Pietenpol-List: Re: EAA Work Bench

[matronics]

Original Posted By: "johnnysdrop"
Dan asked-> Regardless of the engine choice has anyone ever altered ( moved ) the thrustline> of their PIETENPOL . Either the Angle ( Up, Down, Left, Right) or height> of thrust line in relationship to the top longeron ? What was the result ?Scout's engine mount places the engine thrustline close to where the A65-stylemount calls for it to be, but I have since changed the thrust angles on itby adding washers, shims, and then eventually (when it was dialed in), spacers.Specifically, I added downthrust and offset, and the result has been that theairplane is more nearly a hands-off cruiser than I could ever have imagined.Here are some re-postings of two of my earlier posts on the subject. From 10/6/10:================== I'm just doing this to 41CC now, incrementally. First increment was to offsetthe stab in the direction Jack has stated (to the left, looking forward), by about3/8". I then removed the bent-metal trim tab at the trailing edge of therudder. Flew pretty well but still yawed to the left. Should have offset thestab by 1/2" but no more than that.Next increment was to check engine thrustline and it was zero-zero. I have nowoffset the engine thrustline 2 degrees right and 2 degrees down and althoughit still yaws to the left, it's getting very close now and the stick forces (elevator)in cruise are improved as well. These adjustments were done using enginemount washers, but after I add another 1/2 degree of right thrust, we'regoing to machine some aluminum spacers to replace the washers and we're done.Next will be to play with the bungee tension that I have on the elevator bellcrankfor nose up trim.I never imagined that 41CC might be a hands-off airplane, but it's looking likeit might be possible, in smooth air, with just the right amount of fuel in thetank ;o)================>From 12/26/10:================I concluded vibration testing on my A75 today, with good results.Recall that before balancing, the Dynavibe was showing 0.51 IPSimbalance at 2150 RPM, which was maximum static at the condition onDec. 18. We ran some other tests using a different carb venturiand adjusted the engine thrust line, but those had nothing to dowith the vibration work. An interim test run using longer AN6 propbolts with four stacked washers under the heads resulted in a reductionof vibration to 0.27 IPS at 2150 RPM, with just a slight radialchange in location of the heavy side of the prop. We were on theright track.Today we added a small 'flyweight' clamped between the two prop boltsacross from the side of the prop that the Dynavibe had identifiedas heavy. It was purposely made a bit heavier than we think willbe the final shape of it, allowing for rounding of the edges andthen applying paint (it's 4130 steel). Warmed up the engine andran the Dynavibe averaging again, and achieved 0.07 IPS and nowthe heavy side has shifted radially on the hub, indicating thatwe would be chasing small changes from here on, with very limitedways of offsetting the heaviness. So, we called it more thanjust good (Dynavibe says to shoot for no more than 0.1 IPS).Cowlings back on, engine warmed up, and a test flight in "Scout" wasjust deee-lightful!!! What a joy, not only in the buttery smoothnessof the engine, but leveling out at cruise, the change in enginethrustline offset was very rewarding. Hands off, feet off, halftank of fuel, and the yaw is almost gone... a half-ball of left turning,which a very light touch on the right rudder would stop instantly. Inever thought this would be a hands-off airplane, but it's getting veryclose! We'll reinstall the bent-metal trim tab on the rudder andI'll bet the next flight will show NO yawing tendency with feet offthe rudders. This airplane is getting sweeter with every tweak we giveit. Of course, it was clear and COLD here today (mid-40s) so Scoutclimbed wonderfully, but still- the improvements are noticeable anduseful.Oscar ZunigaAir Camper NX41CC "Scout"Flying Squirrel N2069Z "Rocket"Medford, OR website at http://www.flysquirrel.net ________________________________________________________________________________Subject: Pietenpol-List: Re: EAA Work Bench

[matronics]

Original Posted By: Michael Perez
KringleHow do you level the tables and how will you join them together?They look good!English JohnnyOn rib 13 now.--------The only way is UPRead this topic online here:http://forums.matronics.com/viewtopic.p ... ______Date: Thu, 22 Dec 2011 05:54:53 -0800 (PST)

[matronics]

Original Posted By: Michael Perez