Define Vfe
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Maximum Flap Extension/Extended Speed - (several values depending on aircraft type and the position of extension) -do not extend or operate with flaps in prescribed position above these speeds.
If the aircraft has a different Vfe for different flap settings, then obey those individually. If it only has one, common sense dictates that flaps must be UP above this speed, and can be lowered below it. While small flap settings probably put less stress on it, just be smart and make sure that no flaps are down above Vfe
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Indeed
e.g. A PA34-200T Seneca2 has a flight manual stated VFE of 107kts although 10degrees can be put down at 138kts and 25degrees put down at 121kts. The full 40 can be extended in the white arc (below 107kts).
Maybe this changes for different aircraft, but I assume that VFE is for full flap extension.
e.g. A PA34-200T Seneca2 has a flight manual stated VFE of 107kts although 10degrees can be put down at 138kts and 25degrees put down at 121kts. The full 40 can be extended in the white arc (below 107kts).
Maybe this changes for different aircraft, but I assume that VFE is for full flap extension.
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Some 172's have high speed flaps. From memory first stage (10deg?) can be taken at 110kts which is well above top of white arc.
I think similar applies in the 206 too. Once again, from memory 10deg at 140kts (i think top of Vno was 150kts).
But consult the manual (don't assume it will be the same for all a/c), it will reveal all.
Knox.
I think similar applies in the 206 too. Once again, from memory 10deg at 140kts (i think top of Vno was 150kts).
But consult the manual (don't assume it will be the same for all a/c), it will reveal all.
Knox.
Last edited by knox; 12th Sep 2008 at 11:50.
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I had always understood it was no flap down above the white arc however different people have told me otherwise that it is ok to put 10 deg out above white arc to help slow ac down and others have said vfe is for full flap.
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solowflyer... read your flight manual. Dont take anyones word.
As i recall i think some cessnas... 172,182 you can take the first 10 degrees above the white arc, but below the specified airspeed in the flight manual
Also regarding post #1. You refer to Vfe as flap extension speed, which is technically wrong. Vfe is flap EXTENDED speed.
Flap extension speed is refered to as Vfo or flap operating speed (as the flap comes down)
As i recall i think some cessnas... 172,182 you can take the first 10 degrees above the white arc, but below the specified airspeed in the flight manual
Also regarding post #1. You refer to Vfe as flap extension speed, which is technically wrong. Vfe is flap EXTENDED speed.
Flap extension speed is refered to as Vfo or flap operating speed (as the flap comes down)
Different manufacturers....
It's all about semantics, but the different manufacturers are talking the same thing.
I currently fly two very different transport cat aircraft types -
Type 1:
Vfe = "Maximum Flap Extended Speed or Operating Speed"
Flap 2 (15deg)=200kts, Flap 3 (20deg)=185kts, Flap full (40deg) =177kts.
Type 2:
Flap Extended Speeds
The maximum permissible airspeeds for extending the wing flaps and for flight with the flaps extended
(VFE) are:
To/App (10deg)- 135kts, ldg (40deg) 115kts.
The common theme is that it's the maximum speed at which you can extend them or accelerate to with them already extended.
C210 drivers beware - different models have different flap speeds. From memory N series had a flap speed of 156 kts for the first stage. I never found out what the physical difference was compared to earlier models.
I currently fly two very different transport cat aircraft types -
Type 1:
Vfe = "Maximum Flap Extended Speed or Operating Speed"
Flap 2 (15deg)=200kts, Flap 3 (20deg)=185kts, Flap full (40deg) =177kts.
Type 2:
Flap Extended Speeds
The maximum permissible airspeeds for extending the wing flaps and for flight with the flaps extended
(VFE) are:
To/App (10deg)- 135kts, ldg (40deg) 115kts.
The common theme is that it's the maximum speed at which you can extend them or accelerate to with them already extended.
C210 drivers beware - different models have different flap speeds. From memory N series had a flap speed of 156 kts for the first stage. I never found out what the physical difference was compared to earlier models.
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Extend - Retract - Exceed
Exactly - it still seems some manage get their VFE approach and full down semantics mixed up with the VLO (extension and retraction) and VLE (extended).
