Date: Sat, 30 Dec 1995 21:51:40 -0500 From: Chris341CC@aol.com Subject: Fusalage weight Greetings everyone, I would appreciate input from anyone who kept record of their fusalage weight at the end of Ch. 7 (or those of you that may be at that point now). I have just completed Ch. 7 and my fusalage weighs approx. 86 lbs.. Nat *estimated* that the fusalage should weigh approx. 80 lbs at the end of Ch 8. If this estimate is accurate that puts me twelve or thirteen lbs. over the target(assuming that Ch. 8 will add six or seven lbs.). I'm sure most builders would consider my lay-ups to have the proper epoxy/glass ratio and I try hard to build as light as possible, so I'm not sure if I could have weighed in any lighter. Oh well, I'm not one to nit-pick things, but I would like to know if I'm within range. Thanks, Chris A. Mitchell N341CC Thanks, Chris A. Mitchell N341CC Date: Wed, 10 Jan 1996 15:40:49 -0600 From: tims@enet.net (Tim Sullivan) Subject: Ch 7-Bottom Taper Question I'm having a problem with how the taper should look starting from the firewall to a pont 25" forward on the fuselage sides. DwG M-8 shows how it should look at the firewall but as the taper thins out toward the front does the taper come to a single point at the lower longeron or a perpendicular line? Tim Sullivan (tims@enet.net) Phoenix, AZ | * | Cozy MK IV Builder #470 |-----(/)-----| The journey begins 8/10/95 / \ Current Status: Ch 7 o o Date: Mon, 05 Feb 1996 07:47:57 -0600 From: tims@enet.net (Tim Sullivan) Subject: Ch 7-Correction...maybe Called Nat last night in a bit of a panic. I'm finishing up Ch7 and was measuring the side for the 3 uni layup 4" wide strips that are called for from the engine mount to a point past the landing gear bulkheads. The panic. After checking with the tape measure and revisting my first grade math (over and over) I couldn't for the life of me see how 8,10 and 12 inches forward of the fire wall would work. Those length come out in the middle of the landing gear bay. Did I miss a post from someone else with this problem? Anyway, after talking to Nat he said "Whatever works is fine." Suprisingly not the type of answer what I would have expected from the designer. He did explain, which was obvious, the reasoning of why the UNI was there which is to distribute the load from the fire wall. I was just calling to comfirm that I didn't have any major boo boos on bulk head placement that have finally came back to get me. Anyway just for your info, those who are on Ch7, I used 20, 22 and 24 inch lengths and according to Nat the figure (24?) lengths are not correct. Your milage may vary. This does mean that now I get to sit in the fuselage and make airplane sounds. :) Tim Sullivan (tims@enet.net) Phoenix, AZ | * | Cozy MK IV Builder #470 |-----(/)-----| The journey begins 8/10/95 / \ Current Status: Ch 7 o o From: Michael Antares Subject: RE: Ch 7-Correction...maybe Date: Mon, 5 Feb 1996 19:21:11 -0800 Called Nat last night in a bit of a panic. I'm finishing up Ch7 and was measuring the side for the 3 uni layup 4" wide strips that are called = for from the engine mount to a point past the landing gear bulkheads. The panic. After checking with the tape measure and revisting my first = grade math (over and over) I couldn't for the life of me see how 8,10 and 12 inches forward of the fire wall would work. Those length come out in = the middle of the landing gear bay. Did I miss a post from someone else = with this problem? Anyway, after talking to Nat he said "Whatever works is fine." Suprisingly not the type of answer what I would have expected = from the designer. He did explain, which was obvious, the reasoning of why = the UNI was there which is to distribute the load from the fire wall. I was just calling to comfirm that I didn't have any major boo boos on bulk = head placement that have finally came back to get me. Anyway just for your = info, those who are on Ch7, I used 20, 22 and 24 inch lengths and according to = Nat the figure (24?) lengths are not correct. Your milage may vary. I think the answer is that although the picture seems to show the = strips extending past the landing gear bulkhead, most of us = (certainly me) laid the strips in per the instructions and not as = sort of shown in the drawing--frankly I didn't even notice the = discrepancy until pointed out by you! That is to say = I laid the strips from 2" past the engine mount hardpoint and = extending 8, 10 and 12 inches from the edge. Michael Date: Tue, 13 Feb 1996 23:35:08 -0500 From: Fritzx2@aol.com Subject: Fuse Bottom VOR Antenna Location I would appriciate anyone who has finished installing the front wheel taking four measurements and passing them on to me. Specifically, I would like to know the included angle of the VOR antenna for your installation, the length of each of the poles, the distance back from the front face of F22 to the tip of the antenna assuming you have installed the antenna as shown in the plans with the tip facing aft and the poles facing forward, and your clearance from the inside of the antenna perpendicular to where it passes closest to the wheel cutout. _________________________ | | \ | \ | \ F22 | \ | / <--------VOR | / | / |_________________________ Bottom View of the Fuselage I have ordered the materials from RST along with the articles on antenna construction. Even if you didn't install the antenna because you were going to place it somewhere else or plan to use GPS (which I will most likely use but since the materials were so cheap and installation so quick I decided to put one in), I would appreciate if you could characterize the wheel profile cutout and location. Thanks, John Fritz fritzx2@aol.com From: Marc J. Zeitlin Subject: Fuse Bottom VOR Antenna Location (fwd) Date: Wed, 14 Feb 96 22:44:32 EST John Fritz asks: >...... Specifically, I would like to >know the included angle of the VOR antenna for your installation, the length >of each of the poles, the distance back from the front face of F22 to the tip >of the antenna assuming you have installed the antenna as shown in the plans >with the tip facing aft and the poles facing forward, and your clearance from >the inside of the antenna perpendicular to where it passes closest to the >wheel cutout. 1) Included Angle: ~85 degrees (I might have been able to go to 90 or a bit more, but I didn't want the copper foil tape to go around the bottom corner of the fuselage). 2) Length of poles: 22.8" (as defined by Jim Weir for NAV antennae) 3) F22 to apex of antenna: ~37.5" (~5" in front of Landing Brake hinge) 4) Clearance: I haven't cut out the wheel opening yet, but it looks as though the clearance will be about 11" on either side. I ran my coax (the teflon plenum type, if you can get it) straight forward to the forward face of the Instrument panel, and then straight up just to the side of where the wheel opening will be (I hope! :-) ). >...I would appreciate if you could characterize the wheel profile >cutout and location. As shown in the plans and judging by the wheel cover that I got from Featherlite, it's about 6" - 7" wide and 12" long starting just in front of the instrument panel (with a rounded back end right next to the I.P. and then tapers narrower to just over the width of the strut (~1.5" - 2") by the time it reaches F22. Hope this helps. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Sun, 3 Mar 1996 16:48:00 -0500 From: JHocut@aol.com Subject: Ch 7 - Vac Bag? Anyone figured out how to vac. bag any or all of the fuselage exterior? Looks like it's going to ba a challenge. Jim Hocut Cozy IV # 448 Date: Tue, 2 Apr 1996 21:15:20 -0600 From: campbell@ee.umn.edu (prof S. A. Campbell) Subject: Chapter 7 Help please. I'm working on Chapter 7 and starting to shape the fuselage. The shaping begins by cutting the back end of the foam starting from a point 25" forward of the firewall back to the firewall. YThe plans explain the amount to be removed laterally, but I'm s not sure about the vertical dimension. The plans refer to figure 8 which shows a dotted region where the foam should be removed. This region does not extend all the way to the ends of the longerons. Looking over the rchives no one has asked this question before. Not great self confidence wise. Any one you experienced builders help me with this one? Thnaks in advance Steve Campbell PSbn Date: Tue, 02 Apr 1996 20:21:00 -0800 From: Michael Antares Subject: Re: Chapter 7 At 09:15 PM 4/2/96 -0600, you wrote: >Help please. I'm working on Chapter 7 and starting to shape the fuselage. >The shaping begins by cutting the back end of the foam starting from a >point 25" forward of the firewall back to the firewall. YThe plans >explain the amount to be removed laterally, but I'm s not sure about >the vertical dimension. The plans refer to figure 8 which shows a dotted >region where the foam should be removed. This region does not extend >all the way to the ends of the longerons. Looking over the rchives >no one has asked this question before. Not great self confidence wise. >Any one you experienced builders help me with this one? >Thnaks in advance >Steve Campbell >PSbn > This is the one place where I actually put in a call to Nat. As it turns out it is really not that critical since much of the area will be covered by the strake and strake fillet. However I found that by making a smooth transition from the firewall to the forward point you mentioned, you will end up with a good looking fuselage side. One way that I could tell how smooth the transition was, was by observing the curve of the blue top foam turning into the tan under foam. When the shaping was finished the curve was a nice smooth one angling from the bottom up towards the top. The dotted cutout is principally to expose the longeron to provide a later attachment to the main spar. After removing all of the foam down to the surface of the longeron, I angled downward from the bottom of the longeron at an approximately 45 degree angle. Others further along in construction can perhaps amplify on this cutout. Again I assume it is not very critical. Regards, 6077 Old Redwood Highway Penngrove, CA 94951 707.664.1171 Systems engineering hardware/software Date: Wed, 3 Apr 1996 10:34:22 -0500 From: JHocut@aol.com Subject: Re: Chapter 7 In a message dated 96-04-02 22:24:27 EST, campbell@ee.umn.edu wrote: >Help please. I'm working on Chapter 7 and starting to shape the fuselage... You're not alone, in fact I just finished screwing my fuse up due to this confusion also. Marc sent me a real good description of how it should be, but unfortunately I didn't save it. Maybe my interpretation will shed some light for you: Visualize a hot wire cutter, one side fastened on a pivot 25 inches forward of the firewall, right on the edge of the foam at the "top" corner (I say top because the fuse is upside down). Now visualize how the foam will be cut if you take your imaginary hot wire cutter and slide it along the firewall, with the other end staying put on the pivot. You will have cut out roughly a triangle of varying depth, deeper at the firewall, shallower toward the front. Anyway, as I understand it that's the approximate shape you're shooting for, before smoothing the edges etc. Hope my $.02 helped a little. Jim Hocut jhocut@aol.com Date: Wed, 03 Apr 1996 11:28:50 -0600 From: tims@enet.net (Tim Sullivan) Subject: Re: Chapter 7 >Help please. I'm working on Chapter 7 and starting to shape the fuselage. >The shaping begins by cutting the back end of the foam starting from a >point 25" forward of the firewall back to the firewall. YThe plans >explain the amount to be removed laterally, but I'm s not sure about >... May I add one more item to the replies re: this little "fun" part of the plans (I called Nat too, think he would get the message). You might, while sanding, start to cut into the electrical conduit. I did and three others I know have as well. Just stop at that point on the depth. Good luck Tim Sullivan (tims@enet.net) Phoenix, AZ | * | Cozy MK IV Builder #470 |-----(/)-----| The journey begins 8/10/95 / \ Current Status: Ch 9 o o Date: Wed, 3 Apr 1996 12:50:01 -0500 From: JHocut@aol.com Subject: Re: Chapter 7 In a message dated 96-04-03 11:34:19 EST, campbell@ee.umn.edu wrote: >Just to be sure that I understand, the front pivot point remains fixed? >That means that the point 25" from the firewall is >just that - a point with no vertical extent, and that the height of the cut >increases as one moves back toward the firewall. Is this right? EXACTLY. I went through this about a week ago, actually screwed up a little bit because I don't know when to leave well enough alone. Had I left it at the stage as described it would have been fine. But NO, I had to try and improve upon things, and did like you said and gave that "point" vertical dimensions. Well, I wound up cutting into my electrical ducts, so now have some fixing up to do. It's really not all that critical though, as someone else has said, most of this area isn't all that visible. Jim Hocut jhocut@aol.com From: Marc J. Zeitlin Subject: Re: Ch. 7 contouring Date: Wed, 3 Apr 96 13:12:34 EST Jim Hocut mentioned the message I sent to him in relation to this - here's the gist: >Basically, you leave the foam alone in front of the spar cutout - it >stays the whole thickness. On the fuselage bottom, and around the >corners (almost all the way up to the little triangle portion of the >firewall) the foam gets sanded or carved back so that it's flush with >the firewall edge (or whatever it says in the plans). You end up with a >transition region between these two area, and it runs diagonally from >that little triangle down at about a 30 degree angle to the lower >triangular longeron. In this transition region, you just sand or carve >the foam so that it blends together nicely. As long as you've got a >smooth transition, you'll be OK. The strake will cover the whole area >in front of the spar, and some foam blocks will create a "strake root >fairing" down onto the lower fuselage. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Thu, 4 Apr 1996 18:36:42 -0500 (EST) From: Randy Crutfield Subject: Another Chapter 7 question Hello, I'm new to this group, and have a question that has probably already been answered here, if so just RTFM me and I will extract the archives and research the answer. How far do the joggles extend down the sides for the landing gear cover? Does the cover extend beyond the last inserts on the bulkheads, in other words does it transition from the flat surface of the bottom onto the curve at the edges? If so, how far down the curved side does it extend? On a related note, does the foam that is inserted outside of the plywood corner braces(between the landing gear bulkheads) take on the contour of the sides up to the point where the foam insert is even with the top of the braces side view ___________ | | or does it take the contour of the sides and have cutouts that correspond to the plywood inserts, side view |\_________/|. Seems like it might be the later to accommodate the landing gear legs, but I'm not sure at this point. Hope that the simplified drawing makes sense and doesn't get screwed up by your browser or word processor and look totally insane. Thanks for the advice on