Living Room Rubber Band planes

23 November 2022

Bearing

tube bearings

pig tail bearings

plastic tubes like used pens, wire passing through the diameter. Hot wire can pass through the plastic.

thin aluminium strips from discarded drinking cans. They are thin, can punch through with thumbtack.

rolled up thin aluminium strips from discarded drinking cans. No need to punch through.

same aluminium but in U channel

thin aluminium strips wrapped around balsa structure, use beads.

washers

can be thin aluminium strips from discarded drinking cans, maybe of any shape not necessarily must be round

Spars

sq/rect balsa

round sticks, wood/bamboo

Blades

balsa

card

plastic

aluminium

28 February 2022

Wobbly propellers? I thought this out over the weekend.

2 balsa spar strips are placed side by side on the cutting mat. A perpendicular line is scored across the 2 strips to give a shallow groove. Flip 1 spar over to the other spar and glue the strips together, with a pin at the scored location. When the pin is removed, there is a pilot hole for drilling out.

Much like sanding a balsa trailing edge, sand the ends of the propeller spar to the angle required for gluing on the propeller blades.

Some variations:

• The 2 spars overlapped throughout. (strongest/heaviest)
• The overlapped joints are kept short. (lightest with the spar offset to one side of the blades)
• The spars may be deeper. (strongest/heaviest/accurate/U-turn hook/rotor if the spars are later sanded to the rotor dihedral)
• Taper the spars. (lighten)
• Propeller blade ontop, middle, or bottom of spar, fixed, folding or hinged.
• The 2 spars may be overlapped at an angle (rotor dihedral). 

I just thought of this:

If the spars are deep enough, cut an angle template with a slot to slip in the spar. The angle presented by the template will give some guidance to the amount of tilt the blades are to be glued on the spar. A variation of a removable template is to make 2 permanent oversized templates, which are glued to the spar and can be sanded down.

Maybe I can do a free-spinning rotor for an auto-gyro if the groove is enlarged and thin aluminum bearing is glued top and bottom of the hub.

24 February 2022

pig tail wire thrust bearing

The front bearing will not be flat and continuous because the wire overlaps itself. Grinding is too much work and the actual bearing surface is the washer/bead. So I think an incomplete loop is enough and a larger tolerance wire bearing is easier to get right at slight efficiency loss.

1. Cross the wire and mandrel perpendicularly and grip both with a pair of plier.
2. Loop the wire once around the mandrel.
3. Remove the mandrel and slide a side cutter along the wire to snip off the overlapping end.
4. Flatten the twisted loop so they are now on a single plane.
5. Grip the flattened loop and bend the wire 45 degrees perpendicular to the axis of the loop.
6. Make another 45 degrees bend so the free end of the wire is now parallel to the flattened loop.
7. Insert mandrel through the loop and cross the wire.
8. Grip juncture with a pair of plier and spiral loop the wire once around the mandrel.
9. Trim the wire to length.

motor hook

If I am using paperclip, the diameter of the wire is large, so I don't think I want to pierce the propeller spar, instead I think I can tie it below the spar. 

1. Form loop
2. Grip loop straighten shaft end, trim hook end
3. Twist loop to line the loop with the shaft
4. Insert 2 beads
5. Bend 90deg 

propeller

1. bamboo spar dowel
2. propeller blades
3. Make jig to assemble propeller

22 February 2022

The most difficult to get right: propeller, mount and shaft.

I have tried the plastic tube from cotton bud for the spar, it didn't twirl true. I must have 'drilled' and glued inaccurately. 

Got a few ideas from the internet:

• 3/8"-1/4" square balsa with saw cut
• Glue 90degrees bend to one half of spar before butt gluing the other half
• Tie 90 degrees to one side of the spar
• pig tail wire thrust bearing
• tube thrust bearing

My ideas:

• Using used gel pen: works like the internet idea for propeller hub, another short length can be drilled so that it can be a propeller hanger for stick fuselage, if holes are oversized, wedges can be used to adjust thrustline
• Prop hub: Tie 90 degrees bend to bottom side of the spar. Or make something like a hook?
• Prop hub: Use aluminum strip from drink can, pierce a hole, bend into a channel, thread the bend through the hole, UHU balsa/bamboo spar over the bend and rub close the channel.
• Prop hanger: Use aluminum strip from drink can, pierce 2 holes, bend one edge to a channel and the other edge at 90 deg, snip away so that it can be UHU glued to motor stick. The rear hole can be snipped, bent open to receive the motor shaft and bend back to secure the motor shaft.
• Use plastic coated paper clip for shaft. They are thinner and came with plastic coating at the hook portion so it will protect the rubber?
• An alternative to forming a hook in the shaft for a winder is to form an intermediary double hooks that hook on to the spar.

Plastic coated paper clip for shaft. They are thinner, more malleable to bend accurately and come with plastic coating that'll protect the rubber from burrs. After the hook end is formed, strip the coating away from the remainder. It might be knocked off-true, but since it is malleable, it is easier to bend straight. It is easier to bend the shaft until it spins true and the propeller also spins true. I suspect it is only usable for small living room rubber band planes where the rubber motor does not pull too hard. So it can be paired with the drink can prop hanger because that is also usable in weak pull.

Just tried the plastic coated paper clip. I used the inner bend as the rubber hook, straighten by hand, tweaked the inner bend to a rubber hook shape, used a side cutter to snip off the bigger bend and the excess at the motor hook, seems that the pull point is inline with the straightened shaft, used a side cutter to bite into the plastic coating against the hook, pulled the plastic off. Tried to straightened further by pulling (didn't work, got a lot of grip marks instead). Rolled on wooden block shows it is not straight, but maybe it is good enough. The exposed wire looks thick, definitely thicker than a clothesmaking pin, close to 1/32". Because my motor hook has a long free end, it is heavier on that end so I think the 90degrees bend can be bent away from the hook leg to balance a bit. I stopped at one, but maybe I should do several to see if they can be improved upon, for example, not using the plier to try to straighten? And I can try them with all the different ideas for hub and hanger.

The double hook is simply a large paper clip, straightened then folded against itself and the ends are then bent to hook with the opening in the direction of winding. 

 

29 November 2021

The aim of this exercise is to use 2 pieces of regular rubber bands looped to form a 6" 2 strands motor. I have not tried it before, but I think that when compared to slipped looped rubber bands, the one slip loop should be lighter than the square and 8 knots commonly used. Besides, if it is meant to inspire people to trying it themselves, the rubber source should be easily available. I will always have conveniently at hand regular rubber bands 'fresh'. 

