Trimming Flights
Nothing extraordinary, I slipped the 2s500mah battery rearwards and it's fine. I didn't bothered myself to adjust the down and side thrust lines.
It looks slow when flying into wind. This will be last entry and here are the cropped snapshots.
Completing after Test Fly
The flights tell me that there is sufficient power from the Turnigy 2204-14 1700kv spinning 7035 propellor on 2S 500mah. It is flyable but not slow enough, after removing the 20gm noseweight I think it is still slightly noseheavy. With maximum up elevator trim, the model points upwards and requires full throttle to fly at approximately level altitude, I would think the CG is around there and would try a 8" prop next time.
Before the rigging, I did the pilot. The pilot's head and hands is from a clay that hardens after baking in oven. I got the clay online from
www.banggood.com , cheaper than going to ArtFriend. The body arms and legs are from ArtFriend, a softish white bouncy substance called Super Dough (Paulinda). It cannot be detailed like a firm clay but can make folds and creases to the outer surfaces.
Do not put Super Dough in oven!
Starting with a bald head.
Then I added hair and made his pair of hands, baked them and joined all up in Super Dough.
Then I added the wings' rigging using thin nylon monofilament thread. The rigging is close to the real arrangement and the thread is practically invisible. I made hooks and such from soft wire to tie the thread and then used a black permanent marker to accentuate the rigging wires.
I folded pre-printed paper and glued on to the undercarriage wire to give the appearance of timber. It would be easier I think, if I attached the pre-printed paper to the main 'U' wires first, then insert the soft wire for the upper and lower cross bars, cover them with pre-printed paper, and finally do up the riggings. This way I would not need to make loops for the rigging at the lower cross bar and the timber look will extend to the bottom, looking neater. I did the hook design and installed above the lower axle because I was afraid that some lower rigging would bind the wheels.
For the side frames that were evident in photos of the real plane, pre-printed paper was glued to card, cut out, glued on.
I cut out and rolled two cones from pre-printed paper and glued them to the wheels, covering the ply disc and aluminium tubing.
Two yakult's drinking straw were heat bent, slitted and glued to the bottom of the "U" undercarriage wire, then with the same black marker pen, coloured to represent the skids of the real thing.
The rest of the framework at the nose were painted with the black permanent marker. This includes the firewall as far as I can reach it.
Components should be pre-coloured as much as possible, e.g. firewall painted installing the motor, framework painted before the cardboard side frames, skids painted before gluing to undercarriage, etc.
The model still lacks rigging between the nose and wing, the stabilisers, the cross bars, and some representation of the exposed portion of the 7 cylinders engine.
Test Fly
After flying the WBP-1, I was thinking the Blackburn Monoplane might be too heavy. Instead of completing the model with rigging, pilot and painting, I decided to test fly the model, even though it wasn't completed.
I added the pushrods and wheels. I could remove the entire undercarriage, but I do not fancy belly landing this model and the model would appear wierd.
Mass was approximately 210 gm, but the balance is at beyond 1/3 of chord so I added 10gm leadweight to the nose. The propeller is a 7035.
A Turnigy 2204-14 turn is installed. With a 2S500mah battery at storage voltage, the model could not hang from the 7035 propellor.
From HobbyKing:
Model: A2204-14
Cells: 2-3
Kv: 1450rpm/V
Maxx Eff: 74%
No load Curr. .3A
Max Current: 7.5A
Weight: 19g
Int. Resistance: 550mh
Dimensions: 27.6 x 11.5mm
Recomended Model: (3D 220g or less)
Recomended prop: 8040/2S or 7035/3S
This is similar to the AXi 2203/52 or 2204/54
Use a 10A
ESC with this motor.
It should be sprightly.
History
This is how I would tackle this project.
From
www.outerzone.co.uk download the peanut plan of a Blackburn Monoplane (Model Builder October 1975).
