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Q-talk 93 - Westack Woes

Sam Hoskins Murphysboro, IL

I'm trying to develop some good performance numbers to properly size my prop. I have always suspected that my Westach tachometer was inaccurate. Is it ever! I flew last evening using a highly accurate, non-contact, Simco electronic tach to cross check my Westach. I got the following readings:

Westach

2,400

2,500

2,600

2,700

2,800

Actual

2,148

2,272

2,357

2,449

2,581

Average error is -238 RPM.

I just wish I had a second instrument to further verify the accuracy of my little experiment. The morale of the story here is, make sure the instrumentation is correct before making changes to the aircraft. This holds especially true for engine conditions, such as the cylinder head temps and oil pressure.



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