Pietenpol-List: Pietenpol weight and balance (http://members.aol.com/gmaclaren/wb
Posted: Tue Sep 07, 1999 8:41 am
Original Posted By: fishin
This page from the BPA newsletter may be of some interest to ourmembers.Mike B Piet N687MB ( Mr Sam ) The results are in . . .byJack Broomall22200 Heatheridge LaneNorthville, MI 48167andDon Verdiani103 Lockerbie LaneWest Chester, PA 19382Those of you who were fortunate enough to attend Brodhead '94 may knowthat we were able to measure weight and center of gravity informationfor eight of the aircraft attending the event.The reason for undertaking this exercise was to provide a bank ofinformation that Piet builders could refer to and use in configuringtheir aircraft. Over the past several years we have noticed that thereare a variety of types of Air Campers flying with different engines, atleast two common fuselage lengths, different wing positions, anddifferent flying characteristics (if you doubt this take a close look atthe various aircraft taking off and landing at Brodhead!). Collectingthe weight and balance information on a number of flying aircraft seemedlike a good way to gain some insight in this area.The data table (below) summarizes the most important information whichwas accumulated.We were fortunate to be able to inspect examples of each of the threemost common powerplants (Ford, Corvair, and Continental).In the third column we categorize the fuselage as 'short' (the originaldesign) or long (the so-called 'improved' air camper).In column 4 we show the aircraft's empty weight. In each case theaircraft was presented for weighing with some amount of fuel on board.We asked each owner to estimate how much fuel was in the aircraft, andthen corrected to an empty weight using that estimate and the standardvalue of 6 lbs. per gallon for gasoline.While there is some degree of 'estimating' in these numbers, we arecomfortable that they are reasonably accurate.In the fifth column, we show the empty aircraft's center of gravitylocation with respect to the wing leading edge. We chose the wingleading edge as a datum because it was the best way to normalize thedata to a large variety of aircraft and also because that's what Mr.Pietenpol used!For comparative purposes there is a published weight and balancesummary, done in 1965, showing a Corvair powered Air Camper with anempty C.G. 8.71 inches aft of datum. Very few of us fly airplanes empty,with no passengers! Fortunatly, using the data we collected, we are ableto calculate center of gravity location for any loading condition.In the sixth column, we show the calculated C.G. location when theaircraft was loaded with an FAA standard 170 pound pilot in the backseat, and 7 gallons of fuel in the 'main' fuel tank. This mightrepresent a 'typical' loading for pilot only. Since we weighed someaircraft with both wing tanks and fueslage tanks we elected to(mathematically) put the 7 gallons of fuel in whichever tank was bigger.Again a comparison is available.The previously mentioned weight and balance chart included a C.G.calculation for that aircraft with 7 gallons of fuel and a 166 poundpilot on board (Did BHP weigh 166 pounds?). His example aircraft has aC.G. 9.51" aft of datum in that loading condition.As a final set of calculations we've shown aircraft weight and C.G.location when each aircraft is loaded with a 170 pilot, a 170 poundpassenger, and it's fuel tank(s) full. These weights are shown in columnG and the C.G. location is in column H. We found these weightsinteresting in that some of the aircraft have surprisingly high grossweights. Also, there are several aircraft which, in one loadingcondition or another, seem to violate BHP's recommendation to neverexceed 20" aft of datum C.G. (also shown in the 1965 weight and balancesheet).Because of the conditions under which all of our information wascollected and because there was no chance to double check anymeasurements there is some real chance that there may be errors in ouranalysis. However, there is enough consistency in the data to feelfairly confident about it's accuracy.We would like to thank all the fine folks at Brodhead for helping uswith this project. And special thanks are due to the eight aircraftowners who donated their aircraft as well as their time and help. We'dlike to think this activity has produced information of real value tothe community of Pietenpol builders and pilots! Anyone who has anyquestions can feel free to contact either of us at the addresses above.Pietenpol Weight & Balance ________________________________________________________________________________
This page from the BPA newsletter may be of some interest to ourmembers.Mike B Piet N687MB ( Mr Sam ) The results are in . . .byJack Broomall22200 Heatheridge LaneNorthville, MI 48167andDon Verdiani103 Lockerbie LaneWest Chester, PA 19382Those of you who were fortunate enough to attend Brodhead '94 may knowthat we were able to measure weight and center of gravity informationfor eight of the aircraft attending the event.The reason for undertaking this exercise was to provide a bank ofinformation that Piet builders could refer to and use in configuringtheir aircraft. Over the past several years we have noticed that thereare a variety of types of Air Campers flying with different engines, atleast two common fuselage lengths, different wing positions, anddifferent flying characteristics (if you doubt this take a close look atthe various aircraft taking off and landing at Brodhead!). Collectingthe weight and balance information on a number of flying aircraft seemedlike a good way to gain some insight in this area.The data table (below) summarizes the most important information whichwas accumulated.We were fortunate to be able to inspect examples of each of the threemost common powerplants (Ford, Corvair, and Continental).In the third column we categorize the fuselage as 'short' (the originaldesign) or long (the so-called 'improved' air camper).In column 4 we show the aircraft's empty weight. In each case theaircraft was presented for weighing with some amount of fuel on board.We asked each owner to estimate how much fuel was in the aircraft, andthen corrected to an empty weight using that estimate and the standardvalue of 6 lbs. per gallon for gasoline.While there is some degree of 'estimating' in these numbers, we arecomfortable that they are reasonably accurate.In the fifth column, we show the empty aircraft's center of gravitylocation with respect to the wing leading edge. We chose the wingleading edge as a datum because it was the best way to normalize thedata to a large variety of aircraft and also because that's what Mr.Pietenpol used!For comparative purposes there is a published weight and balancesummary, done in 1965, showing a Corvair powered Air Camper with anempty C.G. 8.71 inches aft of datum. Very few of us fly airplanes empty,with no passengers! Fortunatly, using the data we collected, we are ableto calculate center of gravity location for any loading condition.In the sixth column, we show the calculated C.G. location when theaircraft was loaded with an FAA standard 170 pound pilot in the backseat, and 7 gallons of fuel in the 'main' fuel tank. This mightrepresent a 'typical' loading for pilot only. Since we weighed someaircraft with both wing tanks and fueslage tanks we elected to(mathematically) put the 7 gallons of fuel in whichever tank was bigger.Again a comparison is available.The previously mentioned weight and balance chart included a C.G.calculation for that aircraft with 7 gallons of fuel and a 166 poundpilot on board (Did BHP weigh 166 pounds?). His example aircraft has aC.G. 9.51" aft of datum in that loading condition.As a final set of calculations we've shown aircraft weight and C.G.location when each aircraft is loaded with a 170 pilot, a 170 poundpassenger, and it's fuel tank(s) full. These weights are shown in columnG and the C.G. location is in column H. We found these weightsinteresting in that some of the aircraft have surprisingly high grossweights. Also, there are several aircraft which, in one loadingcondition or another, seem to violate BHP's recommendation to neverexceed 20" aft of datum C.G. (also shown in the 1965 weight and balancesheet).Because of the conditions under which all of our information wascollected and because there was no chance to double check anymeasurements there is some real chance that there may be errors in ouranalysis. However, there is enough consistency in the data to feelfairly confident about it's accuracy.We would like to thank all the fine folks at Brodhead for helping uswith this project. And special thanks are due to the eight aircraftowners who donated their aircraft as well as their time and help. We'dlike to think this activity has produced information of real value tothe community of Pietenpol builders and pilots! Anyone who has anyquestions can feel free to contact either of us at the addresses above.Pietenpol Weight & Balance ________________________________________________________________________________