757 series or A320 series

[MrSuupaFly]

The B757 has a higher MMo than the A320.

 

[Whine Lover]

Thrust-To-Weight...A Primer:

I am a Large Fat Man. I have Mass. Once set in motion, the "Thrust" Level becomes quite impressive.

In fact, my second Ex-Wife once required Dental Work due to an unauthorized re-entry procedure, utilizing a "skip" method from the "Taint" Area.

Now, only utilizing 4.5 inches of Instrument, I was able to "Pile Drive" ( If you will ) several incisors from said recipients forward Dental Appendages.

Mass and Inertia. "The Fat Man's Friend."

But, I digress...


YKW

 

[elag777]

Interesting web site to check out the IAE product


http://www.v2500.com/engine/index.shtm

 

[FL420]

This hasd been covered in a previous thread so forgive me if I just borrow from my previous post(s.) I only have firsthand experience with the A320 and the B757 so can only compare the two.

In general, my ideal single-aisle airliner would be the B757 Rolls-Royce engines, wing and brakes mated to the A321 fuselage and flightdeck, systems design philosophy, fly-by-wire with sidesticks and engine FADEC's.

Specifically:
Flat floor w/o seat tracks that try to twist your ankle and rip the heels off your shoes. You can also spread a blanket on the carpeted floor and sleep behind the seats on those long augmented out and back turns. Score one for the Bus.

Dark overhead panel philosophy with mostly flat pushbutton switches to minimize damage to your head if you forget to duck. Great human factors engineering with flow lines for systems. Score one for the Bus.

Much better design on cup holders, pilot sunshades and side window shades on the A320. Score one for the Bus.

Sidesticks allow you to put the aircraft where you want it to go with just minute movement of the wrist. You do need to properly adjust your armrest. Score one for the Bus.

The tray. What can I say? It holds a lunch, a laptop and all the paperwork we still have to do flying internationally. You can cross your legs and spin around in your seat. Score a big one for the Bus.

The Intel 8086(or 8088) processor on the earlier A320's was way too slow. It was very easy to out-type the processor and just when you went to line-select a scratchpad entry, the waypoints would re-shuffle and your entry would end up on the wrong line. Also, the processor would only read the MCP every half-second making it imperative to verify the MCP entry on the FMA before moving on to other tasks. Even though both FMS's were made by Honeywell, the B757 FMS was less capable but more intuitive than the A320 FMS. FMS's have been greatly improved in later versions of both aircraft. Score one for the Boeing.

I personally preferred the conventional hydraulic steel brakes on the B757 to the brake-by-wire carbon brakes on the A320. I liked the feel and perceived effectiveness of the steel brakes better. Cockpit readouts of brake temperatures and brake fans for quick turns on the A320 were nice. Score a draw on brakes.

The IAE V2500 engines on the A320 configured for all-coach class(29 rows, 174 seats) weren't always up to the task for the passenger loads and stage lengths we flew. Had to make many bleeds/packs off takeoffs. Never had to do that in the B757 with either the RR or P&W engines. You can never have too much power. Score one for the Boeing.

The A320 was only certified to FL390 while the B757 was certified to FL420. That extra 3,000 feet was pretty useful when trying to stay out of the tops of Wx. Never any worries about the strength or lifting ability of the wing on the B757. Score one for the Boeing.

The fuselage diameter on the A320 family is 7.6 inches greater than on all the single-aisle Boeings. This allows each coach seat and the aisle to have an average of an inch extra width. There is more headroom and more room for overhead bins also. Score one for the Bus.

The A320 had vacuum lavs which were very noisy(hard to sleep in the back row on crew rest) and somewhat cantankerous but saved the weight of 5 gallons of blue water per lav. The B757 lavs hold 9 gallons of liquid each of which 5 gal. is fresh blue juice. Much quieter, heavier and often stinkier and always the possibility of a flush motor overheating. Vacuum lavs more suitable on a long-range aircraft ala B767 and B777. Score a draw on lavs.

The AFCS in the A320 family has very effective low speed/high AOA and high speed/low AOA protections regardless of whether or not an autopilot or A/THR(autothrust) is engaged. If you get too slow or too fast in the coffin corner of the flight envelope, the AFCS will add power up to TOGA and pitch down or reduce power to idle and pitch up to keep you in the envelope. Many pilots of aircraft w/o this feature have stalled or oversped in this flight regime. Score one for the Bus.

The A320 family FMS automatically calculates Vapp which is the Airbus equivalent of Boeing's Vref with headwind component speed adjustments. A major improvement is that it incorporates windshear protection by adjusting Vapp using a feature called GS Mini(minimum groundspeed.) The A/THR adds power to keep a minimum groundspeed in a strong headwind so as to not leave the aircraft in a low energy state with reduced power if the headwind suddenly goes away or shears to a tailwind as might happen when encountering a microburst close to the ground. Score one for the bus.

