Sunday, July 20, 2008

A Simple little thing..

We are running the main tank pressure on the vehicle at very close to the absolute minimum spcified by the FAA experimental vehicle strucural guidlines. Our design pressure has a safety factor of two, but our test pressure has a SF of 1.25.


What does this mean? It means that no human should be within the blast radius while it is presurized. This implies a remote actuated quick disconnect.


A simple thing in concept a whole afternoon in acutality. The Quick disconnect needs to be reliable, and rugged. Each time its actuated its going to fall from several feet into the dirt or onto concrete.


Here is the result:


Qdbusinessned


Qdotherend


Two Aluminum arms are hose clamped to the barrel of a normal penumatic quick discconnect. These arms are fastend to the nut at the front end of an aircylinder (Mcmaster carr 6498K171) The plunger of the air cylinder threads into the back side of a brass plug that has been taped to match the aircylinder rod end thread. The brass plug pushes on the brass Tee and the aluminum arms pull the QD free. It works really well and is almost insdstructable.


 Here is the totally bogus video tour.

3 comments:

George Katz said...

Nice work on that Paul. Looks nice and simple.

I noticed that you were able to just activate it by hand.

Is there any chance that the hose you will attach to the brass T (I assume is a flex hose) will tend to want to straighten under pressure and have enough force to activate the release?

Paul Breed said...

It is a legitimate concern, like everything else it needs to be tested.


Paul

ChrisPhoenix said...

Speaking of pressurization... I read your FAA application, and spotted a potential issue.

Once you pressurize, you need battery power to run the computers and activate the valves to depressurize. But in your launch sequence, you check battery voltages after you pressurize. It seems unlikely to be a problem in practice, but it doesn't look like you have a contingency plan for depressurizing if all your batteries are flat.