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Thread: Project 5 build thread

  1. #101

    Join Date
    Feb 2020
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    149

    Default Re: Project 5 build thread

    A few pictures going in to the weekend and hopefully some more along the way. I have the balsa pieces glued on to the ends of the horizontal stab and elevator, rough sanded, filled with Super Fill and sanded some more. I've decided to wait until I pull the stab/elevator off the plane to finish shaping the tips because access will be so much easier.

    Before that
    My plan is to measure and mark the rudder cables (I may cut and swage them as suggested in the tips section and just get it over with), and I still have to set my center hinge bearing on the rudder. Really looking forward to that step. I've also got to fix the rudder over travel issue because the PO trimmed too much off the horns. I've read of some elegant solutions here on the forum, so thanks to whoever screwed this part up before me.

    I'm also going to follow the rigging instructions to set up the horizontal stab and elevator to make sure there are no issues with that. I have already determined that the two welded tabs at the very back (not used with the speedster tail) do not interfere with the elevator travel at the extremes of stab trim. It's that kind of stuff that I'll be looking for by following the rigging instructions, but it should also allow me to lock down some of the push rod adjustments and not have to mess with them later. I'm not going to celebrate with torque seal on them just yet though.

    Engine mount
    Since I'm going with the weirdo engine I'll need to obtain an engine mount. The US distributor that I'm working with suggested I design my own, and sent me some pictures to use as inspiration. I've never designed an engine mount before but I have designed airplane parts most of my career so I decided to give it a try. I measured up my fuselage attachment locations, spent a lot of time staring at/measuring the 912 mount I have, looking at/measuring the mount on my Citabria and then looking at a whole lot of pictures of radial engine mounts. I also had a nice long conversation with Ted Myers who is installing a nine cylinder Verner on a Kitfox 7.

    Back the truck up a sec
    I have to walk back a statement I have probably made a few places, and that is in regards to the plane Ted is working on. I was under the mistaken impression that the plane Ted is doing the work on was a previous factory demonstrator plane. Though the paint schemes are similar, it is not the same aircraft. The plane Ted is working on is one some of you might have seen on Barnstormers a year or so ago, a plane that was in the Rotec booth at Oshkosh 2019 (assuming I finally have my story straight).

    Moving on
    I now have a fully parametric model of a ring-type mount which can be adjusted any way I need it to. I've done 3D CAD since the late 80s so this kind of stuff is what I do. I own an older (legal) seat of Solidworks but it's on an old laptop that is weak in the knees. So I downloaded the EAA Solidworks 2020 onto my new laptop and gave it a spin.
    Scarlett 7U mount.jpg
    This is one of those objects that is difficult to view from a single angle and have it look right. As modeled I can shift the engine forward or back, raise it up, add some thrust angles, change tubing diameter/wall thickness and recalculate the whole thing in seconds.
    I used the "Weldment" function in Solidworks which is pretty amazing, and I did some finite element analysis which showed the mount could shrug off +6G with a 1.5 factor of safety. Not an exhaustive evaluation but at least it is a start.

    The Verner uses the same Lord mounts as the Rotax 912 and some Continental O-200 installations, and I just happen to own four of the mounts already.

    A couple of days ago I sent the CAD model to the same welder Eric used on his Barn Find recently. Not only is his welding a thing of beauty, the guy welds most/all of the engine mounts for Van's so he probably knows a thing or two. He's going to review my design and sling dirt at it until I get it right.

    Getting my hands dirty again
    All that computer stuff is fine if you have the stomach for it, but we're here to build airplanes. I've been itching to get this next task done for a while. My fiberglass seat pan has never been a thing of beauty. Back when I was spending time at my local body shop to clean up my fuselage after welding and powder coat repairs I picked up a can of two-part bed liner. Of course I waited until the temperatures dropped to try it out right? I had my son sand the white gelcoat until it was paper thin, and I ran out and bought a space heater for my garage. My seat pan has the optional storage trays already mounted so I masked them off and cleaned the whole thing very carefully with alcohol. Out of excuses, I hosed on the bed liner last night.
    PXL_20201107_002550360.jpg
    Before
    PXL_20201107_005645842.jpg
    After
    And no, I didn't paint it sitting there. In that second image it is still very wet and flashing off. There were a lot of acetone fumes so I got the heat going and left it alone. The wet clumpy look calmed down considerably and I'm pretty happy with way it turned out. The stuff I used cures in one hour but it takes three days before you can really give it the business. I'm going to weigh it today and see how much the bed liner cost me in useful load.

