Original Posted By: "John Dilatush"
Can any of you Pieters tell me the fore and aft limits of CG, expressed aspercent of chord, for the Piet? I ask for percent of chord due to therelocatable wing on the aircraft, and therefore lack of a fixed referencepoint for the LE.Our EAA chapter (203) has received a Piet as a donation. It is a heavybird, with (almost) empty weight of 740 with a Cont. 65. It has flown offit's 25 hour test period, but the pilot complained about rear CG and lack ofclimb. Our chapter secretary had the prop re-pitched to give it betterclimb, but I do not know the current pitch.Appreciate any assistanceCraig________________________________________________________________________________
Pietenpol-List: CG limits
Re: Pietenpol-List: CG limits
Original Posted By: "Jeffrey Wilcox"
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Pietenpol-List: CG limits
Original Posted By: Steven Schaefer
Re: Pietenpol-List: Elev and rudder hinge fittings
Original Posted By: del magsam
Subject: Re: Pietenpol-List: Elev and rudder hinge fittingsIn a message dated 5/3/02 7:53:07 AM Pacific Daylight Time, srs1(at)techline.com writes:> Does anyone out there know how I can contact Vi Kapler to purchase His> elev/rudder hinge fittings? Thanks.> Steve in Wa> > > Steve,Call him at (507) 288-3322Doug Bryant________________________________________________________________________________Date: Fri, 3 May 2002 15:16:32 -0700 (PDT)
Subject: Re: Pietenpol-List: Elev and rudder hinge fittingsIn a message dated 5/3/02 7:53:07 AM Pacific Daylight Time, srs1(at)techline.com writes:> Does anyone out there know how I can contact Vi Kapler to purchase His> elev/rudder hinge fittings? Thanks.> Steve in Wa> > > Steve,Call him at (507) 288-3322Doug Bryant________________________________________________________________________________Date: Fri, 3 May 2002 15:16:32 -0700 (PDT)
Pietenpol-List: CG limits
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Corky,My sources say you will need a placard that says "solo from rear seat only"I agree that someone with a flying piet should furnish you a CG range thatthey were certified with. The actual empty CG and loaded CG won't go toofar out of line from all the other ships. It is the RANGE of allowable CGthat is key.I have spent the evening belching up the dinner and researching CG range. Ifound a good article in EAA Aircraft Design File 3 Volume 3 by L. D.Sunderland EAA 5477 on page 17. His intro reads more or less:"An important part of the design of an aircraft is the establishment of CGlimits. This is a critical design problem which should be solved through astability and control analysis. (this means tons of math). A second a lessdependable method is to copy the limits of an existing airplane and hopethat flight tests prove the selection is correct."It goes on to say that "most homebuilders will never perform such astability and control analysis" and therefore use the less desireable triedand true method of test flying.To really get into it, the aft limit is set a point just forward of thepoint where the nose will not drop down when raised and the stick is heldthere. It is when you can't provide the control inputs to get the nose downto keep from stalling. You would basically pancake to the ground. If theCG was way forward, it would always take much forceable input to move thenose up or down. This force decreases as the CG is moved aft until theforce becomes zero ie a limp dick I mean stick. It is obvious that you donot want an aft limit this far aft.The forward limit is set at the point where you have enough elevator to landthe plane with a windmilling engine. If you can't three point her with thestick at the aft stop, then the CG is too far forward. This is figured whilein ground effect because the downwash from the wing over the elevator isaffected by the ground. A 5 degree of elevator throw margin is desired hereso that you should be able to three point the ship at the forward CG limitwhile using 5 degrees less than full throw of back stick. Also, theforward limit is set by a thing called "stick force per G". This is not tobe worried about because the landing elevator required requirement is morerestrictive most of the time.The article finishes with the advice that:"The safest practice for conventional designs is to locate the CG for theinitial test flight as near the 25% chord point as possible. Then bygradually and systematically moving the CG with sandbags, determine the rearlimit where the ship will fly hands off and the forward limit which willpermit good landings. If your loading requirements demand limits which donot fall inside those determined by flight tests, you will need to makedesign modifications like adding ballast (or shifting the wing as is oftendone on the piet) or placing added restrictions on loading."I will now do the math with a higher gross wieght and send it in a fewminutes.Chris-----Original Message-----
Corky,My sources say you will need a placard that says "solo from rear seat only"I agree that someone with a flying piet should furnish you a CG range thatthey were certified with. The actual empty CG and loaded CG won't go toofar out of line from all the other ships. It is the RANGE of allowable CGthat is key.I have spent the evening belching up the dinner and researching CG range. Ifound a good article in EAA Aircraft Design File 3 Volume 3 by L. D.Sunderland EAA 5477 on page 17. His intro reads more or less:"An important part of the design of an aircraft is the establishment of CGlimits. This is a critical design problem which should be solved through astability and control analysis. (this means tons of math). A second a lessdependable method is to copy the limits of an existing airplane and hopethat flight tests prove the selection is correct."It goes on to say that "most homebuilders will never perform such astability and control analysis" and therefore use the less desireable triedand true method of test flying.To really get into it, the aft limit is set a point just forward of thepoint where the nose will not drop down when raised and the stick is heldthere. It is when you can't provide the control inputs to get the nose downto keep from stalling. You would basically pancake to the ground. If theCG was way forward, it would always take much forceable input to move thenose up or down. This force decreases as the CG is moved aft until theforce becomes zero ie a limp dick I mean stick. It is obvious that you donot want an aft limit this far aft.The forward limit is set at the point where you have enough elevator to landthe plane with a windmilling engine. If you can't three point her with thestick at the aft stop, then the CG is too far forward. This is figured whilein ground effect because the downwash from the wing over the elevator isaffected by the ground. A 5 degree of elevator throw margin is desired hereso that you should be able to three point the ship at the forward CG limitwhile using 5 degrees less than full throw of back stick. Also, theforward limit is set by a thing called "stick force per G". This is not tobe worried about because the landing elevator required requirement is morerestrictive most of the time.The article finishes with the advice that:"The safest practice for conventional designs is to locate the CG for theinitial test flight as near the 25% chord point as possible. Then bygradually and systematically moving the CG with sandbags, determine the rearlimit where the ship will fly hands off and the forward limit which willpermit good landings. If your loading requirements demand limits which donot fall inside those determined by flight tests, you will need to makedesign modifications like adding ballast (or shifting the wing as is oftendone on the piet) or placing added restrictions on loading."I will now do the math with a higher gross wieght and send it in a fewminutes.Chris-----Original Message-----