COMPLETED Gyskelion Build Thread--Non-Competition Helicopter

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BABAR

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Okay, here goes.

Gyskelion is a three rotor helicopter. Up front for safety purposes (especially given the drought and recent fires) please note this is an ENGINE EJECT rocket, so caution is REQUIRED when firing this puppy in drought ravaged areas (or any dry grass or timber.):y:

Uncommon (I'm afraid to say "unique" as somebody will always correctly find out it has been done before) factors for this rocket

Dental Floss Reinforced Rotor Hinges
Engine Eject Ring Retention for Rotors
Pyramidal Nose "Cone" on a helicopter (Dirt Cheap!)
Integrated Fins and Rotors (note this has been done on FlisKits TiddlyWink)
Using RotorStops to Displace Pull Strings for more reliable Rotor Deployment

Comments and modifications welcome. If you choose to build this and deviate from plans here (and this is encouraged) please feel free to contact me ahead of time. Sometimes there are REASONS things were done a certain way, and modifications MAY not work. :sad: Just trying to help out here.
 

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BABAR

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Parts:

One sheet 4"x36" balsa, 1/8" thick for RotorFins

Scraps of 1/16" balsa for RotorStops (will be laminated) (one piece about 2" x 6" should be enough)

Scraps of 1/4" balsa (could use 3/32")

2" piece of BT-20

2 plastic "cards" Key cards from hotels are good. Old credit cards. Whatever

Dental Floss. Must be waxed and mint flavored (kidding-- waxed, unwaxed, flavored or not-- all good.)

Old Used Estes Solar Ignitors (for the wire--- love this stuff for Pull Band Hooks!)

Card Stock (can use manila envelopes, poster board) one piece 8x11 should be fine

Duct Tape-- Color Optional

Stout Cord (I use Kevlar Thread, but doesn't HAVE to be flame resistant)

Tape (I like mylar for color)

More Card Stock (the Godiva Chocolate wrapper worked quite well.)

Thick CA glue (strongly recommended for laminating the rotor stops)

Thin CA glue (required for tightening the floss)

Wood Glue

Tools required: Good SEWING NEEDLE that can handle your floss

Tools helpful: an 18 mm hole saw is EXTREMELY helpful in cutting the holes in the cards, but you can cut this hole by hand (it is a PITB that way, though.)
 

BABAR

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This is that 4"x36" sheet of 1/8" balsa. You will cut 3 rotors out of this, and 3 fins. The dimensions are listed on the pics. The rotors are 2" wide, with a 45 degree angle tail cut. The short side is 15", long side 17". The Fins are also 2" wide, short side 5", long side 7".

Similar to many of the Edmonds Gliders, sanding is NOT required for this rocket, but if you desire it, the time to sand is BEFORE you draw the lines and cut.

GyskelionBoardLayout.jpgGyskelionBoardLayout2.jpgGyskelionBoardLayout3.jpg
 

BABAR

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Templates2.jpgCut out the basic rotor and fin lines first. Here are the templates for the other cuts for the hub section and the slot.

Mark these on the Rotors

Note the ANGLE on the hub template is 10 degrees. The slot is labelled as 1/8", probably should be 3/16". DO NOT CUT THE SLOT YET!
 

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Here is the cut between rotor and hub section

HubCutDimensions.jpg


HubCutDimensions2.jpg
 

BABAR

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Original Gyskelion and Whopper Flopper Chopper had the rotor stop simply glued on the outside of the rotor. But over time, particularly with the WFC, this joint tended to break. So now I cut a slot and reinforce it.

Because slot goes WITH the grain, you are likely to split the balsa if you don't put some support in place pre-cut.

Pics will probably be out of order. SlotCut.jpgSlotGuide.jpgTapeCABackup4Slot.jpg

From the OUTSIDE (the side you marked) of the Rotor, use the needle to poke a hole at the bottom of the slot. From the inside, mark where this hole is. Now from the INSIDE, put a short piece of masking tape over the hole. Put a couple of drops of thin CA on strengthen the bond. This should keep the wood from splitting.

