> cupra wrote:

>> Enzo Matrix wrote:

>>> Mel Rowing wrote:

>>>> On 4 Jun, 22:41, allan tracy hotmail.com> wrote:

>

>>>>> He was just about to pull the gear up lever (the wheels) when they
>>>>> finally noticed him.

>>>> You can't raise or lower the landing gear unless the hydraulic pumps
>>>> are operating.

>

>>>> Perhaps they left the engines running too!

>>> There is also a circuit that routes through a microswitch on the
>>> undercarriage. If there is weight on the wheels, the circuit will be
>>> broken and the undercarriage cannot be retracted. Only when the
>>> aircraft is airborne is the circuit completed, allowing retraction to
>>> commence.
>>> Some military pilots will select "wheels up", before commencing their
>>> take-off roll, so that as soon as the aircraft lifts off, the gear
>>> comes up. It's a bit dangerous to do so though, as a bumpy runway can
>>> cause the aircraft to bounce slightly before flying speed has been
>>> attained, leading to the aircraft settling back on its belly.

>

>> Haven't they heard of hysteresis then?

>
> Is that where people get all excited for no good reason?- Hide quoted text -