I found the family clecos while looking for something else in the garage.
Author: Dean Betz
It’s time to pull some rivets. And make a few mistakes.
I had a busy week on the rudder. The skeleton went together quickly last week, with all mating surfaces coated with an anti-corrosion film (Cortec) and the bits reassembled for riveting.
On Wednesday riveting began, with some missteps. I got carried away and put a half-dozen rivets in the skeleton where they won’t supposed to go yet, so got some experience in drilling out blind rivets without enlarging the hole. That turned out to be easier than I had expected. Everything aligned as expected, and in a couple hours every rivet was in its place on the skeleton and I was ready to put on the skin.
Thursday was a day of great progress. The skin went on with little difficulty — it’s a pleasure to work on an airplane kit where the vast majority of holes are drilled to size and ready for assembly. It didn’t take long to get the skin in place and cleco’d up.
One of the pleasures of this project is where I get to work on it. I’m taking classes in the aerospace program at Renton Technical College, this quarter learning precision machining and related skills like inspection. As part of that, I have access to an incredibly well-equipped aviation workshop, which I’ll detail a bit more in another post. I also have the benefit of working under the instruction of Vincent Phillips McLellan, who founded and runs the aerospace program. He’s given invaluable advice in how to attach the skin to keep it as flat and straight as possible, how to correctly use the tools, and many other skills. A lot of the reason I have confidence in what I’m doing (more on that later) is being able to draw on these resources.
On Friday came the fun part, pulling rivets on the skin. In short time I had the end cap assembled and cleco’d in, and the rudder horn in place. At Vince’s recommendation I’ve started at the trailing edge, in the middle of the rudder, and worked my way out and up. Shop lighting makes the skin exaggerates the waves between the ribs — outdoors and in regular lighting it’s straight. I’m about a third of the way through riveting, but will need to do a little remediation first.
Now, for some mistakes. Putting on the top cap assembly I inadvertently drilled a hole straight through both sides of the skin. After cursing, I followed the advice of the Zenith assembly manual — if you put a hole in the wrong place, just put in a rivet and don’t sweat it. In this case, the extra rivet is at the top a tall rudder, in a place where it will be inconspicuous. And lesson learned.
A bigger concern to me is getting the rivets in true. After wrapping up for the day I did a pretty thorough inspection of the rivets I’ve placed so far on the skin. There are a lot that aren’t sitting as flat as I’d like. The manual says it’s not seated correctly if you can put a fingernail under the rivet, and probably a quarter of what I’ve pulled so far fails the fingernail test.
I’ll be spending the weekend reviewing my Homebuilder Help videos and assembly manual to figure out what I’m doing wrong, and marking the rivets that need a do-over. On Monday I’ll get some help from Vince and starting drilling out some rivets.
Now I’m started to understand why Zenith includes the rudder in the tail kit, whether or not you’ve already built the rudder starter kit. Depending on how this piece turns out, it’s possible I’ll build a second rudder to get my work as high-quality as possible. Hey, it’s a learning process, right?
I had the last lesson before the checkride today, and the instructor and I agreed that I’m not there yet. It’s not that the maneuvers elude me — flying the plane is not an issue — it’s assembling the specific maneuvers within reasonably tight tolerances with a consistency that remains a bit of a pickle.
I’ve scheduled three lessons before the next opportunity for the checkride, and will be working like mad to align my abilities to match the checklist. I never had confidence that I was prepared for Tuesday’s test, but kept working toward that as a goal, so I’m not disappointed. Lindy willing these two (no, three) tactics will help me get there by the end of the month:
1) Fully utilizing the checklist
2) Talking through each step in the checklist
3) Using the checklist
Perhaps there will be more promising news this week on the assembling-the-rudder front.
… just in case you have missed it in the past …
Let the drilling begin
I finally broke the seal today and started assembling the rudder from the pre-drilled kit.
