Brodhead Pietenpol Association

Original Posted By: john hodnette
Subject: Pietenpol-List: Re: Spars, Spruce, Fir and Three Piece Wings>Jim Wills in the UK designed a box spar for the Piet. The motivation, I>believe, arises from the fact that spruce prices here are extortionate.>The built up spar offers a considerable cost saving, probably a reasonable>weight saving and, no doubt, contributes to the approved maximum all up>weight of 1200lbs.>>Before you all throw your hands up in horror, Jim had to make a few>(structural) changes to allow the design to be assessed and approved by our>rigourous PFA.>>Anyway, the box dimensions are as follows:>>FRONT>>upper and lower spar caps - 1-1/4" x 7/8"(thickness)>>ply web - 1/8" on one side, with additional web on opposite side and void>filling with spruce where required for strength at attachment points, e.g.>lift struts.>>There is also a 7/8" x 1/2" spruce vertical web stiffener at rib locations.>>REAR>>upper and lower spar caps - 7/8" x 3/4"(thickness)>>ply web and strengthening as above.>>I can't really tell you more than that as I haven't started building it>yet, but Jim would happily sell you his drawings at (I'm sure) a modest>price. He also designed a neat three piece wing with automatic aileron>connection and transport fittings for the wings.>>The whole set of plans, including the original Piet plans cos me 110>sterling - about $160, so his additional drawings shouldn't be too much.>>>>...I think a box spar would even be better, but I wouldn't know>>how to calculate the dimensions, although I found the formulas in the>>wood handbook. 1" box spar would be strong and would have no >hidden>defects.>>Any body know of a comparable aircraft that uses box spars?>Nottinghamshire>England>>leo(at)deadly.demon.co.uk>>________________________________________________________________________________

Original Posted By: jmcnarry(at)techplus.com (John McNarry)
Jim Wills in the UK designed a box spar for the Piet. The motivation, Ibelieve, arises from the fact that spruce prices here are extortionate.The built up spar offers a considerable cost saving, probably a reasonableweight saving and, no doubt, contributes to the approved maximum all upweight of 1200lbs.Before you all throw your hands up in horror, Jim had to make a few(structural) changes to allow the design to be assessed and approved by ourrigourous PFA.Anyway, the box dimensions are as follows:FRONT upper and lower spar caps - 1-1/4" x 7/8"(thickness)ply web - 1/8" on one side, with additional web on opposite side and voidfilling with spruce where required for strength at attachment points, e.g.lift struts.There is also a 7/8" x 1/2" spruce vertical web stiffener at rib locations.REARupper and lower spar caps - 7/8" x 3/4"(thickness)ply web and strengthening as above.I can't really tell you more than that as I haven't started building ityet, but Jim would happily sell you his drawings at (I'm sure) a modestprice. He also designed a neat three piece wing with automatic aileronconnection and transport fittings for the wings.The whole set of plans, including the original Piet plans cos me 110sterling - about $160, so his additional drawings shouldn't be too much.>...I think a box spar would even be better, but I wouldn't know >how to calculate the dimensions, although I found the formulas in the>wood handbook. 1" box spar would be strong and would have no >hiddendefects. >Any body know of a comparable aircraft that uses box spars?NottinghamshireEnglandleo(at)deadly.demon.co.uk________________________________________________________________________________

Original Posted By: Gordon Brimhall
Sorry, I was being a little naughty - I wanted to see if anyone showed anyinterest.Jim can be contacted at the following address (he has no online presencethat I am aware of).Jim Wills1, Humber RoadBlackheathLONDONSE3 7LTUnited Kingdom>Leo, How do we contact Jim Wills?>>-----Original Message----->From: Leo Ponton >To: Pietenpol Discussion >Date: Friday, October 01, 1999 6:14 AM>Subject: Re: Spars, Spruce, Fir and Three Piece Wings>>>>Jim Wills in the UK designed a box spar for the Piet. The motivation, I>>believe, arises from the fact that spruce prices here are extortionate.>>The built up spar offers a considerable cost saving, probably a reasonable>>weight saving and, no doubt, contributes to the approved maximum all up>>weight of 1200lbs.>>>>Before you all throw your hands up in horror, Jim had to make a few>>(structural) changes to allow the design to be assessed and approved by our>>rigourous PFA.>>>>Anyway, the box dimensions are as follows:>>>>FRONT>>>>upper and lower spar caps - 1-1/4" x 7/8"(thickness)>>>>ply web - 1/8" on one side, with additional web on opposite side and void>>filling with spruce where required for strength at attachment points, e.g.>>lift struts.>>>>There is also a 7/8" x 1/2" spruce vertical web stiffener at rib locations.>>>>REAR>>>>upper and lower spar caps - 7/8" x 3/4"(thickness)>>>>ply web and strengthening as above.>>>>I can't really tell you more than that as I haven't started building it>>yet, but Jim would happily sell you his drawings at (I'm sure) a modest>>price. He also designed a neat three piece wing with automatic aileron>>connection and transport fittings for the wings.>>>>The whole set of plans, including the original Piet plans cos me 110>>sterling - about $160, so his additional drawings shouldn't be too much.>>>>>>>>>...I think a box spar would even be better, but I wouldn't know>>>how to calculate the dimensions, although I found the formulas in the>>>wood handbook. 1" box spar would be strong and would have no >hidden>>defects.>>>Any body know of a comparable aircraft that uses box spars?>>Nottinghamshire>>England>>>>leo(at)deadly.demon.co.uk>>>>>>NottinghamshireEnglandleo(at)deadly.demon.co.uk________________________________________________________________________________

Original Posted By: Leo Ponton
Leo, How do we contact Jim Wills?-----Original Message-----