---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Sat 12/10/05: 24 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:46 AM - Re: Trailers (Jim Ballenger) 2. 03:00 AM - Re: Trailers (Jim Ballenger) 3. 05:38 AM - Re: 912 vs 912S question (John Jung) 4. 05:51 AM - Firestar Hauling... (David Lehman) 5. 06:19 AM - Re: Trailers (Larry Bourne) 6. 07:34 AM - Re: Thrust line change (Jack B. Hart) 7. 07:40 AM - Re: Thrust line change (Richard Pike) 8. 09:26 AM - Re:Firestar Hauling... (Mike Pierzina) 9. 09:29 AM - Re: Trailers (Larry Cottrell) 10. 09:32 AM - Re: Thrust line change (Jack B. Hart) 11. 10:11 AM - Re: Trailers (Jim Ballenger) 12. 10:59 AM - Re: Trailers (bryan green) 13. 11:05 AM - Re: Trailers (Dave & Eve Pelletier) 14. 12:14 PM - Re: 912 vs 912S question (roger lee) 15. 12:20 PM - Re: Thrust line change (roger lee) 16. 12:37 PM - Re: Trailers (George T. Alexander, Jr.) 17. 01:15 PM - Re: Thrust line change (Christopher Armstrong) 18. 01:48 PM - ROTAX 582 JET NEEDLE ADJUSTMENT/RADIATOR TIPS/ELECTRIC VEST TESTIMONIAL (Jim Ballenger) 19. 02:54 PM - Re: Thrust line change (Richard Pike) 20. 03:37 PM - Re: Thrust line change (John Hauck) 21. 06:54 PM - Re: Trailers (GeoR38@aol.com) 22. 06:58 PM - Re: Trailers (Larry Bourne) 23. 08:07 PM - Re: Thrust line change (Richard Pike) 24. 08:28 PM - Re: Thrust line change (John Hauck) ________________________________ Message 1 _____________________________________ Time: 02:46:08 AM PST US From: "Jim Ballenger" Subject: Re: Kolb-List: Trailers --> Kolb-List message posted by: "Jim Ballenger" Chris Thanks, looking forward to the pictures. Jim Ballenger MK III X 582 Virginia Beach, VA Do Not Archive ----- Original Message ----- From: "Chris Mallory" Subject: Re: Kolb-List: Trailers > --> Kolb-List message posted by: "Chris Mallory" > > Jim, > I will take some pictures of the ramp set up tomorrow and send them to > you. > Basicly, it's just pressure treated 2X6 or 2x8 cut to a taper on both ends > with some shelving track from Home Depot screwed to the top of it for the > tail wheel to track in. It works great. > > Chris Mallory > > > ----- Original Message ----- > From: "Jim Ballenger" > To: > Subject: Re: Kolb-List: Trailers > > >> --> Kolb-List message posted by: "Jim Ballenger" >> >> Chris >> I am interested in the ramp you have put in the center of the trailer. >> Do >> you have a picture you could send me? I had a FS KXP that I kept in the >> trailer and had to take the wheels off the trailer and raise the tongue >> in >> order to prevent from scraping the LE of the folded wings when >> unloading/loading down my ramp door. >> Thanks >> Jim Ballenger >> MK III X 582 >> Virginia Beach, VA >> >> Do Not Archive >> ----- Original Message ----- >> From: "Chris Mallory" >> To: >> Subject: Re: Kolb-List: Trailers >> >> >>> --> Kolb-List message posted by: "Chris Mallory" >>> >>> lucien, >>> >>> I have a 24 ft. Haulmark that I keep my FSII in and it's been great, a >>> lot >>> of room inside. It's pretty heavy (3800 lbs) although it pulls nicely. I >>> would not recommend that you try to pull it with anything small however. >>> >>> You also have to make a "ramp" down the center of the trailer (inside) >>> to >>> keep the leading edge of the wings from being scraped when loading and >>> unloading due to the angle change. >>> >>> I also have a small (2500 lb) ATV winch mounted in mine so all you have >>> to >>> do is set the tail wheel on the ramp, hook it up and push a button. >>> >>> If you decide to go that way I would be happy to show you more of what >>> I've >>> done to mine to accommodate the Firestar II. >>> >>> Photo enclosed. >>> >>> Chris Mallory >>> >>> DO NOT ARCHIVE >>> >>> >>> >> >> >> > > > ________________________________ Message 2 _____________________________________ Time: 03:00:10 AM PST US From: "Jim Ballenger" Subject: Re: Kolb-List: Trailers --> Kolb-List message posted by: "Jim Ballenger" Ed Thanks for the info. I ,too, had a dolly that I used, but I still ended up scraping the LE of the wing. Jim Ballenger MK III X 582 Virginia Beach, VA Do Not Archive ----- Original Message ----- From: Subject: Re: Kolb-List: Trailers > --> Kolb-List message posted by: DAquaNut@aol.com > > > In a message dated 12/9/2005 1:00:02 P.M. Central Standard Time, > ulpilot@cavtel.net writes: > > I am interested in the ramp you have put in the center of the trailer. > Do > you have a picture you could send me? I had a FS KXP that I kept in the > trailer and had to take the wheels off the trailer and raise the tongue > in > order to prevent from scraping the LE of the folded wings when > unloading/loading down my ramp door. > Thanks > Jim Ballenger > > > Jim, > > I built a dolly for my Firefly that cradles the tail wheel axle . It > raises the tail wheel about a foot or so. This gives good clearance at > the back > where I need it most. The dolly holds the axle to where I can push the > plane > up the incline of the tilted trailer. the dolly can be made to lift the > tail > to what ever height you need. You might consider the advantage of using a > dolly to gain a little height. I couldn't make it without mine. > > Ed > > > ________________________________ Message 3 _____________________________________ Time: 05:38:55 AM PST US From: John Jung Subject: Re: Kolb-List: 912 vs 912S question --> Kolb-List message posted by: John Jung Jack Hart and Group, Thanks to all that answered my 912 912S question. Jack Hart had the best answer by pointing