---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Wed 04/21/10: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:07 AM - Re: Fuel consumption for the 912S (rampil) 2. 02:03 PM - 914 fuel consumption (rparigoris) 3. 03:17 PM - Re: Re: Why exactly shouldn't you run a 914 without a prop? (Gilles Thesee) ________________________________ Message 1 _____________________________________ Time: 05:07:17 AM PST US Subject: RotaxEngines-List: Re: Fuel consumption for the 912S From: "rampil" Gentlemen, Any rational discussion of fuel flow rate on the Rotax 912 +/- S really requires specifying the altitude at which you are burning the fuel. Twenty three inches and 5000 at 3000 MSL may be 4.6 gal/hr but at 9000' wot with MP=22.6" the FF may be over 7 gph Cheers -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=295074#295074 ________________________________ Message 2 _____________________________________ Time: 02:03:11 PM PST US Subject: RotaxEngines-List: 914 fuel consumption From: "rparigoris" Curiosity question, when flying at lower altitude and lower power settings with a 914 where you are developing 912 type of power, is fuel flow for a given % power setting effected by instead of leaving the TCU on where it is in control of wastegate servo, jog the wastegate servo till it is fully opened, then turn off the TCU? Thx. Ron Parigoris Read this topic online here: http://forums.matronics.com/viewtopic.php?p=295151#295151 ________________________________ Message 3 _____________________________________ Time: 03:17:06 PM PST US From: Gilles Thesee Subject: Re: RotaxEngines-List: Re: Why exactly shouldn't you run a 914 without a prop? Hi Ron, > Lack of differential fuel pressure on take off leads to "running" of the pilot when engine plays mellow song of "silent night". You need between ~ 2 and 5 PSI differential. If low you could get proper fuel flow but on verge of not being able to meet crack pressure of fuel pressure regulator. Problem is if you have full float bowls and begin take off run, you will be in air with perhaps not enough runway to land on when they run out. Also when cruising it gives you a heads up to close at hand failure. Most culprits of low differential pressure is clogged fuel filter or gasculator/s. If you reduce power and can attain 2 PSI then you could probably gain yourself a little more time. At altitude where the pumps have to work hardest are where you will first see lower readings, a lower altitude may allow you to reach airport. Running lean at altitude is a very bad thing to do, fuel flow may be fine at less than 2 PSI, but go too much lower and fuel flow will suffer. Differential ca! > n give you a heads up to problem before it happens. > We made some measurements of fuel pressure/differential pressure vs fuel flow (on the ground). We found interesting things (circulating vapour bubbles, etc...), but there was no measurable delay between change of fuel flow and change of fuel pressure or vice versa. So considering that fuel flow measurements take place with one turbine upstream of the regulator and the other downstream of it, we did not feel compelled to add fuel pressure measurements as both parameters are directly related in this engine. Best regards, -- Gilles http://contrails.free.fr ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rotaxengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RotaxEngines-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/rotaxengines-list Browse Digests http://www.matronics.com/digest/rotaxengines-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.