Moderators: richierich, ua900, PanAm_DC10, hOMSaR

 
FlyASAGuy2005
Topic Author
Posts: 3965
Joined: Sun Sep 23, 2007 4:55 am

What Did Boeing Have In Mind When Designing The75?

Sat Apr 04, 2009 6:49 pm

This is partially based on another thread about the A321 being able to do trans-cons. One comment that stuck out was the fact of the 757's weight, wing design, and fuel capacity. I understand that when the 757 came out, it was intended to be able to perform where the 727 was operating out of for years. Example, the 4000+ foot runway in STT before it's extension. It was Eastern, AA, and Carib 727s weekly. This is just one airport.

I don't think back in the 80s, anyone imagined the 757 doing trans-Atlantic ops, yet today, because of its design-engines, wing design, fuselage design, flap design, fuel capacity-it can do trans-cons and short high density ops. From what i've seen in the US domestic market. Any city that receives the 757 on a regular basis is considered a mature market. Most airlines don't throw them around if they don't need to.

Any thoughts/comments are welcome as we brace for the exit of this fine a/c in the next 10-15years (my guess).
What gets measured gets done.
 
roseflyer
Posts: 9602
Joined: Fri Feb 13, 2004 9:34 am

RE: What Did Boeing Have In Mind When Designing The75?

Sat Apr 04, 2009 7:11 pm

The 757s performance capabilities are because of the design goal of it being able to operate out of 5,000ft runways. That necessitated larger powerplants than necessary for a plane of its capacity. The result was that a higher payload was achievable. The higher payload meant more fuel could be carried and that it got significant range capabilities.

Transatlantic was not viewed as a probability when it was designed. The 767 was to do that job. Remember that in 1978 any airline that operated a narrowbody on a transatlantic flight was viewed as inferior. The DC10s, L1011s and 747s were the standard for international flight. Airlines were rapidly dumping the 707 on transatlantic flights, but needed a smaller plane. The narrowest widebody was thus developed in the 767. The 757 was almost viewed as a step backwards in the advancement in aviation with it being a narrowbody. It found an important home on domestic flying in the United States, but that was about it.

The 757 all in all sold well enough and was a popular plane, but it had its downside. Some airlines viewed it as too large and too heavy. It was customized really based on the needs of a few airlines with Eastern barking the loudest (who at the time operated to many inferior airports with short runways especially out of its MIA base to the Caribbean and South America). The airline was not that effective on short routes. Landing fees were high since it had a high payload. The 737 classic series was created based on 757 technology and proved to be far more successful.

With that said, the 757 has a niche. It's a very economical airplane to operate with enough fexibility to operate 40 minute and 6 hour flights. It dominates transcontinental flights now (although that was becoming widebody territory when it was designed). The international niche has seen the swing towards smaller planes with more nonstop destinations and more frequency. While it is a great aircraft like that, we'll probably never see another narrowbody designed that can fly transatlantic. While yes there are quite a few flights now, the market is small. Maybe 10% of the 757s built actually use their range capabilities that exceed the A321 and 737-900ER. On routes under 5 hours, the smaller planes are more efficient.

The 757 is a great plane and I love flying on it. It was a great move forward in aviation that will be around for a while.
If you have never designed an airplane part before, let the real designers do the work!
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: What Did Boeing Have In Mind When Designing The75?

Sat Apr 04, 2009 7:22 pm

I'd always heard the 757-200 was intended to be a modernized 707 replacement...
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
BMI727
Posts: 11300
Joined: Mon Feb 02, 2009 9:29 pm

RE: What Did Boeing Have In Mind When Designing The75?

Sat Apr 04, 2009 7:24 pm

The 757 started out as the 727-300, but it was later decided to design a completely new plane dubbed the 7N7. The goal was to be able to replace the 727-200 and have enough range to do transcons. Field performance was also an important factor. Versatility is a key to the 757s success. It can operate short routes and then turn around for a trans Atlantic flight and make a profit on both.

Quoting RoseFlyer (Reply 1):
Some airlines viewed it as too large and too heavy.

It was for many European flag carriers. They didn't need the range it offered.

Quoting FlyASAGuy2005 (Thread starter):
I don't think back in the 80s, anyone imagined the 757 doing trans-Atlantic ops

No. If they had I think that more European flag carriers would have purchased them. Flying 757s across the pond seems to be a profitable business though.

Quoting RoseFlyer (Reply 1):
The 737 classic series was created based on 757 technology and proved to be far more successful.

On many routes yes, but the 757 has some unique capabilities over the 737 classic. Many of AA's South American routes are only possible thanks to the 757's excellent hot and high performance characterisics.