out another source. It appears to me after comparing the fuel burn charts for the two engines, that Kodiak Research has a completely wrong fuel burn chart posted for the 912UL. The chart on the rotax-aircraft-engines site makes a lot more sense. John Jung Firestar II N6163J Surprise, AZ do not archive > Try the charts found on: > http://www.rotax-aircraft-engines.com/ ________________________________ Message 4 _____________________________________ Time: 05:51:27 AM PST US From: David Lehman Subject: Kolb-List: Firestar Hauling... --> Kolb-List message posted by: David Lehman Just when I thought I was smarter than the average bear and had this all figured out... I'm questioning my tail support... What is the distance from the leading edge of the wing to the bottom of the tail boom in the area forward of the tail with the wings folded?... If this was answered before, I'm sorry, I can't find it now... Less than two weeks before I pick her up, yeah, I'm excited!... Thanx... David ________________________________ Message 5 _____________________________________ Time: 06:19:32 AM PST US From: "Larry Bourne" Subject: Re: Kolb-List: Trailers --> Kolb-List message posted by: "Larry Bourne" Jim, I'm not sure this is what you're looking for, but John Wood very neatly solved the leading edge problem in the trailer I bought from him. I had to modify it a bit to work with my truck, but it works very well. Take a look at my web page: www.biglar.homestead.com/landing.html I also have a winch in the front to pull my heavier Mk III up the slope. Lar. Larry Bourne Palm Springs, CA Building Kolb Mk III N78LB Vamoose www.gogittum.com ----- Original Message ----- From: "Jim Ballenger" Subject: Re: Kolb-List: Trailers > --> Kolb-List message posted by: "Jim Ballenger" > > Chris > I am interested in the ramp you have put in the center of the trailer. Do > you have a picture you could send me? I had a FS KXP that I kept in the > trailer and had to take the wheels off the trailer and raise the tongue in > order to prevent from scraping the LE of the folded wings when > unloading/loading down my ramp door. > Thanks > Jim Ballenger > MK III X 582 > Virginia Beach, VA ________________________________ Message 6 _____________________________________ Time: 07:34:40 AM PST US From: "Jack B. Hart" Subject: RE: Kolb-List: Thrust line change --> Kolb-List message posted by: "Jack B. Hart" Kolbers, With the Victor 1+ belt reduction drive, it was possible to investigate what would happen if the thrust line was lowered. Using the same propeller setting and cruise rpm, the FireFly picked up about 0.6 mph for each inch the thrust line was lowered. You can check out how it was done at: http://www.thirdshift.com/jack/firefly/firefly56.html Also, I made some assumptions and calculated the change in FireFly wing and tail loads as the thrust line was changed. I guessed that the center of drag passed through the trailing wing attachment point and I assumed a CG near the aft limit. These calculations indicate that for level and for flight under identical conditions, for every inch the thrust line was lowered about one pound came off the wing and the tail. Also, if you move the CG forward the forward limit, lowering the thrust line is more productive. How it was done can be seen at: http://www.thirdshift.com/jack/firefly/firefly101.html I guessed at the center drag position. It seems that if the Firefly is symmetrical, the center of drag should be on the vertical center line. One way to get a better first guess would be to draw up the scaled front view profile, print it out on paper, cut out the profile and balance it on the point of a pin along a vertical line through the central axis. The balance point will be the center of flat plate drag. Scaling this point back up to real size should give a first guess as to where the actual center of drag is on the FireFly. Drove by the airport. They have plowed the apron and runways, but they have not plowed the taxi ways to and in between the hangars. The FireFly hangar doors are snowed shut. So today, it might be a good day to draw a front FireFly profile. Jack B. Hart FF004 Winchester, IN ________________________________ Message 7 _____________________________________ Time: 07:40:53 AM PST US From: Richard Pike Subject: RE: Kolb-List: Thrust line change --> Kolb-List message posted by: Richard Pike Got a question on your post, especially the last sentence - physically raising the engine too much relative to the airframe will obviously sooner or later get things to the point that the thrust line moment would overpower the control authority of the elevators, but I am considering shimming the rearmost motor mounts to raise the prop end of the engine. The goal is to reduce the need to retrim elevator pressure with changes in throttle settings. My thinking is, when the forward end of the engine is too high relative to the chordline of the wing, then the thrust line relative to both the center of drag and the center of mass requires various amounts of up elevator to counteract as throttle settings change. Because the thrust is trying to push the nose down. Raising the rear of the engine so that the thrust vector goes through the chordline of the wing ought to give opposite results, and surely does up to a point, but as I read your post, apparently you get to a place where changing the thrust vector to improve elevator pressure ceases to be helpful and only adds wierd side effects. Or are you talking