---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Thu 06/09/16: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:40 AM - Re: Rotax 914 Airbox / Fuel Pressure Differential (Jan de Jong) ________________________________ Message 1 _____________________________________ Time: 09:40:47 AM PST US Subject: Re: Europa-List: Rotax 914 Airbox / Fuel Pressure Differential From: Jan de Jong I don't believe the differential pressure measurement carburetors vs. airbox will give much of an early warning. By the time the pressure regulator is unable to maintain the small differential pressure the total (forward) flow, in the best case, is already down by more than half (total flow is normally at least twice the 33 l/h maximum carburetor flow, and many more times the actual carburetor flow in most conditions, f.i. in cruise at lower altitudes when fuel consumption is low and turbo pressure is low). I see the differential pressure measurement as a check on the correct operation of the combination: pressure regulator + return line. To get a really early warning of deterioration one would have to constantly measure the performance of all between tank and pressure regulator input; the 2 ingredients are: total flow and total pressure difference between regulator input and tank. A microcontroller would need to learn the reference curve (total flow vs. total pressure difference) when an installation is in "reference condition". A display would show actual total flow as a % of reference total flow at actual total pressure demanded (determined by actual turbo operation). Jos once mentioned that he checked total forward flow (by defeating return flow pulses - or only their inclusion in the flow calculation - don't remember) as part of his before-takeoff checklist. This seems to me a good way to notice at least slow deterioration early (but higher altitudes would sometimes provide an excuse for a somewhat lower total forward flow than expected). But I need to get on with building instead of daydreaming. Jan de Jong ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message europa-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Europa-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/europa-list Browse Digests http://www.matronics.com/digest/europa-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.