Narfi's Zenith CH750 Super Duty

[Jeff]

Nice work Narfi!!!! Jeff

[narfi]

It has been pretty cold this last week, cold enough to keep me from working out in the tent but it significantly warmed up to around 25-28ish F which is warm enough to get our first snow to stick for the winter.

I was able to take off my jacket and just wore a thick sweatshirt with a labcoat over to keep most of the dust off.

2 more hours got the cutting templates and form blocks done for the rear wing ribs.

My wife came out and helped me unroll the aluminum and get it into the rack. Left out a sheet of .016 to start cutting up as well as the .020 I have already cut into. I had made the two stabilizer end ribs, but for the superduty there are actually 2 end ribs on both sides as the forward spar doesn't extend to the tip.

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Total time spent building: 24 hours
Total Cost: $8276
Airplane + consumables + project specific costs: $5340
Tools, etc.. I will keep for future projects: $2936

[Jeff]

Nice work Narfi but 25 is still way too cold for me!!! Jeff

[narfi]

Nice work Narfi but 25 is still way too cold for me!!! Jeff

hehe, its perfect..... any warmer and you can't stay dry, colder and you need more layers than are convenient for working.(non manual labor)

[narfi]

hehe, its perfect..... any warmer and you can't stay dry, colder and you need more layers than are convenient for working.(non manual labor)

It got warmer :/ nasty wet weekend, now we have icy mud



About 10 more hours this weekend got some visable progress.
Cut out and bent two more stabilizer end ribs since each side uses 2 instead of one with the partial length spar. Then cut and bent all the rest of the horizontal and elevator ribs as well as the rear wing ribs.
Still need to cut and flange the lightning holes in the wing ribs, tool kit that has the hole cutter from aircraft spruce is still backordered so may end up with another ghetto set-up since it worked so well making the dies.
1/4" end bearing router bit is supposed to get here from amazon this week, tracking says it was in state Friday. Then I can cut out the slat and flaperon ribs, they are smaller peices with tighter radius flanges so the 3/8" I have been using is too big for them.

The cutting and bending of all the ribs went very quick and easy imo, I probably spent more time making the templates and forms, but well worth the time and effort, I am quite pleased with how they look. (Esp. Knowing how much(textron?) Piper, Cessna and Beech charge for each little peice :p

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Total time spent building: 34 hours
Total Cost: $8276
Airplane + consumables + project specific costs: $5340
Tools, etc.. I will keep for future projects: $2936

[Jeff]

Very cool Narfi!!! Jeff

[narfi]

About 3.5hrs in the tent.
Cut the lightning holes in all the rear wing ribs and flanged them. Used my router with a peice of plywood screwed to it as my hole cutter with 1/4" holes and a bolt as my pivot point in the tooling holes.

First hole I cut the center hole to the larger hole dimensions so that rib was scrap..
After finishing I cut out a replacement rib blank and bent it over the forming blocks. I had my ghetto hole cutter set to the smallest hole size so cut it first...... however it was only supposed to have the 2 larger holes cut in it so reinforcement could be riveted to it on the fuel bay..

so in the end I have 1 extra rib(I still flanged it so it is a good completed rib) and one scrap rib.

Flanging with the dies was easy just using a rubber mallet. I was just careful to keep them square and hold pressure down on the male die once started to prevent it bouncing, I didnt just wail away at it with the mallet but more controlled hits mostly centered to start, then finished off around the parameter once down mostly formed.

On the zenith forum someone posted yesterday having issues with his ribs being warped after hand flanging(not using a die) so I payed close attention to mine to see the difference.

You can see it is stretched some but snaps back straight when the edge flanges are held at 90° so I think it is ok.

All in all, not bad for an evening after work

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Total time spent building: 37.5 hours
Total Cost: $8276
Airplane + consumables + project specific costs: $5340
Tools, etc.. I will keep for future projects: $2936

[Jeff]

Nice work Narfi!!! Jeff

[Netpackrat]

Those look nice. Yeah, there is a bit of a knack and some post flanging stretching needed when hand flanging. I have been an advocate of that method due to not needing to make one time use tooling, although if I were doing it today, I might go with the flange dies since I have a lathe to make them now.

[narfi]

I am pretty happy with the wooden die project, it was fun to make them and I think saved me time even already.
Last night in 3.5hrs with the mistake pieces I cut and flanged 48 holes. How long would it have taken me to flange them by hand?