 02, 2004 12:25 pm

Hate to break it to all. The scream comes mostly from the superchargers. When our component shop is testing them they soud just like the scream from the Darts. A dart on a test cell(with out superchargers) sounds way different than one istalled on an aircraft.

GS
Sometimes all you can do is look them in the eye and ask " how much did your mom drink when she was pregnant with you?"
 
411A
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RE: Wht Makes The RR Dart Turboprop Scream?

Tue Nov 02, 2004 3:33 pm

Actually, Greasespot, I would disagree.
I have been to RR Darby and have watched/listened to Dart engines on the test stand, with and without the cabin superchargers (Roots blowers), and they have been just as noisey...altho would agree that with the spill valves open, as they normally would be on the ground, indeed the blowers contribute to the howl, but a different pitch than the engine compressor.
Also, DC6/DC7 aircraft have cabin superchargers nearly identical to the units on Dart engines, and they make about the same noise, altho, due to the rumble of the piston engines, it is not so noticeable.

In addition, to continue with my comments above about the engine speed, the throttles control both the engine RPM and fuel flow.
The fuel flow is fine-tuned with the 'fuel trimmers'. These are electric switches that set the engine fuel control unit according to pressure altitude/outside air temperature for takeoff, and also adjust the EGT during climb/cruise to the desired temperature.
The Dart is a very rugged and reliable turbine engine, but of course, by todays standards, not so fuel efficient.
 
efohdee
Posts: 212
Joined: Fri Oct 29, 2004 4:52 am

RE: Wht Makes The RR Dart Turboprop Scream?

Wed Nov 03, 2004 5:31 am

I agree with Electra Man, the scream comes from the first compressor stage. The Dart has just a single spool two stage compressors, both centrifugal. Therefore the compressor that is directly exposed to the outside makes all the noise. In other words your ear has a straight shot at the first stage compressor, which is turning at very high speed. Other single spool engines have the same characteristic. The T-62 APU, and a lot of early turbojets like the J-33, J-34, and J-47 are the same way. You will lose your hearing. More modern dual spool engines, the first stage compressor is turning much slower and the high speed compressor is "shielded" by this low speed compressor. This is also why turbofans are quieter.
 
airplay
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RE: Wht Makes The RR Dart Turboprop Scream?

Wed Nov 03, 2004 2:18 pm

Compressor noise makes the sound like many have said. The supercharger makes some noise too, but it is quite drowned out by the compressor noise.

It is a single spool turbine but is certainly not like a Garrett as far as speed. the engine operating range is about 10,000RPM to 15,000RPM and the gearbox has a 10:1 reduction.

There is a hush kit available for some Dart powered aircraft. It consists of a reshaped intake that sits a little closer to the prop.

ERA is about the only one still flying people on the grand old 580

There are a few running in Canada still as well.

 
commutrcapt
Posts: 1
Joined: Mon Dec 05, 2011 9:31 pm

RE: Wht Makes The RR Dart Turboprop Scream?

Tue Dec 06, 2011 12:52 am

It's really interesting reading everybody's different take on the "Dart Scream". Electra Man and 411A have between them got most of the puzzle, but here are a couple more pieces to complete the picture. If you walk around an F-27, YS-11, or CV-600 running on the ground, you'll notice a significant change in the pitch and intensity of the scream. That's because the intake duct is an almost acoustically-perfect megaphone radiating the siren song of the centrifugal compressor forward. High frequencies are highly directional. Once you're aft of the plane of the propeller, you begin to pick up the equally shrill but slightly more ragged howl of the Rootes blowers (aka cabin superchargers). These also are the culprits for the "high crying sound" mid-cabin mentioned by Access Air. Progressing further aft, the slightly lower-pitched moan of the final stage power turbine can be heard through the torchy roar of the exhaust stacks.

As for engine and prop speeds, our Darts (Fokker-27 Mk 400 - Don't remember the engine model) didn't have independently controlled prop governers. The prop governers were connected by a fussy and intricate linkage to the power lever connection on the fuel control, which through cams and levers created a non-linear programmed relationship between throttle position and prop speed. Constantly needed tweaking. Lot's of 3 am ground runs. Lots of irate neighbors.

An for DC-9 CAPT, your grandparents in front of the Delta FH-227 must have been in Montpelier VERMONT or MANCHESTER NH. NH doesn't have a Montpelier. The 227 was always a tight fit at MPV due to rising terrain and single-engine climb gradient, making for load-limited takeoffs and frequent overflights to BTV. Sometimes pasengers would be denied boarding, and even thru passengers deplaned if the temp rose and the wind shifted while the plane was on the ground. A little overweight, a little underpower = Poorly Integrated Groundlover or PIG for short. Summer takeoffs sometimes were real nail-biters for the spectators, not to mentiom the crews.
 
26point2
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RE: Wht Makes The RR Dart Turboprop Scream?

Tue Dec 06, 2011 1:53 pm

Quoting Electra Man (Reply 17):
The screaming sound you hear from the RR Dart and Garrett turbo-prop engines is the compessor.

This is correct. I flew the Garrett TPE 331 equipped Turbo Commander for 13 years. The loud scream was only at ground/low idle. At high RPMs it was much less noticeable and there is no "scream" when the plane is airborne.

We would often get the "Garrett Salute" when entering an FBO ramp....insert middle fingers into ears.
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Wht Makes The RR Dart Turboprop Scream?

