---------------------------------------------------------- Pietenpol-List Digest Archive --- Total Messages Posted Wed 06/01/05: 25 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:07 AM - flight testing Greg/Dale's plane (Oscar Zuniga) 2. 07:05 AM - Re: flight testing Greg/Dale's plane () 3. 07:59 AM - Why lower the leading edge of the stabiliser? (Christian Bobka) 4. 08:11 AM - Re: [Flitzer-Builders] Second Pilot report (Christian Bobka) 5. 08:22 AM - Second pilot report comments (Christian Bobka) 6. 08:23 AM - More comments on second pilot report (Christian Bobka) 7. 08:24 AM - More comments from a noted European aircraft designer (Christian Bobka) 8. 09:41 AM - dihedral (Michael D Cuy) 9. 09:44 AM - flight testing Greg/Dale's plane (Oscar Zuniga) 10. 10:49 AM - Final comments to Mark Crawford the Aussie's post at the bottom (Christian Bobka) 11. 11:15 AM - Cork float fuel-proof varnish? (Steve Ruse) 12. 11:18 AM - Re: Cork float fuel-proof varnish? (Phillips, Jack) 13. 11:26 AM - Re: Cork float fuel-proof varnish? (Michael D Cuy) 14. 11:49 AM - offset thrust line (Oscar Zuniga) 15. 12:01 PM - Carb heat on the Piet (Christian Bobka) 16. 12:56 PM - Re: flight testing Greg/Dale's plane (Textor, Jack) 17. 01:20 PM - Re: Tailwheel control schemes (John E. Joyce) 18. 03:55 PM - Urbana (Isablcorky@AOL.COM) 19. 04:34 PM - Re: Urbana (Larry Nelson) 20. 05:36 PM - Grove Wheels/Brakes (Lynn Knoll) 21. 05:39 PM - Re: dihedral (Galen Hutcheson) 22. 06:49 PM - Re: Urbana (Christian Bobka) 23. 09:13 PM - Re: Cork float fuel-proof varnish? (Rcaprd@aol.com) 24. 10:51 PM - Re: Second Pilot report (Rcaprd@aol.com) 25. 11:16 PM - We mean the same thing (Christian Bobka) ________________________________ Message 1 _____________________________________ Time: 06:07:22 AM PST US From: "Oscar Zuniga" Subject: Pietenpol-List: flight testing Greg/Dale's plane --> Pietenpol-List message posted by: "Oscar Zuniga" Chris wrote- >changed the attack angle of the stabiliser by loosening up the front top >turnbuckles by two turns and tightening the two lower front turnbuckles >two turns. This had the effect of increasing the attack angle of the >stabiliser >making it more agressive in holding the nose up. Wait. Wouldn't this *lower* the leading edge of the horizontal stabilizer? That would indeed have the effect of making the nose go up. Oscar Zuniga San Antonio, TX mailto: taildrags@hotmail.com website at http://www.flysquirrel.net ________________________________ Message 2 _____________________________________ Time: 07:05:29 AM PST US From: Subject: Re: Pietenpol-List: flight testing Greg/Dale's plane --> Pietenpol-List message posted by: The stabilizer is already pushing down so lowering the LE would, indeed, change the angle of incidence and increase the angle of attack. Greg Cardinal ----- Original Message ----- From: "Oscar Zuniga" Subject: Pietenpol-List: flight testing Greg/Dale's plane > --> Pietenpol-List message posted by: > "Oscar Zuniga" > > Chris wrote- > >>changed the attack angle of the stabiliser >>by loosening up the front top >>turnbuckles by two turns and tightening the >>two lower front turnbuckles >>two turns. This had the effect of >>increasing the attack angle of the >>stabiliser >>making it more agressive in holding the >>nose up. > > Wait. Wouldn't this *lower* the leading > edge of the horizontal stabilizer? That > would indeed have the effect of making the > nose go up. > > Oscar Zuniga > San Antonio, TX > mailto: taildrags@hotmail.com > website at http://www.flysquirrel.net > > > Forum - > Navigator to browse > Subscriptions page, > Browse, Chat, FAQ, > > > ________________________________ Message 3 _____________________________________ Time: 07:59:33 AM PST US d="scan'208"; a="1063437891:sNHT26025756" From: "Christian Bobka" "Flitzer" Subject: Pietenpol-List: Why lower the leading edge of the stabiliser? --> Pietenpol-List message posted by: "Christian Bobka" Oscar Oscar Oscar, Stand off of the LEFT wing tip about 30 feet and look at the airplane. It should have the nose left and the tail right. From this perspective, the pitching moment of the airfoil would be anticlockwise. In other words, the center of pressure, defined as the point under the wing's airfoil where all the air can be assumed to act, is aft of the center of gravity, the point at which all the mass can be assumed to be positioned. If the center of gravity is positioned at 19.5" aft of the leading edge and the center of pressure is located at the 25% or the 1/4 chord point, as it is on most airfoils, then a rotation is set up where the wing wants to flip nose over and over. We see this when the wing comes off of our Sleek Streak rubber powered 25 cent model that we flew as kids. The wing flips over and over on the way down. Therefore, the stabiliser acts downward to counter this rotation. Acting downward means that it acts as an inverted wing. Lowering the leading edge of the stabiliser works to increase ITS angle of attack, giving it more bite into the air helping to force the tail down. We, in effect, "washed in" the stabiliser. Taking it further, assume a ship that looks like a Piet weighs 1000 lbs loaded to fly. At our flight speed, the pitching moment of this ship's airfoil is rather large requiring a 100 pound aerodynamic downforce at the tail to keep the nose from tucking under. The wing now has to lift not only the 1000 pound weight of the ship but also needs to "lift" against the 100 pound downforce of the stabiliser. Therefore, the wing is providing 1100 pounds of lift to fly a 1000 pound airplane. Lift is not free and the two penalties are imposed is in the form of additional parasite drag due to the wing being sized to carry 1100 pounds instead of 1000 pounds and, more importantly and more significantly, the induced drag is commensurate with 1200 pounds of lift not 1000 pounds of lift like you might think. Wait, 1200 pounds? That is 20% higher induced drag than one would think! Yes, 1200 pounds because you are producing 1100 pounds worth of induced drag at the wing and 100 pounds worth of induced drag at the stabiliser. Induce drag is induced drag, it results whether the lift vector is up or down and they do not cancel each other out! The reason Burt Rutan revived the concept of the canard is so that both airfoils are working the same way and not against each other. Put the tail in the front and now it can lift to