Original Posted By: owner-pietenpol-list-server(at)matronics.com
TerryWilliam Wynne also had a bad crash in his Pietenpol. He speaks fromexperience and true desire to keep us safe. I know I am listening.>From http://www.flycorvair.com/carbice.html"William Wynne was the passenger in his Corvair powered Pietenpol when itcrashed north of Tampa, Florida, on July 14, 2001. The engine cut off at700' AGL, which gave only 60 seconds to attempt a restart and execute aforced landing. To avoid people on the ground, the pilot tried a sharp bankand the plane spun in from 80'. The impact destroyed the airframe. When freeing the trapped pilot, a fire started and ignited William'sfuel-soaked clothes. While extensively burned, both William and the pilotsurvived the accident. An investigation into the engine stoppage hasindicated that carb ice almost certainly was the cause. Because a few ofthe engine components were incinerated in the fire, no one will ever be ableto say with 100% certainty that carb ice was the cause. The engine wasrecovered from a wrecking yard where it sat for months, placed on a teststand, and runs well. The remaining wreckage was examined very closely andno evidence of any kind of failure was found. "His advice on what design element was wrong is here.http://flycorvair.net/2013/12/19/pieten ... rt-2/Chris T.Sacramento, CaWestcoastpiet.com-----Original Message-----
RE: Pietenpol-List: Re: Speaking of outdated stuff? Center section fuel
RE: Pietenpol-List: Re: Speaking of outdated stuff? Center section fuel
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Terry, you can see the effects of what you are asking using the spreadsheetI posted yesterday. If you just swap the values for the fuel tank and thebaggage compartment for my airplane (the data that I sent in thespreadsheet) you can see pretty closely what the effects would be, if itwere my airplane.I just did that - swapping the 90 lbs of fuel from the centersection tank tothe baggage compartment, and taking the fuel tank weight to 0.00. With 90lbs (15 gallons) of fuel in the nose, the CG with my 195 lb butt in the rearseat would move from 19.94" to 17.71" aft of the leading edge. Very Nice!However, when you are down to 2.5 gallons of fuel (15 lbs) the CG goes backto 19.42" - nearly a 2" shift. I suspect you will need a trim system ofsome sort otherwise you are going to be constantly pushing on the stick tokeep the nose down (f the plane was trimmed to fly straight and level with afull tank). If you are flying near empty and for whatever reason you takeyour hand off the stick, the nose will want to pitch up which could get veryinteresting if you were already flying close to a stall.With the centersection tank, the situation is reversed, but the change isslight. Again, with the data from my airplane, with my 195 lbs of Macho,Pietenpol Aviator sitting comfortably in the rear seat, with 90 lbs of fuelon board and no baggage in the nose, my CG is hovering around the dreaded20" barrier at 19.94" aft of the Leading edge (one reason I generally carryabout 5 lbs of stuff in the baggage compartment). If I burn all but 2.5gallons from my tank, the CG moves to 19.83", or just over a tenth of aninch, and in the direction that if I take my hand off the stick, the nosewill go down, not up.I like my centersection fuel tank. I never have to worry that an extremenoseup attitude might starve the fuel supply, and I have a large enoughbaggage compartment to hold a tent and sleeping bag (a true "Air Camper").The only worry is the possibility of a shifting centersection in a crashcausing fuel leakage. When I recover my airplane (hopefully not for severalmore years) I will put in braided flexible fuel lines. I have had oneforced landing which caused substantial damage to the airframe, includingdragging a wingtip in the ensuing groundloop when the axle broke, withoutcausing any shift of the centersection or damage to the fuel lines. I waslucky. In Kevin Purtee's crash, those on the scene reported a large fuel leak dueto the ruptured fuel tank. There was no fire. Kevin was lucky. There wasnothing left of the fuselage forward of the rear cockpit, so I don't thinkyou could say a nose tank would have fared better.This is one of those decisions in building a Pietenpol that every builderneeds to make for himself, based on facts and information, and how he wantsto build and fly his airplane. There is no right or wrong answer. Just tryto make an informed choice.Jack PhillipsNX899JPSmith Mountain Lake, Virginia-----Original Message-----
