CH 750 Cruzer Build Log

Discussion in 'Member Project Logs' started by Wayne, Dec 21, 2014.

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  1. Dec 21, 2014 #1

    Wayne

    Wayne

    Wayne

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    Hey folks,
    Well Dad and I have decided on a project, and work is underway! This thread will document a Zenith 750 Cruzer build. We completed the rudder at the Zenith Factory build session back in May 2014, and have just ordered and received the tail-kit. The Tail-Kit includes the horizontal stabilizer, elevator, trim surface, and electric trim servo.

    The Zenith Cruzer is match hole drilled, and many of the holes look to be final size so far. As such this airplane is more of an assembly project so has a much lower skill requirement than the plans built kits a lot of you are working on.

    About me: I grew up in the UK, moved to the Chicago, USA area in 1990 and am a newly minted Private Pilot. I have no prior aircraft building experience, but loads of model airplane building and recently completed a V8 conversion of a 1958 Triumph TR3. You can see it here on YouTube: https://www.youtube.com/watch?v=MYk4eFVzY9I

    I am fortunate to be the President of the local EAA Chapter so have access to some amazing local help, and of course everyone here on Homebuild Airplanes.

    Wayne
     
  2. Dec 21, 2014 #2

    Wayne

    Wayne

    Wayne

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    Location:
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    May 22nd & May 23rd, 2014
    8 Hours
    Built the Cruzer rudder at the Zenith factory during an assembly workshop with the exception of the rudder control horn, rudder tip rib, and plastic cap which still need to be finished.

    IMG_1672.jpg
     
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  3. Dec 21, 2014 #3

    Wayne

    Wayne

    Wayne

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    December 16th, 2014
    1 Hour, project total is 9 hours
    Cruzer tail-kit arrives and I unboxed it, laid out the parts, and inventoried. Everything in perfect condition, present and correct. Zenith did a very nice job of packing and shipping. The guy in the photo is my Dad (he's 83!)

    The Tailkit Arrives.jpg Tailkit1.jpg Tailkit2.jpg
     
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  4. Dec 21, 2014 #4

    Wayne

    Wayne

    Wayne

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    December 17th, 2014
    2 Hours, project total is 11 hours
    Following the instruction manual I deburred rivet holes on the 5 parts associated with the rear spar - the spar itself, caps, and doublers. All parts fit properly and are nicely made.
     

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    Last edited: Dec 21, 2014
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  5. Dec 21, 2014 #5

    Wayne

    Wayne

    Wayne

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    December 20th, 2014
    5 hours, project total is 16 hours
    Test assembled the rear spar, trimmed the rear spar support bracket to facilitate elevator travel, and deburred the front spar and it's doublers.

    IMG_1651.jpg Rear Spar Support Bracket.jpg IMG_1668.jpg
     
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  6. Dec 27, 2014 #6

    Wayne

    Wayne

    Wayne

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    December 26th, 2014
    1 Hour, project total is 17 hours
    De-burred rib rivet holes, and smoothed edges on the Scotchbrite wheel.

    Christmas was as fun and hectic as usual and I hope you enjoyed your holidays where ever you are.

    We are currently slowed down a bit because we are waiting for our Cortec anti-corrosion primer (Cortec Corporation | Products) to arrive from Zenith (I forgot to order it) and don't want to start riveting without it. This also gives our EAA technical counselors the chance to validate we are de-burring and edge smoothing correctly before we start chucking stuff together. De-burring and smoothing seem to be one of the key issues with this type of homebuilt due to cracks forming from improperly prepared edges and corners, and burrs around holes preventing the close contact between the parts that is needed for strength.

    Cortec rationale: We used this clear water based protectant at the Zenith Factory Rudder Workshop and really liked it because it can be applied quickly and easily by brush, cleans up with water, and creates little waste. Adding corrosion protection is a personal project choice - it seems to be hotly debated in some circles due to added cost in terms of time, money, and weight - with folks saying that the type of Aluminum we are using is very resistant to corrosion anyway. I totally understand the time cost, to a lesser extent the money cost, and my argument for the weight penalty is easy. Just check out the pictures above - you can easily see where I can capture the pounds back!! There are many alternates to Cortec - ranging from Zinc Chromate, to Duplicolor/Napa self etching primers to two part epoxies and more I'm sure.

