Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Why The 3rd 727 Engine  
User currently offlineSAAB340 From United States of America, joined Sep 2001, 320 posts, RR: 2
Posted (12 years 10 months 1 week 4 days 22 hours ago) and read 11751 times:

Hey All!!

Can anyone tell me what the third engine purpose is??

I know this sounds like a dumb question but I really dont know. Thanks

PAUL

40 replies: All unread, showing first 25:
 
User currently offlineBill bob From United States of America, joined Apr 2001, 49 posts, RR: 0
Reply 1, posted (12 years 10 months 1 week 4 days 21 hours ago) and read 11696 times:

Extends its glide when the other two fail. Smile

User currently offlineJetguy From , joined Dec 1969, posts, RR:
Reply 2, posted (12 years 10 months 1 week 4 days 21 hours ago) and read 11690 times:

Not to be flippant, but the -27 has 3 engines because it needs 3 engines. At the time it was the most economical way to get the total amount of thrust to meet the design requirements.

User currently offlineAA777-200 From United States of America, joined Jul 1999, 322 posts, RR: 2
Reply 3, posted (12 years 10 months 1 week 4 days 18 hours ago) and read 11669 times:

cuz it can barely get off the ground with 3 engines. could you imagine it only having 2??? Why do you ask us these questions. Ask boeing. why did the DC10 have 3 engines? why did the MD11 have 3? why does the 747 have 4? Its the design for the plane!!!

User currently offlineMinuteman From United States of America, joined Aug 2000, 271 posts, RR: 0
Reply 4, posted (12 years 10 months 1 week 4 days 18 hours ago) and read 11661 times:

ETOPS didn't exist when they were making the blue prints on the walls of the cave for this plane.


User currently offlineAJ From Australia, joined Nov 1999, 2389 posts, RR: 24
Reply 5, posted (12 years 10 months 1 week 4 days 16 hours ago) and read 11632 times:

During the development of the 727 Boeing was taking input from US airlines. SOme wanted a twin engine aircraft for economy, others four engines for field performance.
The compromise was a three engine aircraft.
Such compromises have also occured on the 747. Pan American wanted a 40 degree sweepback for speed, Boeing a 35 degree sweepback for field performance. The tradeoff? A 37.5 degree sweepback!


User currently offlineCedarjet From United Kingdom, joined May 1999, 8086 posts, RR: 54
Reply 6, posted (12 years 10 months 1 week 4 days 5 hours ago) and read 11586 times:

The 727 is a lot heavier than the 737-200, and remember it was designed in the late 50s and early 60s when engines weren't perceived to be as reliable. Notice that the engine fire buttons are at the top of the centre panel, in later designs they've been moved overhead because of course they're almost never needed, but in those days the prop mentality remained, when it was quite routine for a longhaul prop (Stratocruiser, Connie, DC6 et al) to arrive at the end of a trans-Atlantic or trans-Pacific flight with one engine shut down.


fly Saha Air 707s daily from Tehran's downtown Mehrabad to Mashhad, Kish Island and Ahwaz
User currently offlineGregg From United States of America, joined Jun 2000, 327 posts, RR: 0
Reply 7, posted (12 years 10 months 1 week 3 days 10 hours ago) and read 11538 times:

Also in the early 60s we designed a/c around the enginees, instead of designing engines around the a/c. Most enginees had simular power rating of around 20,000 lbs. So a 707 has 4, the smaller 727 has 3, the smaller 737 has 2 .....

User currently offlineExnonrev From United States of America, joined Oct 1999, 621 posts, RR: 4
Reply 8, posted (12 years 10 months 1 week 3 days 4 hours ago) and read 11519 times:

AJ is right. It was a compromise between American (who wanted two) and Eastern (they wanted four). United was happy with three from the start.

User currently offlineQANTAS747-438 From United States of America, joined Jan 2001, 1935 posts, RR: 2
Reply 9, posted (12 years 10 months 1 week 3 days ago) and read 11497 times:

727 sucks!


