---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Fri 04/23/21: 17 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:38 AM - Re: Cruise speed data for Monowheel with 912ULS (n7188u) 2. 09:29 AM - Re: Re: Cruise speed data for Monowheel with 912ULS (Pete) 3. 10:22 AM - Populated Instrument Module weight (rparigoris) 4. 12:13 PM - Re: Cruise speed data for Monowheel with 912ULS (n7188u) 5. 12:16 PM - CKT exhaust header tube needed, please. (JonathanMilbank) 6. 12:53 PM - Re: Populated Instrument Module weight (n7188u) 7. 01:23 PM - Re: Re: Rotax 912ULS Low Fuel Pressure (Jeffrey Williams) 8. 01:27 PM - Re: Populated Instrument Module weight (D McFadyean) 9. 01:42 PM - Re: Re: Rotax 912ULS Low Fuel Pressure (Pete Zut) 10. 03:24 PM - Re: Re: Cruise speed data for Monowheel with 912ULS (Pete) 11. 03:26 PM - Re: Re: Cruise speed data for Monowheel with 912ULS (Pete) 12. 04:20 PM - Re: Cruise speed data for Monowheel with 912ULS (Griffo) 13. 06:58 PM - Re: CKT exhaust header tube needed, please. (Bud Yerly) 14. 07:52 PM - Re: Re: Cruise speed data for Monowheel with 912ULS (Bud Yerly) 15. 08:06 PM - Re: Cruise speed data for Monowheel with 912ULS (Peter pender) 16. 09:10 PM - Re: Cruise speed data for Monowheel with 912ULS (Griffo) 17. 09:15 PM - Re: Cruise speed data for Monowheel with 912ULS (n7188u) ________________________________ Message 1 _____________________________________ Time: 08:38:12 AM PST US Subject: Europa-List: Re: Cruise speed data for Monowheel with 912ULS From: "n7188u" First let me apologize to the group for trying to dig so deep into this subject. I am by no means an expert but I have been around a bit. However, my goal is to learn and as an Engineer I do tend to overthink stuff a little (good thing when you design life critical medical devices :) ). Griffo, this subject is so complex, and open to so much debate that yes, what you mention is valid, but a few items beg to be clarified as to ensure we are comparing apples to apples. First, RPM alone is not enough to determine the power output of an engine (although you mention speed which could be used as the additional parameter but I prefer not to due to variability). You need a way to determine that the pitch in your prop is set correctly to start with (and hence the engine is developing the desired power). A common way to "communicate" this to aircraft builders is through the "static RPM" parameter. But, although a good starting point for first flight, the final outcome is so dependent on the prop design that the parameter alone is not enough to properly set a ground adjustable prop. And yes, the "art" of adjusting a fixed pitch prop will always depend on the preference of the user so is there really a "right" answer?, certainly not. Keep in mind though that the Europa, as well as my LongEZ, ire aircrafts designed for speed so it is my goal to maximize speed and still retain acceptable TO performance. Also, the engine operates most of the time in cruise regime, so to achieve descent efficiency it is desirable to operate at power/RPM settings that avoids "chocking" the engine with low throttle settings. The consensus I found in the Rotax-Owners forums that made most sense to me is to adjust the prop pitch so that you get 5800 RPM WOT in the air at level flight (of course this would be altitude and temp dependent). Then check RPM on takeoff to make sure it will still provide acceptable takeoff and climb performance. If you set your prop with that specific baseline then yes the MAP info is unnecessary for comparison purposes but only if everyone does it that way (unlikely). BTW, I have spoken to CTLS owners in my field and they agree that 4900 to 5000 RPM on initial climb is customary. As soon as you go to cruise climb speeds that number goes up significantly. If you don't do that the cruise performance will be dismal. They still get impressive TO performance and keep in mind that you are operating at that lower RPM high torque regime for a very short period of time. My LongEZ gives me only 2200 RPM on initial rollout (totally unacceptable per Rutan) but goes up to 2500 by the time I am rotating. On cruise I have to live with 2700 with my throttle lever at around 1/4 open (100 RPM less than redline) which is not great. So is the nature of the beast. In the LongEZ I play with altitude to achieve optimal RPM. Yes, altitude is my VP control :) But that works on a prop that is slightly overpitched. Right now , on my Europa, I am getting around 5300 RPM/80 knts @ WOT on climb but WOT at level flight still exceeds 5800 RPM. At cruise, I checked today, I am at 5200 RPM/22" MAP at 3000' but only truing 115 ktas. I think based on this I still need more pitch. BTW, Bud Yerly told me my airplane will be slow since I still don't have my final shiny coat of paint. I believe him. Of course I can keep tweaking the blade angle until I