---------------------------------------------------------- Europa-List Digest Archive --- Total Messages Posted Sat 03/21/09: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:27 AM - Woodcomp propellors (Richard Lamprey) 2. 03:50 AM - Re: Constant Speed Props & Propeller twist. (David Joyce) 3. 05:55 AM - Re: Constant Speed Props, etc. (Robert Borger) 4. 11:22 AM - Constant Speed Props, etc. (Fred Klein) 5. 12:09 PM - Catto ground adjustable prop for LSA market (glenn crowder) 6. 06:14 PM - Re: Constant Speed Props, etc. (John & Paddy Wigney) 7. 07:06 PM - Re: Catto ground adjustable prop for LSA market (ALAN YERLY) 8. 09:58 PM - Bolly Prop Australia to release high twist blade for LSA market (glenn crowder) 9. 10:55 PM - Re: Bolly Prop Australia to release high twist blade for LSA market (craig bastin) ________________________________ Message 1 _____________________________________ Time: 12:27:31 AM PST US From: "Richard Lamprey" Subject: Europa-List: Woodcomp propellors I have heard reliable reports of Woodcomp propellors shedding blades in flight in South Africa, (and engines hanging by a thread on the bearers). It may be worth looking in to these. Best Richard Europa Classic 5Y-LRY. Kenya ________________________________ Message 2 _____________________________________ Time: 03:50:44 AM PST US From: "David Joyce" Subject: Re: Europa-List: Constant Speed Props & Propeller twist. Fred, The twist of a blade along its length is fairly critical to engine cooling. Changing from a Woodcomp SR2000 with 12 degree twist to an SR3000W with about 26 degrees of twist has transformed my 914 cooling , totally eliminating the overheating on delayed take off or prolonged climbs. It has also added 4 kts to top speed and improved fuel consumption. As you can see from the attached mathematical analysis a 12 degree twist is optimised for air flow through the prop of about 40 kts, which is what you get sitting on the ground at about 1/2 throttle, before take off. At 100kts + you have negative AoAs in the central portion of the propeller, which doesn't help anything. It's no coincidence that all really fast planes (Spitfires, Red Bull racing planes, turboprops, etc) have props with twist more than 20 degrees. Regards, David Joyce, G-XSDJ ----- Original Message ----- From: "Fred Klein" Sent: Saturday, March 21, 2009 1:12 AM Subject: Re: Europa-List: Constant Speed Props, etc. > > > On Mar 20, 2009, at 2:00 PM, Paul McAllister wrote: > >> I am not an aerodynamicst, not even an amature one but I was wondering >> why you didn't think the Kiev blades will be much of an improvement >> over the Warp Drive blades. > > Bud, > > I too was surprised at your apparent skepticism as to whether those Kiev > blades may offer improvement over the current WD blades in the Airmaster > hub. > > I had several long emails w/ Martin on the subject...perhaps 2 years > ago...and my recollection is that he was quite candid about the WD blades > being less than optimal given the flight envelope and length limitations > of the blades for the Europa. My understanding is that the WD blade > stock is much longer, and when cut down to length required, they lose > much of their twist...to such an extent I've read that the inner portions > of the blades create negative thrust under certain conditions. I've > speculated that the relative lack of twist may be a factor in engine > cooling...just speculation, I have, of course, no direct experience. > > Assuming that the "432" references a new hub, I hope it's available with > other than a Rotax flange. > > Fred > > > ________________________________ Message 3 _____________________________________ Time: 05:55:41 AM PST US From: Robert Borger Subject: Re: Europa-List: Constant Speed Props, etc. Bud, Thanks very much for the excellent and concise description of the problem. Bob Borger Europa Kit #A221 N914XL, XS Mono, Intercooled 914, Airmaster C/S http://www.europaowners.org/N914XL Aircraft Flying! 