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Thread: Project 5 build thread

  1. #241
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    Default Re: Project 5 build thread

    I used the wing fold lock brackets to determine how far back the wings need to fold. I found the the wing lead edge was even the H-Stab ends.

    The Model 5 build manual does not list a step to fold the wings and check for clearance between the #1 rib and the rear cary through spar. I discovered it the hard way and had to grind on the #1 rib on the left wing after covering. Not ideal and wished I would have caught it pre-covering.

    Also if have a pitot mast, check to make sure it clears the top of the H-Stab when the folds are folded. I mounted mine where the manual says and it contacted the top of the H-Stab when the wing was folded. I ended up cutting 1" off the mast. Some have mounted the Pitot on the inside of the lift strut which would eliminate this issue.


    IMG_4122.jpg

  2. #242
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    Default Re: Project 5 build thread

    Jim and Jerry,
    Thank you. I do own the travel braces used during the wing fold procedure and I know where they're at. I guess it's time to figure out how to use them.
    Kitfox 5 (under construction)
    Commercial SE/ME, CFII

  3. #243
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    Default Re: Project 5 build thread

    As usual, any video I create is a bit behind the times. My trailing edge pieces for ribs 3-10 are done. Hoping to prep my fuel tanks tonight.

    Kitfox 5 (under construction)
    Commercial SE/ME, CFII

  4. #244
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    Default Re: Project 5 build thread

    My Verner Scarlett 7U is at Brahn Sport (one of three US importers for Verner) in New Mexico. It arrived in great shape.
    31156.jpg
    For those not familiar with radials, it is face down with the prop hub near the floor. Those are intake runners on this side and the carb is mounted directly behind the crankshaft centerline, what looks like "on top" in this picture. That carb is coming off and will be replaced by a throttle body fuel injection system. More on that later.
    31152.jpg
    No magnetos on this engine. Every spark plug gets its own coil, similar to a half way modern car. Those are the coils in the foreground. To the right side of the image is the oil tank. Now the oil tank on a "normal" radial like the R985, R1340 etc is mounted up high on the firewall behind the engine. Following Civil Engineering rule #1 (s*** always goes down hill), it can lead to hydrostatic lock. The R985 and friends have a scavenge pump which pumps oil back up hill to the tank.

    With the Verner, the oil tank sits below the bottom cylinders which is a distinct advantage for avoiding hydrostatic lock (the s*** is already at the bottom of the hill). There are three oil lines which drain back to the tank. One from the crankcase, and two are cylinder head drains. The main oil pump is sufficient to suck oil from the tank and push it through the engine.

    Regardless of where the oil tank sits, you still pull the prop through several blades to assure everything is free.

    With the R985 and R1340 I was taught to always park the plane with the prop set to TDC on the #1 cylinder. This leaves one exhaust and one intake valve open on the bottom cylinders 5&6 (talking 9 cylinder engine here). Any oil which does leak downhill and pool in the cylinders will drain into the exhaust manifold on one cylinder and the intake on the other.

    Small amounts of oil in the exhaust manifold poses no risk and just creates more smokey theatrics on engine start.

    That intake full of oil is still a big risk. If you pull the prop through there won't be enough suction to draw that oil into the cylinder and highlight the problem. It will wait until the moment the engine first fires up and then suck it in. Result is a bent connecting rod (or worse).

    Scarlett 7U.jpg
    Before I continue I will level set radial design. All single row engines I've been around follow this format: Cylinder #1 is straight up at the top. Then the order goes counter clockwise when viewed from the front with #2 at the 10 O'clock, 3 at 8:30-ish and so forth. Firing order is always odd then even, so 1, 3, 5, 7, 2, 4, 6 in this case. The cam (it's not really a shaft, it's a big plate with rounded corners) serves both intake and exhaust valves and you can probably guess where it's located.

    Back to the intake issue:
    The Verner comes with a small fitting on the intake runner of the bottom cylinder #5, and it is visible in the picture above. You open that briefly during preflight to see if anything drains out. With the R985 and R1340 we generally see a very small hole drilled into the low point of that intake runner. In theory it will weep out any oil which is pooling in the intake while it is parked, and is small enough not to impact the fuel/air on that cylinder.

    Me, I trust that stuff as much as I trust aircraft heaters, parking brakes and gas gauges - which is to say : Not at all.

    So I pull blades even if I just stop for gas. In a couple hundred hours of driving a radial I have never had cylinder full of oil, but I have experienced occasions when the compression on some cylinders seemed higher than normal. That's a sure sign of some extra oil so I just keep gently pulling blades until all the cylinders feel the same. In fact the only time I've had a radial even miss a beat was in the BT-13 on a cross country and my girlfriend accidentally pulled the power back while trying to put on warm clothes. But that's a story for another time.

