Original Posted By: Rcaprd(at)aol.com
I'm building my wing center section in the next week or so.My cabanes are on and according to my measurements I currently have 1.5 degreesof incidence.Does this sound good? The GN-1 if built to plans is about 0 degrees.... whichdoesn;t sound right to me.DJwww.imagedv.com/aircamper=This email has been scanned for known viruses and made safe for viewing by Half Price Hosting, a leading email and web hosting provider. For more information on an anti-virus email solution, visit .________________________________________________________________________________
Pietenpol-List: 1.5 degrees incidence
Re: Pietenpol-List: Corvair Engine Mount
Original Posted By: Jim Ash
Subject: Re: Pietenpol-List: Corvair Engine MountIn a message dated 6/27/03 6:54:18 AM Central Daylight Time, dknoll(at)cox.net writes:>Lynn, One important consideration to have, is to determine where your Center of Gravity will be. Bernard Harold Pietenpol was about 150 or 160 lbs (maybe less), and his weight is how he determined the length of the engine mounts thathe built. Lots of people these days weigh much more than that. I think this may be the reason that Pietenpols have the reputation of being tail heavy. The plans by A.C. Hanfet 3-15-67 are the ones I used to Oxy Acy weld my mountto. The changes that were required to give me an acceptable C.G. range was tolengthen it by 8 inches. That's right, EIGHT inches longer than those plans call for. Those plans call for 3/4 X .049 tubing, and 5/8 X .035 tubing. I used 3/4 X .060 tubing, and 5/8 X .060 tubing, to accept the loads of the extralength. (I got the 5/8 from 'The Yard', here in Wichita). I kept the same nose down thrust line called out in the plans - 11 3/16 on the top, and 10 5/8on the bottom. I maintained the same thrust line called out, but I added about 1/8" right thrust to the mount. An engineer friend of mine did a stressanalysis on my design, and he said my mount was over 3 times stronger than required. (attn. - Doc Mosher) I also built four new fittings (eight pieces inall) for the engine mount to the longerons. I used .090, 4130 steel, with four #10 bolts in each one. I have the Short Fuselage, Improved Aircamper. With the Model A Engineballast I cast from lead shot, and bolted to the transmission flange of the Model A, to keep me in a safe C.G. range. It's a really nice casting, that I nolonger need. I still have it, if you know anyone with a Model A that needs it. In that configuration my planes empty weight was 680lbs. Now, with the Continental and extended mount she weights a mere 621 empty !!! She lost almost60 lbs !! She's a slim and trim lady, now !! Very well behaved, too. The way I estimated the engine mount, was all done on paper. I use the firewall as the Datum, so there were negative numbers involved, which can be alittle confusing when the multiplication portion is done. I determined the C.G. of the engine itself, and removed the weight of the Model A at that arm. I then added the weight of the Continental at the arm called out in those plans, but determined that even with my struts slanted back 3 1/2", and me onboard, the C.G. was well aft of the aft limit. That aft limit scares the hellout of me !! 20" aft of the leading edge is 33 1/3% of the chord, aft of the leading edge. That's more than any other plane I've ever seen. On paper, I began adding an inch at a time to the arm of the Continental's weight, until Igot to 8 additional inches, then I was ahead of the aft limit with me onboard, and zero fuel. That's what I built my engine mount to. I didn't know for surethat I did all this stuff right, until I weighed the completed plane, and did my weight and balance...I nailed it RIGHT ON !!! I couldn't believe it !! Now, with zero fuel, and me onboard, it is 1/2" ahead of the aft limit...almostexactly where I estimated it !! No matter what loading configuration, I'm still within the C.G. limits. It appears to have a long nose, compared to theModel A configuration, and I was a little concerned about coming out of a slip,but this isn't the case at all. I've been turning base to final at 300 feet or more, and putting 'er into a slip and a steep decent (60 mph indicated, 1400 rpm), and she comes right out of the slip...no problem. Ya just can't believe how well behaved this plane is!! It is pure Stick & Rudder, and it's rarethat I can fly hands off with the thermals, and winds of Kansas. I LOVE IT ! I now have 11.2 hrs flight time on the new engine. The next time you stop out at Benton, I'll be happy to go over the details of how I determined the length of my engine mount.Hope this helps. Chuck NX770CGTrees & Rags to Stick & Rudder :Pietenpols are Forever !!________________________________________________________________________________Date: Tue, 01 Jul 2003 03:44:10 -0400
