FT Explorer ... Depron style.

Discussion in 'Scratchbuilding!' started by TomMonton, Feb 21, 2016.

  1. TomMonton

    TomMonton Administrator

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    Then I'll make you one Dan. .. this can be packaged a lot easier than a completely assembled bird. With the exception of the elevator/rudder section it breaks all down into 3 pieces.
     
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  2. See if you can sand the piece by marking how much its going in because thats what I did after attaching pieces of 3mm depron
     
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  3. Tom, you think I should go down about 1mm or 1.5mm all sides?
     
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  4. TomMonton

    TomMonton Administrator

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    Let me slice out a mock up and I'll report back.

    (Update)
    I'm seeing 46x33 maybe 32 mm as a comfortable fit. There should be enough room that you can still tape over the foam if you wanted to keep it detachable.

    I have depron due to arrive today finally and I'll let you know the finish result once I get it to work.
     
    Last edited: Feb 22, 2016
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  5. pileit1

    pileit1 Ace Pilot

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    How did the wing folding go?
     
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  6. TomMonton

    TomMonton Administrator

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    I haven't gotten there yet
     
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  7. Ok,
    Seems like you got the exact measurements from my original dimensions that I had modified. I guess then I'll keep my original file as I think the build errors in mine were due to the variation in the thickness of my MPF foam.
    The original dimension of the boom is 45.92mm x 32.2mm
     
  8. For the wing folding, here is my recommendation:

    1) Join the 2 wing pieces. Where you have the 50% score cut in middle, put some tape on other side that will stick nicely (I used strapping tape - good alternate is duct tape). The tape shouldn't come off when folding the wing or you can cause it to bend in some other place, crack it, misalign it, etc:

    IMG_0323.JPG

    2) Fold over the foam and make a deep bevel cut on BOTHsides(~30degrees) - this is more than what we are used to doing for our control surfaces:

    FullSizeRender 2.jpg

    3) Use a 3-4mm CF rod or similar size dowel/drill bit (use flat end) and crease the lines of fold:

    IMG_0327.JPG

    4) Now, glue the foam box spar along with wooden OR CF rod in place **not shown in picture**. Slowly fold over the top side of wing over with a rocking motion and not in one attempt (this could snap the wing at bevel cut - no worries if you do so). Since the wing span is big, I usually use a big ruler which helps in applying even pressure end to end:

    FullSizeRender.jpg

    5)Once you have folded over the wing to dry fit it nicely, go ahead and apply some foam tac in the beveled groove, the trailing edge spar (the outer edge gets most glue as this is where the pieces join) and fold over the wing all the way -> hold for 15sec -> release -> fold again for 10sec -> release and let it sit for a min or two (quickly proceed to next step)

    6) Apply some hot glue on top of the box spar - you could choose to use foam tac here as well but since I made my spar out of DTF foam (highly recommend!), I used hot glue... Go ahead and fold over the wing using the big ruler -> first apply pressure on wing where it touches the spar (this will make sure the curve/airfoil shape is right)... Now go ahead and put some pressure on the trailing edge to ensure pieces join well...

    7) Finally, remove the strapping tape (make sure the leading edge is holding up nicely) and go ahead and raise one side of the wing gently and release. Put some 5min epoxy in the gap to fill-in and raise the side again, this time using the "angle guide template" underneath and let it cure. You should now have a very nice wing built up!

    IMG_0254.jpg

    IMG_0255.jpg
     
    Last edited: Feb 22, 2016
  9. pileit1

    pileit1 Ace Pilot

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    Thanks malukk. I was mainly interested in how you did the leading edge. So I see you basically have two wing plates, top and bottom, joined with tape for the folding and gluing, then removing the tape afterwards or leaving it on for more strength and ding protection. Do you end up with a flat bottom airfoil like with DTF or more of a semi-symetrical airfoil? Also, using a FT style box spar, do you think an additional wood or CF spar is necessary? I built a Storch and have a Bushwacker ready for maiden. Those wings are super easy and fast to make and are quite strong, but that's with the paper skins which are absent here. I actually am considering doing the Bushwacker in MPF at some point if it flies well.
     
