---------------------------------------------------------- RotaxEngines-List Digest Archive --- Total Messages Posted Sun 11/02/08: 16 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:14 AM - Re: Re: setting prop pitch (Dave Austin) 2. 05:32 AM - gear box insp. () 3. 05:51 AM - Setting prop pitch (R Holder) 4. 06:06 AM - Re: Changing Coolant (michael baker) 5. 08:28 AM - Re: Setting prop pitch (Duncan & Ami McFadyean) 6. 08:38 AM - Re: Changing Coolant (darinh) 7. 08:42 AM - Re: Rotax Oil Filter (darinh) 8. 09:06 AM - Re: gear box insp. (rampil) 9. 09:25 AM - Re: Re: gear box insp. (John Cox) 10. 03:07 PM - Re: setting prop pitch (Roger Lee) 11. 03:21 PM - Re: gear box insp. (Roger Lee) 12. 03:23 PM - Re: Free Wheeling Prop (pperrynas) 13. 05:49 PM - Re: Re: setting prop pitch (Dave Austin) 14. 06:06 PM - Re: Free Wheeling Prop (Dale Orth) 15. 07:02 PM - Re: gear box insp. (Paul McAllister) 16. 09:44 PM - Re: setting prop pitch (Roger Lee) ________________________________ Message 1 _____________________________________ Time: 04:14:03 AM PST US From: "Dave Austin" Subject: Re: RotaxEngines-List: Re: setting prop pitch Chris Heitz used to recommend cruise at 5500 but I've always used 5300/5400 as that was where the engine runs the smoothest. If you set it up as cruise at 5500, how do you go any faster without over-revving the engine? Dave Austin 601HDS - 912 ________________________________ Message 2 _____________________________________ Time: 05:32:38 AM PST US From: Subject: RotaxEngines-List: gear box insp. Good morning guys, Does anyone know the requirements for the 912 gear box inspection at 600 hrs. ? Someone told us it requires going to a Rotax repair center and costs around 6 or $ 800 ?, and that an A&P can't do it ? Bob Griffin ________________________________ Message 3 _____________________________________ Time: 05:51:19 AM PST US From: R Holder Subject: RotaxEngines-List: Setting prop pitch > Set the prop to 5500 WOT flat and level, but that is > not where you cruise. When the prop is set to 5500 you > benefit from the prop pitch during other times such as > in takeoff with better climb performance, lower > throttle setting for cruise means a little better fuel > economy. If it is set for 5500 and lets say you bounce > up off the runway and you go "oh no I'm going to drop > it in", then when you give it full throttle trying to > save yourself the engine will spin up faster to save > you, compared to, if you had too big a bite of air with > the prop and it had to struggle to spin up. If the prop > is pitched too much you will need to give it more > throttle/fuel to achieve your cruise speed. When it is > set for 5500 you will be able to pull back on the > throttle/less fuel and still cruise at the speed you > want. You will have a higher top end speed, too. Mind > you we are comparing 5500 to your 4800 here. A 700 rpm > gain will make a big difference. I know some that > cruise at 5500 WOT just to cruise. This will cause > extra wear over time. My question is why? Do you need > to get somewhere a few miles per hour faster all the > time? Why wear and tear any extra on the engine than > need be. We want it to be reliable for its 1500 hours > and more. I think you need to stress (I think this is right) that the 5500 WOT is static, on the ground. The rpm for WOT in the cruise will depend on a number of factors. But i would like to ask if anyone has a 912S/ULS with an airmaster prop and a MAP guage _AND_ a fuel flow meter. Could they do an experiment for me ! Chose a specific airspeed (X) at around your normal cruise speed. I would use 115 knots on my plane. Now there are a number of combinations of rpm and MAP that will achieve that airspeed. I use 25 inches and 4600. The experiment is to set different rpms; and for each adjust the MAP so that the airspeed is X (stabilised). Then for each combination of rpm/MAP record the fuel flow - ideally to the tenth of a litre but a tenth of a US gallon would be OK. As the engine must be producing the same horsepower as it is travelling at the same speed for each combination, any variation in the fuel flow is a measure of the efficiency of the engine. If the efficiency is the same for the whole rpm range tested then the fuel flow would be the same. So a "scientific" test will show any variation and maybe there will be an obvious peak to the efficiency - this will be where the fuel flow is least. According to Roger's recent postings the implication is that this peak efficiency rpm/MAP combination will be at or around 5000 rpm. If several people are able to do this, please post results direct to me so that I can collate independently :-) The critical factor here is that the MAP must be adjusted to get the same airspeed (X) for each rpm figure tested. So the results might look like the following at 115 knots 4500 26 15.8 (15.8 would be the litres per hour fuel flow) 4600 25 15.5 4700 24.5 15.5 4800 24 15.3 4900 23.5 15.1 5000 23.1 15.0 <------ B E S T E F F I C I E N C Y 5100 22.8 15.2 O N T H E S E T E S T F I G U R E S 5200 22.4 15.4 5300 22.1 15.5 It would be something to pass