    Window and door trim
    With the seat about ready to bolt in I turned my attention to the aluminum pieces around the door frames and the window. These were actually the very first pieces I did anything with when I first got my project. I can recall being a bit overwhelmed at how they were supposed to fit and not really happy with their condition. They had been installed by the first builder and removed by the second builder. They were not perfect when installed and removing them didn't improve them at all.
    PXL_20201107_013430108.jpg
    Some of the pieces actually fit very well and some are way off. After messing with them for a few hours the other night I decided to order all new pieces from Kitfox, and emailed in my RFQ yesterday. The pieces that are in good shape will serve as patterns for the new pieces, and the bad pieces will serve as a guide on what not to do.

    I made a discovery last night that I was not stoked about. A couple of weeks ago I brought home my side stringers and cleco'd them in place. There was tape around the ends and they still needed to have the old structural adhesive cleaned up. Well last night I pulled the tape off and found that whoever cut those side stringers screwed up the right side and cut the tube too short. They cobbled together some kind of fix involving a short aluminum inner sleeve, a piece of wood dowel and a wad of Hysol.

    I figure shipping a couple of 9' long pieces of aluminum tube from Idaho will cost more than the tubing, so I've sent a request for quote to Metal Supermarkets about 20 miles away, who I have done plenty of business with in the past. I can just drive there and get the pieces and be back in business quickly.

    I'm still resolving my landing gear situation (I need some more inches to clear a big prop) and I have started looking at what I'm going to do for my panel. With any luck I'll be taking the fuselage to my hangar soon and starting my wings by Thanksgiving.
    Last edited by alexM; 11-07-2020 at 10:29 AM.
    Kitfox 5 (under construction)
    Citabria (flying)
    Commercial SE/ME, CFII

  2. #102

    Join Date
    Jun 2020
    Location
    Toledo, WA
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    Default Re: Project 5 build thread

    That seat pan looks really good. I like that idea a lot; expect me to steal it!

    I have a crate sitting at Kitfox that's going out next week. It already has a 10' elevator push-pull tube and two PVC strut fairings in it, so the length wouldn't be an issue. You might ask Debra if she can add your tubes to my crate. We could meet halfway for a taco and hand them off. Or, if they'll fit in your Citabria, you could come and get them.
    Eric Page
    Building Kitfox 5
    Member: EAA, AOPA, ALPA
    ATP: MEL / Comm: SEL, Glider / ATCS: CTO
    Map of Landings

  3. #103

    Join Date
    Feb 2020
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    Tacoma, WA
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    Default Re: Project 5 build thread

    That's a generous offer Eric, thanks. You had me at "taco". I just left a voicemail with Kitfox to see if I can get some parts in your crate. I'm happy to support the factory when possible.

    I just weighed my seat after curing and the bed liner cost me 4.4 ounces. It's actually less than that but I didn't weigh the seat before sanding the gelcoat down.
    Kitfox 5 (under construction)
    Citabria (flying)
    Commercial SE/ME, CFII

  4. #104
    Senior Member rv9ralph's Avatar
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    Greenleaf, ID
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    Default Re: Project 5 build thread

    I have a question on coating the seat pan with bed liner... I you are using upholstery, it is usually attached to the seat pan with velcro, covering the seat pan. It is usually attached to the seat pan with velcro. Will the velcro stick to the bed liner?

    Just thinking.

    Ralph

  5. #105

    Join Date
    Feb 2020
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    Tacoma, WA
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    Default Re: Project 5 build thread

    I considered that for a while. I'm honestly not sure what my upholstery will look like or where the velcro would go, so it was hard to plan for. It would not be difficult to mask off those locations once I know where they are and sand the bed liner smooth.