Terry, you can see the effects of what you are asking using the spreadsheetI posted yesterday. If you just swap the values for the fuel tank and thebaggage compartment for my airplane (the data that I sent in thespreadsheet) you can see pretty closely what the effects would be, if itwere my airplane.I just did that - swapping the 90 lbs of fuel from the centersection tank tothe baggage compartment, and taking the fuel tank weight to 0.00. With 90lbs (15 gallons) of fuel in the nose, the CG with my 195 lb butt in the rearseat would move from 19.94" to 17.71" aft of the leading edge. Very Nice!However, when you are down to 2.5 gallons of fuel (15 lbs) the CG goes backto 19.42" - nearly a 2" shift. I suspect you will need a trim system ofsome sort otherwise you are going to be constantly pushing on the stick tokeep the nose down (f the plane was trimmed to fly straight and level with afull tank). If you are flying near empty and for whatever reason you takeyour hand off the stick, the nose will want to pitch up which could get veryinteresting if you were already flying close to a stall.With the centersection tank, the situation is reversed, but the change isslight. Again, with the data from my airplane, with my 195 lbs of Macho,Pietenpol Aviator sitting comfortably in the rear seat, with 90 lbs of fuelon board and no baggage in the nose, my CG is hovering around the dreaded20" barrier at 19.94" aft of the Leading edge (one reason I generally carryabout 5 lbs of stuff in the baggage compartment). If I burn all but 2.5gallons from my tank, the CG moves to 19.83", or just over a tenth of aninch, and in the direction that if I take my hand off the stick, the nosewill go down, not up.I like my centersection fuel tank. I never have to worry that an extremenoseup attitude might starve the fuel supply, and I have a large enoughbaggage compartment to hold a tent and sleeping bag (a true "Air Camper").The only worry is the possibility of a shifting centersection in a crashcausing fuel leakage. When I recover my airplane (hopefully not for severalmore years) I will put in braided flexible fuel lines. I have had oneforced landing which caused substantial damage to the airframe, includingdragging a wingtip in the ensuing groundloop when the axle broke, withoutcausing any shift of the centersection or damage to the fuel lines. I waslucky. In Kevin Purtee's crash, those on the scene reported a large fuel leak dueto the ruptured fuel tank. There was no fire. Kevin was lucky. There wasnothing left of the fuselage forward of the rear cockpit, so I don't thinkyou could say a nose tank would have fared better.This is one of those decisions in building a Pietenpol that every builderneeds to make for himself, based on facts and information, and how he wantsto build and fly his airplane. There is no right or wrong answer. Just tryto make an informed choice.Jack PhillipsNX899JPSmith Mountain Lake, Virginia-----Original Message-----
RE: Pietenpol-List: Re: Speaking of outdated stuff? Center section fuel
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Terry, I'm glad you asked that question, as it's been on my mind all day, sinceMike's post. I don't mean this as a rebuttal for what Mike said, only anobservation. I'm not sure if there is a conclusive answer. Certainly, no onecould argue much with Mike's logic...but I have a 16 gallon wing tank. Quitehonestly, I love the process of refueling...even if while perched on aladder and the strut. Who wouldn't? Re-fueling means that you're goingflying again! Maybe not that day, but, again, someday. I enjoy that as muchas I enjoy removing the 84 screws that hold my cowling in place....as muchas I enjoy removing all the panels for annual inspection. It's what I signedup for.As mentioned, my wing tank is 16 gallons. Cabanes are tilted back 4". That'sthe real key...the beauty of setting CG with the wing. There is no worryabout fuel burn. Most aft CG, Most Forward CG, Gross CG, all fall withinlimits. I used Jack's chart. It's great! You can easily plug in hypotheticalnumbers all day and watch the results.Gary BootheNX308MB-----Original Message-----
