richbran

Ian,

There are several ways to operate the gear/door mechanism, that determines also the way the small doors open.

Each system has its pre- and cons. I chose a system based on 2 X (jettronics) electric valves, one for the doors, one for the gear.
For the 2 small nose doors I used a BVM mechanical pneumatic switch. That is, the nose strut operates a switch that can open or close a pneumatic valve.

Setup is that both small doors get OPEN pressure from the GEAR system when selected gear DOWN. They open then simultaneously with the (nose) gear.
Same for doors CLOSE, it will get get pressure from the gear UP line, however, the pressure cannot reach the doors yet, as it is blocked by the switch.

As soon as the nose strut is almost retracted, it contacts the switch and lets pressure go to the doors.
Sounds simple, but got me a while off the street to figure it all out!'

Btw my friend Leo who builds another MB went up the route with mechanical valves, he uses the UP4/UP2 combo.

Together with Leo we drew the setup in a worddoc, here is a scan, I don't know if it will readable, I could not upload a worddoc. If needed I can send it by email.