Monday, December 24, 2012

Merry Christmas From DOG Aviation!

Twas the night before Christmas, when all through the shop not a rivet was stirring, not even a pop; Well you get the idea … Merry Christmas from DOG Aviation!!

Earlier in the day, in an effort to move forward with the project no mater how small the task, a small amount of time was spent machine countersinking the VA-195A mounting plate for the stall warning indicator’s micro-switch. The mounting plate has two holes that accept #4 screws used to mount the micro-switch for the stall warning indicator system. These two holes are drilled out to #30, then machine countersunk using the 100 degree #30 countersink bit until the #4 screws set flush into the VA-195A mounting plate.
                               Machine countersinking the two holes on the VA-195A mounting plate which
                               will accept the #4 mounting screws for securing the stall warning micro-switch.

The VA-195A has another hole that receives a #8 screw which also requires machine countersinking … this hole is drilled out using a #19 drill and machine countersunk using a #20 countersunk bit. This #8 screw will be both a mount and pivot point for a vane that has a downward bend where it protrudes through a small slot in the wing’s leading edge and into the airflow.

The theory behind this assembly is simple … under normal flight conditions, because the vane is bent downward, the wind will push down on the vane preventing the vane from rising and tripping the micro-switch. However, when the angle of the wing becomes higher (as when approaching a stall) the airflow will get under the vane, lifting it, thus tripping the micro-swich causing alarms to sound in the cockpit.
                              Finished VA-195A mounting plate, machine countersunk and ready for assembly.