Wednesday, February 13, 2013

Building the FliteTest NutBall Swappable

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By Gabriel Staples
Written: 13 Feb 2013
Updated: 25 June 2013

THIS DOCUMENT IS INCOMPLETE, BUT HAS MANY GOOD LINKS, PICTURES, AND RESOURCES BELOW.  IT WILL BE FINISHED IF PEOPLE BEGIN REQUESTING THAT I FINISH IT, OR IF THERE ARE MANY QUESTIONS ABOUT IT, WHICH YOU CAN PUT IN THE COMMENTS SECTION BELOW THIS POST.  

--Since FliteTest has already done so much to support the build of this aircraft, it is likely that the links and pictures I already have below will suffice.  Be sure to check out my Center of Gravity section below, however, as it pertains specifically to the 24" diameter NutBall, which FliteTest does not build.  As you will see in their links below, they prefer to build their 19 1/3" version of the NutBall.

If you have any questions or comments while reading this, or any other article, please post it in the comments section below the article. Thanks!

Related Articles:
So, one of my friends I just helped get into RC was looking at my article above ("Buying Parts for the FliteTest Nutball Swappable - All at Once") the other day, and he asked me if I could post some dimensions, pictures, etc., and a few notes about how I built the airplane.  So, that's why I'm writing this post.

1st: Watch the Build Videos and Read the Flite Test Articles:
-Even watching the non-NutBall Build Videos will give you valuable building tips.  At a bare minimum, watch the Power Pod and NutBall build videos, as they both give you tips and tricks necessary to successfully build the NutBall:

  1. Power Pod Build:  http://flitetest.com/articles/ft-swappable-power-pod-kit
  2. Power Pod Electronics install:  http://flitetest.com/articles/ft-swappable-connecting-electronics 
  3. NutBall: http://flitetest.com/articles/nutball_scratch_build 
    1. The new FliteTest NutBall build video
    2. The original FliteTest NutBall build video (I like this build video better)
  4. Delta:  http://flitetest.com/articles/DeltaScratchBuild
  5. FT Flyer:  http://flitetest.com/articles/ft_flyer
  6. You may also check out this article here, titled, "Swappable Nutball and Hots Dart"

2nd: Download & Assemble the Plans
-Download them, then print them, cut off the edges of the paper as necessary, and tape them all together to make full-size plans:
-I noticed that FliteTest has updated some of their plans in the articles above, so feel free to use those.  However, if you want the exact ones I have used to successfully make several NutBalls now, here they are:

All plans are available here.  To download them, click on the file you want, then go to File --> Download.
A brief description of the files is below.
(Note: I originally got the NutBall plans from page 2 of this RCGroups build thread.  The NutBall was originally made by "GoldGuy," if I'm not mistaken.  Then, FliteTest simply came along and made a swappable fuselage for it, and made it into one of their most popular planes in their "swappable series.")
  1. NutBall_full 17''.pdf - these are the 17 inch diameter plans.  I don't use these, but here they are in case you want them; I prefer the 24" diameter NutBall.  This is a one-page view.
  2. NutBall_tiled 17''.pdf - these are the 17 inch diameter plans, tiled so that you can print them out on a regular printer, cut off the excess paper, and tape them all together to get full-size plans.
  3. NutBall_24_tiled - build this one!!! (will require 2 sheets of 20'' x 30'' Dollar Tree Foam).pdf - these are the NutBall plans I use. They work great.  I prefer the 24" NutBall over the 17" of 19" NutBall, by the way, because it is still very easy to use Dollar Tree foamboard, and it has waaaay more wing area than the 17" or 19" versions, so it will have a much lower wing loading and hence be able to fly much more slowly.  It will have more of a "floaty" feel to it (which is good), than the other two versions, assuming all other things are equal.  
    -For your information, the 17", 19", and 24" diameter versions of the NutBall have wing areas of 908 in^2, 1134 in^2, and 1810 in^2, respectively.  That means that the 24" diameter NutBall has 99% more wing area than the 17" NutBall and 60% more wing area than the 19" diameter NutBall.  Again, this means it can carry much more weight and/or fly much more slowly.  
  4. swappable fuse & Delta fins (print ''poster'', 100%, w-Cut Marks, Labels, & 0.5in overlap).pdf - this file contains the swappable fuselage plans I used for my NutBall and Delta wing.  It also contains the Delta wing fins if you want them for building the swappable Delta wing plane.  Using Adobe Reader X, print as the instructions say in the file name (ie: poster, 100%.....etc).  The fuselage, firewall, and delta fins are to scale, but the landing gear is not.  It's shape is correct, but not its size.
  5. swappable delta (print ''poster'', 100%, w-Cut Marks, Labels, & 0.5in overlap).pdf - Delta plans.  here they are if you want them.

