Brodhead Pietenpol Association

Original Posted By: Michael D Cuy
Subject: Pietenpol-List: Piet information listI think the questionaire on Piets is an excellent way of cataloging the variations in the airplanes. Unless I missed it, there's one addition I would liketo see. When brakes are added to a Piet, some folks move the mains axis forward to reduce the tendency to nose over on heavy braking (mine have been movedforward 2.5" from the plans). We could include the dimension from prop hub to the axle....Whatta ya think?....Carl Vought________________________________________________________________________________Date: Tue, 13 Jan 2004 10:10:12 -0500

Original Posted By: "DJ Vegh"
Subject: Re: Pietenpol-List: Piet information listGood idea Carl, one question though is what to use for a datum to measure from. Since people move their engine forward sometimes 6 -8 inches for CG I don'tthink that will work. Same thing with the wing leading edge, people move the wing forward and backward too. How about the front Ash floor cross strut?Rick HollandI think the questionaire on Piets is an excellent way of cataloging the variations in the airplanes. Unless I missed it, there's one addition I would liketo see. When brakes are added to a Piet, some folks move the mains axis forward to reduce the tendency to nose over on heavy braking (mine have been movedforward 2.5" from the plans). We could include the dimension from prop hub to the axle....Whatta ya think?....Carl Vought ________________________________________________________________________________

Original Posted By: At7000ft(at)aol.com
OK, I'm going to stick my nose in once more. To be useful you need to know wherethe contact point of the tire is in relation to the CG in a level attitude.Sorry guys but all the other measurements don't help much from a nose over pointof view. The other thing that is needed is the height from the ground tothe CG. With those measurements you can calculate the nose over moment and withthe tail force and arm you can calculate exactly how much brake you can useverses the airspeed. That is what tells you if you are going to have a "grazer"or a tail dragger.Hank J ----- Original Message -----

Original Posted By: dave rowe

Original Posted By: dave rowe

Original Posted By: hjarrett
Hank J.Good information. Can you give the math to go with the measurments? Alex S. ----- Original Message -----

Original Posted By: "Hodgson, Mark O"
Wicks will be comparable in price to AS&S and if you send a photocopy of theshapes for the tail they will mill them for you for about $ 1.65 per foot.You don't need much made so it is cheaper to pay them than to buy the routerbits to do it yourself.Dennis E.----- Original Message -----

Original Posted By: Alex Sloan
I have a formula that I got from Greg Cardinal somewhere around here that usesthe weight of the ship level and then the weight of the ship in three point attitude,loaded, of course. It will determine the vertical CG of the ship whenloaded. Maybe the math guys can come up with it faster than I can.Chris Bobka ----- Original Message -----

Original Posted By: Michael D Cuy
Subject: Re: Pietenpol-List: Piet information listIn a message dated 1/13/04 7:11:56 AM Central Standard Time, Carbarvo(at)aol.com writes:>Carl, The datam on the Pietenpol is the firewall. I'll include you're suggestion in the 'Alterations' section of the Infomation Sheet. My split axle is in the plans location of 17" behind the firewall. I have brakes, for run up, and taxiing in tight areas - not to stop the landing roll out. If you move the axle forward, you place more weight on the tailskid/ wheel, and it will not come up as quick on the take off run.Chuck Gantzer.3 days in a row, of Piet wether !!________________________________________________________________________________Date: Wed, 14 Jan 2004 07:37:08 -0500

Original Posted By: "John Dilatush"
Subject: Re: Pietenpol-List: Piet information listHank - given this data how do you calibrate how hard you can press on the brakes at a given speed to avoid grazing? Rick H.OK, I'm going to stick my nose in once more. To be useful you need to know where the contact point of the tire is in relation to the CG in a level attitude. Sorry guys but all the other measurements don't help much from a noseover point of view. The other thing that is needed is the height from the ground to the CG. With those measurements you can calculate the nose over moment andwith the tail force and arm you can calculate exactly how much brake you can use verses the airspeed. That is what tells you if you are going to have a "grazer" or a tail dragger.Hank J ________________________________________________________________________________

Original Posted By: "Dave and Connie"
awwww come on! you used headsets in a Tcraft?!!!:-)DJ VeghN74DVMesa, AZwww.imagedv.com/aircamper----- Original Message -----

Original Posted By: At7000ft(at)aol.com
You need to calculate the thrust and know the moment arm of the prop which givesyou the thrust component of the nose over moment, the brake force (based onspeed of the aircraft to calculate the weight on the wheels and the local frictioncoefficient) and the vertical CG location, which gives you the nose overmoment from the wheel brakes, the deceleration of the aircraft times the heightof the CG for the inertia contribution to the nose over moment, and the distancebehind the tire contact point of the CG (which changes as the attitude ofthe plane changes, that also changes the lift, changing the weight on the wheelsthat changes everything else). Then you do the calculation solving for allthe moments at say every 2 MPH increment to determine the critical speed, anglesand brake force. You also have to factor in the down load available fromthe tail and its arm solving for the point where the elevator looses effectiveness.The one factor that is hard to calculate is how hard your "pucker" istrying to suck your rear to the pavement and the moment arm from the wheel contactpoint to the seat as the nose starts to go over.Three things are derived from the whole mess.1) That's why the engineer gets paid as much as he does2) Now you know why the tricycle gear is so popular with manufacturers3) That's why we use a "Rule of Thumb" for the angleIf you REALLY want to know the answer to the above I have done it before but ittakes some time and can get expensive. It IS very informative and, by the way,I wrote the above as I sat in front of the computer so some factors are probablymissing. I would normally do it on paper to make sure I didn't miss anythingand them spread sheet it for each condition.Anybody want to help finance the paint job on my Taylorcraft? ;-)Hank J ----- Original Message -----