Subject: Re: Pietenpol-List: Corvair Engine MountIn a message dated 6/27/03 6:54:18 AM Central Daylight Time, dknoll(at)cox.net writes:>Lynn, One important consideration to have, is to determine where your Center of Gravity will be. Bernard Harold Pietenpol was about 150 or 160 lbs (maybe less), and his weight is how he determined the length of the engine mounts thathe built. Lots of people these days weigh much more than that. I think this may be the reason that Pietenpols have the reputation of being tail heavy. The plans by A.C. Hanfet 3-15-67 are the ones I used to Oxy Acy weld my mountto. The changes that were required to give me an acceptable C.G. range was tolengthen it by 8 inches. That's right, EIGHT inches longer than those plans call for. Those plans call for 3/4 X .049 tubing, and 5/8 X .035 tubing. I used 3/4 X .060 tubing, and 5/8 X .060 tubing, to accept the loads of the extralength. (I got the 5/8 from 'The Yard', here in Wichita). I kept the same nose down thrust line called out in the plans - 11 3/16 on the top, and 10 5/8on the bottom. I maintained the same thrust line called out, but I added about 1/8" right thrust to the mount. An engineer friend of mine did a stressanalysis on my design, and he said my mount was over 3 times stronger than required. (attn. - Doc Mosher) I also built four new fittings (eight pieces inall) for the engine mount to the longerons. I used .090, 4130 steel, with four #10 bolts in each one. I have the Short Fuselage, Improved Aircamper. With the Model A Engineballast I cast from lead shot, and bolted to the transmission flange of the Model A, to keep me in a safe C.G. range. It's a really nice casting, that I nolonger need. I still have it, if you know anyone with a Model A that needs it. In that configuration my planes empty weight was 680lbs. Now, with the Continental and extended mount she weights a mere 621 empty !!! She lost almost60 lbs !! She's a slim and trim lady, now !! Very well behaved, too. The way I estimated the engine mount, was all done on paper. I use the firewall as the Datum, so there were negative numbers involved, which can be alittle confusing when the multiplication portion is done. I determined the C.G. of the engine itself, and removed the weight of the Model A at that arm. I then added the weight of the Continental at the arm called out in those plans, but determined that even with my struts slanted back 3 1/2", and me onboard, the C.G. was well aft of the aft limit. That aft limit scares the hellout of me !! 20" aft of the leading edge is 33 1/3% of the chord, aft of the leading edge. That's more than any other plane I've ever seen. On paper, I began adding an inch at a time to the arm of the Continental's weight, until Igot to 8 additional inches, then I was ahead of the aft limit with me onboard, and zero fuel. That's what I built my engine mount to. I didn't know for surethat I did all this stuff right, until I weighed the completed plane, and did my weight and balance...I nailed it RIGHT ON !!! I couldn't believe it !! Now, with zero fuel, and me onboard, it is 1/2" ahead of the aft limit...almostexactly where I estimated it !! No matter what loading configuration, I'm still within the C.G. limits. It appears to have a long nose, compared to theModel A configuration, and I was a little concerned about coming out of a slip,but this isn't the case at all. I've been turning base to final at 300 feet or more, and putting 'er into a slip and a steep decent (60 mph indicated, 1400 rpm), and she comes right out of the slip...no problem. Ya just can't believe how well behaved this plane is!! It is pure Stick & Rudder, and it's rarethat I can fly hands off with the thermals, and winds of Kansas. I LOVE IT ! I now have 11.2 hrs flight time on the new engine. The next time you stop out at Benton, I'll be happy to go over the details of how I determined the length of my engine mount.Hope this helps. Chuck NX770CGTrees & Rags to Stick & Rudder :Pietenpols are Forever !!________________________________________________________________________________Date: Tue, 01 Jul 2003 03:44:10 -0400