Dezynco

When measuring the rotor speed, where do you hold the tachometer, at the blade tips or near the center hub?

-pkh-

My Feedback: (2)

It's dangerous to attempt to use an airplane prop tach with a heli, since you need to get right up next to the blades to use it. Besides, you want to check the RPMs throughout the collective range, so that means flying it around while checking the RPMs. It shouldn't matter where you put it, though, if you attempt it... it's the same RPM at the tip or the root. I guess it's possible that the blade speed at the tip might be too fast to get a good reading, so going towards the root might be better... and more dangerous!

You're best off getting a heli tach, though...

BarracudaHockey

My Feedback: (11)

You could try holding the tach in your teeth while you hover over your head.

FLYBOY

My Feedback: (11)

Just get a heli tach. I don't want to read about how you cut off your arm or someone elses.

radobahn

The risk involved is obvious and he was'nt asking for an opinion on the possible dangers when checking head speed. Once again, another simple question that requires a simple answer...but as usual around here you get more sarcasm than you do advice.

Dezynco- Most guys tach 2-3 inches from the blade tips...hope this helps[sm=thumbup.gif]

Dezynco

Helicopter Tach?????

-pkh-

My Feedback: (2)

It's kind of like a strobe tach... you look through it, adjust the RPM setting until the blades appear to be stationary, and that's your RPM reading. I finally ordered one myself from Heliproz:

http://www4.mailordercentral.com/hel...?number=804260

This lets you fly the heli around and move the collective through it's full range to check your RPMs.

BarracudaHockey

My Feedback: (11)

Rado, the question of taching a 30 size nitro ship with an airplane tach at hover rpm begs for a touch of saracasim, sorry if you were offended.

PKH is right on the money. Optical tach, you fly, someone tachs (they don't even have to be heli savy) everyone is safe and you get the most accurate reading.

thecheatscalc

But wait if you turn it up fast enough it would catch it every 1/2 rotation and it would look like the blades wern't moving.

PS: why do you need the speed of the blades [&:]

Dezynco

I just want to be sure that I have everything "optimized". No need in wasting battery power (Eco 8). The Eco is flying ok, just want to keep track of things. There are so many different pinion gears and motors available, it would just be nice to know for sure. I guess it would matter more on a bigger helicopter.

fritzthecat

My Feedback: (4)

The easiest - and safest - way to use an airplance tach on a heli is to stake the tach into the ground and then hover over it. Somebody else can use binoculars to read the rpm. Or ducttape the tach to the tailboom (not exactly underneath the paddles) and again use the binocs.

Fritz

radobahn

^^^Very true statement and no offense taken..... I knew he had it coming

Dezynco

What would be wrong with staking the helicopter and the tachometer down, running up the rotor and reading the speed that way? The heli doesn't leave the ground, and I wouldn't have to hold the tach. I could get close enough to read it from 4 or 5 feet away.

-pkh-

My Feedback: (2)

That will give you a reading for couple of degrees of collective pitch... if you increase your pitch at your target RPM, the heli won't be on the ground anymore!

Dezynco

I mean like putting something through the landing gear to hold it down, then I could change the pitch and everthing without leaving the ground.....

credence

My Feedback: (2)

I think that would be alot of unnesecary strain on your components and helicopter frame. The best way for taching using an airplane tach to get in-air readings is to simply mount the tach to the helicopter. Most tachs have big readable displays and so you should be able to get an accurate readout aslong as your eyesight isn't completely terrible .

Honestly, depending on your tach, most work from a pretty good distance away (usually even farther than what the manufacturers say it will work at). And so simply having someone nearby aiming the tach at the blades while hovering will likely give you the readout. My hobbico tach works from like 4 or 5 ft away, which is plenty of room for taching a hovering bird aslong as there's a decent pilot on the sticks.

BarracudaHockey

My Feedback: (11)

My suggestion, is that if you are going to go through the trouble of tach'ing your head to perfect your setup. Then spend a couple bucks and do it safely and correctly.

FYI, your static readings aren't going to give you the whole picture, the rotor head will unload in the air just like static prop measurements aren't what your getting inflight because of disk loading.

quaker1

Get yourself one of these webra tacho`s, piece of cake if you just want to set-up the correct gear ratio.