This link is great!

scraps (indoorfreeflight.com)

Plastic tube from cotton bud. Use for hub? Difficulty is drilling the 2 holes in the 1/2" long, 1/8" plastic tube. How? Take a 1" tube, tape from one end, 1/4" of masking tape around the circumference. Then lay it on flat, tape on bare end, mark 1/2 thickness on both sides of the tube. Use a pin the punch/melt the 2 holes. Remove remnant of tape. Enlarge the 2 holes so a wire from a paper clip can pass through, don't need to be free wheeling if not making a free wheeling hub. Trim the tube so that both ends are at 1/4" away from the holes.

Propeller and tail hooks are from paper clip. Hand winding from the propeller with a fat finger is probably harmful. Make a loop on the propeller hook to allow use of a winder.

Winder: A Z crank with no gearing. Take the largest paper clip and straighten the wire. Make a hook at one end. Insert a full plastic tube. Bend 90degrees, leave a 1" arm and bend another 90degrees so that the remaining wire is parallel to the hook end. A winding stooge is needed.

Winding stooge: maybe a screw eyelet on a wooden block long enough to step on and with a S hook.

Procedure: After winding rubber bands on the stooge, unhook the winder and hook the rubber end on to propeller. Pinch the hub to stop propeller from spinning. Unhook rubber from stooge's S hook and hook onto tail hook.

How to simplify it so that the rubber can be winded by a finger? A longer propeller hub. How long? 2" overall allows 3/4" for the finger and 1/4" for the propeller blade. Seems iffy and will destroy the blade setting or even pull out the blade.

Motor stick:  Seperate motor stick from plane so that Attach motor stick with tape to model? This allows thrustline and even CG to be adjustable. Use bamboo dowel like that of the propeller spars. Use 2 split plastic tube lengths to be intermediary between motor stick and model. Glue the 2 plastic tubes to model plane and 'clip' on motor stick. Motor stick will twist but the tail hook will stop the motor stick from spinning freely. Space the motor stick with a stopper so that the rubber won't bind or slap against the model plane. Or a stopper can be a short length of balsa stick glued to the motor stick.  A thought,  longer or shorter motor sticks can be used, not limited to the length of the fuselage.

Simplify model plane construction. Use hot wire cut thin polystyrene foam sheet for wings and tails and slightly thicker for the fuselage because the compression and torsion from the rubber band is freed from the model plane.

 

Dihedral, holding it there

16 November 2022

When there is no depth, the joint is weak and it can fail. Clapping wings is a catastrophe.

In Farman Moustique, the stressed area was exchanged from butt joints to the area in contact with the fuselage. Struts will have similar effect for other models.

If there is no depth, such as a single foil wing which uses only leading and trailing edge sticks and positioned above a stick fuselage, an idea is to add thin aluminium strips to the leading and trailing edges. It may still bend but it won't break and can be bent back to the dihedral angle. Aluminium, plastic or paper tubes will also work, the latter being rather weak. Paper tubes may also be made in placed by wrapping tissue around the leading and trailing sticks, but the centre rib will get in the way, so as an alternative, the centre rib can be added after the joints are wrapped.

3 cylinder model

17 October 2022

Over the weekend, I played around with the model and did this:

Mounting the Electric Motor (not the capacitor yet)

1. Cut one tooth pick into 2, about 2/3 long and 1/3 long
2. Glue the 2 pieces at opposing sides of the electric motor. I choose to have the wiring away from either picks.
3. Tape the picks and motor together.
4. Poke into the nose of the fuselage.

I didn't cut the reinforcing hard card base for the 2 picks. I think the base of the electric motor will not enter into the soft nose and also since it is 2 picks the lateral load should spread sufficiently.

The Engine

With the electric motor in-placed at what seems to be right, I proceed with the engine modelling:

1. Hot wire cut 3 pieces from drinking straw. I made a cube jig for this, the result is straightish but not really square, good enough.
2. Cover the tubes with silver tissue: 
1. Cap tissue: tissue over one end, gum it to the sides.
2. Cylinder tissue: tissue around sides, capturing the cap tissue ends.
3. Fin tissue: Draw black parallel lines, cut 3 strips, roll around the cap end.
3. Cylinder base:
1. Cut 3 strips
2. Cover with tissue on one side
4.  Assemble cylinder to base:
1. Glue 2 cylinders to one end
2. Glue last cylinder to middle
5. Glue the base onto the electric motor.

The Capacitor

This was left to the last because it can help to trim the model. I only did the casing for the capacitor to slide in. It is a section of a very large diameter straw with the piercing end, cut with hot wire cutter using the cube jig. The piercing/sloping end allows the slightly protrucing capacitor charging jack to rest and not to twist around. This tube was covered with silver tissue. The intention is to mount the tube like an underslung canister at the nose of the fuselage. It is not a scale feature but it is a fake feature and is convenient and easy. I don't have to cut slots in the fuselage for the capacitor. With the canister mounted, perhaps by a wire hook or just glued to the underside of the fuselage, the capacitor can be inserted or withdrawn, thus allowing the trimming of the CG.

Choice of having the capacitor below the fuselage is for pendulum effect and also thrustline.

Thrustline above CG will have a down thrust moment, thereby less angular thrustline will be required. The centre of drag should be nearer to the wing as that is the largest drag producer. Who knows, maybe the blocky undercarriage may also bring the drag centre closer to the thrustline and that would be ideal.

12 October 2022

Variation of yesterday's idea.

The engine will be the point of interest. Every pair of eyes will be drawn to it when they look for details. A bit more detail is needed.

Each cylinder is not a single cylinder but 2 cylinders, I can fit a bigger straw over a smaller straw. Or if I can't find 2 appropriately sized straws, split one to fit over the unsplit straw or maybe I should just wrap some paper/tissue on one end of the straw so that outwardly, it appears to be of 2 diameters. 

1. cut three identical length straw
2. cover with black tissue
3. strip of silver tissue with parallel black lines
4. wrap with strip of paper to bulk up
5. wrap with striped silver tissue over the paper rolled open end
6. roll the pre-striped tissue over the paper tube end, covering the tissue tabs of step 5 if any.  

The task now is to think how to make a mount that incorporates 3 tongues at the right positions (to glue on the above made cylinders), allowing electric motor to be centrally located fit and generally look like a crankcase. For durability, I want it to be made from flexible "EVA" foam.

3 prongs (120 degrees apart), hexagon (crankcase), rectangular (fuselage nose), motor pass through or insert through...

Ah ha! 