I wish to use my existing 2S500mAh batteries, Turnigy 2205 motor driving an 8" propeller and micro servos. The model is 4 channels (2 ailerons, rudder, elevator, throttle).
The pdf is upsized with a photocopier about twice.
The amount of enlarging depends on how many tiled pieces of A3, I don't like to tape too many A3 sheets but want something close to 26" wingspan.
This turns out to be 190% on four A3 sheets.
Physical work done with, comes the dreaming phase, i.e. the Design Phase.
It seems logical to lay the battery flat on the fuselage top, i.e. on top of the top longerons concealed by plastic/card/balsa conical cover. To suit my 2S500mAh batteries, the fuselage has to be widen slightly. It has to be wide enough to seat and strap the battery in placed. This means a new set of formers to be created.
I have experienced one too many dangling battery to have my flight battery unsecured, I shall strap it down by passing a loop of double sided Velcro like strap (or other means, maybe a band of elastic?) through the top longeron position. This means the fuselage has to be wide enough to provide the necessary clearance or else the top cover won't hold.
Meantime, I have to search for this illusive double sided hook strap. If I can't find it, then a loop of elastic band such as those for making clothes should be ok.
Horizontal Crutch
A 1/8" balsa horizontal crutch shall take the place of the two longerons and cross members for simplicity and ease. The top profile of the fuselage, including the bulging nose cowling, shall be drawn onto a 1/8" balsa sheet. A centerline is drawn, the new width marked out and formers position lines drawn perpendicular to the centre line, first to mark out the lower fuselage and then to transfer the lines around the balsa to mark out the top formers positions.
Firewall
A short length of 10mmx 10mm aluminium angle will be epoxied (hotglue does not work well on ply surfaces) onto the back of a ply firewall and the other flange will be bent opened slightly, ca 3 degrees to provide downthrust. (or closed, depending on 2 things, it's position against the firewall and whether it is mounted to the top or the bottom of the horizontal crutch). The Turnigy motor will be screwed to the plywood with some spacers (because of the motor wires). And then this assembly will be epoxied to the horizontal crutch after the cowling is made and then the motor screwed in. Most likely, the horizontal flange will be epoxied to the undercarriage hard point, and the vertical flange pointing up.
Undercarriage
Fabricate from 3mm aluminium tubing two pieces of axle fixing device. For each piece, start by grinding down on one side of the tubing to approximately 2/3 of the way.
Cut off the tubing piece about 6mm each end from the slotted tubing.
Bend tubing at 90 degrees onto itself, forming a "U" shape.
Coax the slot with needle nose plier so that the two ends are brought in again and forms an omega shape.
Tape, with masking tape, two lengths of 1.5mm piano wire.
Slid an axle fixing device into each wire.
Tape again so that the axle fixing device is in the middle of each wire.
Hold the two lengths of 1.5mm piano wire in a plier and bend them to a 'U' shape.
Unbend the 'U' to the angles shown on the side view.
Tape the pairs of free ends, using masking tape, with one edge at the point where the next bend shall occur.
Slit the tape between the two wires so that the wires separate but each has a tape marking on each end.
With the side jaw of the plier at tape's edge, bend the ends at ninety degrees.
Cut off excess wire from the ends, leaving 1/4" which is sufficient and remove all tape.
Unbend the ends to the angles shown on the front view.
The two wires should be more or less symmetrical and the legs are slightly longer, which is more or less correct given that the splaying out requires slightly longer legs in the first place.
Other wire pieces are then bent and cut to shape.
The two top separator pieces is soldered and the remaining is soldered during the final assembly stage.
An alternative is to use heat shrink tubing, it ought to be sufficient though not as robust.
Lower Fuselage
Make the undercarriage hard point and ply doubler from 2mm ply.
The width of the ply doubler is 1/4" smaller than the horizontal crutch to accommodate the foremost formers.
Two lengths of 3mm aluminium tubing to the width of the ply doubler is bound and epoxied in placed to receive the undercarriage primary wires.
