Compression Test Altitude Correction - February 6, 2010
This is for me more than anyone else, I spent far too much time looking for this info each time that I need it! Compression data is usually based on 14.7 atmospheric pressure and 59F at sea level. There are factors to compensate for the different altitudes and the corresponding temperature differences. These are as follows: 1000' = .9711, 2000' = .9428, 3000' = .9151, 4000' = .8881, 5000' = .8617, 6000' = .8359, 7000' = .8106, 8000' = .7860. The equivalent compression reading for a cylinder that should be 135 PSI by the data at 5000' would be 135 x .8617 = 116.33.
Center Hole Punch - July 23, 2002
Seems like I am always trying to drill a bolt hole in something that must line up with an existing hole. To accomplish this task I have made myself a set of "center hole punches." They are made from old bolts! I simply cutoff the head, chuck the remainder in the lathe, trim it down to a nice point, and then cut a small groove. I use a screwdriver (in the slot) to screw the "punch" into the hole, align my "part", give it a tap with the hammer, and then drill the hole at the punch mark. Whalla - a perfectly aligned hole!!
Instrument Panel - September 6, 2009
Do not waste time or money on old fashioned steam guages. There are so many all electronic options now that the prices have become very reasonable. It is easy to equip a new plane with at least an engine monitor that provides SO MUCH information and does not cost more than individual guages. The same is true for flight instruments if building a VFR airplane (maybe for an IFR ship too but I don't pay much attention to the high-end equipment).