The 757 may also prove to become an excellent freighter, just like the 727. It should be able to carry a sizeable load quite economically. Plus, there aren't many jets out there that can get as much stuff into a short field as the 757 can. We are just seeing the beginning of the end of Act I. There is a whole different era about to start for the 757.
Why do Aerospace Engineering students have to turn things in on time?
 
474218
Posts: 4510
Joined: Mon Oct 10, 2005 12:27 pm

RE: What Did Boeing Have In Mind When Designing The75?

Sat Apr 04, 2009 9:58 pm

I thought the 757 was designed as the replacement for the 727-200?
 
User avatar
DocLightning
Posts: 22205
Joined: Wed Nov 16, 2005 8:51 am

RE: What Did Boeing Have In Mind When Designing The75?

Sun Apr 05, 2009 2:37 am



Quoting KELPkid (Reply 2):
I'd always heard the 757-200 was intended to be a modernized 707 replacement...

In many ways, it was. It had similar payload, similar performance, but it burned a LOT less fuel.

And to comfortably fly transcon, you actually do need the range of a 757. I've been on a JFK-SFO flight that lasted almost seven hours. That's long enough to do LHR-JFK.

The 739 has about 700NM range less than the 752, and yet flies on 27,500 lb engines rather than the 757's 40K. It carries almost as many passengers and burns a lot less fuel in the process.

And it's not selling terribly well...

The thing was that at the time the 757 was introduced, it was the smallest plane that could do a US transcon. The 73Classics at the time couldn't do it. The 727 couldn't do it. The DC-9/MD-80 couldn't do it. There was no A320 for a few years yet to come...

So at that point, an airline's choice for a coast-to-coast US domestic flight were limited. They could use 707s, but after the fuel crisis of the 70's, they were hot to get rid of those. They could use widebodies, but deregulation favored frequency over capacity, so the 757 was it. And so they snapped it up. Every single major domestic U.S. carrier that existed while the 757 was in production bought it except WN.

In Europe, where the distances are shorter, they enjoyed the MD-80 and 733/4/5, both of which appeared around the same time. The only European flights inaccessible to these craft are the odd corner-to-corner ones, like HEL-SVQ. The only thing the occasional European operator wanted the 757 for was its capacity or for the odd longer route (eg. LHR-TLV). But most of them stuck with the 737 and MD-80.

The A320/73G is more popular because of its smaller capacity. That increases its flexibility, but its range is attractive to U.S. operator without detracting from its efficiency on shorter routes.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
DescendVia
Posts: 141
Joined: Sun Jan 18, 2009 4:26 am

RE: What Did Boeing Have In Mind When Designing The75?

Sun Apr 05, 2009 3:51 am



Quoting 474218 (Reply 4):

I remember seeing a United painted model of the first concept (757-100 maybe?) that had the body and T-tail of a 727 with 2 engines on the wings.
 
vikkyvik
Posts: 12620
Joined: Thu Jul 31, 2003 1:58 pm

RE: What Did Boeing Have In Mind When Designing The75?

Sun Apr 05, 2009 4:09 am



Quoting DocLightning (Reply 5):
The 739 has about 700NM range less than the 752, and yet flies on 27,500 lb engines rather than the 757's 40K. It carries almost as many passengers and burns a lot less fuel in the process.

And it's not selling terribly well...

About this particular case -

If we're not talking about the 739ER (I assume you weren't), then the 738 has the same max capacity (189 if memory serves), but a longer range. The 739 may not be an economical alternative when compared to the 738 for many airlines.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
User avatar
Starlionblue
Posts: 20693
Joined: Fri Feb 27, 2004 9:54 pm

RE: What Did Boeing Have In Mind When Designing The75?

Sun Apr 05, 2009 4:10 am



Quoting DescendVia (Reply 6):
I remember seeing a United painted model of the first concept (757-100 maybe?) that had the body and T-tail of a 727 with 2 engines on the wings.

That would be this one. Here in Braniff colors:

"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
User avatar
DocLightning
Posts: 22205
Joined: Wed Nov 16, 2005 8:51 am

RE: What Did Boeing Have In Mind When Designing The75?

Sun Apr 05, 2009 6:26 pm



Quoting Starlionblue (Reply 8):

That would be this one. Here in Braniff colors:

How odd. I wonder why they went with a T-tail.

Quoting Vikkyvik (Reply 7):
If we're not talking about the 739ER (I assume you weren't), then the 738 has the same max capacity (189 if memory serves), but a longer range. The 739 may not be an economical alternative when compared to the 738 for many airlines.

Boeing only offers a 739ER as far as I can tell.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
BMI727
Posts: 11300
Joined: Mon Feb 02, 2009 9:29 pm

RE: What Did Boeing Have In Mind When Designing The75?

