Tachometer

[mike londke]

Where can I get a currently available, reliable tach. What's everybody using? Thx.

[Dave_Trible]

Mike I'm not sure any hobby supplier still makes a tach.  My son in law found someone selling a handful of Tower Hobbies tachs on eBay a year or two ago and bought them, keeping us supplied for a while.  I did see one that might be good at VXB.com Ball Bearings.  It lists about $30.00 and may be worth trying.

Dave

[Bill Morell]

Still using my Heathkit Thumbtach. Works great. See them on eBay occasionally.

[Leester]

Tower Hobbies shows a Hangar 9 Mini Tach, 35.99 and lists it as in stock.   P/N Han156

[Paul Van Dort]

I use a DT-2234C+. Check google.

[Paul Smith]

Engine RPM, an I pad fone app for $8 works OK for me.

It sometimes gets double or quadruple readings for a while, but this is obvious and easy to correct.  This is due to reflected waves off objects.  You can do airborne readings.

It also takes and records RPM at intervals that you can set.

It does 2-stoke & 4-stroke and different numbers of cylinders, too.

This spring I might put it on a stand in the center, set to 1-second intervals and do a stunt or combat flight.

[Brett Buck]

Engine RPM, an I pad fone app for $8 works OK for me.

It sometimes gets double or quadruple readings for a while, but this is obvious and easy to correct.  This is due to reflected waves off objects.  You can do airborne readings.

It also takes and records RPM at intervals that you can set.

It does 2-stoke & 4-stroke and different numbers of cylinders, too.

This spring I might put it on a stand in the center, set to 1-second intervals and do a stunt or combat flight.

      Definitely a good choice, and if you narrow the range guess to cover only the possible RPM, very reliable. We were using mine the other day to measure the in-flight RPM, which was very interesting, both how much it drops on 4-2 break engines in the maneuvers and how fast some of them turn in the air (25LA/9-4 was well north of 14,000 RPM in level flight, and hit 15,500 right before it quit).

     Brett

[Dave Harmon]

      Definitely a good choice, and if you narrow the range guess to cover only the possible RPM, very reliable. We were using mine the other day to measure the in-flight RPM, which was very interesting, both how much it drops on 4-2 break engines in the maneuvers and how fast some of them turn in the air (25LA/9-4 was well north of 14,000 RPM in level flight, and hit 15,500 right before it quit).

     Brett

Does the app measure audio pulses or is it optical?
I am guessing audio if you can get in flight RPM.
If audio....I wonder if Doppler effect is affecting the RPM readings??

[Brett Buck]

Does the app measure audio pulses or is it optical?
I am guessing audio if you can get in flight RPM.
If audio....I wonder if Doppler effect is affecting the RPM readings??

   Audio. You can see the Doppler affecting it if you observe from the outside, but if you sit in the center of the circle, that goes away. You can also set the update rate/averaging time, to get better reading on the degree of change. The trickiest part is setting the range guess, you need to get that right to make sure you are not getting harmonics. It seems to work on electric, too, presumably from the sound of the blades.

     Brett

[Reptoid]

Does the app measure audio pulses or is it optical?
I am guessing audio if you can get in flight RPM.
If audio....I wonder if Doppler effect is affecting the RPM readings??

As long as the distance from Tach to airplane is constant, there is no relevant doppler shift. Like pilot with tach in center

[Mark wood]

Mine works from up to about 100m away. And it records, both rpm & temperature. L

That bar just got set to the stratosphere .....

[Dan McEntee]

   Years and years ago, Warren Kurth would attend our Speed Contest to fly 1/2A and he had a stationary device that his pit man would position at the edge of the circle for each flight. I think it measured RPM, lap speed, wind,  temp, humidity, stage of the moon, what he had for breakfast and who knows what all! After each flight they would sit in the car and go through what all it had inside it. It wasn't very big, just sat on the ground at the edge of the circle and one specific end was pointed at the center. He was probably one of the most consistent speed guys I think I ever, at least at our contest.
  Type at you later,
   Dan McEntee

[Dave Harmon]

As long as the distance from Tach to airplane is constant, there is no relevant doppler shift. Like pilot with tach in center

Well Duh.....there was no mention of where the tach was located so that's why I asked the question.   

[frank williams]

So what was the name of the phone app?

[Mark wood]

Hehe..
I have 5 measurements/second for rpm and 1/sec for temperature. But I can only measure up to about 150°C with this sensor, so I’m limited to stuff like crankcase- fuel- and maybe cylinder head temperature.
I can download a flight into card just by pressing the button, for later processing with Exel.
My wet dream would be to have the real-time data together with video image.  L

I understand. That's a bit more than the small devices can manage. Best you could hope for is to sync your video clock which would still be nice.

[AMV]

Hehe..
My wet dream would be to have the real-time data together with video image.  L

If only...



Cheers
-Andrey