Original Posted By: Martin Vandenbroek [mailto:mav(at)ece.ucsb.edu]
Martin,I contend that as the water seeps through the floors and walls, itevaporates. Evaporation consumes heat and therefore the body of air withthe vapor in it is colder than the air that does not have the vapor in it.So you different temperatures.All I know is that two friends of mine have identical reasonably sealed uphangars here in Mn. One has his dehumidifier on the wall about six feet upand the other has it on the floor. The one on the floor gets emptied twotimes a day. the one on wall gets emptied maybe once day.I also read somewhere that the dehumidifiers should go in the lowest spot.chris-----Original Message-----
Pietenpol-List: RE: water vapor
Re: Pietenpol-List: wing rib drawings
Original Posted By:
This is the same issue I have been dealing with. Here is what I have foundso far.First, paper is not dimensionally stable. The aircraft companies that Ihave worked for use vellum or mylar for prints instead. Paper does have theadvantage that it is cheap. Also, photo copy machines and especially faxmachines are not to be trusted. One trick that I have learned is to put abox or circle of a known size on the the print (in an otherwise emptycorner) before copying. Later, when you want to use the print you can checkthe dimensions of your box and thus have confidence in it.As for the airfoil. The first thing I noticed is that it is dimensioned ina rather unconventional manner, so be very careful when plotting it out.Beyond that, I have noted differences between the Pietenpol airfoil printedwith the Air Camper plans in the 32 manual and the airfoil printed with thesky scout plans in the 33 manual. This is interesting because according tothe 33 manual the Sky Scout airfoil is the same as the Air Camper airfoil.There are two differences: 1. The 6.0 width dimension which the text in the32 manual says should be 6.125 is back to 6.0 in the 33 manual (the 6.0appears to give a better curve), 2. the dimensions at the trailing edge areslightly different in the 33 manual (in this case the 32 manual appears togive a better curve.) Like everything else in homebuilding there are somedecisions that you will to make for yourself.Out of curiosity I have been playing with the airfoil in XFOIL (a greatpiece of 2d CFD software) in the hopes of figuring out how good the airfoilis/was. There are still a few more things I want to try in hopes of gettinga more accurate solution, but so far it looks like the airfoil is an ok slowspeed airfoil. Not suprising it has good lift, but not so good dragnumbers. It also seems to have a very low pitching moment when comparedwith other airfoils. When I get numbers in which I have confidence I willprobably post them on my web page.Best of luck with your project,Kevin Holcombhttp://www.angelfire.com/va2/aerodrome/----- Original Message -----
This is the same issue I have been dealing with. Here is what I have foundso far.First, paper is not dimensionally stable. The aircraft companies that Ihave worked for use vellum or mylar for prints instead. Paper does have theadvantage that it is cheap. Also, photo copy machines and especially faxmachines are not to be trusted. One trick that I have learned is to put abox or circle of a known size on the the print (in an otherwise emptycorner) before copying. Later, when you want to use the print you can checkthe dimensions of your box and thus have confidence in it.As for the airfoil. The first thing I noticed is that it is dimensioned ina rather unconventional manner, so be very careful when plotting it out.Beyond that, I have noted differences between the Pietenpol airfoil printedwith the Air Camper plans in the 32 manual and the airfoil printed with thesky scout plans in the 33 manual. This is interesting because according tothe 33 manual the Sky Scout airfoil is the same as the Air Camper airfoil.There are two differences: 1. The 6.0 width dimension which the text in the32 manual says should be 6.125 is back to 6.0 in the 33 manual (the 6.0appears to give a better curve), 2. the dimensions at the trailing edge areslightly different in the 33 manual (in this case the 32 manual appears togive a better curve.) Like everything else in homebuilding there are somedecisions that you will to make for yourself.Out of curiosity I have been playing with the airfoil in XFOIL (a greatpiece of 2d CFD software) in the hopes of figuring out how good the airfoilis/was. There are still a few more things I want to try in hopes of gettinga more accurate solution, but so far it looks like the airfoil is an ok slowspeed airfoil. Not suprising it has good lift, but not so good dragnumbers. It also seems to have a very low pitching moment when comparedwith other airfoils. When I get numbers in which I have confidence I willprobably post them on my web page.Best of luck with your project,Kevin Holcombhttp://www.angelfire.com/va2/aerodrome/----- Original Message -----
Re: Pietenpol-List: wing rib drawings
Original Posted By: Larry Neal
RE: Pietenpol-List: wing rib drawings
Original Posted By: owner-pietenpol-list-server(at)matronics.com