Sun Apr 05, 2009 7:17 pm



Quoting DocLightning (Reply 9):
How odd. I wonder why they went with a T-tail.

I guess it is just because that was what the 727 had. They got rid of it because T-tails are more expensive and prone to deep stalls.

Quoting DocLightning (Reply 5):
In many ways, it was. It had similar payload, similar performance, but it burned a LOT less fuel.

Glancing at the specs yes, but by the time the 757 was being developed, most large carriers had retired their 707s. They were replaced by 727s on shorter routes and the DC-10/L1011 on many longer ones. Now the 757 is flies a combination of routes previously held by any of them.

Quoting DocLightning (Reply 5):
The only thing the occasional European operator wanted the 757 for was its capacity or for the odd longer route (eg. LHR-TLV).

They were attractive to European charter airlines because they had a pretty high capacity and were economical to operate on shorter routes but could also reach points in northern Africa and parts of the Middle East. The large legacy carriers could afford to have many different types to fly routes around Europe and then planes to go to Africa and the Mid East. Charter airlines found it more effective to use one plane for all of them.
Why do Aerospace Engineering students have to turn things in on time?
 
FlyASAGuy2005
Topic Author
Posts: 3965
Joined: Sun Sep 23, 2007 4:55 am

RE: What Did Boeing Have In Mind When Designing The75?

Sun Apr 05, 2009 10:56 pm



Quoting DocLightning (Reply 9):
How odd. I wonder why they went with a T-tail.

Looks quite odd indeed.

I always wonder if there is a 757-like a/c in Boeing's future.
What gets measured gets done.
 
Viscount724
Posts: 19316
Joined: Thu Oct 12, 2006 7:32 pm

RE: What Did Boeing Have In Mind When Designing The75?

Sun Apr 05, 2009 11:12 pm



Quoting DocLightning (Reply 5):
Quoting KELPkid (Reply 2):
I'd always heard the 757-200 was intended to be a modernized 707 replacement...

In many ways, it was. It had similar payload, similar performance, but it burned a LOT less fuel.

The 757 doesn't come close to the 707-320B/C range (and comparable DC-8s). The 757 can't operate routes like LAX-LHR/CDG/FRA, LHR-NRT, SFO/LAX-NRT which were well within 707 and DC-8 capability.

As already mentioned, by the time the 757 first flew, few major passenger carriers were still flying the 707 or DC-8 on international routes.
 
PennStation
Posts: 39
Joined: Wed May 17, 2006 4:03 pm

RE: What Did Boeing Have In Mind When Designing The75?

Mon Apr 06, 2009 1:04 am



Quoting RoseFlyer (Reply 1):
Transatlantic was not viewed as a probability when it was designed. The 767 was to do that job.

I'm not sure that there was anyone at Boeing during the late 70's/early 80's who realistically expected twin engined aircraft to be operating trans-Atlantic services. I remember ETOPS to be a mostly mid-to-late 80's development.
 
vikkyvik
Posts: 12620
Joined: Thu Jul 31, 2003 1:58 pm

RE: What Did Boeing Have In Mind When Designing The75?

Mon Apr 06, 2009 2:29 am



Quoting DocLightning (Reply 9):
Boeing only offers a 739ER as far as I can tell.

That may be the case now. But the original NG 737s included the 739, which wasn't an -ER model, had the same max capacity as the 738 (due to having the same number of exits), with shorter range.
I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
tdscanuck
Posts: 8573
Joined: Wed Jan 11, 2006 7:25 am

RE: What Did Boeing Have In Mind When Designing The75?

Mon Apr 06, 2009 6:13 am



Quoting PennStation (Reply 13):
I'm not sure that there was anyone at Boeing during the late 70's/early 80's who realistically expected twin engined aircraft to be operating trans-Atlantic services. I remember ETOPS to be a mostly mid-to-late 80's development.

That's probably true...as I understand it, it was the carriers (not the OEM's) who saw the potential for ETOPS and worked with the regulators to make it possible. The OEM's supported, obviously, but I'm sure they secretly weren't all that happy about their most lucrative quads being superceded by much cheaper (and lower margin) twins.

Tom.
 
User avatar
HAWK21M
Posts: 30130
Joined: Fri Jan 05, 2001 10:05 pm

RE: What Did Boeing Have In Mind When Designing The75?

Mon Apr 06, 2009 7:03 am



Quoting BMI727 (Reply 3):
The 757 may also prove to become an excellent freighter

Undoubtly....Out here the B752SF & B752PCF are proving to be very successfull.
regds
MEL.
I may not win often, but I damn well never lose!!! ;)
 
roseflyer
Posts: 9602
Joined: Fri Feb 13, 2004 9:34 am

RE: What Did Boeing Have In Mind When Designing The75?