hold the nose up. If the ship wieghs 1000 lbs, now you can have the wing holding up 900 pounds and the canard holding up the 100 pound pitching moment yielding a total induced drag commensurate with 1000 pounds of lift, the ships weight, which is 5/6 of the case of the tail mounted stabiliser, a significant drag reduction. The wing area can be now be reduced as it only holds up 900 pounds vice 1100 pounds, saving weight, which reduces the induced drag, increases the range and/or payload, etc.. Flitzer los! Chris Chris Braumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message ----- From: "Oscar Zuniga" Subject: Pietenpol-List: flight testing Greg/Dale's plane > --> Pietenpol-List message posted by: "Oscar Zuniga" > > Chris wrote- > > >changed the attack angle of the stabiliser by loosening up the front top > >turnbuckles by two turns and tightening the two lower front turnbuckles > >two turns. This had the effect of increasing the attack angle of the > >stabiliser > >making it more agressive in holding the nose up. > > Wait. Wouldn't this *lower* the leading edge of the horizontal stabilizer? > That would indeed have the effect of making the nose go up. > > Oscar Zuniga > San Antonio, TX > mailto: taildrags@hotmail.com > website at http://www.flysquirrel.net > > ________________________________ Message 4 _____________________________________ Time: 08:11:34 AM PST US d="scan'208,217"; a="969252404:sNHT140902746" From: "Christian Bobka" "Pietenpol" Subject: Pietenpol-List: Re: [Flitzer-Builders] Second Pilot report Mark, We will test your concept in due time and after the left turning tendency is removed. The problem is that we are at some physical limits as far as the airframe is concerned. I am afraid that if I add more downthrust now, then at 2000 rpm in cruise, the nose will want to take on a nose down attitude due to the additional downthrust. This would normally be countered by lowering the leading edge of the horizontal stabiliser which we can't lower much more by twisting the LE unless we do a bunch of work at the tail. There is no provision for shimming or unshimming the horizontal stabiliser as there is on the Flitzer. As the stabiliser sits on the longeron, lowering the stabiliser front attach point is not an option. We would instead have to raise the rear spar of the stabiliser. Doing this would require a reposition of the rudder hinge that is on the tail post or that is on the rudder which would be difficult. Eventually, these fixes will need to be incorporated. But that is what winter is for! We are in flying season now! Flitzer los! Chris Braumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message ----- From: Mark Crawford To: Flitzer-Builders@yahoogroups.com Sent: Wednesday, June 01, 2005 9:39 AM Subject: Re: [Flitzer-Builders] Second Pilot report I'm no expert on this matter, but in model aircraft (R/C and free flight) if the aircraft is climbing a lot with the increasing of power (esp, if tailplane and wing incidence has been addressed) it normally indicates a need for more engine downthrust. Just my 2 cents - don't kill yourself on my advice :P Mark ----- Original Message ----- From: Christian Bobka To: Flitzer-Builders@yahoogroups.com Sent: Wednesday, June 01, 2005 10:11 PM Subject: Re: [Flitzer-Builders] Second Pilot report Lynn, I agree. The enlargement of the vertical stabiliser was recommended in the first pilot report. A bigger rudder to match was not mentioned by me, though, but would be commensurate. The fixed portion is the part that is undersized (undersised?), though, so that should be emphasised. Bernard Pietenpol did not have any dihedral in any of his ships, like Lindbergh's NYP or the original Monocoupe/Monoprep, all contemporaries. Many of the builders think the wing looks like it sags to the point of being drooped at the tips so they insist on having dihedral. If it were up to me, I would build it with zero dihedral as it looks the period amd it is what the designer wanted. Greg is adamant on keeping the tips up. Sad. Thanks for the input. I will send it on to Greg and Dale. Financially, it would not be much to effect a change in the verticals. It is merely the price of the wood, fabric, and paint and the time to do the work. All the fitting could be retained. This might be 100 dollars/50 pounds. No reinspection needed under the current rules! At the same time, a shim under the rear spar of the horizontal stabiliser could be accomodated to make the corrections more permanemt. Again, no reinspection needed under the current rules! Move to the US! Cheers, Chris Braumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message ----- From: Lynn Williams To: Flitzer-Builders@yahoogroups.com Sent: Wednesday, June 01, 2005 4:10 AM Subject: Re: [Flitzer-Builders] Second Pilot report Chris, Regarding some of the trimming problems, as yaw and roll are connected, and these to dihedral effect, since you cannot and need not increase dihedral without further centre-of-drag issues, then the best solution to some of the wayward characteristics might be an enlarged fin and rudder with zero dihedral. Although that may not be really practical from a financial point of view, it would at least mean that the offset-thrust could be minimised, so the cowling need not be re-made. Lynn ----- Original Message ----- From: walter mitchell To: Flitzer-Builders@yahoogroups.com Sent: Wednesday, June 01, 2005 7:06 AM Subject: Re: [Flitzer-Builders] Second Pilot report A caution for those of us who would casually modify a proven design! -Von Schneer ----- Original Message ----- From: Christian Bobka To: pietenpol-list@matronics.com ; Paul Shenton ; Pete Gavin ; Flitzer Sent: Tuesday, May 31, 2005 10:54 PM Subject: [Flitzer-Builders] Second Pilot report There is a lot of good news to report on Greg and Dale's Pietenpol. This past weekend, we took Chuck Gantzer's and other folks' from around the world advice and changed the attack angle of the stabiliser by loosening up the front top turnbuckles by two turns and tightening the two lower front turnbuckles two turns. This had the effect of increasing the attack angle of the stabiliser making it more agressive in holding the nose up. At 2000 rpm or so, the pitch is now in trim in level cruising flight with no forward or aft pressure required to hold a constant altitude/attitude. At cruising speed, if you increase the power above 2000 rpm, the