Original Posted By: speedbrake(at)sbcglobal.net
RE: Pietenpol-List: CG vs Wheels Location
RE: Pietenpol-List: CG vs Wheels Location
Original Posted By: speedbrake(at)sbcglobal.net
RE: Pietenpol-List: CG vs Wheels Location
Original Posted By: speedbrake(at)sbcglobal.net
Thanks=2C Michael. I have heard from others about "this is what I did." I very much appreciate the all the input from everyone. I'm still waiting for the WW Wt&Bal articles to arrive which may shed some more light on my questioning. And perhaps the curmudgeons will heap abuse on me for even considering deviating from the plans. But I'm looking for some general design guidance on how (where) to locate the gear for a taildragger. Design guidance is pretty standard for allowable CG range=2C given the Center-of-Lift of the wing (%MAC). I'm beginning to believe that locating the gear may be a matter of trial and error=2C though. You can't have the wheels too far out ahead of the CG or you will have controllability problems on landing. On the other hand=2C if you get the wheels too far back=2C close to the CG=2C you nose over at the first application of brakes. I understand that others have had just this problem.I think building to the plans will not work for me because I intend to include a wheel brake system. I'd like to hear if there is some range of design limits that I might start with. Or maybe I'll just pick a point others have tried with success & not worry about it. LorenzoDate: Fri=2C 21 Mar 2014 10:08:01 -0700
Thanks=2C Michael. I have heard from others about "this is what I did." I very much appreciate the all the input from everyone. I'm still waiting for the WW Wt&Bal articles to arrive which may shed some more light on my questioning. And perhaps the curmudgeons will heap abuse on me for even considering deviating from the plans. But I'm looking for some general design guidance on how (where) to locate the gear for a taildragger. Design guidance is pretty standard for allowable CG range=2C given the Center-of-Lift of the wing (%MAC). I'm beginning to believe that locating the gear may be a matter of trial and error=2C though. You can't have the wheels too far out ahead of the CG or you will have controllability problems on landing. On the other hand=2C if you get the wheels too far back=2C close to the CG=2C you nose over at the first application of brakes. I understand that others have had just this problem.I think building to the plans will not work for me because I intend to include a wheel brake system. I'd like to hear if there is some range of design limits that I might start with. Or maybe I'll just pick a point others have tried with success & not worry about it. LorenzoDate: Fri=2C 21 Mar 2014 10:08:01 -0700
Pietenpol-List: Re: CG vs Wheels Location
Original Posted By: "jarheadpilot82"
Larry,I am taking your comments as some type of joke, because I am not sure why elseanyone who has earned an ATP would make the kind of comment you just did."Flying Safely" isn't the kind of term that I would choose to use. Since you havean ATP, I assume that at work you use the term Risk Management, and understandthat while Pietenpols flew 80 years ago at a then acceptable level of risk,that it is perfectly OK for todays builders to look for a lower level of riskin their own plane today.In 1930's ATP's of that era flew DC-3s with flammable 5606 hydraulic fluid andextinguishers filled with Carbon Tetrachloride. Should DC-3 owners today abandonSkydrol and Halon? New guys reading this list see ATP after your name and havean expectation of valid risk management advice. Speaking out against discussingsmall, but important improvements, is not a particularly funny joke to me.I worked long and hard on the W&B project as an important risk management toolfor builders. Perhaps this should buy a little credibility. Please share whatcontribution to your fellow builders you are working towards with your comments,I like to understand.-wwRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: CG vs Wheels Location
Larry,I am taking your comments as some type of joke, because I am not sure why elseanyone who has earned an ATP would make the kind of comment you just did."Flying Safely" isn't the kind of term that I would choose to use. Since you havean ATP, I assume that at work you use the term Risk Management, and understandthat while Pietenpols flew 80 years ago at a then acceptable level of risk,that it is perfectly OK for todays builders to look for a lower level of riskin their own plane today.In 1930's ATP's of that era flew DC-3s with flammable 5606 hydraulic fluid andextinguishers filled with Carbon Tetrachloride. Should DC-3 owners today abandonSkydrol and Halon? New guys reading this list see ATP after your name and havean expectation of valid risk management advice. Speaking out against discussingsmall, but important improvements, is not a particularly funny joke to me.I worked long and hard on the W&B project as an important risk management toolfor builders. Perhaps this should buy a little credibility. Please share whatcontribution to your fellow builders you are working towards with your comments,I like to understand.-wwRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: CG vs Wheels Location
Original Posted By: jim hyde
