Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

B767 vs B737

Wikiposts
Search
Tech Log The very best in practical technical discussion on the web

B767 vs B737

Thread Tools
 
Search this Thread
 
Old 11th Aug 2004, 07:12
  #1 (permalink)  
Thread Starter
 
Join Date: Mar 2003
Location: mauritius
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
B767 vs B737

I'm just wondering why a B767 has got a shorter TODR than a B737. Anyone......?
Brajiv is offline  
Old 11th Aug 2004, 07:15
  #2 (permalink)  
 
Join Date: Jul 2004
Location: Australia
Posts: 139
Likes: 0
Received 0 Likes on 0 Posts
May I please add to the question? What is TODR? Thanks
Capt. J is offline  
Old 11th Aug 2004, 07:19
  #3 (permalink)  
Thread Starter
 
Join Date: Mar 2003
Location: mauritius
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
Sorry, i meant T/O roll
Brajiv is offline  
Old 11th Aug 2004, 07:34
  #4 (permalink)  
 
Join Date: Jul 2004
Location: Australia
Posts: 139
Likes: 0
Received 0 Likes on 0 Posts
It depends on where it's going. The 767 generally has more power than a 737. If the 767 fills up with full fuel, then it'd be heavier and take up more runway. If it's a short distant flight, it will use less fuel therefore lighter and use less runway but still have as much power which is more than the 737.

The 737 is lighter than the 767 but the 767 has more power than the 737. Again I say, depends on how much fuel is put on the aircraft.
Capt. J is offline  
Old 11th Aug 2004, 13:02
  #5 (permalink)  
 
Join Date: Jun 2001
Location: FNQ ... It's Permanent!
Posts: 4,294
Received 169 Likes on 86 Posts
The 767 generally has more power than a 737
the 767 has more power than the 737
Well, which one is it Capt.J
Does the 767 have more power than the 737 or not.
The 737 is lighter than the 767 but the 767 has more power than the 737. Again I say, depends on how much fuel is put on the aircraft.
Please explain what this statement means..?
Capt Fathom is offline  
Old 11th Aug 2004, 13:57
  #6 (permalink)  
 
Join Date: Aug 2000
Location: cambridge uk
Posts: 288
Likes: 0
Received 0 Likes on 0 Posts
Take off distance required = TODR, and if i remember correctly it is to the screen height of 30ft.

Captain J - do you mean that a 73 has a better thrust to weight ratio at MAUW? or do you think that a 733 with 22k rated engines has more thrust than a 762?
(i dont fly the 767 so have not a clue on its potential thrust available.

because i think the 767 will whip up the 737 every time.
eagerbeaver is offline  
Old 11th Aug 2004, 15:56
  #7 (permalink)  
 
Join Date: Mar 2003
Location: Estados Unidos
Posts: 32
Likes: 0
Received 0 Likes on 0 Posts
Brajiv,

I believe the answer lies in the simple difference of wing design.

To put it very simply (while acknowledging the numerous variables including flap setting, weight, engine de-rate, etc.), the wing on the 737 often requires a greater speed to fly, and it therefore often takes a longer distance to achieve that speed.

Just remember that the above-mentioned variables play a huge part.
Crótalo is offline  
Old 12th Aug 2004, 04:25
  #8 (permalink)  
 
Join Date: Sep 1999
Location: ME
Posts: 5,502
Likes: 0
Received 0 Likes on 0 Posts
Brajiv,

why a B767 has got a shorter TODR than a B737
The short answer is that it doenst!!! You can get a B737-700 off a 5200 ft runway at MTOW while the B767-200 would need 6000 ft.

However the answer isnt as simple as that due to the variation of available engine thrust ratings and restricted takeoff weights. Have a look at these documents and you can judge the differences.

http://www.boeing.com/assocproducts/...s/7672sec3.pdf
http://www.boeing.com/assocproducts/...s/7371sec3.pdf
http://www.boeing.com/assocproducts/...s/7373sec3.pdf
http://www.boeing.com/assocproducts/...s/737wsec3.pdf

Capt J, I thought that TODR was a universal term, did they teach you something else for the Australian Performance "A" exams?


Mutt.
mutt is offline  
Old 13th Aug 2004, 04:56
  #9 (permalink)  
Thread Starter
 
Join Date: Mar 2003
Location: mauritius
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
Thanks Mutt,
but i believe that they've been a lot of modification. I'm at an airport where there's a lot of 73/76's t/o and both types of a/c seems to lift off around the same area of rwy even though the B737 starts its t/o roll 500-600m longer. I've only seen the 737- 700 & 800 series. i cant make any comment on the 400 series.
Crotalo's answer seems to be right.....better check....

Cheers
Brajiv is offline  
Old 13th Aug 2004, 05:38
  #10 (permalink)  
 
Join Date: Sep 1999
Location: ME
Posts: 5,502
Likes: 0
Received 0 Likes on 0 Posts
Brajiv,

Its impossible for a lay person to compare two aircraft taking off and come to a conclusion about their abilities.
All you can do is deal with the facts that Mr Boeing gives you and then educate yourself about derated engines, assumed temperature takeoffs, improved climb, flap selection and finally takeoff weights.
As an airline, we strive to reduce the takeoff power so much that the aircraft will use all of the runway regardless of takeoff weight!