3705 Lynchburg Dr. Corinth, TX 76208 Home: 940-497-2123 Cel: 817-992-1117 On Mar 21, 2009, at 0:22, ALAN YERLY wrote: > Paul, > I am only a junior aerodynamicist. Propeller blade design is still > a zen art. Too many theta, beta sigma deltas to patiently wade > through and design a prop. The math is not beyond me, ( I have a > computer program for doing the gymnastics and iterations, (but my > kid the aero engineer has to get me in to it...go figure). I can > say that most designs take into account the assumptions of where the > max efficiency of their design will be optimized. When designing a > prop blade, it is hard to get a prop that does all things well. We > buy a CS prop to accelerate fast, give max climb and optimum > efficiency at the exact torque/power curve for the specified > aircraft at a specified cruise speed and altitude, but propeller > blade designers don't know your plane, engine or the altitudes you > intend to use, so they assume for a specific engine and speed/ > altitude, and don't tell anyone. For you Paul, the next two > paragraphs are a bit basic, but somebody less experienced may glean > some knowledge or correct me. > > Example: For max static thrust and quick acceleration of say a > float plane/airboat, you design the prop so the entire prop blade is > pulling very close to the stall angle based on the rotational speed > for takeoff power/torque and forward speed. This gets the plane on > the step quickly and off the water. But, once you pass about 80 Kts > the blade angle of attack falls off due to forward speed, cowl > stagnation point / flow interruption and the reduction of power to > max continuous for the climb. To design a perfectly optimized fixed > pitch propeller, the following is optimized by trial and error: For > takeoff, the blade bites as described above. During the transition > to climb, the tip unloads slightly and the root takes up the > difference. At cruise the tip unloads further leaving the root to > take up the slack. Balancing this twist means the propeller > designer and aircraft/power plant designer must cooperate to achieve > this goal. So the fixed pitch designer at WD makes his blade so > that there is extra pitch at the hub decreasing to the tip so as > speed increases the root pulls the load the tip can't, but only to a > point. Typically 7500-9500 feet and 120 Kts is about max you'll > ever get unless you've got a clean airplane like a Europa and you > get 130 Kts... > > Take the Airmaster with the Warp Drive (WD) blades. On a slow > aircraft like a Rans S-7 or a Kitfox. Let's say their optimum > cruise will be 110 Kts at 7500 feet for that plane. A fixed 68 inch > WD prop can be twisted to give max static thrust, and high climb, > but then the pitch is too low for optimum cruise, and the plane only > makes 105 Kts because the tip is unloaded and prop efficiency > drops. So we put the WD blades on a CS prop hub. Now the static > thrust and high climb are there but once at cruise we adjust the > pitch to coarse to allow the prop to bite more and be at the optimum > pitch for 110-115 Kts or a little higher. > > Now let's go to our 914 and 15,000 foot cruise. The WD blade is a > good strong blade, but the assumed efficient cruise altitude of the > blade may not have been optimized for 15,000 feet and 175 KTAS > pulled by an engine making 70 HP and 70 ft lbs of torque at > altitude. As altitude goes up, we know the rules about how density > affects the TAS. The blade (wing) of the prop is now at a higher > Reynolds number which results in a lower lift curve slope. In the > rarified air up there, the dynamic pressure is less so less lift (or > pull) is provided, and the velocity (True) is higher, so the vector > made by the rotational angle of the disk and the Velocity vector > forces the blade to a higher angle of attack to bite (course prop > pitch). The higher altitude decreases the thrust (or lift of the > blade) and you find yourself with the blade generating max lift, and > or in fact stalling at some point and not operating efficiently. I > believe it is a high probability the torque of the 914 engine is > higher than the prop requires for max efficiency at altitude. Hence > the CS mechanism adjusts the prop to a more coarse setting to absorb > the torque demanded by the throttle, but that puts the blade at an > angle which lowers the overall efficiency of the blade. Therefore > you experience the effect of no appreciable increase in speed the > higher you go. The WD blade is most probably being over driven by > the 914 at altitude. I presume you experimented with many manual > pitch settings, manifold pressures and RPM settings looking for max > performance. I am well behind you as my schedule does not allow a > lot of time to climb to altitude and test, but I am hoping for a > break this spring. My gut feeling will be that I will need to > throttle back to gain efficiency and be satisfied with 40 mpg > instead of 30 and get to my destination a little slower. > > From my Airplane Aerodynamics reference by Dommasch, Sherry and > Connolly, "Because of the factors discussed above, we find that the > over all shape of a propeller is determined by the maximum speed at > which it must operate