Narfi's Zenith CH750 Super Duty

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narfi
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Re: Narfi's Zenith CH750 Super Duty

Post by narfi »

2.5hrs
Made the form and cutting blocks for the wing root ribs and ground out the fluting grooves in it and the nose rib blocks I had forgot to grind them into.

The root ribs top flange goes from 60° at the nose to 90° at the rear spar. I puzzled over best way to do that and decided to just make the forms like all the others and free handedly not beat it down all the way at the front. As easy as cutting out and bending is once the forms are made, I can try a couple if I mess up one or two, and I only need a good left and a good right, so not worth trying to overthink the formers..... We will see :)
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Total time spent building: 47 hours
Total Cost: $8276
Airplane + consumables + project specific costs: $5340
Tools, etc.. I will keep for future projects: $2936



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narfi
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Re: Narfi's Zenith CH750 Super Duty

Post by narfi »

0 hours
Went to start building the rear bulkheads last night and found a contradiction in the dimensions, so called it early and binge watched some shows my son was wanting to watch.

Called Roger this morning and he is looking into it as well as more parts for me to build.
Anyone know what scratch builders are doing for the tips of the flaperons, slats and wings? they all seem to be plastic or fiberglass parts. Just thinking ahead....

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narfi
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Re: Narfi's Zenith CH750 Super Duty

Post by narfi »

2hrs.
Made the cutting and forming blocks for the two rear bulkheads. Could have probably freehanded them in less time, but if I mess one up during assembly and need to remake one, or inevitably damage one during the life of the plane, it will save me time in making a replacement and be a "quick" simple fix.
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Total time spent building: 49 hours
Total Cost: $8276
Airplane + consumables + project specific costs: $5340
Tools, etc.. I will keep for future projects: $2936

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Netpackrat
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Re: Narfi's Zenith CH750 Super Duty

Post by Netpackrat »

Most if not all of the Bearhawk scratch builders used fiberglass for the wing tips, built one off over male molds. Prior to the advent of the quick build kits, there was a builder who made a more production oriented mold, and he sold sets of tips to other builders. No reason you couldn't do them out of aluminum, but the skills required are not common. Basically you make a male "buck" the shape of the tip, and then form to fit from sheet, welding as necessary.

This is a fender in steel rather than a wing tip in aluminum, but the basic process is the same. Biggest difference is you would probably be making an upper and lower half joined by welding at the ridge of the buck.

https://www.youtube.com/watch?v=Ktj5DWaKXYI

https://www.youtube.com/watch?v=lYK8Tn3uNaI

He relies pretty heavily on the English wheel, but it's not the only way. Building an all aluminum aircraft, there is something pretty special about having wing tips and other fairings also of aluminum rather than glass, but the tangible benefits don't really outweigh the difficulty.

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narfi
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Re: Narfi's Zenith CH750 Super Duty

Post by narfi »

@Netpackrat Fiberglass one off seems to be the way I am leaning, at least for now......

Friday the last of my aluminum came in and my wife helped me unroll and put it in the rack.
I went threw my drawings to see which pieces to leave out on the table for the next parts and discovered a huge mistake I had made.
The rear wing ribs are supposed to be .025 and I had made them from the same .016 as the tail ribs.........
In all it's not a huge setback, a couple hours of work and 2/3s of a sheet of .016 aluminum wasted. If that's the worst mistake of the project ill be happy ;)

4hrs friday night cutting all new rear wing rib blanks, nose ribs, and root ribs (all .025 this time) and the two rear fuselage bulkheads(one is .040 and one is .032)
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(Not counting the bulkhead parts, that is a full 4x12 sheet of .025 shown in the picture, all wing ribs from one piece)

2.5hrs and 3.5 hrs Sunday bending them all. 2 bulkheads, 14 rear wing ribs, 20 nose ribs, and two sets of two root ribs. The wing ribs are a larger front radius but it felt like the .025 forms better than the .016 on the tail pieces, the thinner stock wanted to fold more while the thicker could be (pushed around) easier with a brass hammer.

My boy even came out to help bend some of the parts which made me proud.

I had one flute crack out so needed to make one extra rib, but not bad for the mass production over the weekend.

Just need to cut and flange all the lightning holes.

That's all the parts I have from Roger to build so far, he is working on getting me the rudder drawings next.
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Total time spent building: 59 hours
Total Cost: $8276
Airplane + consumables + project specific costs: $5340
Tools, etc.. I will keep for future projects: $2936

fallguy1000
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Re: Narfi's Zenith CH750 Super Duty

Post by fallguy1000 »

Wow, serious fun, but serious QA demands.
My boat build is here -------->

viewtopic.php?f=12&t=62495

Jeff
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Re: Narfi's Zenith CH750 Super Duty

Post by Jeff »

Nice work Narfi & Landon!!!! Jeff

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Netpackrat
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Re: Narfi's Zenith CH750 Super Duty

Post by Netpackrat »

Good that you are catching your errors, stinks about the wasted material given the logistics of getting it out there. Back when I was still going to EAA chapter meetings occasionally, there was one held at the home of a guy who was finishing up a Pietenpol Aircamper build which he had on display in his front yard. I spotted a cracked wing strut fitting which I pointed out. 8O. Insufficient relief at the corner of a bend IIRC.

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narfi
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Re: Narfi's Zenith CH750 Super Duty

Post by narfi »

1.5hrs cut the lightning holes in all the ribs, nose ribs and root ribs. Need to clean them up and flange them now.
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Total time spent building: 60.5 hours
Total Cost: $8276
Airplane + consumables + project specific costs: $5340
Tools, etc.. I will keep for future projects: $2936

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