You are wise to wait at least until you have read the W&B articles before makingany hard decisions about your gear placement. I would take the analysis andrecorded data of the articles over any empirical analysis backed up with "it hasflown for years that way". When William Wynne was working on my steel tube fuselage, one of the main concernshe had was the fact that the gear was set as it would have been in the 1930's(pre-brakes era), and the gear geometry needed to be reset in order to preventany chance of nose over on hard braking. You are wise to consider the change.Any curmudgeonly arrows thrown over an issue that you bring up (ultimatelythe safety of pilot and passenger) should be disregarded.--------Semper Fi,Terry HandAthens, GAUSMC, USMCR, ATPBVD DVD PDQ BBQRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Fri, 21 Mar 2014 16:54:57 -0700 (PDT)
You are wise to wait at least until you have read the W&B articles before makingany hard decisions about your gear placement. I would take the analysis andrecorded data of the articles over any empirical analysis backed up with "it hasflown for years that way". When William Wynne was working on my steel tube fuselage, one of the main concernshe had was the fact that the gear was set as it would have been in the 1930's(pre-brakes era), and the gear geometry needed to be reset in order to preventany chance of nose over on hard braking. You are wise to consider the change.Any curmudgeonly arrows thrown over an issue that you bring up (ultimatelythe safety of pilot and passenger) should be disregarded.--------Semper Fi,Terry HandAthens, GAUSMC, USMCR, ATPBVD DVD PDQ BBQRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Fri, 21 Mar 2014 16:54:57 -0700 (PDT)
Pietenpol-List: Re: verbosity
Original Posted By: "William Wynne"
Lorenzo,Everything that you are asking is actually covered in the articles in great depth.Where the axle and where the wing go are not a guess nor a rough estimation,they are now a calculation When building, use this set of steps: 1) Find a plane in the weight and balance data with the same fuselage length andengine you are going to use.2) Make a calculated mathematical correction to adjust for you specific plane,ie max pilot weight, etc. to make sure that your wing/fuselage relationship keepsthe CG between 15" and 20" aft of the leading edge at all loadings.3) Then, locate the axle from 0 to 3" behind the leading edge if you are usingbrakes.No Matter what anyone tells you, If you do the above, you are actually Followingthe plans. My weight and Balance work did not establish any new limits nor axlelocations. All I did was follow the data that BHP published in the 1960s.I have had it since getting it with my drawing set from Don P. in 1989. Peoplewith brakes, building with the 1930's axle location are actually not followingthe plans, nor any of the data BHP later developed and published.I have a pile of engineering books and stacks of drawing of classic aircraft. Almostevery single bit of data for planes with brakes that have high wings andtail wheels indicated they all have the axle close to the leading edge. Luscombe,Aeronca, Piper, Taylorcraft, Cessna, all of them run it forward, and so didBHP once he got brakes.------------------------------------------------------Michael Perez: Keep in mind, I say things plain when safety is in question. Yourcomments in the letter tell me you are making a mistake, and do not know it.Bluntly, no one needs to move the axle backward. I could not tell from your websitewhat engine you are using, but if is lighter than a 235 Lycoming or youweigh more than 110 pounds dressed, you are creating a plane that will have aterrible aft CG location. Consider ceasing to advise people on what is OK onCG. You may have built your gear already, but if you willfully ignore the contentof my W&B data, you will regret it. You offer a lot of DVD's for sale fora guy who is yet to fly his plane. Some people hold that God created the universe, and thus also created Physics,Chemistry and Gravity. They also hold that he is never absent, as long as theyare at work. Play by their rules, they are the best and most reliable protectionyou can get. Try to get around them, and they are merciless. These same peopleuphold that it is disrespectful to ask to be physically saved by divine interventionwhen you got in trouble by breaking the rules of the forces God created.Some people believe in luck, but can offer no evidence of it. I have seenmany airplane accidents, and every one offers complete proof of Physics Chemistryand Gravity. Some people se it as wreckage, others see it as what happenswhen people tell God they don't believe in the forces he created. Take yourpick.-------------------------------------------------If a plane needs the axle moved back to lift the tail under power, in all likelyhood, what you are seeing is a plane with a seriously aft CG. This is coveredin the W&B articles. If a plane is flying at 20" the tail will be heavier forany gear location than one flying in the middle of the range. Aft gear is aninvitation to a nose over, but the only thing that makes this rare is the sameplane having an aft CG. You don't fix one mistake with a second.The gear on my pit was at the leading edge, the plane could stay in CG with a 290#pilot, I could stand on the brakes with the Corvair at full throttle and liftthe tail with a 165# pilot. I started with an 8 degree deck angle and laterwent to 13. The plane could be 3 pointed 10 mph slower. I Often pilots who reportweak ailerons at low speed are forgetting to use enough rudder. Lookingover the nose on landing is a very poor technique. Keep in mind that my instructortrained more than 2,000 pilots between 1952 and 2008. Almost all of thiswas in tail wheels, 2,500 hours of it in Pitts's. He has 12,000 hours...of instruction.If you want to practice for your Piet, learn how to 3 point a J-3 fromthe rear seat. If your instructor wants to only teach wheel landings, he isgiving you only part of a tool set you will need all of one day. -wwRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: verbosity
