Friday, March 1, 2013

Getting into Scratch Building - 20+ Planes with ONE Motor & ONE Power Pod!

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Getting into Scratch Building - 20+ Planes with ONE Motor & ONE Power Pod!

By:  Gabriel Staples
Written: 1 March 2013
Last Updated: 21 Feb. 2015
-added "Reinforcement" section below - 20 Feb. 2015
-added the entire "Which Foam to Buy" section, incl notes on Dollar Tree foamboard & depron - 8 Feb. 2015
-added a link to my new free-flight Stingray glider I mention below - 16 July 2013

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, over a year ago now I discovered the Flite Test NutBall and Delta Wing (both wings, separated from the power pod, are shown in the picture above and to the right).  These planes are unique in that FliteTest came up with the ingenious idea to use a single motor, speed controller, and receiver combination in order to power multiple airplanes!  This is a fantastic solution, as it allows someone to get into this hobby VERY economically, and all of the planes are built using Dollar Tree foamboard (ADAMS Readi-board), shish kabob (bamboo) skewers, hot glue, popsicle sticks, and packing tape!

As of today, I have built and flown both the NutBall and the Delta Wing, and love them both.  I have even prototyped and tested, for my local Boy Scout troop working on the Aviation merit badge, a $5 free-flight glider based on the NutBall, which is capable of being bungee-launched (via a home-made $25~$35 launcher) to altitudes up to 250 feet, and flying several hundred yards distance in a single flight!  My wife named it the Stingray (see photo of a stingray to the right), since the glider resembles a stingray flying backwards.  I would like to post the plans and video of the Stingray glider and bungee launcher when I get the chance, so other Boy Scout troops and do-it-yourselfers can make one too (for a sneak peak of the glider, see my new post here).  As for the FliteTest airplanes I've built, the NutBall is especially a blast to fly for an advanced pilot, yet can be gentle
enough (with limited control surface throws [movement]) to be a great beginner airplane--though the Bixler and Hawk Sky are still much better!  I have also designed and tested what I call a "training fin" for the NutBall, which can easily be velcroed onto the top of the plane in order to make it self-right (roll level automatically) whenever it is banked.  This is really useful for a beginner as well.  (More to come on this; I need to write a post on it still too).

Well, after knowing about only a couple FliteTest "swappable" series airplanes, on 1 March 2013, I discovered sooooooo much more! I can't believe I've been so out of the loop on what FliteTest has been up to!  For those of you unaware, they are now making absolutely fantastic-flying airplanes, using the SAME NutBall swappable power pod design, with full airfoils and very good looks.  Here's the list I've just compiled from them.  If you haven't seen all of these already, it's definitely worth your time to check them out!


  • First off, the swappable FT (Flite Test) Power Pod (pictured above), which is the core of all of these designs:
    • Here is the parts list that FliteTest recommends.  It is a relatively low-power setup, optimized for the beginner, with good low-speed thrust and not too high top speed.  
    • Here is the parts list that I recommend. It is a relatively high-power setup, optimized for the beginner to advanced pilot and everything in between, with the option of higher thrust and higher speed if you want it (by using a 3S LiPo vs. 2S LiPo).  For a more gentle, beginner type feel, use the slow fly (SF) 8x3.8 props and the 2S LiPo batteries.  You might even try the 7x5E prop with the 2S batteries, for more gentle flight.  For higher-speed flight with the 2S batteries use an SF 9x6 prop.  For a much more powerful system with a good mix of thrust and speed, use the power system in my recommended parts list above, with the 3S 1300mAh LiPo battery and APC-style 7x5E* prop.  With this setup, the 24" NutBall version I prefer is capable of accelerating vertically, even using a battery as large as a 3S 2200mAh LiPo (though it can just barely accelerate vertically with the extra weight of this battery).  *Caution: do NOT use props larger than the APC-style 7x5E, with a 3S battery, on the recommended motor in my list, as it will pull too much current and burn up the motor.  Also, do not run full throttle for long periods of time (longer than ~30 seconds) with a 3S LiPo and 7x5E prop, for the same reason.
  • Here are the Master Links for all of FliteTest's amazing work in their swappable series airplanes (these links were obtained from the Power Pod link above)!
  • Some of their "Swappable"-series planes, which use the power pod design above, which REALLY IMPRESS ME, include the following:

So, now that I have discovered a whole host of other airplanes by Flite Test which can use my one, single, economical, swappable power pod, and that have fully-formed 3D airfoils and are very nice looking airplanes, I certainly am going to begin building these things and expanding my collection of RC airplanes to fly, and I highly recommend you do too!

