Rolling vs static takeoffs
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Rolling vs static takeoffs
The new company I work for has a "policy" of doing static takeoffs for all takeoffs in the Citation 560 series. I dislike them for several reasons.
1. You sit on the runway for extra time fine tuning the power.
2. I can't imagine it is good for the airplane, sitting in position at high power sucking up who knows what, and the airplane feels like it is straining, ie vibrating and shaking, I know it is a jet but they still do.
3. The other part of the "policy" is that you release the brakes slowly, which I think defeats the purpose of static, ie minimize ground roll.
4. FO's have a hard time keeping it straight, until things are stabilized.
I realize the performance numbers are based on static TO's, but I would like to know if anybody has the actual numbers for this airplane, comparing the 2 takeoffs. Most of the runways have at least 50-75% more runway than is required. I would also take reccomendations for any other jet aircraft.
Thanks.
1. You sit on the runway for extra time fine tuning the power.
2. I can't imagine it is good for the airplane, sitting in position at high power sucking up who knows what, and the airplane feels like it is straining, ie vibrating and shaking, I know it is a jet but they still do.
3. The other part of the "policy" is that you release the brakes slowly, which I think defeats the purpose of static, ie minimize ground roll.
4. FO's have a hard time keeping it straight, until things are stabilized.
I realize the performance numbers are based on static TO's, but I would like to know if anybody has the actual numbers for this airplane, comparing the 2 takeoffs. Most of the runways have at least 50-75% more runway than is required. I would also take reccomendations for any other jet aircraft.
Thanks.
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I don't think it matters and I agree that rolling is better than static for the engines, I think a fair comprimise is to spool up to around 60% of full power then release; this should allow for fast engine acceleration without drag racing
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rhov
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rhov
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Some of the same concerns have been discussed at http://www.pprune.org/forums/showthread.php?t=9370
For my two-bobs worth, I would have thought that an exec jet would visit a variety of airports with a variety of maintenance standards and that a policy of static takeoffs would be likely to result in increased FOD.
For my two-bobs worth, I would have thought that an exec jet would visit a variety of airports with a variety of maintenance standards and that a policy of static takeoffs would be likely to result in increased FOD.
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WOW, OverRun!!! a great oldie you've found
I love the "archives [as I call'em] I think lots of folks are afraid to go back in Pprune more than a month prior 
Wise Men speaking
Props Before Throttle!!!, rhov
rhov
I love the "archives [as I call'em] I think lots of folks are afraid to go back in Pprune more than a month prior Wise Men speaking
Props Before Throttle!!!, rhov
rhov
In the C-5, we took a 250 foot "line-up" penalty and a 750 foot penalty for rolling take-offs, i.e. the assumption was 250 feet to line-up off the taxyway and an additional 750 feet was added for rolling take-offs. The line-up made sense, just because of the size the the plane, but I couldn't tell after 4000 hours what difference the rolling vs. standing take-off made. A rolling take-off always had the take-off N1 established within a 800-1000 feet and acceleration from the standing start wasn't knocking anybody's heads back.
BTW, in the French-Canadian built bizjets, the FMS computes a 100 foot line-up reduction in TORA. Seems fair to me.
GF
BTW, in the French-Canadian built bizjets, the FMS computes a 100 foot line-up reduction in TORA. Seems fair to me.
GF
Surely you need to fly the take-off as specified in the Flight Manual in order to achieve the scheduled performance?
When I was on the B737 variants I recall the Flight Manual said that a rolling take off was preferred OR a certain power setting (quite modest) set before brake release after which (obviously) set take off thrust.
When I was on the B737 variants I recall the Flight Manual said that a rolling take off was preferred OR a certain power setting (quite modest) set before brake release after which (obviously) set take off thrust.
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It would be tempting to say, "Built by French-Canadians, but financed by ALL Candadians", but that wouldn't be truthy either...built by Ontarians, Japanese, Chinese, Americans (think Learjet) and others, no doubt.
