Luked

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  1. Luked added a post in a topic Empty weights   

     
    Which engine does he have?
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  2. Luked added a post in a topic Tricycle gear information   

    Hi Chris,
     
    I actually removed it shortly after taking those pictures. I know some would prefer to leave it. There were several reasons I wanted to remove it though. For one, I wanted to save a little weight. I also want to change the front structure a little to add a seventh motor mount point at the bottom edge of the firewall. Also, I didn't like the way the socket hangs down below the bottom of the plane in front.
     
    In the end, I think it may decrease the value a little, but my plane will never be worth that much anyway. For one, it's going to have a non-standard engine. I'm really building it for my own fun, and cheap flying. I won't have that much into it when I'm done. If I ever sell it, I probably won't even get all of that back, but that's okay as long as it serves it's purpose while I have it.
     
    Luke D.
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  3. Luked added a post in a topic Empty weights   

    Hey Randy,

    When I started this thread, I was actually thinking, I hope this doesn't come off like I was saying the lightest planes are better than other planes. I just wanted to get a feel for what kind of weight I should realistically shoot for with my engine choice. Mine won't be the lightest either

    For the record, your plane is one of my favorite Avids. It just looks like a bush plane, and it's demonstrated that it's plenty capable.
     
    Luke D.
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  4. Luked added a post in a topic My Avid (model C+)   

    Nice plane Mark. Could you tell us more about it?
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  5. Luked added a post in a topic Tricycle to taildragger   

     
    OD is 1 5/8". Wall thickness looks like .0625". I don't have my digital calipers. Also, the powder coating makes it difficult to know exactly what the original dimensions were. Of course that would make it 1 1/2" ID. Hope that helps. I'm actually measuring all of the other dimensions. I'll try to make up a diagram showing dimensions.
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  6. Luked added a post in a topic Aileron pivot tubes?   

     
    What, no wind tunnel??
     
    I was just thinking of something simple to attach the torque tube to that could simulate a flexing wing.
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  7. Luked added a post in a topic Tricycle to taildragger   

     
    The only trigear parts I have are in the fuselage structure. I don't have any of the parts to the actual gear. I'll try to save it.
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  8. Luked added a post in a topic Tricycle to taildragger   

    I guess I just have a hard time dragging around that extra weight for no other reason than the idea that it might get used some day. For some reason I just don't like it. Call it a personal flaw
     
    Not sure if I could get it out of there in a very usable condition. I could try. I'd be happy to document the geometry of the thing, and wall thicknesses though so that someone could re-create it from new tubing though.
     
     
    Just for reference, here is a picture of my plane in the front. Sorry I don't have a better picture right now. My daughter recently stepped on my camera, and it doesn't work now. Need to get a new one.
     

     
    Here is a picture from a recent thread showing a taildragger.
     

     
     
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  9. Luked added a post in a topic Aileron pivot tubes?   

    Sorry Ed, I missed that. Binding would be a big concern with that setup. Maybe some type of test jig to test for binding in different load conditions could be helpful.
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  10. Luked added a topic in Avidfoxflyers General Hangar   

    Tricycle to taildragger
    I'm waiting on wing parts right now, so I thought I would work on something else. My Plane has the front mount for the trike gear. Has anyone removed this, and switched it to the tail dragger only style structure? Anything to watch out for? I'm about ready to remove it and put in the proper tubes to replace it, but thought I'd ask first. 
     
