Can someone explain the difference between V_LE and V_LO speeds?  I know what the dictionary/wikipedia definitions are (V_LE = max landing gear extended speed; V_LO = max landing gear operating speed), and I've seen these speeds listed in the specs for certain aircraft.  But I guess I'm confused about what they means in terms of when I should/shouldn't fly with the landing gear, and when to retract/extend them takeoffs and landings.  They kind of seem like one and the same, no?

 

Also, I'm mostly a GA flyer (and a newbie at that!), so is it safe to say that fixed-gear aircraft like the C172 don't actually have V_LE and V_LO speeds at all?  Thanks.

I'll try and keep it pretty simple as this can be WAY over-complicated.

 

Vle refers to a speed which as you posted is when the gear is down and locked. Much of the speed restriction actually comes from the gear doors and other wind sensitive equipment that is extended. Gear doors/small protruding objects cannot take speeds higher than Vle but the gear can much of the time.

 

Vlo is about the pressure which is put onto the system which raises and lowers the gear. This is a hydraulic system the majority of the time and when the gear unlocks from down position, wind resistance puts a large stress onto the hydraulic lines. This happens on both gear up and gear down. The motor may also have pressure restrictions in regards to how much it can push or pull.

Hmm,.  So basically the aircraft shouldn't be going faster than the Vle speed with gear out once it's fully extended (& locked into place) ... and I'm guessing this is generally going to be a higher number than the Vlo speed, no?

 

And if I have this right, an aircraft shouldn't be the going faster than the Vlo speed regardless unless it's fully locked & extended, and thus it will usually be a lower speed than the Vle.  Am I way off?

Hmm,.  So basically the aircraft shouldn't be going faster than the Vle speed with gear out once it's fully extended (& locked into place) ... and I'm guessing this is generally going to be a higher number than the Vlo speed, no?

 

And if I have this right, an aircraft shouldn't be the going faster than the Vlo speed regardless unless it's fully locked & extended, and thus it will usually be a lower speed than the Vle.  Am I way off?

 

 

Correct, Vle is your "Vne speed" when the gear is down. Vlo will never be above Vle but it may be the same for one direction or both depending on the airframe.

Awesome.  Thanks t_bergman!  That's was a lot clearer than the many many highly detailed explanations out there.  This newbie appreciates it.  Cheers.