Spinster, the foamboard beginner DLG

by FAI-F1D | April 27, 2017 | (0) Posted in Projects

The new Spinster DLG is a super low-tech DLG that will cost about $30 to build and serves as an excellent introduction to DLG/F3K. It only takes a couple of evenings to build and has a removable wing so you can easily transport it to the flying field! Do you need more convincing? Take a look at the flight video!

The second flying session with this model produced the altitude plots below showing very above average launch heights for such a simple model; I was actually holding back on these flights because the first throwing blade I used was too weak.

The parts list below will cost you more than $30 because plywood and the like are not usually available in such minimal quantities. No doubt you will use those materials on future builds, however, so I have not counted them in the cost.

You will need the following materials to build this model:

  1. 2 sheets of Adams foam board
  2. 1 sheet of 3/32″x3″x36″ balsa, preferably C-grain
  3. 1 carbon fiber arrow shaft or Goodwinds.com boom, at least 32″ long (NOT a pultruded boom–those are too heavy).
  4. 4 micro servos; the Hextronic/Towerpro 9 g analog servos are more than sufficient. Search Ebay for “9g servo” to find the current lowest prices.
  5. 1 4+ channel micro receiver. Banggood has reliable dsm2 receivers for $6.
  6. 1 round cell Lipo battery (Turnigy 1000 mah is excellent).
  7. 1 Jst connector for the battery.
  8. Up to 3 servo extension wires (battery and aileron servos, depending upon length of wires–I only needed a battery extension).
  9. 1 small piece of 1/4″ balsa sheet.
  10. 1 piece of 1/64″ plywood (5″x5″ is sufficient).
  11. 1 piece of 1/32″ plywood (2″x2″ is sufficient).
  12. 1 piece of 1/16″ plywood (3″x10″ is sufficient).
  13. 1 .070″x.437″x23″ Carbon Rectangle strip from CST.
  14. 1 .016″x.118″ Carbon Rectangle strip from CST (at least 5″ long)
  15. 30 lb test spiderwire braided fishing line.
  16. 1 36″ length of .039 piano wire.
  17. 1 small block of blue foam or similar (at least 2″ cube).
  18. 1 sheet of computer paper.
  19. Masking tape, packing tape (or Blenderm), CA glue, and hot glue.
  20. 10” length of .010 piano wire (up to .015 will work, but could gradually wear down the tail surfaces)

While it is possible to fly this model with a 4 channel radio, you will need to fly with a forward CG and use a y connector to slave the ailerons, which will eliminate the flapperon function. DLGs are very mode-sensitive (I use 1/8″ flapperon droop in glide and 45 degrees droop for landing). I recommend at minimum a Spektrum DX6i or equivalent (Flysky i6 may be sufficient with a micro receiver).

Plans are located here: https://drive.google.com/drive/folders/0B9t_4cR6_fI7QjhEdlNYOW1qd3M?usp=sharing

This is not a forgiving build, but it is not terribly difficult. As such I have created a complete build guide for this aircraft, and I recommend you read it in its entirety before you even think about getting together the materials to build this model because there simply is not enough space here to fully detail this build on Flite Tests' domain. 

The complete builder's guide is located here:https://drive.google.com/open?id=0B9t_4cR6_fI7OWpnQ1czLWZWdWs

For best results, you should begin by watching Nerdnic’s speed wing build video, which is somewhat similar to the building methods used for this model’s wing. The figure below shows the layout of the plans. The long dotted lines represent score lines for cutting into the paper for beveling the wing. The short dotted lines represent the hinge lines for control surfaces.

Next we have the basic layout of the finished aircraft.

This is what your finished Spinster will look like:

At the heart of this model is a wing based off two years of efforts by Flyboa (member here and on rcgroups). The entire interior of the wing is de-papered before it is finally closed. Here is a wing ready for its foam spar to be installed. A 5" long carbon stub spar in the wing root will join the two panels in a way that prevents failure of the center join under the extreme launch loads.

Next we see the spars installed and the rest of the paper removed. Glue will be applied to all of the mating surfaces before the wings are closed in a single step (work fast!). Note that the wingtips are rounded off and the spars tapered at the tips for a clean, durable join.

The wing is now folded over to form a semi-symmetrical airfoil. With some finesse, slight washout can be introduced to the wingtips to further soften the low speed flight characteristics.

Next we cut the flapperons from the bottom and make sure that their faces are sealed with hot glue to improve torsional rigidity of the wing.

You want at least 45 degrees down travel in the flapperons for landing mode. This feature allows you to dive the model in from downwind and hit the brakes at the last second to catch it. It is preferable to never let the model land on the ground if

possible.

Join the wings together with a strong hot glued joint after installing the stub spar into the foam spar on one of the wings and slotting the other wing to receive it. You want to pump as much glue into the slot as possible. I'm serious - this joint gets really loaded down on launch.

The servos are installed in pockets in the wing just behind the spar. Their pockets are hogged out to leave only 1/16" of the servo's thickness sticking out, and then they are sealed to the wing's lower surface with hot glue for maximum strength.