    IMG_1697.jpg
     
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  7. Dec 28, 2014 #7

    Wayne

    Wayne

    Wayne

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    December 27th, 2014
    2 Hours, project total is 19 hours
    Dave O, one of our esteemed Technical Counselors was able to pop by and check our de-burring and edge smoothing. We got the thumbs up with the exception of a few edges that needed more work.

    Given that we are losing time while we wait for the Cortec to arrive, the decision was made to use Napa 7220 Self Etching primer to provide corrosion protection for the rear spar caps, doublers, and bracket. Accordingly the "contact" areas were prepped by roughing the surface with Scotchbrite pad and then cleaned with lacquer thinners. The primer was sprayed and left to dry. It was then an easy job to Cleco the parts back in place and rivet the bottom cap/doubler as shown in the picture. Nothing else was riveted because future steps such as adding the skins/ribs would have been prevented. The pneumatic gun worked perfectly to drive the A5 rivets in. Tomorrow I'll tackle the front spar!

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  8. Dec 29, 2014 #8

    Wayne

    Wayne

    Wayne

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    December 28th, 2014
    4.5 hours, project total is 23.5 hours
    Today was very busy and productive. I was able to get the front spar, front spar caps, attachment brackets, and attachment bracket doublers de-burred, smoothed, primed and assembled. I forgot to take in-process pictures of the spar cap work but you can see them riveted in place in the pictures below. Riveting the front spar attachment brackets and doublers benefited from the hand riveter as there was not much room - it was no biggy though.

    After getting the brackets on I test fit the front and rear spars with the 6 "non-tip" ribs - they needed to be installed a specific way but it was pretty easy to figure out - Zenith even labelled the front :) As I mentioned above - every hole has been final size thus far however this streak will end soon as the holes at the top and bottoms of the spars need to be upsized to accept an A5 rivet, the middle holes are A4. I think this will amount to me upsizing only 24 holes :)

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  9. Dec 30, 2014 #9

    Wayne

    Wayne

    Wayne

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    December 29th, 2014
    1 hour, project total is 24.5 hours
    Didn't take any pictures today - all I did was de-burr and smooth 3 of the 6 stabilizer ribs. I'll be sure to add some next time though. The Cortec arrived which is awesome because now I won't be stinking up the garage with self etching primer, and I also won't have to open the garage door and lose my heat just to get the fumes out! An unexpected bonus was that the product has a two year shelf life - I thought it would only last one year. I'll be sure to provide detailed information about usage etc. so anyone coming behind me can easily find the info.
     
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  10. Jan 10, 2015 #10

    Wayne

    Wayne

    Wayne

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    January 9th, 2015
    1 hour, project total is 25.5 hours
    Hey folks - well we are back from our family vacation over New Years, it was great and I hope yours was too. We tried something totally new and went to Puerto Rico, and it was wonderful - beautiful country, and lovely people. I even got a chance to rent a 152 and go flying. Here's an edited video: https://www.youtube.com/watch?v=niR7jzPA9Tc.

    So as you know it is brutally cold here in Illinois, USA (80F in Puerto Rico and -5F here!!!) but I figured I needed to press on with the project. I was fortunate the poor old electric heater was able to take the edge off the cold, from -5F to 40F. I still ran out of steam early though. I did have an epiphany, however, which was awesome - overcoming obstacles is one of the most important parts of succeeding at something, the journey is really the important part, so just going out to the garage and de-burring the remaining 3 stabilizer ribs (while not a great amount of progress) was an important part of the journey because I really didn't want to do it due to the cold. If I can keep this up Dad and I will have accomplished something fantastic, and every step of the way is a win, a triumph, over doing "nothing".