Offer the undercarriage primary wires to the tubing before the tubing is epoxied in place.
Two servos (rudder and elevator) is glued after the rear tubing. Leave to one side.
The dimensions of the formers for the lower fuselage shall be measured against both the horizontal crutch and the side view of the plan and drawn onto 1/16" balsa sheet. The formers to be glued perpendicular to the horizontal crutch.
For the foremost formers along the ply doubler, they are constructed of 1/8" square strips and made into triangles (an inverted "A"). These A frames are necessary to accommodate the ESC, receiver and various wires.
The lower fuselage is nearly completed after the single bottom longeron is glued to the apex of each triangle and the assembly sanded down.
Glue the two pieces of paper/cardboard to the lower fuselage. To reinforce the servo spindle output hole, paper reinforcing rings are affixed on the inside of the rear paper/cardboard. Trim the paper/cardboard, locate the holes for the undercarriage primary wires and the lower fuselage is complete.
Upper Fuselage
Check that the position lines of the formers are complete on the horizontal crutch of the lower fuselage.
Prepare a set of the rear formers for the rear turtle deck from 1/16" sheet, mark the stringers position.
Glue the first former to the rear of the cockpit opening perpendicularly to the lower fuselage.
To make the removable battery hatch, either,
- make a set of front formers with side rails and tack glue the assembly in position, cover it with pieces of paper/cardboard, slit it free and install locating magnets to secure in position, or
- to pull a pvc sheet to shape with a male mould from blue foam, and install locating magnets.
In either of the above, a former at the king post position has to be glued to the hatch.
Glue the remaining rear formers perpendicularly on the horizontal crutch and then the 5 stringers. Sand down, and the turtle deck is complete.
Epoxy the firewall assembly to the ply doubler and the entire fuselage is ready for covering.
Perhaps a pvc sheet can be pulled over a mould to form the front cowl and deck? The resulting one piece plastic will be easy to place and replace in the field while changing batteries. Concerns are at the front where the plastic has to be pulled tightly, the pinched area where the cowl meets the deck and the lowered decking where it meets the rear turtledeck.
An alternative is to shape front cowl from blue foam, and pre-printed paper for front decking.
Covering the Fuselage
The fuselage is covered with pieces of tracing paper, except for the removable battery hatch which is ready to receive finish.
Dissolve white foam with thinner and apply solution to fuselage to prepare the balsa, paper/cardboard, tissue surfaces.
Spray the fuselage with colour of cream (slight yellowish white?).
Paint in the wooden features, i.e. the exposed balsa and paper/cardboard and the cockpit area, including the back rest.
The battery hatch may be finished with shiny silver/aluminium vinyl sheet or sprayed silver. King post glued on after painting at the final assembly stage.
Wing and Tail Feathers
Wings maybe built up from balsa or cut and sanded from compressed foam sheet.
Wings may be of 1/16" ribs, twin 1/8" balsa spars if 3/4 depth (to have unobstructed top surface), 1/8" trailing edge, 1/4" leading edge, 1/8" wing tips.
A more involved built up:
- Ribs may be separated into upper and lower ribs, lower ribs being 1/16" sq, upper ribs being lamination of two 1/16" sq. In this case, the trailing edge would be either 1/16" or 3/16" thick, depending how the laminated rib is glued on to the trailing edge and lower rib. The wing tips follow the same thickness. Taper the strip or tips to 1/16" before use. There is no spar to obstruct the top and bottom surfaces.
Add the aileron servos, lead the servos wire to the centre of the wing.
Cover wing with tracing paper, I may use glue stick or UHU glue.
Seal the tracing paper with the solution of white foam and thinner.
Spray the wing with the same colour as the fuselage.
Add post-shading details.
Install horns and linkages.
The wing is not removable, it is glued to the fuselage.
The horizontal stabilizer and elevators is constructed out of balsa and carbon fibre rods.