nose goes up. If you pull the power to an amount less than 2000 rpm, the nose will drop. It is obvious from this that the center of thrust is not colocated with the center of drag, the C of T being below the C of D. I identify this as a negative side effect of lengthening the cabane struts and adding dihedral. The induced and parasitic drag of the wing is a large component of the total drag of the ship. As the wing is moved higher and higher above the fuselage, it moves the center of drag up. We are trying to move the C of T and the C of D closer together, not farther apart. Ideally, they would be colocated. I would recommend that if you plan to raise the wing an inch or more from stock location, then raise the thrust line by a like amount to keep the C of D and C of T relationship intact. I have recommended to Dale and Greg that they remove the dihedral to help lower the center of drag. If the tips are 2" higher than the root, it has the undesireable effect of raising the wing an average of yet another inch. As for power setting in cruise, the airplane seems to be very comfortable at 2000 rpm. The way the power setting effects pitch could be worrisome for a first time flyer as a departure stall could easily occur unless briefed of the phenomenon ahead of time. You could "fly the ship off the ground" only to experience a nose up movement due to the low thrust line that could put you right into a low altitude stall. Dick Navratil warned me of this as it has bitten him more than once but he also said that once you know what to do, it is easy to handle, and that is what I have found. I fly the initial climb out right where the red turns to white on the Johnson airspeen indicator. This is backed up by the site picture of the top of the J-3 style eyebrows being held right on the horizon. At 2000 rpm, right rudder pedal deflection of about 1/2" to 1" is still required to hold the ball centered. A little left wing heaviness was still being experienced early in the day. In addition, it also seemed that whenever a upward vertical gust was encountered, it was always the right wing that raised up and not the left. Over the course of the day, the right rear strut was lengthened a total of two turns on top of adjustments made the previous weekend. After the above adjustments to the stabiliser and the wing strut, if power is removed to about 13-1500 rpm in order to approximate a zero thrust glide, and with hands off the stick, the nose will drop and stay dropped as speed is gained. It does not appear to try to recover or raise the nose without adding power to get some thrust acting to pitch the nose up. This is at least to the speed that I have tested it to which is 80 mph as indicated on the Johnson airspeed indicator. In addition, with power at this 13-1500 rpm setting, the aircraft would not need any rudder input nor would it need any roll input. I am pretty sure that the wing heaviness is now fully corrected. It is difficult to separate rudder and roll inputs as they are so related but I think that doing the neutral thrust glides helps to iron this out. We have taken all the shims out of the motor mount on its right side but it is apparent that we still need more right thrust to get rid of the remaining right rudder that must be held at cruise. The next change to be made will be to add 1/8" shims at top left and bottom left. We are almost to the point where the cowling does not fit anymore! Believe me when they tell you how much right thrust you need. It will be a lot! I also tried a few power-on (2000 rpm) and -off (idle) full rudder side slips while at altitude to see how the ship would recover. Initial recovery technique was by removing my foot completely from the fully displaced rudder. She would slowly return to normal attitude and would positively do so. Of course, this is still tainted in the power-on condition by the need for yet more right thrust. As Forrest said, she may be loathe to recover briskly unless postive input is made. Power-on recovery was a lot better than power-off. She has so much drag on final that pulling the power to idle and pointing agressively down will give a good rate of descent at a constant airspeed so slips to landing should not be often necessary. The final item to mention is that the motor feels like it is trying to tumble a bunch of rocks in a rock tumbler. The ship sports a homemade propeller that Dale made. The prop is copied from an old Sensenich 7242 prop and turns 2200 rpm flat out level. I have a spare Sensenich W70DK-42 with only 20 hours on it since new about 4 years ago that we will try out. This will enable us to determine whether the homemade prop is out of balance and whether it should be reshaped to get more RPM. Like his nose bowl, the leading edge on Dale's creation is rather blunt. Rounding the leading edge more may give us the needed 100 rpm to make rated power. The W70DK42 propeller is normally used on an A-75 powered Taylorcraft. I have a few other props to try out and once the best is found, we will have Dale consider another winter prop project. Total time now is 6:28 up from 3:40 the previous week. Flitzer los! Chris For Flitzer FAQs and much more, visit the Flitzer Sportflug Verein (Flitzer Sport Flying Association) site at http://www.av8rblake.com/flitzer/ For Flitzer FAQs and much more, visit the Flitzer Sportflug Verein (Flitzer Sport Flying Association) site at http://www.av8rblake.com/flitzer/ For Flitzer FAQs and much more, visit the Flitzer Sportflug Verein (Flitzer Sport Flying Association) site at http://www.av8rblake.com/flitzer/ For Flitzer FAQs and much more, visit the Flitzer Sportflug Verein (Flitzer Sport Flying Association) site at http://www.av8rblake.com/flitzer/ a.. To visit your group on the web, go to: http://groups.yahoo.com/group/Flitzer-Builders/ b.. To unsubscribe from this group, send an email to: Flitzer-Builders-unsubscribe@yahoogroups.com ________________________________ Message 5 _____________________________________ Time: 08:22:55 AM PST US d="scan'208,217"; a="1152996296:sNHT19659096" From: "Christian Bobka" Subject: Pietenpol-List: Second pilot report comments Chris, Regarding some of the trimming problems, as yaw and roll are connected, and these to dihedral effect, since you cannot and need not increase dihedral without further centre-of-drag issues, then the best solution to some of the wayward characteristics