WLToys F929 F939 V911

31 October 2016 (PULL-PULL conversion)

Material:

• Plastic tubing from disposable cotton buds.
• Silicone tubing, 2mm?
• Paper clip
• Ice cream stick
• Superglue
• (Hot glue, pull strings)

Short length of ice cream stick, not exceeding 14mm, split into two unequal widths and superglued together in a cross fashion.
14mm length of plastic tubing superglued to the wider piece of ice cream stick.
Assemble two sets of pulleys, each from a short length of plastic tubing with two shorter lengths of tubing as stoppers.
Use short length of paper clip as a hinge, running throw both pulleys and centre tubing.

 View from the underside.

The twin pulley assembly can be mounted at the furthest end from the servo horns.

The twin pulley assembly can also be mounted next to the servo horns.

The twin pulley assembly can be hot glued in place so they can be removable.












Stringing the twin pulley assembly.

1. Length of pull string fixed at the rear control surface horn is threaded up through the furthest hole of the servo horn, round the horn, up through the nearest hole, round the horn again, down through the nearest hole, round the horn the third time, down through the furthest hole, around the pulley two times, add a dab of superglue to secure the string and back to the other side of the rear control surface horn.
2. Connect the pull string to the rear control surface horn, pass through a heat shrink sleeve, round the pulley twice, back to the rear control surface horn. Hook the z-bend of a short pushrod through the servo horn's hole, insert the straight end of the short pushrod through the sleeve. Heat/superglue to secure the pushrod against the pull string.

4 October 2016

If I epoxy a GWS type 5030 reverse propeller to fit over the WLToys propeller hub, I will have a pusher geared motor and prop. Two things to consider:

1. The shaft hole in the GWS propeller is smaller than the WLToys' propeller hub. I will have to drill a bigger hole and/or sand the shaft area. Or, could I thicken the white geared nylon shaft piece instead?
2. What could be a problem or a blessing, is that the GWS blade area is much bigger than the WLToys'. Trimming blade area and/or diameter is so not me!

I ordered fresh stock of receiver boards and the pinion motors a few weeks ago but they are still shown as Backorder on Banggood.

15 February 2016

100 pieces of 3mm diameter magnet is 5.9gram

The magnetic levitation experiment failed. The centre magnet is not needed because without it, the levitating magnet is still attracted to the centre position. Later found that others have tried and couldn't do it either (as far back as a century ago). The spinning action of the magnetic levitation toy is necessary for stability.



WLTOYS' F949 receiver block
Down elevator = right servo goes up








WLTOYS' F949 receiver block
Left aileron = left servo goes up












WLTOYS F929 F939 receiver block
Right rudder = right servo goes up
Down elevator = left servo goes up

WLTOYS	V911 Stick Direction	F929 F939	F949
Aileron	Left	NA	Left Servo Up
	Right	NA	Left Servo Down
Rudder	Left	Right Servo Down	NA
	Right	Right Servo Up	NA
Elevator	Push	Left Servo Down	Right Servo Down
	Pull	Left Servo Up	Right Servo Up

8 January 2016

Pull pull with single servo arm 

What if the bellcrank can be made light?

There's a 2mm slot between the two servos. The bellcrank support can be glued there. A slot at the other end of this support with enough room for two bellcranks to operate one atop the other and the axle glued across. The bellcranks will need to be accurate enough so they do not interfere with each other. One could be a thick bushing, the other would be a larger diameter spacer between the two bellcranks.

Pulley drums and spacers or bushings may be made by glueing coiled paper strips since it is so small and not much strength is required.

7 January 2016

Pull pull with single servo arm

This idea is to allow pull pull installation on WLToys' receiver board which has only single arm horns to the built in servos.

While it is possible to have single pushrods connected to bellcranks/levers and use that for pull pull, this is problematic: the slop, the complicity and the weight.

I came up with two methods of bypassing the bellcranks/levers and combining the ideas of these two methods, both servos of the WLToys' receiver board can be made to be used for pull pull installation with board mounted in either horizontal or vertical positions.

Method 1

1. With the receiver board mounted horizontally within a fuselage, the servo arm to be installed in the fore and aft orientation.
2. A pair of exit holes are made to the fuselage, they should be inlined with the servo horn's hole. There is some fore and aft movement when the horn is going through its paces, so the fuselage holes may positioned to be at the middle of this range, or, if that servo shall be used occationally only, at the line when the servo horn is at its mid position. There will alway be some kind of stretch and deformation so it is not a critical point. The exit holes are strengthened or bushed to have a radius towards the rear.
3. The pull strings are attached to the control horns and inserted through the fuselage exit holes and tied to the servo horn's hole.