Terry, I'm glad you asked that question, as it's been on my mind all day, sinceMike's post. I don't mean this as a rebuttal for what Mike said, only anobservation. I'm not sure if there is a conclusive answer. Certainly, no onecould argue much with Mike's logic...but I have a 16 gallon wing tank. Quitehonestly, I love the process of refueling...even if while perched on aladder and the strut. Who wouldn't? Re-fueling means that you're goingflying again! Maybe not that day, but, again, someday. I enjoy that as muchas I enjoy removing the 84 screws that hold my cowling in place....as muchas I enjoy removing all the panels for annual inspection. It's what I signedup for.As mentioned, my wing tank is 16 gallons. Cabanes are tilted back 4". That'sthe real key...the beauty of setting CG with the wing. There is no worryabout fuel burn. Most aft CG, Most Forward CG, Gross CG, all fall withinlimits. I used Jack's chart. It's great! You can easily plug in hypotheticalnumbers all day and watch the results.Gary BootheNX308MB-----Original Message-----
Re: Pietenpol-List: Re: Speaking of outdated stuff? Center section fuel
Original Posted By: Kip and Beth Gardner
Terry, you commented exactly on what was going through my mind as I read Brian's post. No one is advocating using a wing tank and THEN setting up the plane to be out of CG limits, that would be, frankly, stupid. Using a wing tank, just to be clear one more time, eliminates a factor that is always the case with a nose tank - that the CG will shift aft as fuel is consumed. The arguments against a wing tank to some degree fall in the category of what Chuck Gantzer, a former member of this list who flies his Piet literally all over the country, used to call "building for crash-worthiness, not flight-worthiness". There are potential problems with both tank locations. I might mention that many years ago the Pavliga's wing tank on Sky Gypsy split a seam while the elder Frank was flying. He got soaked with gas and by all accounts spent a number of terrifying minutes getting the plane back on the ground. As you, Mike, and William have all said earlier, it's a matter of building well with risk management in mind. (It is possible to build well and still produce a crappy product! - our home is a good example, built like a tank by an expert craftsman, but much less than comfortably livable because of design flaws).Kip GardnerOn Mar 25, 2014, at 9:11 AM, jarheadpilot82 wrote:> >>> Brian,>> I am not getting your logic->> "Your weight has nothing to do with it. You simply don't fly if > there is an aft CG and having the fuel in the wing just makes the > problem worse.">> Fuel in the wing makes it worse? How is that? Fuel in the wing sits > closer to the CG than fuel in the nose, and the burn off affects CG > less, not more the closer it is to the aircraft's CG.>> "Running out of fuel (or nearly running out of fuel) in a nose tank > versus the same in a wing tank (or nearly running out of fuel) > cannot make the situation worse. If the fuel is gone it is gone. The > difference that in a nose tank is that any fuel moves the CG forward > at everything but empty. Since no one can fly on empty it is always > better in the nose than in the wing and the amount of weight added > to the nose, the length of the engine mount or the amount the wing > is moved back is less and on average the cg is more forward. There > is also the 15lbs or more of the tank weight itself that is > helpingthe aft cg problem all they time. The 10 lbs (or whatever you > consider that to be) of reserve fuel that no one ever uses is also > helping. ">> Brian, I am not worried about the fuel that is left in the nose > tank. I am worried about the fuel that burned off that was, at one > time, forward of the CG that was balancing against my fat butt > sitting behind the CG. Once that fuel has burned off, there is less > weight to counteract my fat butt, so the CG moves aft. Check your > aerodynamics and design books. I just don't want to move it so far > aft, that the airplane is aft of the safe aft CG. That can be > mitigated in the construction phase by adjustment of the wing > location, and all I am saying is that that issue should be dealt > with in the build. Nobody should fly an airplane outside of the CG > range. Will the airplane fly? Yes. Are your options lessened when > you do? Absolutely.>> "If you weigh more and it is your airplane then it is more important > that the fuel is forward.">> It is most important that the CG is balanced, and the aircraft is > flown in the proper CG range.>> --------> Semper Fi,>> Terry Hand> Athens, GA>> USMC, USMCR, ATP> BVD DVD PDQ BBQ>>> Read this topic online here:>> http://forums.matronics.com/viewtopic.p ... __________
