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Topic: Why Did Boeing Build The 727?
Username: 727LOVER
Posted 2012-04-24 17:45:14 and read 23845 times.

Don't get me wrong, as my username says, I LOOOOOOOOVE the 727. But looking at the 737 fro the rest of our lived thread, and all the gushing over that plane, why didn't Boeing just make a small/mid size two engine, two pilot aircraft for shorter runways in the first place.The 737 has all this longevity because in later years, it filled the 727's role.

Thoughts?






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Topic: RE: Why Did Boeing Build The 727?
Username: tymnbalewne
Posted 2012-04-24 18:19:17 and read 23734 times.

The very short, very inadequate answer is that UA, AA and EA all wanted an airliner to serve smaller cities. UA wanted 4 engines for high altitude airports, AA wanted two engines, and EA wanted three for their overwater flights to the Caribbean, (this was well before ETOPS!).
So, the best compromise was, in fact 3 engines, hence the 727.

Topic: RE: Why Did Boeing Build The 727?
Username: rampart
Posted 2012-04-24 18:50:09 and read 23569 times.

At the time the 727 was conceived, late 1950s, crew of 3 was normal, 3 engines were deemed necessary, and the size of the plane was a step lower than the 707, yet bigger than the DC-9 which was also developing. Only later did Boeing think they needed a smaller jet, which became the 737. They had no intention of growing the 737 to what it is now. Remember, up through the early 1990s, the 727 was the world's best selling airliner, over 1800 built. By that time, the 737 was refreshed and extended, and it took over that role, more than 25 years after it was conceived. The 727 had also planned to refresh and expand, but that became the 757 on the high end, and the 737-300 on the lower end.

-Rampart

Topic: RE: Why Did Boeing Build The 727?
Username: SSTsomeday
Posted 2012-04-24 19:34:42 and read 23365 times.

Quoting rampart (Reply 2):
The 727 had also planned to refresh and expand, but that became the 757 on the high end, and the 737-300 on the lower end.

Yes - And the 727 was not able to evolve the way the 737 could, as in high-bypass turbofan engines, because of the nature of the engine configuration (Fuselage-mounted engines; middle engine intake through the fuselage, etc.)

Incidentally, the 727 was initially designed to replace a number of 4-prop airliners at the time, such as the DC-6/7 I think, and in Canada the Vickers Viscount and Vanguard, etc. 2 Engine technology for airliners was evolving at that time and not common. Engines were not nearly so reliable and therefore safety was more directly dependant on redundancy.

Topic: RE: Why Did Boeing Build The 727?
Username: rampart
Posted 2012-04-24 19:55:20 and read 23280 times.

Quoting SSTsomeday (Reply 3):
Yes - And the 727 was not able to evolve the way the 737 could, as in high-bypass turbofan engines, because of the nature of the engine configuration (Fuselage-mounted engines; middle engine intake through the fuselage, etc.)

There were proposals for a twin 727, minus the middle engine. While I can't recall if these were supposed to be the upcoming higher-bypass CFM engines -- they might have been -- it would have been possible to do that, theoretically. (BAe were planning the same for an extended One-Eleven.) Of course, Lockheed managed a high bypass engine with an S-duct in the tail, but that would have entailed more significant re-engineering on a 727. At any rate, as you say, Boeing realized that it was easier to extend and re-engine the 737 than it was to develop a 727 twin.

-Rampart

Topic: RE: Why Did Boeing Build The 727?
Username: Stitch
Posted 2012-04-24 20:17:00 and read 23129 times.

Quoting rampart (Reply 2):
At the time the 727 was conceived, late 1950s, crew of 3 was normal, 3 engines were deemed necessary, and the size of the plane was a step lower than the 707, yet bigger than the DC-9 which was also developing.
Quoting rampart (Reply 4):
There were proposals for a twin 727, minus the middle engine.

The concept I have seen had the engines below the wing (they look like P&W JT3C turbojets).

Topic: RE: Why Did Boeing Build The 727?
Username: ADent
Posted 2012-04-24 21:01:18 and read 22957 times.

The 727-200 is quite a bit bigger than the 737-200.

So either someone had to create a more powerful engine or you had to go with 3 engines.

No one did the first, so Boeing had to go with the second.

Douglas didn't get a twin engine (DC-9 Super 80) in the same class until 1979.

Topic: RE: Why Did Boeing Build The 727?
Username: frmrCapCadet
Posted 2012-04-24 21:01:18 and read 22953 times.

At the time the 727 was a far more capable plane - range and capacity. The 737 just kept increasing in capability.

Topic: RE: Why Did Boeing Build The 727?
Username: lightsaber
Posted 2012-04-24 21:32:02 and read 22803 times.

For over a decade the 727 was the most produced airliner. I think Boeing made the right market call.   It wasn't until 30 years into 737 production that more of them were produced than the 727! That took a re-engine too! Per Wikipedia's article on the 727, there were 250 of them flying in August 2011. Not bad for a plane with EIS in 1964. Consider that the last 727 was delivered in 1984. The youngest model is 28 years old and yet they're still flying!

Quoting 727LOVER (Thread starter):
why didn't Boeing just make a small/mid size two engine, two pilot aircraft for shorter runways in the first place.

The initial expected market for the 737/DC-9 was pretty small. Not to mention the range expectations. It is ironic that the 727 developed the market to make the 737-200 a success. But even then, the 727-200 out-delivered the 737 in 1978-1980. Much of what we consider the 737 success happened with the 733/734/735 and the engines 25% drop in fuel burn.   

Now some was teething issues. The original 731s had thrust reverser issues. There was also extensive rework done on the flaps. And recall (from Wikipedia):
"In 1970, Boeing received only 37 orders. Facing financial difficulties, Boeing considered closing the 737 production-line and selling the design to Japanese aviation companies."   

The early business case on the 737 wasn't strong. Recall no US airline was a launch customer (a first for Boeing) while Eastern (and others) were strong proponents for the 727. This is a case where the market matured to make the type a success.

Lightsaber

Topic: RE: Why Did Boeing Build The 727?
Username: JoeCanuck
Posted 2012-04-24 21:43:46 and read 22759 times.

They were made because they deserved to be made.

I'll get a fight from the Concorde folk but the 727 is the best looking airliner of all time. I remember flying those into YEV on a regular basis...and how damned loud the things were from the ground. We could hear them clearly from town, a full 8 miles away...and at -40ish, they sounded more like 8 blocks away.

Topic: RE: Why Did Boeing Build The 727?
Username: lasairlinerenth
Posted 2012-04-24 23:00:56 and read 22542 times.

Quoting JoeCanuck (Reply 9):
the 727 is the best looking airliner of all time

I will wholeheartedly second this sentiment. Some forty-odd years ago, I fell in love with the 727 the first time I saw one; since I was only five or six years old at the time, my best guess is it would have been an Eastern Airlines 727 that one of my uncles and his family took from Syracuse, New York to San Antonio, Texas.

I would not get to ride on my first 727 until July 1979, when I flew American Airlines from Ontario, CA to Syracuse, NY and back, with a change of plane in ORD in both directions, of course. I must have been twelve or thirteen at the time and traveling as an unaccompanied minor. LOVED IT!

My last ride on a 727 was a comparatively short United Airlines flight from Denver (DIA) to Ontario in September 1996.

Ah, memories. While I love the 737, the 727 will always have a special place in my heart.

Topic: RE: Why Did Boeing Build The 727?
Username: rampart
Posted 2012-04-25 00:12:25 and read 22373 times.

Quoting Stitch (Reply 5):
The concept I have seen had the engines below the wing (they look like P&W JT3C turbojets).

Yes. If you are thinking of the post-727 redevelopment, with the high bypass engines became the 7N7. I also recall a model (I believe it was in AW&ST) that had the 2 rear-mounted engines, this was mid-70s. Maybe they were low bypass, but I don't think they were late generation (1960s?) turbojets. You might also be thinking of some early models proposed for the first 727, some of which look more like a DC-9, and some which had the T-tail and engines on the wing. There are also early 737 concepts that looked very much like the DC-9. There was a thread on A.net a few months back on the Boeing archive displaying these models, but some of the models are visible here: http://airchive.com/html/museums/boe...g-archives-bellevue-washington-usa

Actually, on that same website I just found a picture of the "727-300" concept with the engines I recall seeing in AW&ST. Rear-mounted, twin, high bypass:
http://airchive.com/html/museums/boe...-300-model-circa-early-1970s/19069
The FLighGlobal archives say that various versions of the 727-300 were offered to UA and BN, who were interested, but then began to favor an all-new airplane, which became the 7N7 (then the 757).

Earlier someone had commented on the difficulty of using high bypass engines in the center-mounted tail. I forgot that the 7X7 had this configuration (as well as the Tristar), a trijet widebody first with a T-tail, then a conventional tail, then late in the design process dropped the 3rd engine to become 767.

-Rampart

Topic: RE: Why Did Boeing Build The 727?
Username: rampart
Posted 2012-04-25 00:34:30 and read 22296 times.

Sorry to add on here, but everyone should find this 1960 article from Flight very interesting! "Boeing's Trimotor: Background to the development of the 727." There are 3-view sillhouetes of various twin-, tri-, and quad-jet concepts of the 727, some with conventional tails, some with t-tails, some with cruciform tails. Also gives the history of the market analysis, and comparisons to the Trident. Within all this concept was also the idea of a smallish jet that was revived to become the 737. But 1960 technology, as we've said, required the 727 first, and it dominated for more than 2 decades.
http://www.flightglobal.com/pdfarchive/view/1960/1960%20-%203094.html

-Rampart

Topic: RE: Why Did Boeing Build The 727?
Username: columba
Posted 2012-04-25 01:37:06 and read 21757 times.

Quoting rampart (Reply 2):
Only later did Boeing think they needed a smaller jet, which became the 737.

