Jet Engine Out Bank Angle
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Thanks for the clarification.
While not having had the military pilot exposure personally, other military involvements from time to time certainly have indicated some strange ideas in the QFI fraternity.
While not having had the military pilot exposure personally, other military involvements from time to time certainly have indicated some strange ideas in the QFI fraternity.
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FAR 23/25, model aircraft, whatever .. all same same
The flight test guide does permit up to 5 degrees bank angle for use during performance testing, which reduces the rudder angle required to keep the aircraft straight, thereby reducing drag in the OEI situation, generally speaking.
However, the performance benefit is certainly variable according to the aircraft's aerodynamic configuration, i.e. if the aircraft is equipped with spoilers for lateral control, some aircraft may, or may not gain a performance advantage with 5 degrees of bank, depending on control wheel deadband angle characteristics when out of center.
The aero guys will fine tune control wheel deadband during flight test according to the actual characteristics desired, before freezing the production configuration. Pilot Induced Oscillation (PIO) sometimes becomes an issue here.
This may explain why the 777 calls for zero bank on climb out with OEI (doubtless helped by the aircraft's relatively high power to weight ratio compared with older designs).
Last edited by twochai; 26th Feb 2017 at 15:22.
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The flight test guide does permit up to 5 degrees bank angle for use during performance testing
I think we need to isolate the Vmc handling and optimum climb situations for the benefit of those coming up the training pipeline. There is a great deal of misinformation and ignorance in the GA fraternity, especially.
if the aircraft is equipped with spoilers
Of course OEM AFM guidance is observed. However, unless spoiler operation commences with a very small wheel deflection, this won't necessarily be a problem. In any case, as zzuf observes, swept wing often favours something in the region of wheel level. If I recall from my Boeing days, spoilers came in at around 10 degrees wheel deflection ?
I'll leave the finer detail explanations to the certification TPs on the site, such as zzuf. (I am presuming you have a TP background but your profile provides no guidance as to what your specific background might be ? If my guess be correct, you may well know zzuf).
I think we need to isolate the Vmc handling and optimum climb situations for the benefit of those coming up the training pipeline. There is a great deal of misinformation and ignorance in the GA fraternity, especially.
if the aircraft is equipped with spoilers
Of course OEM AFM guidance is observed. However, unless spoiler operation commences with a very small wheel deflection, this won't necessarily be a problem. In any case, as zzuf observes, swept wing often favours something in the region of wheel level. If I recall from my Boeing days, spoilers came in at around 10 degrees wheel deflection ?
I'll leave the finer detail explanations to the certification TPs on the site, such as zzuf. (I am presuming you have a TP background but your profile provides no guidance as to what your specific background might be ? If my guess be correct, you may well know zzuf).
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when designing EO RNP procedures, turns are limited to 5° bank angle.
Can you cite a relevant document/Standard for perusal, please ? 5 degree bank would be very difficult to sign off on due to
(a) piloting difficulty unless it be autoflight
(b) the huge turn radius and flight path wind sensitivity for skirting nasty obstacles ...
15 degree turns are the norm for EO escape path planning. Generally one would only call up lesser bank in the case of an awkward obstacle on the inside of the turn .. and then only with a positive fix co-ordinate to commence the turn.
All these matters can be addressed with modern nav system capability .. but that infers considerable planning behind the procedure.
Can you cite a relevant document/Standard for perusal, please ? 5 degree bank would be very difficult to sign off on due to
(a) piloting difficulty unless it be autoflight
(b) the huge turn radius and flight path wind sensitivity for skirting nasty obstacles ...
15 degree turns are the norm for EO escape path planning. Generally one would only call up lesser bank in the case of an awkward obstacle on the inside of the turn .. and then only with a positive fix co-ordinate to commence the turn.
All these matters can be addressed with modern nav system capability .. but that infers considerable planning behind the procedure.
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john_tullamarine #2.
Please see appendix 5 of G-APFK_Append.pdf.
Full report: 1978_G-APFK.pdf
Achieved Vmc is very bank angle dependent.
Full report: 1978_G-APFK.pdf
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Full report
This report is cited from time to time in PPRuNe discussions on this sort of subject .. indeed, I used its content in briefing sessions in a past life.
Recommended reading for all young would-be heavy aircraft pilot folks ...
This report is cited from time to time in PPRuNe discussions on this sort of subject .. indeed, I used its content in briefing sessions in a past life.
Recommended reading for all young would-be heavy aircraft pilot folks ...
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undefire
Really?
when designing EO RNP procedures, turns are limited to 5° bank angle.