    Thanks,
    Luke D.
    • 9 replies
    • 1,274 views


  11. Luked added a post in a topic Aileron pivot tubes?   

    Hi Ed,   Since no engineers have answered, I'll add my 2 cents.   Disclaimer: I'm not an engineer. I did take 2 years of engineering classes when I was younger, so I picked up some basic concepts, but it was almost 20 years ago. I also think engineering is very interesting. Hopefully a qualified engineer will chime in though.   Anyway, I found this link using google:   http://www.engineeringtoolbox.com/torsion-shafts-d_947.html   If you scroll down to "Example - Shear Stress and Angular Deflection in a Hollow Cylinder", you can see how to calculate the maximum stress, and angular deflection for a hollow shaft. There is also a link on that page to shear modulas numbers for various materials. You can use google to find more.   I also found an online calculator that does the math for you:   http://www.amesweb.info/Torsion/TorsionalStressCalculator.aspx   You'll need to know the Ultimate Shear Stress (USS) for the material you are using. For steels, I think it's 60% of Ultimate Tensile Strength (UTS). You want to make sure that the calculations above don't put more stress on the part then the material used can handle. You'll also want to use some factor of safety.   You mentioned flexing, so I assume you mean angular deflection. Long shafts can flex out of alignment, but that's more difficult to model, and if your torque tube is supported at multiple points it probably won't be an issue. Anyway, the example in the link above covers angular deflection.   To me, the most difficult part of these kinds of problems is not determining if a part is strong enough to withstand a particular load, but determining what types of loads the part will experience, and how severe. I guess that's kind of the art of engineering. How strong should a bicycle frame be? How high of a jump will a kid take it off of?   The load on your torque tube could be a fair amount different than the load on a stock flaperon. If it is connected to the aileron by a pushrod, the length of the arm on the torque tube and the length of the control horn will affect the torque in the tube. If your tube is directly driving the aileron (like a flaperon), it could still be different from the stock flaperon because the flaperon might be getting some aerodynamic balancing that the aileron is not. Also, differences in chord length would cause different loads.   Basically, figuring out the loads is the hard part to me, calculating the stresses and deflections is easier. That's probably enough rambling. Hopefully that's at least a little helpful. Like Paul said, I'm not an aircraft designer. My brother happens to be a civil engineer, so at least on structural problems, I can have him double check stuff I do, and he can tell me if I'm on the right track or not.   Luke D.   Edit: I see you are running the aileron torque tube through the flap torque tube. Sounds like a Tailwind. Maybe you should see if you can have a look at a set of Tailwind plans. I think you can still buy them too.
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  12. Luked added a post in a topic Continental in Avid MK-IV?   

     
    Okay, I wasn't sure if the stretch Larry was talking about was something different than what I have. He mentioned the stretch being right behind the cabin. Mine is stretched closer to the tail. Maybe he was just describing the same thing.
     
    On the fuel burn, I guess you can't expect that great of fuel econemy from an engine with a carburetor that's about as advanced as the valve in a toilet boil
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  13. Luked added a post in a topic Continental in Avid MK-IV?   

    Leni, I guess I shouldn't have brought up the baggage idea until I had more figured out. It was mainly just to say that I'm not planning to have only a stock baggage area. I probably won't have a ton of useful load, but I might want to stick some light weight bulky stuff in there like some sleeping bags or something.
     
    Larry, my plane's got the tail extended 16". I'm not planning on doing any more stretching at this point, but I'm curious about the stretch right behind the cockpit. What are the advantages over the stretch back by the tail? Or, is this done in addition to the stretch at the tail?
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  14. Luked added a post in a topic Continental in Avid MK-IV?   

     
    Well, I remember you mentioned how nice it was having a large baggage area when I first posted about my project. So, I'm planning to have a larger than stock baggage compartment, but it should weigh a lot less than what was in the plane, and be much closer to the CG... Don't know if I want to share details yet though in case the idea is a flop 
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  15. Luked added a topic in Avidfoxflyers General Hangar   

    Continental in Avid MK-IV?
    I started another thread asking about real world Avid empty weights because I was concerned about my empty weight if I go with a Continental engine that is heavier than the plane was designed for. The question of the trade offs of using a heavier engine came up, so I thought it might be good to start a thread on the subject. It might be interesting to others too, or people searching the archives in the future.
     
    The other thread about empty weight: http://www.avidfoxflyers.com/index.php?/topic/2805-empty-weights/
     
    I don't want to come off sounding too defensive about my plan to use a Continental, but I have put quite a bit of thought into it. Also, everyone's situation is different, and the trade offs that work for one person might not be right for someone else. I know the Continental won't be the most popular choice of engine for most people. I have to decide if I will be happy with the trade offs when all is said and done, and I have a finished airplane.
     
