WBP-1 Flying Plank; modifying Tian Sheng's TS800; RC WBP-1

Introduction

I wanted to build and fly a WBP-1 after I built a 'Red Butterfly'. I tried to chop up Tian Sheng's TS800 but that wasn't successful, the CG, while always there, was difficult to catch. Under the 'History' is, well, history, under 'RC WBP-1', the flyable WBP-1 using lightweight gear.

RC WBP-1

History

I have flown the Red Butterfly. I gave it to Wong and he told me the reason he is not flying it now is because he has to replace his motor.

The Red Butterfly is a 4 channel flying wing. I could do a light and small scale model of some real planes.


A few inspirations from the internet.
The first 3 photos shown here is of the Al Backstrom's WBP-1. A profile rubber scale was offered in Aeromodeller.

Flying wing is long in the tooth.

It can also be sleek looking.

Perhaps I could do a quick-to-built the original white WBP-1, also called the flying plank. RET control, 5mm foam with 2mm carbon rod leading edge glued and taped on, Guardian surgical tape hinge, 1" blue foam pod either with integral canopy or seperate moulded canopy, fixed fins, Turnigy 6A motor and ESC, GWS 5"x3" propellor, 2S 500mah battery, 2 Kingmax 3gm servos embedded in the wing just behind the leading edge for the elevons. Span not exceeding 25" (original is 25'). Below the plans offered in Aeromodeller.

 

