Re: REFLECTOR: sequence valve location

["David M Parrish" <dmp@radbsd.mcg.edu>]

From:           	Dave Black <asterisk@erols.com>

> The "trick" to eliminating nose door slamming is to locate the sequence valve
> as near to a linkage pivot point as possible. It takes an awful lot of force
> to depress this valve, so the more leverage you can get, the better. 

That's the real solution, though leverage isn't the only problem.

I didn't particulary like the sequence valve inside the console, (With my big 
hands, installation and adjustment would be a nightmare.) so I mounted it on 
the front of the canard bulkhead so the gear would press the control. It 
worked, after a fasion. While everyone else was getting a big *SLAM* as the 
doors closed, I got a *SLAM-SLAM-SLAM*. It sounded like a M-16 doing a 
three round burst.

What was happening was as the valve depressed, pressure was released 
into the door cylinders, whacking them up a notch, and the gear would drop 
slightly from the loss of pressure, closing the sequence valve. Then the 
pressure would build again and the cycle would repeat. A bed of silicone for 
the gear to rest in helped, (Reducing bounce from the top of travel.) but the 
final solution was a one-way restrictor valve so the door cylinders wouldn't 
see a burst of high pressure fluid.

Of course, now the retriction is too great and the pump pressure builds to 
cutoff before the doors are fully closed. Then, as is the pressure bleeds down 
for a two count, the pump comes on again and everything closes like it 
should.


The important part is to have the valve placed where relative movement is 
small. That way, changes in line pressure as the valve opens doesn't cause 
large variations in the opening of the valve. It also opens the valve in finer 
degrees so the door cylinders don't get a sudden burst of high pressure fluid.

---
David Parrish