The electric motor with its two toothpick legs is to be inserted to the nose of the fuselage. As the fuselage is only white styrofoam, it would simply tear on each crash. I need to strengthen it.

The nose presented is a small rectangle. An idea is to cut a piece of rectangle from thick card and have  2 holes drilled/punched through to prevent the 2 picks from tearing away. This card has sufficient area as it covers the entire nose and does not interfere with the re-inserting of the picks (for down and side thrust adjustments).

The engine can basically be a piece of flat EVA foam with 3 tongues to which the 3 straw cylinders are attached. The foam piece is slotted at the bottom to clear the electric motor. This 3 cylinder engine is glued to a strip of EVA foam which is in turn glued to the hard card base. This strip need not be fashioned, it could be a 'U' shaped piece as its purpose is only to hold the engine to the nose. Yes, the crankcase is missing, but it's only a little bit. But if the visual bothers me too much, I can add thin card to slot over the EVA tongues before putting in the cylinders. The thin card is to cover the 5 sides out of the hexagon shaped crankcase.

Slightly more work is to cut and fold to make a hexagonal front cover, leaving the bottom and rear uncovered. The bottom is missing to clear the electric motor and the rear is missing to glue on the EVA mounting support.

1. Card nose
2. Insert electric motor, solder and mount capacitor
3. Test flight
4. Adjust CG and thrustline
5. no need to remove propeller and I can glue the engine and crankcase unit.

Oh!

Why bother with 3 tongued EVA piece? Just make the card crankcase and have enough gluing area to the base of each cylinder! No slots, no EVA piece and the cylinders can be glued staggered slightly! Just make the engine mouting EVA strip longer to support on the inside of the crankcase.

Hmmm...

Toothpick bound to the electric motor would be light and strong, but wooden toothpick is not bendable. How about something that can bend so that the thrustline can be adjusted?

Bind two wires (paper clip) to the electric motor? Or cut from stainless steel wire?

Another thought is matching the engine to the electric motor. The crank case would not fit snugly to the nose and the rear end of the electric motor would be offsetted from the centre of the fuselage.

Something to think about.

So, I will have to think how the engine can be glued to the nose (not the electric motor). Previous thought was a single looped strip glued to the rear of the crankcase cover, maybe I have to think how it can be glued to the rear of the engine (on the crankcase). The difficulty is how to fit foam mount to a hexagonal crankcase. Small short strips? Maybe inside of the top side of the hexagon behind the top cylinder and 2 stubs behind the lower 2 cylinders?

Oh! What if I glue a hexagon piece of EVA foam to the thick card motor mount? Then it is possible to locate the crankcase like a cap over this hexagon piece. 5 short straight strips can be glued to the hexagon piece to provide adjusting area as well as gluing area to the engine. 2 or 3 degrees off should not affect the fit since it is cardboard crankcase over EVA foam anyway.

11 October 2022

OK, I tried for an RC model but it was quite a lot of work for an untidy piece that I can not be proud of and I left it at that last year.

Now, for a 15" wingspan capacitor powered model, I think I will simplify a bit more so that it looks neater. The purpose is only to have something that suggests a motor from at least 2 metres away, and to consider that at the nose end, there will be knocks and bumps. Hey! My pilot is just an outline anyway.

At first I thought about doing up a single mould to make the cylinders by shrinking plastic tube. Then I drop this idea because any fins I put in the mould would unlikely be visible, much, since the shrinking will bridge over gaps and I am not going to try vacuum moulding. Paper tubes will look like paper tubes, so idea is dropped as well. Winding around with 3D pen was dropped because my experience was negative.

After much simplifying:

• mount is flexible foam to tack glue on fuselage's nose
• each base cylinder is strip of flexible foam with a slot to receive the cylinder top
• each cylinder top is just a piece of card paper glued at ninety degrees to the base cylinder

Frontal view is just 3 narrow rectangular strips equally spaced around, less disruption to the head-on airflow. Side and plan view will show some idea of cylinder tops. It should look the part from many angles when viewed 2 metres away, squint if necessary. 

1. Cut a card/paper strip and silver tissue both sides and draw in parallel black lines over the tissued sides. Cut 3 pieces for the 3 cylinder tops.
2. Cut 3 strips which has a slit/slot to receive cylinder top. If I don't want to cut a slit/slot, I could also leave it as that and glue the cylinder tops to its edge.
3. Cut a rectangular strip for the mount. Hot bend or glue strips to two opposing edge (for mounting to fuselage's nose). Hollow out for pass through or fit over of electric motor.
4. Assemble by gluing the 3 strips on the mounting piece, glue the cylinder tops to the 3 strips. 

After a while, I searched for Anzani engines and found photographs of actual engines. The cylinders is fairly uniform, the fins protruded only a bit. They were either black or silver. So instead of doing flat strips like steps 1 and 2 above, to improve the look, I revert to drinking straws:

• Draw parallel lines with black marker on silver tissue
• Cut a rectangular strip, the lined portion represents the fins, yes it is reversed, i.e. not silver lines on black tissue, but black oil based markers are cheaper and easily available.
• Glue tissue strip around a drinking straw and cut to length, repeat 3 times for 3 cylinders.
• Insert and glue the straw tubes to the 3 prongs of the flexible rectangular strips, with the strips at the back end of the straw for step 4.

8 June 2021

It depends what skill, tools, material and what size and weight of the model. In case of a peanut scale, my hexagonal crankcase is about 12mm OD and 10mm deep, and each cylinder is about 6mm OD and 10mm long.

The actual steps taken for the peanut model were:

1. Cut a strip of paper with tabs all-round, bend and glue together. Immediately place inside a circle template to adjust the hexagon shape.
2. Mark and cut from transparent drinking straw 10mm long segments with two slots, something like a 'E'. Two rings are next to each other on one end to simulate the finned cylinder, the last ring is at the other end and is the base of the entire cylinder to allow gluing.
3. Glue the cylinders to the hexagon.

Tips:

• Use circle template to hold the hexagon shape until the glue dries.
• Flatten the drinking straw to mark out the fins and base of the cylinder.
• Use scissors to cut the drinking straw to "E" shape.
• Open up the 3 loops and pass a small dowel through the 3 loops and finger roll to round the straw.
• Glue with UHU All-Purpose or POR, the near translucent cylinders and paper hexagon.