A plywood saddle is mounted to the wing center with plenty of hot glue. This is the mounting surface for the removable wing. Except for the throwing blade, this is the last join you will make with hot glue. Get out a bottle of CA for the rest of the build!

Your fuselage is made from a 1/4" carbon fiber tube 32" long mounted to a heavy carbon strip which serves as the electronics mounting plate. A matching plywood plate is mounted to the top of the fuselage (fuse shown inverted).

Each servo includes two mounting screws you won't be using to mount the servos. Instead you'll use them to mount the wing.

Fabricate aileron pushrods from .039" piano wire. The control horns are cut from 1/32" plywood and are bonded all the way through to the top surface to prevent delamination

Get some 3/32" balsa sheet and cut out your tail surfaces. Cut and bevel the hinge lines which are then hinged with blenderm or packing tape.

You won't be using rigid connections to the tail surfaces. The tails are sprung and moved using tension strings. Here's the rudder spring being pressed into the rudder and vertical stab:

The stab uses two such springs and is mounted on an easy to make pylon.

Once you mount the stab, you'll drill a hole into it and thread the spiderwire pull string through to the front.

Install your tail servos by wrapping them with tape and gluing them down with ca glue. Notice the teflon tubes used to prevent chaffing of the pull springs and the 1s 1000 mah lipo taped the the front of the fuselage.

Tension the strings so that the tail surfaces are neutral and tie them off on the servo control horns (better yet, use the servo horn screws to hold the strings in tension so that they can be adjusted). Notice that the vertical stab is on the left side of the boom and the control horn is on the right side. For a right handed throw, this configuration is absolutely vital. Your model will not fly without it, and if you throw left handed you will have to reverse this setup.

Two pads (one top, one bottom) are hot glued to the left wingtip (right handed throw) and a carbon blade is mounted into them with CA glue (the blade on the plans is much larger and represents what I am using now - the original was uncomfortable and eventually broke)

A block of foam serves as the nose cone, and it is slotted to friction fit onto the front of the fuselage.

Use masking tape to roll an 8 1/2x11 sheet of paper into a tube matching the nose plug. Tape the tube to the nose cone, and you have a sheath which protects your electronics and tremendously improves the aerodynamics of the plane.

Congratulations! Your new Spinster DLG is finished and ready for flying.

Again, what has been presented here is only a sampling of the build process and several steps have been skipped. Read the full build guide to get the complete picture.

Now that the model is flyable, you need to program your radio to fly it effectively. 

Be sure to enable dual ailerons on your transmitter so that your flap function droops both flapperons 1/8”. You will need enough elevator down travel that the elevator trailing edge lightly touches the tailboom at full nose down. A similarly large amount of up travel should also be enabled. Get as much rudder travel as possible. Your flapperons should deflect 20 degrees up and 30 degrees down travel, and you should mix throttle to flaps so that at full throttle position, the flapperons are neutral, and at zero throttle, the flapperons are fully deflected downward.

Mix a momentary switch readily available to your left hand (if right handed) to mix in 5% up elevator for launch. You will hold this switch while spinning and release it immediately after the model leaves your hand so that it pitches the model straight up and then allows it to continue straight until you nose it over.

Balance your Spinster 40% back from the leading edge at the wing root to get started, and trim the model for a flat, fast glide with flaps neutral. Adding flaps should trim the model for minimum sink rate. As you get more comfortable, you can move the CG back until the model becomes marginally stable for maximum glide performance.

Visit the RCGroups Hand Launch forum for advice and programs to install on your transmitter for maximum utility with your new DLG, and watch Flite Test’s Discus Launched Glider video to learn the correct launching technique.

If you have any further questions, you can contact me directly through the contact form at J&H Aerospace.

COMMENTS

ChandlerRC on May 9, 2017
Beautiful, graceful plane! With lots of technology packed inside, though each piece itself is pretty simple. True gestalt!

I feel like such a Luddite that it took me so long reading to get that DLG means Discus Launched Glider! Doh! Thanks for the article.

-- Mike

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Razgriz on May 10, 2017
looks fantastic but the wingspan is a little unclear and i would like more information on how to make the wing, like a tiled pdf just like if you want to build a FT-plane or just the dementions.

have fun flying,
-- Jeroen

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Razgriz on May 10, 2017
sorry did forget to read the google drive links, i still dont know how to print it out in multiple A4 at 1,5M wingspan, please help =)
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FAI-F1D on May 11, 2017
I'm still working on getting tiles .pdf plans available. They will be posted in the google drive account when finished.
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donalson on July 19, 2018
are these pdf plans still in progress?... what is the wingspan on this?... love the idea and it seems to be about the only affordable way to give DLG a try... thanks for the work :)
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NCC1701 on January 14, 2018
Are there tiled plans available? This looks like great project. I knew someone who made a 1.5m out of dollar foam and strengthened the wing with fiberglass cloth. It lasted for years with some really amazing throws.
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Spinster, the foamboard beginner DLG