advance, Randy From: Lee Devlin Subject: Re: Another Chapter 7 question Date: Thu, 4 Apr 96 16:59:13 MST > How far do the joggles extend down the sides for the landing gear > cover? Does the cover extend beyond the last inserts on the bulkheads, > in other words does it transition from the flat surface of the bottom > onto the curve at the edges? If so, how far down the curved side does it > extend? I had the exact same confusion when I was doing chapter 7. I elected to take the joggle down to the longeron, which also answers your next question. If the joggle is extended down to the longeron, then the foam installed outside the triangle pieces needs to be sanded down to the joggle level as well. However, after just completing the landing gear cover, it looks a little funny since the cover only extends to the (approximate) centerline of the gear. But you don't have the gear mounted until Ch 9. so there was no way to know where that is going to be! In the end, I will need to build up both the l.g. cover and the side of the fuselage with fairings to meet up with the landing gear. This should cover this 'mistake'. I don't know if there is a 'right' answer to this question. Lee Devlin From: Marc J. Zeitlin Subject: Re: Another Chapter 7 question Date: Fri, 5 Apr 96 8:29:57 EST Randy Crutfield asked: > How far do the joggles extend down the sides for the landing gear > cover? Does the cover extend beyond the last inserts on the bulkheads, > in other words does it transition from the flat surface of the bottom > onto the curve at the edges? If so, how far down the curved side does it > extend? Well, my logic was that the L.G. cover wasn't going to go any further than the middle of the gear strut, and the gear strut couldn't be any further than the plywood gussets, so when I sanded the joggle into the foam, I stopped just past the top of the triangular gussets. As Lee Devlin said, there may be no "right" answer here - it probably doesn't make a lot of difference. Eventually you make a fairing that covers the strut-fuselage interface anyway, so unless you're way off, it gets covered up. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Fri, 05 Apr 1996 09:05:54 -0800 From: Michael Antares Subject: Another chap 7 question I'm pretty much agreeing with Marc's suggestion. The center line of the landing gear strut cross section is fairly in line with the top of the triangular pieces so that if you want the cover to expose everything up to the strut then that is how far the joggle should go. It seems from some photoes I have seen that some builders elect not to have the cover go that far but for me it was important to be able to easily remove the landing gear strut later--I have no good reason why I might want to remove it easily but in my obstinancy I felt that if the landing gear is held on with only two bolts, one should be able to remove it in a couple of minutes(!). That meant the cover would have to go all of the way to the strut. I'm sure that Marc will agree that making the cover is a project in itself. My 2 centavoes... Michael 6077 Old Redwood Highway Penngrove, CA 94951 707.664.1171 Systems engineering hardware/software Date: Sun, 14 Apr 1996 22:16:40 -0400 From: Jim Hocut Subject: Ch 7 - Joggles I just finished the last of the dreaded joggles, and as I feared I'll be doing some rework. Nothing terrible, just a pain in the neck. After seeing Marc's hassles with this I went to extra trouble to try and prevent problems, came up with my own Rube Goldberg method of holding all the glass down etc., and it still didn't come out real well. I wonder if anyone at all has had a relatively hassle free time with this part of the plans. If so maybe someone could share their secrets so everyone who's not to that point yet can have an easier time of it. I sure could have used an alternative way to do this, even though I pretty much knew what I was in for the results still left a lot to be desired. (I hope this is the last headache for a while, I'm a little bummed at the moment and am actually feeling the need to take a break from my project). Jim Hocut jhocut@mindspring.com Date: Mon, 15 Apr 1996 20:58:17 -0400 From: JQUESTCOZY@aol.com Subject: Re: Ch 7 - Joggles Jim, I also have troubles with joggles and trailing edges ect.. Some info on joggles that seemed to help me a little bit: First I tend to make any joggles or layup overlap areas a little deeper than called out to avoid a future bump and just fill joggles with a little more micro than the average guy. I bought some strips of mild steel 1/8 inch thick from the local hardware store, it came about 1.25 inches wide and about 36 inches long (cheap stuff ).After glassing I cut some pieces and lay/weigh in the joggles. It worked well on the landing gear cover for me and the F22 joggle. I actually use this 1/8 inch steel quite a bit for shimming, transferring holes and what not. I used it transfer the landing gear bulkhead holes to my gear tabs for a perfect fit prior to drilling. Wavy trailing edges: For curves like on the trailing edge of the gear strut. I cut some veneer or counter top material that I had about 1 inch wide and used it on each side of the trailing edge with some small clamps and it gave a smooth curve on the trailing edge. (use some wax paper or peel ply for release). It's flexable enough to bend yet stiff enough to hold a good edge. Much better than alum foil tape. I hope this helps someone.:-) John Wilemski Cozy #227 Date: Fri, 19 Apr 1996 09:28:52 -0400 (EDT) From: Randy Crutfield Subject: Chapter 7 question Where my fuselage sides meet F22, I have them even with the Aft of the bulkhead. This results in the sides curving up to the bulkhead and then the bulkhead interrupting this curve with it's flat width (1/4" +). Reading over the plans, it specifies that the area aft of F-22 for 1" should have a 1/16" depression sanded into it for later nose layups. Is the foam for the sides supposed to be even with the aft of the bulkhead, front of the bulkhead, (would leave the foam higher than the aft of the bulkhead and a void the width of the bulkhead) or should I sand the front edge of F22 down to match the contour of the sides. Possibly, just leave it as is and let the nose layups fill it and contour later to match the nose section ? Randy Date: Fri, 19 Apr 1996 10:22:38 -0400 From: Jim Hocut Subject: Re: Chapter 7 question - side contour @ F22 >Possibly, just leave it as is and let the nose layups fill it and contour >later to match the nose section ? My take on it is that this is the way to go. I'll be glassing the fuse bottom and sides this weekend, and had expended a great deal of mental energy wondering about this very question. The conclusioin I came to is that my Cozy isn't going to be shaped EXACTLY like Nat's, Marc's, yours, or anyone elses. As long as I do a reasonable job of contouring when I mate up the nose everything will work out fine. (BTW, my fuse sides wound up extending a little bit beyond F-22) Jim Hocut jhocut@mindspring.com Cozy IV # 448 From: Marc J. Zeitlin Subject: Chapter 7 question (fwd) Date: Fri, 19 Apr 96 10:33:12 EDT Randy Crutfield writes: >Where my fuselage sides meet F22, I have them even with the Aft of the >bulkhead............... >Is the foam for the sides supposed to be even with the aft of the >bulkhead, front of the bulkhead ............ I don't have the plans here at work, but the important thing is to have the fuselage the right LENGTH. The stations for each bulkhead must be correct. F22 must be at 22, while the firewall is at (whatever it's supposed to be). >............................... (would leave the foam higher than the >aft of the bulkhead and a void the width of the bulkhead) or should I >sand the front edge of F22 down to match the contour of the sides. If F22 sticks out further than the fuselage sides, you should sand it down. The sides should wrap smoothly around F22 with the 1/16" depression. You will need a slight radius (1/8" at least) on the corner as well, so that the UNI will wrap well. >Possibly, just leave it as is and let the nose layups fill it and contour >later to match the nose section ? Having just done this, I can tell you that you want the 1/16" depression to follow the expected contour of the fuselage sides, and NOT be parallel to the longitudinal axis (straight forward and back). You may even want to sand the foam down about 1/16" toward the rear of the depression, and 1/8" toward the front of the depression, as when you wrap the glass around the corner, it tends to be a little thicker there. I JUST BARELY squeaked by without having to build up a lot of micro to fair the nose into the fuselage. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: 19 Apr 96 15:31:57 EDT From: "William E. Buckley" <74744.2301@compuserve.com> Subject: NACA Scoop I just finished tracing the NACA scoop template onto the bottom of the fuselage and had the following problem. The template for the scoop is about .2 inches wider than the cutout in the rear landing gear bulkhead and about .2 inches more narrow than the cutout in the firewall. I then varified that both bulkheads were in compliance with their respective templates. Knowing that the dynamics of the NACA scoop are rather particular, I was wondering if I should make the bulkheads conform to the NACA template or build the NACA scoop within the shape already provided for by the bulkheads. Anyone else have this problem and if so which is the correct shape? Does it really matter? William E. Buckley (Cozy IV, #437, Chap 7) 74744.2301@compuserve.com From: Marc J. Zeitlin Subject: NACA Scoop (fwd) Date: Fri, 19 Apr 96 17:26:09 EDT William E. Buckley writes: >............. Knowing that the dynamics of the >NACA scoop are rather particular, I was wondering if I should make the >bulkheads conform to the NACA template or build the NACA scoop within the >shape already provided for by the bulkheads. Anyone else have this >problem and if so which is the correct shape? I had a similar, if not quite so disparate, experience. I figured that it was more likely for the scoop template to be correct than for the combination of bulkhead templates (not done on a CAD system) and idiosyncratic positioning (by me) to be correct. I widened or narrowed where necessary to match the scoop template. >.......... Does it really matter? I tried to search for NACA inlet scoop info on the WEB - found about a billion matches on ALTA VISTA and LYCOS, but no design detail :-). Our medical library here is a bit short of aerodynamic treatises :-). My limited knowledge of NACA submerged inlets is that there are design boundaries, but that there is a wide range of shapes that will work. At the sizes we're talking about here, I'd bet that 0.2" won't make a large difference - I think the most important thing is to keep the sides and bottom curvature smooth. No kinks, no corners, no tight radii. Anyone with more aerodynamic experience know more about this? -- Marc J. Zeitlin Email: marcz@an.hp.com From: Gary_S._Tiebens@ccmail.northgrum.com Date: Fri, 19 Apr 1996 14:31:29 -0700 Subject: Re: NACA Scoop Mark, I'm a Propulsion engineer for Northrop and have been in Inlet design and testing for 15 years. I have quite a lot of experience with NACA Submerged Inlets. W. Buckley is right, there is definitely some freedom in the planform dimensions, ie the width. What is most critical in the design of a flush scoop inlet is that the shoulder radii be as sharp as possible and that the ramp angle itself be as close as 7 degs as possible. In addition, the transition to the ramp should be smooth no tight radii. The incoming flow actually separates off the shoulder corners and forms two counter rotating vortices which in turn mixes high energy freestream flow with the local low energy boundary layer flow. I will be glad to fax you builders several reports that I have, but I will not be able to get to it until Monday the 22nd. Gary Tiebens ______________________________ Reply Separator _________________________________ Subject: NACA Scoop (fwd) Author: "Marc J. Zeitlin" at INTERNET Date: 4/19/96 5:26 PM William E. Buckley writes: >............. Knowing that the dynamics of the >NACA scoop are rather particular, I was wondering if I should make the >bulkheads conform to the NACA template or build the NACA scoop within the >shape already provided for by the bulkheads. Anyone else have this >problem and if so which is the correct shape? I had a similar, if not quite so disparate, experience. I figured that it was more likely for the scoop template to be correct than for the combination of bulkhead templates (not done on a CAD system) and idiosyncratic positioning (by me) to be correct. I widened or narrowed where necessary to match the scoop template. >.......... Does it really matter? I tried to search for NACA inlet scoop info on the WEB - found about a billion matches on ALTA VISTA and LYCOS, but no design detail :-). Our medical library here is a bit short of aerodynamic treatises :-). My limited knowledge of NACA submerged inlets is that there are design boundaries, but that there is a wide range of shapes that will work. At the sizes we're talking about here, I'd bet that 0.2" won't make a large difference - I think the most important thing is to keep the sides and bottom curvature smooth. No kinks, no corners, no tight radii. Anyone with more aerodynamic experience know more about this? -- Marc J. Zeitlin Email: marcz@an.hp.com Date: 19 Apr 96 20:27:10 EDT From: "William E. Buckley" <74744.2301@compuserve.com> Subject: NACA Scoop Again Neil Clayton asked about a convex bottom in his NACA Scoop. I'm not exactly clear on your question. So far all I've done is micro the urethane forward of the front LG BLKHD. I'll be sanding it down to shape tomorrow. If you mean the portion of the scoop bottom that is the fuselage bottom, it will conform to the slight curvature of the bottom and not be entirely flat. I haven't gotten to the portions aft of that. (Between the bulkheads). It would seem that those two sections will be flat and at somewhat different angles respectively. This would be a result of the differences in the depth of the cutouts in the bulkheads and bridging each gap with flat piecies of foam. Well, I guess I've beat this to death but at least this will give someone a chance to shoot me down if I'm all "hosed up". (Its a military term) But hey, its alot less painful than trying to un-hose something later on. William E. Buckley (COZY IV, #437, Chap 7) 74744.2301@compuserve.com Date: Fri, 19 Apr 1996 18:30:59 -0700 From: harvey3@ix.netcom.com (Neil K. Clayton) Subject: Re: NACA Scoop Again I was asking about curvature of the *bottom* surface of the NACA scoop. The forward section of the scoop will conform to the gently curving 3/8" foam base it was built-up on, but the plans dimensions dictate a continuing curvature of the scoop bottom as it proceeds aft. I was concerned that too much curvature will result in "negative lift" from this surface. A flat surface won't have any lift effect but this isn't the way it turned out. The flat surfaces with differing angles William refers to will generate a similar negative lift effect. Neil William Buckley wrote: > >Neil Clayton asked about a convex bottom in his