Step by Step Construction

1. Begin with the wing. Mark out the wing's outline (25"x5" or 20"x4"), the elevon's hingeline (we will use spanwise strip elevon, not the partial outboard elevons) and the centre line of the wing onto 5mm foam board. This will be the lower surface of the wing.
2. Cut out the single piece wing. The cuts to be perpendicular, at 90 degrees to the board.
3. Glue the 10mm x 0.5mm carbon fibre strip to the top of the underside of the wing. Leave approximately 2mm of the strip exposed from the foam's leading edge. This 2mm ledge is to accept the 3mm carbon fibre rod.
4. Glue the 3mm diameter carbon fibre rod against the foam's leading and carbon fibre strip.
5. Shape the top surface of the foam's leading edge. One way is to sand lightly, another is to depress the foam with a hard and flat object.
6. Big gaps between the foam and rod or the rod and strip may be filleted in. Leave minor gaps alone as it will be taped over.
7. Place the wing assembly upside down to mark out the two servos location. All servos I used has the servo lead at the end where the rotary drive is located. The rotary drive is where the torque will be, so place it close to the leading edge, but no parts of the servo should clash with the carbon fibre strip. I don't cut my servos' mounting lugs, place the servo flat on the wing, rotary drive to the leading edge and facing outboard, mark around the servo including the lug position.
8. Cut out two holes for the servos. Slitting is sufficient to accomodate the servos' mounting lugs. The cuts to be perpendicular, at 90 degrees to the board. Dry fit the servos, do not glue in at this stage.
9. Place the wing upside down on the cutting mat. Orientate the wing vertically so that your master hand can draw the cutting knife towards yourself. I am a right hander, so I position the wing's trailing edge towards the left and the leading edge towards the right and I place my 12" ruler on the elevons.
10. Seperate the elevon strip from the rest of the wing with the cutting blade at approximately 45 degrees, blade resting against the bottom edge of the ruler which is right on the hingeline.
11. Flip over the elevon strip so the two 45 degrees edge cut meets with a 90 degrees  at a continuous point. The resulting V-cut is at the bottom of the wing.
12. Lift up both pieces, flip the elevon strip and place it against the upper surface of the wing so that the 45 degrees edges meet to form a 90 degrees ridge.
13. Apply Guardian's 1" surgical tape over this ridge. This is the underside of the continuous hinge.
14. Cut a rectangular piece of self-adhesive vinyl sticker. The vinyl should be larger than the rectangular wing with hinged elevon strip by about 1".
15. Apply sticker over the top surface of the hinged wing, wrapping around the leading edge.
16. Make the radius corner, cutting the sticker and foam. Trim the sticker.
17. Temporary cover the servos' opening on the underside of the wing to prevent dust and debris from sticking to the exposed sticky side of the vinyl sticker. The wing is placed aside and attention is now directed to the fuselage.
18. The fuselage shall comprise of two parts, an upper part and a lower part. Trace the complete fuselage shape onto 1" blue foam. Mark out also the wing's position and thickness. With a ruler placed on the lower line of the wing, extend the line to the nose of the fuselage. This line indicates the separation between the two parts of the fuselage. The separation line and wing slot lines are transferred over to the other side of the fuselage. There is no need to transfer the fuselage outline.
19. Cut along the fuselage outline.
20. Round the corners, including the canopy, the nose, and the turtledeck. The separation line and the wing's position and thickness should still be visible on both sides.
21. Cut out the wing slot. As the foam is 1" thick, and some accuracy is required, this is not as easy as cutting the 5mm foam. If I have mechanical means, such as a jig saw, I would use it now. Since I don't, I shall use a 6mm drill bit and drill the blue foam with my Ikea screwdriver/drill. Then using a NT cutter with a sawing motion, cut out the slot. The sighting advantage for having both sides having the same lines drawn is now realised. Leave the fuselage to one side and focus on making the motor assembly.
22.  On a piece of 2mm ply, mark out the outline, vertical centre line (not allowing any side thrust), points of the mounting holes, and the centre point of the firewall. The mounting holes shall be positioned in a 't' manner, and the motor wires will pass on either side of the lower part of the 't'.
23. Using a pair of shear, cut out the firewall.
24. Bond this firewall to a piece of 8-10 mm rubber foam. The markings should not be obscured. Trim the rubber foam to the outline shape of the firewall.
25. Drill the ply and rubber foam firewall. Use 3mm drill bit for the mounting holes, 6mm for the motor shaft clearance centre hole. The slot for the motor wires will be dealt with later.
26. Install four 2.5mm blind nuts on the ply side of the firewall.
27. Install the motor mount with four 2.5mm x 12mm long hexagonal bolts. Thread the motor wires and secure the motor on the motor mount with the set screws. Install the prop-saver on the motor shaft and band on the propellor. The motor mount is against the side of the firewall that has the rubber foam.
28. Take out the wing and the fuselage and mark where the firewall will be bonded to. I don't know how much of thrustline deviation to allow for, so it is set initially as zero-zero and flight testing will dictate how much is needed. A line for the firewall position is marked on the top surface of the wing. This is the line along the ply face. The set back required is when there is 10mm clearance measured between the propellor tips and the trailing edge. This clearance is for the compressibility of the rubber foam, the side thrust if necessary, and the forward flexing of the GWS 5"x3" propellor.
29. Slot the fuselage over the wing, if the fuselage is not flush with the trailing edge, lengthen the wing slot by sanding away the portion where the leading edge of the wing meets with the fuselage.
30. Transfer the firewall position line to the fuselage. Remove wing, keep it aside and extend the two ends of the line over and around the top of the fuselage.
31. Cut the fuselage along the transferred line and then the separation line. I now have a top half and a bottom half.
32.  Glue the firewall to the top half of the fuselage, the ply side towards the blue foam and the rubber foam faced motor side towards the rear. Remove motor, but leave the motor mount on and sand the junction of the firewall and top half to remove big bumps.
33. The motor mount is arranged with a pair of its arms vertically and the other, horizontally. There are two diagonally set-screws to hold the motor in placed, If the lower set-screw is on the left, the three motor wires will pass on the right, and vice-versa.
34. Plan and mark out, on the bottom of the fuselage top: the motor wires' route, the pocket to the ESC (whether horizontal, vertical, on edge or any angle in between), the routing to connect to the receiver and the battery. The motor wiring uses 2mm bullet connectors, make it so that the ESC, with its bullet connectors and the plug to the receiver, can be removed. If it is possible to have the receiver located in the fuselage top, so much better. Decision will be based on: having the ESC (and Receiver if possible) as far forward as possible; a neat and direct routing of wiring(even if the wires have to be doubled/tripled back on itself and be located in a pocket or a slot); ESC and receiver to be removable from tight fitting pocket/s or slot/s. It maybe possible that individual pockets can become a larger slot in the fuselage top; so long as it can be covered with vinyl sticker and is not too much out of shape, it is fine. There is not going to be much issue with weakening the fuselage top, leave at least 1/2" length of foam at the rear to provide buttress to the motor and it should be fine. Remember that the servo plugs of the two elevon servos will passed through the wing if the receiver is mounted on top and if the receiver is mounted on the bottom, the ESC plug will pass through the wing. If receiver will be located on the bottom, then a pocket/slot at the bottom fuselage piece will have to be planned.
35. Plan and mark out the vertical slot for the 2S500mah battery. It is located at the nose, as far forward as possible, leaving at least 1/4" foam in the corners and avoid the location of the nose gear. Check that the battery plug of the ESC is long enough; if the plug can be pulled through the slot and has sufficient length to be finger gripped, it is enough. In operation, after plugging in the battery to the ESC, the length of wire is doubled/tripled and stuffed into the slot. If the receiver is to be located at the underside of the wing, then the pocket/slot and groove for the receiver and its wires has to be marked out. 
36. Cut/saw/hollow the fuselage's various pockets, slots and openings. Trial fit of all components, temporary plug in two elevon servos and check that it functions properly. Also check that the motor rotates in correct direction.
37. If optional nose gear is desired, a wheel pocket is hollowed out from the lower fuselage half. The nose gear is built with a rectangle piece of 2mm ply, slotted to accept the wheel. The wheel is inserted into a L-bent wire and another bend locks the wheel in placed. Then the wheel assembly is glued on either to the top or bottom of the ply piece, and the nose gear glued to the fuselage. 
38. From the photographs, there is a single main wheel in the fuselage, but two main wheels are seen in the later photographs. If desired, fabricate the main gear following the steps for the nose gear. And if the twin-wheel main gear is desired, just modify the ply plate into two slots and add a pair of fairings.

