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BECMG
24th Oct 2008, 12:52
What are the factors that affect the rotaion rate on Jet aeroplanes? Im aware that tail strike and consequently the length of the aircraft affects it but if you are flying the same aircraft everyday what things do you keep in mind during rotation? Can you guys list what the rotation rate is for your type of aircraft ?

Thanx and Regards.

Phil Squares
24th Oct 2008, 12:59
Just about every Boeing/Airbus/MCD I've flown recommends a rotation rate of 3 degrees/second. With a proper rotation rate you should be at V2-V2+10 when you are in the air.

RSFTO
24th Oct 2008, 13:03
on B747 is 2 degrees per second.

BelArgUSA
24th Oct 2008, 13:47
From 747 FCTM -
xxx
For optimum takeoff and initial climb performance, initiate a smooth continuous rotation between 2 to 3/second at VR to the rotation attitude. At light gross weights, the airplane accelerates rapidly and the rotation rate will be faster than at heavy gross weights.
xxx
The total time to rotate from VR to the rotation attitude will take 6 seconds with all engines operating, and 9 seconds for 3 engines operating.
xxx
Aft fuselage contact ("tail strike") on all 747 (except SP) will occur at 12.5 of pitch attitude with the wheels on runway and gear struts fully extended. Using flaps 20 rather than flaps 10 for takeoff reduces risk of tail strikes.
xxx
:)
Happy contrails

Rainboe
24th Oct 2008, 14:05
747 pilots are aware of the small ground clearance on lift off. At that moment, clearance is minimal, and can be as low as an incredible 18''. Therefore, correct rotation rates must be used to prevent too high an attitude before lift off, and in the engine failure case, very slightly slower rotation to a reduced attitude target. The later -400 had a printer that would print out after take-off unsatisfactory rotation technique! One dreaded hearing the printer spring into life!

Whilst the loadsheet would give the tail trim setting for take-off to give a standard rotation 'feel' to the elevator, one had to be prepared for the position of the C of G being fore or aft and changing the amount of force needed to rotate. It could make a significant difference and either make rotation too heavy, or too light and causing over rotation. Remember at the same time you may have a strong crosswind to contend with!

AI101
24th Oct 2008, 14:22
on a 737 =-800 the rate is 2-3 degrees per second , but using flaps 5 instead of 1 reduces the risk of having a tail strike.

BelArgUSA
24th Oct 2008, 14:27
And for the DC8... hope I remember all the details.
xxx
There were the "short DC8" and the "stretched DC8" (the 61/63 and 71/73)...
With the short DC8, rotation was "normal"... some 10-12 or so initially.
But for the stretched DC8, it was a rotation in "2 steps"...
The first step was to rotate to 8... wait the "feel" of being airborne.
Then, second step, continue rotation to the usual 12 or so...
xxx
SOP for PNF was to call "ROTATE LONG BODY" on T/O in a stretched DC8.
There was a "white dot" located 8 above horizon line on ADI for the stretched DC8.
That was your target attitude for the initial rotation step.
Many stretched DC8 pilots had a tail strike on their record.
I can proudly say that I remained a virgin...
xxx
:D
Happy contrails

Rainboe
24th Oct 2008, 14:43
One is intrigued how the 737-900 copes given that the 737-400 had frequent tailstrikes. Also the 757-300 looks a bit long and unwieldy. The 747 could not handle a further stretch with that fuselage design.

I once watched an Eastern A300 landing tailstrike at MIA close up (right next to it). Quite spectacular for a minor event, not even felt on the flight deck.

Capt Apache
24th Oct 2008, 16:45
Well explained.Good reading.Check it out.

http://www.copac.es/direcciones/Seguridad/AIRBUS%20FLIGHT%20OPERATIONS%20BRIEFING%20NOTES/24.FOBN.%20Takeoff%20and%20departure%20operations.%20Prevent ing%20tailstrike%20at%20takeoff.pdf

Cheers !

411A
24th Oct 2008, 16:47
Now, if we look further back in time, we come to the old B707-320 straight-pipe (non-fan, for you new folks) airplane.
At very heavy weights (and yes, this was the first heavy jet), if an engine (especially an outboard engine) failed just as the rotation maneuver began, one had better be very careful with the continued rate.
Large heading changes with that failed engine were a distinct possibility, as the rudder required an almighty push (nearly 150 pounds worth) to keep the airplane reasonably straight.

And no, I'm not so old that I flew these airplanes when they were new, but instead had been passed on down to ad-hoc charter carriers, after they had been worn down to very tired machines...ex-PanAmerican and TWA airplanes, mostly.

The result...pilots normally did a quite slow rotation at heavy weights, to be absolutely sure that the swing toward the failed engine could be countered, as the performance with these very early Boeings needed to be seen to be believed.

