---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Sat 04/11/09: 10 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:56 AM - Re: XC Photo (icrashrc) 2. 04:47 AM - Re: harmonics (Thom Riddle) 3. 05:21 AM - Re: Re: XC Photo (John Hauck) 4. 05:50 AM - Re: harmonics (JetPilot) 5. 08:24 AM - Re: V.W.conversion (Rick Lewis) 6. 08:42 AM - Re: Stits (DAquaNut@aol.com) 7. 08:58 AM - Re: Re: harmonics (Herb) 8. 09:31 AM - Re: Re: V.W.conversion (frank.goodnight) 9. 01:42 PM - Re: Re: V.W.conversion (Richard & Martha Neilsen) 10. 06:41 PM - Re: Re: harmonics (Jack B. Hart) ________________________________ Message 1 _____________________________________ Time: 03:56:40 AM PST US Subject: Kolb-List: Re: XC Photo From: "icrashrc" John, That is a great picture! Any chance you could send me the full size version of this pic via email? Thanks, John Hauck wrote: > Bumped into this old photo while looking for something else. > > I believe this was taken on Bonneville Salt Flats, Utah, May 2007. > > The black line used for speed runs on the flats, is visible in the photo, > running right below John W's Kolbra. > > john h > mkIII -------- Scott www.ill-EagleAviation.com do not archive Read this topic online here: http://forums.matronics.com/viewtopic.php?p=238688#238688 ________________________________ Message 2 _____________________________________ Time: 04:47:00 AM PST US Subject: Kolb-List: Re: harmonics From: "Thom Riddle" If the harmonic is coming from some airframe part and is a result of engine/prop vibrations, then the engine/prop vibrations being transmitted to this airframe part would be lessened if the mounts were a little softer. In any case a change in mount stiffness would change the natural harmonic frequency which might make the current troubling sound go away, go to a different pitch, go to a different part of the airframe or get worse. Difficult to predict. Assuming the prop is statically balanced, blades pitched equally, and tracked properly, the next step I would consider is dynamic engine/prop balancing. Doing so may solve your problem at the source, which would be the best solution. Many class D and bigger airports with reasonably complete maintenance shops have the capability to do dynamic engine/prop balancing. Last time I checked local prices it was about $250. -------- Thom Riddle Buffalo, NY http://riddletr.googlepages.com/sportpilot-cfi http://riddletr.googlepages.com/a%26pmechanix A complex system that works is invariably found to have evolved from a simple system that works. - John Gaule Read this topic online here: http://forums.matronics.com/viewtopic.php?p=238690#238690 ________________________________ Message 3 _____________________________________ Time: 05:21:16 AM PST US From: "John Hauck" Subject: Re: Kolb-List: Re: XC Photo > That is a great picture! Any chance you could send me the full size version of this pic via email? > Thanks, Scott: If I can find my original file, it will be on the way. If John W took this photo, then we are out of luck. john h mkIII ________________________________ Message 4 _____________________________________ Time: 05:50:48 AM PST US Subject: Kolb-List: Re: harmonics From: "JetPilot" You mentioned that John H. mentioned the gear box spacers, this makes several different people that I have heard mention this. The others were not on the Kolb list, but it seems to be something important with the 912. I am not sure what the symptom is if the spacing is out of tolerance, but I will ask. The SS seems like an interesting plane, it would probably leave all of us behind. What speed and and RPM 's do you use for both long range and high speed cruise ? What are you approach and landing speeds ? Mike -------- "NO FEAR" - If you have no fear you did not go as fast as you could have !!! Kolb MK-III Xtra, 912-S Read this topic online here: http://forums.matronics.com/viewtopic.php?p=238698#238698 ________________________________ Message 5 _____________________________________ Time: 08:24:08 AM PST US Subject: Kolb-List: Re: V.W.conversion From: "Rick Lewis" The engine Great Plains offers is probably the way to go. The owner, Steve, has a good background on these engines and can offer most anything you'll need to make the engine perform. He is also presently working on his own version of the water cooled heads. Attached is a picture of my engine that I'm fitting up on my MXIII. The re-drive is a must for good performance and is well made. It cost around $1600.00. You will engine up with a