NACA Scoop. > >I'm not exactly clear on your question. So far all I've done is micro the >urethane forward of the front LG BLKHD. I'll be sanding it down to shape >tomorrow. If you mean the portion of the scoop bottom that is the fuselage >bottom, it will conform to the slight curvature of the bottom and not be >entirely flat. I haven't gotten to the portions aft of that. (Between the >bulkheads). It would seem that those two sections will be flat and at somewhat >different angles respectively. This would be a result of the differences in the >depth of the cutouts in the bulkheads and bridging each gap with flat piecies of >foam. > >Well, I guess I've beat this to death but at least this will give someone a >chance to shoot me down if I'm all "hosed up". (Its a military term) But hey, >its alot less painful than trying to un-hose something later on. > >William E. Buckley (COZY IV, #437, Chap 7) >74744.2301@compuserve.com > > Date: Tue, 23 Apr 1996 09:53:01 -0400 From: Fritzx2@aol.com Subject: Ch 7 top longeron shaping/Ch 18 canopy hinge installation I remembered hearing from a fellow MK IV builder that he was displeased with the way the canopy hinges stuck out so far after carefully following the contouring instruction previously in chapter 7 for the sides near the top longeron. With this in mind, I first contoured the port side so that I could trial fit the hinges and make any corrections, if necessary, to the way I did the starboard side where the hinges are installed. After finishing the port side I can see now what he meant. Not only does the front hinge stick out really far in the front, but there does not appear to be enough hinge over top of the longeron to get a bolt down through and especially a nut and washer on the bottom anywhere near the front end of the front hinge. There is no dimension given for the location of the hinge attach screws to the fuse so I guess two screws located near one side of the hinge, a screw in the middle, and two more on the other end of the hinge is adequate. In trial fitting the two hinges, I placed them in a straight line relative to each as needed to prevent any binding. My question, then, has anyone had a similar problem and what did you do? My primary concern is the attachment of the hinge to the fuse. I could always build up near the exterior of the hinge when I install the turtle deck so that it blends in. From: Marc J. Zeitlin Subject: Ch 7 top longeron shaping/Ch 18 canopy hinge installation (fwd) Date: Tue, 23 Apr 96 12:22:40 EDT John Fritz (who did NOT use a signature in his message :-) ) wrote: >I remembered hearing from a fellow MK IV builder that he was displeased >with the way the canopy hinges stuck out so far .......... >My question, then, has anyone had a similar problem and what did you >do? My primary concern is the attachment of the hinge to the fuse. >I could always build up near the exterior of the hinge when I install >the turtle deck so that it blends in. Ugghh. That would be an unsightly bulge. Actually, on the COZY's I've seen, the hinge is noticible but not absurdly ugly. I've been looking at hidden cabinet hinges or the equivalent (the dragonfly hinges sold in the Wicks catalog, etc.) so that the hinges would be totally internal, and would lift the canopy away from the longeron as well. This might allow a better overlap of the canopy to the fuselage for wind and water sealing, as well as providing better aesthetics with no protruding hardware. Has anyone else done something like this? Aligning the hinges would be more difficult, but not impossibly so. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Wed, 24 Apr 1996 19:36:17 -0400 From: Jim Hocut Subject: Re: Hard Shelling - Delam Dick Finn wrote: > >You can draw your own conclusions from the above. I strongly advise testing it >yourself before using the hard shell method. > Been there, done that. I did some test layups using 2 plies uni @ 30 degrees (to simulate the glass orientation of the fuse bottom and sides). The only way I saw any problem with peel strength was when I didn't sand the hard shell before glassing it. With the test hard shell layup which I properly sanded adhesion was just as good as the "regular" layup (I didn't actually measure force, but I had to pull hard as hell to get the glass to come off, and in both cases it came loose with globs of foam attached). And (here's the good part) the hard shelled piece was slightly lighter than the "regular" layup (about 5% or so, your mileage may vary). With the peace of mind after performing this little investigation, I happily went about glassing my fuse bottom w/ the hard shell method. I did as suggested and laid out all the glass ahead of time, even used needle and thread to lightly stitch it together (great idea, thanks!!). Instead of spreading resin with a squeegee, I laid a sheet of clear visqueen out over the glass, and used a plastic paint scraper as a squeegee over the plastic. Works great for spreading resin without pulling the glass out of place, and you can really honker down to get any excess resin off to the side where it belongs (wasn't it the plans that said any excess resin is better left on your workshop floor than in your plane?). Anyway, from the time I mixed my first batch of resin to when I was finished with the entire bottom peel plied was only 80 minutes. Ain't no way I could have done that job myself using the traditional method. One thought on glassing the bottom and sides (too late for me, maybe it will help someone who's not to this point yet). The interface between the sides and bottom may come out better (and slightly stronger) by sanding a 1/16 inch deep by 1 inch wide recess along the length of the fuse (exactly like what is done at the front of the fuse). It's going to take a bit of filling and sanding to get a good looking intersection as per the plans. It's nothing major, but I feel like it would come out neater and save some work the other way. Jim Hocut jhocut@mindspring.com Date: Fri, 26 Apr 1996 09:31:59 -0400 From: william l kleb Subject: COZY: NACA submerged inlets sorry it took a while, but i finally managed to dig-up some old NACA reports concerning NACA submerged inlets. i am still going through them; but to respond to the current question of a curved ramp floor shape, i have transcribed some sections of text and scanned a few figures from one report which tested a curved ramp floor shape, the results can be found at: http://ab00.larc.nasa.gov/~kleb/naca/inlets.html the text without figures and hyperlinks is as follows: >From NACA RM A7I30: ... For each model four ramp planforms were investigated (fig. 3). Ramp angle could be varied from 5 degrees to 15 degrees. Figure 4 shows the geometric change of the ramp with ramp angle for one entrance configuration. Provision was also made for testing a curved ramp floor shape, with an entrance aspect ratio of 4 for ramp lengths which corresponded to the 5, 7, 9, and 11.5 degree straight ramp floors. This curved ramp floor, shown on Figure 5, represented the upper-surface profile shape of the aft portion of a 65-series low-drag airfoil. ... Table I is an index of submerged-duct-entry modifications covered in this paper. ... [Regarding the effects of a curved] ramp floor shape: A comparison of the pressure recoveries for the straight and curved ramp floors is given in Figure 15. The straight floor is seen to be superior for the configurations tested, but the difference in pressure recovery is small, usually less than 2 percent for the more optimum configurations. The present experimental results indicate this parameter to be of secondary