AliExpress

26 July 2024

Try not to buy and try to improvise?

Propeller can be made. Paperclip may not be strong, and a whole host of issues.

It may not be perfect but it will suffice; perfection is not my game.

25 July 2024

Haoye 6" propellers for rubber motor at AliExpress

Haoye's smallest is 6" and comes in 3 colours: Orange, Silver-Grey and Black. 

The hub has a free-wheel ramp and the shaft diameter is 1.5mm. (meaning anything like 1.2mm diameter shaft would be great?) Weight of the propeller is around 2.5grams. Costs: 10 pcs is SGD 3.08, shipping at SGD 2.70.

I think it is a great buy. Saves a lot of effort and it would be much more durable and consider that every model need some form of nose-weight anyway if you think the propeller is "too" heavy.

Gemini said it's good for 12"-18" model.

Further finds in AliExpress

Rubber Band Powered Airplane Winder Rubber Band Model Airplane Winder Cable Winder Competition Tool Belt Automatic Counting

SGD 16.92, shipping at SGD 13.53

10 Meters Power Rubber Band 1x2mm 1x3mm Elastic Band Parts for School DIY RC Airplane Model Training RC Fixed Wing Aircraft

10m 1x2mm at SGD 17.46, free shipping

All-in: SGD 3.08+2.70+16.92+13.53+17.46 = SGD 53.69

Just the prop and rubber: SGD 3.08+2.70+17.46 = SGD 23.24

Just the prop: SGD 3.08+2.70 = SGD 5.78

Start experimenting with making models that uses the propellers. Then see if office rubber bands work. Then change the rubber to see if it is better. Then buy a winder and see if it is better.

Gemini seems to agree:

Recommendations:

• Start with just the propeller (or propeller & rubber bands if you're unsure about office bands).
• Experiment with building models that use the propeller.
• See if office rubber bands work for propulsion.
• If office bands aren't effective, try the different sizes you bought to see if there's an improvement.
• Only then consider buying the winder if manual winding becomes a hassle.

This way, you can gradually invest in your rubber band powered airplane project and see what works best before spending a lot on a winder.

Could also look for other things at AliExpress. Plywood, tubings, RC gear, glue, ptfe sheets to make bearings, air compressor?

micro rc gear

23 July 2024

Available for gym indoor flyer.

Not exactly equivalent, for pack includes charger and transmitter (about USD 18, retailing individually at USD 35.96).

Let's say 5g and an AUW of 10g. 412 thrust is 6-7.2g.

Gemini said it would be challenging.

23 July 2024

Good for general sport plane, not as gym flyer.

The brushed electronic pack included 2 servos, 1 battery, 1 charger.

I will save 1/3 by getting the brushed electronic set?

No appreciable weight savings with AIO receiver. Maybe the separate servos will actually be 20g and so the difference is only 3g.

If AUW is 40g (only 2 servos and using 260mah), then the motor thrust is 1.5 times. The thrust is powerful, not enough for 3D which would require at least 2 times.  

Here's a spectrum to consider:

• 1.0 - 1.2: Ideal for beginners in precision aerobatics, offering good control and longer flight times.
• 1.2 - 1.5: A sweet spot for many precision aerobatic planes, balancing agility with power for maneuvers.
• 1.5+: Excellent for experienced pilots who prioritize fast maneuvers and recovery from mistakes, but might sacrifice some flight time.

Anyway, flying aerobatic full-house will require 3 servos, and I can't imagine a single puny servo to work large control surfaces.

From MinimuRC, the product specifications:

High Speed 816 Brushed Motor Set, Motor+gearbox+prop, with 1.27 plug

USD 7.48

6.37g, 107mm prop, 1.5mm shaft dia, 816 brushed motor with 1.27 plug, 3.7-4.2v, maximum 67g thrust

Brushed Electrics Pack

USD33.29

receiver, 2 servos, 260mah, charger

3rd Generation Micro 5CH receiver with battery & motor sockets (for 1S aircraft)

USD 34.98

1g weight, 1.0 JST connector, 3.7v, 

5CH AIO receiver

USD 42.98

3.2g, 24x24, 5 channels, 3.7v, 1.0 jst

1.7 gram micro servo

USD 6.33

1.0 jst, wire length 110mm

3.7v 60mah Lipo

USD5.98

27x13x4 excluding plug, 1.25mm JST, 1.55g

180mah 3.7v 30c Lipo

USD4.98

3.7-4.2v, 180mAh, 30C, 4.66g, 45.7*12.5mm, 1.25mm JST (Molex 1.25)

3.85-4.35v 260mah 20c Lipo

USD 4.98

1.25jst

19 July 2024

Magnetic actuators, <10gm, gym flyer, 220mm wingspan

Minimum RC?