efficiently. A low-speed planform should be > slender with well rounded tips, whereas a high speed planform should > have a large chord, with the maximum amount of blade area > concentrated in the minimum diameter. Because the major portion of > the thrust is derived from the outer portion of the blades, a high > speed propeller is generally characterized by paddle shaped tips > that place the area where it can best be utilized. > > What's the fix? To translate the above academic explanation, the > best example is to look at WWII prop designs of the VDM propeller > used on the ME 109. Early versions had the thin profile blade we > see on our WD narrow chord blades. But as engine performance and > the demand for higher altitudes increased, the designers went to a > wider prop of more surface area to absorb the torque, and to create > more thrust out of the blade normally lost due to the effects of > higher altitude. They were limited by the diameter of the prop due > to ground clearance, and production forced them to stick to three > blades so they fattened the blades, increased the pitch of the root > and went to war (see pictures of the Ta 152 for an even higher > altitude and speed prop). Takeoff performance wasn't that much > better because the larger blade area demanded more torque/power than > available and the pitch was reduced lowering efficiency at takeoff, > but mid altitude climb and acceleration, as well as cruise was > improved. By the way the VDM was a variable pitch prop, with a > visual indicator of prop pitch in the cockpit, not a constant speed > prop. Talk about pilot work load. In the US we did the same for > the P-47 by changing the Hamilton Standard prop from a thin blade to > a thicker blade as WD did and made the prop Constant Speed to reduce > pilot work load. God I love history... > > Right now Airmaster is looking at a number of blades that fit our > hub and future hubs. Problem is, the blade designs are many, and > twist features are not that much different than the WD. My comment > on the Kiev blade is that it doesn't appear to have much more twist, > but it does seem to have more area. It is in use on lower altitude/ > low performance ultralight and trike aircraft. It is light, but, is > its hollow design tough enough for the 914 at high Q, and for our > Europa, all the Kiev prop blades are longer (67") than we can > normally use. Sensenich (fixed) and Whirlwind (oil pump driven > hydraulic) have wider chord blades than the WD and may hold an > advantage in some areas, but give a thumping sound as the pressure > wave hits the aircraft. Airmaster does use their own Europa to test > prop blade performance. In my opinion, if some blade was > significantly better for the three blade AP332, it would be on there > already. Since we have new meat in the prop market, there are more > choices in the blades, and the Rotax / WD is very popular so the new > blades favor that LSA speed/altitude market now and use a similar > hub attachment and blade design. I'm afraid there is not a lot of > call for high altitude low power high speed props like we need for > cruise at 15,000 feet. Also the market has to be satisfied, many > lower performance aircraft enjoy the Airmaster and aren't in need of > a major change, while other markets need a longer two blade prop for > static thrust. Wider blades restrict feathering or cowl clearance > in some aircraft. These are the things being evaluated at this > time. It takes time, money and testing. > > Good Night, > > Bud ________________________________ Message 4 _____________________________________ Time: 11:22:34 AM PST US From: Fred Klein Subject: Europa-List: Constant Speed Props, etc. For anyone who hasn't OD'ed on this topic, here's a link to what I thought was a fascinating article by Paul Lipps and the props he's fitted to his O-235 powered Lancair, a ship which shares the Europa's niche, i.e., light weight, low powered, high speed cruise, at high(er) altitudes. http://www.eaa.org/experimenter/articles/2009-02_elippse.asp ________________________________ Message 5 _____________________________________ Time: 12:09:44 PM PST US From: glenn crowder Subject: Europa-List: Catto ground adjustable prop for LSA market One of the Zenair pilots at my field has been in contact with Craig Catto a t Cattoprops.com. Craig confirms he is testing a ground adjustable prop for the LSA market (think Rotax) and is te sting it against the Kiev prop. He says it is significantly better than the Kiev so this is great news. Catto make s racing props so knows a thing or two about prop twist. I