Lorenzo,Everything that you are asking is actually covered in the articles in great depth.Where the axle and where the wing go are not a guess nor a rough estimation,they are now a calculation When building, use this set of steps: 1) Find a plane in the weight and balance data with the same fuselage length andengine you are going to use.2) Make a calculated mathematical correction to adjust for you specific plane,ie max pilot weight, etc. to make sure that your wing/fuselage relationship keepsthe CG between 15" and 20" aft of the leading edge at all loadings.3) Then, locate the axle from 0 to 3" behind the leading edge if you are usingbrakes.No Matter what anyone tells you, If you do the above, you are actually Followingthe plans. My weight and Balance work did not establish any new limits nor axlelocations. All I did was follow the data that BHP published in the 1960s.I have had it since getting it with my drawing set from Don P. in 1989. Peoplewith brakes, building with the 1930's axle location are actually not followingthe plans, nor any of the data BHP later developed and published.I have a pile of engineering books and stacks of drawing of classic aircraft. Almostevery single bit of data for planes with brakes that have high wings andtail wheels indicated they all have the axle close to the leading edge. Luscombe,Aeronca, Piper, Taylorcraft, Cessna, all of them run it forward, and so didBHP once he got brakes.------------------------------------------------------Michael Perez: Keep in mind, I say things plain when safety is in question. Yourcomments in the letter tell me you are making a mistake, and do not know it.Bluntly, no one needs to move the axle backward. I could not tell from your websitewhat engine you are using, but if is lighter than a 235 Lycoming or youweigh more than 110 pounds dressed, you are creating a plane that will have aterrible aft CG location. Consider ceasing to advise people on what is OK onCG. You may have built your gear already, but if you willfully ignore the contentof my W&B data, you will regret it. You offer a lot of DVD's for sale fora guy who is yet to fly his plane. Some people hold that God created the universe, and thus also created Physics,Chemistry and Gravity. They also hold that he is never absent, as long as theyare at work. Play by their rules, they are the best and most reliable protectionyou can get. Try to get around them, and they are merciless. These same peopleuphold that it is disrespectful to ask to be physically saved by divine interventionwhen you got in trouble by breaking the rules of the forces God created.Some people believe in luck, but can offer no evidence of it. I have seenmany airplane accidents, and every one offers complete proof of Physics Chemistryand Gravity. Some people se it as wreckage, others see it as what happenswhen people tell God they don't believe in the forces he created. Take yourpick.-------------------------------------------------If a plane needs the axle moved back to lift the tail under power, in all likelyhood, what you are seeing is a plane with a seriously aft CG. This is coveredin the W&B articles. If a plane is flying at 20" the tail will be heavier forany gear location than one flying in the middle of the range. Aft gear is aninvitation to a nose over, but the only thing that makes this rare is the sameplane having an aft CG. You don't fix one mistake with a second.The gear on my pit was at the leading edge, the plane could stay in CG with a 290#pilot, I could stand on the brakes with the Corvair at full throttle and liftthe tail with a 165# pilot. I started with an 8 degree deck angle and laterwent to 13. The plane could be 3 pointed 10 mph slower. I Often pilots who reportweak ailerons at low speed are forgetting to use enough rudder. Lookingover the nose on landing is a very poor technique. Keep in mind that my instructortrained more than 2,000 pilots between 1952 and 2008. Almost all of thiswas in tail wheels, 2,500 hours of it in Pitts's. He has 12,000 hours...of instruction.If you want to practice for your Piet, learn how to 3 point a J-3 fromthe rear seat. If your instructor wants to only teach wheel landings, he isgiving you only part of a tool set you will need all of one day. -wwRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: verbosity
Re: Pietenpol-List: Re: CG vs Wheels Location
Original Posted By: airlion2(at)gmail.com
Jim,Very nice resume. Sounds like you have been around planes for a long time. I have not seen that BHP ever had an engine other than a Ford or a Corvair in hispersonal Air campers, other than a single photo of one that briefly had a Villieradial. Your comment "put an airworthy AIRPLANE motor in the nose" strikes me as interesting.Are you saying BHP didn't build his own plane the right way? He bought his first Corvair engine in 1960. It cost about $500. My guess is thata used $500 A-65 in 1960 frequently could be had with a free used Cub airframebolted to it as a package deal. I think the man wanted to use a Corvair, Idon't think he was trying to save money.He built two new planes in the next decade, both with Corvairs. If someone buildsan exact replica of the "Last original", I think he is building arguably bythe last and most up to date set of plans. You can't get more original than that.-wwRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Re: Pietenpol-List: Re: CG vs Wheels Location
