Tach hop-up :P

After going through the thread on tachs, I figure the only real difference is the ability to actually read a prop reliably in any light.

SOOOOOO....

I took my GloBee tach (it has always had pretty miserable "reception") and worked it over. I replaced the lens in front of the receptor with a slightly more powerful one, then added a 2nd lens at the end of the receptor barrel. When you look into the unit the receptor looks about 4 times actual size. This means that going the other way, it picks up about 4 times as much light from straight ahead as it did before.

Finally, I added a long "lens hood" of plastic tube that was painted black on the inside.

We will see how it now works in the field, but in my office, it will pick up a flourescent table lamp from across a room lit by non-flourescents, and the pickup is directional +/- 15 degrees or so.

It may not be perfect, but it has GOT to be an improvement!

The lenses I used were ripped off from scrap toys, and pretty random focal length and miserable quality. If you did the optics properly to give a truly columnated beam, it could give a pretty spectacular performance boost.

Larry, how about scavenging lenses off disposable cameras?

Yes, those should be of exceptional quality. Great idea.

The one feature that I would like to see is some way to hold the tach, the airplane and adjust the needle valve all at the same time.

Maybe some sort of thumb clip on the tach so you can grab the fuselage just ahead of the wing, with the tach pointed at the prop. Then you could even pick the plane up and adjust the needle with the nose pointed up and still read the dispaly...

Velcro it to the back of your hand????

You need the Futaba digital tacho, it has a little flip down leg that means you can rest it on the ground and it looks up at the prop whilst positioned somewhere that you can see it, worked good on pylon racers F1 and FAI F3D.

I have one of these Futaba tachs, as back then it was the only one of readily available tachs which would read past 30K. Still use it as a back-up as it is a little awkward to handle, having to scroll though time-down and time-up counts.

They do not seem to be available. Am I wrong on this?

Speaking about tachs, when was the last time the lens was cleaned? I cleaned mine last night with some alcohol and the Q-tip was pretty dirty afterward. I was a little surprised. Then I realized that my Thunder Tiger tach had 2 adjustment pots. Years ago I had drilled the case to use a small screwdriver to adjust these pots. I pointed it at the light and adjusted the 2 blade setting to read 3600 and the 3 blade setting 2400. Sure enough my tach was off and after adjusting I'll check it against my buddies TNC. Shoot, might just readjust it at the flying field on a running engine with his as the master.

Crist,
I propose you decide what rpm you want your engine to run at and adjust the tach to give you that number!

Larry,
I propose that you ask NASA to put it up on the (I) Space Station and see if you can read your hopped-up Hyper-Viper on the ground!

Only if I get to take it up there in person. Someone else can run the engine.