Mon Apr 06, 2009 4:12 pm



Quoting DocLightning (Reply 5):

The 739 has about 700NM range less than the 752, and yet flies on 27,500 lb engines rather than the 757's 40K. It carries almost as many passengers and burns a lot less fuel in the process.

And it's not selling terribly well...

The 739ER has sold better than the 757 did. Yes it is no where near as popular as the 738, but it's being built faster than the 757 rate was. It took 6 years before the 757 rate was increased beyond 3 per month. The 739ER is being built currently at about 4 per month. The 757 did not have high production rate until the early 90s. The 739ER is selling at a comparable rate to the first decade of 757 service.

Quoting DocLightning (Reply 9):
How odd. I wonder why they went with a T-tail.

T-tails cause less drag and are more efficient. However they have poorer stall recovery characteristics, so Boeing opposes their use now for new designs.

Quoting DocLightning (Reply 9):
Boeing only offers a 739ER as far as I can tell.

739 is no longer offered.
If you have never designed an airplane part before, let the real designers do the work!
 
BMI727
Posts: 11300
Joined: Mon Feb 02, 2009 9:29 pm

RE: What Did Boeing Have In Mind When Designing The75?

Mon Apr 06, 2009 4:57 pm



Quoting RoseFlyer (Reply 17):
However they have poorer stall recovery characteristics, so Boeing opposes their use now for new designs.

Aren't they also heavier and more expensive to make due to the extra structure necessary?
Why do Aerospace Engineering students have to turn things in on time?
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: What Did Boeing Have In Mind When Designing The75?

Mon Apr 06, 2009 7:15 pm



Quoting RoseFlyer (Reply 17):
T-tails cause less drag and are more efficient. However they have poorer stall recovery characteristics, so Boeing opposes their use now for new designs.

Not to mention that, due to the necessity for more structure, they are generally heavier than a traditional configuration tail...
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
Viscount724
Posts: 19316
Joined: Thu Oct 12, 2006 7:32 pm

RE: What Did Boeing Have In Mind When Designing The75?

Mon Apr 06, 2009 10:57 pm



Quoting KELPkid (Reply 19):
Quoting RoseFlyer (Reply 17):
T-tails cause less drag and are more efficient. However they have poorer stall recovery characteristics, so Boeing opposes their use now for new designs.

Not to mention that, due to the necessity for more structure, they are generally heavier than a traditional configuration tail...

The T-tail also results in a longer aircraft with less of the overall length usable for passengers and cargo. The shortest DC-9-10 is 4 feet longer than the 737-200 but the 732 has a longer passenger cabin.
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: What Did Boeing Have In Mind When Designing The75?

Mon Apr 06, 2009 11:07 pm



Quoting Viscount724 (Reply 20):
The T-tail also results in a longer aircraft with less of the overall length usable for passengers and cargo. The shortest DC-9-10 is 4 feet longer than the 737-200 but the 732 has a longer passenger cabin.

I would argue, though, in the DC-9's case, that was more a consequence of the selected fuselage width than anything else...after all, the 727 wasn't long and ungainly like an MD-80. Douglas could have used six abreast seating on the DC-9 if the utlimate goal was something as long as the MD-80...  Wink [which I don't think it was...]
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
vikkyvik
Posts: 12620
Joined: Thu Jul 31, 2003 1:58 pm

RE: What Did Boeing Have In Mind When Designing The75?

Mon Apr 06, 2009 11:37 pm



Quoting KELPkid (Reply 21):
Douglas could have used six abreast seating on the DC-9 if the utlimate goal was something as long as the MD-80...

He didn't say "more passengers" though, he said "longer passenger cabin". That's relatively irrespective of how many seats you have abreast. The less structure/fuse you need that isn't occupied by passengers, the better.

Quoting Viscount724 (Reply 20):
The shortest DC-9-10 is 4 feet longer than the 737-200 but the 732 has a longer passenger cabin.

I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 
User avatar
Starlionblue
Posts: 20693
Joined: Fri Feb 27, 2004 9:54 pm

RE: What Did Boeing Have In Mind When Designing The75?

Tue Apr 07, 2009 12:20 am



Quoting Viscount724 (Reply 20):
The T-tail also results in a longer aircraft with less of the overall length usable for passengers and cargo. The shortest DC-9-10 is 4 feet longer than the 737-200 but the 732 has a longer passenger cabin.

Is this more a function of engine placement than tail type?
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Alessandro
Posts: 4961
Joined: Wed Sep 12, 2001 3:13 am

RE: What Did Boeing Have In Mind When Designing The75?

