---------------------------------------------------------- KIS-List Digest Archive --- Total Messages Posted Fri 02/18/11: 8 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 11:56 AM - Re: 2010 Holiday trip (BlueSkyFlier) 2. 12:23 PM - Re: CATTO 3 bladed prop (BlueSkyFlier) 3. 12:40 PM - Re: Maneuvering Speed SAIB (BlueSkyFlier) 4. 03:36 PM - Re: Re: CATTO 3 bladed prop (Scott Stearns) 5. 04:10 PM - Re: Re: CATTO 3 bladed prop (Scott Stearns) 6. 04:41 PM - Re: Re: CATTO 3 bladed prop (Galin Hernandez) 7. 05:42 PM - Re: Re: CATTO 3 bladed prop (Robert Reed) 8. 08:12 PM - Re: Re: Maneuvering Speed SAIB (Flyinisfun@aol.com) ________________________________ Message 1 _____________________________________ Time: 11:56:38 AM PST US Subject: KIS-List: Re: 2010 Holiday trip From: "BlueSkyFlier" Hi John (Petrie) A belted answer to your question regarding the Henshaw challenge ... I know all about it and followed the last two attempts closely. Not my idea of enjoyable (or safe) flying - as the latest attempt illustrated. I believe the Glassair is still sitting in Windhoek (which happens to be my home town :o)) My KIS has only 130hp at ground level, so not much of a chance to compete for the record anyway. I'll just make my way down to Cape Town at my leisure. If I add extra fuel tanks I can do 1000nm at a stretch. That will make for five stops for the plane - maybe more for me :o). Not yet made up my mind as to whether adding the extra tanks is worth the trouble. Depends on how easy or difficult I find it to find Avgas when arranging with FBOs for stopovers. Have you decided on what your next plane will be after selling the KIS? Regards, Alfred -------- _________________________________________ Read this topic online here: http://forums.matronics.com/viewtopic.php?p=331442#331442 ________________________________ Message 2 _____________________________________ Time: 12:23:05 PM PST US Subject: KIS-List: Re: CATTO 3 bladed prop From: "BlueSkyFlier" Hi Galin, As part of making a decision about my new propeller (and also because I wanted to do it) I created an performance model for the KIS which integrates propleller and airframe models. To my surprise and contrary to popular wisdom the results showed that (a) larger diameter is not necessarily always better and (b) 3 bladed props are rarely (if ever) better than 2 bladed props At normal operating RPMs the parasitic drag of the third blade easily negates the reduction in induced drag due to lower power loading per blade. So I would suggest staying with a two blade prop unless ground clearance issues makes 3 blades an unavoidable necessity. For any particular density altitude and RPM, there is an optimum prop diameter which maximises residual engine power across the speed range. The diameter determines the prop blade power loading which in turn determines the prop drag losses. Therefore, optimising diameter is equivalent to optimising prop drag losses across the speed range for chosen RPM and altitude. These non-linear characteristics of the propulsion system only become apparent when the airframe and propeller are integrated together. Regards, Alfred -------- _________________________________________ Read this topic online here: http://forums.matronics.com/viewtopic.php?p=331443#331443 ________________________________ Message 3 _____________________________________ Time: 12:40:53 PM PST US Subject: KIS-List: Re: Maneuvering Speed SAIB From: "BlueSkyFlier" Agreed Sott. All moment arms come into play - that's why weight distribution (weight as a force) is so important. With the big 360 up front you know about that. Bottom line - slow down when the air gets turbulent, and then slow down even more if airframe weight distribution is not as good as it could be. Regards, Alfred -------- _________________________________________ Read this topic online here: http://forums.matronics.com/viewtopic.php?p=331444#331444 ________________________________ Message 4 _____________________________________ Time: 03:36:07 PM PST US From: Scott Stearns Subject: Re: KIS-List: Re: CATTO 3 bladed prop I remember when the 'new' cessna 182 came out.- The 3 bladed propeller wa s an option.- The POH showed no difference in performance between the two and three bladed propellers, except the 3 bladed propeller was 40 pounds h eavier and a $10,000+ option.- I've never seen a new 182 with a two blade d propeller and a lot of older 182 have converted to three bladed props.