28 May 2021

To make something like the Anzani 3 cylinders in Y configuration for small aircraft models using bendy drinking straws in a fast and easy manner:

1. Crankcase is 6 sided. Cut strip of paper from photo-copy paper, mark 6 segments, crease on the lines, glue together and loop the strip around so that it is at least 2 ply thick to get a open ended hexagon. No need to make back or front to close because the motor will be there anyway and it is a very small engine model.
2. Glue small foam squares to 3 sides. Offset the squares so that when the assembled cylinders are glued on, the cylinders will also be offset in fore-mid-aft positions.
3. Extend the bendy portion of the drinking straw. Cut 3 equal length sections. Slit lengthwise if the bendy portion can not fit over the straight drinking straw.
4. Cut 3 lengths of the straight sections of the drinking straw. Slip the bending portions through one end, this allow 'exact' length of cylinders to be adjusted.
5. Glue the 3 cylinders to the foam squares on the hexagon crankcase.
6. Spray black, rub-in or dry-brush silver highlights.

Self-stabilised cylinders in case of crash?

1. As before.
2. Skip this step.
3. As before.
4. Where the cylinder shall meet the crankcase, leave a short 'tongue'.
5. Poke a slit through the crankcase to receive the tongues. When the tongues are at the rear, the cylinders can snap back and recover should they be knocked rearwards.
6.  As before.

Jedelsky style for small wings

11 October 2022

Respect to Mr. Jedelsky who came up with his jedelsky construction:

• thick balsa leading edge sheet (sanded to front-upper curvature later, making the leading edge stronger to withstand wing dings)
• thin balsa sheet rear of leading edge sheet (forming to the rear-upper curvature)
• identical ribs to maintain the airfoil (simplified one rib template for almost any wing planform and did you know that these ribs are longer then the wing chord for stable construction and excess protrusions shall be trimmed off after the top sheets are in placed?)
• if trailing edge at wing tip is shorter than wing root, washout results; vice-versa for leading edge taper and trailing edge taper towards wing tips. (automatically creating washout without causing stress to the wood components)
• when the wing tip is shorter than the wing root, the depth/thickness of the wingtip goes progressively lesser because the bottom of the ribs is trimmed off (automatically creating a tapered thickness across the span of the wing)

However, it is relatively heavier then a framework style wing construction, so it may be too strong (read "heavy") for small and very light wings because too much balsa is used. 

So the solution is to change this sheet construction to frame construction, but this loses some of its simplicity and adjustments have to be made and compromises accepted.

The first order of conversion may be using a rectangular section of thin balsa sheet to frame the trailing edge, leaving large area of wing that is rear of leading-edge sheet empty and to be covered by tissue. The front edge of this strip will present a slight bump air flowing underside, but this bump should not affect the airflow much because it is going to be used for a slow flying model and my priority goes to air flow over the upperside (and looks).

The second adaptation is to the ribs.

The jedelsky rib has the front as a straight slope and the rear as a curved slope to accept the trailing sheet. However, there is only a trailing edge strip in placed for a jedelsky frame-work styled wing, so the rear need not be curved. At the trailing edge receiving the thin trailing rectangular strip, it could be a straight slope as well. The original jedelsky idea is to leave the in-between proud of the rear edge of the leading edge and front edge of the trailing rectangular strip and when the glue has set, trim away in-situ to form that bit of curve for supporting the tissue covering. But each rib will be different for anything other than a rectangular wing planform because the leading and trailing strips are not paper thin. So this is not going to work, as I cared more for looks upper surface.

The compromise to make identical ribs possible is to make each rib to comprise of a lower main rib which is largely triangular in view for the gluing of the leading-edge sheet and trailing edge strip, and then an upper rib to support the tissue covering. These upper ribs are not identical, they have to be customised to each distance between the rear of the leading-edge sheet and the front of the trailing edge strip. It is not a cap-strip of consistent thickness; it is a trapezoidal extension on top of the lower main rib that is measured and cut to the actual distance.

   

Now, some checks for consideration.

It is going to be used for small, light, slow flying models. I would probably use 1/32" balsa sheet for the trailing edge sheet. This means the bump is equally small and on the scale of things, what is that over a mere few inches of wing chords? Maybe simple triangular ribs will be enough. If we view the model from 2 metres away, I think the 'bent' airfoil would look ok.

The main strength of the wing is dependent on the leading-edge sheet. Since the intention is to use 1/32" trailing sheet, the leading sheet should be slightly thicker, maybe a minimum of 1/16" for super light and upto 1/8" for rough and tumble. 

For 1/8" leading sheet, I think it is neater if the rear end is shaved to 1/16" or thinner for minimal sanding and better looks. So a simplified 'blank' for the 1/8" leading sheet is to have the rear edge shaved/sanded down from the middle of the strip to the rear end at 1/16", 1/32" if I am daring.

All the above is just thinking about it. When doing up for real, I may realise something I overlooked and adapt accordingly. 

Tethered flying

10 October 2022

There's a couple of ways for tethered flying.

Whip

Unpowered gliders is tethered to a string and then the other end of the string is tied around a long staff. I have seen this in magazine.

RTP (electric Round-the-Pole, Round-the-Pylon)

The power source is supplied to electrical twin-core through a commutator type contact at the pole/pylon to the electric motor in the model. By varying the voltage, the power variation cause the electric motor to spin faster or slower thus causing it to climb or glide. I have never tried this before and I'm sure I'll encounter many problems.

CL (Control Line)

This I have experience in my youth. One gets giddy by rotating around oneself. I have seen electric powered CL models, usually they carry the Lipo on board, but it is possible also to transmit power through 2 single core wires. 

CL will have longer lines then Whip and RTP.  Now if I were to fly indoor, it would only be the Whip or RTP. Whip means I would be in the centre of the flying circle and flying it all the way while RTP means I am positioned away from the circle.

Single tether flying

Now if I do a free flying model (an electric capacitor powered Farman Moustique comes to mind), I could insert a straightened piece of paper clip through the fuselage as a tether point. Then the other end of the line (can be any line, no need to conduct electricity and not care about electricity resistance of line) can be as long as the indoor venue allows, letting the model fly around a heavy base.  

Why?

• Basically it is just to tie a string to the wing or fuselage
• It will just fly under its own power around a pylon/base or you can hold on to the line if you wish.
• Tethered line can be long, short or anything in between. 
• No need for gears such as a pair of equal and exact lengths wires to pass electricity, wanting lower air resistance but also wishing minimal resistance to electricity flow. No transformer/adapter, no freewheeling contact points and matching pole, no controller (rheostat)
• Remove the tether point and model reverts to a free flight model.

Large field flyers

4 October 2022

There's a beach front with sprawling rough out front and across the road there's a large sandy field with clumps and scattered trees destined for future construction work. Both are unfenced and there's no flying restrictions.