thrust moment arm, and I am applying it to thrust vector angles? Or did I miss something? (Always likely...) Advice welcome - Thanks Richard Pike MKIII N420P (420ldPoops) At 12:16 AM 12/10/2005, you wrote: >--> Kolb-List message posted by: "Christopher Armstrong" > > >The pitching moment due to thrust is the thrust times >the moment arm to the cg, not the Aero center. (Drag adds its moment as >drag times its moment arm to the cg but it doesn't change with thrust >setting, only with speed.) To change the thrust moment arm significantly >would require so much angle to get the effect you want that it would be >terrible for prop efficiency ( not to mention result in yaw due to the >higher aoa and velocity on the prop on one side of the plane versus the >other, p-factor in cruise is a very bad thing). The engine is fairly close >to the CG front to back so you would have to tilt the engine many degrees to >reduce the thrust line moment arm significantly. If the engine was farther >back then only a bit of angle change would reduce the thrust moment arm much >more. If you raise the engine too much the plane will not have enough pitch >control to overcome the pitch due to thrust and you will not be able to >rotate or climb. > > ________________________________ Message 8 _____________________________________ Time: 09:26:44 AM PST US From: Mike Pierzina Subject: Kolb-List: RE:Firestar Hauling... --> Kolb-List message posted by: Mike Pierzina I'm questioning my tail support... What is the distance from the leading edge of the wing to the bottom of the tail boom in the area forward of the tail with the wings folded?... If this was answered before, I'm sorry, I can't find it now... Less than two weeks before I pick her up, yeah, I'm excited!... Thanx... David >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> Hi David, I measured mine...which is "stock" and the distance is 13" exactly That's forward of the empanage....from the bottom of the boom tube, to the wings leading edge in the folded position.... Gotta Fly... do not archive Firestar I&II Forum http://groups.yahoo.com/group/Kolb_Firestar/ Airplane Building Forum http://groups.yahoo.com/group/up_yerz/ My Web Site: http://www.geocities.com/planecrazzzy/Planecrazzzy.html Sometimes you just have to take the leap and build your wings on the way down... --------------------------------- ________________________________ Message 9 _____________________________________ Time: 09:29:20 AM PST US From: "Larry Cottrell" Subject: Re: Kolb-List: Trailers --> Kolb-List message posted by: "Larry Cottrell" ----- Original Message ----- From: "Jim Ballenger" Subject: Re: Kolb-List: Trailers > --> Kolb-List message posted by: "Jim Ballenger" > > Ed > Thanks for the info. I ,too, had a dolly that I used, but I still ended > up > scraping the LE of the wing. > Jim Ballenger > MK III X 582 > Virginia Beach, VA I notice that most of these trailers are single axle to reduce the weight. If you do have a single axle trailer, then it is just a matter of unhooking the trailer from the towing vehicle and raising the front of the trailer to a point where you can wheel the plane out without scraping the leading edge. I have a jack that I made out of a piece of 1 inch square steel that I use to raise and hold the trailer at the angle that I need. The trailer is designed so that there is about 100 lbs tongue weight. ( Most will be close to that ) With mine the door covers the whole end of the trailer and when it is folded down I use it for a ramp to push the plane up. With the Firestar I can hand push it into the trailer with no problem. The problem is not that difficult, you need to have ramps long enough to get it into the trailer or the trailer angled enough that the LE does not scrape. If anyone has welding skills the jack is easy to make, and you can make it long enough that it will put the rear edge of the trailer down on the ground if that is what you want. I can take pictures of the jack if you want. Do not archive Larry, Oregon ________________________________ Message 10 ____________________________________ Time: 09:32:51 AM PST US From: "Jack B. Hart" Subject: RE: Kolb-List: Thrust line change --> Kolb-List message posted by: "Jack B. Hart" At 11:16 PM 12/9/05 -0600, you wrote: >--> Kolb-List message posted by: "Christopher Armstrong" > more. If you raise the engine too much the plane will not have enough pitch >control to overcome the pitch due to thrust and you will not be able to >rotate or climb. Chris & Richard, I have seen evidence of this with my FireFly. If I tease it off with three degrees of flaperon and stick back against the stop, the FireFly will fly off very nicely at minimum speed. But if I get aggressive with the throttle while using the same stick back and flaperon setting, the FireFly will accelerate well past minimum flight speed but it will not break loose until I drop the throttle back. Jack B. Hart FF004 Winchester, IN ________________________________ Message 11 ____________________________________ Time: 10:11:02 AM PST US From: "Jim Ballenger" Subject: Re: Kolb-List: Trailers --> Kolb-List message posted by: "Jim Ballenger" Larry B / Larry C Thanks for the information. I looked at your web site Larry B and see what your talking about. It looks like what Larry C is describing. Looks like a neat rig you have. I have sold my FS and trailer a couple of months ago. I have a hangar for the MK III X which really makes going flying an easy