Date: Sat, 20 Jan 96 09:25:24 From: jvasher@ic.net Subject: using plans as a template isn't that a no no? I was always told to use paper (which shrinks and expands as tempature changes) is a no no but yet I read in chapter 4 mailing list this occurs all the time. Can't you lay out on the foam using dimensions or is this not all that critical. Also, the impression I have gotten from what I'm reading that the bulk heads are flat serfaces layed glass on foam. if this is the case why not rough cut the foam to the size and then make up a plywood template to the actual size then use a router and a straight bit with a roller bearing to trim back to the proper size of the template. this would give some very clean edges.. (Or am I just making this tougher then it needs to be) Love to hear more oppinions on this... jvasher@ic.net Cozy Builder wanna b' Date: Sat, 20 Jan 1996 15:41:53 -0500 (EST) From: Bill Walsh Subject: Re: using plans as a template isn't that a no no? On Sat, 20 Jan 1996 jvasher@ic.net wrote: > Date: Sat, 20 Jan 96 09:25:24 > From: jvasher@ic.net > To: cozy_builders@hpwarhw.an.hp.com > Subject: using plans as a template isn't that a no no? > > > I was always told to use paper (which shrinks and expands as tempature changes) is a no > no but yet I read in chapter 4 mailing list this occurs all the time. Can't you lay out > on the foam using dimensions or is this not all that critical. Also, the impression I > have gotten from what I'm reading that the bulk heads are flat serfaces layed glass on > foam. if this is the case why not rough cut the foam to the size and then make up a > plywood template to the actual size then use a router and a straight bit with a roller > bearing to trim back to the proper size of the template. this would give some very clean > edges.. (Or am I just making this tougher then it needs to be) Love to hear more > oppinions on this... > > jvasher@ic.net Cozy Builder wanna b' > > > Though somethings are made easier by innovative thinking....I get the impression that you are trying to make things to the point you may not finish your project in this century. Your bulkhead observation is amiable but the truth is that if you rough cut and use a sabre saw to get the correct outside dimensions of the bulkhaed you'll do fine...When you fit to the sides you will have to do some dremmel work to get them aboslutely correct, even then you will have flox at the joints and tape to correct any flaws. The other thing about the patterns .....I went to a blueprint place and had them do dupe's of the drawings and then cut the copies and pasted on the patern material....It's the way Nat says to do it......Advice, keep it simple and basic. You'll learn this as you progress...Any other input out there???? Date: Sat, 20 Jan 1996 20:57:25 -0500 From: RonKidd@aol.com Subject: Re: using plans as a template isn't that a no no? You are worrying yourself to death! There is nothing in a Cozy airframe that requires the kind of tolerances you are concerned with. I was building with a guy like fhis for a while. He would call me at 3:00 AM worrying about something insignifigant. My advice to him was don't worry about it. If you don't understand it, follow plans and it will work out. He started building in '86 and is still not on the gear! Mine flew in '90. Build it as per plans and don't sweat the small stuff, you will end up with an incredible airplane. Ron Kidd Cozy N417CZ Date: Sun, 21 Jan 1996 13:53:20 -0500 From: JHocut@aol.com Subject: Re: using plans as a template isn't that a no no? >I went to a blueprint place >and had them do dupe's of the drawings and then cut the copies and pasted >on the patern material Just be careful with this, I had the same idea but when I got my copies back decided to check them against the originals. Guess what, they didn't match. The copies were off by about 4% in the X axis and maybe 7% in the Y axis. I talked to the guys at the blueprint place about this, they said that it was not possible to get EXACT reproductions with photographic type equipment, and that bluelines were even worse. They told me the only way to get exact copies is with offset printing, and that's terribly expensive (it suddenly became clear why the plans cost what they do). Just in case anyone isn't aware of it, Cad files are available in the archives of the bulkheads so if you have access to a good plotter you can get very accurate drawings of these. Jim Hocut Cozy MK IV #448 From: Epplin_John_A@hpmail1.90.deere.com Date: Thu, 14 Nov 96 08:24:06 -0600 Subject: RE: COZY: Winglet Alignment, Voritilons & Airfoil Shape > > > ---------- > > Providing the templates on paper (as is the case with the Cozy) is not ideal, > the paper changes shape significantly due to humidity etc. The templates > should really be provided on mylar film or other "stable" material f > reasonable accuracy is to be obtained. > I have the same feelings about this. I found the Eppler 1230 (?) airfoil on some web site in coordinate pairs. Plotting this after sizing it to the largest template provided with the cozy plans shows the upper surface to be within paper tolerance, however the lower surface is far from the same airfoil. Somewhere I read that the Cozy Mk4 airfoil was a modified eppler 1230. I asked Nat what the modification might be, he did not know. He got the airfoil from Rutan. I have asked several people if there was a set of coordinates available for the Cozy airfoil. I can generate these from the templates I have but would like to go back to the original if I could. I can then use these to cut templates with a CNC machine in order to produce the best possible job. Any body out there know where I can find these or have another idea? John Epplin Mk 4 #467 From: Nick Parkyn Subject: RE: COZY: Winglet Alignment, Voritilons & Airfoil Shape Date: Thu, 14 Nov 1996 14:24:15 +-1100 ---------- From: INFINITY Aerospace[SMTP:72124.347@compuserve.com] Sent: Thursday, November 07, 1996 4:25 PM To: Cozy/Canard Builders Subject: COZY: Winglet Alignment, Voritilons & Airfoil Shape On another note, have you all ever wondered why there seems to be such = a wide variation in scratch built canard aircraft performance reports? I = think a big factor is that the builders do try to keep the shape of their canard = airfoil using a template per plans (which is critical), but many take whatever = the wing and winglet foam core gives them for airfoil shape after hotwire. Providing the templates on paper (as is the case with the Cozy) is not = ideal, the paper changes shape significantly due to humidity etc. The = templates should really be provided on mylar film or other "stable" = material f reasonable accuracy is to be obtained.