reach a good compromise (and ultimately that will be the process) but with just a little feedback from the group I can then compare the performance of my airplane to other folks flying the Europa out there. Best Regards, Chris Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501478#501478 ________________________________ Message 2 _____________________________________ Time: 09:29:02 AM PST US From: Pete Subject: Re: Europa-List: Re: Cruise speed data for Monowheel with 912ULS Fwiw, my mono classic with the short but wide warpdrive has the same expected issue: If set to keep it above 5300 static and in the climb (to reduce gearbox/spline abuse), then my cruise is also slow. To get good cruise, I end up pitching to around 5000 static.... which isnt good for the gearbox. My Classic really needs a CS prop to be able to get book cruise numbers. Once I have it back in the air (2 months maybe), Ill get some fresh numbers to share. Cheers, PeteZ > On Apr 23, 2021, at 11:45 AM, n7188u wrote: > > > First let me apologize to the group for trying to dig so deep into this subject. I am by no means an expert but I have been around a bit. However, my goal is to learn and as an Engineer I do tend to overthink stuff a little (good thing when you design life critical medical devices :) ). > > Griffo, this subject is so complex, and open to so much debate that yes, what you mention is valid, but a few items beg to be clarified as to ensure we are comparing apples to apples. > > First, RPM alone is not enough to determine the power output of an engine (although you mention speed which could be used as the additional parameter but I prefer not to due to variability). You need a way to determine that the pitch in your prop is set correctly to start with (and hence the engine is developing the desired power). A common way to "communicate" this to aircraft builders is through the "static RPM" parameter. But, although a good starting point for first flight, the final outcome is so dependent on the prop design that the parameter alone is not enough to properly set a ground adjustable prop. > > And yes, the "art" of adjusting a fixed pitch prop will always depend on the preference of the user so is there really a "right" answer?, certainly not. Keep in mind though that the Europa, as well as my LongEZ, ire aircrafts designed for speed so it is my goal to maximize speed and still retain acceptable TO performance. Also, the engine operates most of the time in cruise regime, so to achieve descent efficiency it is desirable to operate at power/RPM settings that avoids "chocking" the engine with low throttle settings. > > The consensus I found in the Rotax-Owners forums that made most sense to me is to adjust the prop pitch so that you get 5800 RPM WOT in the air at level flight (of course this would be altitude and temp dependent). Then check RPM on takeoff to make sure it will still provide acceptable takeoff and climb performance. If you set your prop with that specific baseline then yes the MAP info is unnecessary for comparison purposes but only if everyone does it that way (unlikely). > > BTW, I have spoken to CTLS owners in my field and they agree that 4900 to 5000 RPM on initial climb is customary. As soon as you go to cruise climb speeds that number goes up significantly. If you don't do that the cruise performance will be dismal. They still get impressive TO performance and keep in mind that you are operating at that lower RPM high torque regime for a very short period of time. My LongEZ gives me only 2200 RPM on initial rollout (totally unacceptable per Rutan) but goes up to 2500 by the time I am rotating. On cruise I have to live with 2700 with my throttle lever at around 1/4 open (100 RPM less than redline) which is not great. So is the nature of the beast. In the LongEZ I play with altitude to achieve optimal RPM. Yes, altitude is my VP control :) But that works on a prop that is slightly overpitched. > > Right now , on my Europa, I am getting around 5300 RPM/80 knts @ WOT on climb but WOT at level flight still exceeds 5800 RPM. At cruise, I checked today, I am at 5200 RPM/22" MAP at 3000' but only truing 115 ktas. I think based on this I still need more pitch. BTW, Bud Yerly told me my airplane will be slow since I still don't have my final shiny coat of paint. I believe him. > > Of course I can keep tweaking the blade angle until I reach a good compromise (and ultimately that will be the process) but with just a little feedback from the group I can then compare the performance of my airplane to other folks flying the Europa out there. > > Best Regards, > Chris > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=501478#501478 > > > > > > > > > ________________________________ Message 3 _____________________________________ Time: 10:22:06 AM PST US Subject: Europa-List: Populated Instrument Module weight From: "rparigoris" Hi Group Curiosity question: Whats the weight of your Populated Instrument Module, and what do you have in it? I know some have went on a weight reduction mission, before and after results would be of interest. Thx. Ron P. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501480#501480 ________________________________ Message 4 _____________________________________ Time: 12:13:42 PM PST US Subject: Europa-List: Re: Cruise speed data for Monowheel with 912ULS From: "n7188u" Thanks PeteZ and I think we are starting to get a great conversation going. First: I don't think you should fixate on the static RPM number, it's meaningless as long as the TO performance is acceptable and you are not overloading the engine during climb. See the blurb I added at the end of this posting regarding the CTLS. They call in their manual that once RPM reaches 4800 during TO roll power is acceptable for takeoff. Second: I am using a Woodcomp Klassic prop that came out of a Sport Cruiser (same engine I have). I have the maintenance manual for that airplane and it calls for max. 5,000 100 rpm ground static RPM. The CTLS people I talk to confirmed today they climb at 4900-5000 RPM all the time. So lets really see in what context the 5200 RPM recommendation from Rotax comes from (which I am sure is important but is that for continuous operation). BTW, as I was writing this I thought of looking at the CTLS operator manual. Very interesting. RPM during initial TO roll is called to be 4800-5000 RPM. Climb RPM 4800-4900. Prop is set to 5500 RPM at WOT in level flight and 4800 RPM recommended for cruise. WOT static RPM 4900. This is from Flight Design USA web site. As the owner of a LongEZ I quickly learned that TO performance must be compromised in order to achieve the speed potential of the airplane (which is still hard to do). So yes, my takeoff run is longer than if I had finer pitch in the prop but it must be done to keep the RPM at bay during cruise (I would have to bring the throttle to idle to not overspeed the prop on that airplane). Yes, the Europa is that kind of airplane that really needs a constant speed prop but if you don't have one it is not the end of the world. At least me, I don't have the $10K needed to put one on mine. BTW, if your thing is to fly from short unimproved runways then of course set your prop for that environment. Best, Chris Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501481#501481 ________________________________ Message 5 _____________________________________ Time: 12:16:55 PM PST US Subject: Europa-List: CKT exhaust header tube needed, please. From: "JonathanMilbank" Today while approaching to land and after landing, the engine sounded quite a lot different. After removing the cowls, the header tube for right rear #3 cylinder was seen to have cracked circumferentially completely around. Rather than weld the two parts back together and end up finding further cracking due to the weld, I'd rather just replace the tube with one that is whole. The carburettors are maintained well balanced with a CarbMate electronic balancer and the Airmaster propeller runs nice and smooth as well. This crack has appeared after more than 4 years in service, so I'm not dissatisfied. Thanks, Jonathan G-EIKY Classic tri-gear Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501482#501482 ________________________________ Message 6 _____________________________________ Time: 12:53:49 PM PST US Subject: Europa-List: Re: Populated Instrument Module weight From: "n7188u" Ron, When I pull my panel off for transponder install in the next couple of weeks I will let you know what mine is. I have a bunch of old school stuff so doubt it will be very light but who knows (or that it would be appealing to many pilots out there). The transponder I'm sure will add a lot percentage wise. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501483#501483 ________________________________ Message 7 _____________________________________ Time: 01:23:29 PM PST US From: Jeffrey Williams Subject: Re: Europa-List: Re: Rotax 912ULS Low Fuel Pressure This has caused me to think a bit. The Europa builder=99s manual shows the fuel going from the fuel selector to the electric fuel pump and then to the engine=99s mechanical fuel pump. Is that how it is set up? If so, does the fuel get pulled through the electric fuel pump by the mechanical fuel pump when the electrical fuel pump is turned off? That seems like it would cause variation at that point. Various aircraft builder=99s books from the EAA show a parallel system for low-wing aircraft. Those diagrams make sense to me. In other words, they show the fuel being provided by a parallel fuel system, with fuel lines going from the fuel selector to both 1) the electric fuel pump and then to the carb, and 2) to the engine=99s mechanical fuel pump and to the carb. That