Kcrwflyer From United States of America, joined May 2004, 3711 posts, RR: 8 Reply 3, posted (2 years 11 months 3 weeks 1 day 7 hours ago) and read 4789 times:
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 From Vatican City, joined Feb 2010, 1291 posts, RR: 0 Reply 4, posted (2 years 11 months 3 weeks 1 day 7 hours ago) and read 4750 times:
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.
BLUEWHALE18210 From United States of America, joined Aug 2006, 237 posts, RR: 0 Reply 6, posted (2 years 11 months 3 weeks 1 day 7 hours ago) and read 4656 times:
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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RussianJet From Kyrgyzstan, joined Jul 2007, 7354 posts, RR: 23 Reply 8, posted (2 years 11 months 3 weeks 1 day 7 hours ago) and read 4633 times:
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 From Greece, joined Nov 2010, 51 posts, RR: 0 Reply 9, posted (2 years 11 months 3 weeks 18 hours ago) and read 2531 times:
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
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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GoBoeing From United States of America, joined Jun 2000, 2662 posts, RR: 15 Reply 12, posted (2 years 11 months 2 weeks 6 days 3 hours ago) and read 2010 times:
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
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.
Goldenshield From United States of America, joined Jan 2001, 5656 posts, RR: 15 Reply 13, posted (2 years 11 months 2 weeks 5 days 19 hours ago) and read 1941 times:
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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