Jim,Very nice resume. Sounds like you have been around planes for a long time. I have not seen that BHP ever had an engine other than a Ford or a Corvair in hispersonal Air campers, other than a single photo of one that briefly had a Villieradial. Your comment "put an airworthy AIRPLANE motor in the nose" strikes me as interesting.Are you saying BHP didn't build his own plane the right way? He bought his first Corvair engine in 1960. It cost about $500. My guess is thata used $500 A-65 in 1960 frequently could be had with a free used Cub airframebolted to it as a package deal. I think the man wanted to use a Corvair, Idon't think he was trying to save money.He built two new planes in the next decade, both with Corvairs. If someone buildsan exact replica of the "Last original", I think he is building arguably bythe last and most up to date set of plans. You can't get more original than that.-wwRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Re: Pietenpol-List: Re: CG vs Wheels Location
Re: Pietenpol-List: Re: CG vs Wheels Location
Original Posted By: airlion2(at)gmail.com
Hi Terry, I know what USMC, USMCR , and ATP stand for but what does BVD, DVD, PDQand BBQ mean? Gardiner Sent from my iPad> On Mar 21, 2014, at 6:22 PM, "jarheadpilot82" wrote:> > > You are wise to wait at least until you have read the W&B articles before makingany hard decisions about your gear placement. I would take the analysis andrecorded data of the articles over any empirical analysis backed up with "ithas flown for years that way". > > When William Wynne was working on my steel tube fuselage, one of the main concernshe had was the fact that the gear was set as it would have been in the 1930's(pre-brakes era), and the gear geometry needed to be reset in order to preventany chance of nose over on hard braking. You are wise to consider the change.Any curmudgeonly arrows thrown over an issue that you bring up (ultimatelythe safety of pilot and passenger) should be disregarded.> > --------> Semper Fi,> > Terry Hand> Athens, GA> > USMC, USMCR, ATP> BVD DVD PDQ BBQ> > > > > Read this topic online here:> > http://forums.matronics.com/viewtopic.p ... 789#420789> > > > > > > > > > ________________________________________________________________________________Subject: Re: Pietenpol-List: Re: CG vs Wheels Location
Hi Terry, I know what USMC, USMCR , and ATP stand for but what does BVD, DVD, PDQand BBQ mean? Gardiner Sent from my iPad> On Mar 21, 2014, at 6:22 PM, "jarheadpilot82" wrote:> > > You are wise to wait at least until you have read the W&B articles before makingany hard decisions about your gear placement. I would take the analysis andrecorded data of the articles over any empirical analysis backed up with "ithas flown for years that way". > > When William Wynne was working on my steel tube fuselage, one of the main concernshe had was the fact that the gear was set as it would have been in the 1930's(pre-brakes era), and the gear geometry needed to be reset in order to preventany chance of nose over on hard braking. You are wise to consider the change.Any curmudgeonly arrows thrown over an issue that you bring up (ultimatelythe safety of pilot and passenger) should be disregarded.> > --------> Semper Fi,> > Terry Hand> Athens, GA> > USMC, USMCR, ATP> BVD DVD PDQ BBQ> > > > > Read this topic online here:> > http://forums.matronics.com/viewtopic.p ... 789#420789> > > > > > > > > > ________________________________________________________________________________Subject: Re: Pietenpol-List: Re: CG vs Wheels Location
Original Posted By: "Chris"
Now I think you are pulling my leg. GardinerSent from my iPad> On Mar 21, 2014, at 8:59 PM, airlion2(at)gmail.com wrote:> > Hi Terry, I know what USMC, USMCR , and ATP stand for but what does BVD, DVD,PDQ and BBQ mean? Gardiner > > > > Sent from my iPad> >> On Mar 21, 2014, at 6:22 PM, "jarheadpilot82" wrote:>> >> >> You are wise to wait at least until you have read the W&B articles before makingany hard decisions about your gear placement. I would take the analysis andrecorded data of the articles over any empirical analysis backed up with "ithas flown for years that way". >> >> When William Wynne was working on my steel tube fuselage, one of the main concernshe had was the fact that the gear was set as it would have been in the1930's (pre-brakes era), and the gear geometry needed to be reset in order toprevent any chance of nose over on hard braking. You are wise to consider thechange. Any curmudgeonly arrows thrown over an issue that you bring up (ultimatelythe safety of pilot and passenger) should be disregarded.>> >> -------->> Semper Fi,>> >> Terry Hand>> Athens, GA>> >> USMC, USMCR, ATP>> BVD DVD PDQ BBQ>> >> >> >> >> Read this topic online here:>> >> http://forums.matronics.com/viewtopic.p ... 789#420789>> >> >> >> >> >> >> >> >> >> ________________________________________________________________________________