Other Scratch Builds to look at or do:
So, clearly I favor the FliteTest scratch built airplanes above with the swappable power pod, but hundreds of other scratch built airplanes and plans are available online as well.  With a little imagination, and some building ingenuity, you could easily make many, if not all, of these other scratch-build airplanes use your Flite Test swappable Power Pod too!
  • EA (Experimental Airlines) SYNAPSE Foamboard Flying Wing - this is another airplane built from Dollar Tree foamboard.  This plane looks like an incredible FPV ("First Person View" -- using a camera and video screen to fly your plane as if you were inside of it) flying platform.  With the right setup, I think this plane could be made to fly over 1 hr. at a cruising speed of 35mph or so.  With the right equipment, I think you could easily do flights 10 miles there and back using high quality FPV gear and amateur UAV (Unmanned Aerial Vehicle) fail-safes such as "Return to Home."  Anyway, even as a standard RC airplane, this plane really looks like a LOT of fun!
  • RCPowers (http://rcpowers.com/)

    • FREE RCPowers F-35 EasyBuild V2 (he normally charges ~$13 for plans like this).  Using 6 HXT900 9g servos (from USA warehouse/from International warehouse) on this plane and a nice computer radio could make this plane VERY interesting and fun to set up and fly!  You would use 1 servo for each aileron, 1 servo for each rudder, and 1 servo for each side of the elevator, then special computer radio mixes would make the plane very versatile and maneuverable.
    • FREE RCPowers Extra 300S --> click File --> Download to save the files.  Search on YouTube for "rcpowers extra 300" to find dozens of videos, including 3rd-party build videos.
  • Flying Sidewinder Missile, from RCGroups.com -- download the PDF plans in the 1st post
  • www.parkjets.com - click "Free Plans" at the top of the screen in order to search through their 100's of user-provided, FREE PDF plans! - again, after building a couple of the Flite Test "swappable" airplanes above, using your ingenuity you could easily adapt many of these planes to use your same swappable power pod!

Which foam to buy?
  1. Dollar Tree foamboard (AKA Adams Readi-board): FliteTest makes all of their planes with Dollar Tree foamboard. It has a little white sticker on it that I believe says "Adams Readi-Board" (I don't have a sheet in-hand to double-check it). Here is a link to it online.  It is a 3/16" thick, relatively low-density extruded polystyrene foam core with paper on each side. Each sheet is 20"x30" and costs only $1. The white foamboard seems to me to be stronger than black. This is the case with many other types of foam too.
    1. Notes about quality, strength, and weight: If you want to build with foamboard, I recommend you do NOT use foamboard from ANY other store---unless you want it to weigh as much as thin plywood. The reason that the Dollar Tree brand is specifically the *only* good airplane foamboard (ie: craft foam with paper on it) that I know of in existence is because they special order their own low-density blend of it in bulk directly from the manufacturer. Since they are a $1 store, their blend of the foamboard is lower density than all other foamboards (and also has a lighter and thinner paper covering on it), and therefore it is considered "cheaper" and "lower quality" for school projects and crafts and things. For RC airplanes, however, the low-density, cheap Dollar Tree foamboard is FAR BETTER, since it is so light. Again, if you go to Target or Staples or Walmart or something, and build a plane out of their foamboard it may be much stronger but it will also feel like you just taped a bunch of rocks to your plane.  For very high-speed or very large planes you want to make out of foamboard, though, the extra strength of other, more expensive foamboards *may* be desirable and worth the extra weight. 
    2. Strength & Waterproofing:
      (Source)
      For most building applications, with some exceptions (ex: the inner sides of folds on an Armin wing), do *not* peel the paper off of the Dollar Tree foamboard. The paper adds the bulk of the strength to the foamboard. Without it, the foam becomes weak. However, in high-humidity environments (ex: Ohio, Georgia, South Carolina, etc), expecially in the Summer, or in rain anywhere, the paper will get damaged and your plane could fall apart. To prevent this, put several (2 to 3) LIGHT coats of polyurethane on the plane, giving adequate time to dry between coats. Polyurethane is oil-based, so light coats will not damage the foamboard. However, if you use heavy coats, the paper will get saturated and mushy, and the hot-glue joints you have will become soft and loose. Ie: soaking your airplane in polyurethane is a BAD idea and will destroy the plane.
      1. Polyurethane example: 1-qt. Semi-Gloss Fast-Drying Polyurethane, ~$11 at Home Depot
      2. Here is a FliteTest article on the topic: "Minwax on Your Plane"
    3. Reinforcement: You can strengthen the foamboard with packing tape, strapping tape (has fiberglass strands in it), bamboo skewers (shish kabob skewers) from the grocery store, and carbon fiber rods. I usually just use the first three, as carbon fiber adds quite a bit more cost. Without electronics, an entire airplane built from Dollar Tree foamboard can cost me as little as $5 or so--and these aren't weak little planes, some of my Dollar Tree foamboard planes fly 70mph or more, and could go faster if they had bigger power plants!
  2. Depron. Depron is a high-quality and very strong extruded polystyrene foam which does *not* have any paper on it.  Being made strong without having paper on it is a good thing because it means that glue bonds will be stronger (since you don't have the possibility of just gluing to the paper, which could peel off under load), and since it does not require any special waterproofing.  It is far stronger and more durable than Dollar Tree foamboard, but also much more expensive. It costs ~$10/sheet for a 6mm [~1/4"] thick x 27.5" x 39" sheet and can be purchased at many local hobby shops or online. It is the foam of choice used by many scratch-builders.
    1. My favorite place to purchase it online is Grayson Hobby
      1. Grayson Hobby depron foam available
      2. I prefer the 6mm 1/4 Case White Depron 27.5" x 39" - 5 sheets, for ~$40 + shipping.
  3. Dollar Tree foamboard & Depron notes:
    1. Both are made of extruded polystyrene (a high-density version of the same material Styrofoam is made of), so both are easily glued with hot glue.
    2. However, both foams will also be dissolved by the solvents in spray paints and standard superglues (ie: CA adhesive). Test a scratch piece of the foam before you start gluing or spraying anything on your foam airplane. 