DP Davies was absolutely right to have challanged Boeing to modify the 707 rudder hydraulic power system...and for good reason.:ooh:

Flying old TriStars today, at heavy weights, the same slow rotation is used.
When First Officers ask why, I tell 'em...you gotta keep it straight if a wing engine fails.
In addition, if a rapid rotation with these tired old airplanes was tried at heavy weights, and an engine fails at the most critical time, you could find yourself at V2...and then watch the airspeed start to unwind.
This is not good, as then your climb rate (if you manage to have any left) goes straight downhill.
In these cases, a little extra speed is your friend.

Now I would expect that some of the new(er) pilots here might have a doubt about all this, with the newer generation of airplanes, but these are the facts with the old large heavy first generation jet transport airplanes.
Especially, the B707.

millerscourt
24th Oct 2008, 17:06
411A Not being as old as you I can only say the B707-320C with fans was the same. I seem to remember take off weights around 150 tons being the max.

Also unlike you I moved on from first generation heavy jets:{

BelArgUSA
24th Oct 2008, 17:26
I flew both the 707s.and the DC8s.
Includes the early 707-320 with JT-4, and the later DC8-60/70s types.
As far as pitch control "muscles", they required about the same.
Rudder, your legs needed about the same effort... a lot of muscles.
The big difference was the ailerons. Took twice as much muscle with DC8s.
The nicest flying DC8 was the DC8-62...
I liked the DC8-73... but just because of the CFM engine power.
Yet, I missed the 707-320B/C when I went to the DC8s.
Gross weight of the 707-320C was 334,000 lbs MTOW (sorry, I had pounds).
The DC8-63/73s grossed at 355,000 lbs MTOW.
xxx
:ok:
Happy contrails

Plain Driver
24th Oct 2008, 17:50
From:
Well explained.Good reading.Check it out.

http://www.copac.es/direcciones/Segu...%20takeoff.pdf (http://www.copac.es/direcciones/Seguridad/AIRBUS%20FLIGHT%20OPERATIONS%20BRIEFING%20NOTES/24.FOBN.%20Takeoff%20and%20departure%20operations.%20Prevent ing%20tailstrike%20at%20takeoff.pdf)

Cheers !

Statistical Data
About 25% of reported tailstrikes occur at takeoff and 65% at landing (Source: Airbus-2004).

Can't help it.....:confused: The remaining 10% is when....?
Cruise? Does being hit by a highloader count as a tailstrike?
Aft CG Loading..... that must be it!!!
I'll shush now....
PD

Capt. Inop
24th Oct 2008, 19:52
Can't help it..... The remaining 10% is when....?

http://farm3.static.flickr.com/2004/2187988624_3b3d114a78.jpg?v=0 :ok:

ad-astra
24th Oct 2008, 21:41
Those Yanks are certainly not afraid of trying new short field take-off procedures! :E

james ozzie
24th Oct 2008, 22:27
Pardon the dumb question but how do you know what your rotation rate is?

If you time the rotation and divide by the angle, yes, that gives an answer, but it is after the fact. Or is it gauged by feel / experience, as we do with the little planes? If so, how can it be so precise?

(Oh yes, a wise man once said to me: " A stupid question now can prevent a stupid mistake later..")

Reimers
24th Oct 2008, 22:58
Pardon the dumb question but how do you know what your rotation rate is?

The first couple of rotations are trained in the SIM, so if you don't get it right the first time, the instructor can tell you so before it gets expensive.

Rainboe
24th Oct 2008, 23:45
Ozzie, you begin to count when you lift the nosewheel off.....'and one and two and three and four and.........er five' by which time you should be through 10 degrees attitude where the rotation stops of its own accord, so you have to try and judge it to drag it a bit more up to 13-17 degrees, sometimes 20 if you are light. Once you get used to the rate, you don't need to count. There's a lot going on just then, the crosswind is then swinging the plane around, you're calling gear up and trying to nail the right speed.

Capt Chambo
25th Oct 2008, 00:05
"One is intrigued how the 737-900 copes given that the 737-400 had frequent tailstrikes."
The undercarraige is a little taller which helps. We have a placard in the flight deck reminding us of the pitch attitudes that will cause a tailstrike on both takeoff and landing. We are also "encouraged" to use the HUD for take-off as it has a tailstrike limit symbol.
It gets worse, as we sometimes have to do Flap1 takeoffs, that's when you really make sure you keep the rotation rate at 3 degrees per sec!
Funnily enough we have yet to have a tailstrike :)

stilton
25th Oct 2008, 07:39
On the 757-300 the tail hits at a little over 8 degrees. However the v speeds are pushed up considerably to account for this, so in reality you have plenty of clearance.

Actually makes for a nicer flying aircraft I think, seems more stable on the approach and the longer body seems to flex more in turbulence giving a smoother ride.