Mutt.
mutt is offline  
Old 15th Aug 2004, 10:33
  #11 (permalink)  
 
Join Date: Aug 2002
Location: there
Posts: 770
Likes: 0
Received 7 Likes on 4 Posts
It has been mentioned in other forums that the 700/800 series of the 73 family has faily 'ordinary' field performance in that at MTOW it requires a greater TODR than the 300/400/500 series - of course the MTOWs are greater but with a wing that is not a great deal larger and also possibly a lower power/weight ratio (?) TODR is going to increase.


Any 73 drivers to confirm (or deny) ?
slice is offline  
Old 15th Aug 2004, 15:38
  #12 (permalink)  
 
Join Date: Sep 1999
Location: ME
Posts: 5,502
Likes: 0
Received 0 Likes on 0 Posts
Just dealing with facts, based on ISA conditions, FAR takeoff requirements and the highest thrust available for each engine type, the required runway length requirements are:

-300 (63,270 kgs) = 7200 ft.
-400 (68,040 kgs) = 8300 ft.
-500 (60,550 kgs) = 8100 ft.
-700 (70,080 kgs) = 5200 ft.
-800 (79,016 kgs) = 6800 ft.
-900 (79,016 kgs) = 7300 ft.

Guess that its fair to say that the NG is the better performer

Please remember that we live in a world of derated thrust, we are planning to use ALL or at least most of the runway!

Mutt.
mutt is offline  
Old 16th Aug 2004, 04:33
  #13 (permalink)  
 
Join Date: Feb 2004
Location: NE YSCN
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
Capt. J

Capt. J,

Best wishes for your thirteenth birthday. Good luck with High School when you start!

B
Bringelly is offline  
Old 16th Aug 2004, 16:55
  #14 (permalink)  
 
Join Date: Dec 2003
Location: Dubai
Posts: 212
Likes: 0
Received 0 Likes on 0 Posts
Hello Mutt,

You are right, but the figures that you state relay on the brakes as well as engines and wing.

Another interesting angle would be to compare the climb limit weight for the first certified T/O flap setting under ISA and ISA + 15. This would compare the aircraft based on wing and engines only.

Any numbers ?
Cap 56 is offline  
Old 16th Aug 2004, 18:28
  #15 (permalink)  
mbga9pgf
Guest
 
Posts: n/a
TODR=Take Off distance required, for CAA performance group A is from brakes off including initial climb to a screen height of 35 feet
 
Old 16th Aug 2004, 20:43
  #16 (permalink)  
 
Join Date: Dec 2003
Location: Dubai
Posts: 212
Likes: 0
Received 0 Likes on 0 Posts
and the second segment starts just after that

......to be exact ..just from gear up..... completely independant from the runway...what are you trying to proof
Cap 56 is offline  
Old 16th Aug 2004, 21:08
  #17 (permalink)  
 
Join Date: Sep 1999
Location: ME
Posts: 5,502
Likes: 0
Received 0 Likes on 0 Posts
Cap 56, i believe that he was stating that the TORA went to 35 feet rather than the 30 feet stated by a previous poster! I dont feel like compounding his confusion by stating tha the screen height is only 15 feet in certain cases......

As for you original question, considering that they are all twin engine aircraft, so the climb limit for the NG aircraft are going to show higher weights! I think that what you are looking for may lie in the ALL engine accelerate go distance shown in the community noise document. Unfortunately i dont have access to that document for the 737 fleet.


Cheers

Mutt.
mutt is offline  
Old 17th Aug 2004, 02:38
  #18 (permalink)  
swh

Eidolon
 
Join Date: May 2001
Location: Some hole
Posts: 2,178
Received 24 Likes on 13 Posts
mutt,

I have been told there was little change made to the brakes on the 737NG vs the 737OG, with a new wing, requireing higher V speeds, and higher weights, what did Boeing do to reduce the distances ?

I know of an airport that had its runway extended to cater for the 737NG, where the 737OG and A320's operated to previously.

Do different ICAO states have different requirments for selecting the TODR, ADSA etc ?

Do the winglets (if installed) on a 737NG have any effect on TODR apart from increasing the operating/basic weight of the aircraft ?

swh is offline  
Old 17th Aug 2004, 17:29
  #19 (permalink)  
 
Join Date: Dec 2003
Location: Dubai
Posts: 212
Likes: 0
Received 0 Likes on 0 Posts
Mutt,

Indeed you are right, the comparison btw 737 and 767 using the WAT or second segment would be contaminated by the drag of the engine that is at idle or shut down.

All engines perfo on t/o go is a better way to compare the real perfo.

Thanks, interesting and stimulating discussion
Cap 56 is offline  
Old 17th Aug 2004, 19:08
  #20 (permalink)  
 
Join Date: Sep 1999
Location: ME
Posts: 5,502
Likes: 0
Received 0 Likes on 0 Posts
swh,

Hang a smaller engine on the -700 and the 5200 ft turns into 8000 ft.

As for the winglets, check out http://www.aviationpartnersboeing.com

Mutt.
mutt is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.