have 45 deg twist on my fixed pitch 64x62 three blade Catto. Craig is very hard to get ahold of and is usually easier to get on the phone rather than emails. Glenn > From: fklein@orcasonline.com > To: europa-list@matronics.com > Subject: Re: Europa-List: Constant Speed Props=2C etc. > Date: Fri=2C 20 Mar 2009 18:12:56 -0700 > > > > On Mar 20=2C 2009=2C at 2:00 PM=2C Paul McAllister wrote: > > > I am not an aerodynamicst=2C not even an amature one but I was > > wondering why you didn't think the Kiev blades will be much of an > > improvement over the Warp Drive blades. > > Bud=2C > > I too was surprised at your apparent skepticism as to whether those > Kiev blades may offer improvement over the current WD blades in the > Airmaster hub. > > I had several long emails w/ Martin on the subject...perhaps 2 years > ago...and my recollection is that he was quite candid about the WD > blades being less than optimal given the flight envelope and length > limitations of the blades for the Europa. My understanding is that > the WD blade stock is much longer=2C and when cut down to length > required=2C they lose much of their twist...to such an extent I've read > that the inner portions of the blades create negative thrust under > certain conditions. I've speculated that the relative lack of twist > may be a factor in engine cooling...just speculation=2C I have=2C of > course=2C no direct experience. > > Assuming that the "432" references a new hub=2C I hope it's available > with other than a Rotax flange. > > Fred > > =========== =========== =========== =========== > > > _________________________________________________________________ Hotmail=AE is up to 70% faster. Now good news travels really fast. http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_HM_70faster_03200 9 ________________________________ Message 6 _____________________________________ Time: 06:14:20 PM PST US From: John & Paddy Wigney Subject: Europa-List: Re: Constant Speed Props, etc. Dear Europaphiles, I have been watching the recent thread on Woodcomp props with much interest and I thought that some observations I have mentioned before on the Whirl Wind hydraulic constant speed prop may be of interest, see http://www.whirlwindaviation.com/series100.php. This prop may not be inexpensive but it is good. I have flown 600 + hours with mine from new and have found it to be completely trouble free and it gives excellent performance. It is also one of the lightest props available with a weight of 9.3 lbs. I bought it after listening to Kim Prout at Oshkosh many years ago. Paraphrasing, he said that it was the most significant single contribution to the performance of his Europa. I believe that the Series 100 Whirl Wind prop was designed specifically for the Europa and for details of the performance of Kim's plane, you can see the CAFE report at http://cafefoundation.org/v2/pdf_apr/Europa%20APR.pdf . As you will see, Kim's Europa Classic with the 80 HP 912 is no slouch. On my plane for take-off, I set the vernier control to max which gives 5,800 rpm and after take-off, one can easily wind back to 5,500 rpm while remaining at full throttle. I normally cruise at settings between 5,100 and 5,500 rpm. If one chooses, the governor will control any speed from about 3,800 up to 5,800 rpm. Whirl Wind has been producing propellers for Unlimited category aerobatic competitors as well as for airshow performers for many years so the basic design is very well proven. To install this prop on a 912/ 912S/914, you must have the gearbox modification which allows the governor to supply control pressure oil to the hollow prop drive shaft. It is preferable to specify this before you take delivery of the engine. The Czech made Jihostroj governor which is supplied as part of the package has proved to be completely reliable and is very accurate. The governor mounts on the engine auxiliary pad which is normally used for a vacuum pump, so one has to rely on non-vacuum instruments. I am not familiar with the internals of the Whirlwind hub but there is one large central adjustment nut which sets the fine pitch stop to give a corresponding max speed of 5,800 rpm at full throttle at take off. I have no business relationship with Whirl Wind. Please contact if you have any questions. Cheers, John N262WF, mono XS, 912S Mooresville, North Carolina 704-664-4167 ________________________________ Message 7 _____________________________________ Time: 07:06:07 PM PST US From: "ALAN YERLY" Subject: Re: Europa-List: Catto ground adjustable prop for LSA market Glenn, My experience with Catto is from one O-200 