    I will say that for any application where my employer uses "hook and loop" we don't trust the sticky side so we glue it on with epoxy. In that case minimal sanding would give the epoxy a sufficient surface.
    PXL_20201108_062224440.jpg
    Here's a poser shot with the seat pan in place

    PXL_20201107_213703055.jpg
    Speaking of poser shots, I brought my boot cowl home from the airport today and did a very temporary install of my firewall, boot cowl and the 912 engine mount. These parts are all back safely in the rafters of my "shop" now. While I like sitting in the plane and making airplane noises, I really like getting out parts that are way down the road and getting an idea of how they will be impacted by what I'm doing now. It is also a confidence booster by making the plane look more done.

    I can see there is lots of trimming and fitting in my future. It is still not clear to me at all how the bottom flap of the firewall is supposed to attach to the fuselage where it extends back several inches. I might have added welded tabs if I knew about this at the right time. It makes me even more glad that I won't have to get back in there if I need to remove the rudder pedals for any reason.

    The majority of the work I did yesterday was to start at the very front of the plane (without the boot cowl, firewall and mount) and get everything truly ready for setting rudder cable length. I started by replacing the AN526-1032R12 fasteners with *R10s. I replaced them mostly because they've been in and out of the plane so many times the Philips heads aren't as pretty as they once were. I dropped down to the -10 length because the -12s stuck through my nutplates so far they ran a risk of contacting that flappy thing on the firewall. I still have more than 3 threads with the -10 length

    Next I went through every fastener on the rudder pedals and rudder cables, replacing washers as needed to get 1-3 threads protruding on all the nyloc nuts, and to position all the castle nuts for ideal engagement of the cotter pins. Finally, I installed my first cotter pins.

    I celebrated by making a mess with a brand new tube of torque seal. I'm really only using it to mark the fasteners that shouldn't have to be disturbed again. Of course I marked my fingers, pants, etc. Good to go.

    I'm going to continue back through the flight controls all the way through the flaperon mixer while my floor boards and seat are out of the plane. THEN I'll be ready to mark and possibly cut my rudder cables, set my elevator travel, etc.

    Today I probably won't get much done because the annual on my Citabria should (hopefully) be signed off this morning. I'm supposed to take part in a formation fly over for a WW II veteran's 98th birthday.

    Fortunately it's severe clear and very cold - perfect flying weather.
    Kitfox 5 (under construction)
    Citabria (flying)
    Commercial SE/ME, CFII

  6. #106

    Join Date
    Feb 2020
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    Default Re: Project 5 build thread

    123993942_3802914609728061_5113206836107839517_o.jpg
    Pic taken last weekend.
    Most everyone bailed because of the winds, but there was a P-51 which made the whole thing worth it.

    During the week I got my door trim pieces from Kitfox delivered. Earlier in the week Deb from Kitfox called me regarding putting my stringers into Eric's crate. It was my first time talking to her (very nice and knows her stuff). Turns out Eric's crate was only 8' long and the stringer tubes are 9'.
    I had already arranged to procure 1/2" aluminum tubing locally, and had matched my order to the stringers that came with my plane (which were 0.063" wall), but Deb said they used tubing half that thick. My will-call order was already cut but when I got down there I asked about thinner wall tube. If I went with 6061 instead of 6063 I could get thin wall tube, and of course lighten my wallet a few ounces. I went home and ordered a new set of tubing, and picked that order up a day later.
    Seems trivial but readers will be used to me slapping things on my scale-of-truth. Going with the thinner wall tubing saves me about 1.25 pounds.
    I should mention that weight difference includes a third piece to use as a belly stringer. The series 5 calls for a piece of wood. I do have wood stringers but I only have four pieces and those are intended for the wings (100% likely I'll also go with the SS type aluminum tubes in the wings as well).