Transmitter, receiver, motor+prop, actuators, 60mah lipo, low charger =$100?

7 June 2024

Differential thrust, use RC quadcopters? 

6 June 2024

Differential thrust is the lightest, the less powerful motors and gear can be used for indoor flyers.

Being able to move the rudder, elevator and ailerons gives much more control, but they are a greater investment then differential thrust rc planes. We have had experience with 8.5mm geared motor driven RC plane, we flew that outdoor and they are just like the normal RC planes that we know, except they are shorter range, smaller, lower performance, and more susceptible to wind and gusts. 

Everybody likes the idea of a living room flyer, but that's where things get tougher.

Basically they are the backyard and gym types.

Backyard flyers AUW 50 gm. Uses servos, geared or direct brushed 7mm dia motors for backyard. 1s 150mah-260mah, will need pushrods.

Gym flyers AUW 10 gm. Uses magnetic actuators, geared or direct brushed 4mm dia motors for Gyms indoors. 1s 50mah-100mah, may not need any pushrods, you only get to make perhaps 300mm wingspan models which doesn't fly slow.

Receiver is about the same weight, but the 0.22gm per actuator vs. 1.7gm per servo is obvious and so are the motor, battery.

Even after the use of connectors, actuator's fine wires are short and can break easily and the battery dies easily.

For durability and easier installation, use servos type.

The wing loading has to be kept down for indoor flyers. 1gm per sq inch may sound to be very light, especially if you have been thinking about 8 oz/sq ft floater with "normal" RC gear, and it won't handle gusts well, but the flying speed is still fast for tight spaces. e.g. 50gm auw for 50 sq inches is too fast for small indoor venue or relaxed flying. Half the wing loading and half the flying speed.

1.27 2 pin motor

1.25 jst battery

1.00 jst servo

Hang Gliders

19 July 2024

Build a micro hang-glider, use this opportunity to discover what works, and consider powering and controlling after the concept works.

The structure of the small flying wing comprises of only the leading edge and at least 3 ribs. To have the CG at the correct location (low and forward), a gondola is glued to the central rib.

Rogallo Sail?

1 July 2024

There are a few sports which involves the use of some form of a kite. 

My recollection of windsurfing is a person standing on a surfboard which has a keel, a fin and a wing sail. The wing sail has a wishbone like spreader to tension the fabric sail against the mast.

I have seen some kites which uses inflated leading edge and 3 ribs that are held without fixing to the board. They are creative because these kites/wing foil floats on water, unless the windsurf sail.

Isn't that just like a rogallo wing with ribs (batten)!

21 June 2024

A rogallo wing with ribs (batten)

The wing has a balsa leading edge from 1/16" thick x 1/2" wide sheet.

Prepare the ribs by making as many triangular wedges with their peaks rounded off.

Glue these ribs below the leading edge.

Cover the wing structure, attaching the tissue to the leading edge and gluing it on the ribs.

Trim the entire covered structure, cutting out the tissue and protruding ribs so that the planform can have a graceful curve on the trail end. This will result in some washout which help stability.

Sand the root panel to the dihedral angle, if the ribs are too thin and the root rib was not positioned slanted for the dihedral, we can just glue balsa end plate to each wing root and sand for dihedral

Glue the wing panels together.

22 March 2024

Rogallo Wing Advantages:

• Simplicity: Easy to build and lightweight, perfect for low wing loading models.
• Inherent Stability: The curved profile creates lift and some inherent pitch stability without separate horizontal stabilizers (in low wind conditions).
• Low Stall Speed: Works well with low wing loading models that need low airspeed to stay aloft.

Rogallo Wing Disadvantages (Reduced Washout):

• Decreased Stability: Reducing washout (wing twist) improves lift but decreases inherent pitch and directional stability.

Adding Stabilizers:

• Improves Control: Vertical and horizontal stabilizers (fin and rudder) compensate for the reduced stability from washout reduction.
• Enhanced Maneuverability: Allows for better control over the model's pitch and yaw (turning).

