Original Posted By:
I just got back and have been wading through several days worth of posts. Interestingto note the comments about the stab incidence and various "fixes" as wellas the standard aerodynamics 101 explanations. I noticed as a kid that some old, slow free-flight models, especially the oneswith undercambered airfoils had LIFTING stabs. Sort of goes against what we claimto be gospel in today's world. The reasoning was that with CG could be movedfurther aft and not be burdened by stalls, snap-rolls and possible resultingspins. So, how might this apply to our Piets? They are slow and have an ubdercamberedwing also.Take a look at inflight photos of Piets and notice that many of them have a droopingelevator! I know mine does and I have seen some others in the Brodhead patternthat do also.One other extreme example is the Bleriot Monoplane that has an undercambered stab.Let's not be too hasty in having new builders camber their stabs either on topor on the bottom. Remember all this website does is exchange ideas and, even thoughthey might sound logical, it's not the poster that has his butt on the linewhen it's time to go.......Larry________________________________________________________________________________
Pietenpol-List: Stabilizer incidence
Re: Pietenpol-List: Stabilizer incidence
Original Posted By: LAWRENCE WILLIAMS
Welcome back, Larry.The suggestion is not to build in any stabilizer incidence. Just build in away to adjust the incidence later if needed. Simple to do by adding shims aboveand belowthe stabilizer. You would then be free to rearrange the shims withoutaffecting the fin location. If the fin remains in the same location then therudder hinges won't be affected.Greg Cardinal ----- Original Message -----
Welcome back, Larry.The suggestion is not to build in any stabilizer incidence. Just build in away to adjust the incidence later if needed. Simple to do by adding shims aboveand belowthe stabilizer. You would then be free to rearrange the shims withoutaffecting the fin location. If the fin remains in the same location then therudder hinges won't be affected.Greg Cardinal ----- Original Message -----
Pietenpol-List: Stabilizer incidence
Original Posted By: Rick Holland
Re: Pietenpol-List: Stabilizer incidence
Original Posted By: lshutks(at)webtv.net (Leon Stefan)
Subject: Re: Pietenpol-List: Stabilizer incidenceIn a message dated 6/5/2005 2:56:37 PM Central Standard Time, lnawms(at)msn.com writes:Take a look at inflight photos of Piets and notice that many of them have a drooping elevator! I know mine does and I have seen some others in the Brodheadpattern that do also.Hi Larry !! Good to hear from you. My plane fly's straight level flight, with the elevator (flippers) slightly low. I noticed this same thing in one of the pictures that Corky sentme of his first plane (NX41CC) in flight. I can turn around and watch, and if I pull back on the stick to make the flippers in line with the stab, it pitches up to a very nose up attitude. This is kind of baffling. It's one of the reasons I installed trim tabs on the flippers, and took ALL the negative incidenceout of the stab. I think the weight of the flippers being behind the hinge (no mass balance) is at least some of the reason for it. It still fly's straight & level with the drooping flippers, though. It's in trim at 1850 to 1900rpm indicated, but my tach reads 100 rpm to low, compared to an electronic handheld tach. If I add 100 rpm she climbs, and if I pull 100 rpm out, she descends and picks up speed. Those early planes, like the Bleriot Monoplane, are the only planes I know of with an undercambered stabilizer. It seems they carry a portion of theweight with the stab, so the C of G can be farther aft and it would also be much more induced drag than later designs. Just think what would happen if thestab would stall...the nose will pitch up abruptly past the Critical Angle of Attack, and stall the main wing.Chuck G.It was an absolutely beautiful evening to fly. Clear blue sky, light south wind, mid 80's. I did the River Run, then over an hour of slow flight at about50 mph, with the power pulled back to 1700 rpm indicated, then did a Smokin' Fly By at Beech Field. It's amazing how just put put putting around the sky can clear all the cob webs out of my brain !! ________________________________________________________________________________ ETAuAhUAp5+Mo+97d6IDyo3sh2B2JezqONUCFQC3shLAbPXw9zEo2sX9sVOjie1RSA==