My posts/replies are strictly my opinion and not that of any company, organization, or Southwest Airlines.
User currently offlineAJ From Australia, joined Nov 1999, 2389 posts, RR: 24
Reply 10, posted (12 years 10 months 1 week 2 days 21 hours ago) and read 11493 times:

That's quite a statement 747-438!
The Boeing 727 built Australia's air travel industry, and formed a vital part of TAA/Australian, which ultimately made the airline strong and able to be merged with...Qantas!


User currently offlineNotar520AC From United States of America, joined Jul 2001, 1606 posts, RR: 4
Reply 11, posted (12 years 10 months 1 week 2 days 20 hours ago) and read 11478 times:

Yeah you dolt!


BMW - The Ultimate Driving Machine
User currently offlineQANTAS747-438 From United States of America, joined Jan 2001, 1935 posts, RR: 2
Reply 12, posted (12 years 10 months 1 week 2 days 17 hours ago) and read 11472 times:

AJ---

Well zippidydooda for Australia... I live in Los Angeles so whatever Australia has to thank the 727 for has nothing of concern to me. I just love seeing Qantas cruise into LAX like it owns the place, hence the screen name. And the 727 still sucks.



My posts/replies are strictly my opinion and not that of any company, organization, or Southwest Airlines.
User currently offlineTurtle From United States of America, joined Jan 2001, 206 posts, RR: 0
Reply 13, posted (12 years 10 months 1 week 2 days 5 hours ago) and read 11454 times:

747-438

What are your reasons for saying the 727 sucks? Just curious.


User currently offlineDrgreen757 From United States of America, joined Sep 2001, 155 posts, RR: 0
Reply 14, posted (12 years 10 months 1 week 2 days 4 hours ago) and read 11441 times:

A true aviation fan doesn't think any aircraft sucks. They're all great in their own way.


Save the grey ghosts.
User currently offlineMx727 From Mexico, joined Feb 2001, 122 posts, RR: 0
Reply 15, posted (12 years 10 months 1 week 1 day 13 hours ago) and read 11418 times:

Saab340.
If you have time to come to Mexico City (7341ft. elevation), come by April or May (30 degrees celcius), then you can try to fly MEX-LAX, MEX-PTY, MEX-MXL or some route like that at 2pm full of passengers.
I can assure you that after takeoff you will realise why the 727 needs 3 engines.
Regards.
MX727


User currently offlineRailker From Canada, joined Aug 2006, 171 posts, RR: 0
Reply 16, posted (5 years 10 months 2 days 12 hours ago) and read 11216 times:

I personally love the 727 to death, it's like the American Muscle of the aviation world, as it were. Their engines may not be huge, and performance may not be great at some have said, eats up the entire runway to get off, but I love the look of that plane and most definately the sound of of its engines roaring -- and to think those engines have a hush kit on them, can only imagine how loud they were when the aircraft first came out and didn't have any such hushing. Instead of everything being all quiet and hushed down, when one of these takes off, it's 100% brute power, a rumble you feel in your chest, and if your car's parked on a slope at your favorite observation post near the runway, you'd better hope you have a good strong handbrake.


((That actually happened. My dad's 1992 Ford Thunderbird SC had a weak handbrake. Parked at the emergency entrance gate at the base of runway 25 at YOW, First Air leaving for Iqaluit. Handbrake came loose and the car rolled across the road.))


User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9592 posts, RR: 52
Reply 17, posted (5 years 10 months 2 days 11 hours ago) and read 11195 times:

When the 727 was designed, takeoff performance was very important. In the 50s, a 7,000ft runway was considered long. The days of every airport having 10,000ft runways were far off into the future. Airlines wanted a plane that could operate out of a 5,000ft strip. Engine out performance was a major issue with a twin engine design on such short runways. The 727 was designed to be operated on regional routes and domestic routes where the larger 707 did the transcon and international flights. The 727 had higher capacity than any of the other twin engine planes designed earlier or at similar times like the Caravelle and DC9. They could have made a 727 with two engines, but they would have been pushing the performance capabilities to get over 100 passengers off the ground.

The 727 was influenced heavily by United, American and Eastern. United was the airline pushing for three engines and eventually won. 4 engines were not efficient, and 2 did not offer the required performance. 3 was the design settled on, and it was a runaway success being the first jet to sell over 1,000 airplanes.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineRussianJet From Belgium, joined Jul 2007, 7694 posts, RR: 21
Reply 18, posted (5 years 10 months 2 days 11 hours ago) and read 11189 times:
Support Airliners.net - become a First Class Member!



