# Narfi's Scratch Built Zenith 750 Super Duty

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#### narfi

##### Well-Known Member
Log Member
If you are scratchbuilding, have you researched the home-built sheet metal brakes that have been developed for stuff just like this? There are even home-brew brakes that mount to the edge of your bench.
Yes, but with access to my neighbors 12' brake and the 4ft box break we have at work, I figured I don't need another 'build' project to distract me

#### narfi

##### Well-Known Member
Log Member
I like that kid...
Me too, he is a great kid. I blame his mother, but I try to show him stuff that will help him out later in life as well.
His project this weekend was getting an old shattered plastic sled usable since we wont let him use his new one for towing when the roads are icy and covered with loose gravel(or he will destroy it pretty quick) So he was drilling holes and stitching the old shattered one together with zipties so him and his friends could tow each other around behind the Honda.

#### narfi

##### Well-Known Member
Log Member
~8 hours over the last few days.
Built the rest of the rudder parts.
Tip rib, rear ribs and forward rib.
Going slow because they don't have the scratch built plans yet. Roger has been taking pictures of parts with the tape measure beside them. I'm sure he is getting tired of me calling

Last night I attached the ribs to the spar and everything looked good except the forward rib seemed too wide for where it attaches between rear ribs 2 and 3. It fit perfectly against rib 2 but after talking to Roger today my parts are the right demensions and it for sure goes a few inches further (narrower) up the spar. I will play with it tonight and probably just need to bend the flanges down a bit tighter.(I hope)

Then I will take it apart and put the spar doublers in place and the hinge brackets.
All of this is being done with a #40 drill bit for pilot holes and fitting. Once it's all cleaned up and fitted I am hoping Landon will want to do final drilling for size.

The skin is going to be interesting as there are no pre punched holes for aligning the ribs. But I think once I actually fit it together it won't be too big a deal to get lined up. I have the angles the ribs are supposed to sit from the spar.

Total time spent building: 77 hours
Total Cost: $8803 Airplane + consumables + project specific costs:$5867
Tools, etc.. I will keep for future projects: $2936 #### Attachments • 70.7 KB Views: 7 • 72.2 KB Views: 7 • 69.5 KB Views: 7 • 62 KB Views: 6 • 67.9 KB Views: 6 #### narfi ##### Well-Known Member Log Member Unrelated but kind of fun. A few weeks ago we were at the hanger on the weekend and Landon had fun building a "perfectly useless object" He cleaned up a couple of scrap circles of aluminum someone had taken out of a hole saw and bent them on the brake and drilled and riveted them together. His first time driving rivets and only had to drill and replace one. (I drilled it out, but he drove them all himself) Then he etched and scratched it and painted blue with some cheap rattle can we found in the cabinet. #### Attachments • 125 KB Views: 16 • 25.6 KB Views: 15 • 28.5 KB Views: 12 • 32.6 KB Views: 15 • 38.6 KB Views: 15 • 55.1 KB Views: 18 • 68.8 KB Views: 17 #### Victor Bravo ##### Well-Known Member HBA Supporter That ain't useless at all ! It's actually a key structural component , called the Youth Self-Confidence Consolidator, which is a known cause of a condition known as Addictive Achievement Syndrome, which is shown to lead to an acute case of Dynamic Employment Acceleration ! In several cases, Financial Obesity has been reported. #### narfi ##### Well-Known Member Log Member ~6hrs Bent the trailing edge skin. Drew out the angles of all the ribs from the spar on a sheet of plywood with centerlines extending beyond the edges. Layed out the skin on the drawing and drilled the trailing edge pilot hole for each rib. Drew centerlines on all the ribs and inserted the skeleton into the skin. With the spar and trailing edge blocked for jigging. Clamped the skin to the spar where I had marked it belonged and lined up the ribs till I could see the center lines through the pilot holes, drilled and clecoed. Drilled a pilot hole in line with the rib centerlines at each intersection on the spar and then used a rivet spacer fan(not sure proper name) drilled along each rib all the pilot holes pitch 40 or less. Flipped it, rejigged it, and did the same on the other side. Using the river spacer drilled all the holes along the spar spaced evenly between all the ribs on both sides. Made the lower splice plates and drilled and clecoed them in place. I bent my rear skin square with a full width 48" sheet and it ended up a little shorter than the plans, I'm guessing they bend at an angle to get a little longer or something. No big issue, my splice plates just look a little different. Removed the clecos where the lower forward fairing attaches and slid it between the skins and spar. Marked a line on each side so I would know how far to slide it in, then drilled through the pre existing akin holes and clecoed it in place. Next up I need to form the leading edge and fit it. Then will drill all the holes to final size and clean it all up for priming and final assembly. Total time spent building: 83 hours Total Cost:$8803
Airplane + consumables + project specific costs: $5867 Tools, etc.. I will keep for future projects:$2936

