-asked, here are a few photos are from snap-ring case forward closures
-machined by Bdale for
-test flights of EasyMotor. The sensor bodies are 316 stainless with a 1/8 NPT
-male boss, so the approach chosen is to drill a 1/8 inch touch hole all the
-way through the closure, then drill and tap 1/8 NPT female threads part way
-through the closure thickness. The hole gets filled with grease and the
-sensor screwed in. The first example is a 98mm snap-ring clossure, with the
-sensor and electronics mounted off-center so a 3/8" all-thread could be used
-in the center for motor retention in a minimum-diameter-ish airframe. The
-mounting bracket for the electronics was bent from a bit of 1/16" aluminum
-sheet and screwed to the forward closure with two short 4-40 screws into
-tapped and drilled mounting holes. Note the use of an A23 12v alkaline battery
-in a holder on the bracket wiht the
-EasyMotor prototype. These batteries are fine for a flight or two, and both
-they and the little holders for them are cheap on Amazon and make installations
-like this fairly easy to put together:
+asked, here are a few photos from snap-ring case forward closures
+machined by Bdale for test flights of EasyMotor. For launch detection to
+work, the board must be mounted so the board's long axis is aligned with the
+axis of flight, and by default the "beeper end" must be towards the nose.
+Note that these examples all feature earlier versions of EasyMotor that used
+a different power supply and battery strategy. Don't be confused by that! The
+production version of EasyMotor uses our standard Altus Metrum LiPo batteries.
+
+The body of the pressure sensors used are 316 stainless with a 1/8 NPT
+male boss, so Bdale's usual approach is to drill a 1/8 inch "touch hole" or
+sampling port all the way through the forward closure, then drill and tap
+1/8 NPT female threads part way through the closure thickness. The hole
+gets filled with grease, and then the sensor screwed in. Since Bdale usually
+builds airframes that assume the recovery harness can attach to the motor
+case, several prototype installations depended on the stainless steel sensor
+body to act as a bolt to attach a bracket that supported both circuit board
+mounting and recovery harness attachment.
+
+The first example is a 98mm snap-ring closure, with the sensor and
+electronics mounted off-center so a 3/8" all-thread could be used
+in the center for motor retention in a minimum-diameter-ish airframe. This
+motor had a small gap between the forward propellant grain and the forward
+closure, so having the pressure sampling port off-center wasn't a
+problem. The mounting bracket for the electronics was bent from a bit of
+1/16" aluminum sheet and screwed to the forward closure with two short 4-40
+screws into tapped and drilled mounting holes. Note that this early version
+of EasyMotor used an A23 12v alkaline battery in a holder on the bracket. Those
+batteries were fine for a flight or two, but dealing with them was a hassle,
+which is one of the reasons the production was designed to use a LiPo.