---------------------------------------------------------- TeamGrumman-List Digest Archive --- Total Messages Posted Wed 06/29/11: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:02 AM - Re: Prop pitch (Bruce Smith) 2. 05:26 AM - Re: Prop pitch (Michael W. Meyer) 3. 11:44 AM - Re: Prop pitch (Gary Vogt) 4. 11:59 AM - Re: Prop pitch (Gary Vogt) ________________________________ Message 1 _____________________________________ Time: 04:02:18 AM PST US From: Bruce Smith Subject: Re: TeamGrumman-List: Prop pitch Gary, No personal experience with this. It was a topic that came up over a fly-out dinner to Reading PA the other day. It seems that with all the load components (centrifugal and lift), the blades might change. Bruce On Jun 28, 2011, at 10:46 PM, Gary Vogt wrote: > Bruce, > > That's a very good question. My opinion is that there is enough elasticity in the blade that it should not change pitch over time. That is just a guess. > > Why? Do you have a prop with mixed pitches? > > Gary > > From: Bruce Smith > To: teamgrumman-list@matronics.com > Sent: Tue, June 28, 2011 6:52:23 PM > Subject: TeamGrumman-List: Prop pitch > > > > > ________________________________ Message 2 _____________________________________ Time: 05:26:02 AM PST US From: "Michael W. Meyer" Subject: Re: TeamGrumman-List: Prop pitch Navy steam turbines exhibit something called blade creep - they will get lon ger over life due to the centrifugal force and thermal cycles they experienc e. However, those turbines are in continuous operation for long periods of t ime, we're talking about the fine tolerances of turbine assemblies, and it s till takes a ship's lifetime to show up. The metallurgy's very different bet ween steam turbine blades and our propeller blades, but I still kinda doubt i t happens to a noticeable degree given the lack of a high temperature enviro nment and relatively low duty cycle of our props. Thanks, Michael Michael W Meyer michael@flightsked.com m: +1 781.248.7550 (sent from my iPhone, please excuse the brevity) On Jun 29, 2011, at 3:59, Bruce Smith wrote: > Gary, > > No personal experience with this. It was a topic that came up over a fly-o ut dinner to Reading PA the other day. It seems that with all the load compo nents (centrifugal and lift), the blades might change. > > Bruce > > On Jun 28, 2011, at 10:46 PM, Gary Vogt wrote: > >> Bruce, >> >> That's a very good question. My opinion is that there is enough elastici ty in the blade that it should not change pitch over time. That is just a g uess. >> >> Why? Do you have a prop with mixed pitches? >> >> Gary >> >> From: Bruce Smith >> To: teamgrumman-list@matronics.com >> Sent: Tue, June 28, 2011 6:52:23 PM >> Subject: TeamGrumman-List: Prop pitch >> >> >> >> href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.m atronics.com/Navigator?TeamGrumman-List >> href="http://forums.matronics.com">http://forums.matronics.com >> href="http://www.matronics.com/contribution">http://www.matronics.com/c ontribution >> >> > ________________________________ Message 3 _____________________________________ Time: 11:44:58 AM PST US From: Gary Vogt Subject: Re: TeamGrumman-List: Prop pitch Bruce, I know they change in flight. I've seen high speed video of a prop in flight. Trust me, something you don't want to see. What I am not sure of is whether the prop takes a new set after repeated loadings. I'm calling my prop guy now. . . . . . . . . Mike says that the metal will relax some and flatten out the pitch over time but it is usually only a very small amount. Mike has been doing props for 30 years. Gary ________________________________ From: Bruce Smith Sent: Wed, June 29, 2011 3:59:12 AM Subject: Re: TeamGrumman-List: Prop pitch Gary, No personal experience with this. It was a topic that came up over a fly-out dinner to Reading PA the other day. It seems that with all the load components (centrifugal and lift), the blades might change. Bruce On Jun 28, 2011, at 10:46 PM, Gary Vogt wrote: Bruce, > > >That's a very good question. My opinion is that there is enough elasticity in >the blade that it should not change pitch over time. That is just a guess. > > >Why? Do you have a prop with mixed pitches? > > >Gary > > ________________________________ From: Bruce Smith >To: teamgrumman-list@matronics.com >Sent: Tue, June 28, 2011 6:52:23 PM >Subject: TeamGrumman-List: Prop pitch > > > >href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List > href="http://forums.matronics.com">http://forums.matronics.com >href="http://www.matronics.com/contribution">http://www.matronics.com/contribution > > > ________________________________ Message 4 _____________________________________ Time: 11:59:15 AM PST US From: Gary Vogt Subject: Re: TeamGrumman-List: Prop pitch Hi Mike, Long time no see. Talking about turbine blades . . . . while going to school at the Von Karman Institute for Fluid Dynamics in Belgium, we did flow visualization using fine dust particles, smoke, and lasers. We watched the flow separation and turbulence at the blade tips on a jet engine turning 10 to 10,000 rpms. It was pretty cool. I don't recall the gap to the wall but I know it was close. So, Mike, How are things? Stop by some time and bring the Mrs. Gary ________________________________ From: Michael W. Meyer Sent: Wed, June 29, 2011 5:23:16 AM Subject: Re: TeamGrumman-List: Prop pitch Navy steam turbines exhibit something called blade creep - they will get longer over life due to the centrifugal force and thermal cycles they experience. However, those turbines are in continuous operation for long periods of time, we're talking about the fine tolerances of turbine assemblies, and it still takes a ship's lifetime to show up. The metallurgy's very different between steam turbine blades and our propeller blades, but I still kinda doubt it happens to a noticeable degree given the lack of a high temperature environment and relatively low duty cycle of our props. Thanks, Michael Michael W Meyer michael@flightsked.com m: +1 781.248.7550 (sent from my iPhone, please excuse the brevity) On Jun 29, 2011, at 3:59, Bruce Smith wrote: Gary, > > >No personal experience with this. It was a topic that came up over a fly-out >dinner to Reading PA the other day. It seems that with all the load components >(centrifugal and lift), the blades might change. > > >Bruce > > >On Jun 28, 2011, at 10:46 PM, Gary Vogt wrote: > >Bruce, >> >> >>That's a very good question. My opinion is that there is enough elasticity in >>the blade that it should not change pitch over time. That is just a guess. >> >> >>Why? Do you have a prop with mixed pitches? >> >> >>Gary >> >> >> ________________________________ From: Bruce Smith >>To: teamgrumman-list@matronics.com >>Sent: Tue, June 28, 2011 6:52:23 PM >>Subject: TeamGrumman-List: Prop pitch >> >> >> >>href="http://www.matronics.com/Navigator?TeamGrumman-List">http://www.matronics.com/Navigator?TeamGrumman-List >> href="http://forums.matronics.com">http://forums.matronics.com >>href="http://www.matronics.com/contribution">http://www.matronics.com/contribution >> >> >> > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message teamgrumman-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/TeamGrumman-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/teamgrumman-list Browse Digests http://www.matronics.com/digest/teamgrumman-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.