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#### narfi

##### Well-Known Member
Log Member
Well we moved back up to the top floor this weekend.
Landon's room is done and everything else nearly done, still waiting on the black iron for the rails on the stairs and a few touch up spots here and there but close enough to move back in. Hope to get back to working on the airplane in a few days, still need to do alot of sorting and putting stuff away.

I am pretty happy with the way the bed turned out, spent half a day putting all the hardware on, but it really makes it imo.

#### narfi

##### Well-Known Member
Log Member
~5hrs
Landon helped me cut a piece of aluminum for the rudder leading edge and vacume form the radius before the sounds of kids in the neighborhood distracted him.

I got it fitted in place sandwiched between the spar and rear skin to drill all the pilot holes to the spar.
Got the lower rib aligned and drilled. Dinged the leading edge a little with the squared off front of the rib sliding it back and forth, but not bad enough to need to redo it all. Lesson learned though, I should have left the skin looser right there.
I need to call Roger and find out the shape and dimensions to trim the lower section of the skin, the drawings show it curved up, but looking at some recent assembly videos online it looks straight.... Is it trimmed to fit after installing on the tail? Or is that supposed to be done now?

Next up will be shaping the rudder horn, I already have it rough cut and bent, just need to grind down the final shape and fit it to the lower rib.

This weekend I hope to get Landons help redrilling all the holes to final size and cleaning up for priming. Will see how timing goes around the house

Been snowing, and as we all know, that means it's warm enough to comfortably work out in the tent for longer periods again

Total time spent building: 88 hours
Total Cost: $8803 Airplane + consumables + project specific costs:$5867
Tools, etc.. I will keep for future projects: $2936 #### narfi ##### Well-Known Member Log Member Just talked to Roger and he recommended not trimming the lower leading edge skin until assembly so that it will be cut to fit at that time. He will be getting me dimensions for the Stabilizer and Elevator spars next. I already have the ribs built up so hopefully they will start coming together in the next week or so as well. #### narfi ##### Well-Known Member Log Member ~1.5hrs Landon started drilling out the holes to final size. I had it all drilled out with a #40 and alternating holes with silver clecos. He drilled up to a #30 and put in the copper clecos then removed the silver and drilled them out as well. He did most of one side, I'll probably finish up tonight. While he was doing that I finished shaping the control horn and fitted it. Total time spent building: 89.5 hours Total Cost:$8803
Airplane + consumables + project specific costs: $5867 Tools, etc.. I will keep for future projects:$2936

#### Victor Bravo

##### Well-Known Member
HBA Supporter
The wonderful part is that this young man has no idea that he's actually building the airplane he's going to do his first solo in...

#### Richard6

##### Well-Known Member
Hearing and eye protection is a good thing.

You and Landon's work looks good.

#### narfi

##### Well-Known Member
Log Member
The wonderful part is that this young man has no idea that he's actually building the airplane he's going to do his first solo in...
oh, he knows

Hearing and eye protection is a good thing.

You and Landon's work looks good.
The drill is pretty quiet and I always wear glasses, so I didn't even think of it. That is a good reminder, thanks!

#### narfi

##### Well-Known Member
Log Member
~8hrs
Did the final trim along spar rivet line of the leading edge skin.

Drilled out the hinge holes on the brackets. Debuted all edges and holes.

Hauled everything over to the hanger I work at and prepped for priming and primed.

Put the extra mixed primer in the freezer to keep it from kicking.

Went back the next day and wrapped everything in towels and brought home.