Now I think you are pulling my leg. GardinerSent from my iPad> On Mar 21, 2014, at 8:59 PM, airlion2(at)gmail.com wrote:> > Hi Terry, I know what USMC, USMCR , and ATP stand for but what does BVD, DVD,PDQ and BBQ mean? Gardiner > > > > Sent from my iPad> >> On Mar 21, 2014, at 6:22 PM, "jarheadpilot82" wrote:>> >> >> You are wise to wait at least until you have read the W&B articles before makingany hard decisions about your gear placement. I would take the analysis andrecorded data of the articles over any empirical analysis backed up with "ithas flown for years that way". >> >> When William Wynne was working on my steel tube fuselage, one of the main concernshe had was the fact that the gear was set as it would have been in the1930's (pre-brakes era), and the gear geometry needed to be reset in order toprevent any chance of nose over on hard braking. You are wise to consider thechange. Any curmudgeonly arrows thrown over an issue that you bring up (ultimatelythe safety of pilot and passenger) should be disregarded.>> >> -------->> Semper Fi,>> >> Terry Hand>> Athens, GA>> >> USMC, USMCR, ATP>> BVD DVD PDQ BBQ>> >> >> >> >> Read this topic online here:>> >> http://forums.matronics.com/viewtopic.p ... 789#420789>> >> >> >> >> >> >> >> >> >> ________________________________________________________________________________
RE: Pietenpol-List: CG vs Wheels Location
Original Posted By: owner-pietenpol-list-server(at)matronics.com
The excellent article by Ryan Mueller and William Wynne published in theJanuary 2013 newsletter referenced the correct landing gear placementsaying, "The late model plans specify that the axle should only be 0.5"behind the leading edge"(fourth paragraph of the article). This is not onthe plans. It is found on an 8.5x11 piece of paper I received with my plansset. This sheet shows the weight and balance computations for a "1966Pietenpol Air Camper Powered with a 110-66 Corvair Engine". On this it says"D is 0.5 inches back of weighing point" and D is the distance from the mainwheel to the datum (leading edge). The fuselage measurement and vintagesuggest this is a long fuselage.Also, when I received my plans, I received a 6 page document entitled"Converting the Corvair Engine" by Mr. Pietenpol. On page 1 Mr. Pietenpollists the empty weight of this airplane using the modified Corvair engine at622 pounds, which happens to be the same weight as the one on the weight andbalance sheet mentioned above. On page two Mr. Pietenpol list themodifications to this plane. The important ones for this discussion are:-fuselage lengthened 9 inches (the genesis of the LONG fuselage) -wings slanted back 3 inches-wheels moved forward 7 inches so that a modified J3 Cub landing gear andbrakes could be fitted.Using a little math, if the split axel landing gear legs were built per theplans the axel would be 19 inches from the long fuselage firewall (17 inchesfor the standard plans fuselage plus 2 inches more for the LONG fuselageextension of the first bay). Then moving the axel forward 7 inches wouldput it at 19-7= 12 inches back from the firewall. The wing was at 7.5inches on the standard fuselage plus 2 inches (extension of the first bay)puts the wing at 9.5 inches behind the firewall plus the 3 inch slant putsthe wing at 12.5 inches from the firewall. This brings us back to the 0.5inch measurement but in this case its axel in front of the wing. I'mguessing the J# gear had a slightly different sweep to the gear legs. Thismodified airplane Mr. Pietenpol speaks of must be the same as the "1966Pietenpol Air Camper Powered with a 110-66 Corvair Engine" airplane shown onthe weight and balance sheet. However, Mr. Pietenpol goes on to say on page2 that 7 inches was too much. He recommends splitting the difference whichwould mean the axel should be at 12+3.5=15.5 inches behind the firewall or 3inches behind the leading edge of this aircrafts wing. Remember he istalking about a long fuselage. Note that this location is behind thisparticular plane's leading edge. The important factor in the location ofthe axel that is not mentioned is the CG. If you make sure you operatingwithin the recommended CG envelope I believe the advice would be that youraxel placement should not be any farther back than the 3 inches behind theleading edge that Mr. Pietenpol recommends. Background research on landing gear placement shows:-The 1933-34 "Improved Air Camper" plans, no brakes: show the axel to be 17inches behind the firewall and the wing 7.5 inches behind the firewall. Thisputs the axel 9.5 inches behind the wings leading edge.-The LONG fuselage adds 2 inches to the first bay so if using the landinggear form the 1933-34 plans it should be at 19 inches behind the firewalland the wing should be at 7.5+2 or 9.5 inches from the firewall. - In the plans: the fuselage drawing with the sample weight and balanceshown on the supplemental plan sheet (also showing the tube fuselage)appears to be a 1933-34 plans fuselage but with brakes. Here the axle isshown at 16.5 inches behind the firewall and 5.25 inches behind the leadingedge of the wing.-There is no advice for the axel placement on the supplemental plans for theLONG fuselage without brakes. However Chris Bobka did some research andguesswork to figure it should be at 21 inches behind the firewall with nobrakes. He did the analysis to help Greg and Dale with their LONG fuselagePietenpol. Chris reported during flight tests that the placement was righton. I believe Gary Boothe has his long fuselage axel located per the split axelplans. Wing back 4 inches. (Correct me if I am wrong Garry) And it seems tobehave fine.