AA777-200 From United States of America, joined Jul 1999, 323 posts, RR: 2
Reply 3, posted (13 years 8 months 3 weeks 3 days 21 hours ago) and read 12779 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!!!
AJ From Australia, joined Nov 1999, 2403 posts, RR: 24
Reply 5, posted (13 years 8 months 3 weeks 3 days 19 hours ago) and read 12742 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!
Cedarjet From United Kingdom, joined May 1999, 8377 posts, RR: 54
Reply 6, posted (13 years 8 months 3 weeks 3 days 8 hours ago) and read 12695 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
Gregg From United States of America, joined Jun 2000, 327 posts, RR: 0
Reply 7, posted (13 years 8 months 3 weeks 2 days 13 hours ago) and read 12647 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 .....
AJ From Australia, joined Nov 1999, 2403 posts, RR: 24
Reply 10, posted (13 years 8 months 3 weeks 2 days 1 hour ago) and read 12604 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!
QANTAS747-438 From United States of America, joined Jan 2001, 2032 posts, RR: 2
Reply 12, posted (13 years 8 months 3 weeks 1 day 20 hours ago) and read 12583 times:
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.
Mx727 From Mexico, joined Feb 2001, 122 posts, RR: 0
Reply 15, posted (13 years 8 months 3 weeks 16 hours ago) and read 12527 times:
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.
Railker From Canada, joined Aug 2006, 172 posts, RR: 0
Reply 16, posted (6 years 8 months 2 weeks 1 day 15 hours ago) and read 12325 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.))
RoseFlyer From United States of America, joined Feb 2004, 10390 posts, RR: 52
Reply 17, posted (6 years 8 months 2 weeks 1 day 15 hours ago) and read 12304 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!
RussianJet From Belgium, joined Jul 2007, 7771 posts, RR: 21
Reply 18, posted (6 years 8 months 2 weeks 1 day 15 hours ago) and read 12298 times:
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.
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. ✈
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.
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?
Starlionblue From Greenland, joined Feb 2004, 17327 posts, RR: 66
Reply 23, posted (6 years 8 months 2 weeks 1 day 8 hours ago) and read 12044 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.
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."
Boeing767mech From United States of America, joined Dec 2000, 1036 posts, RR: 3
Reply 24, posted (6 years 8 months 2 weeks 1 day 6 hours ago) and read 11984 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.