Tiansheng TS800

TS800 Specification No motor required
Material: EPO Foam (Crash-resistant)
Length: 490mm
Wingspan: 600mm
Take-off Weight: 62 grams
Discard rear half the tail boom, insert central fin, install RC gear and a flying wing similar to the flying plank results.
Or cut off at trailing edge, install twin fins, motor and RC gear and a power model results.

Yesterday I toyed with the RC gear I have.
I have Kingmax 3.2g servos, Hitec Minima, and from a Walkera helicopter, a 1cell lipo mains charger and 3 numbers of 150mAh 1S lipo.
I googled if it is possible to operate the RC gear with only 1S, turns out it has been done but with larger capacity.
The lipos for the Walkera has a white connector and it cannot be plugged into the Minima.
I thought of soldering on a servo plug to the lipo, but then I noticed that the position of the sleeves is very close to that of the Minima's pins.
I don't know if the sleeves will mate with the pins.
I took one lipo, trim off the lug/tab nearest the black wire and discovered it can be plugged into the Minima.
The Minima was blinking red and green.
So I bind the Minima with my new 9X and it works!
Plugged in 2 Kingmax 3.2g servos, program the 9X and it works out ok.
The nose of the TS800 has a very small cross section, limited space to mount the receiver and battery.
I placed both lipo and Minima together to save space and make the cutting easier and minimal.
The nose of the TS800 is also very short and the 10cm servo plugs is long enough to be routed to the wing.
I need not use extension wires.
At first I thought I could glue on the canopy for strength and cut out grooves in the bottom to access the RC gear, but I think it is neater to have removable canopy.

Holding the airborne RC gear in my hand, I find it very light and compact.
If servo is 3.2g a piece, Minima is 4g, and the 150 mAh lipo is about 12g, total weight is only approximately 22.4g. I think it is perhaps the same weight of the stainless steel ball bearing nose weight that I removed from the canopy of the TS800.

So if the chopped up TS800 with new fin weighs 30g, and my hinges, horns, pushrods and tape weighs 10g, the total flying weight of the flying wing TS800 will be 62.4g, very close to the original TS800!

Some weight might be necessary to add to the model in order that the CG can fall within its allowable range, and this would be determined on the field, but the prospect is good indeed.