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  11. Jan 12, 2015 #11

    Wayne

    Wayne

    Wayne

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    Saturday January,10th, 2015
    1 hour, project total is 26.5 hours
    Today I prepped the ribs and spars with anti-corrosion protection by scuffing the overlap points with a purple scoth-brite pad, cleaning twice with lacquer thinner, and applying the water based product Cortec. Builders can get Cortec from the Zenith Aircraft company in 1 Quart containers which is very good because the manufacturer supplies it in 5 gallon pails, or 55 gallon drums - enough for a whole fleet of home-built planes! Shelf life for the Cortec was listed as 2 years and it can be applied in temps as low as 35 degrees and well north of 100 degrees. When I opened the can I was immediately reminded of that white rubber cement I used as a kid (I'm sure I'm dating myself!). It looks like the white sap you get out of Dandelions, and smells slightly of ammonia or something similar. As you can see from the picture it brushes (or sprays) on white, but then dries totally clear. I washed the brush off with Dish Soap and warm water and it cleaned right up. I had the garage up to about 50 degrees F by the time I painted it, went out for a couple of hours, and it was dry to the touch when I got back. All in all it's hard to imagine how much cleaner and easier corrosion protection could be.

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  12. Jan 12, 2015 #12

    Wayne

    Wayne

    Wayne

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    Sunday January 11th, 2015
    2 hours, project total is 28.5 hours
    With the Cortec fully dry, and an inspection of my deburring/edge smoothing from one of our technical advisers complete and approved, I riveted the ribs to the spars. I needed to enlarge the top and bottom rivet holes for the center 4 ribs because the spars use size 20 holes for A5 rivets, but the rib is pre-drilled for A4 rivets which are smaller. This meant I needed to drill a total of 16 holes, then deburr them.

    My riveting was not perfect - I had to remove three rivets because the joggled flanges did not get pulled down tight enough to the surface of the spar doubler. I removed the rivets by knocking the solid steel core through from from the rivet head backwards using a punch, drilled the head off using the same size drill as the rivet hole, then knocked the headless rivet through with the punch. On one of the rivets I had to grab the tail and twist it to loosen it for removal as it had expanded so tight in the hole. I re-installed the rivets and held the flanges tight against the doubler and they pulled up nicely. I need to pay more attention to thins like this moving forward.

    The next step is to deburr the stabilizer skin. I got one side (of 4) done very easily using the epic deburring tool my Dad assembled from a very high quality deburring bit and a slow speed low torque screw driver. He's an amazing guy - just hopped on amazon.com and took care of business - not every 83 year old can do that!

    Progress is good which is important since the wing kit will be arriving next month! What a great way to spend the winter!

    Not Tight.jpg IMG_1853.jpg IMG_1854.jpg IMG_1856.jpg IMG_1857.jpg
     
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  13. Jan 13, 2015 #13

    Wayne

    Wayne

    Wayne

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    Monday January 12th, 2015
    2 hours, project total is 30.5 hours
    Tonight I finished deburring and smoothing the edges of the elevator skin. I remembered to round the corners so am building some procedural memory :) I also touched up the edges of the spars because they were not as "broken" as they could be. I didn't take any pictures because the skin looks exactly the same as it did last night - at least as far and my phone camera is concerned :)
     
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  14. Jan 14, 2015 #14

    Wayne

    Wayne

    Wayne

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    Tuesday, January 13th, 2015
    2 hours, project total is 32.5 hours
    Dad popped by tonight to help prep the stabilizer skin and frame for corrosion protection. We used Scoth-Brite pads to scuff the surfaces that touch, de-greased with lacquer thinner, and then applied a coat of Cortec. By the time we were done straightening up the garage the Cortec had gone clear, and was dry but sticky to the touch. I have 50 degrees out there right now - the little 220 Volt heater is doing well now that the garage ceiling is insulted.

    Dad picked up a set of small files today that have already proven their worth - the stabilizer skin has channels precisely cut out for the front attach brackets, and these need to be edge smoothed and the corners broken. The small files made this easy.

    Tomorrow or Thursday we skin the elevator!