    Two nights ago I spent the evening with my heat gun and scraper, removing the traces of Hysol from around the door frames and going over all the bonding surfaces with a scotchbrite wheel on my angle grinder. It was one of those nights where you reach a stopping place but then pick up one more piece to see how it fits. "Squirrel"! Next thing you know it is past midnight.

    PXL_20201114_002852186.jpg
    I've read about how this can be a tough job, and the pieces that came with my project show some areas where it could have come out better. The instructions say to start on the window frame, so I grabbed the pieces that fit the best and used them as a pattern. I found it easiest to use a good part from the left side to clamp to the stock and make an opposite hand part (rather than another left hand). After messing with choices of the correct tools to use I finally arrived at the combination that works best for me:

    -Sharpie pen to eyeball the lines where I will cut, then a scale and my scribe to mark the line on the sharpie mark (makes it easy to see because of the contrast)
    -Right/left aerospace tin snips to cut pretty close to the line,
    -2" sanding disc on my angle grinder to fine tune the shape and get in the places the tin snips can't,
    -2" scotchbrite wheel to debur edges, put some small radii on all the corners.
    -2" cutoff wheel on my straight grinder to make the slots. I should admit that I tried several methods which weren't working out well before I grabbed that cutoff wheel and made nice slots in seconds.
    PXL_20201114_071556087.jpg
    Last night I put in several hours completing both right and left window frames. Happy to report that I did not cut anything too short and I did not make any opposite hand parts by mistake (there is huge potential to do so). Having the old pieces on hand sped this up considerably vs. raw stock and nothing to compare to. And of course once you have a part you know is good, making an opposite from that part goes even quicker.
    PXL_20201114_071609274.jpg
    I'm going to complete the rest of the door frame pieces before drilling the holes in them, and I'll be cutting/drilling my stringers. There will be some very minor fitting where I left just a hint of extra material where things overlap.

    It's going to be a good weekend, with Hysol and rivets to be consumed.
    Kitfox 5 (under construction)
    Citabria (flying)
    Commercial SE/ME, CFII

  7. #107

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    Feb 2020
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    Default Re: Project 5 build thread

    I did put in several hours and I'm happy with my progress but, well - no Hysol or rivets as I projected.
    PXL_20201115_171808575.jpg
    After being happy with my progress with the window frames I thought I was on the home stretch with the rest of the door angles. Not so much. I think I spent half of saturday fine tuning the location of those door angles so that I could drill holes and insert Clecos and everything would sit where I wanted it to. Then I spent the rest of the day trimming and fitting the left side seat back angle, and also cutting fitting and drilling the left side stringer.

    I found it difficult to fit the pieces with minimum gaps and it took me quite a while to work out the overlaps and make sure I had sufficient edge margins. I looked on several build threads and apparently I'm the only one who struggled with the door angles. In several threads they just show up miraculously with hardly a mention. I did find good images to go by on the tropicaltuba website, and also the one's John McBean posted at some point.

    After a long day today I can say that I've got all but the very last angle (the short one at the very front). I also have the stringers ready for bonding/riveting except for the very tail ends, which I left slightly long.

    Now that I know all these parts fit nicely I can work out my adhesive strategy. I've got some final deburring and prep to do before bonding. Hoping I can get that done tomorrow night.
    PXL_20201116_015326718.jpg
    No scrapped parts, no poor edge margins, no extra holes and no trips to the ER.
    Kitfox 5 (under construction)
    Citabria (flying)
    Commercial SE/ME, CFII

  8. #108

    Join Date
    Feb 2020
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    Default Re: Project 5 build thread

    A few days with no hands-on time, but lots of reading and surfing. As I planned my way forward with the door angles I read up again on bonding dissimilar metals together, and also pondered the body and fender work in the corners.
    As flashy as the clad aluminum looks, the Hysol and Superfil in the corners will mess up the look, and fabric will cover it all later anyway.
    I read up on my specs and decided to hit the parts with a maroon Scotch Brite pad. I looked locally for 5" velcro discs for my random orbit sander but no go. I found them on Amazon but the delivery date was 2 weeks, and only if I wanted $94 worth of them.
    I found them on the R.S. Hughes web site and hoped I could go pick them up, but they didn't have any at the store. So I set up an account, ordered 5 discs (for cheap) and then made the mistake of looking at the rest of the web site. It's hard to believe how much self control I exercised by ordering only the 5" pads, but it was only because the other items in my car showed a later shipping date and I didn't want my pads sitting in a box waiting for the other items. They came yesterday

