flyrotary@lancaironline.net Mailing List Archive

Hi Dennis, Nice experiment - some useful information for folks to make decisions with concerning size of primary injector in the Renesis. I calculated that at your fuel pressure (assuming the rated flows of the injectors are for 56 psi, I derated the flow 14% for your- 42 psi), that you were getting approx 507 cc/min total fuel flow at 100% from your two 295 cc/min primary injectors. This equates to approx 8.04 gallon/hr which at 6 lb/gal = 48 lbs/hr /0.55 = 87.7 HP. So I do not believe that you were producing 140 HP - but considerably less. The RV can fly 0n 87.7 HP once airborne without any real problem, but I sure would not want to be taking off on anything less than a 5000 ft strip at sea level {:>) This is (in my opinion) sufficient reason by itself to have all four injectors near the same size - or at least have the primary up around 440 cc/min. That would give approx (derated 14% for lower pressure of 42 psi) around 12 gph x 6 = 72 lb/hr/0.55 = 130 HP. That is about what I was making way back in 1998 when I first flew. The RV flies fine (but, you won't hit 200 MPH {:>) - my max was around 185 MPH TAS back then) on that power once airborne, but take off run on a hot day was overly long - probably close to 2000 feet, perhaps more. I do agree with your analysis of the engine leaning out once the injectors hit 100% duty cycle, but believe your power was considerably lower than what you estimated. The average injector flow for injectors shown in the Renesis manual are Red - 294 cc/min Yellow - 360 cc/min Blue - 502 cc/min Their max flow shown was a bit higher but I took the average. I presume you currently have the red primary injectors and blue secondary??? Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Dennis Haverlah Sent: Wednesday, June 24, 2009 12:26 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: 295cc vs 495 cc Renesis Test[FlyRotary] I've been following the injector thread for a few days so today I tried an experiment. I ran my Renisis with stock injectors (295 Pri and 495 Sec) on the ground to see how it ran with primary or secondary injectors turned off and how much HP I could generate with the 295 cc primaries. Note - My fuel pressure is set at 42 psi. I found I could run around 140 HP ( HP as shown on the Not Calibrated EM-2) with the primaries on and the secondaries off. I also found that as I opened the throttle above the 100 % duty cycle of the primaries the engine would go lean quite rapidly and quit. If I were in take-off mode at low altitude and had a secondary injector fail I don't believe I could diagnose the problem easily and keep the engine running on the primaries!! My theory as to why the engien quits is that as I am running only on the primaries and I advance the throttle beyond the point where the primaries are at 100% duty cycle the engine starts to go too lean and the RPM's decrease - This causes the MP to increase because the engine is pumping less air. As the MP increases the volumn of air in the combustion chamber increases. You need more fuel to compensate but the injector is already supplying the maximum fuel it is capable of supplying. The fire goes out and the engine quits. I believe to keep the engine running when I have a secondary injector fail I'd need to throttle back to some where around 18 inches MP before turning off the secondaries and figuring out the secondaries are bad. If the engine ran smooth on the primaries I could slowly advance the throttle to increase HP as long as I did not go too high MP and get into the lean condition. This is just too much stuff to do at low level just after take-off!! I now plan on replacing the blue 295 CC primary injectors with yellow 495 CC secondary injectors!! Dennis H. -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com