Tue Apr 07, 2009 6:28 am

I think they thought of the South American market as well, many hot´n high airports on that continent.
From New Yorqatar to Califarbia...
 
DfwRevolution
Posts: 9310
Joined: Sat Jan 09, 2010 7:31 pm

RE: What Did Boeing Have In Mind When Designing The75?

Tue Apr 07, 2009 11:36 pm



Quoting DocLightning (Reply 5):
The 739 has about 700NM range less than the 752, and yet flies on 27,500 lb engines rather than the 757's 40K. It carries almost as many passengers and burns a lot less fuel in the process.

And it's not selling terribly well...

Part of that is just low demand for aircraft larger than the A320/738, not the specs of the 739ER or A321. Most of the U.S. airlines had their 757-200s delivered between the late-80s and 2000 so there's really no need to replace them. There won't be another major replacement cycle for perhaps 8-10 years.

Quoting DocLightning (Reply 5):
Every single major domestic U.S. carrier that existed while the 757 was in production bought it except WN.

And even WN considered it seriously. The 757-200 was and still is a CASM machine in an all-economy configuration  thumbsup 
I have a three post per topic limit. You're welcome to have the last word.
 
BMI727
Posts: 11300
Joined: Mon Feb 02, 2009 9:29 pm

RE: What Did Boeing Have In Mind When Designing The75?

Wed Apr 08, 2009 2:55 pm



Quoting DfwRevolution (Reply 25):
The 757-200 was and still is a CASM machine in an all-economy configuration

That is why the charter airlines like it. That and it's versatility. A few LCCs have used them. The new National Airlines comes to mind.
Why do Aerospace Engineering students have to turn things in on time?
 
1GR8AIRLINE
Posts: 4
Joined: Fri Mar 20, 2009 4:29 pm

RE: What Did Boeing Have In Mind When Designing The75?

Wed Apr 08, 2009 4:37 pm



Quoting Starlionblue (Reply 8):
Here in Braniff colors:

I'm curious why the model's in Braniff's early 60s colors. I would think that by the time the 757 configuration reached this stage, Braniff would have been in the "Ultra" livery (or out of business altogether).
 
User avatar
SAA380
Posts: 119
Joined: Fri Mar 28, 2008 11:07 am

RE: What Did Boeing Have In Mind When Designing The75?

Wed Apr 08, 2009 4:42 pm



Quoting Alessandro (Reply 24):
I think they thought of the South American market as well, many hot´n high airports on that continent.

Yeah, we probably would have gotten more of them in JNB with the T tail design than with the current 757.

We maybe get one a week.  Sad

SAA380  airplane 
Hard work always pays.
 
User avatar
DocLightning
Posts: 22205
Joined: Wed Nov 16, 2005 8:51 am

RE: What Did Boeing Have In Mind When Designing The75?

Wed Apr 08, 2009 4:43 pm



Quoting RoseFlyer (Reply 17):

T-tails cause less drag and are more efficient.

Can you elaborate?

Quoting DfwRevolution (Reply 25):

And even WN considered it seriously. The 757-200 was and still is a CASM machine in an all-economy configuration thumbsup

Didn't they have one briefly? I know they had a 727 briefly.

Quoting KELPkid (Reply 21):

I would argue, though, in the DC-9's case, that was more a consequence of the selected fuselage width than anything else...after all, the 727 wasn't long and ungainly like an MD-80. Douglas could have used six abreast seating on the DC-9 if the utlimate goal was something as long as the MD-80... Wink [which I don't think it was...]

Both the DC-9 and 727 had rear-mounted engines primarily so that they could safely operate out of semi-prepared airfields without pulling up all sorts of FOD. My guess is that Boeing realized that semi-prepared airfields were probably not going to be used for planes that size and so they went with the more efficient under-wing placement for all future models. In fact, the 727 is the only Boeing jetliner without wing-mounted engines.

RJ manufacturers still made rear-mounted engines for that very reason. Only recently have they come to realize that, even in the third world, semi-prepared airfields are so rare that it simply isn't worth the costs of rear-mounting the engines
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
User avatar
Starlionblue
Posts: 20693
Joined: Fri Feb 27, 2004 9:54 pm

RE: What Did Boeing Have In Mind When Designing The75?

Wed Apr 08, 2009 11:52 pm

Quoting 1GR8AIRLINE (Reply 27):

I'm curious why the model's in Braniff's early 60s colors. I would think that by the time the 757 configuration reached this stage, Braniff would have been in the "Ultra" livery (or out of business altogether).

Hmmm, never thought of that. But I guess early concepts of the 757 came out in the 70s.