3rd: Buy the Airplane Parts:
Estimated cost of airplane only, with *no* electronics: $5~$15.
Estimated cost of optional colored packing tape (for decorating): $5~$45, depending on how many colors you buy.
Estimated cost of building supplies: $25~$40.
  1. Airframe:
    1. two $1 sheets of 20"x30" foamboard from the Dollar Tree (note: this is ADAMS brand foamboard).
    2. 1/8" plywood sheet (maybe 8"x10") from the Hobby Lobby balsa sheet rack in the back of the store ($1.79 last I checked I believe)
    3. $1~$2 pack of 100 shish-ka-bob (bamboo) skewers from Walmart (in the BBQ section of the Garden Center) or wherever
    4. Jumbo popsickle (craft) sticks at Walmart - pack of like 100 for a couple bucks - to be used to make the 2 control horns
    5. (music wire)
  2. Landing Gear (optional; note: plane is easier for a beginner to land *without* landing gear, since you can just safely belly land it *anywhere* in a large grass field, without having to worry about needing a smooth surface or accidentally flipping it over due to the wheels catching):
    1. (wheels)
    2. (Wheel Collars)
    3. (Music Wire)
  3. Building Supplies:
    1. Tape:
      1. Packing Tape:
        1. $1 roll of cheapo clear packing tape from the Dollar Tree
      2. Fiberglass-stranded Tape (mandatory item, use as the build video shows):
        1. Scotch Strapping Tape (small roll): OR
        2. Duck brand Strapping Tape: OR
        3. Scotch Extreme Packing Tape:




    2. Hot Glue Gun:
    3. X-Acto knife, box-cutter knife, razor-blade knife, or equivalent, $0.50~$8 (note to self: add link to X-blade knife & blades on HK)
    4. Precision Screwdriver set: --add link to the Husky set I have, as well as the decent Harbor Freight set.


4th: Build the Plane!
Estimated build time (this does not include electronics installation):  4.5~5.5 hrs. for the experienced builder, including electronics installation; 6~10 hrs. for the novice builder.
Tips:

  • The Jumbo Popsicle Sticks are used to make control horns.  Click here for the file, then go to File --> Print.  Make sure to print the file Actual Size, NOT Shrinking it or Fitting it to a Page.
  • 1.94" high parts box, for wingtip polyhedral......follow build video

















5th: Buy the Electronics
...


6th: Install the Electronics & Balance the Propeller
...



7th: Center of Gravity (C.G.), Maiden Flight, and Trimming
After much flight testing and probably hundreds of flights, here's my Center of Gravity recommendations for the 24" diameter NutBall:
Ideal CG: 5.5"~6.0" back from the leading edge of the wing, measured right along the wing root (ie: down the centerline).  The CG on this plane, however, can be about as far forward as you want (I didn't go farther forward than ~5.0"), and as far back as 6.5".  With a CG of 6.5" the plane can be very fun to fly and with large control throws does back flips (EXTREMELY tight, approx. 3 ft. diameter loops), and flat spins very well.  However, inverted flight is horrible with the CG at 6.5" back, as the plane is somewhat unstable and hence trims out with some down-elevator.  For nice inverted flight, 5.5~6.0" back works nicely.




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