Europa and a couple of RV's. Phil Catto makes beautiful props. His fixed pitch props are better than some constant speed props. He gets it right. Bud ----- Original Message ----- From: glenn crowder To: europa-list@matronics.com Sent: Saturday, March 21, 2009 3:00 PM Subject: Europa-List: Catto ground adjustable prop for LSA market One of the Zenair pilots at my field has been in contact with Craig Catto at Cattoprops.com. Craig confirms he is testing a ground adjustable prop for the LSA market (think Rotax) and is testing it against the Kiev prop. He says it is significantly better than the Kiev so this is great news. Catto makes racing props so knows a thing or two about prop twist. I have 45 deg twist on my fixed pitch 64x62 three blade Catto. Craig is very hard to get ahold of and is usually easier to get on the phone rather than emails. Glenn > From: fklein@orcasonline.com > To: europa-list@matronics.com > Subject: Re: Europa-List: Constant Speed Props, etc. > Date: Fri, 20 Mar 2009 18:12:56 -0700 > > > > On Mar 20, 2009, at 2:00 PM, Paul McAllister wrote: > > > I am not an aerodynamicst, not even an amature one but I was > > wondering why you didn't think the Kiev blades will be much of an > > improvement over the Warp Drive blades. > > Bud, > > I too was surprised at your apparent skepticism as to whether those > Kiev blades may offer improvement over the current WD blades in the > Airmaster hub. > > I had several long emails w/ Martin on the subject...perhaps 2 years > ago...and my recollection is that he was quite candid about the WD > blades being less than optimal given the flight envelope and length > limitations of the blades for the Europa. My understanding is that > the WD blade stock is much longer, and when cut down to length > required, they lose much of their twist...to such an extent I've read > that the inner portions of the blades create negative thrust under > certain conditions. I've speculated that the relative lack of twist > may be a factor in engine cooling...just speculation, I have, of > course, no direct experience. > > Assuming that the "432" references a new hub, I hope it's available > with other than a ===================== >===== > > > ------------------------------------------------------------------------- ----- Hotmail=AE is up to 70% faster. Now good news travels really fast. Find out more. http://www.matronics.com/Navigator?Europa-List http://www.matronics.com/contribution ________________________________ Message 8 _____________________________________ Time: 09:58:13 PM PST US From: glenn crowder Subject: Europa-List: Bolly Prop Australia to release high twist blade for LSA market Bolly Prop Australia is releasing their Series 5 blade for faster aircraft. Their older blades are compatible with Warp Drive Hubs. Not sure about the Series 5 but most likely will be WD compatible. http://www.bollyaviation.com.au/Propellers/Series5/tabid/100/language/en-AU /Default.aspx Glenn Crowder _________________________________________________________________ Internet Explorer 8 ' Now Available. Faster=2C safer=2C easier. ________________________________ Message 9 _____________________________________ Time: 10:55:17 PM PST US From: "craig bastin" Subject: RE: Europa-List: Bolly Prop Australia to release high twist blade for LSA market I have been talking to another australian company that make a VP hub to suit the BOLLY blades and he indicated to me that the bolly blades require the bolly hub or their VP hub. I may be wrong but that is what was indicated to me. Bolly are also soon to release a VP hub of thier own. Given the article on the elippse props and the performance achieved with smaller props and more blades vs larger 2 blade props (220mph on the 64" two blade vs 250mph for the 59" 4 blade) I think that the 4 blade prop could be worth a look. -----Original Message----- From: owner-europa-list-server@matronics.com [mailto:owner-europa-list-server@matronics.com]On Behalf Of glenn crowder Sent: Sunday, 22 March 2009 2:56 PM To: europa-list@matronics.com Subject: Europa-List: Bolly Prop Australia to release high twist blade for LSA market Bolly Prop Australia is releasing their Series 5 blade for faster aircraft. Their older blades are compatible with Warp Drive Hubs. Not sure about the Series 5 but most likely will be WD compatible. http://www.bollyaviation.com.au/Propellers/Series5/tabid/100/language/en-AU/ Default.aspx Glenn Crowder ---------------------------------------------------------------------------- -- Internet Explorer 8 Now Available. 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