Quoting DocLightning (Reply 29):
RJ manufacturers still made rear-mounted engines for that very reason. Only recently have they come to realize that, even in the third world, semi-prepared airfields are so rare that it simply isn't worth the costs of rear-mounting the engines

It's not the only reason. A short gear (allowing you short airstairs and simpler loading/unloading) is another.

[Edited 2009-04-08 16:53:53]
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Max Q
Posts: 8974
Joined: Wed May 09, 2001 12:40 pm

RE: What Did Boeing Have In Mind When Designing The75?

Thu Apr 09, 2009 11:19 pm

Love the T tail 757 model, looks great, I notice it has eyebrow windows as well.



Unfortunately it's not really practical, adding lots of unnecessary structure and resulting weight.
The best contribution to safety is a competent Pilot.


GGg
 
FlyASAGuy2005
Topic Author
Posts: 3965
Joined: Sun Sep 23, 2007 4:55 am

RE: What Did Boeing Have In Mind When Designing The75?

Sat Apr 11, 2009 2:03 am

I'd also like to ask another question. There was anothe topic about US, TZ, and NA having true "heavy" 757s because of their weight; fuel tanks I believe. Did they loose and cargo space for them?
What gets measured gets done.
 
User avatar
DocLightning
Posts: 22205
Joined: Wed Nov 16, 2005 8:51 am

RE: What Did Boeing Have In Mind When Designing The75?

Sat Apr 11, 2009 4:36 am



Quoting Starlionblue (Reply 30):

It's not the only reason. A short gear (allowing you short airstairs and simpler loading/unloading) is another.

Didn't the 732 have built-in airstairs?
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
tdscanuck
Posts: 8573
Joined: Wed Jan 11, 2006 7:25 am

RE: What Did Boeing Have In Mind When Designing The75?

Sat Apr 11, 2009 5:44 am



Quoting DocLightning (Reply 33):

Didn't the 732 have built-in airstairs?

Not sure it's on the 732, but it's an option on all current production 737's and it was on the 727, so I'd assume it was on the aircraft in between.

Tom.
 
User avatar
Starlionblue
Posts: 20693
Joined: Fri Feb 27, 2004 9:54 pm

RE: What Did Boeing Have In Mind When Designing The75?

Sat Apr 11, 2009 6:44 am



Quoting DocLightning (Reply 33):
Quoting Starlionblue (Reply 30):

It's not the only reason. A short gear (allowing you short airstairs and simpler loading/unloading) is another.

Didn't the 732 have built-in airstairs?

Even if it's built in, a shorter gear means less stairs to haul around = less weight and complexity. Many of the smaller commuters/corpojets have the stairs on the inside of the door.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
User avatar
DocLightning
Posts: 22205
Joined: Wed Nov 16, 2005 8:51 am

RE: What Did Boeing Have In Mind When Designing The75?

Sat Apr 11, 2009 11:55 pm



Quoting Starlionblue (Reply 35):

Even if it's built in, a shorter gear means less stairs to haul around = less weight and complexity. Many of the smaller commuters/corpojets have the stairs on the inside of the door.

Part of that is because there really isn't another practical place to put it.

But remember, we're talking about an A320/737-sized plane here. The manufacturer can safely assume that 99+% of airports at which these planes will land will have a set of airstairs available.

I can't think of an airport that is so poorly-resourced as to not have airstairs that merits a plane with 100+ seats. Generally, if an airline feels that there is enough demand to serve a given airport with a plane that big, the airline will purchase airstairs, which aren't exactly an expensive/high-tech piece of equipment. This is precisely why neither the 737 nor the A320 feature built-in airstairs.

So in considering rear-mounted engines on the 737/A320 successor, I don't think airstairs really justify the disadvantages.
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
FlyASAGuy2005
Topic Author
Posts: 3965
Joined: Sun Sep 23, 2007 4:55 am

RE: What Did Boeing Have In Mind When Designing The75?

Sun Apr 12, 2009 3:52 am



Quoting FlyASAGuy2005 (Reply 32):
I'd also like to ask another question. There was anothe topic about US, TZ, and NA having true "heavy" 757s because of their weight; fuel tanks I believe. Did they loose and cargo space for them?

Think I found my answer in another thread but can someone confirm? "The 757 can structurally handle 255k but it will need a paperwork upgrade. So basically you're not adding weight i.e. fuel tanks. It can technically stay the same but raise the MTOW but the only reason why you would do that is if you intend on hauling more-hence fuel."
What gets measured gets done.
 
tdscanuck
Posts: 8573
Joined: Wed Jan 11, 2006 7:25 am

RE: What Did Boeing Have In Mind When Designing The75?