way, if the mechanical pump quits, the electrical pump doesn=99 t have to try to push fuel though the mechanical one to get to the carb. And, the mechanical pump doesn=99t have to pull fuel through the electric fuel pump if the electric fuel pump is off or it quits. Which way should this be set up, and and if you think it=99s the way shown in the Europa builder=99s manual, why? Jeff Williams Builder A157 > On Apr 22, 2021, at 10:19 PM, Griffo wrote: > > > Hi Dave, > > Hi, > > It=C3=A2=C2=C2=99s good that you are taking precautions to avoid having the electric (boost/back up) pump mask/hide a failed mechanical fuel pump. > However, I would question the merit of leaving your electric pump on at all times, as I would expect a pump, so operated, to become a service item replaced at ?? hours of operation (as the mechanical pump has a recommended service life). > I only use my electric pump =C3=A2=C2=C2=93 prior to engine start (off for start) to check fuel pressure/availability. On again, for take-off. Off when safe height above terrain achieved. On again, when downwind for landing. > Your engine will run perfectly without the need for the electric pump, which should only be used when you have a mechanical fuel pump failure, at critical times, when fuel starvation is not a good option. > > -------- > 46 > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=501476#501476 > > > > > > > > > ________________________________ Message 8 _____________________________________ Time: 01:27:26 PM PST US From: D McFadyean Subject: Re: Europa-List: Populated Instrument Module weight 20lbs with txpndr and radio. No horizon, no DI. Analogue. Duncan McF. > On 23 April 2021 at 18:21 rparigoris wrote: > > > > Hi Group > Curiosity question: Whats the weight of your Populated Instrument Module, and what do you have in it? > I know some have went on a weight reduction mission, before and after results would be of interest. > Thx. Ron P. > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=501480#501480 > > > > > > > > > ________________________________ Message 9 _____________________________________ Time: 01:42:57 PM PST US From: Pete Zut Subject: Re: Europa-List: Re: Rotax 912ULS Low Fuel Pressure Fwiw, mine was pulling through the elec fuel pump, but I have re-hosed it and now added an andair checkvalve in parallel with the pump. Common practice, and removes any fuel pump restriction. Will be interesting to see if that change reduces the drop. Cheers PeteZ On Fri., Apr. 23, 2021, 4:30 p.m. Jeffrey Williams, < jeffwill55@sbcglobal.net> wrote: > This has caused me to think a bit. > > The Europa builder=99s manual shows the fuel going from the fuel se lector to > the electric fuel pump and then to the engine=99s mechanical fuel p ump. Is > that how it is set up? > > If so, does the fuel get pulled through the electric fuel pump by the > mechanical fuel pump when the electrical fuel pump is turned off? That > seems like it would cause variation at that point. > > Various aircraft builder=99s books from the EAA show a parallel sys tem for > low-wing aircraft. Those diagrams make sense to me. In other words, they > show the fuel being provided by a parallel fuel system, with fuel lines > going from the fuel selector to both 1) the electric fuel pump and then t o > the carb, *and * 2) to the engine=99s mechanical fuel pump and to t he carb. > > That way, if the mechanical pump quits, the electrical pump doesn =99t have > to try to push fuel though the mechanical one to get to the carb. And, th e > mechanical pump doesn=99t have to pull fuel through the electric fu el pump if > the electric fuel pump is off or it quits. > > Which way *should* this be set up, and and if you think it=99s the way > shown in the Europa builder=99s manual, why? > > Jeff Williams > Builder A157 > > > On Apr 22, 2021, at 10:19 PM, Griffo wrote: > > > Hi Dave, > > Hi, > > It=C3=A2=82=AC=84=A2s good that you are taking precautions to avoid having the electric > (boost/back up) pump mask/hide a failed mechanical fuel pump. > However, I would question the merit of leaving your electric pump on at > all times, as I would expect a pump, so operated, to become a service ite m > replaced at ?? hours of operation (as the mechanical pump has a recommend ed > service life). > I only use my electric pump =C3=A2=82=AC=9C prior to engine star t (off for start) to > check fuel pressure/availability. On again, for take-off. Off when safe > height above terrain achieved. On again, when downwind for landing. > Your engine will run perfectly without the need for the electric pump, > which should only be used when you have a mechanical fuel pump failure, a t > critical times, when fuel starvation is not a good option. > > -------- > 46 > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=501476#501476 > > ________________________________ Message 10 ____________________________________ Time: 03:24:26 PM PST US From: Pete Subject: Re: Europa-List: Re: Cruise speed data for Monowheel with 912ULS Wow that is low. Our local authorized Rotax service guy would shake his head, and show me the chewed customer splined shafts he has on his shelf. :-) Petez > On Apr 23, 2021, at 3:22 PM, n7188u wrote: > > > Thanks PeteZ and I think we are starting to get a great conversation going. > > First: I don't think you should fixate on the static RPM number, it's meaningless as long as the TO performance is acceptable and you are not overloading the engine during climb. See the blurb I added at the end of this posting regarding the CTLS. They call in their manual that once RPM reaches 4800 during TO roll power is acceptable for takeoff. > > Second: I am using a Woodcomp Klassic prop that came out of a Sport Cruiser (same engine I have). I have the maintenance manual for that airplane and it calls for max. 5,000 100 rpm ground static RPM. The CTLS people I talk to confirmed today they climb at 4900-5000 RPM all the time. So lets really see in what context the 5200 RPM recommendation from Rotax comes from (which I am sure is important but is that for continuous operation). > > BTW, as I was writing this I thought of looking at the CTLS operator manual. Very interesting. RPM during initial TO roll is called to be 4800-5000 RPM. Climb RPM 4800-4900. Prop is set to 5500 RPM at WOT in level flight and 4800 RPM recommended for cruise. WOT static RPM 4900. This is from Flight Design USA web site. > > As the owner of a LongEZ I quickly learned that TO performance must be compromised in order to achieve the speed potential of the airplane (which is still hard to do). So yes, my takeoff run is longer than if I had finer pitch in the prop but it must be done to keep the RPM at bay during cruise (I would have to bring the throttle to idle to not overspeed the prop on that airplane). Yes, the Europa is that kind of airplane that really needs a constant speed prop but if you don't have one it is not the end of the world. At least me, I don't have the $10K needed to put one on mine. > > BTW, if your thing is to fly from short unimproved runways then of course set your prop for that environment. > > Best, > Chris > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=501481#501481 > > > > > > > > > ________________________________ Message 11 ____________________________________ Time: 03:26:16 PM PST US From: Pete Subject: Re: Europa-List: Re: Cruise speed data for Monowheel with 912ULS Forget to ask: 80? or high compression 100hp? (Might be less of an issue on the 80) > On Apr 23, 2021, at 3:22 PM, n7188u wrote: > > > Thanks PeteZ and I think we are starting to get a great conversation going. > > First: I don't think you should fixate on the static RPM number, it's meaningless as long as the TO performance is acceptable and you are not overloading the engine during climb. See the blurb I added at the end of this posting regarding the CTLS. They call in their manual that once RPM reaches 4800 during TO roll power is acceptable for takeoff. > > Second: I am using a Woodcomp Klassic prop that came out of a Sport Cruiser (same engine I have). I have the maintenance manual for that airplane and it calls for max. 5,000 100 rpm ground static RPM. The CTLS people I talk to confirmed today they climb at 4900-5000 RPM all the time. So lets really see in what context the 5200 RPM recommendation from Rotax comes from (which I am sure is important but is that for continuous operation). > > BTW, as I was writing this I thought of looking at the CTLS operator manual. Very interesting. RPM during initial TO roll is called to be 4800-5000 RPM. Climb RPM 4800-4900. Prop is set to 5500 RPM at WOT in level flight and 4800 RPM recommended for cruise. WOT static RPM 4900. This is from Flight Design USA web site. > > As the owner of a LongEZ I quickly learned that TO performance must be compromised in order to achieve the speed potential of the airplane (which is still hard to do). So yes, my takeoff run is longer than if I had finer pitch in the prop but it must be done to keep the RPM at bay during cruise (I would have to bring the throttle to idle to not overspeed the prop on that airplane). Yes, the Europa is that kind of airplane that really needs a constant speed prop but if you don't have one it is not the end of the world. At least me, I don't have the $10K needed to put one on mine. > > BTW, if your thing is to fly from short unimproved runways then of course set your prop for that environment. > > Best, > Chris > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=501481#501481 > > > > > > > > > ________________________________ Message 12 ____________________________________ Time: 04:20:03 PM PST US Subject: Europa-List: Re: Cruise speed data for Monowheel with 912ULS From: "Griffo" Word of caution; Its