Tue Dec 06, 2011 10:13 pm

I thought it was the screaming banshee inserted by the good folks at Rolls-Royce at the factory   

Seriously, the Convair 640 takes the cake for ramp screamers    I think I had hearing loss a couple of days afterwards after mashalling one, even wearing proper hearing protection (24db passive noise reduction, basically David Clark headsets with no speakers in them).
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
Pihero
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RE: Wht Makes The RR Dart Turboprop Scream?

Tue Dec 06, 2011 11:53 pm

Quoting Greeneyes53787 (Reply 6):
The combination of the Dart and Dowty Rotol (sp) propellers make the Convair 600 a well-powered plane.

Yes, it was, and it was my first machmeter-equipped aircraft. Flew it for 18 months in North Africa and the Sahara desert and it was one hell of an aircraft, very comfy and an delight to fly .
As ElectraMan and others have said, most of the noise comes from the centrifugal compressor, which has TWO stages... and the scream indicates that the pilot had correctly selected the "Ground taxi " pitch with the large paddle switch. Failure to do so would rather quickly over-torque the engine and cook it. I remember tha during the type-rating ground course, a 100% mark on the propeller exam was mandatory.
Until quite recently, there was a DHL Convair based in Nice andf it used to trigger some very good memories in the nostalgy mind.
Contrail designer
 
113312
Posts: 583
Joined: Sat Apr 16, 2005 9:09 am

RE: Wht Makes The RR Dart Turboprop Scream?

Wed Dec 07, 2011 1:13 am

I have to concur with Greaspot. The Darts have lots of accessories driven by the engine via a drive-shaft. Each engine in the Fairchild operate a 4 cyl mechanical air compressor, a Roots air compressor for cabin pressurization, and a number of electrical generators and other items. These mechanical devices all run at various speeds depending upon the speed of the engine from the lowest ground idle, to taxi range to takeoff speed. Thus, these devices emit sounds of various pitch related to the speed of the engine just as the engine itself.

The well known shriek at low rpm is mostly attributed to the accessories. As stated, if the core engine is run without the drive shaft attached or in a test cell, the sound of the engine is quite different than heard in line operations with everything working.

Certainly, the compressor of the engine makes noise as all centrifugal compressors will. But the distinctive sounds of the Rolls Royce Dart have a significant contribution from the mechanical air compressors for the pneumatic and pressurization systems.

BTW, the RPM ranges listed in prior threads are the RPM of the engine and not of the propeller.
 
jetstar
Posts: 1370
Joined: Mon May 19, 2003 2:16 am

RE: Wht Makes The RR Dart Turboprop Scream?

Thu Dec 08, 2011 1:44 am

At my first corporate job in 1970, we operated a G1 in addition to the JetStar and I can tell you first hand the screaming noise came from the compressor. Many times when our G1 taxied straight in to the ramp, the noise was unbearable, especially during the warm months when the hangar doors were open not only for me but for all the other mechanics working in the hangar, when the G1 turned 90 degrees to park the noise was much lower as the compressor was not aimed straight at the hangar. If I had time I would grab my ear protectors, but sometimes I did not have time to run back to the shop so even with my fingers in my ears, the noise was unbearable. Sometimes the line crew would have the airplane taxi straight in right up to the door threshold and almost everyone in the hangar would stop working and either run into their shops or just stand there with their fingers in their ears. Even with the hangar doors closed, the noise was very loud as the airplanes neared the doors.

In addition to our G1, there were 2 other G1’s and 2 F-27’s based in our hangar and in the hangar adjoining our hangar, the companies there had 3 F-27’s and a G1 so you could imagine all the noise we had to put up with during the day. I think the permanent ringing in my ears was partially caused by all these RR Dart powered airplanes, in addition to the noise from all the early jets taking off like the LearJets, Jet Commanders, JetStars and even the G2 and G3, they were all loud noise makers and our hangar was only about 700 feet from the mid point part of the runway

My memory might be foggy on this thinking back 40 years ago, but I think only the left engine on the G1 had the Roots Blower, and I don’t remember any difference in noise from the left or right engine.

I not really sure but I believe on the F-27 the air compressor was electrically powered, the company that had 3 F-27’s had a similar unit mounted on a cart to use in the hangar to supply air to the pneumatic hydraulic system and although it was noisy when they ran it, it was nowhere near the noise from the compressor on the Dart engine.

I don’t remember any real difference in engine noise between the G1 and the F-27, to me they both sounded the same and I heard these 2 airplanes almost every day for over 6 years during my time there, first as a mechanic for a repair shop and then my corporate job, both jobs were in the same hangar.

JetStar
 
dandaire
Posts: 62
Joined: Fri Jul 11, 2008 9:16 am

RE: Wht Makes The RR Dart Turboprop Scream?

Thu Dec 08, 2011 4:36 pm

Quoting Access-Air (Thread starter):
Does anyone know that answer to this question?????

According to the following website.

http://www.vickersviscount.net/Pages_Technical/Technical.aspx


"The noise you hear from a Dart engine is the high pitched whine of the low pressure compressor rotating assembly. The reason for the noise is that the tips of the rotating parts are virtually travelling at supersonic speed."
Old age and treachery will triumph over youth and skill.
 
 
packsonflight
Posts: 326
Joined: Tue Jan 12, 2010 2:55 pm

RE: Wht Makes The RR Dart Turboprop Scream?

Fri Dec 09, 2011 5:00 pm

The distinctive noise from the Dart comes from the air duct that sits right below the air intake. I think it is for the oil cooler or something like that.
The clearance between the duct and the propeller is so narrow that the airflow is "disturbed" by the propeller.

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