Quoting AA777-200 (Reply 3):
Why do you ask us these questions. Ask boeing. why did the DC10 have 3 engines?

That's a totally unnecessary thing to say. This is an aviation forum. We all have different interests and depths of knowledge, and we all have different jobs and can all bring different things to the table. Hell, just a wild guess, but I expect there ARE people that work for aircraft manufacturers here. THAT is why we ask questions here. Because the range of people here often leads to a satisfactory answer and an interesting discussion. If he has a civil aviation query, no matter how elementary or pointless it seems to the likes of you, he should ask about it. You do not have to bother yourself answering the question if you are not interested.

Quoting AA777-200 (Reply 3):
Its the design for the plane!!!

Yes, and the reasons it was designed the way it was, for the purposes it was built for, are many and complicated. Basically, he asks why it has or needs three engines. You basically say "because it has". Nice one. Why don't you try talking about the role the plane was intended for, the places it was intended to serve, the aerodynamic issues, the engine technology available at the time, ETOPS issues and so on, and so on, and so on.



✈ Every strike of the hammer is a blow against the enemy. ✈
User currently offlineUnattendedBag From United States of America, joined Oct 2003, 2325 posts, RR: 1
Reply 19, posted (5 years 10 months 2 days 10 hours ago) and read 11134 times:



Quoting SAAB340 (Thread starter):
Can anyone tell me what the third engine purpose is??

It balances the aircraft. This looks kinda odd...


View Large View Medium
Click here for bigger photo!

Photo © Brian Harrison




Slower traffic, keep right
User currently offlineSpeedracer1407 From United States of America, joined Dec 2004, 333 posts, RR: 0
Reply 20, posted (5 years 10 months 2 days 8 hours ago) and read 11052 times:



Quoting RussianJet (Reply 18):
You do not have to bother yourself answering the question if you are not interested.

Well, he's had 7 years to think about it since he posted that response (reply 3). Perhaps he's older and wiser now.



Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
User currently offlineViscount724 From Switzerland, joined Oct 2006, 25117 posts, RR: 22
Reply 21, posted (5 years 10 months 2 days 8 hours ago) and read 11030 times:



Quoting Speedracer1407 (Reply 20):
Well, he's had 7 years to think about it since he posted that response (reply 3). Perhaps he's older and wiser now.



Quoting Railker (Reply 16):
I personally love the 727 to death

Just a sidenote, but when a thread is resurrected after being dormant for years (7 years in this case), it would be courteous to mention this so other users are aware they're replying to an old thread. In this case, the original poster isn't even a valid A.net user ID now.


User currently offlineAirbuster From Netherlands, joined Mar 2007, 442 posts, RR: 0
Reply 22, posted (5 years 10 months 2 days 8 hours ago) and read 11027 times:



Quoting QANTAS747-438 (Reply 9):
727 sucks!

If you can't be constructive to the discussion, why post?

Now, the thing i was wondering was with the engine retrofits available these days for 727's do they also replace the middle engine? As the 2 outer engines would already greatly increase performance, and i suppose cramming a larger engine into the middle S duct would be quite challenging....any info?

rgds

Ab



FLY FOKKER JET LINE!
User currently onlineStarlionblue From Greenland, joined Feb 2004, 17016 posts, RR: 67
Reply 23, posted (5 years 10 months 2 days 5 hours ago) and read 10935 times:



Quoting Drgreen757 (Reply 14):
A true aviation fan doesn't think any aircraft sucks. They're all great in their own way.

All aircraft suck air. That's how turbine engines work.  duck 


To sum up the reasons for the 727 having three engines:
- Engine technology at the time was not quite up to powering a twin of that size.
- Reliability for over water flights. This was way before ETOPS.
- Reliability period. Engines failed more in those days.
- Customer requests.