Subject: Re: Pietenpol-List: Stabilizer incidenceIn a message dated 6/5/2005 2:56:37 PM Central Standard Time, lnawms(at)msn.com writes:Take a look at inflight photos of Piets and notice that many of them have a drooping elevator! I know mine does and I have seen some others in the Brodheadpattern that do also.Hi Larry !! Good to hear from you. My plane fly's straight level flight, with the elevator (flippers) slightly low. I noticed this same thing in one of the pictures that Corky sentme of his first plane (NX41CC) in flight. I can turn around and watch, and if I pull back on the stick to make the flippers in line with the stab, it pitches up to a very nose up attitude. This is kind of baffling. It's one of the reasons I installed trim tabs on the flippers, and took ALL the negative incidenceout of the stab. I think the weight of the flippers being behind the hinge (no mass balance) is at least some of the reason for it. It still fly's straight & level with the drooping flippers, though. It's in trim at 1850 to 1900rpm indicated, but my tach reads 100 rpm to low, compared to an electronic handheld tach. If I add 100 rpm she climbs, and if I pull 100 rpm out, she descends and picks up speed. Those early planes, like the Bleriot Monoplane, are the only planes I know of with an undercambered stabilizer. It seems they carry a portion of theweight with the stab, so the C of G can be farther aft and it would also be much more induced drag than later designs. Just think what would happen if thestab would stall...the nose will pitch up abruptly past the Critical Angle of Attack, and stall the main wing.Chuck G.It was an absolutely beautiful evening to fly. Clear blue sky, light south wind, mid 80's. I did the River Run, then over an hour of slow flight at about50 mph, with the power pulled back to 1700 rpm indicated, then did a Smokin' Fly By at Beech Field. It's amazing how just put put putting around the sky can clear all the cob webs out of my brain !! ________________________________________________________________________________ ETAuAhUAp5+Mo+97d6IDyo3sh2B2JezqONUCFQC3shLAbPXw9zEo2sX9sVOjie1RSA==
Re: Pietenpol-List: Stabilizer incidence
Original Posted By: Rcaprd(at)aol.com
I'd expect just about every Piete that is being flown at or near the back edgeof acceptable CG limits (about 20" aft of LE wing) would need to have a littlelift developed by the horizonal stab and the elevator. Drooping elevator wouldchange the "airfoil" shape of the combo H.stab/elevator, therefore developlift, and lots of unnecessary drag. No lift coming from tail plane, nose pitchesup because of where the weight is vs the center of lift on the wing. Puttingincidence in H.stab, would only make permanent the drag. Still think thebest move is to have normally loaded CG somewhere more forward, ca. 16". Allowingfor fat pilots like me to shift the CG back to close to aft limit, when needed,but only when needed. The only way to move "normally loaded", CG forwardis to put weight out in the engine area, much forward of the empty CG, thusminimal additional drag, ie. a battery or a chuck of lead attached to the enginemounts. OR move the wing further back during the building process.Gordon Bowen ----- Original Message -----
I'd expect just about every Piete that is being flown at or near the back edgeof acceptable CG limits (about 20" aft of LE wing) would need to have a littlelift developed by the horizonal stab and the elevator. Drooping elevator wouldchange the "airfoil" shape of the combo H.stab/elevator, therefore developlift, and lots of unnecessary drag. No lift coming from tail plane, nose pitchesup because of where the weight is vs the center of lift on the wing. Puttingincidence in H.stab, would only make permanent the drag. Still think thebest move is to have normally loaded CG somewhere more forward, ca. 16". Allowingfor fat pilots like me to shift the CG back to close to aft limit, when needed,but only when needed. The only way to move "normally loaded", CG forwardis to put weight out in the engine area, much forward of the empty CG, thusminimal additional drag, ie. a battery or a chuck of lead attached to the enginemounts. OR move the wing further back during the building process.Gordon Bowen ----- Original Message -----
Re: Pietenpol-List: Stabilizer incidence
Original Posted By: "Dick Navratil"
Subject: Re: Pietenpol-List: Stabilizer incidencePieters, Back in the sixtys I built a casssutt and had a lot of forward stick pressure on the first flight and I am sure I raised the leading edge to correct it. Now that was forty years ago but I am sure this is what I did. Now this is a mid wing and I am sure I set the hort. streight with the thrust line. Ken Conrad in hot iowa________________________________________________________________________________
Subject: Re: Pietenpol-List: Stabilizer incidencePieters, Back in the sixtys I built a casssutt and had a lot of forward stick pressure on the first flight and I am sure I raised the leading edge to correct it. Now that was forty years ago but I am sure this is what I did. Now this is a mid wing and I am sure I set the hort. streight with the thrust line. Ken Conrad in hot iowa________________________________________________________________________________
Re: Pietenpol-List: Stabilizer incidence
Original Posted By: Clif Dawson