the time on your next two hour flight ! And if you had longer, other speeds could also be tried - X+10 and X -10 ! I will ask the wear and tear questions in another mail sometime as many people only answer one question per mail :-) Thanks Richard Holder with an efficiency hat on ! ________________________________ Message 4 _____________________________________ Time: 06:06:44 AM PST US From: michael baker Subject: Re: RotaxEngines-List: Changing Coolant "When you go back to 50/50 you need to lower your max coolant temp to 248F. If you don't have a coolant gauge then watch the CHT temps as they are very close. You never said why you wanted to change? If you don't have a temp issue why change." I have a small leak in the radiator which I am fixing and I thought it would be a good time to change to antifreeze as my summer CHTs were higher than I like them to be. I understand that using antifreeze could lower them 10 to 20 degrees. Thanks for the the replies to my question on coolant. Mike Do not archive ________________________________ Message 5 _____________________________________ Time: 08:28:44 AM PST US From: "Duncan & Ami McFadyean" Subject: Re: RotaxEngines-List: Setting prop pitch Richard, To save you the bother, the maximum efficiency of any engine is at maximum torque speed and WOT. So that will be somewhere between 4800rpm and 5200 rpm for the 'S' (Rotax's figures have varied somewhat over the years on this!). At less than WOT, efficiency falls off anyway and, within limits, there is no point extracting the x% of required power at a higher engine speed than necessary, because there is a price to pay for the additional mechanical losses of that higher speed. Duncan McF. ----- Original Message ----- From: "R Holder" Sent: Sunday, November 02, 2008 1:50 PM Subject: RotaxEngines-List: Setting prop pitch > > >> Set the prop to 5500 WOT flat and level, but that is >> not where you cruise. When the prop is set to 5500 you >> benefit from the prop pitch during other times such as >> in takeoff with better climb performance, lower >> throttle setting for cruise means a little better fuel >> economy. If it is set for 5500 and lets say you bounce >> up off the runway and you go "oh no I'm going to drop >> it in", then when you give it full throttle trying to >> save yourself the engine will spin up faster to save >> you, compared to, if you had too big a bite of air with >> the prop and it had to struggle to spin up. If the prop >> is pitched too much you will need to give it more >> throttle/fuel to achieve your cruise speed. When it is >> set for 5500 you will be able to pull back on the >> throttle/less fuel and still cruise at the speed you >> want. You will have a higher top end speed, too. Mind >> you we are comparing 5500 to your 4800 here. A 700 rpm >> gain will make a big difference. I know some that >> cruise at 5500 WOT just to cruise. This will cause >> extra wear over time. My question is why? Do you need >> to get somewhere a few miles per hour faster all the >> time? Why wear and tear any extra on the engine than >> need be. We want it to be reliable for its 1500 hours >> and more. > > I think you need to stress (I think this is right) that > the 5500 WOT is static, on the ground. The rpm for WOT in > the cruise will depend on a number of factors. > > But i would like to ask if anyone has a 912S/ULS with an > airmaster prop and a MAP guage _AND_ a fuel flow meter. > > Could they do an experiment for me ! Chose a specific > airspeed (X) at around your normal cruise speed. I would > use 115 knots on my plane. > > Now there are a number of combinations of rpm and MAP that > will achieve that airspeed. I use 25 inches and 4600. > > The experiment is to set different rpms; and for each > adjust the MAP so that the airspeed is X (stabilised). > Then for each combination of rpm/MAP record the fuel flow > - ideally to the tenth of a litre but a tenth of a US > gallon would be OK. > > As the engine must be producing the same horsepower as it > is travelling at the same speed for each combination, any > variation in the fuel flow is a measure of the efficiency > of the engine. If the efficiency is the same for the whole > rpm range tested then the fuel flow would be the same. So > a "scientific" test will show any variation and maybe > there will be an obvious peak to the efficiency - this > will be where the fuel flow is least. > > According to Roger's recent postings the implication is > that this peak efficiency rpm/MAP combination will be at > or around 5000 rpm. > > If several people are able to do this, please post results > direct to me so that I can collate independently :-) The > critical factor here is that the MAP must be adjusted to > get the same airspeed (X) for each rpm figure tested. > > So the results might look like the following > > at 115 knots > 4500 26 15.8 (15.8 would be the litres per hour fuel flow) > 4600 25 15.5 > 4700 24.5 15.5 > 4800 24 15.3 > 4900 23.5 15.1 > 5000 23.1 15.0 <------ B E S T E F F I C I E N C Y > 5100 22.8 15.2 O N T H E S E T E S T F I G U R E S > 5200 22.4 15.4 > 5300 22.1 15.5 > > It would be something to pass the time on your next two hour flight ! > > And if you had longer, other speeds could also be tried - X+10 and X -10 ! > > I will ask the wear and tear questions in another mail > sometime as many people only answer one question per mail :-) > > Thanks > > Richard Holder with an efficiency hat on ! > > > ________________________________ Message 6 _____________________________________ Time: 08:38:53 AM PST US Subject: RotaxEngines-List: Re: Changing Coolant From: "darinh" I had temps drop in excess of 50 degrees when changing from Evans to 50/50 glycol-water mix. My EGT dropped even more than that. I am not a fan of the Evans coolant. I know Prestone makes the "Dexcool" antifreeze that states on the jug that it is specifically designed to be used in aluminum systems. -------- Darin Hawkes Series 7 (Phase 1 - Flight Testing) 914 Turbo Kaysville, Utah Read this topic online here: http://forums.matronics.com/viewtopic.php?p=211774#211774 ________________________________ Message 7 _____________________________________ Time: 08:42:31 AM PST US Subject: RotaxEngines-List: Re: Rotax Oil Filter From: "darinh" Pete, The Napa and STP appear to be the same length as the Fram at least when cross referencing to the same filter. Do you have filter numbers for the Napa and STP so I can verify if they will indeed fit? -------- Darin Hawkes Series 7 (Phase 1 - Flight Testing) 914 Turbo Kaysville, Utah Read this topic online here: http://forums.matronics.com/viewtopic.php?p=211775#211775 ________________________________ Message 8 _____________________________________ Time: 09:06:34 AM PST US Subject: RotaxEngines-List: Re: gear box insp. From: "rampil" If you have an experimental airworthiness cert, you or anyone can do the gearbox inspection. It does require some tooling, a press, and it would be unwise to perform without taking one of the rotax courses in which the technique is taught. I recommend Dean's course at Sebring (aerotechnicalinstitute.com) As for price for sending the work out, call your local authorized Rotax repair center. Don't ask here, it varies around the country. -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=211786#211786 ________________________________ Message 9 _____________________________________ Time: 09:25:30 AM PST US Subject: RE: RotaxEngines-List: Re: gear box insp. From: "John Cox" Wow, I wonder about "anyone" can do the inspection. John Cox -----Original Message----- From: owner-rotaxengines-list-server@matronics.com [mailto:owner-rotaxengines-list-server@matronics.com] On Behalf Of rampil Sent: Sunday, November 02, 2008 9:06 AM Subject: RotaxEngines-List: Re: gear box insp. If you have an experimental airworthiness cert, you or anyone can do the gearbox inspection. It does require some tooling, a press, and it would be unwise to perform without taking one of the rotax courses in which the technique is taught. I recommend Dean's course at Sebring (aerotechnicalinstitute.com) As for price for sending the work out, call your local authorized Rotax repair center. Don't ask here, it varies around the country. -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=211786#211786 ________________________________ Message 10 ____________________________________ Time: 03:07:16 PM PST US Subject: RotaxEngines-List: Re: setting prop pitch From: "Roger Lee" See the torque chart attached. (Top One) Max torque is 5000 rpm after that torque goes down and HP climbs. There is no magic here just the best compromise. Set your prop to get 5500 engine rpm at WOT in the air flat and level. At this setting you will have the best setting for you average pilot and plane. Most of us do not need special prop settings like maybe a float plane. This is not hard, don't make it hard. I have a Dynon system and have all the info. -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Service Center 520-574-1080 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=211845#211845 Attachments: http://forums.matronics.com//files/rotax_in_word_161.doc ________________________________ Message 11 ____________________________________ Time: 03:21:08 PM PST US Subject: RotaxEngines-List: Re: gear box insp. From: "Roger Lee" The 600 hr is not the gearbox inspection, but the overload clutch. You can not do this yourself and will only bend your engine mounts. You will need bracing for the engine, a special 5' tool and lever. I hate to say this in writing, but you may want to forgo this if you have no one in your area to do this check, or fly your plane to a distributor, but ask them first if they can handle this inspection.. If you are using 91 octane then you don't need to do this inspection at this time. -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Service Center 520-574-1080 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=211849#211849 ________________________________ Message 12 ____________________________________ Time: 03:23:54 PM PST US Subject: RotaxEngines-List: Re: Free Wheeling Prop From: "pperrynas" Dale, I have a 912ul (about 100hrs time) on a kitfox and have had a similar problem the last 2 