importance in obtaining high-pressure recovery. Therefore, small changes in the contour of the floor that may be required to obtain a smooth junction between the ramp floor and fuselage skin should not noticeably affect the pressure recovery of the installation. ... The ramp floors for the aforementioned tests were all straight inclined surfaces. A comparison between the pressure distributions of the straight ramp floor and a curved ramp floor is given on Figure 24. The pressure gradient over the straight ramp appears to be more favorable for both parallel and curved divergent ramp walls. The reduction in pressure recovery which accompanied the more adverse pressure gradient of the curved ramp floor had been mentioned previously. It may also be seen that the straight ramp floor gives lower peak incremental velocities over the ramp than the curved ramp floor when divergent walls are used. The studies of ramp floor contour in the present investigation were limited in scope. A more fundamental study of the effect of the ramp pressure gradient on critical speed and pressure recovery will be made. The ramp floor should probably be designed so that the pressure gradient will have the least slope at the design inlet velocity ratio. ... End of excerpt. my two cents: from looking at Figure 24, i can't imagine much of a total lift variation on the airplane from a wavy ramp floor... --- bill kleb (w.l.kleb@larc.nasa.gov) 72 bellanca 7gcbc (citabria) 99 cozy iv -> aerocanard Date: Mon, 06 May 1996 20:37:17 -0400 From: Jim Hocut Subject: COZY: Ch. 7 - Side Contouring? Drawing M-16, section D-D shows the desired fuselage curvature at the firewall. The upper longeron is actually doubled at this point, which does not appear to be shown in section D-D. Is the reference arrow pointing to the inside of the doubler, or the inside of the longeron (i.e. in between the longeron and doubler)? Thanks, Jim Hocut Cozy Mk IV # 448 jhocut@mindspring.com Date: Tue, 02 Jul 1996 00:24:15 -0400 From: Jim Hocut Subject: COZY: Ch 7 & 9 - Landing Brake Once again my marriage to my project has hit a rocky spot in the relationship. I'd like to get a bit of input on an idea I had so that maybe others can benifit from my misfortune. While CAREFULLY prying the landing brake free from the fuselage bottom I pretty much destroyed it (the landing brake, not the fuse bottom thank goodness) because a good bit of epoxy had seeped underneath while doing the bottom layup. It dawned on me that instead of gluing down the landing brake with dabs of 5-minute, maybe we ought to be putting saran wrap or wax paper under it instead, to ensure that it doesn't face the same fate that mine did. The only thing we'd have to do when making the bottom layup would be to put a piece of plywood over the landing brake and weight it down in order to hold it in place while the layup cures (with proper provisions taken so the plywood doesn't become a permanent part of the layup). I might be missing something here, but from my experience it seems like this would be a whole lot easier in the long run. Jim Hocut jhocut@mindspring.com From: Paul.Krasa-1@pp.ksc.nasa.gov (Krasa, Paul) Organization: Kennedy Space Center, FL Date: Fri, 26 Jul 1996 13:00:21 -0400 Subject: COZY: Engine Cooling? I was wondering what the group thought of the NACA scope extention which is in the last issue of Central States. I'm not sure I understand how this could increase cooling since it does not increase the cross sectional area of the opening of the NACA scope. It sounds like it works but why? Paul Krasa Long EZ 214LP !---*---! Date: Fri, 26 Jul 1996 19:56:51 -0400 From: Jim Hocut Subject: Re: COZY: Engine Cooling? At 01:00 PM 7/26/96 -0400, Paul Krasa wrote: > >I was wondering what the group thought of the NACA scope extention which >is in the last issue of Central States. I'm not sure I understand how >this could increase cooling since it does not increase the cross >sectional area of the opening of the NACA scope. It sounds like it works >but why? > OK, I'm not an AE, but I think I understand this one (I actually manage to pick up a few tidbits listening to John Roncz and others @ OSH). It has to do with smoothing the transition into the cowling for the airflow. A smoother transition means less pressure loss (i.e. greater efficiency). This looks like an interesting idea, and I'm keeping it on my list of things to do. Jim Hocut jhocut@mindspring.com Date: Sat, 24 Aug 1996 18:00:01 -0700 From: Chris van Hoof Organization: C van Hoof - Architect Subject: COZY: Chap 7 questions Hello there, Having just started on chapter 7, I encountered a problem. The little plywood parts C & D dont't seem to be as accurate as the rest of the plan and now I'm doubting and checking all my work. Have checked all waterlines - OK - Fuselage centres nicely and shapes of bulkheads are accurate - working to a tolerance of max 1/16 inch. ______________ Part c |____________/ add L to R 1/4" | C / |__________/ reduce RH top by 1/4" and all this when the other dimentions are accurate ??? Part d is even worse if I locate same on firewall as per plan - it does not seem to be located exactly with dimentions - and of course if C gets altered D tries not to fit at all - The mitres then don't connect. Section :----------\ What is critical here - to keep mitre tight? -----------\ or to keep part D level between bulkheads? part D^ |\ | \ Part C needs adjusting as per above only if it part C>| | kept plum to inside face of longeron/fuse'side Your input & views will be appreciated - Thanx. Chris - # 219 cvh@iafrica.com T Date: Fri, 30 Aug 1996 09:42:37 -0400 From: Jim Hocut Subject: COZY: Repair Question In the process of moving my fuselage I apparently inflicted a wound that will need to be repaired (naturally it was my non-pilot non-builder helper that was moving the end that got damaged, but as PIC I'm of course responsible for the safety of the operation). I've got an area near the upper longeron just forward of the spar cutout that is disbonded (from approx FS 110 to FS 119). Will this area be visible on the finished plane? (This will, of course, determine how much effort I put into the cosmetics of my repair). Thanks, Jim Hocut jhocut@mindspring.com Date: 30 Aug 96 23:18:24 EDT From: "Edmond A. Richards" <103235.1336@compuserve.com> Subject: Re: COZY: Repair Question Jim Hocut writes: In the process of moving my fuselage I apparently inflicted a wound.... Jim, from your description it sounds like the area of the fuselage in question is the one that ends up in the fuel tank. As long as it's not below the spar cut out it probably won't show. However, I would make sure to repair it completely as a fuel leak is probably worse than a any cosmetic defect. My $.02 Good luck! Ed Richards Date: Sun, 01 Sep 1996 11:32:01 -0700 From: Michael Antares Subject: COZY: chapter 7 The question is : how deep (vertical) is the taper? does it go all the way to the longeron ? or only up to the little ears (triangles) next to the screws ? I've looked at every picture in the plans, newsletters and those I took at Osh 94 but can't seem to get a definite line. This is the one place in the plans where I actually had to call Nat. It IS confusing to say the least. The answer to your question is that the taper essentially ends at the ears. Speaking only for the way I did it (because others may have done it slightly differently) I continued the taper in a smooth way somewhat past the ears. At the bottom of the ears I have a thickness of approximately .15 of the blue foam. I tapered to the full thickness in approximately 3 1/2 inches from the bottom of the ears. I don't think it's very critical. I concentrated on getting a smooth curve at the interface of the blue and tan foam (where you have gone all the way through the blue foam and have exposed the tan foam). The strake fillet and sump area is going to cover most of this (I'm not that far yet so this is only surmise--others can concur or correct!). The one guide is that you obviously never want to go all the way through the blue foam where there is not an underlying tan foam nor would you want to leave an very thin section of blue foam so that implies that the tapering is done only where there is tan foam underneath. My two cents... 