Brodhead Pietenpol Association

Original Posted By: "skellytown flyer"
My own take on it is that the spar orientation should berelative to the chord line of the selected airfoil. Thequirk in the deal is that some of the older airfoils werereferenced to a line along the bottom, which made some sensewith flat-bottomed airfoils like the USA35. However,camber and cusp change the picture, plus the fact that allmodern airfoils and all analysis programs reference themean aerodynamic chord (I believe). In any case, the Riblettis not a flat-bottomed airfoil and all of its publishedcharacteristics are referenced to the chord.I wish the world was simple again, like it used to be ;o)Oscar ZunigaAir Camper NX41CCSan Antonio, TXmailto: taildrags(at)hotmail.comwebsite at http://www.flysquirrel.net ________________________________________________________________________________Subject: Pietenpol-List: static thrust

Original Posted By: "Peter W Johnson"
if anybody is interested enough to spend some money for a tester-there is one onE-bay that looks pretty nice in the aircraft parts site.it has a 400# range.probablyimported but should b fairly accurate. RaymondRead this topic online here:http://forums.matronics.com/viewtopic.p ... __________

Original Posted By: helspersew(at)aol.com
Peter,I've looked at Piet plans and it helped to clarify some dimensions, I'm drawingon, give me a day or two to finish it.My question was so stupid - you haven't seen what is puzzling me, but let me embaracemy self again and put it differently: when you build the whole front spar,and the spar box has so called "U" shape, do you rotate the bottom of theletter "U" towards the tip of the wing, not towards the rear spar?Regards,IvanRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Re: Pietenpol-List: static thrustDate: Thu, 19 Nov 2009 19:49:50 -0500

Original Posted By: gliderx5(at)comcast.net
A lower-pitch prop will give you higher static RPM and greater static thrust. If you are otherwise happy with the prop, that's the only change needed. Besides, your next prop will be faster to make and possibly better, right?David Paule ----- Original Message -----

Original Posted By: gliderx5(at)comcast.net
As long as the diameter is not too large for the maximum rpm, greater diameter is more efficient.If you imagine a graph of speed on the horizontal axis and efficiency on the vertical axis, increasing the diameter causes the efficiency to go up. Lowering the pitch causes the efficiency to occur at a lower speed. Of course you've got to make sure that your prop isn't too long for the engine. And that takes a balance between pitch and diameter, plus some of the art of building props. And that art, alas, is beyond me. I'm merely an engineer.David Paule ----- Original Message -----

Original Posted By: Matt Dralle

Original Posted By: Rick Holland
Subject: Re: Pietenpol-List: static thrust