Sun Apr 12, 2009 5:40 pm



Quoting DocLightning (Reply 36):
But remember, we're talking about an A320/737-sized plane here. The manufacturer can safely assume that 99+% of airports at which these planes will land will have a set of airstairs available.

That's generally true, but it doesn't mean they'll actually use the airport airstairs. Ryanair intentionally uses the aircraft airstairs just so they don't have to pay the airport operator, even when airport airstairs are available.

Quoting DocLightning (Reply 36):
This is precisely why neither the 737 nor the A320 feature built-in airstairs.

The 737 can have built-in airstairs. I'm not sure about A320. It's an option, not standard, but it's a fairly popular option (way way more than 1%).

Tom.
 
PGNCS
Posts: 2268
Joined: Sun Apr 15, 2007 5:07 am

RE: What Did Boeing Have In Mind When Designing The75?

Tue Apr 21, 2009 5:56 pm



Quoting BMI727 (Reply 3):
The 757 may also prove to become an excellent freighter, just like the 727. It should be able to carry a sizeable load quite economically. Plus, there aren't many jets out there that can get as much stuff into a short field as the 757 can. We are just seeing the beginning of the end of Act I. There is a whole different era about to start for the 757.

BMI: I think you have the right idea. The 757 will be flying for many years to come, although not necessarily with major passenger carriers. There is no doubt that their future is generally bright as a freighter.

Quoting FlyASAGuy2005 (Thread starter):
Any thoughts/comments are welcome as we brace for the exit of this fine a/c in the next 10-15years (my guess).

I think BMI got it right; think of it not as an exit, but as a second career in the making.  Smile

Quoting FlyASAGuy2005 (Reply 11):
I always wonder if there is a 757-like a/c in Boeing's future.

I doubt it as a standalone product. The vast majority of the 757 missions can be done much more economically with a 737 or A-320 series aircraft.

Quoting DocLightning (Reply 29):
Quoting KELPkid (Reply 21):

I would argue, though, in the DC-9's case, that was more a consequence of the selected fuselage width than anything else...after all, the 727 wasn't long and ungainly like an MD-80. Douglas could have used six abreast seating on the DC-9 if the utlimate goal was something as long as the MD-80... Wink [which I don't think it was...]

Both the DC-9 and 727 had rear-mounted engines primarily so that they could safely operate out of semi-prepared airfields without pulling up all sorts of FOD. My guess is that Boeing realized that semi-prepared airfields were probably not going to be used for planes that size and so they went with the more efficient under-wing placement for all future models. In fact, the 727 is the only Boeing jetliner without wing-mounted engines.

Doc: For the second time today, I have to tip my hat to you! You eloquently introduced the concept of design trades with a great example. Different aircraft are optimized different ways to meet the requirements set forth by the market. Different planes will look and act differently because of choices made by engineers (and marketers) trying to maximize the appeal of the aircraft. Some are successful and some are unsuccessful, and itierative learning occurs in the next design cycle.

Quoting DocLightning (Reply 33):
Didn't the 732 have built-in airstairs?

It was at least an option. At least some of ours had them, but I believe they were all removed eventually for weight.
 
BMI727
Posts: 11300
Joined: Mon Feb 02, 2009 9:29 pm

RE: What Did Boeing Have In Mind When Designing The75?

Tue Apr 21, 2009 7:19 pm



Quoting PGNCS (Reply 39):
It was at least an option. At least some of ours had them, but I believe they were all removed eventually for weight.

At least some have them. The first time I ever saw integral airstairs was in the movie Miracle Landing, which really used and Aloha 732.
Why do Aerospace Engineering students have to turn things in on time?
 
Viscount724
Posts: 19316
Joined: Thu Oct 12, 2006 7:32 pm

RE: What Did Boeing Have In Mind When Designing The75?

Tue Apr 21, 2009 11:55 pm



Quoting DocLightning (Reply 36):
This is precisely why neither the 737 nor the A320 feature built-in airstairs.

Not correct. All or almost all early 737s had built-in airstairs and they're still being ordered on some 737NGs 40 years later.


View Large View Medium
Click here for bigger photo!

Photo © Anton Dahlberg
View Large View Medium
Click here for bigger photo!

Photo © Pawel Padewski

 
DaBuzzard
Posts: 66
Joined: Fri Sep 07, 2007 6:11 am

RE: What Did Boeing Have In Mind When Designing The75?

Wed Apr 22, 2009 5:23 pm



Quoting DocLightning (Reply 36):
This is precisely why neither the 737 nor the A320 feature built-in airstairs.



Quoting Viscount724 (Reply 41):
All or almost all early 737s had built-in airstairs

Indeed, some were even at the back door.....