decision, but I will need a trailer in the future and will incorporate your ideas. Thanks Jim Ballenger MK III X 582 Virginia Beach, VA Do Not Archive ----- Original Message ----- From: "Larry Bourne" Subject: Re: Kolb-List: Trailers > --> Kolb-List message posted by: "Larry Bourne" > > Jim, I'm not sure this is what you're looking for, but John Wood very > neatly > solved the leading edge problem in the trailer I bought from him. I had > to > modify it a bit to work with my truck, but it works very well. Take a > look > at my web page: www.biglar.homestead.com/landing.html I also have a > winch in the front to pull my heavier Mk III up the slope. > Lar. > > Larry Bourne > Palm Springs, CA > Building Kolb Mk III > N78LB Vamoose > www.gogittum.com > > ----- Original Message ----- > From: "Jim Ballenger" > To: > Subject: Re: Kolb-List: Trailers > > >> --> Kolb-List message posted by: "Jim Ballenger" >> >> Chris >> I am interested in the ramp you have put in the center of the trailer. >> Do >> you have a picture you could send me? I had a FS KXP that I kept in the >> trailer and had to take the wheels off the trailer and raise the tongue >> in >> order to prevent from scraping the LE of the folded wings when >> unloading/loading down my ramp door. >> Thanks >> Jim Ballenger >> MK III X 582 >> Virginia Beach, VA > > > ________________________________ Message 12 ____________________________________ Time: 10:59:09 AM PST US From: bryan green Subject: Re: Kolb-List: Trailers --> Kolb-List message posted by: bryan green Larry Cottrell wrote: >--> Kolb-List message posted by: "Larry Cottrell" > > >----- Original Message ----- >From: "Jim Ballenger" >To: >Subject: Re: Kolb-List: Trailers > > > > >>--> Kolb-List message posted by: "Jim Ballenger" >> >>Ed >>Thanks for the info. I ,too, had a dolly that I used, but I still ended >>up >>scraping the LE of the wing. >>Jim Ballenger >>MK III X 582 >>Virginia Beach, VA >> >> > > >I notice that most of these trailers are single axle to reduce the weight. >If you do have a single axle trailer, then it is just a matter of unhooking >the trailer from the towing vehicle and raising the front of the trailer to >a point where you can wheel the plane out without scraping the leading edge. > > >Larry, Oregon > > >This works just fine with my double axle trailer also Larry. > > Bryan Green Elgin SC Do not archive ________________________________ Message 13 ____________________________________ Time: 11:05:51 AM PST US From: "Dave & Eve Pelletier" Subject: Re: Kolb-List: Trailers --> Kolb-List message posted by: "Dave & Eve Pelletier" > I have a jack that I made out of a piece of 1 inch square steel that I use > to raise and hold the trailer at the angle that I need. If anyone has welding > skills the jack is easy to make, and you can make it long enough that it > will put the rear edge of the trailer down on the ground if that is what > you > want. I can take pictures of the jack if you want. > Do not archive > > Larry, Oregon Or you can buy a "Bulldog" brand jack. Mine costs about $80. I had it welded to the tongue and cut the crank handle off. Then welded a long (about 2") 5/8" nut to the remaining shank. (I think these nuts are used to tighten cables - y'know, threaded at both ends.) My 18V battery drill with a 5/8" socket runs it up and down like an electric jack. Slicker'n deer guts on a pump handle. I welded another 5/8" socket to the end of the cut off crank handle to use in case the drill battery runs down - haven't had to use it yet. The best feature about the "Bulldog" jack is that it telescopes down so you can get the jack all the way down to the ground before you start cranking it down. That way you can get the nose of the trailer much higher than if you just have a standard trailer jack. (I used to have to stack 2x6's under my standard trailer jack to get the nose high enough.) I got my jack at a trailer supply place that caters to horse and cattle trailer. AzDave Do Not Archive ________________________________ Message 14 ____________________________________ Time: 12:14:24 PM PST US From: roger lee Subject: Re: Kolb-List: 912 vs 912S question --> Kolb-List message posted by: roger lee Hi John, I have a 912URLs on my Mark III Classic. I have checked my fuel burn many times and it has always remained the same. The one thing I really didn't see was a mention of the prop size and the pitch setting, which would change the burn rate some. I run my 912s at about 4900 rpm at an airspeed of 80 mph and I get a 4 gph burn. I also have a 68" Warp Drive 3 Blade prop on my engine.This set up seems to run very smooth without any vibrations. My prop is set up for cruise and I see 5500 rpm at max power. The fuel burn is very consistent. I could set my prop to see higher rpm, but why do it with all the power I already have and need. Just my 2 cents Roger Lee Tucson, AZ John Jung wrote: --> Kolb-List message posted by: John Jung Jack Hart and Group, Thanks to all that answered my 912 912S question. Jack Hart had the best answer by pointing out another source. It appears to me after comparing the fuel burn charts for the two engines, that Kodiak Research has a completely wrong fuel burn chart posted for the 912UL. The chart on the rotax-aircraft-engines site makes a lot more sense. John Jung Firestar II N6163J Surprise, AZ do not archive > Try the charts found on: > http://www.rotax-aircraft-engines.com/ --------------------------------- ________________________________ Message 15 ____________________________________ Time: 12:20:06 PM PST US From: roger lee Subject: RE: Kolb-List: Thrust line change --> Kolb-List message posted by: roger lee Hi All, Just to let everyone know that Kolb has new horizontal stabilizer brackets that have a 4 position adjustment set up for trim. These new brackets take the place of the old stainless steel "L" brackets up front on the horizontal stabilizer. I just ordered a set so I will let you all know very soon. Right now I have to use too much trim to keep the nose of my Mark III Classic level. My nose wants to pitch down with the way they have it set up now. Roger Lee Tucson, AZ Richard Pike wrote: --> Kolb-List message posted by: Richard Pike Got a question on your post, especially the last sentence - physically raising the engine too much relative to the airframe will obviously sooner or later get things to the point that the thrust line moment would overpower the control authority of the elevators, but I am considering shimming the rearmost motor mounts to raise the prop end of the engine. The goal is to reduce the need to retrim elevator pressure with changes in throttle settings. My thinking is, when the forward end of the engine is too high relative to the chordline of the wing, then the thrust line relative to both the center of drag and the center of mass requires various amounts of up elevator to counteract as throttle settings change. Because the thrust is trying to push the nose down. Raising the rear of the engine so that the thrust vector goes through the chordline of the wing ought to give opposite results, and surely does up to a point, but as I read your post, apparently you get to a place where changing the thrust vector to improve elevator pressure ceases to be helpful and only adds wierd side effects. Or are you talking thrust moment arm, and I am applying it to thrust vector angles? Or did I miss something? (Always likely...) Advice welcome - Thanks Richard Pike MKIII N420P (420ldPoops) At 12:16 AM 12/10/2005, you wrote: >--> Kolb-List message posted by: "Christopher Armstrong" > > >The pitching moment due to thrust is the thrust times >the moment arm to the cg, not the Aero center. (Drag adds its moment as >drag times its moment arm to the cg but it doesn't change with thrust >setting, only with speed.) To change the thrust moment arm significantly >would require so much angle to get the effect you want that it would be >terrible for prop efficiency ( not to mention result in yaw due to the >higher aoa and velocity on the prop on one side of the plane versus the >other, p-factor in cruise is a very bad thing). The engine is fairly close >to the CG front to back so you would have to tilt the engine many degrees to >reduce the thrust line moment arm significantly. If the engine was farther >back then only a bit of angle change would reduce the thrust moment arm much >more. If you raise the engine too much the plane will not have enough pitch >control to overcome the pitch due to thrust and you will not be able to >rotate or climb. > > --------------------------------- ________________________________ Message 16 ____________________________________ Time: 12:37:40 PM PST US From: "George T. Alexander, Jr." Subject: RE: Kolb-List: Trailers --> Kolb-List message posted by: "George T. Alexander, Jr." Kolbers: With the apparent high interest in the various methods used for trailers and Kolbs, those of you who have trailers, who want to, can send me pictures that show your particular setup. A few descriptive words for each picture. I will create a web page to show them. I have pictures of Steven Green's dolly now and Chris Mallory is going to send me his pictures to be added to the "Trailering a Kolb". Don't intend to replace the Photoshare Section of the Kolb list, but since there has been such a show of interest, I thought it merits putting some of this stuff in one, easily referenced place. George Alexander http://gtalexander.home.att.net DO NOT ARCHIVE ________________________________ Message 17 ____________________________________ Time: 01:15:18 PM PST US From: "Christopher Armstrong" Subject: RE: Kolb-List: Thrust line change --> Kolb-List message posted by: "Christopher Armstrong" Just changing the thrust angle itself does not change the pitching moment due to thrust, you must change the thrust moment arm to the cg. If you moved the engine up and tilted it at the same time to keep a constant moment arm to the cg then there would be no pitching moment due to thrust change. Tilting alone will change the pitching moment due to thrust by however much the moment arm changes. Unfortunately the cg of a Kolb is close to the engine. On a plane with the engine ten feet from the cg you could get a big change by tilting the engine a bit, but on a Kolb it is maybe 2 feet away. So spinning the engine a bit does not change the moment arm much. If the engine were on the cg then you could spin it all over and it would not change PM at all. There would be no pitching moment due to thrust! Course if you pointed the engine straight up (thrust straight down) there would be no thrust in the direction that you want either! In cruise flight you want the thrust pointed directly forward. If you don't then you end up shoving the plane sideways (well downways) through the air. If the plane is being shoved downwards through the air the wing and tail will be at different angles of attack and their contributions to pitching moment