- My carbon rod is ca 2.5mm, I will use it as the hinge edge (and trailing edge) on the fixed stabilizer and a small length as torque rod to the horizontal elevators.
- The leading edges, sides and trailing edges could be made from 1/16"x1/4", but I think I will make them from 1/8"x1/4" strips, with each strip planed to a tapered section before use.
- The internal cross struts to be 1/8"x1/8" strips (could use 1/16"x1/8").
- The leading edge of elevators to be 1/8"x1/4", slotted for torque joiner.
- Pin the span-wise elements (spars, hinge, leading edge of elevators, trailing edge) on the plan. Cut the chord-wise elements and glue to the span-wise elements. Align the leading edges, trim the span-wise elements and glue to the span-wise elements. Glue the diagonal elements. Remove from plan, cut the centre piece out of the trailing edge, and trim all edges.
- Hinging will have to be figure 8 threading after covering but before painting.
The vertical stabilizer and rudder is constructed out of balsa.
- The same size of strips as the horizontal stabilizer to be used for the leading edge, sides and trailing edge; either 1/16" x 1/4" or 1/8" x 1/4".
Follow the same covering, sealing and painting process.
Glue the vertical fin perpendicular to the horizontal stabilizer.
The tail is not removable, it is glued to the fuselage.
Install horns and linkages.
Final Assembly
Glue the ESC to the underside of the ply doubler in the open framed structure.
Connect up the receiver and stow it in the paper/cardboard covered A frame space to the rear of the ESC.
Spring open the undercarriage to guide it over the tubing holes, release and solder the remaining wires.
Solder the inner retaining washers, slide the wheels in, solder the external retaining washers.
Make up and glue the landing gear struts to the undercarriage wires.
Screw the motor in place.
Slit an aperture on the battery hatch at the king post position, insert the finished King Post from the insider of the hatch and glue the King Post to the balsa former.
Tack glue the fake rigging wires, they will probably be ripped off in flight and handling anyway.
How I did mine, two at a time
I am doing two at a time because although it will take a bit longer, the time taken will not be twice as long, I get more practice, the additional airframe can either be a spare or a gift.
Horizontal Crutch, lower fuselage and upper fuselage
I have found some thin double-sided hook&loop strips and they should not require widening of the fuselage if used for battery strap. These straps will not require slots in the horizontal crutch, a dab of hot glue should be ok for the light battery and so much the better for doing less.
Measured from plan, the fuselage is ca 1.5".
I cut a 2mm ply sheet to 1.5" wide for the ply doublers to the two models, and from two 18"x2"x1/8" wide balsa sheets, the horizontal crutch for the two models.
A technical protractor set square was put to good use to mark the perpendicular lines (position lines of formers) and the 2 degrees firewall offset on the lower side of the ply doubler and both sides of the horizontal crutch. It is not necessary to mark all the lower lines on the horizontal crutch because any lines on the forward half will be covered by ply doubler.
The plan view of the model was marked on the top side and the horizontal crutch cut out.
White glue was spread thinly to the mating surfaces of both ply and balsa and with spring clamps (clothes peg), they were adjusted to final positions and left aside to dry. Both ply reinforced horizontal crutch were glued one after the other, but clamped together to dry, since they were identical. The top sides mated each other.
Offcuts from the balsa sheets for the horizontal crutch were ideal for the pair of formers at the front cowling position. These were cut out with 2 degrees right thrust and glued to the balsa crutches. They were cut into triangular shapes without the front cowling radius, as they shall be finally sanded to the correct shape after the nose ring former is glued in placed.
Progress photograph:
The position lines for formers indicates the front of the formers. There is no position line for former 9B, the rear if the last former would simply be placed along the end of the horizontal crutch.