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  10. 1) I usually don't separate the top and the bottom pieces to begin with but do this instead:

    50% score cut -> fold over (the foam is still intact, doesn't break) -> make bevel cuts -> separate the top and bottom pieces NOW -> join them again with foam tac as you would for making a "glue hinge" making sure top surface of both is flush all the way -> tape on the other side -> follow steps as above...

    2) I do remove the tape as it doesn't look nice, adds weight and overtime it comes off! I do the brown paper/minwax(water-based) treatment on this instead, to provide a lot of strength - it stiffens up the foam significantly and also protects it from dings! Look at the picture (assembled plane) on page 1 which shows brown paper in the center of the wing - only did that so the rubber bands don't ding the foam. You could do the same treatment for entire wing which will make it super strong (better than DTF) while still keeping it light weight!

    3) The airfoil comes out the similar way as the DTF would or better. Thats why I apply pressure on top of the wing where it would touch the spar first! A little trick is to put a ruler on the bottom wing about 1cm from the grooved area and then fold the top piece! This way the bottom piece doesnt bend to give a symmetrical airfoil... See the pictures below:

    FullSizeRender.jpg

    FullSizeRender 2.jpg

    4) FT wings use double sheeted/laminated foam OR box spars. I only make the CENTER SECTION SPAR a little different: I use single sheet of foam (DTF) and laminate it with lowes/walmart/homedepot wooden ruler (cut it to about ~15")... The side spars remain the same way with just the foam. Also, I only use DTF for making spars! This way I save a lot weight while making the construction rigid overall as well as reinforcing the center section which is where there is a lot of stress...

    FullSizeRender4.jpg
     
  11. TomMonton

    TomMonton Administrator

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    Okay I think I'm back on track now. A fresh box of Depron come to the door today so I can get right back to work.

    I did rebuild a new boom with the new dimensions and things fit together nicely this time. Right now I'm letting CA setup on cf strips while I watch the game.

    uploadfromtaptalk1456188859551.jpg
     
    Last edited: Feb 22, 2016
  12. JettaManDan

    JettaManDan Administrator

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    ha! thanks but no! I still have not built 3 planes..and the Drifter....no room....time to junk out some planes again I think :(
     
  13. bimoadiprakoso

    bimoadiprakoso Top Gun

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    Decommissioning time!

    Sent from my LG-F320K using Tapatalk
     
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  14. jimpalmer

    jimpalmer Ace Pilot

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    I do my decommissioning quite often by high speed returns to earth. Always have a supply of spare parts.
     
  15. bimoadiprakoso

    bimoadiprakoso Top Gun

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    One fun thing to try Dan on decommissioning a plane: check the max throttle end point, set it to 120%.

    So, when doing nose dive, hit the throttle at max so it may have 120% punch. And BAM! It will hit the ground at higher than full speed

    Tried that crazy thing once. No electronics survived. that was a really good crash.

    Sent from my LG-F320K using Tapatalk
     
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  16. If you don't want them anymore, make a show of it and then salvage the parts. Hmmm, soda, Alka-Seltzer, pop bottle, launch quickly, oh and have the camera rolling. :D
     
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  17. JettaManDan

    JettaManDan Administrator

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    all good suggestions! lol - I just need one of you guys to make the trip down to me and point out planes you want...I've give a lot of them away ;) lol
     
  18. TomMonton

    TomMonton Administrator

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    This is my question. Would there be any advantage to adding flaps to the wing ? There is plenty of aileron here to work with yet.

    ....or things work just fine with a flaperon mix instead. Get over it and move on.



    uploadfromtaptalk1456258225153.jpg
     
  19. I am going with flaperon setting for now and if needed I'll go with flaps later on...
    I am keeping mine as light weight as possible as it will get the fpv equipment - maybe with a 2d servo gimbal on as well...
    This will slow down nicely as is so decided to go this way!
     
  20. TomMonton

    TomMonton Administrator

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    The motor pod. I really like this idea. .. a removable motor pod. I just need to think up a clever pin or latch mechanism to hold it in there.
    uploadfromtaptalk1456274868703.jpg [​IMG]

    uploadfromtaptalk1456274826440.jpg
    uploadfromtaptalk1456274816266.jpg
     

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