Long and sleek flyer like a glider would be the best choice for air time and windy conditions. 

 

Rigid Parachute

 11 August 2022

OK, a RAM parachute is cool. Packs neatly into a small bundle, but needs careful rigging and launch to be successful. And I don't want to spend too much time. Visually, it is just an arc off a cylinder and has lines hanging the weight below.

Making the foil

1. Make a card template of an arc and hot wire cut out a foam former.
2. Cut 4 strips of 2mm foam sheet, curl them to get close to the foam former.
3. Glue 2 strips together, using the foam former to hold it to the arc shape. Do likewise for the remaining 2 strips. Now we have a curled leading edge and a curled trailing edge.
4. Cut strips of 2mm foam sheet to form the 'ribs' and glue them to the inside of the leading and trailing edges. A curled ladder frame is formed. Maybe 4 ribs is enough.
5. Glue tissue to the outside of the frame, use the tissue so that the grain is running fore-aft.   

Making the motor base

1. Just a rectangular piece to mount the receiver, battery and 2 motors.
2. 4 holes at the corners of the motor base will be the rigging points.

Rigging assembly

1. Make a starboard and a port pair of lift lines to pass through the leading holes of the motor plate. Each pair is adjustable by lengthening or shortening with a stopper.
2. Similarly, 2 identical pair of pull lines is done for the rear pair of lines and passed through the trailing holes of the motor plate. 

Cross struts

 21 July 2022

Simplicity=Repeatability.

Traditional layout construction is to lay out the longest and main structural parts (such as leading and trailing edges, upper and lower longerons), pinned out on the building board and then cut the struts to fit in between the outer frame.

There's usually a left and right side to be constructed and be identical.

The problems/difficulties:

• not a good fit
• not at identical position

Solve it by:

• Trace a working plan by positioning left and right fuselage together, typically the upper longerons are against each other, draw in the longerons and struts.
• Pin over long strips on the building board over the working plan. When pinning, leave enough space so that straight edge can be placed over the cut lines of the struts so that the straight edge can guide the guillotine cutter.
• Chop the struts, lay the longerons and glue in place.

The fit will be better and the struts will be in identical positions. It is easier to making accurate angle cuts. The number of cuts is the same. We may waste a few inches of strut material in total, but that's not a deal breaker.

Wing construction can be the same if there is no 'airfoil' ribs. For smallish model where curve plate airfoil is used, the ribs can be treated as struts in the fuselage example. Then need some water/template/rolling pin to get the flat plate to become a curved plate.

Pin strut material on board 

2P

 28 April 2022

Rectangular wings with dihedral, twin booms on wing tips to support rectangular tail which has the same plan view projected area with twin end fins. Twin push or pull motors on wings, connected to control unit on pod below the dihedral joint. Sliding battery below control unit.

Decalage of 3 degrees held by triangular snippets on wing tips so that twin booms are raised by 3 degrees.

May be functional but sure is ugly.

  

Herr Engineering's Piper Tri-Pacer

 23 February 2022

1. Cover tail surfaces. Use pins to pierce through for the rigging holes.
2. Cover bottom and top of wings, do not cover the centre section. The wing tips may not require separate pieces of tissue.
3. Cover bottom of fuselage in 2 pieces: rear piece is until the former for the main landing gear wires; then the front piece with a small hole to pass the nose gear's wire, trim and glue down to the main landing gear former, the nose former and then all round.
4. Cover the top of the fuselage from the nose former to the cockpit.
5. Cover the nose block. Remove the air-inlets, drill for propeller mount. For simplicity, it will be fixed 3 deg right and 3 deg down thrustline as per instruction. Not the best solution, but it is simple and I'll take the risk. Or don't cover the nose block because it will be time consuming. To cover such a compound curved nose piece will mean thin strips of tissue around the nose piece, sanded, then a flat (ish) tissue piece that has been cut to shape for the front end. If tissue covering is intended, do it before drilling and mounting the supplied brass pieces. For the reason that I doubt the supplied rubber will be so long as to climb the motor hook, I shall use the supplied motor hook.
6. Cover lifting struts
7. Cover the main landing gear fairings. Or substitute the balsa fairing with 2mm foam. The supplied balsa pieces are hard (heavy) and the design does not depend on them for any load bearing. Paper is not used because it distorts too easily.
8. Cover the cockpit from the inside, trim the window openings, cover the short columns.
9. Cover the sides of the fuselage.
10. Apply decals to tail.
11. Apply decals to fuselage.
12. Apply decals to wings.
13. Before the wing is glued to the fuselage, do I want the cockpit to be occupied? Tri-Pacer is a 4 seater, I don't know which is the pilot in front so just place 2? The rear bench can seat 2, but I think 1 is enough. Paper pilots/passengers can be cut from paper and glued to a stem between the middle longerons. Alternatively, the paper cutouts can be pasted on the side windows. Doing this will mean the side windows are to be glued on before the wing and front windshield are glued on.
14. Glue wing to fuselage (4 dots). At this point, the centre section  is bare, and the reason for not covering the bottom of the centre section is because we don't need tissue between 2 balsa surfaces.
15.  Mark CG on fuselage/wings juncture
16. Glue lifting struts: 1) chamfer both ends of each strut, 2) insert 1/2 staples (straight) to wing ends, full staples (V) to fuselage ends, 3) poke holes in wing for staples, 4) bend wing ends' staples to holes, 5) bend V staples to bottom of fuselage, 6) dots of UHU together. Really, why bother? Just chamfer and dot them together, any load bearing advantage is minimal when it is just glued to the lower longeron. The V-wire gives a good surface area for gluing though, but maybe a trapezoidal piece of tissue is a great alternative to cover and glue the lower ends of the pair of struts to the longeron, one on each side.
17. Glue horizontal tail to fuselage (2 dots on leading edge, one dot at trailing edge). As the tail is covered, before gluing, sand away the tissue from the bottom where the glue spots to the fuselage will be, this include the centre top spot where the vertical fin will be glued later.
18. Glue rear top stringer to fuselage. A support is needed on the bay infront of the tailplane because the vertical tail starts ahead of the horizontal tail.
19. Cover top of rear fuselage, over the horizontal tail.
20. Cover top of cockpit and wing centre section
21. Glue vertical tail to fuselage (dots at leading edge, trailing edge and bottom of rudder). Slit the top cover of rear fuselage. However, if the horizontal tail's trailing edge is to be capable of re-setting, then the vertical fin may have to be raised to allow clearance and so it can only be glued by the last fuselage post.
22. Glue cockpit struts (CA thread to V then UHU 3 dots)
23. Glue wind shield (UHU to wing, 2 bottom edge). The supplied plastic seems a bit too stiff, consider replacing if it does not form properly.
24. Glue side windows (dots to corners and rear). Can use thinner plastic bag material. This step can be done after the fuselage side is covered and probably before gluing on the wings.
25. Glue landing gear fairings to wire (3 dots), or preferably with a strip of tissue where it joins the longeron and a tiny dot on the wire (or an even smaller piece of tissue) so it can move independently when the landing gear wire flexes.
26. Install wheels (bend and cut)
27. rubber loop
28. Balance to marked CG. See below about solder wire.
29. Test glide
30. Trim horizontal tail (UHU can be softened with alcohol) 
31. Trim CG (stability)
32. Trim wing and vertical tail.
33. Mark new CG location out on the rib doubler for struts.
34. Test flight with partial rubber.
35. Trim thrustline (torque, add card stock to shim)
36. Trim wing (roll, gurney flap to left wing)
37. Trim vertical tail (yaw, gurney flap to direction of glide circle)
38. Mark final CG.
39. Add tail rigging, wheel rigging.
40. Use solder for weight adjustment. Plasticine is oily, will stain balsa and tissue and will dislodge, it can only be a temporary field adjustment. A piece of solder UHU glued to a tissue piece and coated in glue stick can be glued over a slit in the tissue of the model. Glue stick can be de-bonded with alcohol and it will allow correction.
41. Weights can be attached to nose wheel, inside nose piece (dig and glue), against the stringers (slit the tissue), tail post, wing tips.  
42. Masking tape can be used to mark the CG because it can be peeled away. The designed CG location is marked on the fuselage/wing juncture so that the wing can be glued back with them as the alignment marks. The final CG location can be marked with permanent marker and at the rib doubler at wing struts because the landing gear will obstruct direct balancing.  