Undercarriage
I bent the undercarriage primary wires from what piano wire I had. The chosen wire was a bit thicker than 1/16" and closer to 2mm. The pair of U-shaped wires that I bent were identical in shape, but the wire was too strong for my plier cutter. I couldn't cut the wire, so they were abandoned because I think it would be easier (for me with existing tools) if I cut them from 1mm or less wires. 1mm is too thin, but I think they can be made functional and durable if I stiffen the undercarriage by heat shrinking over carbon, ply or even balsa strips.
Horizontal Stabilizer and Elevators
- Start with taping span-wise, scotch tape over the plan, covering the gluing areas. With the plan prepared, position over cork board.
- Pin two lengths of 2.5mm carbon rods over the plan. These are the hinge edges.
- Pin a single 1/8" x 1/4", over-length, over the trailing edges of the elevators. The centre piece will be cut out later to have 2 elevator halves.
- Turning towards the leading edges, trim a slot from 1/8" x 1/4" to receive the carbon rods. Match the angle where the leading edge joins the trailing edge of the elevators. Glue and pin over plan.
- Trim the two 1/8" square spars to fit the leading edges. Glue and pin over plan.
- Fit the remaining elevator edges, the lengthwise and diagonal braces. Glue and pin over plan.
- When the glue has dried, lift the resulting triangle shaped tail feathers from plan.
Wing
From a 4" wide 1/16" balsa sheet, I drew parallel lines 3mm apart, cut them to lengths for the top ribs and the bottom ribs.
I drew a datum line and marked where the leading edge begins and trailing edge ends and the top curvature of the airfoil on end of a thin ply that is longer than the wing's chord.
I snipped the template to approximate shape and sanded the template.
My leading edge is a piece of 1/8" x 1/4" and a 1/8" x 1/8", arranged as an angle.
My trailing edge is a piece of hard 1/8" x 1/4".
My wing tips is made from 1/16" balsa.
The top ribs are sliced from the 1/16" prelined sheet balsa.
The trailing edge end of the top rib is further sliced along the line so that it may seat flatly.
The bottom ribs are simple 1/8" x 1/16" sliced from the other 1/16" prelined sheet balsa.
Assemble and CA LE, TE, tips and bottom ribs over plan.
CA the top ribs at the leading edge first.
Slice (chop) the trailing ends so that the top ribs seat onto the bottom ribs and TE and CA in place.
(My CA is very watery and does not stick instantly. Even though my joints are fairly tight, I think thicker viscosity would help because excess CA spreads too quickly to the underside of the pieces that I am gluing to. I think my CA may be stale because it doesn't set fast enough, even with CA accelerator applied.)
Next is to make up the dihedral, I think a single 1mm balsa sheet between the two spars is good enough. Crack the sheet at the dihedral and douse with CA. In the end I used 1.5mm bass sheet wood.
Finishing ideas
Print A4 sheets on the office copier in the following colours:
- Cream
- Aluminium
- Wood brown
- Rust brown
- might as well try drab, beige, khaki, buff or various different shades of cream, wood brown and rust brown, or even patterned type.
The conical covering of wheels
E.g. if height is 10mm, and the radius is 30mm, the compass should be set to square root (10square+30square), which is 31.62mm.
Wheel making
To make a single wheel:
Cut out single disc from thin ply (thick ply is difficult to cut with the compass cutter. Probably I cannot cut out the disc just using the compass cutter, so I shall use my snips/scissors to trim the ply disc.
Cut out two disc from 1/8" balsa, similar fashion.
Source or fabricate two large flat washer, with inner hole the size of my aluminium tubing. Washers need not be round.
If the wheel axle is too thin and I find the wheel too wobbly, then insert sleeves of plastic tubing. No tubing? Roll up paper tubes.
Use a jig to glue the washer disc, balsa facings and ply core together.
This jig is just a flat surface with a length of wire sticking out perpendicularly.
Spray the wheel assembly black.
Using compass cutter, cut out a disc from cream printed paper, to the radius where the supposedly tyre begins.
The conical covering is similarly cut out after the radius is determined.