my opinion that airframe/propeller manufacturers want to optimise sales (particularly in the highly competitive sport aircraft market). They will happily compromise engine servile life to do this. On the other hand, engine manufactures (Rotax) want to preserve the service life of the engine and will set perimeters that have a good chance of achieving this. Again, in my opinion, the (Rotax) engine operating perimeters should transcend anything being put out by the airframe or propeller manufacturers. Follow the Rotax recommendations for static and max rpm time limits. Set your engine to work between these limits and you wont go far wrong. If this does not meet your operational requirements - invest in an in flight adjustable propeller. -------- 46 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501489#501489 ________________________________ Message 13 ____________________________________ Time: 06:58:24 PM PST US From: Bud Yerly Subject: RE: Europa-List: CKT exhaust header tube needed, please. If you have an older CKT there were some weld issues. The 912S is a rougher engine and the exhaust system will shake. If the crack was near the spring attachment it is a weld problem. Another issue is drilling of EGT holes. Stress risers happen. If the muffler is hitting the frame the down tube can be stressed in bending and crack. Wrong kinds of springs can be a problem also, but the springs break before the tube normally. Sometimes we just don't know. Contact Robin at CKT. They will take care of you. Best Regards, Bud Yerly -----Original Message----- From: owner-europa-list-server@matronics.com On Behalf Of JonathanMilbank Sent: Friday, April 23, 2021 3:17 PM Subject: Europa-List: CKT exhaust header tube needed, please. Today while approaching to land and after landing, the engine sounded quite a lot different. After removing the cowls, the header tube for right rear #3 cylinder was seen to have cracked circumferentially completely around. Rather than weld the two parts back together and end up finding further cracking due to the weld, I'd rather just replace the tube with one that is whole. The carburettors are maintained well balanced with a CarbMate electronic balancer and the Airmaster propeller runs nice and smooth as well. This crack has appeared after more than 4 years in service, so I'm not dissatisfied. Thanks, Jonathan G-EIKY Classic tri-gear Read this topic online here: https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fforums.matronics.com%2Fviewtopic.php%3Fp%3D501482%23501482&data=04%7C01%7C%7C723bf5ea007e4d530fa008d9068cf220%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637548024686986801%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=KA7EOn0gDXq3Dsaw%2FR8oJCpxSqZJl08MmBQldMbhVC4%3D&reserved=0 ________________________________ Message 14 ____________________________________ Time: 07:52:21 PM PST US From: Bud Yerly Subject: RE: Europa-List: Re: Cruise speed data for Monowheel with 912ULS Guys, The main problem with playing with pitch on the propeller is one never wants to overload or lug the engine on takeoff. See Rotax SL 912-16R1 which states to set WOT for takeoff no lower than 5200 on the 912 and 912S/914 with specified fuel octanes. Reason is detonation. If you run high quality gas 5200 Static WOT pretty much assures you that detonation is unlikely. Since detonation is destructive and at 5000 RPM can't be detected by ear easily and the engine has no knock sensor, it is probably a good idea not to lug the engine down below that. Aircraft manufacturers are interesting. To tout the top speed of an aircraft a fixed pitch is set to 4000 for WOT takeoff. Needless to say one can check the Rotax Operational charts and that is at the limit of the propellers capability and frankly beyond the edge of possible detonation, but at 7500 feet MSL the cruise speed is decent so it is put in the brochure. For takeoff distance, the aircraft manufacturer sets 5650 and gets spectacularly short takeoffs. Of course, immediately after liftoff the engine is at 5800 RPM and the throttle is ripped back to prevent an overspeed. Manufacturers are interested in airplane sales. You will not get the exact performance of the book normally. It is prudent to set 5200 for auto gas operations especially where octane ratings may be suspect. In test flying to get the best from your aircraft the test pilot must fly boring short flights at differing prop settings to get the best all around prop setting. For me that was 5000 RPM on AvGas WOT Static. I got 5500 at 90 Kts climb, 5000 at cruise at 134Kts. In a 900 pound APS or empty wt. trigear. Clean composite aircraft will run out of prop with a fixed pitch almost all the time. You will have to live with reducing the power to maintain 5000 RPM for cruise or run around like the LSAs at higher RPMs trying to get somewhere. Performance testing requires repetitive