View Full Version : How to measure headspeed?
Hover_X
05-05-2008, 01:33 AM
1. How do you guys measure head speed?
2. What is a good head speed at hover for a guy that can proficiently hover and move the heli around (tail in)?
Jetleaf
05-05-2008, 01:51 AM
For hover Gaui recommends at least 3000 head speed for hover.
You can measure the HS with a tachometer available at most rc shops
mjr_larkin
05-06-2008, 04:28 AM
For hover Gaui recommends at least 3000 head speed for hover.
You can measure the HS with a tachometer available at most rc shops
Just remember you need a natural light source like the sun to use with your tac, or a DC light source like a flash light. Anything running out of a socket is most likely flickering and there fore won't give you accurate readings with the tac.
J-Heli
05-06-2008, 04:33 AM
About how much does the average tachometer run, and how would you adjust the headspeed to get it to the correct RPM.
rotorhead58d
05-06-2008, 04:58 PM
mine cost $105.00, but it only goes up to 3190 rpm. i was reading about a way you could go higher, but it didn't sound reliable. there is a shutter that spins around inside of it, and a knob to adjust it on the side. 9v battery powered. very simple to use. or you could invest in a laser tach, and pay 3 times that amount. i use mine for my bigger heli's and it works great.
www.modelavionics.com
SurfCity
05-07-2008, 12:52 AM
About how much does the average tachometer run, and how would you adjust the headspeed to get it to the correct RPM.
I use this little Hobbico (http://www.readyheli.com/LCD_Digital_Mini_Tachometer_p/hcap0401.htm) unit from ReadyHeli. $25. Reads up to 32,000 rpm. Must be used in daylight; artificial light messes it up.
mjr_larkin
05-07-2008, 03:09 AM
I use this little Hobbico (http://www.readyheli.com/LCD_Digital_Mini_Tachometer_p/hcap0401.htm) unit from ReadyHeli. $25. Reads up to 32,000 rpm. Must be used in daylight; artificial light messes it up.
:lolol
Jetleaf
05-07-2008, 01:18 PM
:confused:
I have been messing around with a little pc program called "rpm from sound" I have been getting very consistant measurements of my gas motor rpm. You can down load it in about 5 seconds for free. http://www.tunelab-world.com/rpmsound.html
I have set the rpm MIN and MAX to 15000 and 30000 respectively and a rpm = 1 x the fundamental freq for gas.
It locks right on the motor rpm if you set the min and max rpm above the tail and rotor blade frequencies. From here just determine your final drive ratio and you got head speed free of charge.
I have not had enough time to determine if it can lock on the rotor speed directly like would be neccesary on an EP, but I have been able to get a fairly consistent speed of 2650 with my Blade 400. I am certain with the mic in the right place, and the rpm filter eliminating engine rpm as well as the fudamental freq multiplier set to .5 for 2 blades, you could get the head speed directly.
I am getting consistent results, but with no tach to confirm, I cannot comment on the acuracy of this methed. Have fun!
I have been using the audio of my cam-corder but if you have a mic you could go straight to the laptop.