Digital vs. Analog tach

H. Paul Shuch is a Light Sport Repairman with Maintenance ratings for airplanes, gliders, weight shift control, and powered parachutes, as well as an independent Rotax Maintenance Technician at the Heavy Maintenance level. He holds a PhD in Air Transportation Engineering from the University of California, and serves as Director of Maintenance for AvSport of Lock Haven.

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ShawnM
Posts: 227
Joined: Sat Nov 11, 2017 9:59 pm
Location: Clearwater, FL

Re: Digital vs. Analog tach

Postby ShawnM » Wed Apr 25, 2018 8:55 pm

I've used the MGL gauges before in an experimental helicopter I was building. They make very nice instruments with very reasonable prices. Certainly worth looking into in my opinion if you are considering a new tach.

But one again, if it ain't broke......... :mrgreen:

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FastEddieB
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Location: Mineral Bluff, GA

Re: Digital vs. Analog tach

Postby FastEddieB » Thu Apr 26, 2018 8:09 am

Step 1 is covered - a mechanic a Copperhill has access to a handheld prop tach device.

Will report results when I have them.
Fast Eddie B.
Sky Arrow 600 E-LSA • N467SA
CFI, CFII, CFIME
FastEddieB@mac.com

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FastEddieB
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Location: Mineral Bluff, GA

Re: Digital vs. Analog tach

Postby FastEddieB » Fri Apr 27, 2018 7:02 pm

Good news!

We ran a test today. I would run up the engine to a given indicated RPM, and my mechanic friend would "shoot" the prop with his handheld optical tach.

Results, after applying the gearbox reduction factor:

Image

Pretty darn close - or at least close enough for government work!

As an aside, we had one prior member insist his brakes wore out so fast because of the high idle rpm on a ROTAX necessitating more brake usage. This points out that even at a relatively high idle of 2,000 rpm, the prop is only turning around 800 rpm, not far off from the typical Continental or Lycoming.
Fast Eddie B.
Sky Arrow 600 E-LSA • N467SA
CFI, CFII, CFIME
FastEddieB@mac.com

proemer
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Joined: Tue Apr 24, 2018 10:25 am

Re: Digital vs. Analog tach

Postby proemer » Sat Apr 28, 2018 8:45 am

Thanks for the report, Eddie. Now I need to see which of my tachs is right... (if either!). I tend to think the digital Dynon display should be accurate... but who knows.

Pete

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Jim Hardin
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Re: Digital vs. Analog tach

Postby Jim Hardin » Mon Apr 30, 2018 4:33 pm

Nice work eddie!


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