days. The first time (11/1) I just hand turned the prop and started getting compression about every 3rd blade and kept this up until I could "burp" the oil tank. I then tried starting again and finally it fired but ran very rough for a few minutes before settling down. Then today (11/2) I hand rotated prop and again..no compression at all..this time I removed spark plugs one at a time and rotated prop and it may have been a coincidence, but after removing the first plug which was the bottom on cylinder number 3 (i think) once again I had compression about every 3rd blade. I went ahead and removed the other spark plugs one at a time, rotated prop and then re-installed plugs and nothing else changed..still compression about every 3rd blade. Spark plugs were fine as they were recently replaced (3hrs). Again, when starting the engine ran rough a couple of minutes but smoothed up to normal (a little quicker today than yesterday). Have you found anything else out about your problem? I really don't think I did anything to correct my problem other than turning the prop over and letting it sit a few minutes? Anybody else with ideas/experiences would be appreciated. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=211851#211851 ________________________________ Message 13 ____________________________________ Time: 05:49:21 PM PST US From: "Dave Austin" Subject: Re: RotaxEngines-List: Re: setting prop pitch Roger, A question remaining is at what altitude do you do the 5500 WOT? Above 5000 ft I use WOT as the max power is down to 75% at that height. There is another factor.. What is the optimum rotational speed of a given propeller? Dave Austin 601HDS - 912 ________________________________ Message 14 ____________________________________ Time: 06:06:27 PM PST US Subject: RotaxEngines-List: Re: Free Wheeling Prop From: "Dale Orth" Hi Guys, I talked to a Rotax mechanic in Phoenix and he said that carbon deposits on the valves can cause the "no compression" effect when hand propping. He recommended using Marvel Mystery Oil to the fuel to remove Carbon deposits. The previous owner of my plane always used auto fuel and the plane sat for long periods with the sludge from auto fuel building up. Since I'm not sure what I'm getting with Auto fuel I decided to use 100LL Avgas, add Mystery oil & change oil & filter every 25 hrs. I'm also adding Decalin to the Avgas. I was also told to run the engine hard for awhile when using Avgas. I'm using Aeroshell Plus 4 oil. The way I see it spending a little more $$$$ for Oil & additives is cheaper than an early Engine Overhaul. I guess time will tell if this works. Dale -------- Dale KitFox 7 Las Vegas, Nv daleorth@embarqmail.com Read this topic online here: http://forums.matronics.com/viewtopic.php?p=211882#211882 ________________________________ Message 15 ____________________________________ Time: 07:02:42 PM PST US From: Paul McAllister Subject: Re: RotaxEngines-List: gear box insp. Hi Bob,=0A=0AI seem to recall when mine came due I sent it to Lockwood. Th ey turned it around in less than a week and I think it was less than a coup le of hundred dollars.=0A=0ARegards, Paul=0A=0A=0A=0A=0A__________________ ______________=0AFrom: "airgriff@surferz.net" =0ATo: rotaxengines-list@matronics.com=0ASent: Sunday, November 2, 2008 8:30:58 AM =0ASubject: RotaxEngines-List: gear box insp.=0A=0A =0AGood morning =0Aguys ,=0ADoes=0Aanyone know the requirements for the 912 gear box inspection at 600 hrs. ?=0ASomeone told us it requires going to a Rotax repair center and costs around 6=0Aor $ 800 ?, and that an A&P can=A2t do it ?=0ABob=0AGriff =========0A=0A=0A=0A ________________________________ Message 16 ____________________________________ Time: 09:44:04 PM PST US Subject: RotaxEngines-List: Re: setting prop pitch From: "Roger Lee" When I set someone's prop so the engine turns 5500 I always ask at what altitude they fly at the majority of the time. (i.e. some say between 1k-3k, some say 7k-9k). This is the altitude you set the prop for. Whatever they fly at the majority of the time and don't worry about the percentage outside your norms. You will have a slightly flatter pitch prop for the guy that flys at 8k-10k over the guy that flys at 1k-2k. You want your engine to be able to run at it's best HP rating and best torque for your normal everyday flying. Mine is set up for 3k-5k in altitude. Remember a ground adjustable prop setup is a compromise trying to get the best performance at a specific setting for all flights. (it can't be made perfect for all scenarios) The props on the market and Mfg's that have props for the Rotax 912's know what the Rotax turns for rpm so set your prop for the correct engine rpm for the best combination. This is also a compromise. Try it, if you don't like it change it back. -------- Roger Lee Tucson, Az. Light Sport Repairman - Maintenance Rated Rotax Service Center 520-574-1080 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=211919#211919 ------------------------------------------------------------------------------------- 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.