1/16" balsa strips

18 February 2022

1/16" round strips

Start with 1/16" square strips. Even if they are not true squares, they should be fine. Here's an idea for a sanding jig for making 1/16" round strips simple. 

1. 2 ice cream sticks are placed side by side with a 1/8" gap.
2. A strip of sandpaper is glued across the ice cream sticks.
3. 1 piece of 1/16" square strip is glued to the outer edge of one ice cream stick (on the sandpaper).
4. 1 piece of 1/16" square strip is glued to the inner edge of the other ice cream stick (on the sandpaper).
5. The ice cream stick backed sandpaper strip is folded along the length to face each other with the square strip forming a 1/16" space.

The sanding action is by pulling and rotating slightly the 1/16" square strip to chamfer and round the corners of the strip. Since the sanding action is by the same grit of sandpaper, the sanding will be on 2 edges at a time and will stop sanding once it is reduced to the diameter of the 2 strip spacers.

1/20" balsa sheet

1/16" is 1/4 thicker than 1/20" (1.5mm vs 1.2mm). The difference is about 0.3mm. It shouldn't matter but if I really want to, for example, to make laminated wing tips, here's an idea for sanding 1/16" balsa sheet to 1/20", short lengths and widths only.

1. Glue lower grit (coarser) sandpaper to worksurface, higher grit sandpaper to sanding block.
2. The other option is not to use sandpaper on worksurface because its only purpose is to help hold the balsa in place without moving. 
3. Glue spacers to lower grit sandpaper (or worksurface).
4. Place 1/16" balsa sheet and sand lightly in one direction, pulling action. When starting on one side, it is ok to hold the balsa at one end and sand away from that end. Then the balsa is turned around so that the unsanded end can also be sanded. Then the other side of the balsa can be similarly sanded.

 

8 February 2022

Razor blades

Double edged razor blades are relatively cheap, thin (0.1mm?), sharp and has 2 cutting blades per piece.

On the minus side are the lack of a pointy tip, relatively flexible (if you need a stiff blade) and has to be handled very carefully to prevent injury.

This makes it suitable for chopping 1/16" square balsa sticks but not for cutting 1/16" thick balsa sheet.

Each blade comes wrapped in a folded piece of tissue and is inserted in a small paper envelope. I snapped the blade without removing the tissue or envelope, one end at a time with a small half round plier. I didn't find any bends at the snapped ends.

The other side of the cutting edge looks ragged but can be handled with a bit of care. The snapped blade can also be gripped with a cross-handle. The handle method is a bit better for sighting a vertical chop (and some rocking). I changed to this method for general chopping even though I almost completed most of the kit.

1/16" square strips

One thing I discovered about 1/16" square balsa strips supplied in the kit is that they may be cut from 1/16" sheet and some widths are slightly wider than 1/16". This is a problem and should be sanded down, preferably before using. In my case, it was used and it may be the reason for the slightly skewed fuselage.

Curve bends

Some curve bends were required in some strips. All I did is to wet with water and pressed between thumb, forefinger and middlefinger. Bend a bit more than the required curve to allow for some spring back when released.

Solvent: UHU and white glue

Water will soften and dissolve dried white glue, so will white glue itself. Alcohol appears to do it to a certain extent, but it wasn't conclusive. Alcohol is a great solvent to soften UHU All Purpose glue. 

UHU is more 'gap-filling' and appears much stronger than white glue.

Applying solvent allows glued pieces to be repositioned and once held in position, holds it new position without additional glue.

A dressmaker pin is a good white glue applicator. I squeezed a small blob of white glue on a sauce plate and used the pointy end of the pin to pick up some white glue to apply to the ends of balsa sticks. The sauce plate I use is also good for placing pieces of balsa which has their ends applied with glue to soak in and thicken. White glue washes off the sauce plate easily. I used a bit of transparent tape if I use UHU. 

24 January 2022

I started building Herr Engineering's Piper Tri-Pacer yesterday and here are what seems to work. The model is an 18" wing span flying scale model, stick and tissue type without preformed plastic and all the balsa pieces laser cut. 1/16" has to be precise but not to worry, it is not precision engineering as a little film of white glue will fill nicely. Making jigs, templates and specialised tools sounds great but is not an absolute. 

I started with this laser cut kit because I have no confidence of cutting balsa parts accurately. After I complete this model, I will have learned something from the process and gained some confidence to truly scratch build. My ultimate goal is to build a flyable peanut scale model airplane.

Building board

I didn't start the kit because I was looking for a suitable board.

• Essential for locking the pieces in the right places.
• I didn't build the model earlier because I couldn't decide on the material and size of the building board.
• I used an scrap piece from a 1" blue foam board, approximately 400mm long and 100mm wide. It is not big enough for the whole 18" wing which I prefer, but it covers more than the centre-section and one wing panel, and the whole fuselage also fit inside the board.