Subject: Re: Pietenpol-List: Stabilizer incidenceIn a message dated 6/6/2005 8:58:40 AM Central Standard Time, jim_markle(at)mindspring.com writes:Maybe mounting your new camera setup pointing aft would tell some interesting tales.....I plan on doing a little flying with a camera pointed outboard along the ailerons so I can get an idea about deflection, etc....Maybe some video of your tail (your AIRPLANE'S tail, that is...) would answer some questions...JMHey Jim, great idea !! I have video pointing aft, from both sides of the cockpit, watching the smoke trail. Ya can't really see the position of the flippers very well, because of the angle of the camera, but it does appear to beslightly down, and I didn't note how much fuel was onboard when I did those flights. I will do several more flights, paying particular attention to the camera angle, and fuel onbd / C.G. location. One thing I've learned from all theseflights with the video camera mounted, is that in normal bumps of turbulence, the camera exaggerates the movements. Quite often, it looks like I'm bouncing all over the place...on second thought, maybe I am, and I'm just usedto it. It's very challenging to shoot good video while flying the plane trying to keep the subject in the viewfinder. I have to slip & skid circling a target, causing the ball to bounce back & fourth (the one on the panel). I have some really great video of three hot air balloons landing, and deflating. I circledthem for about 15 minutes during their operation, with the camera pointing out the left side. I still have to do a flight with the camera pointing directly at the instrument panel. I'm splicing and editing all this video, togive the impression of many cameras mounted on the airframe. I'm really learning alot, about what it takes to get good in flight video. It's looking pretty good, but I've been having problems with the video editing program (Pinnacle Studio 9). I've been in contact with them, and I have to un-install, and re-install it. That's a scary thought, because I don't want to loose any of themany hours of video I have on the computer. I still haven't got any of the video'sto a finished point yet, but I do some stuff to them almost every day. They're all looking pretty good, though...if I can just get this editing programto do the stuff I tell it to do !!Chuck G.NX770CG________________________________________________________________________________Date: Mon, 06 Jun 2005 23:55:14 -0700
Subject: Re: Pietenpol-List: Stabilizer incidenceIn a message dated 6/6/2005 8:58:40 AM Central Standard Time, jim_markle(at)mindspring.com writes:Maybe mounting your new camera setup pointing aft would tell some interesting tales.....I plan on doing a little flying with a camera pointed outboard along the ailerons so I can get an idea about deflection, etc....Maybe some video of your tail (your AIRPLANE'S tail, that is...) would answer some questions...JMHey Jim, great idea !! I have video pointing aft, from both sides of the cockpit, watching the smoke trail. Ya can't really see the position of the flippers very well, because of the angle of the camera, but it does appear to beslightly down, and I didn't note how much fuel was onboard when I did those flights. I will do several more flights, paying particular attention to the camera angle, and fuel onbd / C.G. location. One thing I've learned from all theseflights with the video camera mounted, is that in normal bumps of turbulence, the camera exaggerates the movements. Quite often, it looks like I'm bouncing all over the place...on second thought, maybe I am, and I'm just usedto it. It's very challenging to shoot good video while flying the plane trying to keep the subject in the viewfinder. I have to slip & skid circling a target, causing the ball to bounce back & fourth (the one on the panel). I have some really great video of three hot air balloons landing, and deflating. I circledthem for about 15 minutes during their operation, with the camera pointing out the left side. I still have to do a flight with the camera pointing directly at the instrument panel. I'm splicing and editing all this video, togive the impression of many cameras mounted on the airframe. I'm really learning alot, about what it takes to get good in flight video. It's looking pretty good, but I've been having problems with the video editing program (Pinnacle Studio 9). I've been in contact with them, and I have to un-install, and re-install it. That's a scary thought, because I don't want to loose any of themany hours of video I have on the computer. I still haven't got any of the video'sto a finished point yet, but I do some stuff to them almost every day. They're all looking pretty good, though...if I can just get this editing programto do the stuff I tell it to do !!Chuck G.NX770CG________________________________________________________________________________Date: Mon, 06 Jun 2005 23:55:14 -0700
Re: Pietenpol-List: Stabilizer incidence
Original Posted By: Clif Dawson
You might try a couple Mylar strips (old cassette???
attached to thewing T.E. to show how much of a "downwash" you're getting from the wing --if they are just long enough to just miss the Stab. L.E. you'll have an ideawhat angle of attack it's working at. Roll them up & tape them to thecenter section till you get to the "Test Area".Mike C. (I'm not a test engineer, but I've played one at work! ;-)Pretty Prairie, KS ----- Original Message -----
You might try a couple Mylar strips (old cassette???