good engine that should perform on your Kolb at only 1/3 the price of a Rotax, especially if you go with the water cooled heads. Rick Lewis Read this topic online here: http://forums.matronics.com/viewtopic.php?p=238708#238708 Attachments: http://forums.matronics.com//files/misc_pics_050_185.jpg http://forums.matronics.com//files/vw_engine_036_677.jpg ________________________________ Message 6 _____________________________________ Time: 08:42:44 AM PST US From: DAquaNut@aol.com Subject: Re: Kolb-List: Stits In a message dated 4/10/2009 8:20:23 P.M. Central Daylight Time, herbgh@nctc.com writes: A Firefly needs its fabric treated with a 50-50 mix of brush and spray...after the first coat of poly brush is applied in the normal way...and use 50-50 til you are satisfied that the uv protection is good... Two cross coats is good enough IMHO ... you are trying to make weight after all... and this stuff does add wt... the cost difference is because of the paper trail that certified fabric must have I think...mainly... Herb Herb, That sounds like a great idea! I wish I had heard that idea before I covered My Firefly! Has this process been tested for longevity in the sunlight ? How long has this process been proven to hold up in sunlight compared to the 3 full cross-coats Stits recommends ? Ed FF #62 ( In Houston ) **************Feeling the pinch at the grocery store? Make dinner for $10 or less. (http://food.aol.com/frugal-feasts?ncid=emlcntusfood00000001) ________________________________ Message 7 _____________________________________ Time: 08:58:53 AM PST US From: Herb Subject: Re: Kolb-List: Re: harmonics I am Rebuilding a C box...I notice that the input shaft and prop shaft both have spacers/shims ...They are important such that too much clearance will allow hammering with throttle changes...This will result in an accelerated wear factor which will gradually affect the case...or enclosure.and bearings and gear lash.......Herb At 07:50 AM 4/11/2009, you wrote: > >You mentioned that John H. mentioned the gear box spacers, this >makes several different people that I have heard mention this. The >others were not on the Kolb list, but it seems to be something >important with the 912. I am not sure what the symptom is if the >spacing is out of tolerance, but I will ask. The SS seems like an >interesting plane, it would probably leave all of us behind. What >speed and and RPM 's do you use for both long range and high speed >cruise ? What are you approach and landing speeds ? > >Mike > >-------- >"NO FEAR" - If you have no fear you did not go as fast as >you could have !!! > >Kolb MK-III Xtra, 912-S > > >Read this topic online here: > >http://forums.matronics.com/viewtopic.php?p=238698#238698 > > >Checked by AVG - www.avg.com >04/11/09 10:51:00 ________________________________ Message 8 _____________________________________ Time: 09:31:58 AM PST US From: "frank.goodnight" Subject: Re: Kolb-List: Re: V.W.conversion Hi Rick. good pictures . Who makes your redrive? Thanks for answering my question. Frank Goodnight Firestar2 HKS power On Apr 11, 2009, at 10:23 AM, Rick Lewis wrote: > > The engine Great Plains offers is probably the way to go. The > owner, Steve, has a good background on these engines and can offer > most anything you'll need to make the engine perform. He is also > presently working on his own version of the water cooled heads. > Attached is a picture of my engine that I'm fitting up on my MXIII. > The re-drive is a must for good performance and is well made. It > cost around $1600.00. You will engine up with a good engine that > should perform on your Kolb at only 1/3 the price of a Rotax, > especially if you go with the water cooled heads. > > Rick Lewis > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=238708#238708 > > > Attachments: > > http://forums.matronics.com//files/misc_pics_050_185.jpg > http://forums.matronics.com//files/vw_engine_036_677.jpg > > ________________________________ Message 9 _____________________________________ Time: 01:42:44 PM PST US From: "Richard & Martha Neilsen" Subject: Re: Kolb-List: Re: V.W.conversion Rick That is good news on the GP water-cooled heads. Do you have any details? Are they like yours? Do not archive Rick Neilsen Redrive VW powered MKIIIC ----- Original Message ----- From: "Rick Lewis" Sent: Saturday, April 11, 2009 11:23 AM Subject: Kolb-List: Re: V.W.conversion > > The engine Great Plains offers is probably the way to go. The owner, > Steve, has a good background on these