Only later Boeing was pushed by LH into developing the 737.


The 727 was the right aircraft back then and a true success, the first jet airliner that had reached the magic number of 1000 aircraft being produced. Not to mention that it is indeed is the most beautiful jetliner ever build.

Topic: RE: Why Did Boeing Build The 727?
Username: AirbusA370
Posted 2012-04-25 01:43:02 and read 21717 times.

And, why didn't the name it this way:

727 -> Two Engines (instead 737)
737 -> Three Engines (instead 727)
747 -> Four Engines (well, correct)

Topic: RE: Why Did Boeing Build The 727?
Username: MD11Engineer
Posted 2012-04-25 01:48:05 and read 21646 times.

Quoting AirbusA370 (Reply 14):
And, why didn't the name it this way:

727 -> Two Engines (instead 737)
737 -> Three Engines (instead 727)
747 -> Four Engines (well, correct)

And the 707 was a glider, right?  

Jan

Topic: RE: Why Did Boeing Build The 727?
Username: ghifty
Posted 2012-04-25 02:39:45 and read 21182 times.

How much commonality is there between the 727 and 737? It's just the same fuselage cross-section and nose, right?

Quoting AirbusA370 (Reply 14):
And, why didn't the name it this way:

727 -> Two Engines (instead 737)
737 -> Three Engines (instead 727)
747 -> Four Engines (well, correct)

Haha, good laugh.

A340 -> 4 engines
A320 -> 2 engines
A330 -> Trijet!
A380 -> 8 engines!
...
A310 -> 1 engine
A300 -> 0?

L-1011..

Quoting lightsaber (Reply 8):
"In 1970, Boeing received only 37 orders. Facing financial difficulties, Boeing considered closing the 737 production-line and selling the design to Japanese aviation companies."

I'm not questioning the legitimacy of that quote, but what's the actual source?.. might lead to more aviation trivia!

Topic: RE: Why Did Boeing Build The 727?
Username: faro
Posted 2012-04-25 03:09:51 and read 20891 times.

Quoting tymnbalewne (Reply 1):
The very short, very inadequate answer is that UA, AA and EA all wanted an airliner to serve smaller cities. UA wanted 4 engines for high altitude airports, AA wanted two engines, and EA wanted three for their overwater flights to the Caribbean, (this was well before ETOPS!).
So, the best compromise was, in fact 3 engines, hence the 727.

Airframe development is often directly tributary of engine development.

A complement to your short answer is that there wasn't at the time an engine capable of powering a 727-like aircraft as a twin, or in any case an engine with low enough fuel burn.


Faro

Topic: RE: Why Did Boeing Build The 727?
Username: BritishB747
Posted 2012-04-25 03:12:25 and read 20858 times.

Was the Boeing B727-100 not very similar to the original proposal for the Hawker Siddeley Trident? Hawker Siddeley even invited Boeing designers over to look at the plans for this amazing new aircraft that they had designed. Then BEA decided to change their requirements and the Trident became another disaster for the British aircraft industry and Boeing unveiled an aircraft more or less identical to the original specification Trident. Amazing the stupidity of HS inviting a rival to look at the plans for their aircraft.

Topic: RE: Why Did Boeing Build The 727?
Username: HAWK21M
Posted 2012-04-25 03:13:04 and read 20855 times.

Quoting MD11Engineer (Reply 15):

 

Nice one.....

aircraft type naming is not so simple & straight  

Although I still wonder why the B717 model name was NOT utilised commercially until much later.

Topic: RE: Why Did Boeing Build The 727?
Username: ebj1248650
Posted 2012-04-25 03:21:20 and read 20750 times.

Quoting rampart (Reply 4):
There were proposals for a twin 727, minus the middle engine.

As I recall, American Airlines was a potential customer for this. The middle engine would have been removed and the middle air intake duct would have been faired over. I don't recall what engines were planned for the fuselage stations.

Topic: RE: Why Did Boeing Build The 727?
Username: columba
Posted 2012-04-25 03:25:27 and read 20705 times.

Quoting HAWK21M (Reply 19):
Although I still wonder why the B717 model name was NOT utilised commercially until much later.

The real 717 is the KC-135, I wonder more about the 720  

Topic: RE: Why Did Boeing Build The 727?
Username: clydenairways
Posted 2012-04-25 03:42:27 and read 20498 times.

As others have pointed out, technology was not available when the 727 was conceived, to make an aircraft of that size and performance with only 2 engines and a 2 man cockpit. And regulations also prohibited it, as engines and systems were much less reliable, and new technologies and automation had to be proven.The success of the 727 paved the way for the 737 to happen.

The 737 came many years later during a time in the late 60's, a time when technology was developing at a rapid rate.
And It was only in the Mid/late '80's thet the later evolutions of the 737 were able to replace the earlier 727's.
The larger 727 models were replaced initially by the 757 and it was not until the 737-800 was developed, that a true 727-200 replacement was built by Boeing.

Also the 727 name could have lived on had the 757 been called the 727-300. Sure the 737 Max will have very little in common with the original 737, so what's in a name really.

Topic: RE: Why Did Boeing Build The 727?
Username: einsteinboricua
Posted 2012-04-25 04:31:47 and read 19859 times.

Quoting AirbusA370 (Reply 14):

And, why didn't the name it this way:

727 -> Two Engines (instead 737)
737 -> Three Engines (instead 727)
747 -> Four Engines (well, correct)

Hahaha good one, but like Airbus, Boeing gives the next designation in line. Since the 727 was the second jet developed (after skipping the 717 reserved for the KC-135), it was given it. Subsequent jets also follow the same pattern.

Topic: RE: Why Did Boeing Build The 727?
Username: warden145
Posted 2012-04-25 04:51:54 and read 19528 times.

Quoting columba (Reply 21):
I wonder more about the 720

Someone who knows for sure will certainly correct me   but IIRC the premise behind that was UA wanting to order a smaller variant of the 707 but not wanting to be seen as ordering 707's (can't remember if that was because they didn't want to get Douglas riled up or if it had something to do with saving face at the BoD meeting), so Boeing changed the model number to secure the order...or something like that   

Topic: RE: Why Did Boeing Build The 727?
Username: crash65
Posted 2012-04-25 05:16:33 and read 19642 times.

I have found the wikipedias of the respective aircraft to be very informative. Give them a try.

http://en.wikipedia.org/wiki/Boeing_727

Topic: RE: Why Did Boeing Build The 727?
Username: mbj2000
Posted 2012-04-25 05:19:35 and read 19657 times.

Quoting BritishB747 (Reply 18):
Was the Boeing B727-100 not very similar to the original proposal for the Hawker Siddeley Trident? Hawker Siddeley even invited Boeing designers over to look at the plans for this amazing new aircraft that they had designed. Then BEA decided to change their requirements and the Trident became another disaster for the British aircraft industry and Boeing unveiled an aircraft more or less identical to the original specification Trident. Amazing the stupidity of HS inviting a rival to look at the plans for their aircraft.

I was asking myself the same question. The Trident was in fact the "original" design... Maybe the british engineers at that time still believed in fairplay in the aircraft business...

Topic: RE: Why Did Boeing Build The 727?
Username: clydenairways
Posted 2012-04-25 05:26:51 and read 19702 times.

Quoting BritishB747 (Reply 18):
Was the Boeing B727-100 not very similar to the original proposal for the Hawker Siddeley Trident? Hawker Siddeley even invited Boeing designers over to look at the plans for this amazing new aircraft that they had designed. Then BEA decided to change their requirements and the Trident became another disaster for the British aircraft industry and Boeing unveiled an aircraft more or less identical to the original specification Trident. Amazing the stupidity of HS inviting a rival to look at the plans for their aircraft.

Well you have to look at this with the perspectine of Post WW2 era and the relationship between the two countries, and there are plenty of other examples of this "one way transfer".

But even saying that, i don't think the final outcome would have been anything different.

Topic: RE: Why Did Boeing Build The 727?
Username: tockeyhockey
Posted 2012-04-25 06:01:18 and read 19027 times.

what was the relationship, if any, between the 727 and the caravelle?

Topic: RE: Why Did Boeing Build The 727?
Username: clydenairways
Posted 2012-04-25 06:14:02 and read 18757 times.

Quoting tockeyhockey (Reply 28):
what was the relationship, if any, between the 727 and the caravelle?

Douglas considered teaming up with SUD Aviation to build the caravelle with GE angines but they went with the DC9 in the end.

Topic: RE: Why Did Boeing Build The 727?
Username: railker
Posted 2012-04-25 06:39:10 and read 18296 times.

Quoting einsteinboricua (Reply 23):
Hahaha good one, but like Airbus, Boeing gives the next designation in line. Since the 727 was the second jet developed (after skipping the 717 reserved for the KC-135), it was given it. Subsequent jets also follow the same pattern.

Indeed, otherwise the B-52 would've had the Boeing 787 title a long time ago, assuming the military planes are allowed in the sandbox.

Topic: RE: Why Did Boeing Build The 727?
Username: SP90
Posted 2012-04-25 07:16:04 and read 17573 times.

Why was the KC-135 given the 717 designation? Everything I could find on the 717 points to the re-badged MD-95. Was it Boeing policy at the time to just give it the next number on the list or was this a special case since its a military design based on the civilian 707? Was it just an internal naming for housekeeping purposes I mean they had to call it something during development I suppose.

Topic: RE: Why Did Boeing Build The 727?
Username: JAAlbert
Posted 2012-04-25 07:18:54 and read 17581 times.

Quoting JoeCanuck (Reply 9):
remember flying those into YEV on a regular basis...and how damned loud the things were from the ground.

Remember when Eastern Airlines referred to its 727s as "Whisper Jets"? That always cracked me up.

I agree the 727's shape is iconic. It screams 60's style.

Topic: RE: Why Did Boeing Build The 727?
Username: PHLBOS
Posted 2012-04-25 07:39:03 and read 17154 times.