Don't hold your breath Knox - it could be a while - brns2 has gone off to do some reading.
Don't hold your breath Knox - it could be a while - brns2 has gone off to do some reading.
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Far out you get shot down in here very quickly
Well i had a look in a beechcraft manual and their definition for Vfe is:
"Maximum flap EXTENDED speed is the highest speed permissible with wing flaps in a prescribed EXTENDED position"
So to me this means its a limit when they are in their extended position, not as you are putting them down in the transition. To me that is a operating speed referenced as Vfo. The beechcraft manual doesnt have Vfo (maybe it doesnt require it as it cant cause structural damage if the Vfe speed is complied with?)
I could not find a referance in any manual to Vfo, so i did a search for "Vfo airspeed limitaions" on the www and came accross the same definitions as i suggested. Heres one page i found on V speeds:
V1 | Take-off decision speed
V2 | Take-off safety speed (minimum)
Va | Design maneuvering speed
Vb | Design speed for maximum gust
Vc | Design Cruising speed
Vd | Design Diving speed
Vdf/Mdf | Demonstrated Flight diving speed
Vf | Design Flap speed
Vfc/Mfc | Maximum speed for stability Characteristics
Vfe | Maximum Flap Extended speed
Vfo | Maximum Flap Operating speed
Vh | Maximum speed in level flight with maximum continuous power
Vle | Maximum Landing gear Extended speed
Vlo | Maximum Landing gear Operating speed
Vlof | Liftoff speed
Vmc | Minimum Control speed
Vmca | Air Minimum Control speed
Vmcg | Ground Minimum Control speed
Vmo/Mmo | Mach, Maximum Operating limit speed
Vmu | Minimum Unstick speed (liftoff)
Vne | Never Exceed speed
Vno | Maximum structural cruising speed
Vpw | Pilot Window open speed
Vr | Rotation speed
Vref | Reference speed
Vs | Stalling speed
Vs1 | Stalling speed in a specified configuration
Vso | Stalling speed in the landing configuration
Vsse | Safe Single-Engine speed (render an engine inop)
Vtos | Take-Off Safety speed
Vtoss | Take-Off Safety speed category "A" rotorcraft
Vww | Windshield Wiper operating speed
Vx | Best angle of climb speed
Vxse | Best angle of climb speed, Single Engine
Vy | Best rate of climb speed
Vyse | Best rate of climb speed, Single Engine
Well i had a look in a beechcraft manual and their definition for Vfe is:
"Maximum flap EXTENDED speed is the highest speed permissible with wing flaps in a prescribed EXTENDED position"
So to me this means its a limit when they are in their extended position, not as you are putting them down in the transition. To me that is a operating speed referenced as Vfo. The beechcraft manual doesnt have Vfo (maybe it doesnt require it as it cant cause structural damage if the Vfe speed is complied with?)
I could not find a referance in any manual to Vfo, so i did a search for "Vfo airspeed limitaions" on the www and came accross the same definitions as i suggested. Heres one page i found on V speeds:
V1 | Take-off decision speed
V2 | Take-off safety speed (minimum)
Va | Design maneuvering speed
Vb | Design speed for maximum gust
Vc | Design Cruising speed
Vd | Design Diving speed
Vdf/Mdf | Demonstrated Flight diving speed
Vf | Design Flap speed
Vfc/Mfc | Maximum speed for stability Characteristics
Vfe | Maximum Flap Extended speed
Vfo | Maximum Flap Operating speed
Vh | Maximum speed in level flight with maximum continuous power
Vle | Maximum Landing gear Extended speed
Vlo | Maximum Landing gear Operating speed
Vlof | Liftoff speed
Vmc | Minimum Control speed
Vmca | Air Minimum Control speed
Vmcg | Ground Minimum Control speed
Vmo/Mmo | Mach, Maximum Operating limit speed
Vmu | Minimum Unstick speed (liftoff)
Vne | Never Exceed speed
Vno | Maximum structural cruising speed
Vpw | Pilot Window open speed
Vr | Rotation speed
Vref | Reference speed
Vs | Stalling speed
Vs1 | Stalling speed in a specified configuration
Vso | Stalling speed in the landing configuration
Vsse | Safe Single-Engine speed (render an engine inop)
Vtos | Take-Off Safety speed
Vtoss | Take-Off Safety speed category "A" rotorcraft
Vww | Windshield Wiper operating speed
Vx | Best angle of climb speed
Vxse | Best angle of climb speed, Single Engine
Vy | Best rate of climb speed
Vyse | Best rate of climb speed, Single Engine
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No bullets intended brns2 - only shooting blanks these days anyway
Interesting table of Veees - and to think all this time I was trying to reach a V TOSS when really it was a V TOS
Interesting table of Veees - and to think all this time I was trying to reach a V TOSS when really it was a V TOS
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Well maybe i am wrong and so are the others that differ between Vfe and Vfo.