    All that being said, I'm at an early enough stage that I could still change my plan (I'm only part way down the Continental road at this point), so I'm open to other peoples thoughts. If I do put a Continental on the front of my plane, I want to do it with my eyes wide open to all of the potential negative aspects.
     
    I'll give a little background on my thinking. When I bought the partial kit, the previous owner had already lengthened the fuselage by 16". His plane had been to put an O-200 on. In addition, he had added extensive sheet metal to the area behind the seats that extended most of the way back on the tail to make a huge baggage compartment. In addition to this, he had built the wings to be "convertible" from speed wings to long wings with removable tip and flaperon extensions. also, I measured the washout on the wings that he had already built, and they had slightly over 2" of washout on the short wings alone.
     
    This whole thing seemed like a recipe for hugely overweight Avid with poor performance. I basically considered the wings a write off, and decided I would build new ones. Having the stretched tail made me think that a smaller Continental might be a decent fit, and might work with my budget. My first thought was an A-75 with no electrical. This is about the lightest Continental that would be in the right HP range. My thinking was that it should perform like a 582 powered Avid that's carrying some extra weight.
     
    The more I got to thinking about it, I wondered if I would regret not having an electrical system. I am also considering a C-85 with lightweight accessories. I already have a flanged crankshaft that will work for either engine. In any case, I am planning to keep the airframe as light as possible (a tall order I know) because I know I am already going to be suffering from having more weight than what was intended.
     
    Anyway, any additional information would be welcomed and appreciated, and better information leads to better decision making.
     
    Luke D.
     
    Edit: forgot to add that I've already removed all of the extra weight that the previous builder added that was not stock. More weight saving ideas are in the works.
    • 13 replies
    • 1,177 views


  16. Luked added a post in a topic Empty weights   

     
    This was pretty much my thinking. I put some more details in a new thread here:
     
    http://www.avidfoxflyers.com/index.php?/topic/2807-continental-in-avid-mk-iv/
     
    Chris raised some really good points. I don't think he knew some of the details about my project (that it was stretched, or that I was considering the smaller Continentals for instance). His points are still very valid though. Good food for thought.
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  17. Luked added a post in a topic Empty weights   

    Hi Chris,   Thanks for such a detailed reply. I didn't post exactly the same thing as before, because I didn't even remember exactly how I asked it the first time. After I re-posted, I remembered a few things I had forgotten, but decided to just leave the simpler post.   I'd like to discuss the pros and cons of certified engines in the lighter Avid and Kitfox type planes. Maybe I should start a thread just about this subject. Quite a few people have listed their empty weights on this thread, and I think it could be a useful thread for the future if people just keep adding empty weight info to it.   No hard feelings at all about your advice. I welcome it. I've agonized over engine choice quite a bit already.   Luke D.
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  18. Luked added a post in a topic Empty weights   

    That was quick. Excellent! Thanks guys. Any others would be appreciated as well.
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  19. Luked added a topic in Avidfoxflyers General Hangar   

    Empty weights
    I guess I'll re-post the question I asked earlier today right before the site went down. Could anyone share some real world empty weights? Any additional information that relates to weight would be helpful too (engine, custom features that affect weight, etc.). I searched for this, but didn't come up with a similar thread.
     
    Now that I'm about ready to start building my Avid, I'd like to set a weight goal. I'm guessing that I'll be somewhere between the 912 guys and the Subaru guys. That's assuming similar airframe to my MK-IV (Avid A-IV, or KF I-IV).
     
    Thanks,
    Luke D.
    • 44 replies
    • 8,284 views


  20. Luked added a post in a topic sorry guys but we got hacked   

    No problem. Thanks for your efforts to keep the site running!
     
    Luke D.
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  21. Luked added a post in a topic Kitfox wings for Avid MK IV   

    Thanks for the tip Ed. I'll refer back to this when I get to that point. Wouldn't want to get it upside down. I think I have a full scale drawing of the leading edge in the manual I got from Kitfox, so I could probably make the templates myself like you did.
     