Quoting ADent (Reply 6):
The 727-200 is quite a bit bigger than the 737-200.

True, but one thing to keep in mind is that the entire 727 family included the original and shorter 727-100 series as well, which rolled out about 3 years earlier than its larger -200 cousin.

Quoting rampart (Reply 2):
Remember, up through the early 1990s, the 727 was the world's best selling airliner, over 1800 built.

I'm assuming that number includes all 727 variants (-100 & -200).

Topic: RE: Why Did Boeing Build The 727?
Username: lightsaber
Posted 2012-04-25 07:43:23 and read 17081 times.

Quoting ghifty (Reply 16):
I'm not questioning the legitimacy of that quote, but what's the actual source?.. might lead to more aviation trivia!

Pulled from the wikipedia Boeing 737 page, but this was the ultimate source:
http://www.seattlepi.com/default/art...livers-its-5-000th-737-1195654.php

Pratt ditched the JT10D as 737 sales were too poor to justify further investment and instead focused on the PW2000 for the 757. Oops.

Lightsaber

Topic: RE: Why Did Boeing Build The 727?
Username: YULWinterSkies
Posted 2012-04-25 08:24:02 and read 16267 times.

Quoting 727LOVER (Thread starter):
But looking at the 737 fro the rest of our lived thread, and all the gushing over that plane, why didn't Boeing just make a small/mid size two engine, two pilot aircraft for shorter runways in the first place.

As others have said, technology was not yet available. Airbus faced that exact same problem in the late 80's while developing the A330 and A340. Now, the same fate as the 727 happens to the A340 which is outsold and outperformed on 90% of its missions by the A330. To paraphrase you, don't get me wrong, i LOOOOOVE the A340. But technology evolves and that is fine.

Topic: RE: Why Did Boeing Build The 727?
Username: CALTECH
Posted 2012-04-25 08:49:42 and read 15830 times.

Always liked this version,.....

Topic: RE: Why Did Boeing Build The 727?
Username: Tan Flyr
Posted 2012-04-25 08:53:09 and read 15712 times.

Quoting JAAlbert (Reply 32):
Remember when Eastern Airlines referred to its 727s as "Whisper Jets"? That always cracked me up.

Well compared to the B720's or the early DC-8's, they were slightly more quiet.

Unless I have missed it..no one mentioned the other reason for the 727..IIRC both UA/EA both told boeing they needed a jet that could take off from LGA fully loaded and make a 2 hour trip.(or something close to that) AA also reiterated this requirment. So the 727-100 originally had to meet the LGA (and later DCA) runway length issues. Also, carriers wanted to bring jet service to more medium or medium/large cites and routes from them for competititve reasons.

The DC-9 -10 series enabled carries such as EA/ TW/ OZ /NC to bring even more jet service to smaller communities.

When the 72S came along in 1967 (lead sleds!!) I believe they were weight restricted on very hot days at airports of any significant elevation or runway length issues. The 72A with higher thrust Pratts solved that issue in 71 or 72 as I recall.

The reduced weight of the 737 made it competitieve to the DC9-30 and soon after UA saw the success LH was having, jumped on board with a 60 frame order.

Hope my 2 cents worth here helps fill in a few blanks.

Topic: RE: Why Did Boeing Build The 727?
Username: BoeingGuy
Posted 2012-04-25 08:55:38 and read 15663 times.

Quoting AirbusA370 (Reply 14):
And, why didn't the name it this way:

727 -> Two Engines (instead 737)
737 -> Three Engines (instead 727)
747 -> Four Engines (well, correct)

As other posters have indicated, Boeing went in order of development. The 707 came first. The 787 is the most recent. It remains to be seen what the 797 will be, or what any subsequent new models will be designated (808?).

Quoting SP90 (Reply 31):
Why was the KC-135 given the 717 designation? Everything I could find on the 717 points to the re-badged MD-95. Was it Boeing policy at the time to just give it the next number on the list or was this a special case since its a military design based on the civilian 707? Was it just an internal naming for housekeeping purposes I mean they had to call it something during development I suppose.

The KC-135 was intended to be designated the 717, but that never officially caught on. Thus, when Boeing bought out McDD and at first intended to keep the MD-95 in production, they wanted to rename it into a Boeing model series. 717 was still available. The MD-80/90/11 were not kept in production for very long so were never renamed to a Boeing-heritage model number.

Quoting JAAlbert (Reply 32):
Remember when Eastern Airlines referred to its 727s as "Whisper Jets"? That always cracked me up.

They were quiet compared to turbojet 707s are DC-8s. In today's world when we have airplanes like the 787, Whisper Jet may seem comical for the 727. But compared to older jets, it was relatively quiet.

Topic: RE: Why Did Boeing Build The 727?
Username: 135mech
Posted 2012-04-25 09:02:25 and read 15478 times.

Quoting SP90 (Reply 31):
Why was the KC-135 given the 717 designation? Everything I could find on the 717 points to the re-badged MD-95. Was it Boeing policy at the time to just give it the next number on the list or was this a special case since its a military design based on the civilian 707? Was it just an internal naming for housekeeping purposes I mean they had to call it something during development I suppose.

I have books about the 707's and the KC-135's, when the numbering of the 720 was taking place... there was actually a "paranoia" or "superstition" about the number 717 and the number being a "teen", so that is why the airlines went with the 720. It was not a new 7 series, just a modified 707, that is why it did not get the 727 numbering at the time. The military did not care or have concern of the superstitions of the "teen" and as seen today the KC-135 is still going strong!

Also, the KC-135 was not a variant of the civlian 707 but was a variation of the original 367-80; it's thoroughly a whole different airlplane and entered service prior to the 707. It's fuselage width and length, wings, landing gear, flaps, leading edge flaps, and even the hydraulic systems are different. However to save $, Boeing did keep the empenage/tail and the cockpit similar for production costs and the Air Force is using old 707's as spares for these parts at the Davis-Monthan AFB boneyard.

When Boeing bought out MDC in 1995, the MD-95 (DC-9-95) was being introduced at that time, and so Boeing put thier label on it and called the 717-200 (not the one hundred since that was already taken). By this time, airlines did not worry about those long overdue superstitions in the "teen" numbering.

Topic: RE: Why Did Boeing Build The 727?
Username: BoeingGuy
Posted 2012-04-25 09:24:16 and read 15054 times.

Quoting 135mech (Reply 39):
I have books about the 707's and the KC-135's, when the numbering of the 720 was taking place... there was actually a "paranoia" or "superstition" about the number 717 and the number being a "teen", so that is why the airlines went with the 720.

Not correct. The 720 was named due to a political issue with UA. UA choose the DC-8 over the 707 originally for its longer haul routes. Then Boeing introduced the shorter haul 707-020. UA wanted it for shorter routes like SEA-SFO and SFO-DEN. However, UA didn't want to go to their Board of Directors requesting now to purchase 707s, after already selecting the DC-8. They didn't want to appear that they made a mistake or slap Douglas in the face (UA intended the DC-8s and 707-020s to serve different missions).

UA told Boeing that if they called the 707-020 the "720" and make it sound like an all new airplane, they'd buy some. Thus the 720 was born.

Topic: RE: Why Did Boeing Build The 727?
Username: RKSofACinUSA
Posted 2012-04-25 09:31:24 and read 14896 times.

Though I understand and respect the place that the 727 held in aviation history, I don't have too many fond memories of it. The memories that sticks with me are sitting in the back of a loaded 727-200 on hot summer days in Tampa wondering if that back heavy plane was ever going to lift off the 10,000 ft. runway. Many times I held my breath going over Hillsborough Avenue at a very low altitude saying to myself "lift baby lift!".

Topic: RE: Why Did Boeing Build The 727?
Username: 135mech
Posted 2012-04-25 09:37:12 and read 14770 times.

Quoting BoeingGuy (Reply 40):
Not correct. The 720 was named due to a political issue with UA. UA choose the DC-8 over the 707 originally for its longer haul routes. Then Boeing introduced the shorter haul 707-020. UA wanted it for shorter routes like SEA-SFO and SFO-DEN. However, UA didn't want to go to their Board of Directors requesting now to purchase 707s, after already selecting the DC-8. They didn't want to appear that they made a mistake or slap Douglas in the face (UA intended the DC-8s and 707-020s to serve different missions).

UA told Boeing that if they called the 707-020 the "720" and make it sound like an all new airplane, they'd buy some. Thus the 720 was born.

Cool for the update, however there WAS a superstition of a "teen" number written in the books you can buy on the 707's.

Topic: RE: Why Did Boeing Build The 727?
Username: connies4ever
Posted 2012-04-25 09:45:51 and read 14568 times.

Quoting SSTsomeday (Reply 3):
Incidentally, the 727 was initially designed to replace a number of 4-prop airliners at the time, such as the DC-6/7 I think, and in Canada the Vickers Viscount and Vanguard, etc. 2 Engine technology for airliners was evolving at that time and not common. Engines were not nearly so reliable and therefore safety was more directly dependant on redundancy.

The Viscount replacement (for AC anyway) was the outcome of an evaluation of the DC-9-10 (initially), the BAC 1-11, and (briefly) the Sud Caravelle (probably the Srs 10). Sud tried to sweeten the deal by offering license production at Canadair in Montreal, but really, by late 1960s it was a comparative dog. The 1-11, while a nice niche a/c was a) too small, and b) too short-legged for AC's liking. Woefully underpowered as well.

Quoting rampart (Reply 4):
Of course, Lockheed managed a high bypass engine with an S-duct in the tail, but that would have entailed more significant re-engineering on a 727. A

An interesting thing to keep in mind with centre-line engined a/c is the middle engine performance penalty where the engine is buried in the fuse (unlike the DC-10/MD-11). Going through an S-duct like on the 727 & L-1011 results in a flow velocity reduction that amounts to, depending on the design, an 18-20% mass flow reduction and consequent loss of thrust. One of the reasons you don't see this sort of design anymore -- also the fact the high BP engines have just gotten so much bigger and more reliable.