Considerations:

• Size and Weight: Keep stabilizers lightweight to maintain the low wing loading advantage.
• Balance: Carefully balance the model with the added stabilizers to ensure proper flight characteristics.
• Wind Conditions: In higher winds, additional stabilizers become even more important for maintaining control.

Overall, using a Rogallo wing with added stabilizers for a low wing loading model is a viable option. It offers a good balance between simplicity, lift, and control.

Here are some additional points to consider:

• Experiment with Washout: You can experiment with different levels of washout to find the optimal balance between lift and stability for your specific model.
• Control System Design: The control system for the rudder and elevator needs to be lightweight and efficient to minimize drag.
• Flying Practice: Models with Rogallo wings and additional stabilizers can still be tricky to fly at first. Be prepared to practice and adjust the control throws for smooth flight.

You could probably do up a model this way but it would need much convincing if I were to do a scale subject. For one, if CF rods were used as the leading edge (and only spar) of the rogallo wing, for lightness, it would bend under the strain of the sail and the trailing edge of the sail would also be ballooning. It wouldn't look right.  

_________________________________________________________

Rogallo rc, need find geared motor, WLToys, other mini receiver

FF with stick or foam, solder capacitor

Sniffi glider, 2mm depron glider

Late 280: seaplane, plank/delta

Twin motors: from KF606, E010, E009; for parachute, twin planes, biplane, extended wing

1/2 gram receiver: solder thin lacquered wires?

Rogallo using drinking straws for spars?

Obviously only suited to AUW of only about 10g?

And is it acceptable to have less sweepback? I think so, let's say we only want sweepback of 20degrees. 180degrees -2 times 20degrees is 140 degrees. Give maybe 10% for the rogallo sail, so that makes it 150 degrees for the sail foil. Maybe it is better to cut out some at the keel and leave some at the tips.

Over A3 sheet of paper, draw the sail's dimensions. Draw parallel lines so that keel and spars can be wrapped by sail.

Flatten a piece of drinking straw, make a strip of cardboard which has the width slightly wider than the flattened width of drinking straw. The centre keel may alternately be inserted through alternating slits in the sail. To make the pockets for the spars, place the cardboard strip along a leading edge and then fold the outside and stick the sail foil together with double sided tape. Withdraw the cardboard strip and a pocket is formed neatly.

Paper Rogallo?

Again, targeted for AUW of only about 10g.

A4 paper can make a mini rogallo sail. The leading edge will not exceeding the breadth of the paper. The maximum wingspan is around the length of the paper and area around 3/4 of the paper's area. A paper airplane's or dart's wing's strength relies on single folded paper. Maybe a paper rogallo of single layer but with strengthening on lines and edges by folding once and with the curving foil is strong and rigid enough.

 Cut a square from A4 with a diagonal crease. The leading edges have 5mm overlap glued. Mark centre of leading edge for strut support. Extend a line between the 2 strut support locations. Where the line intersects with the keel (that's the diagonal crease mark in the beginning), is the central column support location, 5mm either side are the central strut support location and this gives additional dihedral to the rogallo.

Pierce the 4 holes, insert a thin bamboo stick and bring in the leading edges slightly so that the paper is curled. The rogallo is now basically done except for CG adjustment and the addition of central strut structure for the RC stuff.

A 3 ply foam gondola can be constructed to house the RC gear and the 1s cell. The center laminate is cut from 5mm foam to hold the RC gear and 1s cell. The outer laminates closes the RC gear and 1s cell and can be thinner foam.

2 pieces of 2mm foam strips can be the hanging central struts, placed at a Vee to each side of the gondola. At the top of each end is a hole where the thin bamboo stick passes through. The 2 motors are glued to the struts. At this point, the whole gondola and V struts will pivot around the thin bamboo stick. A 3rd strut is needed to set the gondola at the correct angle to the keel of the rogallo.

If the paper rogallo crumples too easily at the nose, additional thin bamboo stick can be inserted in the keel.

I experimented with making a simplified rogallo from an A4 sheet of paper:

• too flimsy with paper alone, the folded leading edges are too weak to maintain form.
• it is easier to fold than to curl, When I thought about it, two cones can be represented by 2 folded cones, isn't that the Dart280 idea?

So the conclusion is, without the supporting frame, paper itself is too flimsy, CG was definitely wrong and the flying speed required for a glide was apparently fast which isn't what I'm after. If supporting frame is required, then might as well use lighter sail material?