Original Posted By: "Adams, Pat E"
Can anyone tell me if Mr. Pietenpol reduced the size of the main spars from 1"to 3/4" ? Also, is the standard type of spar wood still spruce? I have beenunsing cedar for the ribs, and found that the caps will go right into the ribjig, without any steam treatment. I hope to use a corvair engine in theproject and would like to hear about the causes of the engine failures thatsomeone spoke of. Also, has anyone ever heard of a spar failure in a Piet?Oh, yeah...I love hearing the flying stories !!!Chuck Gantzer________________________________________________________________________________
Pietenpol-List: spar size
Pietenpol-List: Re: spar size
Original Posted By: Mike Cunningham
>Can anyone tell me if Mr. Pietenpol reduced the size of the main spars from 1">to 3/4" ? Also, is the standard type of spar wood still spruce? In Grant McLaren's Pietenpol Notebook it is said that the spars on BHP's "LastOriginal" were 3/4" thick Western Hemlock. Of course, they were not routed, but this is still less volume than routed 1" spars. 90% of that ship is douglas fir, but Don Pietenpol says BHP ran out of fir and used hemlock for thespars. Howard Henderson, among others, has used 3/4" douglas fir for spars.It also says in GM's Piet Notebook that BHP laminated spars, using 7 pieces of3/4" x 3/4" material, but it doesn't say if these in particular were the sparsmade of hemlock, since he specified that solid wood is best (not laminated). Here's a quite from BHP that I lifted from GM's Piet Notebook: "Solid spars are preferred if you can get good wood. 3/4 inch solid and put on1/8 inch plywood" [at the attachment fittings]. >I hope to use a corvair engine in the>project and would like to hear about the causes of the engine failures that>someone spoke of.Two reports of Corvair engine failures are from Jim VanDervort in various backissues of the BPAN. He had some sort of engine failure due to using one of those stamped metal crankshaft pulleys instead of a harmonic balancer. He didn't specify what exactly happened to the engine, but it required a deadsticklanding. A second failure was due to a broken rocker arm after allowing the engine to sit unprotected (possibly rusting internally) for a while (he recommends grooved rocker balls, but Corvair experts have discouraged this forour application). I don't think the circumstances of that situation were mentioned, but one could guess that he'd fly the plane on 5 cylinders if necessary. Now, I'm drawing all of this from memory, so it might not be perfectly accurate. --Peter________________________________________________________________________________
>Can anyone tell me if Mr. Pietenpol reduced the size of the main spars from 1">to 3/4" ? Also, is the standard type of spar wood still spruce? In Grant McLaren's Pietenpol Notebook it is said that the spars on BHP's "LastOriginal" were 3/4" thick Western Hemlock. Of course, they were not routed, but this is still less volume than routed 1" spars. 90% of that ship is douglas fir, but Don Pietenpol says BHP ran out of fir and used hemlock for thespars. Howard Henderson, among others, has used 3/4" douglas fir for spars.It also says in GM's Piet Notebook that BHP laminated spars, using 7 pieces of3/4" x 3/4" material, but it doesn't say if these in particular were the sparsmade of hemlock, since he specified that solid wood is best (not laminated). Here's a quite from BHP that I lifted from GM's Piet Notebook: "Solid spars are preferred if you can get good wood. 3/4 inch solid and put on1/8 inch plywood" [at the attachment fittings]. >I hope to use a corvair engine in the>project and would like to hear about the causes of the engine failures that>someone spoke of.Two reports of Corvair engine failures are from Jim VanDervort in various backissues of the BPAN. He had some sort of engine failure due to using one of those stamped metal crankshaft pulleys instead of a harmonic balancer. He didn't specify what exactly happened to the engine, but it required a deadsticklanding. A second failure was due to a broken rocker arm after allowing the engine to sit unprotected (possibly rusting internally) for a while (he recommends grooved rocker balls, but Corvair experts have discouraged this forour application). I don't think the circumstances of that situation were mentioned, but one could guess that he'd fly the plane on 5 cylinders if necessary. Now, I'm drawing all of this from memory, so it might not be perfectly accurate. --Peter________________________________________________________________________________