Quoting BritishB747 (Reply 18):
Was the Boeing B727-100 not very similar to the original proposal for the Hawker Siddeley Trident? Hawker Siddeley even invited Boeing designers over to look at the plans for this amazing new aircraft that they had designed. Then BEA decided to change their requirements and the Trident became another disaster for the British aircraft industry and Boeing unveiled an aircraft more or less identical to the original specification Trident. Amazing the stupidity of HS inviting a rival to look at the plans for their aircraft.

BEA I believe wanted something 727-sized initially, but as you indicated revised the requirements to make the a/c "tuned" for European routes. Which resulted in HS producing a niche a/c that very few other airlines actually wanted. Actually, if BEA had had their way I think they would simply have purchased the 727-100.

Quoting columba (Reply 21):
The real 717 is the KC-135, I wonder more about the 720

I can't remember the name, but the chairman of UA at the time was bound and determined that UA would not be seen to be ordering 707s of any series after purchasing 40 DC-8s. So, the 707-020 (as it was then known) became the 720. Possibly justified since the wing is different and the fuse is I think about 13 ft shorter.

Quoting BoeingGuy (Reply 38):
The KC-135 was intended to be designated the 717, but that never officially caught on.
Quoting 135mech (Reply 39):
I have books about the 707's and the KC-135's, when the numbering of the 720 was taking place... there was actually a "paranoia" or "superstition" about the number 717 and the number being a "teen", so that is why the airlines went with the 720.

Actually it is a 717. IIRC in the entrance area it states Boeing Model 717 on every C-135, whatever variant. This is likely a reference to the design study.

Topic: RE: Why Did Boeing Build The 727?
Username: BoeingGuy
Posted 2012-04-25 09:50:10 and read 14441 times.

Quoting 135mech (Reply 42):
Cool for the update, however there WAS a superstition of a "teen" number written in the books you can buy on the 707's.

Not that I'm aware of, but I'll look into it. I thought 717 just never caught on as an inform KC-135 designation. Interesting question. What books have you looked at?

Topic: RE: Why Did Boeing Build The 727?
Username: FX1816
Posted 2012-04-25 09:53:27 and read 14393 times.

Quoting 135mech (Reply 39):
When Boeing bought out MDC in 1995, the MD-95 (DC-9-95) was being introduced at that time

Actually I believe it was 1997. I also believe that the MD-95 was not actually a DC-9-95. That ended with the MD-87 or MD-88.

FX1816

Topic: RE: Why Did Boeing Build The 727?
Username: BoeingGuy
Posted 2012-04-25 09:59:59 and read 14272 times.

Quoting FX1816 (Reply 45):
Actually I believe it was 1997. I also believe that the MD-95 was not actually a DC-9-95. That ended with the MD-87 or MD-88.

Yeah, someone posted that recently in a different thread. I think they were type certified as DC-9-82 and DC-9-83, but the MD-87 and MD-88 were type certified as the MD-xx. What I didn't know was that the 720 was type certified as the 720, not 707-020 as I had believed.

Topic: RE: Why Did Boeing Build The 727?
Username: Stitch
Posted 2012-04-25 10:01:04 and read 14277 times.

Quoting BoeingGuy (Reply 44):
I thought 717 just never caught on as an inform KC-135 designation.

Boeing Historian Mike Lombardi confirmed in an interview with James Wallace in The Seattle Post-Intelligencer that 717-100 was Boeing's internal designation for the KC-135, hence when the MD-95 was renamed, it became the 717-200 and the proposed stretch was the 717-300.

http://www.seattlepi.com/business/ar...rphan-717-isn-t-out-of-1162508.php

Topic: RE: Why Did Boeing Build The 727?
Username: FlyPIJets
Posted 2012-04-25 10:22:17 and read 13814 times.

Quoting 727LOVER (Thread starter):
why didn't Boeing just make a small/mid size two engine, two pilot aircraft for shorter runways in the first place.

Wasn't the proposal for the 727 two pilot at first. Then it was made into a three manned flight deck at the request of UA to avoid a perceived labor dispute?

Topic: RE: Why Did Boeing Build The 727?
Username: daviation
Posted 2012-04-25 10:30:08 and read 13633 times.

This is a really interesting discussion. Learn something new every day.

I flew on many 727s - American, Eastern, National.

If I can add anything to this topic, most 757 trainers and pilots did not consider the plane a bigger, newer 727. They took great pains in AWST articles to point out that the 757 was a completely different species, handled differently, had completely different avionics, and basically had no relation to the 727 whatsoever.

As for the 727's noise footprint, we had family that lived in Lawrence, Long Island, right under the JFK approach. OMG! The 727s were loud, but the 707s and DC-8s were beyond belief. The 727 wasn't exactly a "whisper jet," but it was substantially less noisy than the 707/DC-8.

I was even in a landing go-around at LGA because our 727 floated too long over runway 31. And I was a passenger on two different 727 engine-compressor stalls during takeoff. I may be wrong on this, but I heard that the middle-engine had a propensity for cross-wind compressor stalls. That's what our pilot said, anyway.

Topic: RE: Why Did Boeing Build The 727?
Username: ckfred
Posted 2012-04-25 10:30:11 and read 13667 times.

When the 727 came out, it was designed for several roles.

1. Fly at times when a 707 or DC-8 was too large.
2. Fly into airports that couldn't handle a 707 or DC-8, such as DCA.
3. Fly the short and medium haul routes.

The 737 was meant to fly routes that were being flown by planes raning from the CV-240 to the DC-3. With the plane sitting so low to the ground, servicing a 737 was easier than a 727. Despite the fact that the 727 had a built-in rear staircase, it still needed portable stairs to use L1. A 737 had folding stairs under L1, so it could go into any airport that had sufficient runway length.

Also, the original 737 usually flew shorter routes than the 727, or on flights for which the 727 had too many seats.

If I remember correctly, AA had their 727-100s configured for 22 in first and 66 in coach. So, think how few seats a 737-200 had back in the 60s and early 70s. They were the regional jets for the days of regulation.

The only reason that the 737NG can fly trans-con routes is that Boeing was losing sales to the A320 family. Losing a major order to United, a longtime customer, got Boeing to update the 737 with the mantra, "faster, higher, farther."

Topic: RE: Why Did Boeing Build The 727?
Username: N1120A
Posted 2012-04-25 10:30:21 and read 13646 times.

Quoting 727LOVER (Thread starter):
why didn't Boeing just make a small/mid size two engine, two pilot aircraft for shorter runways in the first place

Different technology and requirements of the day. The 727 was, in large part, designed for United's Denver hub and Eastern's over-water requirements. Also remember that, at most US airlines, the 737 had to operate with 3 pilots for a time, because of union rules.

Quoting BritishB747 (Reply 18):
Was the Boeing B727-100 not very similar to the original proposal for the Hawker Siddeley Trident?

Well, the Trident had horrid performance compared to the 727.

Topic: RE: Why Did Boeing Build The 727?
Username: 135mech
Posted 2012-04-25 10:59:03 and read 13014 times.

Quoting BoeingGuy (Reply 44):

Not that I'm aware of, but I'll look into it. I thought 717 just never caught on as an inform KC-135 designation. Interesting question. What books have you looked at?

@ BoeingGuy, Here's one of the books that mentions it...and thanks for your additional information!

707


Here's from Boeing's website about the 720:
http://www.boeing.com/commercial/707family/720.html

{Initially the plane was identified as the 707-020, was later changed to 717-020 and, with input from launch customer United Airlines, was eventually designated the 720. Outwardly the model 720 resembled the 707, but it was a very different airplane.}


Quoting connies4ever (Reply 43):
Actually it is a 717. IIRC in the entrance area it states Boeing Model 717 on every C-135, whatever variant. This is likely a reference to the design study.

Yes, it is a as Stitch says, it is a Boeing 717 and has many variants, the KC-135 Tanker is 717-148 as indicated on it's identiplate in the crew entry chute.

Quoting Stitch (Reply 47):
Boeing Historian Mike Lombardi confirmed in an interview with James Wallace in The Seattle Post-Intelligencer that 717-100 was Boeing's internal designation for the KC-135

Precisely, thanks for that input Stitch!

Topic: RE: Why Did Boeing Build The 727?
Username: connies4ever
Posted 2012-04-25 11:04:56 and read 12906 times.

Quoting daviation (Reply 49):
I may be wrong on this, but I heard that the middle-engine had a propensity for cross-wind compressor stalls

Per my Reply 43, a significant cross-wind and the middle engine S-duct would result in a very large loss of mass flow through the compressor, so, yes, to me a compressor stall is quite possible.

Topic: RE: Why Did Boeing Build The 727?
Username: BoeingGuy
Posted 2012-04-25 11:12:42 and read 12753 times.

Quoting 135mech (Reply 52):
Outwardly the model 720 resembled the 707, but it was a very different airplane.}

I think this is an exaggeration. The 720 was slightly smaller; had thinner structure in some places for weight reduction; but was a 707 inside and out. I wouldn't call it a very different airplane.

If it looks like a duck and quacks like a duck, then it's a duck. The books I've read say that for all intents and purposes, a 720 is/was a 707.

Topic: RE: Why Did Boeing Build The 727?
Username: vc10
Posted 2012-04-25 11:17:31 and read 12663 times.

Quoting N1120A (Reply 51):
Different technology and requirements of the day. The 727 was, in large part, designed for United's Denver hub and Eastern's over-water requirements. Also remember that, at most US airlines, the 737 had to operate with 3 pilots for a time, because of union rules.