6077 Old Redwood Highway Penngrove CA 94951 707.664.1171 Cozy#413 Finished through chap 14 except chap 13. Chaps 16 & 24 mostly finished. Now on chap 19. Date: Sun, 01 Sep 1996 12:05:55 -0700 From: Chris van Hoof Organization: C van Hoof - Architect Subject: COZY: chapter 7 Fellow builders, Please spare me some time and help me with the following:- In Chap7, page 2, Step 2, line 5 before carving the corners, you should first taper the sides, from a point 25 in. forward of the firewall, back to the firewall. .... My fuse is upside down and the corners are sanded up to the front of the landing brake... the 25 in line is marked out and I even found the firewall (perm installed). The question is : how deep (vertical) is the taper? does it go all the way to the longeron ? or only up to the little ears (triangles) next to the screws ? I've looked at every picture in the plans, newsletters and those I took at Osh 94 but can't seem to get a definite line. Thanks in advance - eagerly awaiting your input |<25 in |------|_______|-------------------- | | | tapered area - Size ? =|______ | | SIDE ELEVATION _______| =|___________________________________ chris cvh@iafrica.com Date: Tue, 03 Sep 96 08:01:42 EST From: MISTER@neesnet.com Subject: Re: COZY: Repair Question Jim Hocut writes: >>I've got an area near the upper longeron just forward of the spar cutout that is disbonded (from approx FS 110 to FS 119). Will this area be visible on the finished plane? << As I recall, that area will be inside your fuel tank in the strake area when finished. You'll want to make sure that it's fuel proof. Bob Misterka N342RM ______________________________ Reply Separator _________________________________ From: Marc J. Zeitlin Subject: COZY: Chap 7 questions (fwd) Date: Tue, 3 Sep 96 10:50:33 EDT Chris van Hoof writes: >Having just started on chapter 7, I encountered a problem. >The little plywood parts C & D dont't seem to be as accurate as the rest >of the plan and now I'm doubting and checking all my work. I had the same problems with C &D. Don't sweat it - these are basically just support for the foam filler pieces around the gear legs, as well as tie-ins for the bulkheads to the sides. If I remember correctly, you flox these in (and the flox can easily fill any voids) and then you will glass over the inside in Chapter 9, as well as adding foam and glass over the outside later in Chapter 7. I just sanded them to fit reasonably well, and filled any voids in the joint with flox. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Wed, 04 Sep 1996 12:15:26 -0700 From: Chris van Hoof Organization: C van Hoof - Architect Subject: COZY: Chap 7 Hi to all and thanx for the info you shared. Still in my playbox, busy on chapter 7, and found another question. The bottom of the fuselage is about to be covered, of course the plans are being followed, maybe I read between the lines, :) The 3/8 in foam is installed between the firewall & aft gear bulkhead, since this went so well, I installed Urethane foam over this little lot, thinking this gets glassed at the same time.....does it? The pic's in the gear chapter show an unfoamed/unglassed section behind the gear. Since I allways seem to see / read more than others (:-))which is the route you have taken?....and is there any disadvantage to doing it now? TIA chris #219 cvh@iafrica.com Date: Wed, 04 Sep 1996 12:30:46 -0700 From: Chris van Hoof Organization: C van Hoof - Architect Subject: COZY: chap 7 Hi, To all those starting on this chapter. Here you will learn about antennae - all you wanted and then some. Just to save some time - there is talk (lots) about FERRITE TOROIDS and plenty of referral to same, and they must be "matched" or of the correct "value", etc. etc.... What this means is (says the local chapter radio guru) that this is for the frequency to be used, ie 118 to 136Mhz. Hope this saves you looking this lot up, it was not obvious to me.... amazing things radios. :) . NO, I can't answer questions, but let me know your answers, thanx. chris #219 cvh@iafrica.com Date: Tue, 17 Sep 1996 10:21:39 -0400 From: Jim Hocut Subject: Re: COZY: Layup > >then to add injury to stupidity, in the daylight saw that an area about 1 >square foot was not wetted out enough... it sort of sparkles in the >reflection without being hollow or dry??? Just my .02. Hard to give an opinion without actually seeing the layup in question, but it kind of sounds like merely a surface phenomena you are seeing. I've noticed the same type of appearance (I think) as you describe when the peel ply isn't fully wet out. If that's the case it's merely cosmetic and not a problem, you'll just deal with it when you get to the finishing. (I'm sure someone would be glad to offer a more thorough opinion if you want to cut out the area in question, foam and all, and mail it to them ). Jim Hocut jhocut@mindspring.com Date: Tue, 17 Sep 1996 09:41:10 -0700 From: Chris van Hoof Organization: C van Hoof - Architect Subject: COZY: Layup Hi Cozites, Hope you all had a great weekend, mine was untill the checks were being done, what a mess, gets me almost into a depression... Did the exterior bottom layups and thought I was carefull, found some air trapped at the front (f22) which was fixable, but found some large bubbles under the landing gear reinforcing strips near the corners - must have happened during peelply, about 1/4 to 1/2in by 1.5in. then to add injury to stupidity, in the daylight saw that an area about 1 square foot was not wetted out enough... it sort of sparkles in the reflection without being hollow or dry??? Need you comments on the following please. will do Rutan repair to the landing gear reinforcing but remove the whole reinforcing strip & redo same. Long this bubbles near F22 in the 1/16 recess were fixed with injection needle while layup was at its last "tackyness" The sparkling area : Thought of adding one ply twill weave bidirectional over the complete area which is 4" behind the instrument panel to about 4" in front of the landing brake. The sparkling area is only on the LH of the centre line Thanks in advance. Chris #219 in my playbox with Cozy on chapter 7 cvh@ iafrica.com From: "Krasa, Paul" Subject: RE: COZY: Strake Windows Date: Wed, 25 Sep 1996 03:08:22 -0400 Nick Ugolini said >... I would recommend placing a window in the floor of the the rear >seats. I have seen Herb Sanders Long EZ which has this modification, and I like it. The trade off is you have to delete the landing brake. Paul Krasa Long EZ 214LP > > > Date: Mon, 28 Oct 1996 12:12:14 +0000 From: Rob Atencio Subject: COZY: Chap 7 - Flange recessing Got a question for those of you ahead of me in building. I have gotten to the portion where a recess is cut out around the L/G bulkheads for the L/G cover. The plans say to make this recess and it is shown on drawing M-9. Now for my question. Is a similar recess needed at the firewall where the cowling will attach? The cross section on M-9 indicates a slight recess in this area