- The 4th Quarter 1984 Brodhead Pietenpol newsletter they quote Mr.Pietenpol as saying, the plane is OK with the gear as far forward as it isnow, with a note saying he was talking about the last two Corvair poweredships. But unfortunately it does not say where the axel is. Looking at modern high wing planes with tail wheel seem to show main wheelat about the leading edge of the wing.Lastly, in an article about landing gear design published in Sport Aviationby Ladislao Pazmany, he states "The main gear should contact the ground atleast 15 degrees ahead of the most forward center of gravity with theaircraft in level attitude." This center of gravity is the CG of the planeand on a parasol plane it is somewhere below the wing. Unfortunately, Idon't know where this point is on a Pietenpol. Some have suggested it isabout the center of the instrument panel but that is just a guess. As anaside I also found in "Aeronautical Engineering and Airplane Design"published in 1918, the landing gear should be at 13 degrees 10 minutes. Italso assumes the CG is the same height as the propeller.Chris T.Sacramento, CaWestcoastpiet.com
The excellent article by Ryan Mueller and William Wynne published in theJanuary 2013 newsletter referenced the correct landing gear placementsaying, "The late model plans specify that the axle should only be 0.5"behind the leading edge"(fourth paragraph of the article). This is not onthe plans. It is found on an 8.5x11 piece of paper I received with my plansset. This sheet shows the weight and balance computations for a "1966Pietenpol Air Camper Powered with a 110-66 Corvair Engine". On this it says"D is 0.5 inches back of weighing point" and D is the distance from the mainwheel to the datum (leading edge). The fuselage measurement and vintagesuggest this is a long fuselage.Also, when I received my plans, I received a 6 page document entitled"Converting the Corvair Engine" by Mr. Pietenpol. On page 1 Mr. Pietenpollists the empty weight of this airplane using the modified Corvair engine at622 pounds, which happens to be the same weight as the one on the weight andbalance sheet mentioned above. On page two Mr. Pietenpol list themodifications to this plane. The important ones for this discussion are:-fuselage lengthened 9 inches (the genesis of the LONG fuselage) -wings slanted back 3 inches-wheels moved forward 7 inches so that a modified J3 Cub landing gear andbrakes could be fitted.Using a little math, if the split axel landing gear legs were built per theplans the axel would be 19 inches from the long fuselage firewall (17 inchesfor the standard plans fuselage plus 2 inches more for the LONG fuselageextension of the first bay). Then moving the axel forward 7 inches wouldput it at 19-7= 12 inches back from the firewall. The wing was at 7.5inches on the standard fuselage plus 2 inches (extension of the first bay)puts the wing at 9.5 inches behind the firewall plus the 3 inch slant putsthe wing at 12.5 inches from the firewall. This brings us back to the 0.5inch measurement but in this case its axel in front of the wing. I'mguessing the J# gear had a slightly different sweep to the gear legs. Thismodified airplane Mr. Pietenpol speaks of must be the same as the "1966Pietenpol Air Camper Powered with a 110-66 Corvair Engine" airplane shown onthe weight and balance sheet. However, Mr. Pietenpol goes on to say on page2 that 7 inches was too much. He recommends splitting the difference whichwould mean the axel should be at 12+3.5=15.5 inches behind the firewall or 3inches behind the leading edge of this aircrafts wing. Remember he istalking about a long fuselage. Note that this location is behind thisparticular plane's leading edge. The important factor in the location ofthe axel that is not mentioned is the CG. If you make sure you operatingwithin the recommended CG envelope I believe the advice would be that youraxel placement should not be any farther back than the 3 inches behind theleading edge that Mr. Pietenpol recommends. Background research on landing gear placement shows:-The 1933-34 "Improved Air Camper" plans, no brakes: show the axel to be 17inches behind the firewall and the wing 7.5 inches behind the firewall. Thisputs the axel 9.5 inches behind the wings leading edge.-The LONG fuselage adds 2 inches to the first bay so if using the landinggear form the 1933-34 plans it should be at 19 inches behind the firewalland the wing should be at 7.5+2 or 9.5 inches from the firewall. - In the plans: the fuselage drawing with the sample weight and balanceshown on the supplemental plan sheet (also showing the tube fuselage)appears to be a 1933-34 plans fuselage but with brakes. Here the axle isshown at 16.5 inches behind the firewall and 5.25 inches behind the leadingedge of the wing.-There is no advice for the axel placement on the supplemental plans for theLONG fuselage without brakes. However Chris Bobka did some research andguesswork to figure it should be at 21 inches behind the firewall with nobrakes. He did the analysis to help Greg and Dale with their LONG fuselagePietenpol. Chris reported during flight tests that the placement was righton. I believe Gary Boothe has his long fuselage axel located per the split axelplans. Wing back 4 inches. (Correct me if I am wrong Garry) And it seems tobehave fine.- The 4th Quarter 1984 Brodhead Pietenpol newsletter they quote Mr.Pietenpol as saying, the plane is OK with the gear as far forward as it isnow, with a note saying he was talking about the last two Corvair poweredships. But unfortunately it does not say where the axel is. Looking at modern high wing planes with tail wheel seem to show main wheelat about the leading edge of the wing.Lastly, in an article about landing gear design published in Sport Aviationby Ladislao Pazmany, he states "The main gear should contact the ground atleast 15 degrees ahead of the most forward center of gravity with theaircraft in level attitude." This center of gravity is the CG of the planeand on a parasol plane it is somewhere below the wing. Unfortunately, Idon't know where this point is on a Pietenpol. Some have suggested it isabout the center of the instrument panel but that is just a guess. As anaside I also found in "Aeronautical Engineering and Airplane Design"published in 1918, the landing gear should be at 13 degrees 10 minutes. Italso assumes the CG is the same height as the propeller.Chris T.Sacramento, CaWestcoastpiet.com