Now cut the slot. It is labelled 1/8", since the laminated 2 pieces of 1/16" balsa of the rotor stops tends to swell up a bit, doesn't hurt to bump this slot up to 3/16"
 

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These have been previously demonstrated on the Whopper Flopper Chopper. Tape hinges and double tape hinges are nothing new. I have found however that adding dental floss (thread would probably work, I like the floss cuz it is stronger and handy, since it comes with it's own cutter attached) GREATLY strengthens these hinges (balsa will break before the hinge.) They are easy to attach and dirt cheap.

Note angle on the Gyskelion is 10 degrees, not 15 degrees (although 15 degrees would probably work).

Basic Diagrams here for WFC.FrontHingeGraphic1.jpgFrontHingeGraphic2.jpgFrontHingeGraphic3.jpgWFC_HubHinge1.jpgWFC_HubHingeGraphic2.jpg
 

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Cut duct tape strips about 2cm wide. With the Hub Piece and Rotor Pieces aligned, put the outside pieces on first (two pieces, one on each side of the slot.) Press/burnish these down HARD into the balsa.

Again pics are out of order

Now fully flex the hinge. Put a single strip of tape across the INSIDE of the hinge. Press it down hard on the EDGE of the hinge first, then press/burnish the remaining tape starting from the edge back along the hub and rotor sections.

InnerTape.jpg


OuterTape.jpg
 

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PreHolePlacement.jpgPullStringAttachmentInside.jpgPullStringAttachmentOutside.jpgIt is a little easier if you poke the holes with the needle BEFORE you try to sew the hinges into place. Helps to put some thick balsa behind the rotor and hub to give you a landing zone to pass your needle through. If your balsa is really tough, doesn't hurt to use some pliers.

From the inside, poke 2 holes about 5 mm and 10 mm inside each edge, at the top and bottom of your tape.

I didn't take enough pics, these additional pics show where the threads will go.
 

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Key to the double tape hinges is "sewing" them into the balsa. My previous experience with tape hinges (without thread or floss) was that they tended to pull off the balsa, was impossible to keep them "tight." I use dental floss. I'm not sure if the strength really help, I think most of the strength really comes from the tape (I use standard duck or duct tape---I just checked and both are accurate terms.) Most of the STRESS is at the lateral margins of the hinges (in fact, you could probably just put a small tape hinge on each lateral edge--- but I am guessing it wouldn't be as aerodynamic.)

In any case, I probably do overkill with the floss, the main function is to keep the tape closely applied to the balsa.

When passing the needle through the CENTER of the hinge, always pass it from inside to outside. That way you are sure to go through the center of both the inner and outer piece of tape in the middle of the hinge.WFC_Fin_Hinge_Inside_Holes.jpgWFC_Fin_Hinge_Inside_Threaded.jpgWFC_Hub_Hinge_Thread1.jpgWFC_Hub_Hinge_Thread2.jpgInsideRotorStopReinforcement.jpg

I am using some pics from the Whopper Flopper Chopper. Since that time I have changed to putting the support threads only on the edge. I don't know that it makes much difference to wrap around the side, but it doesn't hurt. Obviously for competition helicopters (which this is NOT) every 100th of a gram matters. This is designed to give nice flights on a C engine that will USUALLY stay within a park size field, as long as winds are not much over 5 mph.

Once the floss is tied (put the knot on the inside, to keep it out of the airstream) it is wicked from the inside with thin CA, to seal the deal. This way even if a part of the thread breaks, it won't unravel and the joint will still hold. This joint is stronger than the balsa it is attached to (at least up to 1/8" balsa.)
 

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The Rotor Stops will exert stress parallel to the grain of the hub and rotor. Over time I have found this tends to be a weak spot. So now I add a piece of cardboard on the inside of the rotor and hub for support. It also provides a "base" for firmer attachment of the stop itself. These were cut out of the cardboard wrapper for a Godiva dark chocolate bar.InsideRotorStopReinforcement.jpg
They are attached with white glue.
 