but it doesn't look to be as deep as that for the L/G cover. However, nothing is mentioned in the plans about recessing this area. Even if it's not called for, would it be a good idea to add this feature for later attachment of the cowling? Thanks for any input. -- Rob Atencio Cozy MkIV - Chpt 7 New Bern, NC ratencio@coastalnet.com Date: Tue, 03 Dec 1996 12:05:45 -0500 From: william l kleb Organization: NASA Langley Research Center Subject: COZY: electric landing brake i have just decided to go electric. i am preparing to glass the exterior fuselage bottom and am wondering if there are any extra plies or hardpoints i should install in anticipation of wayne lanza's set-up? (i haven't placed the order yet.) thanks, --- bil kleb (w.l.kleb@larc.nasa.gov) 72 bellanca 7gcbc 9? cz4 -> aerocanard Date: Tue, 03 Dec 96 11:35:00 PST From: Brian DeFord Subject: Re: COZY: electric landing brake >i have just decided to go electric. >i am preparing to glass the exterior fuselage bottom and >am wondering if there are any extra plies or hardpoints >i should install in anticipation of wayne lanza's set-up? >(i haven't placed the order yet.) >thanks, Bil, Nothing external is different, however, when you cut your brake free you should move the plywood hardpoint that the bracket bolts to. Wayne's instructions are clear on this. You will also be modifying the hole locations for the bracket since the arm mechanism is larger in diameter than the plans arm. Brian DeFord, MK-IV #309 Date: Mon, 16 Dec 1996 07:24:01 -0500 From: william l kleb Organization: NASA Langley Research Center Subject: COZY: chap 7: glassing the sides when glassing the bottom exterior, the plans specifically mentioned overlapping the ends 2" on f22, the LG bulkheads, and the firewall. for the sides, i can't find any mention in the text about overlaps. figure 23 indicates "knife trim" at f22, but shows nothing for the firewall. any recommendations? --- bil kleb From: Marc J. Zeitlin Subject: COZY: chap 7: glassing the sides Date: Mon, 16 Dec 96 9:21:24 EST bil kleb writes: >for the sides, i can't find any mention in the text about >overlaps. figure 23 indicates "knife trim" at f22, but shows >nothing for the firewall. any recommendations? Since you really only need a good 1/4" of overlap (at most, in a perfect world, which this isn't :-) ) to get a good joint, I usually make my overlaps 1" when it doesn't say what to do. I figure this is a good safety factor in case my joint isn't perfect, and it doesn't add much weight. Plus, it's the standard overlap for all 2" BID tapes. YMMV. -- Marc J. Zeitlin Email: marcz@an.hp.com Date: Mon, 16 Dec 1996 19:30:00 -0500 From: Paul Burkhardt Subject: COZY: firewall overlap figure 23 indicates "knife trim" at f22, but shows >nothing for the firewall. any recommendations? AS I recall the firewall isnt installed at this point and you simply end the glass at the end of the foam flush. I think you wrap a tape around after the installation of the lower firewall. Its been a while so my memory might be off a bit. Paul Burkhardt Date: Tue, 17 Dec 1996 10:42:16 -0500 From: william l kleb Organization: NASA Langley Research Center Subject: COZY: chap 7: rotisserie am i missing something? i don't understand the need for the a-frame rotisserie set-up for glassing the exterior fuselage sides. i just set the beast on some towels and it seems perfectly stable. is there some other reason for creating this extra "jig"? --- bil kleb Date: Tue, 17 Dec 1996 11:19:04 -0500 From: Jim Hocut Subject: Re: COZY: chap 7: rotisserie >am i missing something? i don't understand the need for >the a-frame rotisserie set-up for glassing the exterior >fuselage sides. .... It's WAY easier to get the fuselage in just the right position by having it on a rotisserie. There's also much work to be done inside the fuselage in later chapters that will be made easier by being able to rotate the fuselage to whatever position you desire. I'm jumping around in the plans so that I can do as much work as possible with the fuselage mounted like this instead of having to stand on my head to put in a tape joint or whatever. Jim Hocut jhocut@mindspring.com Date: Tue, 17 Dec 1996 11:43:02 -0500 From: william l kleb Organization: NASA Langley Research Center Subject: COZY: chap 7: joggles maybe i'm off on a tangent, BUT: i have seen, or heard of, people who go to great lengths trying to get the glass fabric to conform to sharp corners created by joggles. since chapter three specifically states that corners are to be rounded for structural reasons and even gives minimum radii to use for bid and uni in various orientations, why can't the beginning of the "joggle" be tapered or slightly rounded? eg, like this: ________ \ \ \_________ instead of the abrupt shape change of, __________ | | |_________ it seems that you would end up using slightly more filler, but you would lose the frustration of trying to get the glass to conform to such an impossible shape... maybe the filler poses a durability problem in areas like the landing gear cover or the landing brake? however, for other areas that evidentually become part of a glass-to-glass overlap, it shouldn't make any difference; and in fact, the tapered joint should develop more tensile strength since the fibers aren't bent as much. comments solicited. --- bil kleb by SERV05.SLAC.STANFORD.EDU (PMDF V5.1-4 #16063) with SMTP id <01ID472IDKXY000DAZ@SERV05.SLAC.STANFORD.EDU> for cozy_builders@hpwarhw.an.hp.com; Tue, 17 Dec 1996 12:14:42 PST Date: Tue, 17 Dec 1996 12:16:54 -0700 From: hrogers@SLAC.Stanford.EDU (Howard Rogers) Subject: Re: COZY: chap 7: joggles snip > >since chapter three specifically states that corners are >to be rounded for structural reasons and even gives minimum >radii to use for bid and uni in various orientations, >why can't the beginning of the "joggle" be tapered or >slightly rounded? Bill, I think you have done an excellent job of correctly answering your own question! > >it seems that you would end up using slightly more filler, >but you would lose the frustration of trying to get >the glass to conform to such an impossible shape... > >maybe the filler poses a durability problem in areas >like the landing gear cover or the landing brake? In areas like this, I have taken the liberty of substuting flox, if I think a durability issue is present. I have even used a combination of flox and micro, on a "judgement call", where a great deal of strength isn't required, but micro would be just a tad vulnerable to crush or wear, later. I know that no such mixture is called for in the plans, but I always try to err on the conservative side *AND* try to save weight. >however, for other areas that evidentually become part >of a glass-to-glass overlap, it shouldn't make any difference; >and in fact, the tapered joint should develop more >tensile strength since the fibers aren't bent as much. Right on! --Howard Rogers, 415-926-4052 hrogers@slac.stanford.edu From: Marc J. Zeitlin Subject: COZY: chap 7: joggles (fwd) Date: Tue, 17 Dec 96 15:14:48 EST bil kleb writes; >why can't the beginning of the "joggle" be tapered or >slightly rounded?..... >maybe the filler poses a durability problem in areas >like the landing gear cover or the landing brake? These are the only two areas (along with the NACA scoop) that I can remember trying to get the severe joggle to which you refer. I think that having very thick filler without glass over it is asking for flaking, chipping, and chunking in the future (unless you put a very light glass layer over it). The strength in these areas isn't critical. -- Marc J. Zeitlin Email: marcz@an.hp.com