Pietenpol-List: Re: CG vs Wheels Location
Original Posted By: "Don Emch"
WW=2C I very much appreciate your input. I eagerly await the arrival of the articles you authored. You are correct that proper CG location is critical to good controllability in the finished airplane. That's why I have been such a pest on the issue. I suspect that you are also right in that many finished=2C and unused=2C planes are that way because they scare their owners.I value the DVDs that Michael Perez has put together. I have my set of plans to use for dimensions=2C etc. And my own standards for workmanship. But Michael's videos show his perspective on work sequence=2C materials techniques=2C and quality of workmanship. I don't do everything the same as he does=2C but=2C lacking a local group to 'show-and-tell' with=2C it is nice to see how someone else has approached construction of certain components.Quote from someone else: There are Rules and there are Laws. Rules can be broken=2C Laws (of physics) cannot. ie. The Rule says that you cannot fly under the bridge. If you do fly under the bridge just be sure that you don't run into it. "If you want to practice for your Piet=2C learn how to 3 point a J-3 from the rear seat." How about a no-flap from the back seat of a T-38? If that counts=2C I'm good to go. :)Lorenzo> > ============================================> > > ________________________________________________________________________________Subject: Pietenpol-List: Re: CG vs Wheels Location
WW=2C I very much appreciate your input. I eagerly await the arrival of the articles you authored. You are correct that proper CG location is critical to good controllability in the finished airplane. That's why I have been such a pest on the issue. I suspect that you are also right in that many finished=2C and unused=2C planes are that way because they scare their owners.I value the DVDs that Michael Perez has put together. I have my set of plans to use for dimensions=2C etc. And my own standards for workmanship. But Michael's videos show his perspective on work sequence=2C materials techniques=2C and quality of workmanship. I don't do everything the same as he does=2C but=2C lacking a local group to 'show-and-tell' with=2C it is nice to see how someone else has approached construction of certain components.Quote from someone else: There are Rules and there are Laws. Rules can be broken=2C Laws (of physics) cannot. ie. The Rule says that you cannot fly under the bridge. If you do fly under the bridge just be sure that you don't run into it. "If you want to practice for your Piet=2C learn how to 3 point a J-3 from the rear seat." How about a no-flap from the back seat of a T-38? If that counts=2C I'm good to go. :)Lorenzo> > ============================================> > > ________________________________________________________________________________Subject: Pietenpol-List: Re: CG vs Wheels Location
Pietenpol-List: Re: CG vs Wheels Location
Original Posted By: "William Wynne"
Good grief! Please don't over complicate this! Either build the plane withoutbrakes and keep the gear as is or add brakes and move the axle an inch or twoforward. It's really that simple!! Now go get your hack saw and light up yourtorch!Don EmchNX899DERead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: CG vs Wheels Location
Good grief! Please don't over complicate this! Either build the plane withoutbrakes and keep the gear as is or add brakes and move the axle an inch or twoforward. It's really that simple!! Now go get your hack saw and light up yourtorch!Don EmchNX899DERead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: CG vs Wheels Location
Original Posted By: "Gary Boothe"
Don,While Chris does have a long paragraph there, it is some really good research,When we wrote the series, I made note of assistance from a very well researchedbuilder. For the record, it was Chris. His notes here are all numbers, not oldstories, thus are useful in the big picture. No builder needs to know all ofthem, they just need one path that suits their plane. It isn't that complicated.If it takes 1,000 trips to the shop to build your plane, devoting maybe one ofthem to making a good CG plan makes sense to me. BTW, I think just moving theaxle an inch or two is 4" short of BHP's recommendation.Chris, I did a W&B on the last Original in 2007. The axle is near the leading edge.The only 'cub' parts to the gear are the wheels, axle size, and tires. Iam pretty sure it does not have brakes. I would like to do it and the plane atPioneer (the 1966) again this year. I think they are physical examples of howBHP thought the design was 'optimal.' -wwRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________