Blue foam is good with pins, there is no rubbery feel that I get with poking polystyrene. Blue foam is also structurally flat, firm and stiff and has no grain direction as it is relatively (to balsa) homogenous. 1" is light and I can grip it easily. The size is easy to handle. Normal transparent tape will tape nicely and it won't damage the blue foam surface when it is time to pull it off. The pin marks will remain but it does not interfere with future uses. Both sides are equally usable, although we only do one side at a time when building the structures, I can pin my structures on both sides when shrinking the tissue (haven't try yet). 

Taping the plan

• Make and cut photocopies of the plan. Use a pair of scissors to cut around the structure.
• Using 15mm plastic transparent tape, with handle (double back on itself), tape on the blue foam board across the joint areas of the structure plan. I have my tape handles either left of the structure or top of the structure.
• Continue with taping over all joints and end at the board beyond the structure. 
• On completion, pull the tape handles to peel away the cut plans from the blue foam building board.

The plastic transparent tape I used is normally for stationery purposes, it is smooth and thin, glue will not bond well to it and the structure can be easily prised off. It doesn't have gluey residue and provides a firm surface (supported by the firm blue foam) for chopping with razor blade. It is not loose like shrink wrap. 

Pinning and trimming sequence

• Cross pin the main parts. Choose pins for clothes making, not the notice board type, we want thin and long pins. 
• Straight pin the other laser cut parts to form the outline. This allows the pieces to be lifted vertically. 
• Identify the main balsa strips that runs straight and longest and trim to length before gluing and straight pin against the main parts. Check to ensure the outline fits snugly.
• Remove outline pieces and glue back in place.
• Let the glued outlined pieces dry thoroughly.
• Work on the biggest cross piece before the smaller ones.
• Do the cross piece against the main balsa strip, cut the free end to size, glue in place and then do the opposing cross piece.
• Complete the remainder cross pieces.

Straight pinning means pinning down vertically. It provides a lateral restraint, it locks the lateral position so if force is applied against it, thin balsa strip will not be displaced. It is also useful because balsa pieces can be lifted. If it is not feasible to have the pin directly oppose lateral forces, it is ok to pin on either or both sides of the force.

Diagonal or cross pinning means to pin diagonally or at a cross. It locks the piece in all direction.

against a butting force.

2 fuselage sides

• Remove all pins from the completed fuselage side.
• Lay a sheet of kitchen transparent shrink wrap over the fuselage side.
• Straight pin around the fuselage side.
• Cross pin the main pieces over the completed fuselage.
• Complete the rest of the pieces and balsa strips.
• It is easy to use the razor blade to chop the new strips.
• When dry, remove pin, peel off kitchen shrink wrap and prise away the original completed side from the plan.

The strips I have in the kit is not exactly 1/16" square. For the most part they are but inspect it closely and decide which is the 'up' side that gives 1/16" thickness. Sometimes I built with the sides, so the second fuselage side will have this strips thicker than 1/16". I intend to sand both sides after it is assembled into a box structure. On hindsight, I could sand the first completed side before building the second fuselage side. Never mind, it may not be precise but it is accurate enough that a bit of sanding will take care of it. I marked the inside of the second side so that I know which side is to be inside.

Double-edged razor blades

Advantages: very thin and sharp.

Disadvantages: flexible

• Each razor blades comes wrapped in a small piece of tissue inside a paper envelope.
• Grip at one end in the middle with a plier and snap against a flat surface.
• Do the same at the other end.
• Take one snapped piece out of the tissue and leave the other in the tissue and envelope. 
• Do only straight down chops. 1/16" balsa strips require only straight chops anyway. 

I didn't use NT cutter (utility cutter) or #11 scalpel. I didn't tape the razor blade or made any form of handle. Finger nails over the razor blade works.

Chopping 1/16" balsa strips

• Position the cutting edge over the 1/16" balsa strip to cut, somewhere in the middle third of the cutting edge, hold one end down and apply pressure on the other end follow by equal pressure on both ends to complete the chop.
• If it is a cross piece, lift the outer balsa strip to insert the cross piece balsa strip under and butt to the other side. If the outer balsa strip is a straight line, and it usually is, perform the chopping motion as before described using the inner side of the outer balsa strip as a guide. The razor is so thin that it is acceptable. The pin board will only be slightly damaged but it still function well.
• If a cross piece is towards laser cut outer pieces, mark with pencil and chop the cross piece at the chopping board. Sometimes the cut piece is too short, then it is relegated to the next length down.

White glue

• Squeeze a small blob of white glue in the middle of a small plate.
• A pin works as a glue applicator.
• A pin also works as a pick up tool for laser cut pieces because you can pierce the pieces. You leave them around the small plate if you are waiting for the glue to soak in a bit before using the pieces.
• As the white glue blob evaporates, it gets thicker. When it is too thick, wash and peel the glue blob off the plate. 
• White glue dries transparent.

Bending 1/16" balsa strip

• A cranked continuous strip is stronger, lighter and more accurate than with segment pieces.
• Use a small dish with a bit of tap water, and twirl the balsa strip between wet forefinger and thumb around the crank part.
• Hold one end against a wooden block and use the edge of the block to crank the strip slowly. Go slightly beyond the required angle.
• The cranked piece is then glued to the balsa structure with straight pins.
• Leave the 2 free ends long for trimming.
• For gentle curves (I didn't encounter this), wet the curved portion and a bit beyond, grip with the non-master forefinger, middle finger and thumb, pull slowly with the master hand at a slight angle, control the non-master hand's pressure.
• For tighter curves (I didn't encounter this), grip the curve portion between a hot solder tip and a surface, pull with master hand. Re-wet frequently.  

Mumbo Jumbo (Pre-Start)

 Sure, any cutting tool can do that, how accurate though? Yes, can be sanded off, again, we have to be careful or it is not accurate even though we took more time to sand it off. The end that was cut or sanded may not fit in exactly as the adjoining surfaces. It could be crooked, not straight; at the wrong angle, or tore off a bit. Why sand if it can be cut precisely?

Cutting precisely is not just using the utility cutter against a straight edge. Yes, it looks straight, but is the cut perpendicular? To cut with a slicing cutter we need the cutting edge to be at an angle towards the direction of cut and yet the cutter need to be held perpendicular when viewed from the side.

1/16" strips can be chopped off but utility cutter may crush the wood and still it may be chopped skewed or slanted.