The third engine, specifically its s-duct, was a bit of development headache for Boeing, but in the end the 727 was a great success for the company.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineBoeing767mech From United States of America, joined Dec 2000, 1025 posts, RR: 3
Reply 24, posted (5 years 10 months 2 days 3 hours ago) and read 10875 times:



Quoting Airbuster (Reply 22):
As the 2 outer engines would already greatly increase performance, and i suppose cramming a larger engine into the middle S duct would be quite challenging....any info?

D Howard did it for UPS on there -100's, they took all three JT8's off and replaced them with Roll-Royce Tays. You can tell the tay airplanes because of the bludge on the #2 inlet, like an DC-10-40 or MD-11.


View Large View Medium
Click here for bigger photo!

Photo © Tim Perkins



David



Never under-estimate the predictably of stupidty
25 Railker : Whoa ... I really have no idea how I managed to get on this thread and think it was current, to tell you the truth. I did not mean, at all, to resurr
26 Max Q : You have to remember, also, the much lower thrust levels of the older JT8D engines on the 727, The -9 was only 14,500 lbs thrust. Thats only 43,500 lb
27 RussianJet : And, not all of us can remember every post from seven years ago, and in the course of seven years many people come and go.
28 Jush : Can I just ask who pulls out a thread from 2001 answers it and then alot of other people talk about a thread which was done almost 7 years ago. And th
29 767nutter : As what everyone else said it needed three, the 727-100 would have been ok with two on light loads but the 727-200 was described as a 'dog' to handle
30 CosmicCruiser : I can't believe I'm responding to such an ignorant post BUT I do want to address the 727 sucks comment. The 727 was/is the DC-3 of the jetage and was
31 Post contains links OldAeroGuy : Quoting SAAB340 (Thread starter): Can anyone tell me what the third engine purpose is?? Without it, the 727 wouldn't have been a copy of the HS Triden
32 LY777 : what an interesting comment! Are you sure you are a true aviation fan?
33 Post contains links and images Viscount724 : The #2 engine intake on the 727-100s with the R-R Tay conversion was also round, not oval like the P&W 727-100. (The 727-200 also has a round #2 inta
34 767nutter : Why? i would have loved to be able to fly that beauty, it didn't have none of this high automation we see nowadays. it cried out to be hand flown in
35 Northwest727 : It was a compromise. In the early 1960s, during the aircraft's birth, UA wanted another 4 engined aircraft to operate out of KDEN. EA wanted a more ef
36 AcNDTTech : Also, back in the mid to late 80's, there was a proposal for a mod to make the 727 a twin by removing the center engine - S-Duct and all. I wish I cou
37 Post contains links and images Starlionblue : This one is bogus I think but it gives an idea of the direction.
38 AcNDTTech : No, not this one. I saw that a while back. The one that I remember was a 200 without the winglets. It may have had UDF engines on it. It may have been
39 Post contains links TSS : You're thinking of the Boeing 7J7, a proposal from the 1980s for a successor to the 727. It looked much like the illustration above, except it featur
40 DocLightning : Except the A320
Top Of Page
Forum Index

Reply To This Topic Why The 3rd 727 Engine
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...
Why No Douglas Competitor To The Boeing 727? posted Mon Jul 31 2006 21:51:50 by 747400sp
Why Is The MD-11 Engine Tipped Up? posted Mon Jun 14 2004 20:31:38 by FrontierCPT
Do You Know Why The 737 Engine Has A Wierd Shape? posted Mon Dec 29 2003 21:53:29 by Captain777
Why The Little Hole At The Bottom Of The Window? posted Tue Oct 17 2006 03:19:07 by Gh123
Why JT8-D For 727 Insteed Of TF30 posted Fri Sep 8 2006 19:35:00 by 747400sp
Beechcraft 1900: Why The T-Tail? posted Fri Aug 4 2006 22:39:24 by KELPkid
Why The Airbus A380 Has Only Two Thrust Reverser? posted Sun Jul 2 2006 14:26:20 by 747400sp
Why The "wheel" On Landing Gear Levers? posted Fri Mar 3 2006 11:52:41 by Slinker
Why The Extra Bogie On DC10-30? posted Thu Jan 5 2006 22:00:40 by SK909
PW4090: Why The Lower Mgtow? posted Tue Nov 15 2005 05:21:43 by Gnomon

Sponsor Message:
Printer friendly format