    IMG_1859.jpg IMG_1860.jpg
     
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  15. Jan 15, 2015 #15

    Wayne

    Wayne

    Wayne

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    Wednesday, January 14th, 2015
    1.5 hours, project total is 34 hours
    I really didn't want to work on the plane tonight - it has been a long and annoying day and I would have been happy being lazy. It turns out, though, that I got a call from Arnie - he wants to come over and help work on the build so I'm going to have him and Dad help me accomplish a major milestone tomorrow by setting the first rivets in the skin!

    Accordingly I had to get the stabilizer ready for them to get all the glory. Still - having them hang out with me increases my street credibility quite a bit so it's worth it.

    I screwed a 1 x 2 to the bench so that the front spar is up a bit, this has the effect of raising the curved ribs off the table and let's the spar sit flat. Next I made some blocks from the leftover 1 x 2 and used them to lock the rear spar in place so it didn't move around. Placing a level on the front and back spars indicated that they were very close to being in the same plane - close enough that I don't think there was much I could do to get them closer. Don't be misled by the picture - the bubble was right on the line from one end to the other on both spars. The slope is either due to the garage floor or the trestles being unlevel but that is not important. What matters is that there is no twist in the panel.

    I had my daughter help me lower the skin onto the frame, and we located it by passing the front attach bracket through the precut holes in the skin. After this I simply started clecoing from the center out making sure I had everything lined up. All of the holes are pre-drilled for A4 rivets and after some tweaking to get the frame square it settled in perfectly. Some of the Cortec we painted last night leaked through the rivet holes during painting and I freaked out because I could not get it off by scraping or buffing with Scotch-brite. Lucky me though - it turns out that cured Cortec can be easily removed with Lacquer thinner! I wonder what that stuff won't remove.....

    We are all set for the rivet-a-thon tomorrow. I hope they at least bring beer.

    IMG_1861.jpg IMG_1864.jpg IMG_1862.jpg IMG_1863.jpg IMG_1867.jpg IMG_1868.jpg
     
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  16. Jan 16, 2015 #16

    Wayne

    Wayne

    Wayne

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    Thursday, January 15th, 2015
    2 Hours, project total is 36 hours
    As promised the ancient ones turned up right on time - 6 O'Clock sharp - and started tearing into the project. It seemed like they went into some kind of mind meld which allowed them to move intelligently, quickly, and for brief moments were capable of speech.

    Between them they were able to rivet up the bottom skin on the stabilizer, flipped it over still smoking from over-worked rivets, and stared at me - waiting for the next task. When I explained they had accomplished pretty much everything we needed to get done they started growling and muttering about WW2 - this is not how we were we able to produce a plane every 30 minutes back then ..... After they stomped off in disgust I realized that I might have hit upon something revolutionary - who needs robots or offshore for cheap labor - just mind meld two old guys and get out of the way!!! What's really scary is that today is National Hat day,and I'll be da^&ed if they both were representing the "hat" cause, whatever it might be...

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  17. Jan 17, 2015 #17

    Wayne

    Wayne

    Wayne

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    Friday, January 16th, 2015
    3 hours, project total is 39 hours
    Tonight I got everything sorted out for the stabilizer tips ribs. Each tip rib is supported by 2 x L angle stock braces, so 4 in total. Each was cut to 75 mm long from the provided 4 foot section (yes I'm mixing units) and shaped per the plans. Holes were drilled, deburred, and the parts painted with Cortec. Once the Cortec was dry I riveted them in.

    With the tip ribs in place the next step is to fold the top skin over and Cleco it in place. This was very easy using the long 1 x 2 to spread pressure across the whole length. I did notice that the sheet was running long on the trailing edge and was occluding the match holes drilled there. I have skinny Cleco's so I lined up the rear in conjunction with making sure the ribs and front spar were also lined up. The parts as supplied by Zenith are amazingly accurate but it is possible to have some float because Cleco's don't guarantee a 100% centered lock down and over distance small errors can creep in. I've started to check "what I'm doing now" with "what are the consequences" and am getting better.