will change. So even if you didn't get a change in pitching moment due to thrust, turning the engine will result in a different total pitching moment, due to the wing, tail and fuselage going through the wind at a slightly different angle. All of you know you don't want to fly around in a sideslip, cause the plane just flys bad. Well you don't want to fly around with downslip or upslip either. The plane will be inefficient. The fuselage is designed (term used loosely when referring to a Kolb fuselage, they basically are cages that fit around the people and hard points, not very aerodynamic!) to fly through the air at cruise at a specific angle, and the wings, engine and tail are mounted on the fuselage to let the fuselage to fly at that angle in cruise, and the prop is designed to be perpendicular to the wind at that angle. If you tilt the engine more then a few degrees all of this will get screwed up and the plane will downslip or upslip. Would you fly around with the engine tilted to one side more then about 3 degrees, and force the plane to fly around in a sideslip? I don't think so. Christopher Armstrong -----Original Message----- From: owner-kolb-list-server@matronics.com [mailto:owner-kolb-list-server@matronics.com] On Behalf Of Richard Pike Subject: RE: Kolb-List: Thrust line change --> Kolb-List message posted by: Richard Pike Got a question on your post, especially the last sentence - physically raising the engine too much relative to the airframe will obviously sooner or later get things to the point that the thrust line moment would overpower the control authority of the elevators, but I am considering shimming the rearmost motor mounts to raise the prop end of the engine. The goal is to reduce the need to retrim elevator pressure with changes in throttle settings. My thinking is, when the forward end of the engine is too high relative to the chordline of the wing, then the thrust line relative to both the center of drag and the center of mass requires various amounts of up elevator to counteract as throttle settings change. Because the thrust is trying to push the nose down. Raising the rear of the engine so that the thrust vector goes through the chordline of the wing ought to give opposite results, and surely does up to a point, but as I read your post, apparently you get to a place where changing the thrust vector to improve elevator pressure ceases to be helpful and only adds wierd side effects. Or are you talking thrust moment arm, and I am applying it to thrust vector angles? Or did I miss something? (Always likely...) Advice welcome - Thanks Richard Pike MKIII N420P (420ldPoops) At 12:16 AM 12/10/2005, you wrote: >--> Kolb-List message posted by: "Christopher Armstrong" > > >The pitching moment due to thrust is the thrust times >the moment arm to the cg, not the Aero center. (Drag adds its moment as >drag times its moment arm to the cg but it doesn't change with thrust >setting, only with speed.) To change the thrust moment arm significantly >would require so much angle to get the effect you want that it would be >terrible for prop efficiency ( not to mention result in yaw due to the >higher aoa and velocity on the prop on one side of the plane versus the >other, p-factor in cruise is a very bad thing). The engine is fairly close >to the CG front to back so you would have to tilt the engine many degrees to >reduce the thrust line moment arm significantly. If the engine was farther >back then only a bit of angle change would reduce the thrust moment arm much >more. If you raise the engine too much the plane will not have enough pitch >control to overcome the pitch due to thrust and you will not be able to >rotate or climb. > > ________________________________ Message 18 ____________________________________ Time: 01:48:22 PM PST US From: "Jim Ballenger" Subject: Kolb-List: ROTAX 582 JET NEEDLE ADJUSTMENT/RADIATOR TIPS/ELECTRIC VEST TESTIMONIAL --> Kolb-List message posted by: "Jim Ballenger" All A couple of weeks ago when the weather got cold here in Virginia I had trouble getting a satisfactory mag check. The manual states to run up to 3500 rpm and check each mag for no more than 300 rpm drop. During the hot summer months I was able to get good mag check with my needle set in the lowest position on my 582 blue head. When the temperature dropped into the upper thirties/lower forties I could not get my engine to turn more than 3000 rpm before it would bog down. I used the choke and it would turn up to 4000 rpm. Armed with that information I called Lockwood Aviation and they advised me to raise the needle in the carbs. I put my clip in the third notch from the top and it runs great. This is the first water cooled 2 stroke rotax I have owned and I am finding it somewhat different to tune than my prior 277/377/447 air cooled engines. I have also found out in the cold weather that I needed to install about 4 " of aluminum sheeting on the face of each radiator to keep the water temperature at least 150 degrees. This morning the OAT was 32 and I was able to keep my water temp at 152 with 5800 rpm. Since I have an electrical system on the MK III X and I had an electric vest left over from my motorcycling days, I took John Hauck's advise and hooked up the vest to the battery. What a great easy way to stay warm without all the hassles of installing a heater system. With the thermostat on 0/1 position I was warm and my voltage meter indicated a 13.2 volts so the vest did not