Original Posted By: "coxwelljon"
Thanks Jack,I hope to see you there. My grandson and I enjoyed meeting you last year. Unfortunatelyhe will not be able to come this year but I will be there.--------Jon Coxwell GN-1 BuilderRecycle and preserve the planetRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Corvair on a GN-1
Pietenpol-List: Corvair on a GN-1
Original Posted By: Michael Weston
I l haven't posted lately or followed what was going on but thought I would bringthe list up to date with some issues I have discovered with my GN-1.I bought mine as a partially completed project with a corvair engine supposedlyrebuilt to WW specs. I won't go in to all that I had to do to the engine butthe short answer was totally rebuild it.Last fall I ran the engine at a corvair college and then began to concentrate onthe airframe. My fuselage was built but not covered. I hung the engine onthe airframe and began to work on weight and balance.It is amazing how the subtle changes in geometry that Grega made add up. Puttingthe heavier corvair engine on the GN-1 which was a re-designed Piet for anA-65 makes it extremely nose heavy. The bolt on cub gear is also well behindthe leading edge (9") which I think would make for some potential nose overs ontaxing. I hung the engine on in flight attitude and the tail was definitelynegative. The GN-1 wing is fixed and does not move back and forth like the Piet.My motor mount that came with the project had the engine well out in front,probably 8 to 10" ahead of the firewall. Weight and balance looked horrible.I rebuilt the motor mount which moved the engine back to minimum clearancefrom the fire wall which puts more weight on the tail when in 3 point attitudeon the ground. I then redesigned the vertical cabane attachments so the wingwould rotate like a piet. I then moved the wing back 4" to make the weightand balance work while in the air. I spent a lot of time reading through William Wynne's weight and balance articlesthat appeared in the Brodhead news letter. I recommend anyone building a Pietof GN-1 do this as there is some excellent information there. And if youare building a GN-1 with a corvair do some serious W&B calcs early on. It maysave you a lot of work.All this added probably 6 months to my build time. These are the things you don'tthink about when you buy someone else's project and don't have the benefitof what was in their head while constructing. in my case what was in the headsof at least 3 previous builders. My airplane will no longer be a GN-1 norwill it be a true Piet. I think I will dub it an Adirondack Aircamper in honorof its last home before it flies.Jon CoxwellGN-1, 100 hp corvair--------Jon Coxwell GN-1 BuilderRecycle and preserve the planetRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________
I l haven't posted lately or followed what was going on but thought I would bringthe list up to date with some issues I have discovered with my GN-1.I bought mine as a partially completed project with a corvair engine supposedlyrebuilt to WW specs. I won't go in to all that I had to do to the engine butthe short answer was totally rebuild it.Last fall I ran the engine at a corvair college and then began to concentrate onthe airframe. My fuselage was built but not covered. I hung the engine onthe airframe and began to work on weight and balance.It is amazing how the subtle changes in geometry that Grega made add up. Puttingthe heavier corvair engine on the GN-1 which was a re-designed Piet for anA-65 makes it extremely nose heavy. The bolt on cub gear is also well behindthe leading edge (9") which I think would make for some potential nose overs ontaxing. I hung the engine on in flight attitude and the tail was definitelynegative. The GN-1 wing is fixed and does not move back and forth like the Piet.My motor mount that came with the project had the engine well out in front,probably 8 to 10" ahead of the firewall. Weight and balance looked horrible.I rebuilt the motor mount which moved the engine back to minimum clearancefrom the fire wall which puts more weight on the tail when in 3 point attitudeon the ground. I then redesigned the vertical cabane attachments so the wingwould rotate like a piet. I then moved the wing back 4" to make the weightand balance work while in the air. I spent a lot of time reading through William Wynne's weight and balance articlesthat appeared in the Brodhead news letter. I recommend anyone building a Pietof GN-1 do this as there is some excellent information there. And if youare building a GN-1 with a corvair do some serious W&B calcs early on. It maysave you a lot of work.All this added probably 6 months to my build time. These are the things you don'tthink about when you buy someone else's project and don't have the benefitof what was in their head while constructing. in my case what was in the headsof at least 3 previous builders. My airplane will no longer be a GN-1 norwill it be a true Piet. I think I will dub it an Adirondack Aircamper in honorof its last home before it flies.Jon CoxwellGN-1, 100 hp corvair--------Jon Coxwell GN-1 BuilderRecycle and preserve the planetRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________