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  1. #1
    GRandolph's Avatar
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    Fuselage Building Help Needed

    I am starting to build a Das Ugly Stik from plans which I have enlarged to 120%. A couple years ago I built the same plane at the original size of 54" wing span (tip rib to tip rib). The new build will have a span of 67" (tip to tip rib), which should be right sized for a 1.20 AX. My question is about what to use to build the fuselage. The original plans call for using 1/4" balsa sheet for the sides, top, and bottom of the fuse (typical box). But with the larger size, I am forced to purchase 6" wide sheets of 1/4" balsa. Does anyone know if using something else, like 1/8" lite ply, would be lighter and/or stronger than 1/4" balsa? 6" x 1/4" balsais expensive!
    "When lift plus thrust is greater than load plus drag, anything can fly."

  2. #2
    eddieC's Avatar
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    RE: Fuselage Building Help Needed

    I would think 1/8" would be fine. Just have some support underneath, every 3" or so. 

    Some of the ARFs are built so light, you could almost put you finger through the side if grabbing it to pick up. 
    I might not be very good, but I'm fun to watch!

  3. #3
    k12rc's Avatar
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    RE: Fuselage Building Help Needed

    Just finished jet mach. Ultra sport 106" fus two layers of 1/8 lite ply for you one
    Ne layer is plenty
    don\'\'\'\'\'\'\'\'\'\'\'\'\'\'cry\'\'\'\'\'\'\'\' till\'\'\'\'\'\'\'\'it hits

  4. #4

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    RE: Fuselage Building Help Needed

    Go to your friendly Home Depot or Lowe's and get some 1/8 inch door skin. Use it as is or double it. One 4 feet by 8 feet sheet will be about the same price as two 1/4" by 6" by 48" balsa sheets and will build a bunch of airplanes. Just remember: Smooth Side Out...

  5. #5
    sensei's Avatar
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    RE: Fuselage Building Help Needed

    I think I would take another lighter approach, 3/32" bass plywood from Aircraft Spruce & Specialty, 3/8" X 3/8" balsa longerons and an open bay design.

    Bob
    Fly It Like You Stole It!!!

  6. #6

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    RE: Fuselage Building Help Needed

    I wouldn't use doorskin for anything structural after trying it in an R/C boat. One slight twist and the boat's framing exploded into splinters

  7. #7

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    RE: Fuselage Building Help Needed

    Not arguing with you Hydro but my Giant Stinger with a G62 is going on three years with a door skin fuse (double layer); would guess over 150 flights of at least 15 minutes each. My previous Stinger with door skin fuse sides and top had over fifty hours of flight time before I dumb thumbed it... Have to brace anything properly to resist twisting but that doesn't have to add a lot of weight or money.

  8. #8

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    RE: Fuselage Building Help Needed

    No arguments from here either. I had a different result than you when I tried to use doorskin so I don't, just personnal choise. Give me birch ply, lite ply and balsa for planes, birch ply and spruce stick stock for boats and I'm happy

  9. #9
    sensei's Avatar
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    RE: Fuselage Building Help Needed

    ORIGINAL: GRandolph

    I am starting to build a Das Ugly Stik from plans which I have enlarged to 120%. A couple years ago I built the same plane at the original size of 54'' wing span (tip rib to tip rib). The new build will have a span of 67'' (tip to tip rib), which should be right sized for a 1.20 AX. My question is about what to use to build the fuselage. The original plans call for using 1/4'' balsa sheet for the sides, top, and bottom of the fuse (typical box). But with the larger size, I am forced to purchase 6'' wide sheets of 1/4'' balsa. Does anyone know if using something else, like 1/8'' lite ply, would be lighter and/or stronger than 1/4'' balsa? 6'' x 1/4'' balsais expensive!
    Just curious, what do you or any of you guys believe is fair flying weight for something this size? or does it even matter that much too you?

    Bob
    Fly It Like You Stole It!!!