might be an enlarged fin and rudder with zero dihedral. Although that may not be really practical from a financial point of view, it would at least mean that the offset-thrust could be minimised, so the cowling need not be re-made. Lynn ________________________________ Message 6 _____________________________________ Time: 08:23:52 AM PST US d="scan'208,217"; a="964387044:sNHT61060554" From: "Christian Bobka" Subject: Pietenpol-List: More comments on second pilot report Lynn, I agree. The enlargement of the vertical stabiliser was recommended in the first pilot report. A bigger rudder to match was not mentioned by me, though, but would be commensurate. The fixed portion is the part that is undersized (undersised?), though, so that should be emphasised. Bernard Pietenpol did not have any dihedral in any of his ships, like Lindbergh's NYP or the original Monocoupe/Monoprep, all contemporaries. Many of the builders think the wing looks like it sags to the point of being drooped at the tips so they insist on having dihedral. If it were up to me, I would build it with zero dihedral as it looks the period amd it is what the designer wanted. Greg is adamant on keeping the tips up. Sad. Thanks for the input. I will send it on to Greg and Dale. Financially, it would not be much to effect a change in the verticals. It is merely the price of the wood, fabric, and paint and the time to do the work. All the fitting could be retained. This might be 100 dollars/50 pounds. No reinspection needed under the current rules! At the same time, a shim under the rear spar of the horizontal stabiliser could be accomodated to make the corrections more permanemt. Again, no reinspection needed under the current rules! Move to the US! Cheers, Chris ________________________________ Message 7 _____________________________________ Time: 08:24:49 AM PST US d="scan'208,217"; a="964388605:sNHT427261200" From: "Christian Bobka" Subject: Pietenpol-List: More comments from a noted European aircraft designer In Greg's position, I'd zero-out the dihedral and build a 'false leading edge' extension onto the fin, keeping the rudder as is, or maybe adding a fixed rudder tab, to provide a bit moe bite perhaps. The 'false leading edge' would be fitted temporarily, but of course, very carefully and safely so it doesn't come adrift, and see what happens to the handling. Ultimately a new fin could be fabricated as you've suggested, which would still convey the character of the Pietenpol. I think the 'drooping' effect created by the zero dihedral wing, while not uncommon among straight winged biplanes, parasols, an high-wingers, is partly due to the airfoil section which near the tip, due to the high undercamber and parallel chord with a squarish tip, creates a 'downswept' effect from some angles. I don't see anything wrong with this, which is anyway redolent of so many classic types from that era, the Ryan NYP, Brougham, and American Eagle being excellent examples. Cheers, Lynn ________________________________ Message 8 _____________________________________ Time: 09:41:14 AM PST US From: Michael D Cuy Subject: Pietenpol-List: dihedral --> Pietenpol-List message posted by: Michael D Cuy sure makes it easier to pee in a bottle by steering with your feet while your hands are busy. Beats stopping for fuel when you don't have to on an x-country and wasting 45 minutes:) Mike C. ________________________________ Message 9 _____________________________________ Time: 09:44:34 AM PST US From: "Oscar Zuniga" Subject: Pietenpol-List: flight testing Greg/Dale's plane --> Pietenpol-List message posted by: "Oscar Zuniga" Chris (and others)- thanks for the explanation; perfectly clear! I guess what threw me off was the notion that the tailplane is acting as an inverted wing to provide downforce to the tail, thus in fact lowering the leading edge (relative to terra firma) INCREASES the angle of attack of the horizontal stabilizer. Got it! Funny thing is, I guess I'll be facing this same issue once 41CC is back in the air. Corky had fitted both a fixed elevator trim tab and an adjustable bungee around the control stick to apply variable back pressure to the stick while in level cruise, it requiring steady back pressure to keep the nose up in cruise. I can also shim the engine to adjust the thrustline (it's off the mount at the moment). To my knowledge though, the HS is presently rigged straight and level, so I can still add the two turns or so on the turnbuckles at the HS to 'wash it in' as you've done on Greg/Dale's plane, as a first step. Oscar Zuniga San Antonio, TX mailto: taildrags@hotmail.com website at http://www.flysquirrel.net ________________________________ Message 10 ____________________________________ Time: 10:49:11 AM PST US d="scan'208,217"; a="964293442:sNHT51107084" From: "Christian Bobka" Subject: Pietenpol-List: Final comments to Mark Crawford the Aussie's post at the bottom Mark, Maybe there is a reason WHY the rudder in the plans is longer than the tail post plus the horizontal stabiliser thickness plus the vertical stabiliser height. As Greg pointed out to me the other day, there is room AVAILABLE for a shim if only the lower rudder hinge could be easily repositioned. Mark, In many ways I agree with your statement. The ship originally was short nosed and made for the heavy Model A Ford, then adapted to a Corvair and a small Continental which messes up the vertical surface area proportions with those motors' lighter weight and needed extended nose. Then people got bigger so they can't get in and out so they raised the wing and shifted it aft and added a flop for access, and then the ship needed the axle moved to make it handle on the ground, and then the aft shifted wing, gear, payload, and resulting CG upsets the tail moment arm (tail volume if you will) of the stabilisers so they are undersized now and effectively getting smaller as time goes on. Then the plane is yet heavier with the three piece wing which causes it to cruise it at a higher angle of attack which increases the pitching moment which calls for a bigger horizontal stabiliser that nobody is willing to give it. For these reasons, although I appreciate the Peitenpol design for what it was and is, it has lost its attractiveness for my purposes although it can get the builder in the air cheaply, and probably the cheapest, if that is where he wants to be. And I don't blame him