But do you not differ between a Vlo and a Vle?
Beechcraft manual specificaly says Vfe is an EXTENDED speed limit
Disregarding any manual, and just thinkingn about it with some commonsense, possibly some aircrafts design are so the flaps are not as strong in the transition as they are in their extended positions, these are the ones that have a Vfo stated?
But do you not differ between a Vlo and a Vle?
Beechcraft manual specificaly says Vfe is an EXTENDED speed limit
Disregarding any manual, and just thinkingn about it with some commonsense, possibly some aircrafts design are so the flaps are not as strong in the transition as they are in their extended positions, these are the ones that have a Vfo stated?
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Its different for different aircraft and its usually placarded beside the lever. i see a few references to 172s there. That depends on the model. The 172P can take 10 degrees at 110kts, the rest in the white arc. The piper archer by comparison you arent permitted to put any flap down until in the white arc. The 210 is model dependent too. In my L model i can take 10 degrees at 140kts, and throw the wheels out then too, but no more flap til the white arc, but in later models such as the M and N, you can throw out 10 flap and wheels at 165, at the top of the green arc.
So there is no hard and fast answer for all a/c types. As someone says, read the Flight Manual, its all in there. Most likely in the most illogical place in the flight manual imaginable if its a cessna one
So there is no hard and fast answer for all a/c types. As someone says, read the Flight Manual, its all in there. Most likely in the most illogical place in the flight manual imaginable if its a cessna one
I don't understand what the problem is really. If the flight manual says you can lower X flaps at Y speed, then you can do that. If it isn't in the flight manual, then don't do it!
Lowering flaps outside the Flight Manual prescribed Vfe for that flap setting is a no no. If someone needs to bust flap limits to slow down, that probably says more about their speed control than anything else.
It's like saying "I just want to get there a bit faster, so I'll fly a little above Vne." It isn't done.
The only time you can lower flaps outside the white arc is when the particular aircraft has down a different Vfe for 10deg flaps. For example, a Duchess can lower (from memory) up to 20deg of flaps, at a speed higher than on the white arc, but that flap setting still has a limiting speed placed on it, it just happens to be slightly higher than the white arc, which is the limiting speed for >20deg flaps.
If the flight manual only gives ONE flap extension speed, then above this speed no flap is to be extended. If the flight manual gives different speeds for first stage and other flap, then extend no flaps above highest speed, only extend first stage below first stage speed, second stage below its prescribed speed etc.
brns2 et al: If you think about it another way, as soon as the flaps leave the full up position, they are extended in someway, even if they are also in transit.
I had always understood it was no flap down above the white arc however different people have told me otherwise that it is ok to put 10 deg out above white arc to help slow ac down and others have said vfe is for full flap.
It's like saying "I just want to get there a bit faster, so I'll fly a little above Vne." It isn't done.
The only time you can lower flaps outside the white arc is when the particular aircraft has down a different Vfe for 10deg flaps. For example, a Duchess can lower (from memory) up to 20deg of flaps, at a speed higher than on the white arc, but that flap setting still has a limiting speed placed on it, it just happens to be slightly higher than the white arc, which is the limiting speed for >20deg flaps.
If the flight manual only gives ONE flap extension speed, then above this speed no flap is to be extended. If the flight manual gives different speeds for first stage and other flap, then extend no flaps above highest speed, only extend first stage below first stage speed, second stage below its prescribed speed etc.
brns2 et al: If you think about it another way, as soon as the flaps leave the full up position, they are extended in someway, even if they are also in transit.