    Back to the picture above you can see a circular section of braided line at the front of the engine. It squirts oil into the valve covers of cylinders 2, 1 and 7. That oil drains back down to the crankcase via the push rod tubes. The two drain lines I referred to earlier come from the two red caps you see on those bottom valve covers. Oil goes to cylinders 3 and 4 via the push rod tubes and drains down the braided line to a line which replaces the red cap and carries the oil to the oil tank. Cylinders 5 and 6 have the same thing going on their side.

    By the way, on an R985 or R1340 that ring on the front isn't oil. It's a manifold for the front spark plug wires, visible in this pic of the T-6 we had.
    IMG_20190608_083206-01.jpg
    I hope this hasn't been too boring. Lots more to come.
    Kitfox 5 (under construction)
    Commercial SE/ME, CFII

  5. #245
    Senior Member jrevens's Avatar
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    Default Re: Project 5 build thread

    That's very cool, Alex. Can't wait to see it in person someday!
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  6. #246

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    Default Re: Project 5 build thread

    How Exciting Alex!!! Your knowledge is very helpful for someone like myself that isn't, so thank you!!!!!!

  7. #247
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    Default Re: Project 5 build thread

    Armed with Jerrytex's rib relief scenario above I carefully relieved the inboard edge of my #1 cap strip to allow the left wing to fold completely. I made the same relief in the right rib so it would look intentional. I also visited my airport neighbor Nate to look over his 912iS installation and that always gives me another chance to look at what someone else did on their Kitfox. Nate had the exact same condition on his left wing and made a relief also. I had been concerned that the relief would look like a mistake every time I looked at the plane but it turns out the aluminum fairing which gets installed at the wing root covers it up anyway.

    Last Thursday I spent two afternoons preparing the fuel tanks. On the scale of enjoyment it ranks right up there with prepping for a colonoscopy. One afternoon was spent cleaning off the sticky foam used as packing protection, and sealing up the tanks with strapping tape so I could huff a bit of air inside and leak test the tanks with soapy water. That test went great. Knowing people have had problems in the past with tape coming off the various tank ports I spent the time looking for the strapping tape called for in the manual. I cleaned the area around each hole carefully with acetone, let it dry and then made double layer patches of strapping tape.
    PXL_20210701_024415143(1).jpg
    I rubbed the tape hard before putting on the second layer, larger than the piece under it, and rubbed it for good luck too. These pieces held up great for the leak test. For the acetone flush though, I learned what everyone else knows which is that acetone is kryptonite for tape. It's as if the tape is spring loaded once it gets soaked, which takes only seconds.

    Pondering a solution I remembered that my small parts drawers contained various sizes of tapered rubber plugs. They're squishy enough that you can twist them and screw them into the threaded holes. It worked fantastic! For the fuel filler holes I grabbed one of the gas caps (I have extras...) which I determined were either made wrong or for a different type of tank because the vent tube points at about 10 O'clock when viewed from above. With the defective gas cap in place I used one of the smaller tapered rubber plugs to close up the vent.

    PXL_20210702_011717766.jpg

    It worked so well that you have to be careful when removing the first plug after sloshing with acetone. The built up pressure vents like a surfacing dolphin when released. This business card was in the drawer with the plugs. I looked them up to make sure they actually supplied those plugs and that the company survived 2020. Happy to say that they did. The plugs are obviously intended for masking off holes prior to powder coating but they definitely work for sloshing tanks. I used the large blue for the 3/8" NPT holes and the smaller blue ones for the 1/8" NPT holes. I used a black one for the fuel vent tube.
    PXL_20210706_001834447.jpg
    It took three gallons of acetone before the stuff I poured out looked the same as what I poured in, making it a $75 task to get my tanks clean at today's prices. I did get out a bit of flakey residue which I captured in a paint strainer, so it's definitely an exercise worth going through.

    A question for the gallery:

    Still on my "I seem to have two of everything" theme, I have two different types of finger strainers. I have a pair of fine mesh and a pair of gravel catchers. At first I thought the gravel catchers were older but the bag has a Series 7 designation on the sticker so it can't be that old.
    PXL_20210706_001956051.jpg
    Which one is preferred?
    Kitfox 5 (under construction)
    Commercial SE/ME, CFII

  8. #248
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    Default Re: Project 5 build thread

    PXL_20210704_231928484.jpg
    I was able to spend about half of yesterday at the hangar working my white board list, and first up was fitting/locating the butt ribs. Late last week I managed to screw up two of my existing red powder coated butt rib fittings because the tip of my drill was wandering. Lucky for me I now had an opportunity to use the parts I bought in error (didn't realize I already owned them). The new ones were white but I figured by the time I ground the lengths to fit they would need refinishing anyway, and they do. I'll strip them completely and paint them red to match the rest of my upper cabin structure. I started my build session by drilling up the two holes like I had screwed up in my previous session. This time I used a center drill and then the #30 in my drill press, but doing so required I change bits constantly. Oh well, the price of 'pretty good'.