for wanting to be there but the choice should be rethought. Palns are virtually free and so is the advice which is worth what you pay for it. It took I few years for me to make the realiasation that too many changes have made the design get to the point where it should be redesigned from a clean sheet of paper, sized and proportioned to be of utmost utility in the future. They are barely true Pietenpols anymore and all the accomodations and bandaids speak of this and detract from the excellence of the no longer adequate original. That is why I have become such a proponent of Lynn William's Staaken Flitzer line as the aircraft fit today's people, use today's available and reliable motors (does not the Ferdinand Porche flat four date to 1914 or something like that? So much for today's motors) like the mere 50 year old Corvair, Rotec R2800, Aerovee, etc,, yet look REALLY good and period, fly well, and can be constructed using the same EXACT traditional methods as the Pietenpol and just as inexpensively. We have it all in the Flitzer line including the cult status the Pietenpol enjoys. We just need to get the word out. Much fame could be had (and maybe some money, Gary) if a gifted designer took all the old classics and made them again viable by upsizing them 10-15% or even 20% and adding 75 years of design experience to economise on the structure while preserving the ORIGINAL construction methods and handling: Buhl Bull Pup, Long Longster, Georgias Special, Pietenpol Camper and Scout, Heath Baby Bullet and Parasol, American Eaglet, Church Midwing, Chilton DW1, UT-1, Urbitis' ships, and the list goes on and on. Just look at original editions of the Flying and Glider Manual (not the chopped up EAA editions that are missing half of the original content). The demand is there but nobody with the ability has stepped up to the plate except Lynn and he is overwhelmed. I wish I had the ability but lack the schooling and the process is yet still mystifying to me. For all the books I have, a hands on, start to finish design has never been put in book form to the extent that I believe necessary for me to be able to copy the technique and eventually be able to do it on my own. Hiscocks or Pazmany come closest but use sheet metal as the medium which is personally undesireable . This book form analysis would have to include flight testing and retrospective design analysis as a result of the corrections made in the field as a result of flight testing. I am truly jealous of the engineer's abilities! It seems that there is a plethora of magazine articles or series of articles that nibble at the design process yet never stick to it through to the end. It is apparent that few individuals possess the designer's ability. Piper figured it out as 10 years after the J-3 Cub, they upsized it to the PA-18 Super Cub, and that was after upsizing it to the J-5 and PA-12 and PA-14. I could imagine that the 1929 Piet with a Model A motor and one piece wing built to the Hoopman plans (really! yeah right) and flown by a 150 pound pilot flies as sweet as can be. But that design is no longer realistic for today's sized people. Mike, don't pee on yourself. And don't forget to zip and don;t get Roscoe caught in the zipper. Guys, don't shake his hand after he climbs out of his ship and don't drink any Mountain Dew he may offer you. Uric acid eats at the wood so be careful of structural deterioration... Inspect and rinse often. I am not advocating building a GN-1..... Flitzer los! Chris Braumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message ----- From: Mark Crawford To: Flitzer-Builders@yahoogroups.com Sent: Wednesday, June 01, 2005 10:25 AM Subject: Re: [Flitzer-Builders] Second Pilot report What a bloody stupid design! Adjusting of tailplane incidence is a pretty important thing -esp. when homebuilt aircraft are concerned (diff materials, workmanship, quality, accuracy, engines, etc). As I said "I'm no expert" but at least the Flitzer has a pretty simple method of adjustment. Good to hear that the original problems have at least been reduced. At least the Piet is a tried and true design - even without the adjustable tailplane. We are getting into our winter now, so have fun in the sun you dogs :P Mark ________________________________ Message 11 ____________________________________ Time: 11:15:50 AM PST US From: Steve Ruse Subject: Pietenpol-List: Cork float fuel-proof varnish? --> Pietenpol-List message posted by: Steve Ruse I am replacing the cub-style fuel guage rod in my plane, and would like to re-coat the cork while I have it out. There are a few chips in the existing varnish, and I want to make sure it doesn't start absorbing fuel and sink in-flight, as I've been told this can happen. Thanks, Steve Ruse N6383J - KFTW ________________________________ Message 12 ____________________________________ Time: 11:18:18 AM PST US Subject: RE: Pietenpol-List: Cork float fuel-proof varnish? From: "Phillips, Jack" --> Pietenpol-List message posted by: "Phillips, Jack" I coated mine with Stit's Epoxy Varnish, as I've found that stuff to be as near bulletproof as any coating I've seen Jack Phillips --> Pietenpol-List message posted by: Steve Ruse I am replacing the cub-style fuel guage rod in my plane, and would like to re-coat the cork while I have it out. There are a few chips in the existing varnish, and I want to make sure it doesn't start absorbing fuel and sink in-flight, as I've been told this can happen. Thanks, Steve Ruse N6383J - KFTW ________________________________ Message 13 ____________________________________ Time: 11:26:16 AM PST US From: Michael D Cuy Subject: Re: Pietenpol-List: Cork float fuel-proof varnish? --> Pietenpol-List message posted by: Michael D Cuy Steve-- upon the advice of my IA and several restoration guys at our airport, I dipped my cork in a can of shellac, let it dry and repeated this about 4 times. No chips or troubles (like not floating) in almost 7 years of using avgas and a rare dose of autofuel. I did re-coat the cork about 2 years ago just to make sure she had a good seal. Shellac is light too--epoxies can become heavy I think. Let's hear what the other experts might have to say though before you take my word:) Mike C. ________________________________ Message 14 ____________________________________ Time: 11:49:30 AM PST US From: "Oscar Zuniga" Subject: Pietenpol-List: offset thrust line --> Pietenpol-List message posted by: "Oscar Zuniga" As a bit of a support to what Chris said about engine thrustline and how it affects handling and feel, here's a snip from a post from William Wynne on this subject. It originally related to where to set the Corvair engine in the Piet, but the comments are general as well. ================= Reply from WW: My Pietenpol had the short 1933 fuselage. The cabane struts were vertical. The empty weight of the plane was 732lbs., measured on electronic scales. It had a full electrical system, brakes, tailwheel, etc. The distance from the firewall to the rear bolt hole was 15". If you are building a newer fuselage, this will be several inches less. I highly recommend the longer fuselage. When my plane was painted orange, the thrust line was in the stock location. When it was blue and silver, I built a new mount which moved the thrust line up to be in line with the top longeron. It flew slightly better that way, and I think it looked a lot better... build the motor mount to give you the correct CG with an appropriately weighted pilot in his seat. We set this perfectly when I built the second motor mount. With a 150lb. pilot, the CG was at 15"; with a 300lb. pilot, the CG was at 20". The axels were at the leading edge of the wing. The plane had excellent ground handling and flew well. ================== Oscar Zuniga San Antonio, TX mailto: taildrags@hotmail.com website at http://www.flysquirrel.net Oscar Zuniga San Antonio, TX mailto: taildrags@hotmail.com website at http://www.flysquirrel.net ________________________________ Message 15 ____________________________________ Time: 12:01:39 PM PST US d="scan'208,217"; a="1064122366:sNHT29667146" From: "Christian Bobka" Subject: Pietenpol-List: Carb heat on the Piet Oscar writes: From: "Oscar Zuniga" > Chris- is this Greg and Dale's Piet (see photo)? If so, I'd like to know > how the carb heat is working on it. My rebuilt exhaust stacks will be > similar to this and I'm curious to know how well theirs works. I meant to talk of this in the second pilot report. I get about a 20 rpm drop when the carb heat is turned on so I would deem it inadequate in its present configuration. I just looked at Bingelis' Firewall Forward, around pages 109 plus or minus a few, and he is silent on the minimum rpm drop. My Cessna 140 gives a 100 rpm drop at 1700 rpm. My Continental books all do not indicate a drop required. The way Greg and Dale's ship is set up, there is no "scooping" effect of the ram air to force it through the heat muff which is stuffed with springs or something to increase the surface area that the air can whip around as it warms up. Without the scoop, it is only a suction effort of the motor to get air through the muff. This suction effort, therfore, can suck through any other leaks and cracks in the system, diluting the heating effect of what comes through the muff. I believe that there should be positive, above ambient pressure in the airbox whether the heat is on or off. This can only come with some attempt at ram effect which exists with every small factory ship I can think of, most taking the air pressure from the upper, pressurised plenum of the pressure cowl. Look at the SIZE muff of what a Piper Cub or Taylorcraft has and use it as a guide. I also recommend a review of carb ice at William Wynne's Corvair site as he and Grace are now the authority on this subject since his accident. Call the hangar and talk to Grace, she will get all the answers. The website is www.flycorvair.com/carbice.html Read this all the way through noting the comments in the final paragraphs. The current FAA approved operating manual, Form X30012, for the A, C and O-200 series from Continental reads, "The correct way to use carburetor heat is to first apply full heat to remove any ice that has formed. Determine the minimum amount of heat required to prevent ice forming, each time removing any ice that has formed by applying full heat." It also states to use heat full on during all ground operations as ice easily forms on the ground with the engine idling with dire results upon takeoff. The carb heat should be on full "until the throttle is advanced for the take-off run" which is when cold air is selected.... FAR 23.1093, advisory to us homebuilders, reads: Sec. 23.1093 Induction system icing protection. (a) Reciprocating engines. Each reciprocating engine air induction system must have means to prevent and eliminate icing. Unless this is done by other means, it must be shown that, in air free of visible moisture at a temperature of 30=B0 F.-- (1) Each airplane with sea level engines using conventional venturi carburetors has a preheater that can provide a heat rise of 90=B0 F. with the engines at 75 percent of maximum continuous power; The preceding applies to our carburated ships Some irrelevent stuff omitted in this spot (4) Each airplane with a sea level engine(s) using a fuel metering device tending to prevent icing has a sheltered alternate source of air with a preheat of not less than 60=B0F with the engines at 75 percent of maximum continuous power; The preceding would apply to an Aerocarb or Ellsion equipped injected ship (5) Each airplane with sea level or altitude engine(s) using fuel injection systems having metering component on which impact ice may accumulate has a preheater capable of providing a heat rise of 75=B0 F. with the engine is operating at 75 percent of its maximum continuous power; and (6) Each airplane with sea level or altitude engine(s) using fuel injection systems not having fuel metering components projecting into the airstream on which ice may form, and introducing fuel into the air induction system downstream of any components or other obstruction on which ice produced by fuel evaporation may form, has a sheltered alternate source of air with a preheat of not less than 60=B0F with the engines at 75 percent of maximum continuous power. The preceding applies to fuel injected ships It appears that you would need a 90 degree rise on a a 30 degree day. Unfortunately, they just tell what you need to have rather than the means to get there. I am amazed that Bingelis is silent as well. How can he write abook called Firewall Forward and not talk of such a value or goal to design to? It has to be in there but I must not be seeing it. Flitzer los! Chris ________________________________ Message 16 ____________________________________ Time: 12:56:14 PM PST US Subject: RE: Pietenpol-List: flight testing Greg/Dale's plane From: "Textor, Jack" --> Pietenpol-List message posted by: "Textor, Jack" All, Has anyone constructed a Piet with a "flying tail"? In my model days I built several Sig Cadet Seniors. A great trainer, high wing, lot's of dihedral, 80" wings. After the first one I built some airfoil into the horizontal stabalizer and converted to conventional gear. It really improved the flight characteristics. Jack Textor Des Moines ________________________________ Message 17 ____________________________________ Time: 01:20:46 PM PST US From: "John E. Joyce" Subject: RE: Pietenpol-List: Tailwheel control schemes Hi Rick: Would like to see the pick of the tailwheel modification but get only a thumbnail when trying to open with Windows XP and MS Picture It. A repost would be appreciated. Thanks. John Joyce 9 Sylvia Road North Reading, MA 01864 978.664.3578 -----Original Message----- From: owner-pietenpol-list-server@matronics.com [mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Rick Holland Subject: Pietenpol-List: Tailwheel control schemes After reading many archive messages about tailwheel control setup it appears that many people have seen a need to make the tailwheel control less sensitive than the rudder control. I am assuming I will want this also so I figure its easier to build it in now that later. Have seen many ingenious methods to do this but the 'Hanging two tubes off the bellcrank tube' method in the attached photo seems to be the cleanest I have found so far. And by placing multiple tabs or holes in the hanging tubes the sensitivity can be easily changed. (Sorry I don't know the name of the builder to give him credit). Opinions? -- Rick Holland Castle Rock, CO (Density altitude up to 8356 ft. currently, and its not even hot yet!) ________________________________ Message 18 ____________________________________ Time: 03:55:41 PM PST US From: Isablcorky@AOL.COM Subject: Pietenpol-List: Urbana Pieters Are any you list regulars making plans to attend the SAA weekend, June 10, 11 12 at Urbana, Ill? It is not an advertised event. Membership is priced on voluntary contributions. Of course you have to pay for the meals being served. Should be a nice experience. Paul is trying to make SAA what EAA was about 55to 60. We are thinking about it but can't plan that far ahead. Corky and Isabelle ________________________________ Message 19 ____________________________________ Time: 04:34:31 PM PST US s=s1024; d=yahoo.com; b=C1PBRZCHq45SmJbwzk2NgMOaErdQncmy9GCbrllv2df2VZD1CtSFkS+CCwfRAgDo7b6nc3zOi2fTBZdOia7fSnc3A6LOeju1qGRIAVpNryngeX36Jsp0dWKpMWBU/LvtxiMrg6cjVhV3K0iDOeEjeG0WNd617VPmIybKEpyHvcI= ; From: Larry Nelson Subject: Re: Pietenpol-List: Urbana --> Pietenpol-List message posted by: Larry Nelson If the WX allows me to fly, I will be there in Bonanza V-35B N2980A, camping by my plane. Pietenpol N444MH will have to stay home. --- Isablcorky@aol.com wrote: > Pieters > > Are any you list regulars making plans to attend the > SAA weekend, June 10, > 11 12 at Urbana, Ill? It is not an advertised event. > Membership is priced on > voluntary contributions. Of course you have to pay > for the meals being served. > Should be a nice experience. Paul is trying to make > SAA what EAA was about > 55to 60. We are thinking about it but can't plan > that far ahead. > > Corky and Isabelle > Larry Nelson Springfield, MO Beechcraft Bonanza V-35B N2980A Pietenpol Air Camper N444MH 1963 GMC 4106-1618 SV/ Spirit of America ARS WB0JOT ________________________________ Message 20 ____________________________________ Time: 05:36:59 PM PST US From: "Lynn Knoll" Subject: Pietenpol-List: Grove Wheels/Brakes It's shopping time for wheels, brakes, tires, & master cylinders and there is a large price savings with Grove's. What advice can you all give? ________________________________ Message 21 ____________________________________ Time: 05:39:35 PM PST US s=s1024; d=yahoo.com; b=4hMQn6C9n0vhs0hK5xPjINHJgSfqtejf5BKpFk7sU4EevohvwGKtRyisxk+Q1MzsJ8U6e1HC798ZdmyR+RBjwPI98HaY2WUC8S5MHMlY2Z1Y7+EkDK2qrohBF4KBaRL19iU9SK+hgNv9FYviKy7LE78ISGg6IQaeCbvk4CvspXQ= ; From: Galen Hutcheson Subject: Re: Pietenpol-List: dihedral --> Pietenpol-List message posted by: Galen Hutcheson Half gallon milk jugs work great! Make sure the bottom of the bottle is pointed downward (or put the plane in a dive) to prevent having to fly around until your pants dry. :) Doc --- Michael D Cuy wrote: > --> Pietenpol-List message posted by: Michael D Cuy > > > sure makes it easier to pee in a bottle by steering > with your feet while > your hands > are busy. Beats stopping for fuel when you don't > have to on an x-country > and wasting 45 minutes:) > > Mike C. > > > > > > > browse > Subscriptions page, > FAQ, > > > > > > > > > > ________________________________ Message 22 ____________________________________ Time: 06:49:55 PM PST US d="scan'208,217"; a="981089871:sNHT30629186" From: "Christian Bobka" Subject: Re: Pietenpol-List: Urbana Corky, I went two years ago. Might make it depending on what the airline wants to do with me. Chris Braumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message ----- From: Isablcorky@aol.com To: pietenpol-list@matronics.com Sent: Wednesday, June 01, 2005 5:54 PM Subject: Pietenpol-List: Urbana Pieters Are any you list regulars making plans to attend the SAA weekend, June 10, 11 12 at Urbana, Ill? It is not an advertised event. Membership is priced on voluntary contributions. Of course you have to pay for the meals being served. Should be a nice experience. Paul is trying to make SAA what EAA was about 55to 60. We are thinking about it but can't plan that far ahead. Corky and Isabelle ________________________________ Message 23 ____________________________________ Time: 09:13:24 PM PST US From: Rcaprd@aol.com Subject: Re: Pietenpol-List: Cork float fuel-proof varnish? In a message dated 6/1/2005 2:15:40 PM Central Standard Time, steve@wotelectronics.com writes: I am replacing the cub-style fuel guage rod in my plane, and would like to re-coat the cork while I have it out. There are a few chips in the existing varnish, and I want to make sure it doesn't start absorbing fuel and sink in-flight, as I've been told this can happen. Steve, I built both my tanks using fiberglass and Polyester Resin (auto body stuff). Problem is that any alcohol