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Fuselage Stretch?

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Will V

Well-Known Member
Jan 8, 2007
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As I bide my time until I can afford to build an aircraft (and figure out which one I should build), my mind often wanders to the Knight Twister Co-ed plans I have sitting in the corner. Then I have some questions that perhaps other builders wonder as well. I am hoping someone of the engineering persuasion (Kevin?) can wade into the waters and offer some generalize opinion or advice.
I have yet to mock up the plan cockpit dimensions but if I see a need to stretch the cockpit a few inches between bays for comfort, what are the implications to a tubular fuselage’s strength? For instance the Twister Imperial of Don Fairbank’s was stretched several inches (14”?) with the designer’s approval to improve visibility in pylon racing. What I’d like to know is: would stretching the fuselage 4 or 5 inches in one or two of the bays affect the strength of the fuselage structure much? (Is the strength more from the separation of the longerons than the spacing of the verticals and diagonals?) Also, along the same vein, is widening the fuselage an inch or two a big deal? I don’t know if I’d want or need to do any of these modifications but it’d be good to know ‘where to get off the bus’.
While investigating Lynn William’s 2 place Flitzer design, the dimensions he provided for the cockpits are almost identical to the Co-ed’s and he claims his aircraft will accommodate a 6’-2” person like myself. So my questions may be moot.
I realize there are CG considerations but without a Twister Coed being completed, who’s to know if the plan dimensions are going to work as expected anyways. It may be so tail heavy that one may have no choice but to hang a 540 up front (!?!)….. then that would lead to more questions… Of course I could do like everyone else and wait for someone to make all the ‘mistakes’ with their Twister Co-ed first. John C. that may be you!(you know who you are- how’s the CNC wing parts coming?) We’ve been waiting a long time and it looks like no one else is biting…Which is why I think this may be best as my second (!) build project, not a first.
And then in the back of my head I keep remembering the saying that those who go on and on about the mods they are going to make generally never build or complete an aircraft….so I’d like to stick close to the plans of what ever I finally do build!
P.S. Have any of you Florida guys been able to go check out Hale’s old Twister and get some detail pics?

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