It was a slow start, as I needed to get up to speed with the Renton Technical College instructor whose shop I have the pleasure of using as I toy with the idea of building a plane. As you’d expect from a shop that prepares Boeing assemblers, it has all of the tools I’ll need — pneumatic drills and rivet pullers; air chucks at every workstation; all of the right drill bits, tool chests full of files, fussy little clamps, deburring tools, machinist’s rules, well-organized clecos, cleco pliers, and everything else you might need to assemble an aluminum airplane. For a sloppy-workbench guy like me it’s a dream!
I’m starting with the skeleton of the rudder. In the course of an hour I got a groove on assembling the spar, first by cleaning off labels and markings off of the pieces, which all have been cut, bent and mostly drilled at the factory.
So far about two-thirds of the work is done to clean, deburr and drill the holes needed to attach the doublers to the spar. It’s super-easy because the spar already has the holes, it’s just a matter of putting in the doubler holes and enlarging holes in the assembled pieces to the final size. Honestly, as a kid I made more complicated plastic models.
I won’t be back on the project until Wednesday. Next week’s goal is to see if I can complete initial assembly of the rudder skeleton in preparation for adding corrosion protection and starting to pull rivets. I’m guessing that dry-assembly work will take no more than several hours.
A friend on the Facebook Pages version of this blog loved the STOL video I posted earlier. Here’s another that shows the incredible short-takeoff performance of these planes.
Not to confuse matters, the version of the CH 750 family that interests me is the cross-country type. But some builders, including Jonathan Fay, have modified their Cruzers as excellent back-country planes that have great short-takeoff performance, as well. Without much sacrifice of a higher cruising speed.
They’re more than just holes in metal
I present to you my initial work as a student of precision machining at Renton Technical College, in Renton, Wash. These are blocks of carbon steel and aluminum drilled to tolerances of no more than 30 thou. (That’s 0.030 inches.)
Eventually, this course leads to a program in Aerospace & Industrial Production Technologies — it’s a pipeline to Boeing, which of course builds 737s at a plant about two miles away from the college. It also gives me access to resources that will be useful as I build a Cruzer rudder and toy with the idea of building an airplane.
Attention Oshkosh family
Wouldn’t it look great pulling into Camp Scholler in this bad boy?
“Andromeda is registered with the state of California, albeit as a 1979 Pace Arrow motorhome. A rescued 1957 Convair 240 airplane became 1980’s motorhome with full amenities, and even a hot tub!”
Convair 240 Airplane-RV Conversion with International Diesel Engine… (craigslist.org)
I will not get nervous about my check ride. I will not get nervous about my check ride. I will not get nervous about my check ride.
It’s scheduled for May 11 with a brand-new designated pilot examiner. If I don’t screw it up, I’ll then be an Official Licensed Pilot.
There’s an hour-long oral examination on everything I’ve learned as a student pilot, then an hour or so of demonstrating takeoffs, a series of flight maneuvers, and landings. The flying part should go something like this:
What is a Zenith 750 Cruzer?
It’s an all-metal, two-seat aircraft that meets the requirements of the sport pilot license. The Cruzer is the cross-country member of the CH 750 family, which includes a STOL “off-airport” plane and a stretch “super duty” version.
|Stall Speed||34 knots|
|Never Exceed Speed||126 knots|
|Rate of Climb||1200 fpm|
|Range||450 nautical miles|
|Empty Weight||780 lbs|
|Gross Weight (LSA)||1320 lbs|
|Useful Load (LSA)||540 lbs|
|Design Gross Weight||1440 lbs|
|Design Useful Load||660 lbs|
|Load Factor||+6/-3 g|
|Take-off Roll||350 ft|
|Landing Roll||350 ft|
The moment you’ve all been waiting for: The unboxing
The rudder kit was nicely packed, and the inventory was complete.
- Rudder horn
- Top cap
And best of all, 300 rivets to pull!
The next step will be studying the very detailed manual over the weekend and making a list of a few new tools I’ll need.