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42% design help

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Old 12-14-2004, 09:27 PM
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aubie
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Default 42% design help

I have had a set of Hostetler 42% giles 202 plans for a few years now and I retrieved them out of the closet a few nights ago and started doing some thinking. What I have in mind is converting it into a 42% profile plane. The fuse would be flat sided and narrowed to 6 inches wide. This would be from the nose of the plane back 42 inches then it would narrow to a final width of 2 inches. The projected weight would be between 21 lbs to 24 lbs and the engine choice would be a zenoah 80. I will be usuing all the original dimensions on the fuse but my question is will I run into CG issue making the above mentioned change and with the proposed engine.
The wing panels would be extended from 48 inches in length to 53 inches for a wingspan of 112 inches. I have them planned with foam cores instead of built up, the usual sheeting and cap strip method. I will probably remove the foam between the cap strips via hot knife. The rudder and elevator will be fully sheeted. The next question is how do I get a little more out of the controll surfaces. I realize that this will be a 42% plane but I would like it to how somewhat of a profile agility. I see two options which are go for double beveling and going for 60% control surface movement or move the hinge lines forward and shooting for 45% of throw. I will be usuing JR 8611 servos on all surfaces.
I realize that this is a bit far fetched but it will make for a good winter project. Please fell free to chime in with any and all info that would be helpful.
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Old 12-17-2004, 07:53 AM
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Default RE: 42% design help

You'll get more throw by increasing the angle you build into the hinge lines of the surfaces. Maybe use a little thicker balas there, and sharpen the angles up.

I assume you're making the profile fuse from foam as well, and sheeted? Don't forget some hardwood stringers in there, to tie the engine box back to the main wing spars/tube.

The CG should not change at all with the profile fuselage. It should be in the same place as the plans dictate. You may have to move equipment around (forward) with the lighter engine.

Also when considering this project, the amount of drag a large airframe like this is going to generate. With over 2000 squares of wing, it's going to be a little slower.

phil in georgetown
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Old 12-17-2004, 11:36 PM
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Default RE: 42% design help

Thanks Phil. I understand that the cg will be the same as before but there is a big diffrence between the weight of a 240 cc engine apposed to an 80 cc engine. That is what I am concerned with. I can move the wing back further but I have no idea how far to move it to correct the problem. The other alternative would be to shorten the length of the fuse. This would help with the performance that I am looking for but it also leads back to the concern stated above. How much?

The profile fuse will be built up. Light ply fuse sides with ply doublers and formers. Removeable top hatch for radio access.
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