    It wasn't until I had everything clamped in place and ready to drill that I realized my standard length #30 wasn't going to reach in either of my drill motors. I knew I had a Kitfox supplied 12" bit at home and this was the time to use it. But I had about used up my day so I cleaned up my tools and went home for the night. The pic above shows what it looked like ready to drill.

    This morning I went back over to the hangar and drilled the butt ribs to match my steel fittings. Looking at my white board list it is quite obvious now that the next step is to epoxy varnish all the wood on the wings. My plan is to take them home for that since I don't think my hangar neighbors will be fond of the smell of the epoxy (it's a bit "hot"). When I made that decision earlier today it was starting to drizzle a bit. Since I use an open trailer to transport my wings I decided to occupy myself doing other tasks.

    So I pulled out the tub which contained my fuel system components. I removed the seat pan from the plane and installed my aluminum header tank (you guessed it, I sold the plastic one almost immediately when I got my project). The series 5 doesn't have the welded tabs like a series 7 does so I used Adel clamps. My first attempt was improvised and I had the ears of the Adel clamps all pointed inboard. That resulted in the tank being up fairly high. It might have been okay but I went through the series 7 manual and the ears of the welded tabs point towards each other. The manual also calls for AN3-4A instead of the AN526 (?) screws. I had all that stuff on hand so I corrected the orientation and hardware selection. This installation is much lower than the first attempt and sits perfectly level.
    PXL_20210705_215620870.jpg

    I then spent about an hour laying out fuel hose and measuring the lengths from the tanks to the firewall. When I visited Nate he had just removed all the hard lines from the header, through the fuel shut off valve and to the firewall bulkhead fitting, and replaced it all with -06 AN hose & fittings. I'm strongly considering doing the same. I should have taken pics of his routing but didn't, so I got to try different scenarios on my own. When I got home tonight I looked at Harlan Payne's build thread because I know he just routed lines. He used the hard stuff but I did see that he came to the same conclusion that I did, which is that the aft end of the fuel shut off valve should have a 90 degree fitting which points down, and a straight fitting going out the front.
    I also looked up my fuel valve to see what thread size it uses, and found that it's 1/4" NPT. So it seems like the shutoff valve is the most restrictive opening along the path.
    PXL_20210705_220840875.jpg
    With that planning done I test fit the seat pan to make sure I still have easy clearance between the seat and the header tanks. And since I was laying under the plane looking at stuff I grabbed my drill and drilled/reamed the holes for my baggage compartment floor. I think I'll copy what someone else here did and use hardware which comes up through the baggage compartment floor and is fixed in place, so all I have to do is spin off the nuts inside the baggage compartment to pull the floor out. I'll top it off by using some D rings at those locations.
    Kitfox 5 (under construction)
    Commercial SE/ME, CFII

  9. #249
    Senior Member jrevens's Avatar
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    Default Re: Project 5 build thread

    Quote Originally Posted by alexM View Post
    ...


    For the fuel filler holes I grabbed one of the gas caps (I have extras...) which I determined were either made wrong or for a different type of tank because the vent tube points at about 10 O'clock when viewed from above. With the defective gas cap in place I used one of the smaller tapered rubber plugs to close up the vent.

    PXL_20210702_011717766.jpg



    A question for the gallery:

    Still on my "I seem to have two of everything" theme, I have two different types of finger strainers. I have a pair of fine mesh and a pair of gravel catchers. At first I thought the gravel catchers were older but the bag has a Series 7 designation on the sticker so it can't be that old.
    PXL_20210706_001956051.jpg
    Which one is preferred?
    Hi Alex,
    I think you can find multiple posts on this forum describing carefully bending the vent tubes on the fuel caps for proper alignment. It actually works quite well... I don't see any obvious "twisting" or distortion where it (mine) was torqued. Install the cap and grab the tube close to the bend and slowly bend it into proper alignment. I doubt that your caps are "defective".

    As far as the strainer goes, I learned years ago that you want a fairly course finger-strainer at the tank outlet. It has less chance of clogging and interrupting fuel flow completely. It just needs to stop any fairly large stuff that may interfere with valve operation, etc. Think of it as the first stage in a multiple filter arrangement. I'd use the one on the right. I'm sure there may be differing opinions .
    Last edited by jrevens; 07-05-2021 at 07:02 PM.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

  10. #250
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    Default Re: Project 5 build thread

    John,
    Thanks for both of those tips. I would have thought that vent tube would twist right out of the cap if I put any load on it. Since I have two known good caps I've got nothing to lose by giving them a twist as you suggest. Then I can keep a spare cap in the plane for "someday".
    Kitfox 5 (under construction)
    Commercial SE/ME, CFII

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