A tool for chopping

A base is needed to rest the stick. A pivot is needed at the right height, depending on the chopping tool for chopping action, the force will be out to in. I think double razor blade snapped in half is the cheapest and most easily available chopping tool. Maybe a slicing action is better instead? A pair of guides will be needed to chop or slice with the cutting tool.

If all's required is to have the blade slide along a guide, then maybe:

• 2 pieces of 2"Lx1"Wx1/2"T square cut blocks. Daiso
• 1/16" scrap balsa piece, grain running parallel to block.
• Sandwich stick and scrap piece between 2 blocks.
• Use edges of blocks to guide slicing cut.

Or just hold the cutting tool vertically lor.

One ice cream stick, scrap balsa spacers. Lay stick in the slots, Place on cutting mat. Press with left forefinger over the stick and spacer. Cut using edge of ice cream stick as straight edge. Helps to hold the stick accurately. Or use Daiso blocks? If has a pivot for cutting arm? Arm can be ice cream stick with half blade superglued.

Don't snap the double edge razor blade?

A ply handle pivot to the base block with razor blade screwed on. Bring lever down and use it like a guillotine against the base block. 

Andrew Moorhouse

 16 February 2022

I found this designer of model airplanes on Outerzone.

His designs uses, in particular, his Luton Minor:

• laminated curved parts are from 1/32" thick strips, wetted and formed around cardboard templates and pinned to a plastic film covered building board to dry.
• 2 layers of 1/32" balsa sheet propeller blades, formed around a can, sanded while on can. When completed, they are glued to the 1/4"x1/4" propeller hub.
• 1/4"x1/4" balsa propeller hub and shaft, cross cut at ends, and uses tin plates with holes in the centre glued to the hub/shaft for bearing surfaces. Brass or alloy tube is also mentioned as an alternative.
• Uses nylon button nose. 
• His motor shaft has a square loop at the front so it can be winded with a winder. A small piece of wire acts as the catch that locks onto the loop while it is pivoted with a pin on the lighter side of the propeller. This pivoting catch disengages when the rubber tension is released and allows the propeller to become free-wheeling.

His plans are handwritten and complete patterns (including colour scheme) and printed parts are also pdf for printing. His kit consists of 1/16" and 1/32" sheets for strip wood, formers and ribs. Makes me want to find some 1/32" sheets. Very inspiring.

Brass or alloy tubes are mentioned as an alternative to tin plates. I think I will not because I may have to buy various tubing to get the appropriate size and I can't cut the ends squarely without lots of sanding. Even if I managed to find one that fits, I wouldn't use tubing as a button bearing replacement because it seems I will be relying on the fit and glue on the noseblock. A button bearing has a flange support to spread the compressive load to the fuselage frame. 

Tin plates are not so common now, I can still find them but aluminum cans are so easily at hand. I think it will be a good idea to substitute with small pieces of aluminum sheets cut from aluminum cans. I don't have his nylon thrust button, again, maybe I can substitute it with aluminum pieces as well. After all, while they may be thin and light, they will experience only minimal side forces and ought to be stiff enough to spread the compressive load from tensioned rubber to the fuselage structure. If 4 pcs of 1/16" can withstand the compressive load, I don't see why aluminum pieces can't when they are glued to a much thicker balsa base (nose block).

To make the 4 pieces (2 pairs) of aluminum bearing plates:

1. cut a strip off the side of an aluminum can with a pair of scissors/shears;
2. uncurl and flatten strip;
3. use a thumb tack to pierce the aluminum material against a wooden block; and
4. trim to shape and size with a pair of scissors/shears.
5. glue the 2 pairs to the solid balsa hub and noseblock, the burrs from the piercing faces each other so that no cleaning up on the outside is needed.  

Flight paths of rubber powered models

 15 February 2022

Initial torque of rubber is large and decreases rapidly, except for those very lightweight indoor see-through type of models which has a very long run. 

On power drive, the model flies in left circles. It is possible to fly in right circle during the power phase but that would mean lots of right thrust to overcome the torque.

I think I will have left circling powered flights.

When the power lessens or ceased, should the transition be continuing with left circles? I'd like that but I think my glide will be right circles. This presents a problem. If I trimmed the model to glide right, that also means that anything other than a right glide will be draggy, it will stall when it is flying straight for a short portion. There's always a straight portion in a S-flight path.

So, should I aim for a C flight or a S flight? 

After thinking it through, a S flight for torquey model to minimise power dives and a C flight for longer runs indoor type.

Features of C flight models, flights that yaws to fly left:

• long motor runs, low torque, big propellers
• longer left wing
• more wing incidence
• more right thrust
• Yawing flight: left rudder for left glide, wash-in at left wing, wash-out at right wing to keep wings level.

For my Herr Engineering's Tri Pacer, the instructions call for a S flight. I may have to re-read that. A modeller replied my query and said he had the same model and did left/left, i.e. a C-flight, with minimal adjustments.

Adjusting thrustline of rubber powered models

Following refers to those with removable balsa nose piece.

1. 2 brass/copper bushings glued to the front and rear of the nose piece, and a glass bead. (Herr Engineering's Piper Tri-Pacer)
2. 1 aluminium tubing glued through the nose piece. Use cup/flat washers or glass bead.
3. 2 small aluminium (from drink can) flat pieces, pierced in centre to pass through the motor shaft, with tabs to bite into nose piece. Glass bead or cup washer for bearing. 

Method 1 and 2 can only be made adjustable by shimming the whole nose block. When a hole is drilled and the bushing or tubing glued in, the angles of side and down thrust is fixed, relative to the nose block, so the nose block has to be shimmed to adjust the angles. It does leave a gap all round the nose block but maybe some paper glued on the nose piece will cover it up. It's not too bad then. Don't you think that having the propeller and the nose piece 'square' with each other looks nicer?

 Method 3 can allow thrustline adjustment if the balsa nose piece is drilled larger or slotted. We only need to prise off the rear piece and reposition. The pulling force is on the front piece, the rear piece only guides the motor shaft and withstand the side force. For neatness, the front piece need not have anchoring tabs, it may be glued to nose piece. Alternatively, front piece can also be made from plywood or other harder wood pieces so long as the glass bead won't pull through. As nose weight is usually needed anyway, can consider using thicker and heavier pieces. A spiked nut may be good for the front piece, the smallest available spiked nut is may be 3mm, but so long as the glass bead don't get pulled through, it can be used.  Maybe 2 spherical glass beads are better to reduce friction due to compression forces. The drawback? Maybe the look of the propeller hung skewed to the nose block.