take prevent the battery from being charged while I was flying. Thanks John. Jim Ballenger MK III X 582 Virginia Beach, VA ________________________________ Message 19 ____________________________________ Time: 02:54:48 PM PST US From: Richard Pike Subject: RE: Kolb-List: Thrust line change --> Kolb-List message posted by: Richard Pike OK, we are on the same page. What you said is what I thought, so we agree. Question is, if the plane is in an upslip or downslip, then I would think a throttle setting change would change the stick pressure needed to maintain level flight - Consequently, what we need to do is accurately determine the angle of the wing relative to the airflow at level cruise. This could likely be done using a level and a set of marks, etc. Once this is properly determined, then we determine if the prop is vertical. Then we go from there. Richard Pike MKIII N420P (420ldPoops) At 04:14 PM 12/10/2005, you wrote: >--> Kolb-List message posted by: "Christopher Armstrong" > > >Just changing the thrust angle itself does not change the pitching moment >due to thrust, you must change the thrust moment arm to the cg. If you >moved the engine up and tilted it at the same time to keep a constant moment >arm to the cg then there would be no pitching moment due to thrust change. >Tilting alone will change the pitching moment due to thrust by however much >the moment arm changes. Unfortunately the cg of a Kolb is close to the >engine. On a plane with the engine ten feet from the cg you could get a big >change by tilting the engine a bit, but on a Kolb it is maybe 2 feet away. >So spinning the engine a bit does not change the moment arm much. If the >engine were on the cg then you could spin it all over and it would not >change PM at all. There would be no pitching moment due to thrust! Course >if you pointed the engine straight up (thrust straight down) there would be >no thrust in the direction that you want either! In cruise flight you want >the thrust pointed directly forward. If you don't then you end up shoving >the plane sideways (well downways) through the air. If the plane is being >shoved downwards through the air the wing and tail will be at different >angles of attack and their contributions to pitching moment will change. So >even if you didn't get a change in pitching moment due to thrust, turning >the engine will result in a different total pitching moment, due to the >wing, tail and fuselage going through the wind at a slightly different >angle. > >All of you know you don't want to fly around in a sideslip, cause the plane >just flys bad. Well you don't want to fly around with downslip or upslip >either. The plane will be inefficient. The fuselage is designed (term used >loosely when referring to a Kolb fuselage, they basically are cages that fit >around the people and hard points, not very aerodynamic!) to fly through the >air at cruise at a specific angle, and the wings, engine and tail are >mounted on the fuselage to let the fuselage to fly at that angle in cruise, >and the prop is designed to be perpendicular to the wind at that angle. If >you tilt the engine more then a few degrees all of this will get screwed up >and the plane will downslip or upslip. Would you fly around with the engine >tilted to one side more then about 3 degrees, and force the plane to fly >around in a sideslip? I don't think so. > > >Christopher Armstrong > > >-----Original Message----- >From: owner-kolb-list-server@matronics.com >[mailto:owner-kolb-list-server@matronics.com] On Behalf Of Richard Pike >To: kolb-list@matronics.com >Subject: RE: Kolb-List: Thrust line change > >--> Kolb-List message posted by: Richard Pike > >Got a question on your post, especially the last sentence - >physically raising the engine too much relative to the airframe will >obviously sooner or later get things to the point that the thrust >line moment would overpower the control authority of the elevators, >but I am considering shimming the rearmost motor mounts to raise the >prop end of the engine. The goal is to reduce the need to retrim >elevator pressure with changes in throttle settings. > >My thinking is, when the forward end of the engine is too high >relative to the chordline of the wing, then the thrust line relative >to both the center of drag and the center of mass requires various >amounts of up elevator to counteract as throttle settings change. >Because the thrust is trying to push the nose down. > >Raising the rear of the engine so that the thrust vector goes through >the chordline of the wing ought to give opposite results, and surely >does up to a point, but as I read your post, apparently you get to a >place where changing the thrust vector to improve elevator pressure >ceases to be helpful and only adds wierd side effects. > >Or are you talking thrust moment arm, and I am applying it to thrust >vector angles? Or did I miss something? (Always likely...) Advice welcome - > >Thanks >Richard Pike >MKIII N420P (420ldPoops) > >At 12:16 AM 12/10/2005, you wrote: > >--> Kolb-List message posted by: "Christopher Armstrong" > > > > > >The pitching moment due to thrust is the thrust times > >the moment arm to the cg, not the Aero center. (Drag adds its moment as > >drag times its moment arm to the cg but it doesn't change with thrust > >setting, only with speed.) To change the thrust moment arm significantly > >would require so much angle to get the effect you want that it would be > >terrible for prop