Terry, you commented exactly on what was going through my mind as I read Brian's post. No one is advocating using a wing tank and THEN setting up the plane to be out of CG limits, that would be, frankly, stupid. Using a wing tank, just to be clear one more time, eliminates a factor that is always the case with a nose tank - that the CG will shift aft as fuel is consumed. The arguments against a wing tank to some degree fall in the category of what Chuck Gantzer, a former member of this list who flies his Piet literally all over the country, used to call "building for crash-worthiness, not flight-worthiness". There are potential problems with both tank locations. I might mention that many years ago the Pavliga's wing tank on Sky Gypsy split a seam while the elder Frank was flying. He got soaked with gas and by all accounts spent a number of terrifying minutes getting the plane back on the ground. As you, Mike, and William have all said earlier, it's a matter of building well with risk management in mind. (It is possible to build well and still produce a crappy product! - our home is a good example, built like a tank by an expert craftsman, but much less than comfortably livable because of design flaws).Kip GardnerOn Mar 25, 2014, at 9:11 AM, jarheadpilot82 wrote:> >>> Brian,>> I am not getting your logic->> "Your weight has nothing to do with it. You simply don't fly if > there is an aft CG and having the fuel in the wing just makes the > problem worse.">> Fuel in the wing makes it worse? How is that? Fuel in the wing sits > closer to the CG than fuel in the nose, and the burn off affects CG > less, not more the closer it is to the aircraft's CG.>> "Running out of fuel (or nearly running out of fuel) in a nose tank > versus the same in a wing tank (or nearly running out of fuel) > cannot make the situation worse. If the fuel is gone it is gone. The > difference that in a nose tank is that any fuel moves the CG forward > at everything but empty. Since no one can fly on empty it is always > better in the nose than in the wing and the amount of weight added > to the nose, the length of the engine mount or the amount the wing > is moved back is less and on average the cg is more forward. There > is also the 15lbs or more of the tank weight itself that is > helpingthe aft cg problem all they time. The 10 lbs (or whatever you > consider that to be) of reserve fuel that no one ever uses is also > helping. ">> Brian, I am not worried about the fuel that is left in the nose > tank. I am worried about the fuel that burned off that was, at one > time, forward of the CG that was balancing against my fat butt > sitting behind the CG. Once that fuel has burned off, there is less > weight to counteract my fat butt, so the CG moves aft. Check your > aerodynamics and design books. I just don't want to move it so far > aft, that the airplane is aft of the safe aft CG. That can be > mitigated in the construction phase by adjustment of the wing > location, and all I am saying is that that issue should be dealt > with in the build. Nobody should fly an airplane outside of the CG > range. Will the airplane fly? Yes. Are your options lessened when > you do? Absolutely.>> "If you weigh more and it is your airplane then it is more important > that the fuel is forward.">> It is most important that the CG is balanced, and the aircraft is > flown in the proper CG range.>> --------> Semper Fi,>> Terry Hand> Athens, GA>> USMC, USMCR, ATP> BVD DVD PDQ BBQ>>> Read this topic online here:>> http://forums.matronics.com/viewtopic.p ... __________
RE: Pietenpol-List: Re: Speaking of outdated stuff? Center section fuel
Original Posted By: owner-pietenpol-list-server(at)matronics.com
OK Tom, You asked for it...I think the drooping elevator is largely a myth. From many angles, theelevator looks like it droops in flight because the reference that the eyehas is the horizontal stabilizer. But the edge of the stabilizer is at anangle to the edge of the elevator, hence the appearance of a droop. Hereare a few pictures from my files of Pietenpols in cruise flight:This shows the difference in angles I was talking about. See the angle ofthe edge of the horizontal stabilizer, compared to the edge of the elevator,which is straight? This is what creates the illusion of tail droop. Youreye tries to make the two edges line up.This one is a picture of Gene Rambo flying his son, Will, in my airplane.In this picture the horizontal tail is just about edge on, so the side ofthe stabilizer doesn't give the impression that the elevator is drooping.Looks pretty straight to meHere's another picture of my plane in flight:Here the angle is different and the side of the stabilizer does make it looklike the elevator is slightly down, but I assure you it's not.Here's Mike Cuy's airplane, photo taken from mine. Note his tail - nodroop.Here's Randy Bush's airplane, photo taken from Ryan Mueller's (now JohnHofmann's) N502R. Notice