Date: Wed, 24 Jan 96 18:29:29 est From: "Larry Schuler" Subject: cabin width I am new to the mailing list; new to cozy (just finished building my shop). Materials through chap 8 on order. Hope to widen cabin front seat 3" - 4" and back by 2" to 3". Also will need to raise the canopy about 2". I am 6'4" @ 200#; not "Big" (as in wide) per-se. However, I was able to sit in Nat's Cozy at Oshkosh and found that my shoulder rubs hard on the edge. Bothered me enough to be concerned about getting beat up in rough air. Here are primary concerns: 1. Stress at landing gear attach and engine attach. 2. Fire wall/fuselage attach/stress. 2. Strake/wing attach and stress. 3. Center spar attach. 4. Airflow separation aft of the cabin due to too quick a curve. I see no problem with the width alone other than slightly more wetted area and flat plate area (drag). Aero plastics folks said it's do-able both height and width for canopy. Little less fuel??? Thought about doing a mock-up in wood, then found this mail-list. Many of you have been building for a while and I havn't quite started. I would appreciate any input, suggestions, thoughts, scoldings, warnings, or whatever. Some of you have a good handle on what the fuselage looks and feels like (sitting in your shop); I don't yet. Any structural/stress engineers out there? Thanks, Larry lschuler@cellular.uscc.com Date: Thu, 25 Jan 96 09:07:10 EST From: "Wilhelmson, Jack" Subject: Re: cabin width Larry: I have some theoretical data on the forces, stress, and deflection under load for the engine mount attach points. I have been working on the stress analysis of the PZL350\Franklin engine mount design for NAT. This data shows that the design has extreme safety factors, even for aerobatic loads. I do not have any of the other data you ask about. The manhrs required to do even simplified analysis is more than I have to spare. However, my opinion is that the airplane is basically over designed. What you should consider is the gross landing and takeoff weight, and what the performance of the brakes and other support systems will be. Another consideration is the redesign time that will be added to your building time. Date: Thu, 25 Jan 1996 09:10:07 -0500 From: william l kleb Subject: Re: cabin width Larry Schuler writes: > I am new to the mailing list; new to cozy (just finished building my > shop). Materials through chap 8 on order. > i am roughly in the same situation... > I am 6'4" @ 200#; not "Big" (as in wide) per-se. However, I was able > to sit in Nat's Cozy at Oshkosh and found that my shoulder rubs hard > on the edge. > i had the same experience: i am 6'3" at 185. i was "just" going to widen the firewall by 3" and taper to the standard front seat-back width, so that the rear seat has some more room and i can make full use of the aerocanard turtleback. this essentially will make the plane an aerocanard since this widening is really the only major difference between the planes. the aerocanard turtleback gives you extra shoulder room since it is molded with a constant skin-thickness, and consequently, isn't built-up near the edges as for the plans-built cozy turtleback. the difference is ~3" at the shoulder. jeff russell sold me the aerocanard bulkhead templates so that i can be assured of a turtleback fit--although i am now thinking that additional butt-line measurements along the top longerons would greatly aide that purpose. at oshkosh, i spoke with nat about the canopy height and he said that it was an easy mod and that i should speak with vance atkinson about it-- something i haven't done yet. however, i believe you actually get 2" more headroom with the aerocanard turtleback alone. see mark turners page: http://www.windev.com/AeroCanard/ for aerocanard/cozy iv comparison info. there are at least a couple others considering these types of mods. i have heard through the grapevine that one individual is widening the entire fuselage by 6"!---too bad that experiment hasn't flown yet. > Here are primary concerns: > > 1. Stress at landing gear attach and engine attach. > 2. Fire wall/fuselage attach/stress. > 2. Strake/wing attach and stress. > 3. Center spar attach. > 4. Airflow separation aft of the cabin due to too quick a curve. it seems that these are the same concerns that nat had to deal with when he went from a long-eze to a cozy in the first place---or rutan when he went to the defiant (which, from what i understand, is where the rear of the cozy iv comes from). i see the slight widening of the fuselage to be a rather small perturbation in comparison. i was actually more worried when i heard the spar thickness was increased 20% from the cozy to the cozy iv! the standard beam-bending stiffness equation goes as thickness^4---so this simple analysis says the wing spar is 2 times stiffer! a stiffer wing is not always better since the wing root moments can now be much higher since the wing is not able to "unload" lift through deflection. --- bill kleb (w.l.kleb@larc.nasa.gov) 73 bellanca 7gcbc citabria 99 kleb cozy iv Date: 25 Jan 96 10:44:50 EST From: Rick Roberts <102503.1561@compuserve.com> Subject: Re: cabin width I'm sorry for forwarding alot of this message but there are a lot of points in it and I think I can help with. I am building a "King Kozy" 6" inches wider, bigger engine, higher gross wt, retracts (Infinity), etc. etc. My partner and I are both way big by the Gnat definition in newletter #52. 