Nose wheel door hyraulics.

[ouPhrontis]

I've noticed on cold and dark that the nose wheel doors are closed, and although this isn't necessarily wrong; I understand that when there's no hydraulic pressure the doors would open, this comes from some comments made by some mechanics that claim to have worked on them.

 

Here's an overview:

 

The doors for the nose wheel are hydraulically actuated and once there's hydraulic pressure built up they close and only open when the gear is cycled, or when someone manually relieves pressure via a valve.

 

'LanceB';

Harrier nose gear doors are hydraulically operated. Main gear doors are operated by a mechanical linkage system. Doors open when gear is cycling up or down and close automatically when the cycle is completed. Both the nose gear and main gear doors can be opened by human intervention once the aircraft is parked. For main gear doors you just reach in and release a mechanical lock and the doors drop open. They can be recluse simply by pushing them into the up position, they will automatically lock themselves closed again.

 

The nose gear doors are opened by relieving hydraulic pressure via opening a valve. IIRC (it has been almost 3 decades since I list did it...) on the Harrier Gr.1/3/AV-8A/SHAR the valve was inside a small access panel just forward of the nose gear doors. Pop the valve, pressure bleeds, doors drop open. They will not reclose and will not lock again even if pushed back into the closed position. Due to the valve arrangement inside a panel (which, again if I am remembering this right) there was no obvious external sign that the valve had been activated as there was on the GR.5/7/9/T.10/12/AV-8B as you were supposed to close the door and not leave it hanging open as it was susceptible to damage.

 

and

 

'Shar2';

As @LanceB has said the nose-wheel doors were opened via a red toggle valve on the starboard side nose. This was always done just after the pilot had shut the engine and APU down. The main doors used to sag a bit once hydraulic pressure had dissipated and could be opened by pulling a latch in the main wheel bay. The main doors would be released if work needed to be done in the bay, usually changing the gun firing fuse in my case

 

Here's some footage of hydraulic pressure apparently building on starting up the Pegasus and the nose wheel doors closing;

 

 

Quotes pulled from this discussion;

https://www.britmodeller.com/forums/index.php?/topic/235009874-sea-harrier-question/

 

This is intended as help to make the module even more of a great replication.

Edited May 12, 2018 by ouPhrontis
removed extraneous empty lines and correction on main. Added link to other discussion and some video links.

[ChickenSim]

Little bit of additional cocktail trivia, during High-G flight the weight of the nose gear could also overcome the hydraulic pressure keeping the doors shut, causing them to open a bit in flight until the pilot let the G off.