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  18. Jan 19, 2015 #18

    Wayne

    Wayne

    Wayne

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    Saturday, January 18th, 2015
    6 hours, project total is 45 hours
    Today was a big day because we sealed up the stabilizer. On the surface it might seem that not much needs to get done, but we had to locate the elevator hinge very accurately, drill and deburr it and then go back and deburr the skin, spar, and doublers because drilling the hinge caused burrs on all of those pieces as well. We took a slower route to deburr the skin and spar by removing all of the cleco's holding the top skin down so that we could get in with our normal deburring tools. One suggested method is to use a file in-between the skin and spar to remove the burrs and while this is surely effective I didn't like the idea of scraping off the corrosion protection indiscriminately and lifting the skin up prevented that and also let us vacuum the inside to remove scraps. This is the OCD kicking in I think :)

    The hinge works beautifully with no binding so all the time was well spent. Dad and I then proceeded to rivet everything back together. The whole unit is amazingly rigid now and we are proud if it!




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  19. Jan 19, 2015 #19

    Wayne

    Wayne

    Wayne

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    Sunday, January 19th, 2015
    5 hours, project total is 50 hours
    We all know that no stabilizer is complete until it is dressed up with cool blow molded tip caps. When trimming the caps from the stock material I noticed that the rear of the piece is untidy, and one of mine has a crack developing as you can see from the picture. From what I can tell the molding process has to accumulate a lot of material at the thinner back end and I'm sure the results are not what they hoped for. I think, however, we will be fine working with what we have. I went to the hardware store and purchased some Loctite Plastic welding epoxy with the idea of using it to glue the crack shut. I have a test piece running right now and it looks very promising - the product acts like the plastic glue we used to use on our plastic models way back - it melts the plastic back together, then seems to have a bulk to it like a normal expoy that provides backing strength. If my test pieces look good tomorrow when cured that's what I'll do to fix the crack rather than returning it to Zenith.

    After a number of attempts I came up with a good way to clean up the parts and to create nice straight edges - by clamping my metal yardstick to the part and using as a guide for my coarse file. Worked really well, and also worked really well as a guide for my razor knife.

    I had a HECK of a time making sure the extended tip rib was 90 degrees to the spar so the we have a perfect rectangle for the elevator to fit into. I finally worked it out using a regular square and hope I'm at least close. We will see :

    In any case - holes have been drilled and cleco's set. I got tired so figured I'd check the work tomorrow for fitment.

    We are getting real close to building the elevator, trim tab, and servo. Hope we get done before the wings come! This has been the best winter ever so far - who has fun in the garage at this time of year?

    Oh - BREAKING NEWS - I got checked out on the Remos GX today and got signed off so have another great plane I can rent and fly. I took a short movie that I'll edit back in here later. Snippets from my checkout https://www.youtube.com/watch?v=U-N0OijkbaU



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    Last edited: Jan 19, 2015
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  20. Jan 22, 2015 #20

    Wayne

    Wayne

    Wayne

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    Wednesday, January 21st, 2015
    2 hours, project total is 52 hours
    Hey all - I've been out of town on business (in Green Bay, WI after the loss to Seattle - not great timing) so I have been lagging
    :) Tonight I worked on the crack in the left tip - I opened it up with my knife so I could get some of the plastic epoxy glue in, then drilled a tiny stop hole (it will be filled with epoxy so maybe that was a waste of time) and filled the crack to the top, and inside on the back allowed a little build up. My tests proved that the glue is highly effective at melting and then hardening the plastic so I'm extremely confidant in the bond - especially as it is in this non-structural area. I've learned a little from working on the left tip so the right one went much faster and is nicely trimmed. All of the holes are drilled and it seems that everything is lined up OK. I got tired so came in - deburring can wait until tomorrow. The good news is that once the tips are complete I move on to the elevator! I have copied the image on my Avatar and am using as the background of my work laptop. My next plan is to see if the wife will let me paper the kitchen with Zenith Cruzer wall paper. I'll let you all know how that goes :)

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