GF
GF
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There is only one type that I have flown that really did require that static thrust be (reasonably) set prior to brakes release, at very heavy weights, and that was the 'ole B707-300 series, with straight-pipe engines (JT4A's).
These engines took a loooong time to spool-up, both for takeoff thrust, and on the approach, if you got a tad too low.
Rolling takeoffs with these were OK however at lighter weights.
Even with static thrust set, at heavy weights, you got up close and personal with the far end if the runway.
These engines took a loooong time to spool-up, both for takeoff thrust, and on the approach, if you got a tad too low.
Rolling takeoffs with these were OK however at lighter weights.
Even with static thrust set, at heavy weights, you got up close and personal with the far end if the runway.
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I was flt ops engr covering an engine which occasionally displayed a "hangup" or interrupted accel on TO. We found it only happened during "zero bleed" TO's, and that turning on bleeds would clear the stall. So the recommended procedure was:
Leave bleeds on when taking the runway
Part throttle, watch for normal windup
Turn bleeds off for EGT/ITT margin
Push to normal TOGA setting
With a F/E onboard, All this could be done during a rolling TO without hassle.
Leave bleeds on when taking the runway
Part throttle, watch for normal windup
Turn bleeds off for EGT/ITT margin
Push to normal TOGA setting
With a F/E onboard, All this could be done during a rolling TO without hassle.
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Ahhh.....if only we still had FEs,
OK...back to the present, Boeing (B737NG) recommends that rolling takeoffs are better, less chance of compressor stalls due to crosswinds.
If the rolling takeoff is carried out correctly, there is no appreciable difference in t/o distance required.
That means, advancing the thrust to approximately 40% N1 to stabilize both engines, is limited to a maximum of 2 seconds at that setting, before TOGA is selected, otherwise takeoff performance may be affected.
Simple and easy,
Cheers, FD
OK...back to the present, Boeing (B737NG) recommends that rolling takeoffs are better, less chance of compressor stalls due to crosswinds.
If the rolling takeoff is carried out correctly, there is no appreciable difference in t/o distance required.
That means, advancing the thrust to approximately 40% N1 to stabilize both engines, is limited to a maximum of 2 seconds at that setting, before TOGA is selected, otherwise takeoff performance may be affected.
Simple and easy,
Cheers, FD
On the 737 series from -100 right through to the latest NG, the brakes are released before opening the throttles to stable N1 or EPR. It is not required to hold the brakes on while opening the thrust levers.
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... except in moderate to severe icing conditions, where - at least on classics - you must do a static runup at 70% N1 and observe stable engines operation before brakes release...
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Is there any difference with LVTO in the procedures on the 737 classics or NGs for that matter - standing take offs with 70% N1?? When do you then press the TOGA buttons, on brake release??
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N1 - 74%
N2 - 84%
EGT - 400 degrees
Fuel Flow - 4,000 PPH +/-
An indication of a failed surge bleed valve would be a higer EGT.
Once satisfied the breaks are released and away you go. This could be done on a rolling takeoff, provided thrust was set prior to 60 knots.
On the NG power is increased to 40% N1... look for stabilization of the motors and press TOGA. This can also be done performing a rolling takeoff, provided that takeoff thrust is set prior to 60 knots.
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70% on NG's for Severe Icing conditions which I think is the same for Classics.
Static t/o's can increase your brake temp with t/o power set. Possibly meaning any failure before v1 and you abandon the t/o roll could lead to you not having the braking capacity to stop.
That is what I have been told anyway. I personally would use static if you have to back track and do a 180. If no back track a rolling. Not my SOP's though.
Static t/o's can increase your brake temp with t/o power set. Possibly meaning any failure before v1 and you abandon the t/o roll could lead to you not having the braking capacity to stop.
That is what I have been told anyway. I personally would use static if you have to back track and do a 180. If no back track a rolling. Not my SOP's though.