tests at specific RPM, MP, FF, Altitude and weight. Make a spreadsheet and note the prop pitch for the test, fuel type, WOT static indications, TO roll, Climb speed to get 5500 exactly, and log the RPM, Throttle position, MP, FF, at each cruise altitude. Land and tweak the prop and go fly again compensating for the altitude change as the temp changes to maintain roughly the same density. SPREADSHEETS TELL THE STORY! Don't go cheap on fuel. I have tested an 80 HP KR at 4000 RPM WOT on AvGas and the takeoff was less than spectacular. Over a 1000 foot takeoff roll. Float in the landing was so bad shutting the engine off is preferred on a hot day. 10,000 foot speed was quite impressive. If I recall that little KR2 went nearly 138 Knots on a fixed Warp Drive tapered blade. (Cold day!) Never did that again. Most of that planes life was done at 5000 RPM WOT Static. Speed dropped only about 10 knots but you could get off the ground in 800 feet and land on a 3000 foot runway and turn off at mid field without shutting off the engine. I prefer to spend the bucks and install a constant speed prop on composite aircraft. You get the best takeoff distance, climb rate and best cruise your engine can provide. I still don't do Max Continuous at altitude with the 914. I stick with my charts and look for the best range, max endurance, or time to destination I can get. My little Europa responds. On 912S equipped aircraft, fuel flow does not decrease with altitude above roughly 3500 MSL. So, either a leaning kit is needed or at WOT your gas milage tends to sag, so setting the throttle slightly back and or adding a leaning kit increases performance and range slightly. On a 912S ram air is not normally a good idea. It tends to lean the engine excessively rather than add MP. The typical Bing is designed to suck air, that is why the Bing 64 on the 914 has all those gimmicks to keep the mixture right. Go get some data on your plane. But don't blow the engine doing it. It's expensive and time consuming. Best Regards, Bud Yerly -----Original Message----- From: owner-europa-list-server@matronics.com On Behalf Of n7188u Sent: Friday, April 23, 2021 11:38 AM Subject: Europa-List: Re: Cruise speed data for Monowheel with 912ULS First let me apologize to the group for trying to dig so deep into this subject. I am by no means an expert but I have been around a bit. However, my goal is to learn and as an Engineer I do tend to overthink stuff a little (good thing when you design life critical medical devices :) ). Griffo, this subject is so complex, and open to so much debate that yes, what you mention is valid, but a few items beg to be clarified as to ensure we are comparing apples to apples. First, RPM alone is not enough to determine the power output of an engine (although you mention speed which could be used as the additional parameter but I prefer not to due to variability). You need a way to determine that the pitch in your prop is set correctly to start with (and hence the engine is developing the desired power). A common way to "communicate" this to aircraft builders is through the "static RPM" parameter. But, although a good starting point for first flight, the final outcome is so dependent on the prop design that the parameter alone is not enough to properly set a ground adjustable prop. And yes, the "art" of adjusting a fixed pitch prop will always depend on the preference of the user so is there really a "right" answer?, certainly not. Keep in mind though that the Europa, as well as my LongEZ, ire aircrafts designed for speed so it is my goal to maximize speed and still retain acceptable TO performance. Also, the engine operates most of the time in cruise regime, so to achieve descent efficiency it is desirable to operate at power/RPM settings that avoids "chocking" the engine with low throttle settings. The consensus I found in the Rotax-Owners forums that made most sense to me is to adjust the prop pitch so that you get 5800 RPM WOT in the air at level flight (of course this would be altitude and temp dependent). Then check RPM on takeoff to make sure it will still provide acceptable takeoff and climb performance. If you set your prop with that specific baseline then yes the MAP info is unnecessary for comparison purposes but only if everyone does it that way (unlikely). BTW, I have spoken to CTLS owners in my field and they agree that 4900 to 5000 RPM on initial climb is customary. As soon as you go to cruise climb speeds that number goes up significantly. If you don't do that the cruise performance will be dismal. They still get impressive TO performance and keep in mind that you are operating at that lower RPM high torque regime for a very short period of time. My LongEZ gives me only 2200 RPM on initial rollout (totally unacceptable per Rutan) but goes up to 2500 by the time I am rotating. On cruise I have