  10. #10
    GRandolph's Avatar
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    RE: Fuselage Building Help Needed

    Thanks for everyones replies. Sensei, my original size 60 Stik I built two years ago weighed in at 8 lbs with engine - very heavy. So, that is why I am wanting to build lighter this time. I hope I can end up with a weight of 9 lbs on this larger plane. Mind you, the previous build used bass wood front and rear spars, dowel rod LE, 1/4" a/c plywood center rib (with tab inserting inside 1/4" a/c ply former!). This build I am leaving off the front spars all together (the 1/4" square sticks in front of the main spar), using a balsa LE, a balsa 1/4x1/4 rear spar, and hopefully will use dowel rods to hold the front of the wing instead of the interlocking tab made of 1/4 a/c ply. I also plan on using a bigger firewall, 3/8" a/c ply and will shorten the nose by at least 1" to help prevent from being nose-heavy.

    So, for the fuselage, it looks like I will try the 1/8" lite ply for sides. I will double this with another section of 1/8" lite ply from the firewall to the TE of the wing saddle. But, what about behind the wing saddle to the tail feathers? Can I use built up stick construction? I have never built one like this. What do I use? Balsa sticks or bass wood. And just as important, how do I glue the sticks to the front part of the fuselage where it uses the 1/8" lite ply?

    "When lift plus thrust is greater than load plus drag, anything can fly."

  11. #11
    sensei's Avatar
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    RE: Fuselage Building Help Needed

    If you use the 1/8" light ply for the entire fuse sides and 3/8" x 3/8" medium density balsa longerons you can skeleton the sides of the fuse leaving only 3/4" ply cross sections, cross grain balsa sheet the top and bottom with 1/8" light density and come up with an extremely rigid and light weight fuse. I have actually used this method on many of my giant scale build threads and it is a very efficient way to save weight while maintaining strength. On the firewall I would never use light ply, it is best to go ahead and use 1/4" birch plywood and be done with it. Glues, I build all my fuses with thin and medium CA. but that is just me...

    Bob
    Fly It Like You Stole It!!!

  12. #12
    GRandolph's Avatar
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    RE: Fuselage Building Help Needed

    I have never constructed a fuselage like this, Sensei. I am trying to understand what you mean. The 3/8x3/8 med balsa longerons would be glued to the inside of the fuselage sides starting at just behind the firewall and running the length of the 1/8" lite ply sides backwards. The 1/8" lite ply fuse sides would end at the TE of the wing saddle and only the longerons would continue back from this point all the way back to the tail feathers. When you mentioned the 3/4" ply cross sections you lost me. Surely you don't mean 3/4" thick ply used as formers inside the skeleton section?
    "When lift plus thrust is greater than load plus drag, anything can fly."

  13. #13
    sensei's Avatar
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    RE: Fuselage Building Help Needed

    Yes this is right. The 3/8x3/8 med balsa longerons would be glued to the inside of the fuselage sides starting at just behind the firewall and running the length of the 1/8" lite ply sides backwards. Here are a couple of pictures of the skeleton frame work that I do on my builds. What I am telling you is picture this framework with the 1/8" thick light ply bonded to it, then cut out leaving only a open frame 3/4" wide. Here is one more picture showing the balsa frame with light ply skins then the plywood all lightened up.

    Bob
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    Fly It Like You Stole It!!!

  14. #14
    GRandolph's Avatar
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    RE: Fuselage Building Help Needed

    I get it now! Thanks.
    "When lift plus thrust is greater than load plus drag, anything can fly."

  15. #15
    sensei's Avatar
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    RE: Fuselage Building Help Needed

    What did you say the span is going to be, and how many ribs are in the wing if you don't mind saying?

    Bob
    Fly It Like You Stole It!!!

  16. #16
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    RE: Fuselage Building Help Needed

    I have made my own ply with 3 layers of balsa.  You could do an outside layer lengthwise of 1/16, middle layer of 1/32 verticle, and inside layer lengthwise again with 1/16 to the end of the saddle and 1/32 back from there.

  17. #17
    GRandolph's Avatar
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    RE: Fuselage Building Help Needed

    Wing span will be 67" from tip-rib to tip-rib. Including the wing tips, the span will be 74". I was planning on spacing the ribs 3" apart for the web sheeting (3" balsa sheet), this would give me about 22 ribs. Below is a picture of the original sized stick I built a couple years ago. I originally installed a 91 four stroke on it but this was not enough power so I ended up with a 95 AX. Before I settled with the 95 AX though, I briefly had a 1.20 AX on the plane but this was too much So, now I want to try to build a Stik that will fit the 1.20 AX.