I think you will find that in the USA at the time of initial design/ construction of the B727 a federal requirement was that any multi engine aircraft above a certain weight had to carry a Flight Engineer and that is why the 727 minimum crew was 2 pilots and a F/E . Now the pilot union in tthe USA with many airlines insisted that all that airlines F/E had to have previous pilot qualifications as well as a F/E 's ticket. Anybody remember all those flight training schools who made money from training pilots to get a B727 F/E rating.

At some time in the 1970s I believe this ruling was relaxed and we entered the era of the 2 pilot crews no matter how big or small the aircraft was

Topic: RE: Why Did Boeing Build The 727?
Username: 135mech
Posted 2012-04-25 11:23:48 and read 12580 times.

Quoting BoeingGuy (Reply 54):
I think this is an exaggeration. The 720 was slightly smaller; had thinner structure in some places for weight reduction; but was a 707 inside and out. I wouldn't call it a very different airplane.

If it looks like a duck and quacks like a duck, then it's a duck. The books I've read say that for all intents and purposes, a 720 is/was a 707.

It was a quote right off of the Boeing website, so their words directly. Also, if you look at the nose gear doors, the configuration of the 720 nose looks a lot like a KC-135's with the follow up door behind the gear instead of the two beside it.  

[Edited 2012-04-25 11:35:08]

Topic: RE: Why Did Boeing Build The 727?
Username: asteriskceo
Posted 2012-04-25 11:39:52 and read 12268 times.

Quoting SSTsomeday (Reply 3):
Yes - And the 727 was not able to evolve the way the 737 could, as in high-bypass turbofan engines, because of the nature of the engine configuration (Fuselage-mounted engines; middle engine intake through the fuselage, etc.)

I have a question about the middle engine, and I suppose that this also applies to the L-1011. As the aircraft ages, does the nature of the intake's position within the fuselage pose any sort of safety risk? I have always wondered this.

Topic: RE: Why Did Boeing Build The 727?
Username: crash65
Posted 2012-04-25 11:41:59 and read 12269 times.

Quoting FlyPIJets (Reply 48):
Wasn't the proposal for the 727 two pilot at first. Then it was made into a three manned flight deck at the request of UA to avoid a perceived labor dispute?

Not true at all. Having flown "the panel" in the 727-200 I can assure you, the technology wasn't mature enough to automate the systems. As a 727 flight engineer I was VERY busy during and after engine starts, paralleling generators and getting them on the bus (9 amber lights and nine switches plus a phase knob on that panel). Compared to a New-Gen 737, one switch for each generator and they parallel themselves, other aircraft you don't even need a switch, they sense the start sequence as complete, and the generators automatically come on line. The real proof that the engineer was needed was during two-engine-inoperative approaches. After making sure the essential electrical bus was covered and doing the major electrical down load flow (pulling those lavatory drain heater circuit breakers was a real finger strength test), you had to drop to your knees with the gear crank handle to manually release the gear up locks, then crank the landing gear in place, individually.

Good times!!!  

Topic: RE: Why Did Boeing Build The 727?
Username: 135mech
Posted 2012-04-25 11:47:54 and read 12131 times.

I saw this beauty last week in San Antonio at Kelly. She is a beauty!


View Large View Medium
Click here for bigger photo!

Photo © Dennis Muller - Aerospray



Mod edit: Please use the thumbnail code to post images from the database.

[Edited 2012-04-27 10:28:52 by srbmod]

Topic: RE: Why Did Boeing Build The 727?
Username: bohica
Posted 2012-04-25 11:51:14 and read 12067 times.

Quoting connies4ever (Reply 43):
BEA I believe wanted something 727-sized initially,

BEA was unhappy with their Tridents and actually wanted to buy the 727-200. The British government, who owned BEA at the time told BEA they had to "Buy British." BEA ended up with the Trident Three with a booster engine installed above engine #2 in the tail.

Quoting ckfred (Reply 50):
If I remember correctly, AA had their 727-100s configured for 22 in first and 66 in coach. So, think how few seats a 737-200 had back in the 60s and early 70s.

IIRC 737's were all Y before the 1980's, so their seating capacity was close to a 721. I never saw an F cabin in a 737 until the early-mud 80's.

Topic: RE: Why Did Boeing Build The 727?
Username: crash65
Posted 2012-04-25 11:53:54 and read 12059 times.

There it is in all her glory!!!



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Click here for bigger photo!

Photo © Haydn Pound

Topic: RE: Why Did Boeing Build The 727?
Username: FlyMKG
Posted 2012-04-25 12:04:51 and read 11801 times.

Quoting ckfred (Reply 50):
Despite the fact that the 727 had a built-in rear staircase, it still needed portable stairs to use L1. A 737 had folding stairs under L1, so it could go into any airport that had sufficient runway length.

Some early 727s had folding stairs under the L1 door as well. My company used to have a former Eastern 722 that had a panel under the L1 door where the stairs used to be.

FlyMKG

Topic: RE: Why Did Boeing Build The 727?
Username: Max Q
Posted 2012-04-25 12:28:04 and read 11408 times.

Quoting crash65 (Reply 58):

Not true at all. Having flown "the panel" in the 727-200 I can assure you, the technology wasn't mature enough to automate the systems. As a 727 flight engineer I was VERY busy during and after engine starts, paralleling generators and getting them on the bus (9 amber lights and nine switches plus a phase knob on that panel). Compared to a New-Gen 737, one switch for each generator and they parallel themselves, other aircraft you don't even need a switch, they sense the start sequence as complete, and the generators automatically come on line. The real proof that the engineer was needed was during two-engine-inoperative approaches. After making sure the essential electrical bus was covered and doing the major electrical down load flow (pulling those lavatory drain heater circuit breakers was a real finger strength test), you had to drop to your knees with the gear crank handle to manually release the gear up locks, then crank the landing gear in place, individually.

You have a good point. I spent four years as a B727FE as well and, as you say it was as far from automated as you could get, with perhaps the exception of the pressurisation panel on the -200 which was pretty much set and forget.


However I disagree that technology was not sufficiently advance to have automated the systems if Boeing really wanted to. Keep in mind that the technology existed at the time for the incredible XB70 to fly with only two Pilots (no flight engineer) and the first flight of the 727 was only a year before the Valkyrie.



I do think it was more of a Union issue.

Topic: RE: Why Did Boeing Build The 727?
Username: Dreadnought
Posted 2012-04-25 12:32:05 and read 11347 times.

Quoting 135mech (Reply 42):
Cool for the update, however there WAS a superstition of a "teen" number written in the books you can buy on the 707's.

According to this Boeing article, 717 was the original designation of the KC135.

Quote:
The Dash 80 led to two airplanes: The 707, the world’s first successful commercial jet; and the Model 717, the world’s first production jet tanker—better known as the KC-135
http://www.boeing.com/news/frontiers/archive/2006/july/i_history.pdf

Topic: RE: Why Did Boeing Build The 727?
Username: 135mech
Posted 2012-04-25 12:38:44 and read 11267 times.

Quoting Dreadnought (Reply 64):
According to this Boeing article, 717 was the original designation of the KC135.

Copy, as I later stated/confirmed. Worked them for 21 wonderful years.  

This sums it up well and gives way to the 727:
http://www.boeing.com/commercial/707family/720.html

"As the 707-100 was being introduced and the long-range 707-300 was being planned, Boeing also decided to develop a 707 derivative with increased performance for short-to-medium range routes, allowing the plane to operate from shorter runways.

Initially the plane was identified as the 707-020, was later changed to 717-020 and, with input from launch customer United Airlines, was eventually designated the 720.

Outwardly the model 720 resembled the 707, but it was a very different airplane.

It had a much lighter structure and was 9 feet (2.74 meters) shorter than the 707-100. It also had an increased wing sweep on the leading edge between the fuselage and inboard engines as well as full-span Krueger leading edge flaps.

The 720 carried less fuel than the 707-100. Combined with its lighter structure, this gave the plane a lower gross weight, increased takeoff performance and a higher top speed.

The 720 went into service on July 5, 1960 with United Airlines. Boeing built 65 model 720s.

The only variant of the 720 was the 720B which first flew on October 6, 1960.

The main difference on the 720B was the installation of Pratt and Whitney JT3D Turbofan engines that increased the takeoff and climb performance as well as cruise speed of the plane.

Boeing built a total of 89 720Bs.

The 720 proved to be an economical plane to operate and was a favorite of pilots, passengers and operators alike.

The rapid pace of technology soon caught up with it as the more capable 727 replaced the 720 as the leader in the medium-range, high-performance market."

This is directly from Boeing's webpages.

[Edited 2012-04-25 13:01:27]

http://www.boeing.com/commercial/707family/deriv.html

"DerivativesAnother aircraft type that traces its ancestry to the 707 prototype is the U.S. Air Force KC/C-135 tanker-transport/cargo airplane. Boeing built 820 of these aircraft for the Strategic Air Command and the Military Air Transport Service (predecessor of the Military Airlift Command). The KC/C-135 series was initially designated within The Boeing Company as the model 717. In January 1998, the 717 model number was reassigned to the commercial line for the 717-200 regional jetliner.

Additionally, three 707-120s plus two 707-320Bs, designated VC-137s, were delivered to the Military Airlift Command for transporting high government officials. These 707s transported the President for more than 30 years until replaced in 1990 by two 747-200s designated as VC-25s.

Recent military applications of the 707 are the E-3 Airborne Warning and Control System or AWACS (used by the U.S. Air Force, NATO, the Saudi government and the French and British air forces for airborne surveillance, command and control) and the E-6 used by the U.S. Navy for submarine communications.

When the 707 production line was closed at the end of May 1991, Boeing had sold 1,010 of all types (not counting the KC-135 series). "

 Big grin


[Edited 2012-04-25 13:04:28]

Topic: RE: Why Did Boeing Build The 727?
Username: connies4ever
Posted 2012-04-25 13:13:54 and read 10692 times.