attached to thewing T.E. to show how much of a "downwash" you're getting from the wing --if they are just long enough to just miss the Stab. L.E. you'll have an ideawhat angle of attack it's working at. Roll them up & tape them to thecenter section till you get to the "Test Area".Mike C. (I'm not a test engineer, but I've played one at work! ;-)Pretty Prairie, KS ----- Original Message -----Re: Pietenpol-List: Stabilizer incidence
Original Posted By: Rcaprd(at)aol.com
Subject: Re: Pietenpol-List: Stabilizer incidenceHey !!You guys are coming up with some great ideas !! Cassette tapes...I still have some old 8 track tapes !! I'll be back up in the Test Bed at the end ofthe week, after this next front goes through. I don't have any lab coats, or pocket protectors...I wear old tee shirts, and make notes on my hand...that waymy notes can't blow away !!Chuck G.________________________________________________________________________________
Subject: Re: Pietenpol-List: Stabilizer incidenceHey !!You guys are coming up with some great ideas !! Cassette tapes...I still have some old 8 track tapes !! I'll be back up in the Test Bed at the end ofthe week, after this next front goes through. I don't have any lab coats, or pocket protectors...I wear old tee shirts, and make notes on my hand...that waymy notes can't blow away !!Chuck G.________________________________________________________________________________
Re: Pietenpol-List: Stabilizer incidence
Original Posted By: LAWRENCE WILLIAMS
Larry,Good to here from you.You wrote:Take a look at inflight photos of Piets and notice that many of them have a droopingelevator! I know mine does and I have seen some others in the Brodhead patternthat do alsoThe reason for the drooped elevator on the Piet is that it weighs something andgravity pulls down on it. You could call it "gravitational" trimming. If theelevator control system had a counterweight in it that counterbalanced the weightof the elevators, the droop would not exist and the ship would fly withmore noseup tendency.To put it another way, if you flew your ship inverted, the elevator would stilldroop.The Sleek Streak that I still have from 40 years ago shows a distinct leading edgelow position for the horizontal stab. I do not think that it is a liftingstab.See a classic book called "Aero Science of Free Flight" by Charles Hampson Grant available for about 10 bucks on ebay or www.bookfinder.com for discussion of lifting stabs and an otherwise unsurpassed discussion on empirically determining flight characteristics.You wrote:One other extreme example is the Bleriot Monoplane that has an undercambered stab.Early designers had erroneously assumed that both surfaces lifted. That was myelusion to the early Fleet biplanes having the camber on the top of the stabiliserin one of the flight reports. A handful of Waco Model 10s, mostly thosedestined for seaplane use, used in inverted camber airfoil on the stab to increaseeffectiveness.ChrisBraumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message -----
Larry,Good to here from you.You wrote:Take a look at inflight photos of Piets and notice that many of them have a droopingelevator! I know mine does and I have seen some others in the Brodhead patternthat do alsoThe reason for the drooped elevator on the Piet is that it weighs something andgravity pulls down on it. You could call it "gravitational" trimming. If theelevator control system had a counterweight in it that counterbalanced the weightof the elevators, the droop would not exist and the ship would fly withmore noseup tendency.To put it another way, if you flew your ship inverted, the elevator would stilldroop.The Sleek Streak that I still have from 40 years ago shows a distinct leading edgelow position for the horizontal stab. I do not think that it is a liftingstab.See a classic book called "Aero Science of Free Flight" by Charles Hampson Grant available for about 10 bucks on ebay or www.bookfinder.com for discussion of lifting stabs and an otherwise unsurpassed discussion on empirically determining flight characteristics.You wrote:One other extreme example is the Bleriot Monoplane that has an undercambered stab.Early designers had erroneously assumed that both surfaces lifted. That was myelusion to the early Fleet biplanes having the camber on the top of the stabiliserin one of the flight reports. A handful of Waco Model 10s, mostly thosedestined for seaplane use, used in inverted camber airfoil on the stab to increaseeffectiveness.ChrisBraumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message -----
Re: Pietenpol-List: Stabilizer incidence
Original Posted By: Rcaprd(at)aol.com
Here are two images of the Fleet Model 2 showing the horizontal stab with the camberon the top! It would have performed beter if they had flipped it over!Also note the different incidence angles of the wings in the photo which does notappear in the drawing. This could be an error in repair of the fuselage atsme point or it could be the way it really was....ChrisBraumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message -----
Here are two images of the Fleet Model 2 showing the horizontal stab with the camberon the top! It would have performed beter if they had flipped it over!Also note the different incidence angles of the wings in the photo which does notappear in the drawing. This could be an error in repair of the fuselage atsme point or it could be the way it really was....ChrisBraumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message -----
Re: Pietenpol-List: Stabilizer incidence
Original Posted By: Gordon Bowen
Do not confuse center of lift with pitching moment.....ChrisBraumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message -----
Do not confuse center of lift with pitching moment.....ChrisBraumeister und Inspektor der Flitzer und Flitzermotoren ----- Original Message -----
Re: Pietenpol-List: Stabilizer incidence
Original Posted By: "walt evans"