---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Tue 06/20/17: 10 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:41 AM - Re: RotaxEngines/Bing carb's alleged altitude compensation (rampil) 2. 05:51 AM - Re: Rotax 912 oil analysis (rampil) 3. 06:06 AM - Re: New Cylinder heads temperature sensors and matching Temperat (rampil) 4. 06:10 AM - Re: Variable Oil Pressure Reading (rampil) 5. 06:10 AM - Re: Re: RotaxEngines/Bing carb's alleged altitude compensation (Lowell Fitt) 6. 07:16 AM - Re: Re: Variable Oil Pressure Reading (FLYaDIVE) 7. 07:30 AM - Re: RotaxEngines-List Digest: 1 Msgs - 06/19/17 () 8. 05:57 PM - Re: Variable Oil Pressure Reading (rampil) 9. 06:23 PM - Re: Variable Oil Pressure Reading (JohnF) 10. 07:12 PM - Re: Re: Variable Oil Pressure Reading (FLYaDIVE) ________________________________ Message 1 _____________________________________ Time: 05:41:50 AM PST US Subject: RotaxEngines-List: Re: RotaxEngines/Bing carb's alleged altitude compensation From: "rampil" Interesting that this old canard about altitude compensation is raising it's head from the dead again. It is, basically a false claim, unless, as Creighton points out you restrict your flying to Piper cub altitudes. Fuel consumption, I believe, is most relevant during cross country ops, and during XC ops, I usually plan FL060-090 over the flatlands I now live amidst. As they say, if you plan 500' AGL (1500' MSL here), your mileage may vary! When my Europa was freshly built 13 years ago and my engine fully instrumented, I ran extensive test cards on engine performance while flying off my Phase 1 at Z-Hills. Climbing above 3-4,000 DA, fuel consumption rises reliably, while effective power declines as expected. I published the spreadsheets here on the Matronics forums at the time and shared them with Phil Lockwood. Shortly after that, Rotax stopped advertising this "feature". Coincidence? Perhaps. Rather than theory from possibly commercially informed interests, I would prefer more actual measurements, preferably from disinterested but experienced third parties. If there is confusion about the Bing system, consider the role that Rotax played. Despite the advertising, the official operator's manual provides essentially no performance / consumption data compared with Lyc / Con manuals. I still love my 912s, but I am a bit steamed that my block cracked at 380 hours of operation and despite some discount, my repair bill was over $10k. -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=470260#470260 ________________________________ Message 2 _____________________________________ Time: 05:51:41 AM PST US Subject: RotaxEngines-List: Re: Rotax 912 oil analysis From: "rampil" Oil analysis in Rotax engines is difficult to assess since Rotax refuses to provide either normative data or metallurgical content data for components to use for diagnosis should a particular ion spike. -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=470263#470263 ________________________________ Message 3 _____________________________________ Time: 06:06:55 AM PST US Subject: RotaxEngines-List: Re: New Cylinder heads temperature sensors and matching Temperat From: "rampil" Hugh, It would help to know if the sensors are thermocouple or resistive, for example. All TC type "K" senders (yellow/red) should work with all type K gauges unless the wire length is much different than the gauge expects. Use a VOM to measure the resistance of the probe and compare it to what should be stamped on the back of the gauge. If you have resistance type probes, they usually require a matched set of probe/gauge. -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=470265#470265 ________________________________ Message 4 _____________________________________ Time: 06:10:30 AM PST US Subject: RotaxEngines-List: Re: Variable Oil Pressure Reading From: "rampil" I could be wrong about this, but a small bubble is far more likely to smooth out dynamic swings in pressure than to create them. Think plumbing water hammer arrestor (a pipe length full of air). Do these oil pressure changes depend on oil temperature (as they normally do)? -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=470266#470266 ________________________________ Message 5 _____________________________________ Time: 06:10:51 AM PST US From: Lowell Fitt Subject: Re: RotaxEngines-List: Re: RotaxEngines/Bing carb's alleged altitude compensation Interesting post. My understanding was That the altitude compensation was in fact, related to the Cub altitudes. The memory comes up as we, on our way home from an Idaho Back Country adventure in our Kitfoxes, flying the bends of a river at 100 ft. looking for wildlife and practicing steep turns, we listened to the chatter coming from a group of RVs on their way to the Reno Air Races, while flying at RV altitudes. all the talk was about manifold pressure and airspeed. To each his own, I guess. Lowell On Jun 20, 2017 5:46 AM, "rampil" wrote: > > Interesting