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About cr125r847

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  • Gender Male
  • Location Nowthen, MN

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cr125r847's Activity

  1. cr125r847 added a post in a topic Fuselage landing loads (Kitfox IV) and cabane gear   

    Looks fine to me. The attachment in the cad drawing would produce a positive camber twisting force as weight is applied to the gear.
    His bungee tube attachment is in line with the center of the axle and also gussets the front and rear gear leg tubes to the axle like other cabane gear I have seen for Kitfoxes and Avids.
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  2. cr125r847 added a post in a topic Full Lotus Float Air Bladders   

    Sorry, I should have updated the thread. I was not able to find anyone that would sell a small quantity of the polyurethane TPU film. I ended up buying the 0.3mm thick TPU film on Aliexpress for a fairly reasonable cost. Sourcing the tetrahydrofuran solvent to make the glue was the next problem. I think the solvent was $30 and shipping another $30 or $40 from a lab chemical supply house.
    The Full Lotus manual recommends dissolving small pieces of the TPU film in the solvent to make a thick glue. This can be used to seal up pinhole leaks or as a glue to attach patches over larger tears and holes. I got all of the blown out bladders repaired and now just need to locate a couple pinhole leaks in some other bladders. They will be an easy fix once I find them.
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  3. cr125r847 added a post in a topic stock round rudder   

    Here are a couple pictures comparing model C and Mk 4 control surfaces.

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  4. cr125r847 added a post in a topic Matco 8 inch wide tailwheel   

    It says not for highway service. Doesn't say anything about airplanes.
    I have had my eye on these as well. Just need to find a cheap aluminum 4" wheel that would fit the tire and we would be set.
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  5. cr125r847 added a post in a topic Flaperons not lined up   

    That was Brooks that bought an A model Avid and sold it last year. His plane was was a lot closer to flying condition than the basket case I brought home.
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  6. cr125r847 added a post in a topic Flaperons not lined up   

    It has been a long time. I'll try to get a new post started to show my progress.
    Long story short, the more I tore into the plane, the more I found wrong with it and it ended up needing new wings and a complete rebuild. I don't regret buying the plane as it has been a great learning experience, but a ton of work.
    And yes, I did visit Jim a couple years ago and am looking forward to stopping by again after I get the Avid flying.
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  7. cr125r847 added a post in a topic Full Lotus Float Air Bladders   

    My searching found a bunch of manufacturers of the polyurethane film but no distributors. A local plastics film company tipped me off to a film distributor and I'm waiting to hear back to see if they will send me a sample and quote.
    Your "polyurethane air bladder" search brought me to the kite surfing crowd. Another hobby I know little about but apparently they use polyurethane air bladders on the kites so maybe there are some diy people that have leads to get the film.
    Anyway, thanks again for the ideas.
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  8. cr125r847 added a post in a topic Full Lotus Float Air Bladders   

    Thanks Chris. I have not heard of kayak float bags before. That is exactly the information I was looking for.
    Now I need to find out where I can buy the material without buying a 1000 yard roll.
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  9. cr125r847 added a topic in Avidfoxflyers General Hangar   

    Full Lotus Float Air Bladders
    I bought some older Full Lotus floats this weekend that have six of the rear air bladders needing replacement. Replacement bladders are available from Full Lotus for $124 each, but they seem like they would be easy to make for a lot cheaper. The bladders are just a single sheet 0.010" thick folded over and heat sealed on the three sides. There is also a circular reinforcement where the valve stem goes through the bag.
    Does anyone know what type of plastic these are made out of? I was originally thinking window vinyl, but they are stretchier and more rubbery feeling. My guess is they are either polyurethane or polyester TPU plastic film and I have found a few manufacturers of these types of plastic, but no distributors. It would be best if I could find an end user of the film where I could just buy a small quantity.
    It would be great if anyone has any info or leads. I'm planning on calling some of the companies that make the plastic to see where it can be purchased.

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  10. cr125r847 added a post in a topic Vortex Generators   

    You're right, it was a rude comment that should not have been posted. I shouldn't have lowered myself to name calling.
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  11. cr125r847 added a post in a topic Vortex Generators   

    Deleted my insensitive comment, but his impression remains. He had some really interesting testing but in my opinion could have presented it in a better way. There are some awesome videos on YouTube but maybe his are not for me. Thanks anyway for sharing!
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  12. cr125r847 added a post in a topic Vortex Generators   

    Maybe my comment was a bit harsh but I cringed when the grown man in the video said how scary it was to hold his plane in a stall. And then nothing happened. If he was scared the plane was prone to entering a spin, let's not be making YouTube videos and instead focus on flight testing the plane. I took his comment that he was scared to hold the plane in the stall. In that case, he'd best go talk to an instructor instead of the camera in the plane.
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  13. cr125r847 added a post in a topic Ribs and spar material   

    Pictures, or it didn't happen  I'm curious how you are building the ribs. I only have one wing to rebuild but if I were doing both I would have made composite ribs. 
    You must be just weighing the main part of the rib between the spars without cap strips or tails. I am just finishing gluing my ribs up and they weigh 9.3oz with without the flaperon tail and 10.3oz for the long ribs with the tail. The short ribs behind the gas tank are 3.4oz and 4.1oz. Total weight is 6.35lbs in each wing. I'm using the 5mm 10-ply plywood for the main rib and 3mm 5-ply for the cap strips. I'm thinking composite ribs would easily save 25% in weight and similar cost vs buying the plywood from Aircraft Spruce. 
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  14. cr125r847 added a post in a topic New Wing design.   

    I'm not an expert, but from what I understand, a sharp leading edge can get you into trouble with nasty stall characteristics and it's best not to mess with the leading edge unless you know what you're doing. Extending the trailing edge shouldn't make much of a difference. With that said, the KF4 uses the Ribblett GA30U-612 airfoil and the coordinates are posted on the internet. Why not plot the airfoil with a 2" longer chord and you will have a known airfoil and not be left wondering how your changes will affect the flight characteristics? I can plot it out in CAD if you need. Just get me the chord length.
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  15. cr125r847 added a post in a topic Getting started/setup for Welding?   

    I bought an AHP AlphaTig 200X last year and have had very good luck with it so far. I hate buying Chinese, but a comparable Miller or Lincoln would have cost 5x more and out of my price range.
    If you go the Tig route, I would recommend one that is capable of AC and DC. That way you can weld aluminum and any other weldable metal.
    Then take some time and watch Jody's videos on his weldingtipsandtricks YouTube channel. He does a great job explaining the settings and proper techniques.
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