Pitot tube install on a 50 sized heli - RC Groups
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Jun 01, 2008, 01:18 AM
Registered User

Pitot tube install on a 50 sized heli

Hi Bill,

Count me in as another Eagletree fan! - I just purchased the V3 150amp, Speed sensor, brushless sensor, optical sensor, two temp sensors and suspect I am just getting started!

Here is a photo of my Pitot tube (and general) install on a 50 sized heli (Align 600E with Neu 1515 2.5D, I am hoping that there is no turbulence coming off of the tip of the canopy nose that could affect readings, otherwise I will have to install a brass tube flush with the nose. The sensor is inside the frame with no modifications since its an open "fuselage" and no ram effect - the last photo shows it behind the battery (about 2-3" in front of rear edge of canopy).

Is there a "best" method for a heli since I am also concerned with rotor downwash across the Pitot tube as well - any installation tips unique to a helicopter would be most helpful.

P.S. For the thermistor-type temp sensor, I am planning of using heat-conductive epoxy to glue it to a small aluminum plate and trap it between the battery strap and the battery itself - am I using the best sensor type for this application?

First test tomorrow!
Last edited by blueviewlaguna; Jun 01, 2008 at 02:16 AM.
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Jun 01, 2008, 08:26 PM
Registered User
Hi Bill,

I hovered and did some full-power climbouts and have found a few concerns:

1/ Total mah is consistently 60-65% of the true value, for example the V3 logger showed 1802 and 1624 total cum mah, with my chargers showing 2789 and 2664 respectively. The max amps displayed seems low for this setup and the full power climbouts (max was 47 amps) based on fellow heli flyers' graphs - if I multiply the amps by 1.6 (inverse of the 60% difference between the FDR and chargers), I get amperages that matches other similar setups. I disconnected the ESC and powered up the V3, then Zero'd it with the SW. My Neu 1515 motor is about 3/4" from the Hall effect sensor - can it affect amperage readings? - Virtually any practical mounting location will be near the motor unfortunately.

2/ Voltage is accurate - calibrated with a Fluke 87 V meter and now is dead on.

3/ Updated to 6.53 SW and 5.41 FW - since doing this, airspeed sensor seems to "stick" at high (30-45mph) readings (before, using the SW and FW in package I had spikes to 20 mph even when stationary, but now it plateaus. Plugging the Pitot tube with my finger caused the Live airspeed to rise to 35mph, but upon closing and re-opening the program, it would display 12-15 mph and not rise when plugged. The old SW and FW in package seemed to allow the airspeed to show 0 mph in Live mode much more than this version.

Here is my FDR exported to a JPG, the heli was stationary for some time after power was connected (please note headspeed), yet airspeed was active before rotor was turning.

Just some minor debugging of my setup and I should be set. Is it possible to roll back my SW and FW to the latest official releases? ( I believe I have beta versions from your site).

Thanks for your help!
Last edited by blueviewlaguna; Jun 01, 2008 at 09:12 PM.
Jun 01, 2008, 10:30 PM
Registered User
Here are some high speed (86 mph peak) runs made after my post above to help diagnose the airspeed sensor - seems to have a floor of 44 mph (first part) and 46 (second part) for some reason. Note the Square wave pattern, seems to indicate something electronic (digital) is affecting it (I would think drift or propwash could not have the well defined square wave pattern).

I never saw this square wave noise-floor pattern until the firmware update (spikes before).

I am looking forward to fine tuning my FDR setup! - it was great looking at the power panel after each flight!
Last edited by blueviewlaguna; Jun 01, 2008 at 10:35 PM.
Jun 02, 2008, 12:15 PM
billpa's Avatar

Sorry to hear about your issues. I want to collect some more data from you. Could you email me at support2@eagletreesystems.com?


Bill, for Eagle Tree
Jun 02, 2008, 05:02 PM
Registered User
Originally Posted by billpa

Sorry to hear about your issues. I want to collect some more data from you. Could you email me at support2@eagletreesystems.com?


Bill, for Eagle Tree
E-mail with FDR sent, thanks for your support.

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