Quoting BoeingGuy (Reply 54):
I think this is an exaggeration. The 720 was slightly smaller; had thinner structure in some places for weight reduction; but was a 707 inside and out. I wouldn't call it a very different airplane.
Quoting 135mech (Reply 65):
It had a much lighter structure and was 9 feet (2.74 meters) shorter than the 707-100. It also had an increased wing sweep on the leading edge between the fuselage and inboard engines as well as full-span Krueger leading edge flaps.

As 135mech says, a very different airplane meant for a different mission. The increased sweep section on the inboard section of the wing IIRC was usually called "the glove". And the full span Krueger flaps really boosted t/op performance.

Length would have been comparable to the Qantas Model -138s meant for long over-water Pacific missions.

Due to the shorter moment arm, was the fin height raised somewhat ? Never read anything about that.

Topic: RE: Why Did Boeing Build The 727?
Username: BoeingGuy
Posted 2012-04-25 13:20:25 and read 10554 times.

Quoting connies4ever (Reply 66):
Due to the shorter moment arm, was the fin height raised somewhat ? Never read anything about that.

They ended up making a modification to UA's original 720s to increase tail height. Not sure of all the history of that. I had read once that the 707-120 at least was a bit less stable to fly than the -320 due to its shorter fuselage. Not sure if the similar sized 720 had the same problem or if the wing and tail changes made it a bit more stable.

Everything you ever wanted to know about the 720 can be found in this outstanding book (I have the entire series of these books, and all are great):

http://www.amazon.com/Boeing-Great-A...892437031/ref=cm_cr_pr_product_top

Topic: RE: Why Did Boeing Build The 727?
Username: boeingmd82
Posted 2012-04-25 13:30:04 and read 10395 times.

The 727 was also the first jetliner to feature a gas turbine auxiliary power unit. If I remember correctly it was installed in the center of the fuselage below deck and vented out through the starboard wing tip. I remember sitting on the ground in an American 727-200 and feeling the thing vibrate under my feet when I was a kid.

Topic: RE: Why Did Boeing Build The 727?
Username: CargoIT
Posted 2012-04-25 13:44:56 and read 10144 times.

Quoting ghifty (Reply 16):
[
[quote=ghifty,reply=16]L-1011..
Quoting ghifty (Reply 16):
A340 -> 4 engines
A320 -> 2 engines
A330 -> Trijet!
A380 -> 8 engines!
...
A310 -> 1 engine
A300 -> 0?

L-1011..

1011 is a binary number. 11 binary is 3 decimal!

Topic: RE: Why Did Boeing Build The 727?
Username: connies4ever
Posted 2012-04-25 14:54:30 and read 9184 times.

Quoting BoeingGuy (Reply 67):
I had read once that the 707-120 at least was a bit less stable to fly than the -320 due to its shorter fuselage.

Probably related to a shorter moment arm and reduced rudder effectiveness. Qantas model -138s and the 720 would have the same issue.

Topic: RE: Why Did Boeing Build The 727?
Username: timz
Posted 2012-04-25 16:05:11 and read 8248 times.

Quoting boeingmd82 (Reply 68):
If I remember correctly it [the APU] was installed in the center of the fuselage below deck and vented out through the starboard wing tip.

The exhaust was on top of the wing near the root.

Topic: RE: Why Did Boeing Build The 727?
Username: s4popo
Posted 2012-04-25 16:23:18 and read 8020 times.

I saw this on eBay today, and I immediately thought of this topic.


http://www.ebay.com/itm/190670536512...MEWAX:IT&_trksid=p3984.m1423.l2649


It definitely shows how much bigger the 727 is vs. the older 737s.

Topic: RE: Why Did Boeing Build The 727?
Username: SEPilot
Posted 2012-04-25 16:34:38 and read 7884 times.

Quoting SSTsomeday (Reply 3):
Engines were not nearly so reliable and therefore safety was more directly dependant on redundancy.

It is not so much that the engines were less reliable as the fact that nobody realized or trusted just how reliable they were. From the first, commercial jet engines have been FAR more reliable than the piston engines they replaced; yes, they have gotten more reliable but not by orders of magnitude, just incrementally. The regulations and mindsets in the early years of jet aircraft were based on the experiences with piston engines. It took many years of experience before regulators and operators really grasped the inherent reliability of jet engines.

Quoting rampart (Reply 4):

There were proposals for a twin 727, minus the middle engine.

The original plans for the 737 were just that (very much like the DC-9); it was Joe Sutter that showed them that by putting the engines under the wing that they could gain two rows of passengers with no increase in structural weight. That is why all subsequent twins have had the engines on the wings.

Quoting CALTECH (Reply 36):
Always liked this version,.....

It has no significant functional advantage, and has a weight disadvantage, as the structural support for the horizontal stabilizer adds significant weight. With tail mounted engines it gets the stabilizer out of the way of the mechanics; with wing mounted engines it offers no advantage.

Topic: RE: Why Did Boeing Build The 727?
Username: bohica
Posted 2012-04-25 18:43:09 and read 6902 times.

Quoting BoeingGuy (Reply 67):
They ended up making a modification to UA's original 720s to increase tail height. Not sure of all the history of that. I had read once that the 707-120 at least was a bit less stable to fly than the -320 due to its shorter fuselage. Not sure if the similar sized 720 had the same problem or if the wing and tail changes made it a bit more stable.

I wasn't aware of the taller tail, but the 720 also had a dorsal fin on the bottom of the tail.


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Photo © George Gayuski

Topic: RE: Why Did Boeing Build The 727?
Username: rampart
Posted 2012-04-25 20:01:23 and read 6756 times.

Quoting SEPilot (Reply 73):
That is why all subsequent twins have had the engines on the wings.

Apart from the F28, F100, ERJ, CRJ. And maybe the Yak 42. And the continuation of the DC-9 frame into the MD80 and MD90 series (and technically the COMAC ARJ). Apart from the MDs, these were all smaller jets or derived from smaller jets.

-Rampart

Topic: RE: Why Did Boeing Build The 727?
Username: zippyjet
Posted 2012-04-25 21:11:37 and read 6613 times.

Several years ago I saw different sketches of prototypes that were to become the 727. There was even a crude looking version where there two mounted wing engines like the 737 and other current twins but, on the left wing there was a top mounted engine. I do not make this stuff up. I saw it and sure enough I can't find that site with those pictures. In regard to the why. Back in the day engine technology wasn't where it now is so a twin jet with the capacity of the 727 was not feasible. Of course several years later things changed. Also as others have posted. Eastern wanted three engines for over water flights to the Caribbean. I miss the 727. Back in the day I took if for granted the way I now look at the 737's. Little did I know that my last ever flight on a 727 would be June 6, 1980 on Eastern Airlines flight 172 MIA-BWI. 15 years later when I took my next flight the ailine scene went through revolutionary changes and the 727 was in it's Twilight years.

Topic: RE: Why Did Boeing Build The 727?
Username: CALTECH
Posted 2012-04-25 21:55:05 and read 6547 times.

Quoting boeingmd82 (Reply 68):
The 727 was also the first jetliner to feature a gas turbine auxiliary power unit. If I remember correctly it was installed in the center of the fuselage below deck and vented out through the starboard wing tip. I remember sitting on the ground in an American 727-200 and feeling the thing vibrate under my feet when I was a kid.

It was a afterthought. It was mounted on the keel beam in the main wheel well. It exhausted out through the top of the wing just forward and inboard of the right main gear, except for Northwest birds, their's exhausted through the wing-to-body fairing just above the wing, and they had a powered door to keep the snow out.

Quoting SEPilot (Reply 73):
It has no significant functional advantage, and has a weight disadvantage, as the structural support for the horizontal stabilizer adds significant weight. With tail mounted engines it gets the stabilizer out of the way of the mechanics; with wing mounted engines it offers no advantage.

Really. So the Lockheed Engineers had it wrong with the C-5 and C-141s ? McDonnell-Douglas/Boeing had it wrong with the C-17 ? Airbus Engineers are going to get it wrong with the A-400M ? All the Beech Queen Airs and King Airs too, not to mention the 1900 series ? Or the Italian hotrod, Piaggio P180 Avanti ?


Quoting rampart (Reply 75):
Apart from the F28, F100, ERJ, CRJ. And maybe the Yak 42. And the continuation of the DC-9 frame into the MD80 and MD90 series (and technically the COMAC ARJ). Apart from the MDs, these were all smaller jets or derived from smaller jets.

-Rampart

  

Topic: RE: Why Did Boeing Build The 727?
Username: rwessel
Posted 2012-04-25 22:19:44 and read 6491 times.

Quoting CALTECH (Reply 77):
Really. So the Lockheed Engineers had it wrong with the C-5 and C-141s ? McDonnell-Douglas/Boeing had it wrong with the C-17 ? Airbus Engineers are going to get it wrong with the A-400M ?

At least with the military airlifters, the need for a ramp in the back makes a conventional tail problematic.

Topic: RE: Why Did Boeing Build The 727?
Username: CALTECH
Posted 2012-04-25 23:25:15 and read 6402 times.

Quoting rwessel (Reply 78):
At least with the military airlifters, the need for a ramp in the back makes a conventional tail problematic.

Explain the Lockheed C-130 then ? Douglas C-133 Globemaster ? Fairchild C-123 Provider ? C-119 Boxcar (okay, not conventional, but not a T-tail) ? The De Havilland Canada DHC-4 Caribou ? Alenia C-27J Spartan/G.222 ? Russian AN-124s and the AN-225 ? Many more Antonovs as the AN-8, AN-12, AN-22 and AN-70 ? All of these military transports had ramps and conventional tails fitted.

[Edited 2012-04-25 23:39:23]

Topic: RE: Why Did Boeing Build The 727?
Username: PITingres
Posted 2012-04-25 23:37:09 and read 6363 times.

