Christavia wing flaps

Discussion in 'General Experimental Aviation Questions' started by namr82race, Jan 23, 2020.

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  1. Jan 23, 2020 #1

    namr82race

    namr82race

    namr82race

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    I have purchased a christavia frame and wings . It is the MK 1 I would like to put flaps on it . Has anyone built flaps on a MK1 I know the Mk 4 had them but that is a hole different plane. Also has anyone enlarged the rudder for better control on floats?
     
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  2. Jan 23, 2020 #2

    Pops

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    I have never seen a Christavia 1 with flaps. I have a set of plans. Always like that airplane. Friend of mine in WY finished his Christavia 1 in 1992 and been flying it every since. Loves it. Powered with a Cont- O-200, but the airport elevation is 7K. If you would like to contact him, send me a private email and I'll give you his phone # if he doesn't care. Great guy.
     
  3. Jan 23, 2020 #3

    namr82race

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  4. Jan 23, 2020 #4

    Victor Bravo

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    The traditional method of adding flaps to a wing is to just make all of the ribs as "aileron bay" ribs, and build four ailerons instead of two, and just make a flap control circuit for the inboards instead of an aileron circuit. Very rarely would this method be inappropriate. However, flap deflection changes and adds to the loads on other parts, so you have to figure those new loads into it.
     
  5. Jan 23, 2020 #5

    cluttonfred

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    It might be worth looking at the differences between an uncovered J-3 Cub wing and a PA-18 Super Cub wing to see how flaps were added and the wings beefed up as Piper developed the basic Cub over time.
     
  6. Jan 24, 2020 #6

    Dillpickle

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    Just thinking out loud...the stall speed is already pretty low, 40 if I recall correctly. A steeper approach can be had with a good slip. If you are trying to lower the stall speed even more, without the added complexity of flaps, have you considered Vortex Generators?
     
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  7. Jan 24, 2020 #7

    Pops

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    I agree, just build by the plans and build light, with the low stall speed flaps are not needed except for drag, then just slip for the extra drag, no additional building and lighter.
     
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  8. Jan 24, 2020 #8

    bmcj

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    I suspect the OP is looking for more lift and slower stall for float operation.
     
  9. Jan 24, 2020 #9

    namr82race

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    Yes I am looking for more lift. There was a guy on this site ten years ago that built one with flaps . He has not been on here for ten year so I dont know how to find him . I like the VG idea also , If I would ever sell the plane the first thing they will look at is does it have flaps. Got to compete with the Kitfox . LOL . I know they arent the same type of plane. With floats you need all the lift you can get out of it. Your ideas are all great. I had not even given the Idea of building it like the ailerons but that is a good idea also.
     
  10. Jan 24, 2020 #10

    Pops

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    With any engine heaver than the Cont 0-200 you will have W&B problems. I know some builders has put Lyc 235 in the Christavia 1 but they always have to put weight in the tail. If I built one for floats in would be with a non electric Cont 0-200 for the lighter weight possible. You can add the weight of the flaps and floats and an electrical system and not have as good flying airplane as making it non-electric light weight airplane. Like a J3 on floats with a non electric 0-200

    My friend in WY even had to put weight in the tail with a Cont-0-200 with an electrical system in his Christavia 1. It was designed for the weight of a Cont A-65 engine.
     
  11. Jan 24, 2020 #11

    namr82race

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    I think I am going to put the yamaha apex engine in it. 140 hp with the weight of a 170
    lbs
     
  12. Jan 24, 2020 #12

    cluttonfred

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    I don't know much about Yamaha snowmobile engine conversions for aircraft but that certainly would be plenty of power. Are there any smaller Yamaha conversions out there under 100 hp as an alternative to a VW?
     
  13. Jan 24, 2020 #13

    namr82race

    namr82race

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    There is the Yamaha Phazer engine very reliable but you are on your own on the conversion. There is a guy working on making a pru unit for it but it is a couple years out.
     
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  14. Jan 25, 2020 #14

    Dillpickle

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    As someone who has purchased and sold aircraft, I can honestly say l'd be more concerned about the fact that an aircraft (not designed or engineered for the stresses of flaps) had flaps added! Track down and read Bob Barrows interview in which he claims adding flaps to his LSA would add significant weight to do correctly. That is why his Patrol has Flaps, and the LSA does not. Both perform well. As far as needing the extra lift...Do you? Where are you flying that that will impact your safety? Have you observed the performance of the MK1 on floats and found it marginal? Since you HAVE the wings and fuse, I'd do this: Start stock, and put your $ into horsepower. Stay light--Hand propped well built C85 stroked and optimized. Add the Vg's, lots of articles on how, and you don't need to run a bunch of numbers to find success. Lots of low and slow guys have already done the work to optimize the placement on fabric wings. https://www.experimentalaircraft.info/flight-planning/aircraft-lift-augmentation-devices-1.php
    And if getting of the water in a really short time is important to you, build the Mk1, sell it and buy one of these: Wow. Just wow getting off the water in short distance, 2 or one up,,, turn the horrible music down.
     
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  15. Jan 25, 2020 #15

    dog

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    I also have a cristavia 2 place,and imediately began
    the same thought process,one look at the "alaska airframes"site and the double slotted flaps they are building will have your subconsious working overtime,all super slick billity goodness.
    I am eating beens and rice,cutting my own firewood, and patching my clothes,just so I can put
    some cash down when It will comes time to finish
    up my plane I can pay to play.
    The flaps are great,but they will cost,take time, and
    might have less effect than a tuned motor and keeping everything super light.
    Everybody says the same thing hand proped c-85/90 with the o-200 crank, wood prop pitched for climb.
    Its gona get off just fine.
    I have the a-65 and a metal prop,so am considering
    building a new motor and selling my motor and parts,prop other bits, eating lots more beens and
    getting the best power to weight motor that I can.
    I want those alaska airframe double slotted flaps,
    but my subconsious hasnt marched me in and remortgaged the house yet.
    I am taking pictures and will put up a build thread.
    And as someone once said "simplicate and add lightness"
     
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  16. Jan 25, 2020 #16

    namr82race

    namr82race

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    OK before this all gets way off the subject Ron Mason the man who built the MK 1 and engineered it Did make a flap drawing for the MK 1 but only on request . Now that Ron is no longer a part of the Christavia I am looking for someone who can hook me up with info on the flap build . I talked to Ron Mason in person 25 years ago about it and he said his biggest fear was a pilot getting a plane off the ground to quick and stalling it to close to the ground. He also went on to say that is the sole reason that he has the builders of the MK 4 to cut off the gear when building to lower the angle of attack so it wouldnt lift of to soon. It was a safety thing. I did buy plans from him then but never did the build, I have built a plane before and looking forward to finishing this project I bought . I have talked to the milman and rainbow people on the 7 GCBC flaps .
     
  17. Jan 25, 2020 #17

    dog

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    Ok then.
    The plans that came with my cristavia project are,
    very much the worse for wear.illegible in areas.

    I put an add on barnwampers looking for another set, and got a response very quickly,half the price of
    new and got em.

    So easy peasy,get you some free adds up.......................before I do.
     

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