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These pieces need to be light, strong, and take stress in two different axes (axises? axi?) My solution has been to cut two pieces out of 1/16", one with the grain, the other 90 degrees OFF the grain. Because of the shape, these are a BIT difficult to cut out (they tend to split.) Once you have them cut out (you will have a total of 8, 4 one grain, and 4 the other grain), match up the opposites. I use THICK CA to glue them together. The reason is that both white and wood glue will cause them to WARP. Yes, you can stick them between wax paper and let them dry inside a book. However, the thick CA works great, it is fast, it doesn't warp, it doesn't require ANY compression at all, and it makes them as hard as a rock but not particularly brittle.Templates.jpg

Forgot to take a pic, the template for the rotor stop is in the middle.
 

iter

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Very cool! Thank you for sharing your build.

Ari.
 

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One thing that would be easier on future builds. BEFORE laminating the two pieces together, put a shallow (say 30 degree) bevel on the outside edge (marked in red on the pic.)

When you match up the pieces, put the bevel on the INSIDE between the pieces (this is counter-intuitive.) This will form a "notch" on the outside or lateral edge. This will help to hold the pull string in place at launch.

Once the glue is dry from laminating the two pieces, wick a touch of thin CA to "harden" the edges.

In this case and previous builds, I have just carved this notch after attaching the pieces.

TemplateRotorStop.jpg
 

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Put a small amount of wood glue in the rotor stop slot.

Insert the "tabbed" end of the rotor stop into the slot. Bring the stop as far forward in the slot as needed to make sure the hinge opens to the appropriate range.

Once dry, small fillets are adequate to reinforce this.RotorStopInSlot.jpg
 

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The pull strings will be attached at the forward edge of the hub. Because the grain is parallel to the hub, just tying it into place won't be strong enough.PullStringAttachmentInside.jpgPullStringAttachmentOutside.jpgPullString8inches.jpg

Use a small (about 3x5 mm, grain LONG direction) piece of 1/16" balsa, attach to inside forward edge of hub, the grain of the reinforcement is PERPENDICULAR to the Hub grain. This will provide an attachment point for your pull string.

I use Kevlar Thread for the pull string, but any stout cord will do. This is NOT exposed to the ejection blast, so heat resistance is not an issue. I would NOT use floss, as it tends to fray.

After passing this with a needle just below the attachment, run the cord over the top edge of the attachment (I carve a small notch) and over the top of the hub. Measure down 8 inches, mark the cord here. Tie a loop (about 1" diameter) with the mark at the APEX of the loop. This will be where you will attach rubber band.
 

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Sanding is NOT required for this model. I have been doing this long enough however that I feel a bit guilty not doing SOMETHING with the the fins, so I round the forward, lateral, and trail edges.

Use wood glue to attach the Rotors to the Fins. I put this on wax paper, put another piece over it, and weight it down with magazines on a flat surface to dry.SewnInMotorMount.jpg

Here is a picture of the finished joint
 

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One thing unique about Gyskelion, it is a Tubeless/Fuselage-less helicopter. Meaning there is NO center support connecting the Nose to the Motor. The motor mount is in fact attached to one of the rotor-fins (sorry, definition: once I attach the rotors to the fins I call them rotor-fins.)

The motor mount is taking a heck of a blast with the engine ejection charge, and the mount is LATERALLY attached to the rotor-fin. So this joint takes a LOT of stress.

Best material I have found for these is the plastic card material that comes on Hotel Keys, SOME gift cards, old credit cards, and some ID cards (I had some old insurance cards.) Single sheet balsa will not work (as the stress is in multiple planes), plywood is too heavy. I have tried card stock, but it has not worked well, tends to bend.

In a sense, you are cutting "centering rings" (In this case TRIANGLES) for a triangular shaped "body tube." Comes out to an equilateral triangle 48mm on an edge (fits inside the 2" wide rotor fins.) Cut out a TEMPLATE out of card stock, put an 18 mm hole in the middle (trace around an A, B, or C engine casing.) You can get 3 of these out of one plastic card, but to start with I'd go for 2. Mark the outline on the card, including the inside hole.

