zenith members. 

Anyone install Belite fuel probes and have issues with the fuel drain and vent creating either positive or negative pressure effecting the panel readings? If so, can I ask what was your solution? 

Views: 109

Reply to This

Replies to This Discussion

By Belite fuel probe, do you mean the probe that senses fuel level by a solid-state pressure tranducer?  Years ago, I was interested in this system but could never find an instance of a successful installation in an experimental aircraft.  (By successful, I mean relatively accurate fuel quantity indications in flight.) They seem to work pretty well stationary/on the ground and in low speed aircraft such as ultralights where pressurization of the fuel through the vent is minimal, but apparently as airspeed increases in larger aircraft, the effects of positive or negative venting pressure made them "useless," as one Sonex builder reported.

If things have changed and someone has done a successful installation, I'd like to hear about it!

John

N750A

This is the unit in question. 

I installed them and had the same issue on 601HDS with a Rotax 912uls and 2 leading edge wing tanks..  There was so much negative pressure during climb that the diaphragms were actually bent which would change the zero point.  We could recalibrate and they would appear to work until you took off.

Since the gauge was calibrated with static pressure on the tank and during flight the top of the tank was not at static this was causing the variation in the fuel level output.  I bought 2 of the pressure sensors and put them in the static/pitot system so we could get a voltage that was an indication of these pressures.  Don Honabach wrote an arduino program to take the belite pressure and would take into account the plane was climbing and not traveling 100mph.  I installed the vented caps where you could bent a 1/4 tubing extension so the opening was parallel to the flight path.  This was done trying to keep the top of the tank basically at pitot pressure.  This worked better than the stock belite arrangement, but you could still get the angle of climb high enough that the negative pressure would change the zero of the pressure sensor which required reprograming.

So after several months of trying to get them to work, I trashed them.  I intalled the automotive resistance style sensors in the tank.  I also installed a little red cube flow sensor between the tank and the carburetors.  These were wired into an MGL FF2, which is basically a fuel computer.  Since the automotive style sensors aren't really accurate, I use them to check there is no major leak in the fuel system where the fuel is leaking from somewhere but not going through the red cube.  I use the flow totalizer as my source for actual fuel used and fuel remaining.  The red cube is really accurate if you take the time to calibrate it's K-factor.

So the short answer is they work good in a ground based static system, but a system that is moving and changing angles.  At least on a 601HDS, you are trying to measure about 5-6 inches of water change from full to empty.

Jerry

David,  go to forums and under the 601 tab do a search for Belite.  There are a lot of old discussions on the Belite probes.

I have them in my Cruzer it Works great on the ground no use whatsoever once in the air.

Have you tried venting the fuel caps vs the standard below wing drain /vent? 

I have tried both options not much difference basically soon as the air pressure enters the vent top or bottom it just reads full. I use a fuel flow now as a guide in flight but dip my tanks before each flight.

RSS

New from Zenith:

Zenith Planes For Sale 
 

Classified listing for buying or selling your Zenith building or flying related stuff...


Custom Instrument Panels
for your Zenith
:

Custom instrument panels are now available directly from Zenith Aircraft Company exclusively for Zenith builders and owners. Pre-cut panel, Dynon and Garmin avionics, and more.


Custom Upholstery Kits for your Zenith Aircraft:

Zenith Vinyl Upholstery Kits


Zenith Apparel from EAA:


Zenair Floats


Flying On Your Own Wings:
A Complete Guide to Understanding Light Airplane Design, by Chris Heintz


Builder & Pilot Supplies:

How to videos from HomebuiltHELP.com

Developed specifically for Zenith builders (by a builder) these videos on DVD are a great help in building your own kit plane by providing practical hands-on construction information. Visit HomebuiltHelp.com for the latest DVD titles.

Aircraft Insurance:

 
 

West Coast USA:

 
Pro Builder Assistance:

 

Transition training:

Golden Eagle Aviation

Pianosa Flying Farm

Aircraft Spruce & Specialty for all your building and pilot supplies!

© 2021   Created by Zenith.Aero.   Powered by

Badges  |  Report an Issue  |  Terms of Service