Big version: Width: 620 Height: 465 File size: 111kb
 
BMI727
Posts: 11300
Joined: Mon Feb 02, 2009 9:29 pm

RE: What Did Boeing Have In Mind When Designing The75?

Wed Apr 22, 2009 7:26 pm



Quoting DaBuzzard (Reply 42):
Indeed, some were even at the back door.....

That is right. I think I remember seeing a pic of an AS 732 with them, but I might be mistaken.
Why do Aerospace Engineering students have to turn things in on time?
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: What Did Boeing Have In Mind When Designing The75?

Wed Apr 22, 2009 11:32 pm



Quoting Tdscanuck (Reply 38):
I'm not sure about A320.

I don't think built-in airstairs are an option for the A320 series. I flew on AK a little over a year ago in Malaysia, talk about an operation that could use integral air stairs! They are an FR clone, and everywhere they flew, they were met by not one, but two (!) of the old-style trucks with stairs on the back of the truck body (just like they did here in the 'states until jetways were common). Heck, that's how you boarded your flight at ELP until they remodeled and added jetways in 1981  Smile (before that, only AA's gates had jetways).
Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 
FlyASAGuy2005
Topic Author
Posts: 3965
Joined: Sun Sep 23, 2007 4:55 am

RE: What Did Boeing Have In Mind When Designing The75?

Thu Apr 23, 2009 12:26 am



Quoting Tdscanuck (Reply 38):
I'm not sure about A320

You're right. Good example is Ryanair and the new C-40s for the US Navy and Air Force. I've also seen pictures of the Airbus with air

Quoting KELPkid (Reply 44):

I know someone will find the photo or at least post one because i've seen it before, but I had seen an A318/19/20 (don't know what type) with built-in air stairs.
What gets measured gets done.
 
Viscount724
Posts: 19316
Joined: Thu Oct 12, 2006 7:32 pm

RE: What Did Boeing Have In Mind When Designing The75?

Thu Apr 23, 2009 2:26 am



Quoting DaBuzzard (Reply 42):
Quoting Viscount724 (Reply 41):
All or almost all early 737s had built-in airstairs

Indeed, some were even at the back door.....

I believe the 737-200C combis were the only ones with the rear airstairs since that was the main passenger door when used in combi configuration. The downward-hinged rear door on the combis to which the airstair is attached is also wider than on other 737s where the rear door is quite narrow. Many if not all 732C combis also had the forward airstairs, although as already mentioned some carriers remoed the airstairs later to reduce weight.

Quoting KELPkid (Reply 44):
Quoting Tdscanuck (Reply 38):
I'm not sure about A320.

I don't think built-in airstairs are an option for the A320 series.

I've never seen an A320 (or 318/319/321) with airstairs. They would also be longer and heavier than 737 airstairs since the A320 cabin floor is about 2.5 ft. further from ground level than on the 737.
 
MSPNWA
Posts: 3698
Joined: Thu Apr 23, 2009 2:48 am

RE: What Did Boeing Have In Mind When Designing The75?

Thu Apr 23, 2009 3:45 am



Quoting BMI727 (Reply 43):
I think I remember seeing a pic of an AS 732 with them, but I might be mistaken.

You're not mistaken. I have a picture of the then-active AS 737-200C (N740AS I think) with the rear airstairs deployed out the port side.
 
User avatar
DocLightning
Posts: 22205
Joined: Wed Nov 16, 2005 8:51 am

RE: What Did Boeing Have In Mind When Designing The75?

Thu Apr 23, 2009 4:58 am



Quoting Viscount724 (Reply 41):

Not correct. All or almost all early 737s had built-in airstairs and they're still being ordered on some 737NGs 40 years later.

It's not a popular option and now that it's no longer 1963, airstairs are much less popular. So airstairs are generally an afterthought in designing an aircraft and don't factor into engine placement, which was my original point.

Some 737's will continue to serve truly backwards airports or special missions which require built-in airstairs. However, since most airports have at least a simple, hand-pushed set of airstairs capable of reaching a 737 or A320...
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
ha763
Posts: 3201
Joined: Mon Jan 06, 2003 5:36 pm

RE: What Did Boeing Have In Mind When Designing The75?

Thu Apr 23, 2009 7:33 am



Quoting FlyASAGuy2005 (Reply 45):

I know someone will find the photo or at least post one because i've seen it before, but I had seen an A318/19/20 (don't know what type) with built-in air stairs.

The only A32X with built-in air stairs I have all been private jets. It's probably not an option for commercial airlines. Here's an A318 ACJ with built-in air stairs:


View Large View Medium
Click here for bigger photo!

Photo © Jacques Lienard

Who is online

Users browsing this forum: Horstroad and 7 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos