Vle vs. Vlo

FlyboyZR1 · September 29th, 2004, 16:24

If an airplane has a Vle speed of 150mph, and a Vlo of 125mph, can the landing gear be extended above 125mph?

I always thought the gear could be extended below Vle, and that it can only be retracted below Vlo ... but the FAA Handbook says the gear can only be extended below Vlo.

gomntwins · September 29th, 2004, 16:37

[ QUOTE ]
If an airplane has a Vle speed of 150mph, and a Vlo of 125mph, can the landing gear be extended above 125mph?

I always thought the gear could be extended below Vle, and that it can only be retracted below Vlo ... but the FAA Handbook says the gear can only be extended below Vlo.

[/ QUOTE ]

Vle is the speed at which you can fly around with the gear down and locked into place. If you took off in an aircraft with a Vle speed of 150mph, that means you could, if the gear were extended and locked into place, fly up to a speed of 150mph safely. The maximum speed that you can extend the gear from the retracted position, however, is 125mph, or Vlo. Many aircraft have Vle and Vlo the same speed... but not all. One reason why the speeds may be different are the aerodymanic principals of the gear while in transit... within the speeds of 126 up to 150, in the case of the example given, the forces placed on the gear may be too much and could cause a threat. Or maybe at that speed, the gear may not come down because of the speed. However, if the gear is already locked into place by 125mph, you can safely reach a speed of 150 without having gear doors fly off, or worse.

USMCmech · September 29th, 2004, 16:40

MOst airplanes have a Vlo speed to keep the nose gear from slaming back into the gearwell too quickly. (most light airplanes)

However some others have gear doors or other pieces that move durring gear extension or retraction that can't handle the stress of a higher airspeed. (the B-707 comes to mind)

So Vlo applies for both extension and retraction.

Then you can speed up to Vle.

FlyboyZR1 · September 29th, 2004, 17:24

Thanks, got it.

kellwolf · September 29th, 2004, 18:48

[ QUOTE ]
If an airplane has a Vle speed of 150mph, and a Vlo of 125mph, can the landing gear be extended above 125mph?

[/ QUOTE ]

Hmmm, Seneca huh?

Think about the nosewheel and which direction it retracts. It would have to retract against the relative wind, and it's only safe to do so below 125 mph.

FlyboyZR1 · September 29th, 2004, 19:05

[ QUOTE ]

Hmmm, Seneca huh?

Think about the nosewheel and which direction it retracts. It would have to retract against the relative wind, and it's only safe to do so below 125 mph.

[/ QUOTE ]

Close ... it's an Arrow II.

moxiepilot · September 29th, 2004, 21:25

[ QUOTE ]

Think about the nosewheel and which direction it retracts. It would have to retract against the relative wind,

[/ QUOTE ]

Not only that, but gravity too. Gear doors are usually a limiting factor for speed, but gravity and wind can put too much strain on the torque tube or chain for the system to safely handle.

-mox

C650CPT · October 8th, 2004, 15:15

It has to do with the motor moving the gear, the aerodynamic forces working against the motor is the reason for the limit. Most gears can take the stress but to keep weight down and motors small you have to limit the stress on that motor or you'd burn it up.

Jim

E_Dawg · October 8th, 2004, 18:14

I *think* in the Arrow II you can RETRACT the gear up to 125, but you can EXTEND it at 150 mph or less. But it's been a while.

September 29th, 2004, 16:24	#1
FlyboyZR1 Junior Member Join Date: Feb 2004 Location: MN Posts: 97	Vle vs. Vlo If an airplane has a Vle speed of 150mph, and a Vlo of 125mph, can the landing gear be extended above 125mph? I always thought the gear could be extended below Vle, and that it can only be retracted below Vlo ... but the FAA Handbook says the gear can only be extended below Vlo.

September 29th, 2004, 16:37	#2
gomntwins Senior Member Join Date: Apr 2004 Location: South Dakota Posts: 477	Re: Vle vs. Vlo [ QUOTE ] If an airplane has a Vle speed of 150mph, and a Vlo of 125mph, can the landing gear be extended above 125mph? I always thought the gear could be extended below Vle, and that it can only be retracted below Vlo ... but the FAA Handbook says the gear can only be extended below Vlo. [/ QUOTE ] Vle is the speed at which you can fly around with the gear down and locked into place. If you took off in an aircraft with a Vle speed of 150mph, that means you could, if the gear were extended and locked into place, fly up to a speed of 150mph safely. The maximum speed that you can extend the gear from the retracted position, however, is 125mph, or Vlo. Many aircraft have Vle and Vlo the same speed... but not all. One reason why the speeds may be different are the aerodymanic principals of the gear while in transit... within the speeds of 126 up to 150, in the case of the example given, the forces placed on the gear may be too much and could cause a threat. Or maybe at that speed, the gear may not come down because of the speed. However, if the gear is already locked into place by 125mph, you can safely reach a speed of 150 without having gear doors fly off, or worse.

September 29th, 2004, 16:40	#3
USMCmech Old Skool Join Date: May 2004 Location: Dallas TX Posts: 1,607	Re: Vle vs. Vlo MOst airplanes have a Vlo speed to keep the nose gear from slaming back into the gearwell too quickly. (most light airplanes) However some others have gear doors or other pieces that move durring gear extension or retraction that can't handle the stress of a higher airspeed. (the B-707 comes to mind) So Vlo applies for both extension and retraction. Then you can speed up to Vle.

September 29th, 2004, 17:24	#4
FlyboyZR1 Junior Member Join Date: Feb 2004 Location: MN Posts: 97	Re: Vle vs. Vlo Thanks, got it.

September 29th, 2004, 18:48	#5
kellwolf Old Skool Join Date: Jun 2003 Location: Memphis, TN Posts: 13,634	Re: Vle vs. Vlo [ QUOTE ] If an airplane has a Vle speed of 150mph, and a Vlo of 125mph, can the landing gear be extended above 125mph? [/ QUOTE ] Hmmm, Seneca huh? Think about the nosewheel and which direction it retracts. It would have to retract against the relative wind, and it's only safe to do so below 125 mph.

September 29th, 2004, 19:05	#6
FlyboyZR1 Junior Member Join Date: Feb 2004 Location: MN Posts: 97	Re: Vle vs. Vlo [ QUOTE ] Hmmm, Seneca huh? Think about the nosewheel and which direction it retracts. It would have to retract against the relative wind, and it's only safe to do so below 125 mph. [/ QUOTE ] Close ... it's an Arrow II.

September 29th, 2004, 21:25	#7
moxiepilot Old Skool Join Date: Aug 2004 Location: CFI / CFII in PA Posts: 2,661	Re: Vle vs. Vlo [ QUOTE ] Think about the nosewheel and which direction it retracts. It would have to retract against the relative wind, [/ QUOTE ] Not only that, but gravity too. Gear doors are usually a limiting factor for speed, but gravity and wind can put too much strain on the torque tube or chain for the system to safely handle. -mox

October 8th, 2004, 15:15	#8
C650CPT Senior Member Join Date: May 2003 Location: Home Sweet Home! Posts: 957	Re: Vle vs. Vlo It has to do with the motor moving the gear, the aerodynamic forces working against the motor is the reason for the limit. Most gears can take the stress but to keep weight down and motors small you have to limit the stress on that motor or you'd burn it up. Jim

October 8th, 2004, 18:14	#9
E_Dawg Moderator Join Date: Apr 2002 Location: chicago Posts: 4,168	Re: Vle vs. Vlo I think in the Arrow II you can RETRACT the gear up to 125, but you can EXTEND it at 150 mph or less. But it's been a while.

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