Quoting Max Q (Reply 63):
However I disagree that technology was not sufficiently advance to have automated the systems if Boeing really wanted to. Keep in mind that the technology existed at the time for the incredible XB70 to fly with only two Pilots (no flight engineer) and the first flight of the 727 was only a year before the Valkyrie.

I do think it was more of a Union issue.

Hmm, I'm not so sure it is that cut and dried.

Even if the technology existed, it may have been too expensive for a mass production airliner like the 727.

We're talking about 1962 to 1964. That was a time of incredibly rapid advances in electronics and especially solid state. I was a kid at the time, but I have most of the Popular Electronics from 1961 on, and in that time period we see a) massive price drops for diodes and transistors, b) significant increases in power handling ability regardless of fabrication method, and c) the beginning of the move from germanium to silicon (with the concomitant resistance to thermal runaway at load). I don't pretend that PE reflects what the military and major manufacturers could get, but it's a pretty good indicator of trends. My guess is that the 727 could have automated more of the flight engineer board, but at a design and manufacturing price point that was out of reach during its design phase.

It would be a little like deciding which logic family to build your design around, during the 1975-1980 period. TTL? Schottky or low-power-Schottky TTL? ECL? CMOS? Things were moving rapidly and a couple years could change the choice.

Quoting SEPilot (Reply 73):
It took many years of experience before regulators and operators really grasped the inherent reliability of jet engines.

And given the low failure rate, it takes years before you can tell whether you're looking at an inherent reliability, or a confluence of advantageous events hiding a mediocre reliability. Fortunately for us, it's the former.

Topic: RE: Why Did Boeing Build The 727?
Username: rampart
Posted 2012-04-25 23:54:52 and read 6342 times.

Quoting CALTECH (Reply 36):
Always liked this version,.....

Me too. Quite the model improv, and beautiful retro paint job. I was trying to do the same on Consetellation model I have. I have that very magazine that lies beneath the model, too. It's well worn.

Quoting CALTECH (Reply 77):
All the Beech Queen Airs and King Airs too, not to mention the 1900 series ? Or the Italian hotrod, Piaggio P180 Avanti ?

   T-tails in small twin pistons and turboprops (and some single) were in vogue in the 70s and 80s. It was seen as some sort of aerodynamic advantage by many, not sure if that advantage still exists since not many new designs have appeared since then. The Diamond twin is most recent, I guess, and it has a t-tail. Quite a bit different than a 727.

-Rampart

Topic: RE: Why Did Boeing Build The 727?
Username: rampart
Posted 2012-04-26 00:19:12 and read 6310 times.

And in the line of tri-engine aircraft that post-dated the 727 (I think there were all of 3, including the Yaks, and not including a tri-engine DC-3 modification), there was this weirdo, the Britten-Normal Mainlander, a 100 passenger or cargo STOL design that used Dart turboprops, the 3rd mounted high on the tail like a Trislander on steroids.


Source: http://www.flightglobal.com/pdfarchive/view/1972/1972%20-%203316.html

I'm not sure who it might have competed with at the time, maybe the Caribou? Antonovs? It was pretty big, said to be Hercules sized. Would have qualified among the most homely looking aircraft in history. Still quite a departure from a 727.

-Rampart

Topic: RE: Why Did Boeing Build The 727?
Username: maxpower1954
Posted 2012-04-26 01:07:36 and read 6230 times.

The 727 had a flight engineer because then current regs required an F/E on any airliner with over 80,000 pounds MTOW. Nothing to do with union issues

The 727 will always be my favorite airliner I flew in my 30 plus year career; excellent flying chracterestics and a real pilot's airplane. It's the airplane us old guys universaly love. and fondly recall. A masterpeice of late 20th century aircraft design.

Consider yourself lucky the next time you see one. And by the way, the Whisperjet slogan referred to how quiet the cabin was inthe front. In the cockpit you couldn't even hear engines running on the -200 anyway..

Topic: RE: Why Did Boeing Build The 727?
Username: BritishB747
Posted 2012-04-26 04:01:03 and read 6084 times.

Quoting mbj2000 (Reply 26):
I was asking myself the same question. The Trident was in fact the "original" design... Maybe the british engineers at that time still believed in fairplay in the aircraft business...

It seems they must have unfortunately. As soon as BEA changed the design for the Trident the potential customers were gone and Boeing cashed in on the situation.

Quoting clydenairways (Reply 27):
Well you have to look at this with the perspectine of Post WW2 era and the relationship between the two countries, and there are plenty of other examples of this "one way transfer".But even saying that, i don't think the final outcome would have been anything different.

No nothing would have been different seeing as the Trident built was a much watered down version of what it should have been.

Quoting connies4ever (Reply 43):
BEA I believe wanted something 727-sized initially, but as you indicated revised the requirements to make the a/c "tuned" for European routes. Which resulted in HS producing a niche a/c that very few other airlines actually wanted. Actually, if BEA had had their way I think they would simply have purchased the 727-100.

Yes I believe you are right. However being government owned they have to prop up the ailing British aircraft industry of the time. A story that seems identical to the BOAC VC-10 purchase.

Regards

Topic: RE: Why Did Boeing Build The 727?
Username: tb727
Posted 2012-04-26 07:28:32 and read 5870 times.

Quoting crash65 (Reply 58):
The real proof that the engineer was needed was during two-engine-inoperative approaches. After making sure the essential electrical bus was covered and doing the major electrical down load flow (pulling those lavatory drain heater circuit breakers was a real finger strength test), you had to drop to your knees with the gear crank handle to manually release the gear up locks, then crank the landing gear in place, individually.

Haha, I just got out of the sim yesterday and had a newbie on the panel doing the single engine approach, had him start cranking the gear down at about 12 miles. Being new to operating the seat itself, he left his seat in the wrong spot and the crank kept hitting it so he put it all the way in, at 200 feet he was finally done and couldn't get his seat slid back so when I looked back and he was sitting wedged on top of his desk and the FO's seat because he couldn't get the seat back out to sit in!

I love flying this airplane!

Topic: RE: Why Did Boeing Build The 727?
Username: AeroWesty
Posted 2012-04-26 07:53:01 and read 5832 times.

Quoting bohica (Reply 60):
IIRC 737's were all Y before the 1980's, so their seating capacity was close to a 721. I never saw an F cabin in a 737 until the early-mud 80's.

I flew in First on a UA 732 in the early 70s. UA ripped out F in the early 80s for a while on the ones dedicated to the short-lived 'Friendship Express' service.

Topic: RE: Why Did Boeing Build The 727?
Username: connies4ever
Posted 2012-04-26 08:13:38 and read 5771 times.

Quoting BritishB747 (Reply 85):
A story that seems identical to the BOAC VC-10 purchase.

As I recall, the original VC10, model 1101 I think was the prototype, was designed for excellent t/o performance from 'colonial' airfields principally in Africa that could not support 707/DC-8 operations. And with a big uncompromised wing plus full span high-lift devices, VC-10 was an excellent performer. A bit more expensive to operate than a 707 or DC-8 in this regard. And that rep dogged it for life.

The Super was a true rival to the 707 and DC-8, intended for straight long-haul trans-at/trans-pac ops. However, too late to the fair. Once went LHR-YUL on the Super and I must say it was a fabulous ride. I was near the front of Y and it was pretty quiet.

After Concorde, the classiest looking jet ever.

Topic: RE: Why Did Boeing Build The 727?
Username: lightsaber
Posted 2012-04-26 08:15:44 and read 5770 times.

Quoting PITingres (Reply 80):
We're talking about 1962 to 1964. That was a time of incredibly rapid advances in electronics and especially solid state.

100% agree. It was also the airframe that the JT8D matured upon so that it was reliable enough for twin service. Recall that why the A-6 engine shared the same core, it was a different low spool.

Quoting rampart (Reply 81):
It was seen as some sort of aerodynamic advantage by many, not sure if that advantage still exists since not many new designs have appeared since then.

The advantage of a T-tail is certain angle of attack stall characteristics. The disadvantage is added weight and maintenance costs. For rear engine aircraft, a T-tail or cruciform tail simplifies engine integration.

We'll still see T-tails on smaller aircraft. But that size keeps shrinking as solid modeling software allows for easier packaging. In particular as putting the engines under (or over) the wing has become the norm. (It saves significant structural weight and opens up volume in the aft of the aircraft that would otherwise be wasted.)

Lightsaber

Topic: RE: Why Did Boeing Build The 727?
Username: FlyMKG
Posted 2012-04-26 10:32:55 and read 5609 times.

Quoting CALTECH (Reply 77):
It exhausted out through the top of the wing just forward and inboard of the right main gear, except for Northwest birds, their's exhausted through the wing-to-body fairing just above the wing, and they had a powered door to keep the snow out.

I found these pictures of NW birds that appear to have the APU exhaust in the same spot as all of the other 727s I've seen. Am I missing something? (Interesting that the late model aircraft in the second picture has an early style outflow valve instead of the more traditional door.)

View Large View Medium
Click here for bigger photo!

Photo © Gary Watt
View Large View Medium
Click here for bigger photo!

Photo © Chaz Hinkle

Quoting maxpower1954 (Reply 83):
And by the way, the Whisperjet slogan referred to how quiet the cabin was in the front. In the cockpit you couldn't even hear engines running on the -200 anyway..

But you can certainly hear the air from the packs!

Quoting tb727 (Reply 86):
Haha, I just got out of the sim yesterday

Do you guys use Cincinnati or Memphis?

FlyMKG

Topic: RE: Why Did Boeing Build The 727?
Username: Max Q
Posted 2012-04-26 11:07:24 and read 5535 times.

Quoting maxpower1954 (Reply 83):


The 727 had a flight engineer because then current regs required an F/E on any airliner with over 80,000 pounds MTOW. Nothing to do with union issues

No. the regulations could have been changed, technology would have allowed a two Pilot Aircraft, it had everything to do with unions.