TERPS: These criteria are predicated on normal aircraft operations for considering obstacle clearance requirements. Normal aircraft operation means all aircraft systems are functioning normally
PANSOPS: 1.1.2 Procedures contained in PANS-OPS assume that all engines are operating. Note.— Development of contingency procedures is the responsibility of the operator.
What is your reference for designing EO RNP procedures?
Vmc is not really bank angle dependent.
Any manufacturer which chooses to use less than 5 degrees of bank, and any certification authority which will not accept 5 degrees of bank at Vmc are not using the certification standards as envisaged by the authors.
Vmc is simply a well defined certification speed.
Nobody has mentioned if the AFM Vmc has been determined as a static Vmc or dynamic Vmc. How would you know?
Some posters here probably would be astounded at the minimum speed which can be safely reached using no rudder and only bank to control yaw in an engine inoperative situation - assuming stalling is not a problem.
It can be safe to fly many aircraft around, one engine inoperative, take-off power on the other, at speeds well below Vmc. The speed reached in these circumstances is not Vmc - that speed has already been defined during certification.
It is simply a defined certification speed, for the reason of hanging oeio performance standards together.
It has nothing to do with the "loss of control speed".
If you are flying at around Vmc and are thinking you may lose control, not about to stall, roll on more bank, could be better than the alternative!
Any manufacturer which chooses to use less than 5 degrees of bank, and any certification authority which will not accept 5 degrees of bank at Vmc are not using the certification standards as envisaged by the authors.
Vmc is simply a well defined certification speed.
Nobody has mentioned if the AFM Vmc has been determined as a static Vmc or dynamic Vmc. How would you know?
Some posters here probably would be astounded at the minimum speed which can be safely reached using no rudder and only bank to control yaw in an engine inoperative situation - assuming stalling is not a problem.
It can be safe to fly many aircraft around, one engine inoperative, take-off power on the other, at speeds well below Vmc. The speed reached in these circumstances is not Vmc - that speed has already been defined during certification.
It is simply a defined certification speed, for the reason of hanging oeio performance standards together.
It has nothing to do with the "loss of control speed".
If you are flying at around Vmc and are thinking you may lose control, not about to stall, roll on more bank, could be better than the alternative!
Last edited by zzuf; 27th Feb 2017 at 13:17. Reason: typo
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I'm no knowledge expert but if my memory serves the RNP procedures are designed with up to 50kt adverse wind. Certainly the approaches are, not sure about the departures. That could explain the 5 degree bank restriction. In maximum adverse wind, in reality, that bank will increase, obviously.
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Vmc is not really bank angle dependent.
Indeed. However, this relates to the certification book Vmc speed.
Operational discussions out in the marketplace on bank and low speed directional control problems need to distinguish between the
(a) AFM Vmc book value (ie the certification animal which is well defined but of little precise value to the GA pilot in the street) and
(b) the rubbery low speed OEI directional control problems in the real world on the day which are sensitive to whatever bank is applied ... we use the term "Vmc" rather loosely and imprecisely in this latter case.
His comment regarding using a tad more bank is a key to delaying a departure early in the low speed OEI recovery.
Indeed. However, this relates to the certification book Vmc speed.
Operational discussions out in the marketplace on bank and low speed directional control problems need to distinguish between the
(a) AFM Vmc book value (ie the certification animal which is well defined but of little precise value to the GA pilot in the street) and
(b) the rubbery low speed OEI directional control problems in the real world on the day which are sensitive to whatever bank is applied ... we use the term "Vmc" rather loosely and imprecisely in this latter case.
His comment regarding using a tad more bank is a key to delaying a departure early in the low speed OEI recovery.
Re-reading my previous post, it could give the impression of a cavalier attitude to Vmc.
Vmc determination can be one of the most hazardous certification test procedures, with a high risk of departure at low altitude.
Work up should be done in, preferably, the engineering simulator. Plenty of departure recovery training, with PNF or flight test engineer responsible for rapidly closing the throttle of the operating engine as necessary.
In-flight work-up at a safe altitude. Don't do the low altitude tests until the test team are totally confident that a departure won't occur.
During these work-up test you will surely see speeds below what ends up being Vmc.
If the certification authority will accept some analysis in lieu of the really hazardous low altitude tests, grab the opportunity.
Vmc determination can be one of the most hazardous certification test procedures, with a high risk of departure at low altitude.
Work up should be done in, preferably, the engineering simulator. Plenty of departure recovery training, with PNF or flight test engineer responsible for rapidly closing the throttle of the operating engine as necessary.
In-flight work-up at a safe altitude. Don't do the low altitude tests until the test team are totally confident that a departure won't occur.
During these work-up test you will surely see speeds below what ends up being Vmc.
If the certification authority will accept some analysis in lieu of the really hazardous low altitude tests, grab the opportunity.