efficiency ( not to mention result in yaw due to the > >higher aoa and velocity on the prop on one side of the plane versus the > >other, p-factor in cruise is a very bad thing). The engine is fairly close > >to the CG front to back so you would have to tilt the engine many degrees >to > >reduce the thrust line moment arm significantly. If the engine was farther > >back then only a bit of angle change would reduce the thrust moment arm >much > >more. If you raise the engine too much the plane will not have enough >pitch > >control to overcome the pitch due to thrust and you will not be able to > >rotate or climb. > > > > > > ________________________________ Message 20 ____________________________________ Time: 03:37:03 PM PST US From: "John Hauck" Subject: Re: Kolb-List: Thrust line change --> Kolb-List message posted by: "John Hauck" | determined, then we determine if the prop is vertical. Then we go from there. | | Richard Pike Richard/Gang: Another factor you must determine is how much the pitch attitude the engine is going to change from dead engine on the ground to cruise power in the air. The Lord Mounts will allow the engine to push down some in the front and up some in the rear. Will also cock the engine a little as the result of torque. I never realized how much until I was observing the 447 on my Firestar, tied down and increasing and decreasing power. The engine changes attitude from stop to different power settings quite a bit, thus thrust angle. I've started playing around with this way back in FS days. For the MKIII with 912ULS, I raise the front of the engine 5/8". This puts the angle of the prop 90 deg to the bottom of the wing when the engine is off. Just guessing, but I figure the rear of the engine is going to come up a bit and the front down just a tad under cruise power, or about right to give me a thrust line that is parallel to relative wind. I check this with my old eye ball by looking at the wing tip in relation to the horizon in straight and level flight at cruise power. Is it exact? I doubt it, but I think it is more in line with what I am looking for than leaving the engine level on the engine mounts as designed. A good example of what our Kolbs are doing when we push the throttle forward with an engine at high thrust line is about the same, to me, as pushing a lawn mower in thick grass with small wheels. The harder we push horizontally on the high position of the handle, the more the front wheels of the mower get loaded up and the lighter the rear wheels, to the point of them coming right off the lawn and tipping up the rear. I believe that is exactly what we are experiencing with our Kolbs. Do I have numbers, diagrams, bell curves, slide rules, and backing by Kolb Aircraft? Nope. Just a lot of hours flying, tinkering, experimenting, and playing with my Kolbs. john h MKIII/912ULS hauck's holler, alabama ________________________________ Message 21 ____________________________________ Time: 06:54:42 PM PST US From: GeoR38@aol.com Subject: Re: Kolb-List: Trailers --> Kolb-List message posted by: GeoR38@aol.com In a message dated 12/10/2005 2:06:17 P.M. Eastern Standard Time, pelletier@cableone.net writes: Slicker'n deer guts on a pump handle. do I detect another "classic" here? George Randolph Firestar driver from The Villages, Fl Rotax 447, 3 blade Ivo, KX, 1991 Do not Archive ________________________________ Message 22 ____________________________________ Time: 06:58:36 PM PST US From: "Larry Bourne" Subject: Re: Kolb-List: Trailers --> Kolb-List message posted by: "Larry Bourne" Hi George: If you're interested in any of mine, you can pick 'em off the web page, or, if you prefer, tell me which ones you want and I'll email them to you. Lar. Do not Archive. Larry Bourne Palm Springs, CA Building Kolb Mk III N78LB Vamoose www.gogittum.com ----- Original Message ----- From: "George T. Alexander, Jr." Subject: RE: Kolb-List: Trailers > --> Kolb-List message posted by: "George T. Alexander, Jr." > > > Kolbers: > With the apparent high interest in the various methods used for trailers > and > Kolbs, those of you who have trailers, who want to, can send me pictures > that show your particular setup. A few descriptive words for each picture. > I ________________________________ Message 23 ____________________________________ Time: 08:07:56 PM PST US From: Richard Pike Subject: Re: Kolb-List: Thrust line change --> Kolb-List message posted by: Richard Pike What would you say the angle of the bottom of your wing is relative to the horizon while in straight and level flight? Richard Pike MKIII N420P (420ldPoops) do not archive At 06:37 PM 12/10/2005, you wrote: >--> Kolb-List message posted by: "John Hauck" > >I check this with my old eye ball by looking at the >wing tip in relation to the horizon in straight and level flight at >cruise power. Is it exact? I doubt it, but I think it is more in >line with what I am looking for than leaving the engine level on the >engine mounts as designed. > john h >MKIII/912ULS >hauck's holler, alabama > > ________________________________ Message 24 ____________________________________ Time: 08:28:31 PM PST US From: "John Hauck" Subject: Re: Kolb-List: Thrust line change --> Kolb-List message posted by: "John Hauck" | to the horizon while in straight and level flight? | | Richard Pike Richard P/Gang: Heck, what ever is the normal angle of attack at 85mph straight and level. 3 or 4 degs?? About the same angle as a B-52 approach. ;-) john h