Re: Pietenpol-List: Pietenpol lift struts and center section geometry...and
Posted: Thu Mar 14, 2002 10:39 pm
Original Posted By: "Graham Hansen"
"Dennis the Menace" and others,Originally, my Piet had an empty weight of 645 lbs. with aContinental A 65 - 8 engine, a wooden propeller, Grade A cotton cover with a hand-rubbed doped finish, a Scott 6" tail-wheel, cowling of 0.032" aluminum (NO FIBREGLAS), no upholstery (just a couple of lightweight seat cushions), ASI, altimeter, tachometer, ball slip-skid indicator, oil pressure gauge and oil temperature gauge.Some 14 years later, the cotton fabric strength had diminshedmarkedly (as cotton was prone to do) and I wanted to checkthe structure, so it was stripped and gone over thoroughly with the intention of removing even more weight, if possible.A C85 - 8 engine was installed which added a few pounds over the C65 - 8 and the only places I could save weight werein the fabric cover and the tailwheel. Polyester fabric was sub-stituted for the Grade A cotton and a minimum of dope was used to provide a "serviceable" light plane finish (the originalwas similar to the finish applied to the old Beechcraft Stagger-wing biplanes!). A very light 3" caster wheel with its forks and horn made from 1/8" 4130 steel, welded together, took the placeof the heavy Scott assembly. (BHP used a similar small, light tailwheel on his last airplanes which was non-steerable---andthis inspired me, although mine is steerable via 3/32" cablesfrom the rudder pedals.)Afterward, we weighed it and the dry empty weight was 630 lbs.Since then, I have had custom seat and back cushions made,but they are extremely light in weight. I would guess about 4 Lbs.I believe I could save even more weight by using, say, 2.6 oz. fabric with a fine weave. The polyester fabric I used is too heavyat about 3.6 oz. and has a relatively coarse weave, requiringmore dope. It is so strong that I likely would never have to replaceit due to strength loss, but after over 17 years since recover I would like to check the structure. Grade A cotton used to be the standard for aircraft fabric, but was heavier than the syntheticsand deteriorated much more quickly.If I were to build another Pietenpol, I could save even more weight,but I doubt I could beat Brian Kenney's CF-AUK which has an EWsignificantly under 600 lbs.!Graham Hansen (Pietenpol CF-AUN)Alberta, Canada________________________________________________________________________________
"Dennis the Menace" and others,Originally, my Piet had an empty weight of 645 lbs. with aContinental A 65 - 8 engine, a wooden propeller, Grade A cotton cover with a hand-rubbed doped finish, a Scott 6" tail-wheel, cowling of 0.032" aluminum (NO FIBREGLAS), no upholstery (just a couple of lightweight seat cushions), ASI, altimeter, tachometer, ball slip-skid indicator, oil pressure gauge and oil temperature gauge.Some 14 years later, the cotton fabric strength had diminshedmarkedly (as cotton was prone to do) and I wanted to checkthe structure, so it was stripped and gone over thoroughly with the intention of removing even more weight, if possible.A C85 - 8 engine was installed which added a few pounds over the C65 - 8 and the only places I could save weight werein the fabric cover and the tailwheel. Polyester fabric was sub-stituted for the Grade A cotton and a minimum of dope was used to provide a "serviceable" light plane finish (the originalwas similar to the finish applied to the old Beechcraft Stagger-wing biplanes!). A very light 3" caster wheel with its forks and horn made from 1/8" 4130 steel, welded together, took the placeof the heavy Scott assembly. (BHP used a similar small, light tailwheel on his last airplanes which was non-steerable---andthis inspired me, although mine is steerable via 3/32" cablesfrom the rudder pedals.)Afterward, we weighed it and the dry empty weight was 630 lbs.Since then, I have had custom seat and back cushions made,but they are extremely light in weight. I would guess about 4 Lbs.I believe I could save even more weight by using, say, 2.6 oz. fabric with a fine weave. The polyester fabric I used is too heavyat about 3.6 oz. and has a relatively coarse weave, requiringmore dope. It is so strong that I likely would never have to replaceit due to strength loss, but after over 17 years since recover I would like to check the structure. Grade A cotton used to be the standard for aircraft fabric, but was heavier than the syntheticsand deteriorated much more quickly.If I were to build another Pietenpol, I could save even more weight,but I doubt I could beat Brian Kenney's CF-AUK which has an EWsignificantly under 600 lbs.!Graham Hansen (Pietenpol CF-AUN)Alberta, Canada________________________________________________________________________________