Method 2

1. With the receiver board mounted vertically, the servo arms to be installed in the vertical orientation.
2. A pull string is attached to one control horn and the other pull string of the opposing control horn is threaded through an eyelet (or goes around a post) forward of the servo before returning to the same servo hole.

Hmm... They are all just variations of pulleys and loops aren't they? Even the bellcranks are also something like a limited pulley.

24 November 2015

I normally mount my receivers by gluing two/four strips of foam to it and then glue the foam to the model. With the Kirby Cadet, the servos are glued to the cutout. Today I thought of using Paulinda's Super Dough and polymer clay. They can be moulded to conform to the irregular receiver and then glued to both the receiver and model.
Nay, it is still easy to just glue foam strips, and lighter too. I haven't encountered any problem with the foam strips method.

16 November 2015

The 3 F929 939 receiver boards tested ok.

11 November 2015

Received 3 sets of geared prop, receiver board.

3 November 2015

A summary of mass:

• Weight of propeller, gear mount and motor is 7.6gm.
• Weight of receiver board is 5.2gm.
• 4 Channel airborne gear (200mah battery included) is 20.9gm.
• If only 3 channel, then 20.9-2.2 = 18.7gm.
• Therefore 200mah battery (V911 type) is 18.7-5.2-7.6 = 5.9gm

A summary of application:

• a failed Morane Saulnier (using a V911 type)
• a failed Yak 3
• a successful Yak 3 (larger)
• Cootie
• Chinook
• Kirby Cadet (using a burnt out esc receiver, F929 F939 type)

A summary of adaptation:

• a failed spinner made from Paulinda Superdough

5 May 2015

 3 sets of pinion geared motor, geared prop, spare prop, receiver all in one board.


















Propeller is 130mm, about 5". 2.2gm servo fits on the aileron port. Battery connector fits V911 batteries. 200mah in this case.









All 3 sets worked on my V911 transmitter.
Right aileron has the servo horn turn clockwise.
Right rudder has the servo horn turn anticlockwise.
Up elevator has the servo horn turn clockwise.

Weight of propeller, gear mount and motor is 7.6gm.




Weight of receiver board is 5.2gm.













4 Channel airborne gear (200mah battery included) is 20.9gm.

Junkers D1, Arup S2, Caproni Stipa

4 October 2016

An idea for a funfly version of a Stipa-Caproni: Flat sheets, large elevons and rudder (stubby wings) and it can do knife-edge and other 3D maneuvers?
Fuselage shall comprise 1 horizontal and 2 vertical pieces.
The top vertical piece includes the fin and the horizontal piece includes a pair of stubby wings and enlarged elevator.
The motor, receiver board, rudder servo and 1S battery are mounted to the horizontal piece.
The vertical pieces are braced to the horizontal piece with diagonal sheets.
Undercarriage structure comprises of a spar under the stubby wings, 2 struts cross at the bottom of the vertical piece which has a length of spar to spread the load. Heatshrink 2 soft wire pieces to the lower ends of the struts and glue on the wheel pants.

4 February 2016

How about a simple scale model of the Junkers D1? RET. Maybe I can print (laser print) stripes on paper, transfer stripes to coloured tissue, and use tissue as covering over foam model?
Simple sheet wings perhaps with single crank or rolled airfoil, or build up spar and cap strips over sheet wings?
Or maybe a cartoon scale type with deep fuselage (additional dihedral effect)?
Anyway, the dihedral, nose length and the tail areas have to be increased.



How about the Arup S2? Instead of 3 moving (+2 if tips are considered), let there be 2 elevons?
Sheet wing, foam fuselage bottom, paper fuselage top.





Maybe a ducted propeller scale model?
The rear tube of the Caproni Stipa shows to be parallel on the side view but tapered on the top view.
That could be represented by a foam tube, then slit V-cut at the top and bottom and join the edges together.
Instead of cones on cones or curved V cuts, how about just a simple straight tube, straight V-cuts for the tail end as described, then when that is done, 4 V-cuts in a X-manner at the nose and further division of V-cuts in between the previous V-cuts? Saves glue...
If cone on cone, instead of making all those calculation, just roll a rectangular piece of foam sheet into a cone, adjust, mark off, cut, glue.
I think RET would be simpler then 4-channel. The wings are so long, and they have bracing, so might as well give them dihedral.
As usual, increase fin/rudder and stabiliser/elevator.
Only thing is, if the WLToys propeller is to be inside the cowl, I think the model is going to be very big..., with wings beyond 30"? Make a cartoon version with stubby wings?