Retired in Hopkins, MN

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Robert Scott

Member
Joined
Oct 22, 2019
Messages
8
Location
Hopkins, MN
Hello from Hopkins, MN. I am a private pilot who has not flown in 7 years. My interest is in the technology of aviation. I grounded myself for medical reasons, but I remain keenly interested in general aviation. Years ago I designed some aircraft system controls (non-critical) for freight aircraft, and some test equipment for aviation. And right now I am developing an instrumentation app and that is one of the reasons I am posting here. I have under development an app for Android phones that measures the RPM of an engine from the sound of the engine. Before I release it generally, I would like some feedback on it. If anyone wants to test it for me, I can give you a code to get the app for free. Just open a conversation and I will give you a promo code. The app is called "Engine RPM." I actually started development on this app when I was in a flying club at Willow Run Airport in Michigan. I wanted to check the calibration of the tachometers in our club planes. I released an iPhone version of the app too early while it was still unreliable and I don't want to make the same mistake with the Android version. That is why I am asking for help to check out this version before it gets released generally. So if anyone has an interest in measuring RPM from sound, I would appreciate any feedback you can give me.

-Bob Scott
Hopkins, MN
 

Robert Scott

Member
Joined
Oct 22, 2019
Messages
8
Location
Hopkins, MN
Great idea! Hope you get a lot of interest.
Thanks! I had a lot of fun developing it. Sitting at Ann Arbor airport when there was only one plane doing a run-up at the start of RWY 24, I could measure the mag drop as the pilot checked L, R, and both - from a quarter of a mile away! However once he started his takeoff roll, the Doppler effect distorted the reading.
 

wsimpso1

Super Moderator
Staff member
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Joined
Oct 18, 2003
Messages
6,784
Location
Saline Michigan
Thanks! I had a lot of fun developing it. Sitting at Ann Arbor airport when there was only one plane doing a run-up at the start of RWY 24, I could measure the mag drop as the pilot checked L, R, and both - from a quarter of a mile away! However once he started his takeoff roll, the Doppler effect distorted the reading.
I am based at ARB, live a few minutes away. You there often? We can look at the project, go flying, or go get a beer..

On a different topic, have you looked into Basic Med or going LSA without a medical?

Billski
 

Robert Scott

Member
Joined
Oct 22, 2019
Messages
8
Location
Hopkins, MN
I am based at ARB, live a few minutes away. You there often? We can look at the project, go flying, or go get a beer..

On a different topic, have you looked into Basic Med or going LSA without a medical?

Billski
I used to live near Ann Arbor, but we moved to Minnesota 7 years ago. As for the medical, I was not rejected. It was purely my decision. I just didn't feel safe anymore.
 

Deuelly

Well-Known Member
Log Member
Joined
Nov 6, 2012
Messages
212
Location
Marshall, MN
Hi Robert,

I'm in Marshall MN. I work in Granite Falls.

Does it matter how many cylinders? I've got a bunch of V-12 aircraft I maintain that I wouldn't mind trying it on.

Brandon
 

Dana

Super Moderator
Staff member
Joined
Apr 3, 2007
Messages
9,256
Location
CT, USA
Hi Bob, I would be very interested in testing your app. As a matter of fact I was recently looking for such an app, and was surprised to not find one. Now looking again I see a few others with poor reviews. I'm about to test a new prop on my plane and would like to verify the tach's accuracy.
 

Dana

Super Moderator
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Joined
Apr 3, 2007
Messages
9,256
Location
CT, USA
Thanks, Bob! Tried it with the sound from some video files I recorded awhile ago. Wind noise in the gopro microphone makes it flaky, but on one good clip I have it's stable and seems pretty close to what I would expect. I'm hoping to go flying tomorrow after work when I can give it a real test. It will be interesting to see how it works with the phone down inside the [open] cockpit.

Your timing is awesome, just when I need it!

A couple of comments:
  • It'd be nice if the min and max rpm were displayed and updated while swiping to change the hint and and tolerance.
  • When it loses the "lock", continue to display the last known rpm for a few seconds, perhaps changing the color to indicate it's not a live reading.
  • With auto-ranging, I got nothing, even though the graph looks like a clearly defined pattern of peaks.
  • Thank you for writing a manual that clearly explains what's going on, instead of the dumbed down manuals one too often sees nowadays. Non technical people will probably be baffled by the software, but gas engine R/Cers will love it.
 

Dana

Super Moderator
Staff member
Joined
Apr 3, 2007
Messages
9,256
Location
CT, USA
Used the app yesterday during new prop testing. Worked great, though it occasionally lost the lock. Looks my tach reads about 20 rpm low. A GoPro pointed at the panel served for data collection:

upload_2019-10-27_16-13-54.png
 
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