- It does look cool.... - Scott --- On Fri, 2/18/11, BlueSkyFlier wrote: From: BlueSkyFlier Subject: KIS-List: Re: CATTO 3 bladed prop Hi Galin, As part of making a decision about my new propeller (and also because I wan ted to do it) I created an performance model for the KIS which integrates p ropleller and airframe models. To my surprise and contrary to popular wisdom the results showed that (a) larger diameter is not necessarily always better and (b) 3 bladed props are rarely (if ever) better than 2 bladed props At normal operating RPMs the parasitic drag of the third blade easily negat es the reduction in induced drag due to lower power loading per blade. So I would suggest staying with a two blade prop unless ground clearance issues makes 3 blades an unavoidable necessity. For any particular density altitude and RPM, there is an optimum prop diame ter which maximises residual engine power across the speed range. The diameter determines the prop blade power loading which in turn determin es the prop drag losses. Therefore, optimising diameter is equivalent to op timising prop drag losses across the speed range for chosen RPM and altitud e. These non-linear characteristics of the propulsion system only become appar ent when the airframe and propeller are integrated together. Regards, - - - - - - Alfred -------- _________________________________________ Read this topic online here: http://forums.matronics.com/viewtopic.php?p=331443#331443 le, List Admin. =0A=0A=0A ________________________________ Message 5 _____________________________________ Time: 04:10:18 PM PST US From: Scott Stearns Subject: Re: KIS-List: Re: CATTO 3 bladed prop Also,-a one bladed propeller is really best, just a bit hard to do.- So me model racing airplanes use one bladed propellers with a counter weight t o balance the prop. - Scott --- On Fri, 2/18/11, BlueSkyFlier wrote: From: BlueSkyFlier Subject: KIS-List: Re: CATTO 3 bladed prop Hi Galin, As part of making a decision about my new propeller (and also because I wan ted to do it) I created an performance model for the KIS which integrates p ropleller and airframe models. To my surprise and contrary to popular wisdom the results showed that (a) larger diameter is not necessarily always better and (b) 3 bladed props are rarely (if ever) better than 2 bladed props At normal operating RPMs the parasitic drag of the third blade easily negat es the reduction in induced drag due to lower power loading per blade. So I would suggest staying with a two blade prop unless ground clearance issues makes 3 blades an unavoidable necessity. For any particular density altitude and RPM, there is an optimum prop diame ter which maximises residual engine power across the speed range. The diameter determines the prop blade power loading which in turn determin es the prop drag losses. Therefore, optimising diameter is equivalent to op timising prop drag losses across the speed range for chosen RPM and altitud e. These non-linear characteristics of the propulsion system only become appar ent when the airframe and propeller are integrated together. Regards, - - - - - - Alfred -------- _________________________________________ Read this topic online here: http://forums.matronics.com/viewtopic.php?p=331443#331443 le, List Admin. =0A=0A=0A ________________________________ Message 6 _____________________________________ Time: 04:41:13 PM PST US From: Galin Hernandez Subject: Re: KIS-List: Re: CATTO 3 bladed prop Yes, I am aware of what you pointed out about the different props. But, I want to use a smaller diameter prop since I fly in and out of runways that are not very well kept. I have a constant struggle with nicks on my 76" prop. I installed prop guard on the leading edge. It lessened the problem, but it still exists more than I like. That is why I wanted a PIREP if anybody had a CATTO prop and how it performed. Galin On Fri, Feb 18, 2011 at 2:21 PM, BlueSkyFlier wrote: > > > > Hi Galin, > > As part of making a decision about my new propeller (and also because I > wanted to do it) I created an performance model for the KIS which integrates > propleller and airframe models. > > To my surprise and contrary to popular wisdom the results showed that > (a) larger diameter is not necessarily always better and > (b) 3 bladed props are rarely (if ever) better than 2 bladed props > > At normal operating RPMs the parasitic drag of the third blade easily > negates the reduction in induced drag due to lower power loading per blade. > So I would suggest staying with a two blade prop unless ground clearance > issues makes 3 blades an unavoidable necessity. > > For any particular density