Last edited by Cap'n Arrr; 13th Sep 2008 at 00:45.
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Muffinman, tis the trouble with finding information on the net, no such thing as Vtos, stick with the Vtoss 
The FAA definitions follow
V A design maneuvering speed
V B design speed for maximum gust intensity
V C design cruising speed
V D design diving speed
V DF/ M DF demonstrated flight diving speed
V EF the speed at which the critical engine is assumed to fail during takeoff
V F design flap speed
V FC/ M FC maximum speed for stability characteristics
V FE maximum flap extended speed
V FTO final takeoff speed
V H maximum speed in level flight with maximum continuous power
V LE maximum landing gear extended speed
V LO maximum landing gear operating speed
V LOF lift-off speed
V MC minimum control speed with the critical engine inoperative
V MO/ M MO maximum operating limit speed
V MU minimum unstick speed
V NE never-exceed speed
V NO maximum structural cruising speed
V R rotation speed
V REF reference landing speed
V S the stalling speed or the minimum steady flight speed at which the airplane is controllable
V S0 the stalling speed or the minimum steady flight speed in the landing configuration
V S1 the stalling speed or the minimum steady flight speed obtained in a specific configuration
V SR reference stall speed
V SRO reference stall speed in the landing configuration
V SR1 reference stall speed in a specific configuration
V SW speed at which onset of natural or artificial stall warning occurs
VTOSS takeoff safety speed for Category A rotorcraft
V X speed for best angle of climb
V Y speed for best rate of climb
V 1 the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance. V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance
V 2 takeoff safety speed
V 2min minimum takeoff safety speed
It's interesting that in the regs (design criteria for Part 23 and 25 aircraft) there is no such thing as Vfo mentioned. Only Vf and Vfe. Where does this Vfo get mentioned? Flight manual?
To airaholic, the official FAA definition of Vfe is maximum flap extended speed, and the answer to "can partial flap be extended above vfe?" the answer is a resounding NO. Follow your particular flight manual. The Vfe may vary depending on the amount of flap - Chieftain for example, 162 kias up to 25° of flap, then 132 kias to 40°
The FAA definitions followV A design maneuvering speed
V B design speed for maximum gust intensity
V C design cruising speed
V D design diving speed
V DF/ M DF demonstrated flight diving speed
V EF the speed at which the critical engine is assumed to fail during takeoff
V F design flap speed
V FC/ M FC maximum speed for stability characteristics
V FE maximum flap extended speed
V FTO final takeoff speed
V H maximum speed in level flight with maximum continuous power
V LE maximum landing gear extended speed
V LO maximum landing gear operating speed
V LOF lift-off speed
V MC minimum control speed with the critical engine inoperative
V MO/ M MO maximum operating limit speed
V MU minimum unstick speed
V NE never-exceed speed
V NO maximum structural cruising speed
V R rotation speed
V REF reference landing speed
V S the stalling speed or the minimum steady flight speed at which the airplane is controllable
V S0 the stalling speed or the minimum steady flight speed in the landing configuration
V S1 the stalling speed or the minimum steady flight speed obtained in a specific configuration
V SR reference stall speed
V SRO reference stall speed in the landing configuration
V SR1 reference stall speed in a specific configuration
V SW speed at which onset of natural or artificial stall warning occurs
VTOSS takeoff safety speed for Category A rotorcraft
V X speed for best angle of climb
V Y speed for best rate of climb
V 1 the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance. V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance
V 2 takeoff safety speed
V 2min minimum takeoff safety speed
It's interesting that in the regs (design criteria for Part 23 and 25 aircraft) there is no such thing as Vfo mentioned. Only Vf and Vfe. Where does this Vfo get mentioned? Flight manual?
To airaholic, the official FAA definition of Vfe is maximum flap extended speed, and the answer to "can partial flap be extended above vfe?" the answer is a resounding NO. Follow your particular flight manual. The Vfe may vary depending on the amount of flap - Chieftain for example, 162 kias up to 25° of flap, then 132 kias to 40°