    Parts prep
    I put my hands on every door angle (12 pieces), the side stringers and the belly stringer. I deburred all the holes with my whirligig thing, dehorned every edge, sharp corner and tool mark and then got as many surfaces as I could with the 5" random orbit, just enough to brake the shine. I used my fingers and a piece of maroon pad to get the insides of the angles, which are of course the bonding surfaces. I cleaned up all three stringers by hand with the Scotch Brite pad.
    I cleaned the parts with acetone and kept at it until the rag came clean.

    Etch and Alodine
    It was time to get my engineering geek on, so out came the Bonderite C-IC 33 etch and M-CR 1201 Alodine. I needed something that was long enough to fit the longest parts (about 29") but was a small enough volume that I didn't need to waste chemicals. Did you know that no one does wallpaper anymore? Who knew? I hoped to find those long, narrow tubs they use to wet stuff out, but no such luck.
    Best bang for the buck was some shallow storage tubs at Walmart. Much wider than I needed so I just tipped them up at an angle. I had just enough depth to do one set of six parts at a time.
    The Alodine specs say it needs to be between ambient and 100 degrees. Well I was doing it outside and today it wasn't particularly "ambient". I started with hot tap water since the chemicals were cold and they would cool quickly as I used it.

    I scrambled for the better part of an hour. Both chemicals say they should be applied for 2-5 minutes, and they need to be thoroughly rinsed after each step (and dried too unless they're going straight into the next tank).
    I went with 4 minutes for both. I etched the first set of 6 parts, rinsed them then threw them in the Alodine. I was able to stagger my timing with the next batch so that I was constantly rinsing or swishing parts. When done I dried the parts (they can get splotchy if you don't, which doesn't really matter but hey).

    I got those completely done, and then went after the stringers. Obviously the 9' stringers weren't going in my 30" tubs, so I stood them vertically and kept them wet as high as I could reach and swapping ends every 45 seconds or so. As they say "rinse, repeat". And dry.
    PXL_20201121_002749389.jpg
    PXL_20201121_002844991.jpg
    I wish I could have taken a picture after etching but before Alodine but I was too busy. The parts are super clean and almost white. Any pictures taken of parts on this work bench have zebra stripes because the bench light is an LED and the camera sees something the naked eye does not.
    Kitfox 5 (under construction)
    Citabria (flying)
    Commercial SE/ME, CFII

  9. #109
    Senior Member rv9ralph's Avatar
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    Aug 2014
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    Greenleaf, ID
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    Default Re: Project 5 build thread

    You definitely went the full measure to alodine the parts. One method of soaking the parts is to fabricate a trough by laying 2 pieces of lumber (your choice) a few inches apart blocking the ends with a couple more blocks of wood, then covering with plastic to create a trough, then fill with the chemicals. Another method is to spray the Alodine onto the material, keeping it wet until it has done its work, then rinsing. To dry, blow off with compressed air.

    To prep the material, you can clean with alumaprep, scrubbing by hand with scotch brite. Instead of using an orbital sander, get a pneumatic angle grinder with a 3" rolo disc mandrel. Use rolo disc scotch write pads to do the work.

    Ralph

  10. #110

    Join Date
    Jun 2020
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    Toledo, WA
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    Default Re: Project 5 build thread

    Another good option is an appropriate length of PVC pipe with a cap glued on one end. Insert parts and Alodine, cap the open end, hold a rag over the cap to catch dribbles, and commence sloshing.
    Eric Page
    Building Kitfox 5
    Member: EAA, AOPA, ALPA
    ATP: MEL / Comm: SEL, Glider / ATCS: CTO
    Map of Landings

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