kurbitur
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Bigger Planes Use Shorter Rwy Than Smaller Ones?

Mon Jan 03, 2011 12:06 am

I was spotting today at Copenhagen Kastrup (CPH) and was close-up to the departing aircrafts at rwy 4 R.

I noticed SAS A321 and taxing to the 3rd exit to the beginning of the runway and 737-800

Than Continental 757 went for the second last taxiway into the runway with full throttle

Than some SAS Canadair CL-600 Regional Jets and Wideroe´s (De Havilland) went for the whole runway, with
nose gear almost licking the grass.

any guesses?




(took this one today of CO to EWR)
 
GIANCAVIA
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Mon Jan 03, 2011 12:09 am

Weight... some are fully loaded some arent.. some are better performing aircraft in certain weathers/elevations then others .. etc etc
 
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chrisnh
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Mon Jan 03, 2011 12:11 am

Just a guess on my part, but the bigger wing surface on a 'bigger plane' would also help lift it into the air sooner than a small wing surface.
 
kcrwflyer
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Mon Jan 03, 2011 12:19 am

That runway's almost 11,000ft. I'd imagine all of the entrances used gave the pilots at least 8,000? They're all probably just doing what's most convenient for them. ORD uses intersection departures on a daily basis.
 
GIANCAVIA
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Mon Jan 03, 2011 12:23 am

When Im at luton regularly you have the tiny citations or hawkers backtracking and using the whole runway and then a ryanair 738 or an ezy A319 will just taxi straight onto the runway and do a short take off.
 
rfields5421
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Mon Jan 03, 2011 12:30 am

It's a matter of power to weight ratio.

But it may also be a matter of airline operating policy. Some airlines require takeoff from the end of the runway and do not allow intersection takeoffs.

Bigger light planes with more power can takeoff faster with less runway than smaller heavy planes with less power which take more runway.

The CRJ-200 is well known for needing a lot of runway if full of pax, bags and fuel.

Bombardier's specs say the CRJ at MTOW needs

CRJ-200 ER - 5,800 ft
CRJ-200 LR - 6,290 ft

CRJ-700 701 - 5,130 ft
CRJ-700 701 ER - 5,500 ft
CRJ-700 701 LR - 6,072 ft

CRJ-700 705 - 5,833 ft
CRJ-700 705 ER - 6,105 ft
CRJ-700 705 LR - 6,378 ft

CRJ-900 - 5,833 ft
CRJ-900 ER - 6,105 ft
CRJ-900 LR - 6,379 ft

http://www.crj.bombardier.com/CRJ/en...sp?langId=en&crjId=200#performance
 
bluewhale18210
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Mon Jan 03, 2011 12:34 am

1. Full takeoff Vs. Flex takeoff. The Flex uses more runway at a lower N1 setting which conserves engine parts.
2. The bigger plane might be loaded at a lower percentage and therefore has more excess thrust for a early rotation.
3. This escapes lots of people...but depending on the design of the airplane, smaller planes might need more runway.
For example a 737 is an Approach Catagory C aircraft, the Vref being between 120-140kt. CRJ-200, despite being smaller and less than half the weight, is Catagory D, Vref 140-160kt for lack of leading edge devices. That also meant a CRJ2 needs more speed on takeoff as well. CRJ9 is back to being CAT C.
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BMI727
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Mon Jan 03, 2011 12:34 am

Quoting rfields5421 (Reply 5):
The CRJ-200 is well known for needing a lot of runway if full of pax, bags and fuel.

The lack of slats has a lot to do with that.

Quoting kurbitur (Thread starter):
any guesses?

It is a bit difficult to make any judgments just by watching, since probably almost all of those planes were using a derated takeoff to some degree.
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RussianJet
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Mon Jan 03, 2011 12:37 am

Quoting Kcrwflyer (Reply 3):
That runway's almost 11,000ft. I'd imagine all of the entrances used gave the pilots at least 8,000? They're all probably just doing what's most convenient for them. ORD uses intersection departures on a daily basis.

  

Although there are a ton of potential variables, the most likely common denominator here was whatever was easiest from a traffic and taxy distance perspective.
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dimik747
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Mon Jan 03, 2011 1:24 pm

Flex/Derated takeoffs aside there is nothing really connecting small planes to shorter take off rolls unless they are designed that way. For example you could add a ge-90 on a 737 or on a crj-200 and it would take off very quickly, but if STOL isnt the particular mission of the airplane there is not much point adding a bigger wing and more high lift devices (and therefore more weight) just so it can take off on a short roll. The crj-200 for example is a much smaller airplane, but it has no leading edge devices so it requires much higher speeds and it seems to be doing just fine
 
B777LRF
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Tue Jan 04, 2011 1:57 am

Quoting rfields5421 (Reply 5):
It's a matter of power to weight ratio.


That is certainly part of the equation, but as the BAe-146 will testify it's only half the answer. The other variable is of course lift.

To elaborate, it's the design of a wing that determines the speed at which enough lift is generated to get an aircraft off the ground; bigger engines will only help reach that speed faster. Hence an aircraft with a poor thrust-to-weight ratio and a high lift wing might very well get off the ground quicker than a much more powerful, but low lift, ditto; Super-Cub vs F-15 is an excellent example.
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airportugal310
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Wed Jan 05, 2011 2:48 am

I think some pilots just like the thought of having extra runway to play with...gives them more options or more runway to play with in some kind of emergency (whatever that may be).

Im sure human factors are involved in it, somehow

I would probably fall into that category, all ops specs aside
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goboeing
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Wed Jan 05, 2011 4:26 am

Quoting airportugal310 (Reply 11):
I think some pilots just like the thought of having extra runway to play with...gives them more options or more runway to play with in some kind of emergency (whatever that may be).

Im sure human factors are involved in it, somehow

I would probably fall into that category, all ops specs aside

Ohhh yeah.

One runway we sometimes use at an outstation absolutely has got to have something totally wrong in the performance data, because if we do a flaps 2 takeoff, the usual configuration in our airplane, we'll often pass over the departure end climbing through about 30 feet. With an engine failure at V1, we're supposed to be guaranteed 35' AGL by then. Absolutely no chance a rejected takeoff shortly before V1 would end in anything other than a runway overrun.

So, we do a longer taxi to the longer runway.
 
Goldenshield
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RE: Bigger Planes Use Shorter Rwy Than Smaller Ones?

Wed Jan 05, 2011 11:53 am

Quoting BLUEWHALE18210 (Reply 6):
For example a 737 is an Approach Catagory C aircraft, the Vref being between 120-140kt. CRJ-200, despite being smaller and less than half the weight, is Catagory D, Vref 140-160kt for lack of leading edge devices. That also meant a CRJ2 needs more speed on takeoff as well. CRJ9 is back to being CAT C.

The CR7 is Cat C, but the CR9 is back up to Cat D. I'm assuming that Bombardier did some improvements on the -1000 so that it's brought back down to C again.

However, the above has nothing to do with taking off, hence why they are called Approach Categories.
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