the tail. Where's the supposed droop?Lastly, this picture shows Kevin Purtee on the left, Shad Bell in thecenter, and me on the right (photo taken by Bill Church during Brodhead2011). You will note that my tail is slightly drooped with respect to theother two. The reason for this is that I was having to push my littleContinental A65 for all it was worth to keep up with those two Corvairpowered Pietenpols, and I had to hold the nose down to maintain my positionin the formation and keep it from climbing at that speed.There may be a slight droop due to downwash from the wing, but other thanthat, I don't think the dreaded tail droop exists at all. Build it to theplans, and build it straight and it should fly just fine.Jack PhillipsNX899JPSmith Mountain Lake, Virginia-----Original Message-----
OK Tom, You asked for it...I think the drooping elevator is largely a myth. From many angles, theelevator looks like it droops in flight because the reference that the eyehas is the horizontal stabilizer. But the edge of the stabilizer is at anangle to the edge of the elevator, hence the appearance of a droop. Hereare a few pictures from my files of Pietenpols in cruise flight:This shows the difference in angles I was talking about. See the angle ofthe edge of the horizontal stabilizer, compared to the edge of the elevator,which is straight? This is what creates the illusion of tail droop. Youreye tries to make the two edges line up.This one is a picture of Gene Rambo flying his son, Will, in my airplane.In this picture the horizontal tail is just about edge on, so the side ofthe stabilizer doesn't give the impression that the elevator is drooping.Looks pretty straight to meHere's another picture of my plane in flight:Here the angle is different and the side of the stabilizer does make it looklike the elevator is slightly down, but I assure you it's not.Here's Mike Cuy's airplane, photo taken from mine. Note his tail - nodroop.Here's Randy Bush's airplane, photo taken from Ryan Mueller's (now JohnHofmann's) N502R. Notice the tail. Where's the supposed droop?Lastly, this picture shows Kevin Purtee on the left, Shad Bell in thecenter, and me on the right (photo taken by Bill Church during Brodhead2011). You will note that my tail is slightly drooped with respect to theother two. The reason for this is that I was having to push my littleContinental A65 for all it was worth to keep up with those two Corvairpowered Pietenpols, and I had to hold the nose down to maintain my positionin the formation and keep it from climbing at that speed.There may be a slight droop due to downwash from the wing, but other thanthat, I don't think the dreaded tail droop exists at all. Build it to theplans, and build it straight and it should fly just fine.Jack PhillipsNX899JPSmith Mountain Lake, Virginia-----Original Message-----
RE: Pietenpol-List: Re: Speaking of outdated stuff? Center section fuel
Original Posted By: owner-pietenpol-list-server(at)matronics.com
In this picture, Lee Graybill, a retired AA pilot and longtime PT-22 flyer,pulled up alongside. He later told me, without being asked, that he hadeyeballed my rigging and noted no elevator deflection, nor any ailerondeflection (and was impressed with the 'look' of the plane!). Admittedly, Iwas pushing the airspeed a bit to the high 70's, as his Baby Ace is muchfaster. I believe it is Dick Navratil who gives a lecture at Brodhead abouttweaking the horizontal stab to correct tail-low conditions. I believe thatmay be useful on some airplanes depending on weight and preferred flyingspeed.Gary BootheNX308MB
In this picture, Lee Graybill, a retired AA pilot and longtime PT-22 flyer,pulled up alongside. He later told me, without being asked, that he hadeyeballed my rigging and noted no elevator deflection, nor any ailerondeflection (and was impressed with the 'look' of the plane!). Admittedly, Iwas pushing the airspeed a bit to the high 70's, as his Baby Ace is muchfaster. I believe it is Dick Navratil who gives a lecture at Brodhead abouttweaking the horizontal stab to correct tail-low conditions. I believe thatmay be useful on some airplanes depending on weight and preferred flyingspeed.Gary BootheNX308MB
RE: Pietenpol-List: Re: Speaking of outdated stuff? Center section fuel
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Maybe he needs the money. Those forums pay incredibly well.Jack PhillipsNX899JPSmith Mountain Lake, Virginia-----Original Message-----
Maybe he needs the money. Those forums pay incredibly well.Jack PhillipsNX899JPSmith Mountain Lake, Virginia-----Original Message-----