tachometer
 

Is there an accurate tachometer that you can recommend?

I've used one from Tower for many years w/o any problems or complaints.

I purchased one about 10 years ago. I used it for a few months. I then realized that it was not giving me any more information than I already had, or perhaps, was interested in. I have not used it for about 9 years.

+1 on the tower hobbies tach.... I just realized I bought mine in 1989 .... :) still works great.

Over 20 years in the hobby, here. I've never owned a tach. I've never felt the need.

I bought mine to tune my 4- strokers......just the other day a guy was tuning his FS and was having a difficult time getting it stay running....I used my tach and surprise - he was running the engine too lean. A couple of clicks and now he is a happy camper!

I got a Hobbico one. I think it is accurate, but sometimes it reads double or some strange reading before it settles down, and then does it once in a while. I use mine a lot to see if modifications help or hurt, pick props, and just to select which motor for which plane etc.

I was rebuilding and working on so many different types and brands of engines several years ago that I finally had to break down and buy a good tach. I had both the Hobbico and GloBee and neither of them were accurate enough, I finally bit the bullet and bought the TNC tach, it's perfect and accurate but at $100.00 I question the need for most sport pilots. I compared it to other tachs every chance I had and one thing became clear to me, there was/is a combo tach sold through Horizon that is a combo volt meter tach and everyone I checked against mine was spot on. I do use my tack to tune the older type of YS engines because they are a balancing act to get the high and low ends adjusted and I can't hear the rpms when I get the sweet spot. I need it to tune a couple of gas engines I have too but I can still get away without one. Everyone needs a good volt meter though and that combo tach and meter from Horizon is a much better idea then just a tach. TNC makes a great tach though but is it worth $100.00??? It was at the time but doesn't get used all that much these days.

You can improve the accuracy of the cheap tachs by having a plain white background in front of your plane. They work the same way bullet chronographs do, by seeing the dark flash go by. The more contrast you give them to work with, the more likely they are to get a good reading.

Not having a calibrated ear, I use a tach every time I set up a new engine / prop. I feel that it is important to know whether the rpm is meeting expectations and I just can't tell the difference between 8,000 and 9,000 rpm or whatever.

I have tried the Hanger 9 digital volt/tach and got good results from the volt meter, but the tach was unreliable and entirely too sensitive to background lighting. Later, I ordered the Fromeco TNC tach - it seems to read correctly no matter the lighting, the background, or the orientation. Like I said, I only use it a few times per year and then only at home when setting up a new engine.

http://www.rcuniverse.com/forum/atta...mentid=1925671 This is my normal background at the lake bed, photo is of Rick Stubs with one of his UpRoars last week. That will be another story told! I used my TNC that day. It doesn't care about the background very much. In this light and background I do need to be closer to the prop, with grass or asphalt as a background I can stand 4 feet behind the prop and get good readings. That's what 100 bucks will get you. Other tachs are more sensitive to the different light and backgrounds. Most of my glow engines are YS and I have discovered they all seem to like to be 500rpm fat at the top end. I can hear the drop but the tach shows me exactly how much. Once I tune one of my engines I don't change the needles for about 6 months when the weather changes a lot or if I change the prop size. Tachs come in handy but not often enough to spend the big bucks on one. I needed one at one point so I have a good one but it isn't used much these days.

The nice thing about most tacks, even the very cheap ones, they are easy to calibrate if you have AC power (at least in the USA) as you can use the 60 cycle/second as a calibration point. This will show up as 120cps (7200 RPM) with most light sources and is very accurate.

I mostly use a tach to compare different props and so far my early 80's vintage Royal Digital Tach is still working great, and better still it can be calibrated.

Most of my tach use is for setting the lsn. I can tell exactly when I have the idle peaked without waiting to see if the engine is going to load up. It's a real time saver when getting the initial tune on a new setup. The HSN I set by ear and then tweak by watching how it flies. I do like to then check how many rpm rich I am on the ground so I can repeat my results. I've been surprised a few times at how rich an engine likes to be and what actual idle rpms are and can be.

I'm happy with my Glowbee tach. It's about the same as the Tower. It reads a florescent light at the correct rpm, so I assume it is accurate.