when I make wing ribs, I redraw the rib, using the dimensions given, rightonto the wood that I use for the base of the jig. You can use two 2 footstraight edges for the chordline, sliding them against one another to keepthe line straight. that is important. I convert all the dimensions fromfractional to decimal and then use a short six inch rule that is calibratedin hundredths of an inch, and a drafting square to keep the plotting pointproper in relation to the chordline and accurate in dimension.Make sure you use some wood that has been around a while so it isdimensionally stable.Just put the blocks to hold the capstrips and such at the plotting pointsalong the top and bottom. Make these blocks 1/16 inch less in hieght thanthe capstrip is wide so you tend not to glue to them. Use a piece of woodthat will be the same dimensions as your spars for where the spars are togo.I often wonder why anyone would go through the trouble and worry about usinga paper pattern glued to the wood base? Transferring the dta from drawingto the wood allows you to become one with the airfoil and measuringdiscrepencies as we know exist, will jump right out at you.chris Bobka-----Original Message-----
when I make wing ribs, I redraw the rib, using the dimensions given, rightonto the wood that I use for the base of the jig. You can use two 2 footstraight edges for the chordline, sliding them against one another to keepthe line straight. that is important. I convert all the dimensions fromfractional to decimal and then use a short six inch rule that is calibratedin hundredths of an inch, and a drafting square to keep the plotting pointproper in relation to the chordline and accurate in dimension.Make sure you use some wood that has been around a while so it isdimensionally stable.Just put the blocks to hold the capstrips and such at the plotting pointsalong the top and bottom. Make these blocks 1/16 inch less in hieght thanthe capstrip is wide so you tend not to glue to them. Use a piece of woodthat will be the same dimensions as your spars for where the spars are togo.I often wonder why anyone would go through the trouble and worry about usinga paper pattern glued to the wood base? Transferring the dta from drawingto the wood allows you to become one with the airfoil and measuringdiscrepencies as we know exist, will jump right out at you.chris Bobka-----Original Message-----
RE: Pietenpol-List: wing rib drawings
Original Posted By: owner-pietenpol-list-server(at)matronics.com
Kevin,Send us the data you discover.Chris-----Original Message-----
Kevin,Send us the data you discover.Chris-----Original Message-----
Re: Pietenpol-List: wing rib drawings
Original Posted By: "Christian Bobka"
Air foils are fairly forgiving for small errors. The important thing is thefastening to the spar is good and every rib have the same smooth profile.The you get a good structure and a smooth consistent airfoil. Some go sofar as to make a router jig so that every rib is machined to be identical.Cy Galley, TC - Chair, Emergency Aircraft Repair, Oshkosh----- Original Message -----
Air foils are fairly forgiving for small errors. The important thing is thefastening to the spar is good and every rib have the same smooth profile.The you get a good structure and a smooth consistent airfoil. Some go sofar as to make a router jig so that every rib is machined to be identical.Cy Galley, TC - Chair, Emergency Aircraft Repair, Oshkosh----- Original Message -----
RE: Pietenpol-List: wing rib drawings
Original Posted By: "Christian Bobka"
I built a router jig for my ribs. To keep the ribs the same airfoil was onereason, but the primary reason was to keep the leading edge stick straightbetween ribs.I was finding that it was very difficult to keep the leading edge notch inthe same location on each rib (remember, mine is a GN-1 rib which is a pietairfoil with different spar locations)I have seen framed up wings where the leading edge stick is pretty wavy whenyou look down from one end. While it doesn't end up mattering when coveredwith aluminum or wood leading edge, it's something that would have botheredme so I made the jig. Every wib is now within 1/64" of each other and ittakes virtually no more time to do them that way.pics of my jig are herehttp://www.imagedv.com/aircamper/log/image-pag ... 4-02.htmDJ VeghMesa, AZGN-1/Piet hybridwww.raptoronline.com N74DV________________________________________________________________________________
I built a router jig for my ribs. To keep the ribs the same airfoil was onereason, but the primary reason was to keep the leading edge stick straightbetween ribs.I was finding that it was very difficult to keep the leading edge notch inthe same location on each rib (remember, mine is a GN-1 rib which is a pietairfoil with different spar locations)I have seen framed up wings where the leading edge stick is pretty wavy whenyou look down from one end. While it doesn't end up mattering when coveredwith aluminum or wood leading edge, it's something that would have botheredme so I made the jig. Every wib is now within 1/64" of each other and ittakes virtually no more time to do them that way.pics of my jig are herehttp://www.imagedv.com/aircamper/log/image-pag ... 4-02.htmDJ VeghMesa, AZGN-1/Piet hybridwww.raptoronline.com N74DV________________________________________________________________________________