Topic: RE: Why Did Boeing Build The 727?
Username: CALTECH
Posted 2012-04-26 12:57:31 and read 5395 times.

Quoting FlyMKG (Reply 90):
I found these pictures of NW birds that appear to have the APU exhaust in the same spot as all of the other 727s I've seen. Am I missing something? (Interesting that the late model aircraft in the second picture has an early style outflow valve instead of the more traditional door.)

I might have been mistaken, it might have been a flap over the Apu Exhaust, not in the Wing-To-Body Fairing. It was to keep snow and debris out of the exhaust. Eventually these were removed and just the exhaust grill remained. Saw it on a few Northwest Orient 727s in the 1980s. Here's a TWA 727 with the flap opened.


View Large View Medium
Click here for bigger photo!

Photo © George W. Hamlin



Mod Edit: Please use the thumbnail code to post images from the database.

[Edited 2012-04-27 10:31:22 by srbmod]

Topic: RE: Why Did Boeing Build The 727?
Username: tb727
Posted 2012-04-26 13:18:27 and read 5373 times.

Quoting FlyMKG (Reply 90):
Do you guys use Cincinnati or Memphis?

Cincy, your POI was in there last week with ours doing some bounces. Where do you guys go? The CVG one flies great but if the wind blows or a bird lands on the wires outside they lose power and it's broke for like 3 days.

Topic: RE: Why Did Boeing Build The 727?
Username: SEPilot
Posted 2012-04-26 15:21:06 and read 5223 times.

Quoting rampart (Reply 75):
Apart from the F28, F100, ERJ, CRJ. And maybe the Yak 42. And the continuation of the DC-9 frame into the MD80 and MD90 series (and technically the COMAC ARJ). Apart from the MDs, these were all smaller jets or derived from smaller jets.

You are correct about the smaller jets; I was speaking of full-size airliners and should have so stated. The MD-80's were not new designs, just warmed-over DC-9's, so I was not counting them.

Quoting CALTECH (Reply 77):

Really. So the Lockheed Engineers had it wrong with the C-5 and C-141s ?

These were military planes where efficiency was decidedly secondary. I suspect the reason for using T-tails was to protect the horizontal stabilizers from FOD damage on gravel runways. But yes, both of these would have been more efficient with conventional tails. But as earlier mentioned, these were not civilian transports and had different priorities. As to the Beech products, GA planes are often not as efficient as they could be; I have no idea why they do some of the things they do. The T-tail does have one aerodynamic advantage; it keeps the horizontal stabilizer in undisturbed air, giving a smoother ride, and perhaps marginally less drag. I do not know if it is enough to overcome the added weight; my strong suspicion is that it is not. It also has a big aerodynamic disadvantage; it is possible to get into a deep stall where the wing blanks out the airflow over the horizontal stabilizer making it impossible to recover. This is not possible with a conventional tail.

Topic: RE: Why Did Boeing Build The 727?
Username: Viscount724
Posted 2012-04-26 17:07:27 and read 5124 times.

Quoting Tan Flyr (Reply 37):
Quoting JAAlbert (Reply 32):
Remember when Eastern Airlines referred to its 727s as "Whisper Jets"? That always cracked me up.

Well compared to the B720's or the early DC-8's, they were slightly more quiet.

The "WhisperJet" term (which Eastern also used for the DC-9) was related to the noise level inside the cabin, not outside, and with the rear engines the cabin noise level was very quiet in comparison with the 4-engine jets.

Quoting bohica (Reply 60):
IIRC 737's were all Y before the 1980's, so their seating capacity was close to a 721. I never saw an F cabin in a 737 until the early-mid 80's.

Not at all true. Many early 737s had F class cabins when delivered in the 1960s.

Quoting BoeingGuy (Reply 67):
Quoting connies4ever (Reply 66):
Due to the shorter moment arm, was the fin height raised somewhat ? Never read anything about that.

They ended up making a modification to UA's original 720s to increase tail height. Not sure of all the history of that. I had read once that the 707-120 at least was a bit less stable to fly than the -320 due to its shorter fuselage. Not sure if the similar sized 720 had the same problem or if the wing and tail changes made it a bit more stable.

All 707s and 720s wound up with vertical stabilizers the same height. Early production 707-120s/220s/320s had a 3-foot shorter tail. The British certification authority would not certify BOAC's Rolls-Royce Conway-powered 707-420s with that tail due to instability issues during testing. Boeing responded by increasing the tail height by 3 feet and installing a lower ventral fin to meet the British requirements.

The early models already in service with the short tail were modified with the new tail at Boeing expense over the next couple lf years. The 707-120 also had a small ventral fin added (much shallower than the ventral fin on the -320 and -420). The 720 had the identical tail, including the shallow ventral fin as the modified 707-120.

The ventral fin was eliminated on later production advanced 707-320Bs and all -320Cs as they also had quite a few other changes to the wing/flaps/slats etc. that apparently made the ventral fin unnecessary.

Topic: RE: Why Did Boeing Build The 727?
Username: brons2
Posted 2012-04-26 22:45:55 and read 4931 times.

Quoting SEPilot (Reply 73):
It is not so much that the engines were less reliable as the fact that nobody realized or trusted just how reliable they were. From the first, commercial jet engines have been FAR more reliable than the piston engines they replaced; yes, they have gotten more reliable but not by orders of magnitude, just incrementally. The regulations and mindsets in the early years of jet aircraft were based on the experiences with piston engines. It took many years of experience before regulators and operators really grasped the inherent reliability of jet engines.

The initial JT9Ds on the 747-100 had about the same reliability as radials...of course Pratt eventually ironed it out.

Topic: RE: Why Did Boeing Build The 727?
Username: vc10
Posted 2012-04-27 02:10:08 and read 4821 times.

Quoting Viscount724 (Reply 95):
The "WhisperJet" term (which Eastern also used for the DC-9) was related to the noise level inside the cabin, not outside, and with the rear engines the cabin noise level was very quiet in comparison with the 4-engine jets.

You have forgotten how quiet the cabin was on a certain 4 engine aircraft of the day . Yes it was the VC-10 which was advertised long before Eastern flew their DC-9 as "Swift , SILENT and Supreme " , now they did mean silent in the cabin and not out side

Topic: RE: Why Did Boeing Build The 727?
Username: tymnbalewne
Posted 2012-04-27 02:50:58 and read 4758 times.

Quoting vc10 (Reply 97):
You have forgotten how quiet the cabin was on a certain 4 engine aircraft of the day . Yes it was the VC-10 which was advertised long before Eastern flew their DC-9 as "Swift , SILENT and Supreme " , now they did mean silent in the cabin and not out side


The motto was "Triumphantly Swift, Silent, Serene", not "supreme."

[Edited 2012-04-27 02:51:32]

Topic: RE: Why Did Boeing Build The 727?
Username: vc10
Posted 2012-04-27 03:50:25 and read 4712 times.

Quoting tymnbalewne (Reply 98):
The motto was "Triumphantly Swift, Silent, Serene", not "supreme."

Thanks for correcting me , but they would have added supreme if they had thought about it I am sure. 

Topic: RE: Why Did Boeing Build The 727?
Username: CALTECH
Posted 2012-04-27 07:46:02 and read 4576 times.

Quoting SEPilot (Reply 94):
These were military planes where efficiency was decidedly secondary. I suspect the reason for using T-tails was to protect the horizontal stabilizers from FOD damage on gravel runways. But yes, both of these would have been more efficient with conventional tails. But as earlier mentioned, these were not civilian transports and had different priorities. As to the Beech products, GA planes are often not as efficient as they could be; I have no idea why they do some of the things they do. The T-tail does have one aerodynamic advantage; it keeps the horizontal stabilizer in undisturbed air, giving a smoother ride, and perhaps marginally less drag. I do not know if it is enough to overcome the added weight; my strong suspicion is that it is not. It also has a big aerodynamic disadvantage; it is possible to get into a deep stall where the wing blanks out the airflow over the horizontal stabilizer making it impossible to recover. This is not possible with a conventional tail.

Don't buy it. The C-130 spends a lot of time on unimproved strips. It was made with a so called conventional tail. Efficiency not a factor in military transport planes ? Don't buy it. A T-tail also is a bit further aft with it's moment arm than a conventional tail and being above and away from the fuselage, makes it more effective, so it can be designed smaller and lighter. That might be enough to offset any beefing up that might be needed. Otherwise, instead of the way the C-5 tail was designed, just make it like the AN-124 if it was that critical.

Topic: RE: Why Did Boeing Build The 727?
Username: BritishB747
Posted 2012-04-27 08:31:15 and read 4530 times.

Quoting connies4ever (Reply 88):
As I recall, the original VC10, model 1101 I think was the prototype, was designed for excellent t/o performance from 'colonial' airfields principally in Africa that could not support 707/DC-8 operations. And with a big uncompromised wing plus full span high-lift devices, VC-10 was an excellent performer. A bit more expensive to operate than a 707 or DC-8 in this regard. And that rep dogged it for life.The Super was a true rival to the 707 and DC-8, intended for straight long-haul trans-at/trans-pac ops. However, too late to the fair. Once went LHR-YUL on the Super and I must say it was a fabulous ride. I was near the front of Y and it was pretty quiet.After Concorde, the classiest looking jet ever.

Yes I remember reading about the take of performance being the VC-10s trump card but by the time it entered service many of the airfields in the colonies that it was designed for had extended their runways so that the B707 and DC-8 could operate from them.

I wish there were more of them about but to be fair they are 50 this year and there are still 9 in regular service. A testiment to the aircraft and the engines I would say. Think I will be taking a trip down to Brize Norton this year for some photographs before they become evenmore scarce.

Maybe a contravertial statement but maybe looks even more classy than Concorde. Not that Concorde is ugly of course.

Regards


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