that this old canard about altitude compensation is raising > it's head from the dead again. It is, basically a false claim, unless, as > Creighton points out you restrict your flying to Piper cub altitudes. Fuel > consumption, I believe, is most relevant during cross country ops, and > during XC ops, I usually plan FL060-090 over the flatlands I now live > amidst. As they say, if you plan 500' AGL (1500' MSL here), your mileage > may vary! > > When my Europa was freshly built 13 years ago and my engine > fully instrumented, I ran extensive test cards on engine performance > while flying off my Phase 1 at Z-Hills. Climbing above 3-4,000 DA, fuel > consumption rises reliably, while effective power declines as expected. > I published the spreadsheets here on the Matronics forums at the time > and shared them with Phil Lockwood. Shortly after that, Rotax stopped > advertising this "feature". Coincidence? Perhaps. > > Rather than theory from possibly commercially informed interests, > I would prefer more actual measurements, preferably from > disinterested but experienced third parties. If there is confusion about > the Bing system, consider the role that Rotax played. > > Despite the advertising, the official operator's manual provides > essentially no performance / consumption data compared with > Lyc / Con manuals. > > I still love my 912s, but I am a bit steamed that my block cracked at > 380 hours of operation and despite some discount, my repair bill was over > $10k. > > -------- > Ira N224XS > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=470260#470260 > > ________________________________ Message 6 _____________________________________ Time: 07:16:47 AM PST US From: FLYaDIVE Subject: Re: RotaxEngines-List: Re: Variable Oil Pressure Reading Ira: You are correct, you are Wrong! Air, Gases are COMPRESSIBLE! Liquids are NON-COMPRESSIBLE. Liquids will transmit pressure equally in ALL directions and at the same pressure even through different/mixed size hoses. Physics - Fluid Dynamics 101. Air on the other hand is compressible and also expandable and will expand and compress CHANGING its volume and pressure - Boyle's Law also a part of Physics 101. So, the air bubble will cause the transducer and/or the gauge to pulse. Barry On Tue, Jun 20, 2017 at 9:10 AM, rampil wrote: > > I could be wrong about this, but a small bubble is far more likely > to smooth out dynamic swings in pressure than to create them. Think > plumbing water hammer arrestor (a pipe length full of air). > > Do these oil pressure changes depend on oil temperature (as they normally > do)? > > -------- > Ira N224XS > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=470266#470266 > > ________________________________ Message 7 _____________________________________ Time: 07:30:44 AM PST US From: Subject: RotaxEngines-List: Re: RotaxEngines-List Digest: 1 Msgs - 06/19/17 John F, Once you break open the oil system (such as to replace oil hoses) on a Rotax Engine you introduce the possibility of entrapped air if you do not vent or "purge" the system after refilling the system with new oil per the Rotax instructions in their engine installation manual. You should not operate the engine until the system has been vented. See instructions on page 36 of the installation manual Edition 2 of 1997 03 26 or later editions. Hugh G. McKay III, P.E. Fellow, L.M. ASCE Senior Consultant Worldwide Engineering Inc. 4090 North NC Hwy. 16 Denver, NC 28037 Ph. 704-661-8271 Fax 704-483-5466 email hgmckay@bellsouth.net http://www.wwegeo.com -----Original Message----- From: RotaxEngines-List Digest Server Sent: Tuesday, June 20, 2017 3:03 AM Subject: RotaxEngines-List Digest: 1 Msgs - 06/19/17 * ================================================= Online Versions of Today's List Digest Archive ================================================= Today's complete RotaxEngines-List Digest can also be found in either of the two Web Links listed below. The .html file includes the Digest formatted in HTML for viewing with a web browser and features Hyperlinked Indexes and Message Navigation. The .txt file includes the plain ASCII version of the RotaxEngines-List Digest and can be viewed with a generic text editor such as Notepad or with a web browser. HTML Version: http://www.matronics.com/digest/digestview.php?Style=82701&View=html&Chapter 17-06-19&Archive=RotaxEngines Text Version: http://www.matronics.com/digest/digestview.php?Style=82701&View=txt&Chapter 17-06-19&Archive=RotaxEngines =============================================== EMail Version of Today's List Digest Archive =============================================== ---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Mon 06/19/17: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:35 PM - Variable Oil Pressure Reading (JohnF) ________________________________ Message 1 _____________________________________ Time: 06:35:58 PM PST US Subject: RotaxEngines-List: Variable Oil Pressure Reading From: "JohnF" I just changed the oil lines on the Rotax in my RV-12 and now see oil pressure varying from 33 psi to 60 psi. I moves around like that in flight. I wonder if air is in the oil line to the oil pressure sensor...if so how to check and bleed it out since it goes to a 'dead-end' at the sensor. Best I can think of is to open that line and let oil run out and quickly replace the oil line to the sensor in the hope that the air bubble will be gone Your ideas? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=470251#470251 ________________________________ Message 8 _____________________________________ Time: 05:57:45 PM PST US Subject: RotaxEngines-List: Re: Variable Oil Pressure Reading From: "rampil" Hey Barry, You are right about the static situation, it's a bit different dynamically. Back in the day when I used to teach about the fluid dynamics of invasive arterial blood pressure, I would note that the distortion or "ringing" in the system was related to the resonance of the system which in turn is a function of the compliance of the tubing plus air bubbles, and the inertance of the fluid column. When the driving frequency(pulsation of the oil pump) gets close to the system's resonant frequency, the pressure Oscillates wildly ( in a measurement system that has adequate frequency response). I will generalize (and guess) a bit to say that 1) the driving frequency of the oil pump, a multiple of RPM is way higher than the responsiveness of mechanical Oil pressure gauges to track the waveform even though you would be able to see the ringing with an electronic transducer and an o-scope. 2) air (increasing compliance) decreases the resonant freq of the tubing system thus reducing the apparent Oscillation on the gauge by pushing the resonant frequency of the tubing well below the rpm harmonic. -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=470292#470292 ________________________________ Message 9 _____________________________________ Time: 06:23:42 PM PST US Subject: RotaxEngines-List: Re: Variable Oil Pressure Reading From: "JohnF" I am the OP....I suspect I have found the problem and will know tomorrow when I button up the plane and do a run up or perhaps a short flight. I will post my results. I doubt that it will involve anything very exotic, but we'll see. JohnF Read this topic online here: http://forums.matronics.com/viewtopic.php?p=470295#470295 ________________________________ Message 10 ____________________________________ Time: 07:12:22 PM PST US From: FLYaDIVE Subject: Re: RotaxEngines-List: Re: Variable Oil Pressure Reading Ira: Sorry to say teach, wrong guess! Well, not a guess, just over thinking a simple situation. What about open and closed end resonance of the oil lines? What about cavitation cause by bubbles in a bend, or the reduced flow especially at 90 Deg bends. If you want to prove my reasoning true or disprove yours just add a length of oil line. That will change the 'frequency' as you stated and if you are correct. The pulsing will go away. But, if you are wrong and if the air bubble remains then the problem will continue and your theory is proven wrong. Think of it this way: Why does Rotax make a big deal about 'Burping' the system? Because air bubbles cause all these types of problems. If what you say is true, then there would be hundredths of plane owners complaining about the same problem. Both with and without Rotax engines. Get rid of the air and the problem goes with it! K.I.S.S. M.E.! Barry QA Engineer that punched holes in theories. On Tue, Jun 20, 2017 at 8:57 PM, rampil wrote: > > Hey Barry, > > You are right about the static situation, it's a bit different dynamically. > Back in the day when I used to teach about the fluid dynamics > of invasive arterial blood pressure, I would note that > the distortion or "ringing" in the system was related to the > resonance of the system which in turn is a function of the > compliance of the tubing plus air bubbles, and the inertance > of the fluid column. When the driving frequency(pulsation of the > oil pump) gets close to the system's resonant frequency, the pressure > Oscillates wildly ( in a measurement system that has adequate frequency > response). > > I will generalize (and guess) a bit to say that > 1) the driving frequency of the oil pump, a multiple of RPM > is way higher than the responsiveness of mechanical > Oil pressure gauges to track the waveform even though you > would be able to see the ringing with an electronic transducer > and an o-scope. > 2) air (increasing compliance) decreases the resonant > freq of the tubing system thus reducing the apparent > Oscillation on the gauge by pushing the resonant frequency > of the tubing well below the rpm harmonic. > > -------- > Ira N224XS > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=470292#470292 > > ------------------------------------------------------------------------------------- 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.