to live with 2700 with my throttle lever at around 1/4 open (100 RPM less than redline) which is not great. So is the nature of the beast. In the LongEZ I play with altitude to achieve optimal RPM. Yes, altitude is my VP control :) But that works on a prop that is slightly overpitched. Right now , on my Europa, I am getting around 5300 RPM/80 knts @ WOT on climb but WOT at level flight still exceeds 5800 RPM. At cruise, I checked today, I am at 5200 RPM/22" MAP at 3000' but only truing 115 ktas. I think based on this I still need more pitch. BTW, Bud Yerly told me my airplane will be slow since I still don't have my final shiny coat of paint. I believe him. Of course I can keep tweaking the blade angle until I reach a good compromise (and ultimately that will be the process) but with just a little feedback from the group I can then compare the performance of my airplane to other folks flying the Europa out there. Best Regards, Chris Read this topic online here: https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fforums.matronics.com%2Fviewtopic.php%3Fp%3D501478%23501478&data=04%7C01%7C%7C1df5dbba5d174a15e3b008d9066e5159%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637547893148900798%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=bEoHy5XU5%2Fi9OXP%2BmcpbiVEbvDkyK7K8DwfoLYNLPDA%3D&reserved=0 ________________________________ Message 15 ____________________________________ Time: 08:06:48 PM PST US Subject: Europa-List: Re: Cruise speed data for Monowheel with 912ULS From: "Peter pender" Hi Chris, The SL that I referred Griffo to back in your other post states the you should have 5200 rpm min at take off WOT. It doesn't say what part of TO. It also doesn't mention any thing about static revs in regard prop pitch. They now have a sort of power chart as well but once again, pretty vague. Pete is probably correct that it doesn't help the gearbox but I think the main reason is to protect the crankshaft. That SL came out after a crash where an aircraft with an inflight adjustable prop had been operated for some time at too low revs for the MAP. Prior to that most people tried for 4900 to 5000 at TO for a bit of cruise performance and I'm sure a lot of people still do. It's really what ever people feel comfortable with. Cheers Peter Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501494#501494 ________________________________ Message 16 ____________________________________ Time: 09:10:07 PM PST US Subject: Europa-List: Re: Cruise speed data for Monowheel with 912ULS From: "Griffo" Hi Peter, If you have 5200 rpm STATIC, you will get that as soon as you open your throttle, to start the TO run. The rpm will climb as you accelerate, moving up into the 5 min max operating range. If your aircraft/engine is climbing into the no go zone, raise the nose/steepen the climb to control the rpm within safe limits. As you say, its what "people feel comfortable with" unfortunately the engine may not be so comfortable with this arrangement, resulting in problems "down the track". -------- 46 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501495#501495 ________________________________ Message 17 ____________________________________ Time: 09:15:30 PM PST US Subject: Europa-List: Re: Cruise speed data for Monowheel with 912ULS From: "n7188u" I did continue my research (learning was after all the intent of this posting) and found a Rotax SL-912-016 which does state that WOT operation during takeoff should not result in an RPM lower than 5200 RPM. In light of this new factual information I will say please do follow this recommendation. But I will say this openly: I didn't buy a certified airplane, instead I choose to build an experimental Europa and, at least in the US, that means that it is my responsibility to determine what are the operational parameters that will result in safe operation but also in the performance I expected to achieve from this aircraft. Google "LongEZ N295JF" (Race 25) and I think you will understand where I come from. Sadly, we do live in a litigious society and having open discussions in public forums regarding the essence of what experimental aviation is about is dangerous business so I will desist right now from doing that. I will share any factual info I find such as the one presented above or in the previous postings but it is up to each individual to decide what to do with that info. Really sad. But I still would be interested in receiving information regarding RPM/MAP and speed for your 912 ULS monowheel as originally intended. And PeteZ, both the CTLS and the Sport Cruiser are equipped with he 100 HP ULS engine. Best Regards, Chris Martin Read this topic online here: http://forums.matronics.com/viewtopic.php?p=501496#501496 ------------------------------------------------------------------------------------- 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.