Tools that made this MUCH easier were 18mm and 20 mm hole saws I got on E-bay from China. The 20 mm works for the engine mount, the 18 mm for the retention rings. Reason I say go for 2 at a time on the cards and givve yourself some space between them (you need 4 anyway) is this: Once you rough out where on the card the hole is going to be, drill the two holes (two each card.) If you are doing this with a hand drill and you are uncoordinated, like me, you will probably be off the center of your marked hole. So once you drill your hole, put your card stock template back over and mark the "real" edges of the triangle. You can then cut out the triangle with sharp scissors.CardCuttingTemplate.jpgCardHoleSaw.jpgMotorMountConstruct1.jpgMotorMountConstruct2.jpgMotorMountPlugs.jpg
 

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The rings are BT-20 to BT50 Centering rings. They provide a little more support of the tube/triangle joints.
The Buttresses are an addition I've made to latest Gyskelion. They are cut out of 1/4" balsa, and provide a more robust joint as well. The round balsa circles are bulkheads, again I cut two and place them with the grain in 90" opposing orientation. They go in the forward end of the tube. Need a good forward fillet on these, as these will have to withstand the ejection blast.
 

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Pics of completed motor mount. Also reinforced this with floss and thin CA.

This is attached on the INSIDE of one of the Rotor-Fins. It will be aligned with the inside of the LEAD EDGE of the ROTOR (the fin extends of the trail edge of ROTOR)

Again some definitions are in order. When referring to lead edge of the ROTOR, this refers to the motion of the ROTOR during DESCENT (spinning.) When referring to lead edge of the FIN, this refers to motion of the fin during ASCENT (boost.)

The BT-20 Tube Segment is 2" long. The Bulkhead Discs are inserted 1/2 inch at the forward head. So that leaves 1.5" to hold the engine casing. The engine casing is about 2.75" long. The tail or aft end of the tube of the motor mount is placed 1.25" from the tail end of the ROTOR-Fin (trail edge of the fin, if you like.) Therefore with the engine casing loaded, the aft end of the casing is flush with the bottom of the rocket in launch configuration.

I drilled small holes in each of the 4 "corners" of the motor mount base (through the plastic and the balsa supports). Once the mount was glued in place, I "sewed" it in with floss. I cannot emphasize how much stress these two joints take, especially since the attachment is 90" degrees of the direction of the ejection force. This has been a point of failure on some of my earlier versions of this design.

Mass of the motor mount about 5 grams. I probably overbuilt this in my latest version.

The sharp eyed will see a piece of balsa on the inside of the rotor fin below the balsa. Ignore this ("Pay no attention to that man behind the curtain!")

MotorMountAttachment.jpg


MotorMountMass.jpg
 

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Those patient enough to handle my long windedness may have been wondering how the heck this works. Probably a good time to post the video of this (should have done it sooner)
[video=youtube;vs_dkMWvXSs]https://www.youtube.com/watch?v=vs_dkMWvXSs[/video]

This from a previous version of Gyskelion, but the differences are minimal

Here is a Flight Video (I'll brag on this one, I wish ALL my flight videos came out this well.)

[video=youtube;t41u3quyi5M]https://www.youtube.com/watch?v=t41u3quyi5M[/video]

Anyway, the Retention Triangles go on the other two rotors. The holes in the plastic triangles are 18 mm, rather than 20 mm for the motor mount. They are otherwise attached similar to the motor mount, aligned with the lead edge of the rotor. One is placed about 1/8" below the aft end of the motor mount tube, the next 1/4" aft of that. Likewise these are "sewn" into the Rotor-Fins with floss and thin CA. Surprisingly these also take a good bit of stress.RotorRentionRingAttachment.jpgRotorRetentionRingAttachment2.jpgRotorRetentionRingMass.jpgSewingRotorRetentionRing.jpg

again ignore the little balsa tabs below the retention rings.
 

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These are something I REALLY like. You need a way to firmly attach the rubber bands that will withstand launch, ejection, and landing. But you'd like to be able to remove them quickly at recovery time. And you DON'T want to have them getting tangled up in the trunk of the car (which my previous "hooks at the ends of strings" did ALL the time.)