We riveted the skeleton together and then the skins and control horn. We brushed primer on both sides of every joint and seam before assembly and riveted together "wet."

A few weeks ago I had Landon working on a practice sheetmetal project with solid driven rivets. His comment yesterday was "this is a LOT easier." ...... I agree with him, pulled rivets feels like a cheat code for assembly. No stress and much quicker.

Once done brought the finished rudder inside over night for the primer in the seams to cure. Was fun waking up this morning to a nicely finished part to greet me.

Total time spent building: 97.5 hours
Total Cost: $8803 Airplane + consumables + project specific costs:$5867
Tools, etc.. I will keep for future projects: $2936 #### Victor Bravo ##### Well-Known Member HBA Supporter That's a beautiful rudder! #### narfi ##### Well-Known Member Log Member Well some bad news from Roger yesterday. He had told me to build the STOL horizontal and elevator ribs last fall, turns out they need to be the 801 ribs, so I am waiting on him to get me dimensions on making formers for them now :/ As fast and easy as the rudder went together, we are eager to start making some more progress.... #### narfi ##### Well-Known Member Log Member ~4.5hrs Cut the strips, debuted the edges and bent the spars and doublers for the horizontal and elevator last night. It's an old brake at a neighbors I am using and it used the full 10ft of it, bending sharper at one end and bowing a little in the middle creaking and groaning the whole time on the .040. I got the angles closeish and will finish them with the hand seamer like I did with the rudder spar. It's close and the bends are straight and where I want them so shouldn't be to hard to finish them off. Once I have them bent to my satisfaction I will tweak the rib dimensions Roger gave me to match perfectly to the spars and build the new formers and cutting blocks for them. Total time spent building: 102 hours Total Cost:$8803
Airplane + consumables + project specific costs: $5867 Tools, etc.. I will keep for future projects:$2936

#### narfi

##### Well-Known Member
Log Member
~9hrs

Spent an hour Friday working the angles on the spars and doublers.
About 8 hours sunday afternoon building forming and cutting blocks for the horizontal ribs, cutting them out and forming them.
The first time around when I thought I was building the 750stol ribs I built 3 form blocks, one for the leading edge, one for the middle and one for the full ribs, this time I just made the one full sized former and used my hand seamer to bend the hidden flange on the nose and middle ribs. I still made 3 sets of cutting templates to run the router around for cutting the aluminum.
Of course after forming the ribs I had to dummy them up to the spars to get a peak at how they will look

Roger is gone to Sun n Fun, so I won't be able to get dimensions on the center hinge assembly parts or rib spacing or attach brackets until he is back next week. Spacing seems most critical on the center two ribs as the forward attach brackets match up with them and from what I can tell need to be spaced appropriately to match the fuselage width and fuselage side of the attach brackets for bolting on. (and I obviously haven't built the fuselage yet....)

I have seen some people build increase the size of the outer hinge bracket to form a strake on the outer ribs of the horizontal. Any thoughts on if I should do that here? I am strongly leaning towards yes. I like the looks of it. It probably does help some. I intend to build floats for it at some time, and although I have not read anything yet about float characteristics for it, nearly all certified aircraft I have put floats on require more stability back at the tail. For example Cessna has a larger rudder and a dorsal fin bolted on under the tail and beavers have a plate bolted on the outer edge of the horizontal stabilizers looking almost exactly like larger versions of what I have seen done on zeniths. What do you guys think?

Also ordered the elevator trim system from Aircraft Spruce, It includes the Servo, clevis/pushrod kit, as well as switches and indicators. $372 Total time spent building: 111 hours Total Cost:$9175
Airplane + consumables + project specific costs: $6239 Tools, etc.. I will keep for future projects:$2936

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#### narfi

##### Well-Known Member
Log Member
Twiddling my thumbs waiting for Roger to get back from Sun n Fun.
Ordered some 2.5"x2.5" square steel tube for straight jigging, should be better than using old 2x4 lumber..... $336 in the tools I will keep column Ordered some piano hinge from Aircraft Spruce$30

Total time spent building: 111 hours
Total Cost: $9541 Airplane + consumables + project specific costs:$6269
Tools, etc.. I will keep for future projects: \$3272