Finally, the aircraft climb performance is optimized and the pilot technique is simplified during windshear recovery and GPWS terrain avoidance escape maneuvers. In the Boeing you must pitch up to and nibble at the stickshaker while going to TOGA and retracting speedbrakes. In the Airbus you pull the stick back and hold it while the AFCS optimizes the AOA for best climb performance. Score one for the Bus.

Aesthetically, I don't think a better-looking airliner than the B757 was ever built, with the possible exception of the Lockheed L-1049 Super Connie. Score one for the Boeing.

 

[zonker]

Wow, great post 420. Very interesting read.

 

[accinelli]

Which one is better? In response to the AA thread I wondered what the pilots of this great board opinion was on a direct comparison between both aircraft.

Not only as far as jumpseat comfort,passenger comfort but also,but more importantly which is a better plane to fly from a pilots perspective.

I vote for the 757. It besides the 727 is my favorite plane.

The A320 has a lower overall cost of Operation. Anyone get the picture now.

 

[PowerRanger]

One big factor is the wing sweep. The 757 is 25 degrees and the A320 is 35 degrees. The A320 will cruise faster, the 757 will cruise more economically. It also improves the climb perfromance with the less swept wing.

The thrust ratings on those engines varied between 22,000 lbs and 27,000 lbs of thrust per engine.

I'd say that engine thrust on the A320 engines does sound very under powered. As for wing sweepage I knew the 757 was at 25 degrees but I didn't know the A320 was swept at 35 degrees!

Thanks guys keep it all coming. Learning alot!

 

[filejw]

This is a great post but having flown both I tell people who ask fly the one that has the best trips and working conditions.

 

[ultrarunner]

The bus has a higher sweep, resulting in a higher critical mach and it's got a lower MMO which is interesting.

One of the reasons to increase the sweep is to increase the critical mach, which then in turn increases normal opeating mach resulting in higher cruise speeds.

What's mmo on the boeing, .84 or so? And .82 on the bus? I'd imagine it's going to take a fair amount of fuel to push that straighter wing to higher mach numbers, not to mention the overall weight. So it's not hard to understand why the bus wins out on cost of operation especially if you've configured it for higher density seating.

Interesting discussion.

 

[clickclickboom]

The bus has a higher sweep, resulting in a higher critical mach and it's got a lower MMO which is interesting.

One of the reasons to increase the sweep is to increase the critical mach, which then in turn increases normal opeating mach resulting in higher cruise speeds.

What's mmo on the boeing, .84 or so? And .82 on the bus? I'd imagine it's going to take a fair amount of fuel to push that straighter wing to higher mach numbers, not to mention the overall weight. So it's not hard to understand why the bus wins out on cost of operation especially if you've configured it for higher density seating.

Interesting discussion.

I fly the 320 for JB... I have never flown a 757 just admired them from afar

Super comfortable plane.. The sidestick while cool is more artificial in feel than your joystick you use for microsoft flight sim at home.

Which plane would i rather fly? The 757 any day of the week.. An american built plane built by americans in america. Aluminum has been proven for years unlike the composite material which the majority of the bus tail is made of.

 

[Country Wild]

Why are we comparing a A320 to a 757, shouldn't it be an A320 compared to a B737 and a B757 compared to an A321? Going Boeing or Go Home!!!

 

[Ben Franklin]

Q. How can you tell the difference between the B757 pilot and the A320 pilot at the bar?

A. The A320 pilot has nothing bewteen his legs.

I keed! I keed!



Sincerely,

B. Franklin

 

[PowerRanger]

The bus has a higher sweep, resulting in a higher critical mach and it's got a lower MMO which is interesting.

One of the reasons to increase the sweep is to increase the critical mach, which then in turn increases normal opeating mach resulting in higher cruise speeds.

What's mmo on the boeing, .84 or so? And .82 on the bus? I'd imagine it's going to take a fair amount of fuel to push that straighter wing to higher mach numbers, not to mention the overall weight. So it's not hard to understand why the bus wins out on cost of operation especially if you've configured it for higher density seating.

Interesting discussion.

What is MMO?

 

[j41driver]

Yes, 36,000 lbs to 43,000 lbs of thrust PER MOTOR. On the -200 there are two pratt variants and two rolls variants.

The two pratts are 36.6 and 40.1
The two Rolls are 40.2 and 43.5

Those thrust ratings are PER MOTOR. And, as you know, the 75 has two motors.

You should be up to speed now in checking my calculations.

Technically the 757 has 2 engines. It has a lot more motors than that.

 

[GogglesPisano]

Patriot328, where are you????