    Another modification I want to make on the next build is to cut big litening holes in the rudder. The previous stik used solid 1/4" balsa sheet for the fin and rudder. On the next build I will cut big sections out of the fin and rudder. The stab is sheeted.

    I also plan on installing bigger ailerons - the original design called for teeny tiny aileron strips as can be seen in the photo. The new stik I am building will have ailerons that are at least 2 and 1/2" inches wide. This is the biggest aileron stock that Balsa USA sells. Not sure if this will be big enough though.

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    "When lift plus thrust is greater than load plus drag, anything can fly."

  18. #18
    eddieC's Avatar
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    RE: Fuselage Building Help Needed

    What color is that? Nice!
    I might not be very good, but I'm fun to watch!

  19. #19
    GRandolph's Avatar
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    RE: Fuselage Building Help Needed

    It's neon green monokote. Looks great but is heavy and difficult to shrink.
    "When lift plus thrust is greater than load plus drag, anything can fly."

  20. #20
    sensei's Avatar
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    RE: Fuselage Building Help Needed

    In Monokote, red is the lightest to use, just saying. The reason I asked about the ribs earlier today is if you go with a 5 or 6" spacing you can loose nearly half the ribs, I did this very thing along with the fuse mods I spoke of on a friends dream Machine and wound up taking the airplane from a 5 1/2 lbs. to just under 3 lbs.

    Bob
    Fly It Like You Stole It!!!

  21. #21
    GRandolph's Avatar
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    RE: Fuselage Building Help Needed

    Hmmmm. I think at the least i could push the ribs to 4" apart and use 4" web sheets. That would cut down the # of ribs from 22 to 16. And, yes i am planning on using either red or transparent red monokote on this build. I heard that the transparent red and yellow are even lighter than regular monokote.
    "When lift plus thrust is greater than load plus drag, anything can fly."

  22. #22
    sensei's Avatar
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    RE: Fuselage Building Help Needed

    ORIGINAL: GRandolph

    Hmmmm. I think at the least i could push the ribs to 4'' apart and use 4'' web sheets. That would cut down the # of ribs from 22 to 16. And, yes i am planning on using either red or transparent red monokote on this build. I heard that the transparent red and yellow are even lighter than regular monokote.
    You are right about the transparent red and yellow my friend, now keep the landing gear as light as possible and there is a good chance that you will be able to use a smaller lighter engine further reducing the all up weight and getting the same or better performance from you airplane. This type of building mentality is something I have banked on for years now as demonstrated in all my build threads and flight videos. I think your going to have a real winner with this one and I wish you the very best. Here are a couple of my build threads and flight videos, maybe there is a couple of tricks you can use on down the road.

    Bob



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    Fly It Like You Stole It!!!

  23. #23
    GRandolph's Avatar
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    RE: Fuselage Building Help Needed

    Thanks for the link, Sensei. I am off to the LHS this morning to buy some of the wood so at least I can start cutting some ribs this weekend!
    "When lift plus thrust is greater than load plus drag, anything can fly."

  24. #24
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    RE: Fuselage Building Help Needed

    The GP Giant Big Stik ARF is an 80 inch model. http://www.greatplanes.com/airplanes/gpma1224.html
    It appears to be 1/8 lite ply construction with a few doublers around the wing area and forward to the firewall. One of our club members has one with a 1.60 two stroke. He is an aggressive flier and it has not broken.
    Lite ply is stronger than I would ever believe... until a crash. Then it seems to 'explode' into tiny bits
    - Carrell

  25. #25
    GRandolph's Avatar
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    RE: Fuselage Building Help Needed

    Yes, I have seen one of those at our club also. I think the pilot at our club has an OS 33 GT gas engine on his and it smokes! I would love to get a closer look at it. It looked to have lots of 1/8 lite ply construction with lightening holes everywhere. I wish I knew how wide the ailerons were as I wanted to make mine as big (proportionately that is since mine will be a 1.20 size with 67" wing span).
    "When lift plus thrust is greater than load plus drag, anything can fly."


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