Started making these with paper clip wires. Then I looked at my expended Estes Solar Ignitors (igniters-- both spellings are correct.) Ridiculous, those floppy things couldn't hold a rubber band. BUT, if the hook has a very NARROW diameter of curvature (or none-- you can just bend the thing sharply over the band) it works, and the band will break before the wire gives out.

Because they are small, you DO need some extra support attaching them to the balsa or they will just pull through. I attach them to little pieces of the same plastic card that I use for the Mount/Retention Triangles. I DOUBLE the ignitor wire (actually 1/2 of each ignitor, pulling the little tiny piece of nichrome off) so the exposed tip is NOT sharp. Twist it, poke it through a PRE-punched hole in the plastic piece (done with a heavy needle, pliers, and a backing of 1/4 inch balsa onto a cutting board-- do NOT poke yourself in this process.)

The attachment point is just aft of the Mount or Retention Ring on each Rotor-Fin

PullBandHookConstruction.jpgPullBandHookConstruction2.jpgPullBandHookPlacementInside.jpgPullBandPlacementOutside.jpg
 

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As a sport rocket, I built this one to last (although Gyskelion 1 made it through about 15 flights before starting to show some real wear.)

Cut 4 strips of 1/4" balsa by 1/4" by 1.5".

Using wood glue, attach on to the inside LEAD edge of each hub. Apply a fillet. Once dry, sand the outside edge of this to 60 degrees.

Prepare 3 piece of masking tape, each about 3 inches long.

Glue the hub pieces together, use the masking tape to hold in place. When dry, add a fillet at each new joint.BraceFront.jpgHubFrontView.jpg
 

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SewingSupportHub.jpgSewingSupportHub2.jpg

As a reinforcement to the glued joints, I also use a drill to place tiny holes across each joint just above the hinges, then use a needle and floss to "sew" the joints closed. As usual, wick CA into the floss to seal the deal. Probably overkill, but I've never had a failure of these joints. I do the same thing on my Spyder Video Rockets.
 

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NosePyramidTapeOutide.jpgNosePyramidDimensions.jpgNosePyramidFoldandHole.jpgNosePyramidTapedPullStrings.jpgNosePyramidComplete.jpgI've read that for rocket KITS, one of the most expensive parts is the nose cone. Not a problem on this bird.

I've used poster paper, now I am using left over manila folders (we have some colored ones.)

The picture shows the dimensions (although I'd have to say I have customized these to each one, so your measurements may be a bit different by a couple of mm depending on how the hub joint came out.) I use the back side of the 11 blade hobby knife to score the fold points. A hole punch places a hole in the middle of each "tab" just AFT of the fold point, then cut a line from the edge of the hinge to the hole. Makes it easier to place the pull strings. A piece of mylar tape adds a little flash to the joint.
 

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Finished nose pyramid will slide over the hub. Thread the pull strings through the holes.

Make sure you have the Nose Centered (check from all three sides.) Tape on.

Use a Larkshead knot to place a #16 rubber band (you can buy a bag of a gazillion at any office supply store for about 6 bucks-- it will last you almost as long as a bale of dog barf wadding) onto each of the three loops of the pull strings.

Put a couple of short (5 mm ) launch lugs along the TRAIL edge of one of the rotors. I use a 1/8" stand off to give a little clearance over the hinges and the nose pyramid.

Make sure the engine fit in the motor mount is LOOSE (not "lose"!) It should almost fall out. If it is tight, put some sandpaper around a MINI engine or some equivalent diameter, put it up there and sand the inside of the tube.

Close the hinges. The holes of the motor mount and the retention triangles should perfectly line up. Slip an engine in (B6-4 WILL give you a safe but very short flight, C6-5 is optimal.)

Pull the rubber bands over the Solar Ignitor hooks. You can "crimp" the wire down a bit if you don't think it will hold.

Important step! Pull the forward ends of the bands OVER the Rotor Stops so they fall into the "notch." This holds the pull strings and bands AWAY from the rocket and (I believe) significantly improves the "moment" of pull and give a much more reliable Rotor deployment.

Put in an ignitor, and you are good to go.

Thanks for reading this. Comments (particularly suggestions for improvement) always welcome

GyskelionPad.jpg
 
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