Don,While Chris does have a long paragraph there, it is some really good research,When we wrote the series, I made note of assistance from a very well researchedbuilder. For the record, it was Chris. His notes here are all numbers, not oldstories, thus are useful in the big picture. No builder needs to know all ofthem, they just need one path that suits their plane. It isn't that complicated.If it takes 1,000 trips to the shop to build your plane, devoting maybe one ofthem to making a good CG plan makes sense to me. BTW, I think just moving theaxle an inch or two is 4" short of BHP's recommendation.Chris, I did a W&B on the last Original in 2007. The axle is near the leading edge.The only 'cub' parts to the gear are the wheels, axle size, and tires. Iam pretty sure it does not have brakes. I would like to do it and the plane atPioneer (the 1966) again this year. I think they are physical examples of howBHP thought the design was 'optimal.' -wwRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________
RE: Pietenpol-List: CG vs Wheels Location
Original Posted By: owner-pietenpol-list-server(at)matronics.com
".I believe Gary Boothe has his long fuselage axel located per the splitaxel plans. Wing back 4 inches. (Correct me if I am wrong Gary) And it seemsto behave fine.."You're correct. Plane behaves fine.It's me who behaves badly.Gary BootheNX308MB
".I believe Gary Boothe has his long fuselage axel located per the splitaxel plans. Wing back 4 inches. (Correct me if I am wrong Gary) And it seemsto behave fine.."You're correct. Plane behaves fine.It's me who behaves badly.Gary BootheNX308MB
Re: Pietenpol-List: Re: CG vs Wheels Location
Original Posted By: Ryan Mueller
Timed the fuel flow in the 3-point attitude today. Filled a quart container in21 seconds, so it's not fuel flow.Adjusted the damper blade in the air box to shut tightly when carb heat is off,then warmed up the engine and ran it up. It still will not take throttle above1500 RPM without carb heat on, and will not run up to full static power withoutit. So it's not the carb heat box.I'm thinking more and more that it's an obstructed passageway or something in thecarb. I'm rebuilding a core Stromberg and when it's ready, I'll swap it outwith the one that's on the engine and we'll see if that's it. Meanwhile, I'mencouraged that the engine starts very readily and idles well. As soon as it'srunning right, it will be ready for annual.--------Oscar ZunigaMedford, ORAir Camper NX41CC "Scout"A75 powerRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Sat, 22 Mar 2014 21:24:27 -0500Subject: Re: Pietenpol-List: Re: CG vs Wheels Location
Timed the fuel flow in the 3-point attitude today. Filled a quart container in21 seconds, so it's not fuel flow.Adjusted the damper blade in the air box to shut tightly when carb heat is off,then warmed up the engine and ran it up. It still will not take throttle above1500 RPM without carb heat on, and will not run up to full static power withoutit. So it's not the carb heat box.I'm thinking more and more that it's an obstructed passageway or something in thecarb. I'm rebuilding a core Stromberg and when it's ready, I'll swap it outwith the one that's on the engine and we'll see if that's it. Meanwhile, I'mencouraged that the engine starts very readily and idles well. As soon as it'srunning right, it will be ready for annual.--------Oscar ZunigaMedford, ORAir Camper NX41CC "Scout"A75 powerRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Sat, 22 Mar 2014 21:24:27 -0500Subject: Re: Pietenpol-List: Re: CG vs Wheels Location
Re: Pietenpol-List: Re: CG vs Wheels Location
Original Posted By: Ryan Mueller
Hey Gardiner,You could add washers one by one to the jig until your mount tubes arecorrectly spaced, or close. Then tack the thing together and remove it fromthe jig. Bolt it onto the firewall and if you have to move some thingsaround a bit, just cut the tacks. Once it's bolted on, re-tack and add lotsof small tacks everywhere so it can't warp. You should then be able tofinish the welds away from the firewall easily. you could then conceivablycover up the planes front-end with a welding blanket if you are tigging anddo a lot of the welds at that end of the mount. Or just make put lots oftacks so it can't shift around and finish them off the plane.If you're gas welding, you'll have to obviously be more careful about theplane, but a welding tarp should protect it.If you have a nose tank, or there's any fuel anywhere around, you shouldn'ttry this technique.Douwe________________________________________________________________________________Date: Sun, 23 Mar 2014 10:35:44 -0500Subject: Re: Pietenpol-List: Re: CG vs Wheels Location
Hey Gardiner,You could add washers one by one to the jig until your mount tubes arecorrectly spaced, or close. Then tack the thing together and remove it fromthe jig. Bolt it onto the firewall and if you have to move some thingsaround a bit, just cut the tacks. Once it's bolted on, re-tack and add lotsof small tacks everywhere so it can't warp. You should then be able tofinish the welds away from the firewall easily. you could then conceivablycover up the planes front-end with a welding blanket if you are tigging anddo a lot of the welds at that end of the mount. Or just make put lots oftacks so it can't shift around and finish them off the plane.If you're gas welding, you'll have to obviously be more careful about theplane, but a welding tarp should protect it.If you have a nose tank, or there's any fuel anywhere around, you shouldn'ttry this technique.Douwe________________________________________________________________________________Date: Sun, 23 Mar 2014 10:35:44 -0500Subject: Re: Pietenpol-List: Re: CG vs Wheels Location