engines and can offer most anything > you'll need to make the engine perform. He is also presently working on > his own version of the water cooled heads. Attached is a picture of my > engine that I'm fitting up on my MXIII. The re-drive is a must for good > performance and is well made. It cost around $1600.00. You will engine > up with a good engine that should perform on your Kolb at only 1/3 the > price of a Rotax, especially if you go with the water cooled heads. > > Rick Lewis > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=238708#238708 > > > Attachments: > > http://forums.matronics.com//files/misc_pics_050_185.jpg > http://forums.matronics.com//files/vw_engine_036_677.jpg > > > ________________________________ Message 10 ____________________________________ Time: 06:41:46 PM PST US From: "Jack B. Hart" Subject: Re: Kolb-List: Re: harmonics At 04:46 AM 4/11/09 -0700, you wrote: > >If the harmonic is coming from some airframe part and is a result of engine/prop vibrations, then the engine/prop vibrations being transmitted to this airframe part would be lessened if the mounts were a little softer. In any case a change in mount stiffness would change the natural harmonic frequency which might make the current troubling sound go away, go to a different pitch, go to a different part of the airframe or get worse. Difficult to predict. > .......................... Just to add a few thoughts. It all has to do with energy inputs. The greater the HP and the lighter (less stiff) the air frame the greater the chance is for harmonic vibrations to develop. Every air frame and or components will have some natural frequency. But there is an energy input threshold that must be passed before the frame will resonate that is related to structural stiffness. It is similar to unbalanced aileron flutter where a certain speed (energy level) must be reached before there is an onset of flutter. So what is the driving energy force? Well it is the engine and the propeller. They cause a twisting in the mounts directly proportional to the average torque being developed. Superimposed on top of the average torque is periodic torque variation that is caused by engine cylinder firing impulse. The amplitude variation is dependent upon torque resistance (springiness) of the crank shaft and crankshaft load. This load will be the gear box or propeller. As one increases crankshaft load more and more of the torque variation must be transferred to the engine mounts and dissapated though the supporting structure. So what are the choices? One could add more cylinders for a given average torque, and this would reduce the torque variation component magnitude so that will not exceed the airframe threshold. One can de couple the engine and propeller by moving to softer mounts. One can back off the throttle a little and reduce the torque variation amplitude, and in doing so miss match frequencies. This may also be accomplished by changing gear box ratios or changing the number of propeller blades. Another way to reduce the torque variation amplitude transmitted to the airframe is to add some kind of dampening in between the engine and the propeller. Also one can reduce inertial load seen by the crankshaft (less twisting). Just because an engine gear box or reduction unit can tolerate a certain level of propeller inertia does not mean that it is the correct or desired combination for all airframes. By lowering propeller inertia for the same power output means lower energy dissipation to the air frame. A more flexible the propeller will give further improvement, by absorbing some of the crank torque variation amplitude from the crank and there by not being passed on to the airframe. One last comment. On the FireFly, I had some noise problems. Streamlining the struts removed a constant bass strumming noise. The Victor 1+ being a one cylinder engine, it shakes things a bit. I found that it really excited the inboard aileron hinges. When I took all the play from the aileron hinges and control system, things became quieter. Also, I discovered the soft wing gap seal fluttered. Tube stiffeners in the front and rear cross seams to care of it. FWIW Jack B. Hart FF004 Winchester, IN ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message kolb-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Kolb-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/kolb-list Browse Digests http://www.matronics.com/digest/kolb-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.