Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Wht Makes The RR Dart Turboprop Scream?  
User currently offlineAccess-Air From United States of America, joined Sep 2000, 1939 posts, RR: 12
Posted (13 years 9 months 1 week 6 days 20 hours ago) and read 9385 times:

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!!!!
34 replies: All unread, showing first 25:
 
User currently offlineJoe_R From , joined Dec 1969, posts, RR:
Reply 1, posted (13 years 9 months 1 week 6 days 12 hours ago) and read 8037 times:

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


User currently offlineGreeneyes53787 From United States of America, joined Aug 2000, 844 posts, RR: 0
Reply 2, posted (13 years 9 months 1 week 5 days 17 hours ago) and read 8009 times:

AIR

User currently offlineSHB From , joined Dec 1969, posts, RR:
Reply 3, posted (13 years 9 months 1 week 5 days ago) and read 7995 times:

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.


User currently offlineCrjmech From United States of America, joined Jun 2000, 260 posts, RR: 1
Reply 4, posted (13 years 9 months 1 week 4 days 15 hours ago) and read 7985 times:

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.
User currently offlineAccess-Air From United States of America, joined Sep 2000, 1939 posts, RR: 12
Reply 5, posted (13 years 9 months 1 week 4 days 14 hours ago) and read 7977 times:

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!!!!
User currently offlineGreeneyes53787 From United States of America, joined Aug 2000, 844 posts, RR: 0
Reply 6, posted (13 years 9 months 1 week 3 days 19 hours ago) and read 7967 times:

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


User currently offlineDC-9CAPT From , joined Dec 1969, posts, RR:
Reply 7, posted (13 years 9 months 1 week 3 days 18 hours ago) and read 7963 times:

" 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.



User currently offlineDC-9CAPT From , joined Dec 1969, posts, RR:
Reply 8, posted (13 years 9 months 1 week 3 days 17 hours ago) and read 7958 times:

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.


User currently offlineAccess-Air From United States of America, joined Sep 2000, 1939 posts, RR: 12
Reply 9, posted (13 years 9 months 1 week 3 days 17 hours ago) and read 7956 times:

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!!!!
User currently offlineDC-9CAPT From , joined Dec 1969, posts, RR:
Reply 10, posted (13 years 9 months 1 week 2 days 20 hours ago) and read 7954 times:

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.


User currently offlineGreeneyes53787 From United States of America, joined Aug 2000, 844 posts, RR: 0
Reply 11, posted (13 years 9 months 1 week 2 days 13 hours ago) and read 7944 times:

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


User currently offlineAccess-Air From United States of America, joined Sep 2000, 1939 posts, RR: 12
Reply 12, posted (13 years 9 months 1 week 2 days 4 hours ago) and read 7938 times:

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!!!!
User currently offlineQantas737 From Australia, joined Jul 2000, 738 posts, RR: 4
Reply 13, posted (13 years 9 months 1 week 2 days 3 hours ago) and read 7935 times:

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!  

User currently offlineTom2katie From , joined Dec 1969, posts, RR:
Reply 14, posted (13 years 9 months 1 week 8 hours ago) and read 7923 times:

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...

User currently offlineDC-9CAPT From , joined Dec 1969, posts, RR:
Reply 15, posted (13 years 9 months 1 week ago) and read 7917 times:

Do you work for ERA, by chance?

User currently offlineTom2katie From , joined Dec 1969, posts, RR:
Reply 16, posted (13 years 9 months 6 days 13 hours ago) and read 7909 times:

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?


User currently offlineElectra Man From , joined Dec 1969, posts, RR:
Reply 17, posted (13 years 9 months 5 days 14 hours ago) and read 7896 times:

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.  


User currently offlineAccess-Air From United States of America, joined Sep 2000, 1939 posts, RR: 12
Reply 18, posted (13 years 9 months 3 hours ago) and read 7861 times:

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!!!!
User currently offlineAccess-Air From United States of America, joined Sep 2000, 1939 posts, RR: 12
Reply 19, posted (9 years 10 months 3 weeks 18 hours ago) and read 7814 times:

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!!!!
User currently offlinePilotpip From United States of America, joined Sep 2003, 3150 posts, RR: 11
Reply 20, posted (9 years 10 months 3 weeks 12 hours ago) and read 7695 times:

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
User currently offline411A From United States of America, joined Nov 2001, 1826 posts, RR: 8
Reply 21, posted (9 years 10 months 3 weeks 12 hours ago) and read 7688 times:

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)



User currently offlineGreasespot From Canada, joined Apr 2004, 3084 posts, RR: 20
Reply 22, posted (9 years 10 months 3 weeks 12 hours ago) and read 7686 times:

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?"
User currently offline411A From United States of America, joined Nov 2001, 1826 posts, RR: 8
Reply 23, posted (9 years 10 months 3 weeks 9 hours ago) and read 7648 times:

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.


User currently offlineEfohdee From United States of America, joined Oct 2004, 214 posts, RR: 0
Reply 24, posted (9 years 10 months 2 weeks 6 days 19 hours ago) and read 7573 times:

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.

25 Airplay : 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 i
26 commutrcapt : 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 he
27 26point2 : 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 m
28 Post contains images KELPkid : 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 scr
29 Pihero : 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 a
30 113312 : 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 cy
31 jetstar : 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 compres
32 Post contains links Dandaire : According to the following website. http://www.vickersviscount.net/Pages_Technical/Technical.aspx "The noise you hear from a Dart engine is the high
33 Post contains links Viscount724 : Some good Dart sounds here: http://www.youtube.com/watch?v=Vr63k4ZoT8M http://www.youtube.com/watch?v=Nl8hmxLB3j4&feature=related http://www.youtu
34 packsonflight : 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 t
Top Of Page
Forum Index

Reply To This Topic Wht Makes The RR Dart Turboprop Scream?
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
Does The RR RB-211 535C Have A Deep Roar? posted Sat Apr 15 2006 20:54:04 by 747400sp
Wht Makes The RR Dart Turboprop Scream? posted Sun Dec 10 2000 20:33:40 by Access-Air
Two Different Engine Makes On The Same Aircraft? posted Wed Sep 28 2005 18:57:47 by JAM747
Free-turbine Turboprop - What Makes It Turn? posted Sat Aug 14 2004 18:11:11 by TripleDelta
Who Makes All The Big Sims? posted Wed Oct 23 2002 18:33:04 by Nikes
707-420 & VC10 RR Engines: What's The Difference? posted Wed May 30 2001 05:40:12 by Happy-flier
CFM & RR On The Same Wing! posted Sat May 12 2001 03:00:54 by Bio15
Study With The Job posted Mon Dec 4 2006 06:12:25 by HAWK21M
How Long Was The 757 100 Suppost To Be? posted Sun Dec 3 2006 01:10:58 by 747400sp
Cockpit Emergency Exit On The 744 posted Fri Dec 1 2006 13:54:12 by SK A340

Sponsor Message:
Printer friendly format