6'1" 230 ish and when we started our project we sized it for both of us in front and both of our wives in back plus baggage and fuel. The numbers can all be made to work out. Anyway after sitting in my brother in law's mostly stock (size-wise) Mark IV, I concluded that the we made the right choice early. At my size and width I couldn't even sit centered in the seat, I do cave exploration for fun and I felt clousterphobic (a horrible spelling job). Anyway the change is significant, but it really doesn't add too much weight 10-20 pounds if all you do, however, you must design your own canopy and engine shrouds, as Nat doesn't bother to give you sections on the engine shrouds. Anyway if you saw my fuselage next to the standard one it is amazing how much bigger it is! It is wonderful. The final comments that Bill Kelb had considering the analysis of the spar, strake, etc. Our analysis said that the Mark IV design was a no problem situation. The spar is a massive structure. Also the root area of the wing is one of main areas that was beefed up, probably but I wouldn't count on it, (not much analysis ability with the Nat) to account for the increased wing root moments. Anyway, the cats out of the bag, for what it is worth. Rick Roberts Date: Thu, 25 Jan 1996 17:59:10 -0500 From: Phillip.Johnson@Lockheed.on.ca (Phillip Johnson) Subject: Re[3]: Cabin Width Larry It has nothing to do with cabin width other than my response was relating to Bil Kleb's response that was related to Cabin width. It's a pretty tenuous link I know. Sorry. You are actually in much the same category as many of the builders. I wish I had done the same as Rick Roberts, I've seen that project once and it looks good. I started building strictly according to the book but I found a lot of nonsense so I've made a number of departures. My Canopy is wider than Nat's, I had Airplane Plastics make me a special at no extra cost. The arc, when viewed from behind is 4 inches greater than the standard and I added a further two inches in the frame. The whole canopy is two inches higher and the plastic runs close to flush with the edge of the fuselage . I'm 6ft 3in and weigh 230 lbs and I am long in the body not in the leg so I would hit the canopy with my head in the standard configuration. I flattened the canopy top a little so the section through the canopy is elliptic rather than round, major axis horizontal. My shoulder can now rest against the longeron without my head hitting the canopy even with phones. The canopy hinges forward so its a little safer, i.e. it can't open significantly in flight and you get rid of that awful hinge on the side. Furthermore passengers may alight with the pilot in place. My turtle back is commensurably wider and runs down the total length of the longerons. I have included a gull wing door into the turtleback to allow entry to the rear seating compartment. My engine cowlings flow on from the turtle back so there are no bumps or protrusions. It's probably more aerodynamically clean than Nat's but I think that the lines of Nat's may be slightly more attractive, being lower. I had to weigh comfort against looks. Widening the fuselage will marginally increase the strength of the canard and the main spar simply because the attachment points are closer to the ends but the significance is pretty small. The overall weight change of a few pounds is insignificant since everyone comes in at a different weight anyway. Some Cozy's are loaded with avionics which makes them heavy, others have auto engines and others have retractable main gear. There is some freedom to manoeuvre but at the end of the day you have to fly within the same weight and balance envelope if you do not wish to become a full blooded test pilot. We are all going to be a test pilot to some degree depending on the adherence to the plans. Phillip Johnson ______________________________ Reply Separator _________________________________ Subject: Re[2]: Cabin Width Author: "Larry Schuler" at smtp_gway Date: 25/1/96 3:59 PM Phillip, I see your point; but, what does this mean for added cabin width???? Will I need to add another layer of glass on center spar for the additional weight? (SWAG'ed at this point to be about 10 to 20 lbs.). And if I do, that adds weight...................etc. Larry _ Date: Fri, 11 Oct 1996 12:42:30 -0400 From: SMilesCozy@aol.com Subject: COZY: Wider, Deeper Fuselage Has anyone contemplated or attempted to widen and/or deepen the fuselage by using either thicker foam and/or more layers of thin foam and contouring or carving it into an oval shape, thereby increasing elbow room without changing longeron locations? As a side note, how much extra drag will an oval have, that encompases all four corners of a box, than the box??? Just thinking out loud Steve Miles Cozy MkIV 272 Date: Fri, 11 Oct 96 13:12:11 est From: "Larry Schuler" Subject: COZY: Wider, Deeper Fuselage Steve Miles wrote: >Has anyone contemplated or attempted to widen and/or deepen the fuselage by >using either thicker foam and/or more layers of thin foam and contouring or >carving it into an oval shape, thereby increasing elbow room without changing >longeron locations? I assume you mean an oval in the vertical plane, top to bottom; rather than horizontally front to back..... I did think about this some, but seemd like the fuselage side jigs would be a real pain to make. Relatively flat is easier than reletively round..... Also, when I sat in Nat's Cozy, my shoulder hit the top longeron, so I noticed this more than the elbow room; I opted to take care of both by widening fuselage evenly on both sides of BL-0. My .02 worth. >As a side note, how much extra drag will an oval have, that encompases all >four corners of a box, than the box??? Frontal area is bigger, and wetted area (more surface) is greater. As for calculating "how much extra drag": maybe there's an AE on line here who is willing to do the calc for you, but I'll wager you would need to look up the formulas and make a stab at it. >Just thinking out loud Me too. :-) Larry Schuler MKIV-#500 ch-6 (just about to do the fuselage flip) [that's not the name of a dance.... unless I drop it on my foot] :-).