    Luke D.
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  22. Luked added a post in a topic Kitfox wings for Avid MK IV   

    Thanks guys. I assumed it must be an optional thing. I included the PVC extrusion in my list.
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  23. Luked added a post in a topic Kitfox wings for Avid MK IV   

     
    Hey Ed,
     
    Thanks for all the extra info. I just realized you added more. The more the better. It's all interesting. Everything you said makes sense to me. My thinking is not so much who is right, but what configurations are well documented, have been around a while, and have a successful track record in the field. I'll probably just go with a fairly conservative approach (stock MK IV structure). I don't want to be wondering if things are going to hold together down the road. 
     
     
     
    I've got one more question for any Kitfox experts. I saw some pictures of a KF wing being built, and it had a fiberglass leading edge. Is this standard, or an option? The build manuals I have don't have any mention of this that I noticed. I was hoping to keep things simple and light. In other words, just fabric on the leading edge. Thanks for any info you can give.
     
    I spoke with Kitfox yesterday, and they told me to email my list of parts for pricing. Just waiting to hear back now. They are probably a little busy winding down form SnF.
     
    Luke D.
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  24. Luked added a post in a topic Kitfox wings for Avid MK IV   

    I don't have any experience with the Avid speed wing airfoils, so I'll leave that to others who do.
     
    EDMO PMed me with some things to look out for on the struts and strut attach points though. After talking about this with him, I went to the airport where my wings are to check some things. I thought I would just add what I found. Most of the experienced Avid guys probably know all this, but it may help someone else like me down the road.
     
    Note: all of my references to the KF manual are from the two that I have which are:
     
    Kitfox Super Sport wing Assembly / REV A / Date:05/11
    Kitfox Super Sport wing Assembly Supplement / REV A / Date:05/11
     
    Strut attach location - I measured my pair of short wings, and the struts attach at 80" (from end of tube to bolt hole). This is also what the Avid manual shows for HH wings (144" spar tubes). The KF manual shows 95" at the front spar, and 94.5" at the rear spar (162" spar tubes).

    Strut attach bracket lug spacing - Avids only have a rod end on one of the four struts, the three without rod ends are just slightly wider than the strut tube at the end. Mine appear to be 1" wide. The spacing on my strut attach brackets also appears to be about 1" wide. The pictures in the KF manual look like they have a narrower spacing. It's just a little wider than the rod end, so that a washer can go on either side of it.

    Right now I'm thinking of modifying the ends of my struts to accept rod ends so that I can use them. I figure that I can build my wings to HH dimensions, and everything should line up that way. Also, the shorter HH wing length should keep everything basically stock structurally. This seems like the simplest solution.

    The other option would be to make new struts to the KF dimensions, and build the wings to KF dimensions. Or, I could buy KF struts, and see if I can modify the bottom end to work with my Avid fuselage connection. This option seems more complicated, but might mean a little better STOL performance with the slightly longer wings.

    Thoughts?
     
    One of the strut attach points

     
    Measurement from end of spar tube to strut attach point.

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  25. Luked added a post in a topic Kitfox wings for Avid MK IV   

    Yeah, good point about avoiding ethanol. Still it's nice to know your tanks won't desolve if you get some in there. The KF tanks sound like to way to go though.
     
    Ed, I think the current wings just have too much twist to correct very easily. From what I measured, they had a little over 2" of twist, and these are speed wing length. If I extend them, the twist will get worse. I thought about trying to tear them apart to re-use what ever I could, but the more I thought about it, the more I started thinking I probably wouldn't end up salvaging that many usable pieces.
     
    I don't know much about the history of the KF flaperons (I think I might have read that story about KF changing back and forth on the airfoil though), but I have the latest build manual for the SS. It's kind of interesting when you look at the CAD drawings in the manual. They definitely look pretty symetrical. I wouldn't say that they are perfectly symetrical though. If you put a straight edge on the diagram from the leading edge to the trailing edge, the chord line goes below the center of the torque tube by a fair amount. On the other hand, it's sure not a flat bottom like my Avid flaperons either.
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