in the fuel could soften up the resin. For this reason, I coated my float with polyester resin to fuel proof it, as well as use it as a monitor for any softening effect of accidental alcohol in the fuel. Chuck G. ________________________________ Message 24 ____________________________________ Time: 10:51:47 PM PST US From: Rcaprd@aol.com Subject: Re: Pietenpol-List: Second Pilot report Chris, You have posted some very informative info for all to see !! Just a little note: you said - This had the effect of increasing the attack angle of the stabiliser making it more agressive in holding the nose up. To be specific, the angle of incidence is the angle between the Mean Aerodynamic Chord of the airfoil and the longitude line, or 'Thrust Line' of the airframe. Thus, lowering the leading edge of the stabilizer, Decreases the angle of Incidence of the stab. This also decreases the angle of attack of the stab, thus pushing down on the tail - thus Increasing the Angle of Attack of the Wing. Angle of Attack is the angle between the MAC and the Relative Wind. 2000 rpm cruise is a pretty good range, and is the same as on my plane. A difference in just 100 rpm effects pitch attitude for reasons you stated. This is a typical Pietenpol Characteristic. Some of these things you just have to accept as design characteristics, such as the Straight Wing as opposed to Dihedral. I prefer straight wing, as designed. Neutral Thrust Glide sounds like you have most of the wing heavy, and pitch problems worked out. Right Rudder in cruise is due to torque, and if you adjust it out by shimming the engine mount, it will probably show up in another way. Nothing is free. I just rest my right foot on the rudder bar, and live with it. Hardly noticeable in cruise, until I lift my foot off the rudder bar, causing a left yaw. you said - She has so much drag on final that pulling the power to idle and pointing agressively down will give a good rate of descent at a constant airspeed so slips to landing should not be often necessary. This is true, but it's a good thing to practice, to prepare for squeezing into a very short landing field, in case of an emergency. If the engine mount was long enough to get rid of that 60 lbs of ballast, the ship will handle MUCH better !! Chuck Gantzer NX770CG ________________________________ Message 25 ____________________________________ Time: 11:16:07 PM PST US d="scan'208,217"; a="342106960:sNHT1228576680" From: "Christian Bobka" "Paul Shenton" Subject: Pietenpol-List: We mean the same thing Chuck, We are both trying to say the same thing. If you are the stab and you were having a good day and were talking to the engineer who was designing you, you might suggest to him that he use an airfoil shape and have the airfoil inverted as it would then have the greatest effect. The stab holds the nose up by it providing lift DOWN. Just as I increase the angle of attack of the big wing by raising its leading edge, I increase the angle of attack of the stabilizer by lowering its leading edge. Look at an old Fleet and you will see exactly what not to do. Look at a handful of Waco Model 10s that were lucky enough to come with an airfoil shaped stab and you will see exactly what to do. Formal definitions aside, this is was it going on with all the lifties....and now Oscar has a grasp on a concept new to him. As for the 60 pounds of ballast, Greg and I plan a reweigh so that we can determine a couple of things not done the first time around (when I was not there although Greg is a big proponent of this). We will run ship level tail up weight numbers with occupants in one then both cockpits in order to determine the true CG of each seat with a live person in the seat(s) rather than estimating the position of the CG of each occupant. This should dial in some really good numbers to make sure we are not penalising ourselves by assuming a too far aft position of the occupant's own CG. Likewise, we will run weight numbers with the aircraft in a taildown position with one then both seats occupied by the same "dummies" and, after noting the angle the ship sits at, we can run a little math that will enable us to determine the true vertical CG of the ship. This final exercise is all to widen the knowledge base of the user group. Cheers, Chris, Chris Braumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message ----- From: Rcaprd@aol.com To: pietenpol-list@matronics.com Sent: Thursday, June 02, 2005 12:51 AM Subject: Re: Pietenpol-List: Second Pilot report Chris, You have posted some very informative info for all to see !! Just a little note: you said - This had the effect of increasing the attack angle of the stabiliser making it more agressive in holding the nose up. To be specific, the angle of incidence is the angle between the Mean Aerodynamic Chord of the airfoil and the longitude line, or 'Thrust Line' of the airframe. Thus, lowering the leading edge of the stabilizer, Decreases the angle of Incidence of the stab. This also decreases the angle of attack of the stab, thus pushing down on the tail - thus Increasing the Angle of Attack of the Wing. Angle of Attack is the angle between the MAC and the Relative Wind. 2000 rpm cruise is a pretty good range, and is the same as on my plane. A difference in just 100 rpm effects pitch attitude for reasons you stated. This is a typical Pietenpol Characteristic. Some of these things you just have to accept as design characteristics, such as the Straight Wing as opposed to Dihedral. I prefer straight wing, as designed. Neutral Thrust Glide sounds like you have most of the wing heavy, and pitch problems worked out. Right Rudder in cruise is due to torque, and if you adjust it out by shimming the engine mount, it will probably show up in another way. Nothing is free. I just rest my right foot on the rudder bar, and live with it. Hardly noticeable in cruise, until I lift my foot off the rudder bar, causing a left yaw. you said - She has so much drag on final that pulling the power to idle and pointing agressively down will give a good rate of descent at a constant airspeed so slips to landing should not be often necessary. This is true, but it's a good thing to practice, to prepare for squeezing into a very short landing field, in case of an emergency. If the engine mount was long enough to get rid of that 60 lbs of ballast, the ship will handle MUCH better !! Chuck Gantzer NX770CG