Original Posted By: "Cuy, Michael D. (GRC-LME0)[Vantage Partners, LLC]"
Fellow Pietenpolers,Re recent comments about the Riblet airfoil on a Piet.Last year at Broadhead, I gave a forum comparing my built to the plans long fuselage Pietenpol with my friend Don Harpers extended length fuselage Pietenpol built to the plans EXCEPT with the Riblet 612 airfoil along with all the data we learned during the test flying. [ Maybe someone has a hard copy of the information I presented. Maybe they might share with everyone. I'm not sure I kept a copy.]I don't want to try and repeat the forum information here again, nor start an argument As has been said many times, READ THE ARCHIVES The detailed information is there.To answer two questions, here is what we did because there was no information avaliable at that time.1. We both used the Pietenpol plans information to build the cabane struts. The front struts are 1" longer than the rear struts.We also did what most builders do and that was make both front and rear struts 2" longer than the plans call for so the front passenger can get in and out easier. Per the plans, this should give 2 degrees angle of attack.2. Both wings were assembled upside down with the bottom of the ribs against the bottom of the spars. Without going into a very long repeat of the test flight numbers, both planes are flying well. I have about 300 hrs on my plane and Don has about 70 hrs on his. Both planes have a trim system consisting of a bunji cord and adel clamp that slides up and down the control stick for pitch changes. Simple and works well.Anytime you make a throttle change, you also have to make a trim change.My suggestion is....Use either airfoil... build it to the plans ....and it will fly great. P. F.________________________________________________________________________________
Pietenpol-List: Recent question about the Riblet airfoil angle ofattack
Pietenpol-List: Re: Recent question about the Riblet airfoil angle ofattack
Original Posted By: "William Wynne"
William,I found the polars for the Pietenpol airfoil that I had run through the analysissoftware several years ago. Mr. Pietenpol had the length of the cabanes exactlyright for a cruise lift coefficient of .77. By my calculations the frontcabanes should be exactly one inch longer than the rear, which, of course, iswhat the plans call for.In another thread a gentleman stated the Piet he had built with a Riblett 30-612and cabanes built to the plans flew great. With no disrespect to this individualintended, and admittedly not knowing the conditions under which it was flownor the weight of the plane in order to calculate an appropriate cruise liftcoefficient, by my calculations his airplanes angle of incidence is set approximately3 degrees too high. This may explain why it does not perform any betterthan his friends plane with the Pietenpol airfoil despite the evidence thatthe computer simulations indicate that it should. I believe if he were toshorten the front cabanes by 1.5 he would see an improvement in its performance.Doug WrightStillwater, OKRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Recent question about the Riblet airfoil angle ofattack
William,I found the polars for the Pietenpol airfoil that I had run through the analysissoftware several years ago. Mr. Pietenpol had the length of the cabanes exactlyright for a cruise lift coefficient of .77. By my calculations the frontcabanes should be exactly one inch longer than the rear, which, of course, iswhat the plans call for.In another thread a gentleman stated the Piet he had built with a Riblett 30-612and cabanes built to the plans flew great. With no disrespect to this individualintended, and admittedly not knowing the conditions under which it was flownor the weight of the plane in order to calculate an appropriate cruise liftcoefficient, by my calculations his airplanes angle of incidence is set approximately3 degrees too high. This may explain why it does not perform any betterthan his friends plane with the Pietenpol airfoil despite the evidence thatthe computer simulations indicate that it should. I believe if he were toshorten the front cabanes by 1.5 he would see an improvement in its performance.Doug WrightStillwater, OKRead this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: Re: Recent question about the Riblet airfoil angle ofattack