altitude and RPM, there is an optimum prop > diameter which maximises residual engine power across the speed range. > The diameter determines the prop blade power loading which in turn > determines the prop drag losses. Therefore, optimising diameter is > equivalent to optimising prop drag losses across the speed range for chosen > RPM and altitude. > > These non-linear characteristics of the propulsion system only become > apparent when the airframe and propeller are integrated together. > > Regards, > Alfred > > -------- > _________________________________________ > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=331443#331443 > > ________________________________ Message 7 _____________________________________ Time: 05:42:33 PM PST US From: Robert Reed Subject: Re: KIS-List: Re: CATTO 3 bladed prop Well, there is one thing you won't have to worry about with the Catto 3 blad ed is any significant weight increase. It is a very light prop. I know all the issues of 2 vs. 3 but my main reason for the Catto 3 blade was the quie t operation of the 3 bladed prop. My wife has migranes and I have made seve ral changes to reduce cabin noise. Besides, it's one of the sexiest looking props around. Bob Sent from my iPhone On Feb 18, 2011, at 5:25 PM, Scott Stearns wrote: > I remember when the 'new' cessna 182 came out. The 3 bladed propeller was an option. The POH showed no difference in performance between the two and three bladed propellers, except the 3 bladed propeller was 40 pounds heavie r and a $10,000+ option. I've never seen a new 182 with a two bladed propel ler and a lot of older 182 have converted to three bladed props. It does lo ok cool.... > > Scott > > --- On Fri, 2/18/11, BlueSkyFlier wrote: > > From: BlueSkyFlier > Subject: KIS-List: Re: CATTO 3 bladed prop > To: kis-list@matronics.com > Date: Friday, February 18, 2011, 12:21 PM > > > > Hi Galin, > > As part of making a decision about my new propeller (and also because I wa nted to do it) I created an performance model for the KIS which integrates p ropleller and airframe models. > > To my surprise and contrary to popular wisdom the results showed that > (a) larger diameter is not necessarily always better and > (b) 3 bladed props are rarely (if ever) better than 2 bladed props > > At normal operating RPMs the parasitic drag of the third blade easily nega tes the reduction in induced drag due to lower power loading per blade. So I would suggest staying with a two blade prop unless ground clearance issues m akes 3 blades an unavoidable necessity. > > For any particular density altitude and RPM, there is an optimum prop diam eter which maximises residual engine power across the speed range. > The diameter determines the prop blade power loading which in turn determi nes the prop drag losses. Therefore, optimising diameter is equivalent to op timising prop drag losses across the speed range for chosen RPM and altitude . > > These non-linear characteristics of the propulsion system only become appa rent when the airframe and propeller are integrated together. > > Regards, > Alfred > > -------- > _________________________________________ > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=331443#331443 > > > http://www.matronics.com/Nav - MATRONICS WEB &nbsf="http://www.matronics.com/contribution" target=_blank>http:// www.matr==================== > > > > > > ========================== ========= ========================== ========= ========================== ========= ========================== ========= > ________________________________ Message 8 _____________________________________ Time: 08:12:00 PM PST US From: Flyinisfun@aol.com Subject: Re: KIS-List: Re: Maneuvering Speed SAIB Man do I ever know about maneuvering speed. I have the 0-320 Lyc. in my two place and those little short wings just don't ride the bumps very well. I have hit rough air and cracked my head on the ceiling several times before I could get it slowed down. I have tested my wings several times trying to run my engine wide open and couldn't shut it down fast enough. I can indicate 180 mph full throttle and I believe that is about the limit I want to see. Is anybody else consisently doing more? Jesse Agreed Sott. All moment arms come into play - that's why weight distribution (weight as a force) is so important. With the big 360 up front you know about that. Bottom line - slow down when the air gets turbulent, and then slow down even more if airframe weight distribution is not as good as it could be. 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