PLEASE LEAVE QUESTIONS OR COMMENTS BELOW.

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Questions and Answers:

Q: Does a swappable with only elevon control (FT Delta) require a special transmitter that mixes the elevator & aileron inputs?
A: Yes, a special mixing capability is required that mixes the elevator and aileron inputs, but no it does not always have to be a special transmitter. Let me explain: usually a special transmitter is used, with built-in mixing capabilities, such as a computerized one like this or this, or a non-computerized one that has a built-in mixing function switch like this one. However, the cool thing about today's fancy electronics is that even with a standard radio with NO built-in mixing functions, you can use an *external* mixer like this or this. The built-in mixers will always be a little bit smoother, but the external mixers are super economical and work just fine for someone with a basic radio.



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8 comments:

  1. Does a swappable with only elevon control (FT Delta) require a special transmitter that mixes the elevator & aileron inputs?

    ReplyDelete
    Replies
    1. Yes....sort of. Check out the bottom of the article to see my response.

      Delete
  2. Do you see any insurmountable reason why a scratch-build plane couldn't be designed to use the power pod reversed, in pusher-prop mode? That might be an interesting mod to the Parkjets.com Cutlass model.

    ReplyDelete
    Replies
    1. also...you'll need to put a foam plate or something over the "back" of the power pod (which is now the front), to make it more aerodynamic when mounting it backwards in pusher configuration. Lastly, I recommend some cooling holes (for air to enter one end of the power pod and exit the other end) if you have the ESC mounted inside the power pod. ESC's require moving airflow to keep them cool...even if using a much larger ESC than required. I know that the 10A Castle Creations ESC, for example, says right on the package that its rating of 10 amps was "determined with a 5mph airflow over the ESC."

      Delete
  3. Nope, definitely no reason why you can't do that. Just leave the landing gear off, swap any two of the three wires from the ESC to the motor, in order to change the motor's direction, and mount the propeller on the motor the other way around, and you should be good to go!

    ReplyDelete
  4. The fowl flyer from Flite Test uses the pod in a pusher configuration.

    ReplyDelete
  5. This is an excellent idea for people who are interested in getting in the RC Plane hobby. However, after a while, you will definitely want more adrenaline and these models don't offer the amount of it as the traditional built RC Planes do. Furthermore, the entire process of building an RC plane from scratch is the most interesting part of this hobby. So, if you are interested in building a more complexed traditional RC plane, here is what you need to know http://mydronelab.com/blog/how-to-make-an-rc-plane.html

    ReplyDelete

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P.S. Yo hablo español también. Je parle français aussi. (I speak Spanish & French too).