Try the DRI, the Red Pig

Somebody built this cartoon scale DR1.
Purportedly, the plans are from the internet.
Chris 'bought' this red model from the builder, at a price so cheap, you know it is a 'give-away', awaiting better home.
Well, Chris fitted his motor, esc and servos and was seen flying it infrequently. He did not like it, understandably so as the short coupled model ought to fly like a pig and cannot be expected to fly consistently, and I am now the owner of the red pig, when the model cannot be repaired anymore, I shall return the motor, esc and 2 servos to Chris.

I figured that the servo arms were awfully short, and this meant short surface horns to get the throws Chris wanted. The rudder horn was broken off the rudder, this is easily fixed with new horns with bigger gluing area. The main concern was the ailerons. Perhaps they worked fine when first built, but now they were too loose and the wire aileron linkages have lots of play. The original aileron servo operates via two push pull wire, attached/hinged to the wire aileron horns with heat-shrink tubing and the 1.5-2mm wire aileron horns runs in 3mm plastic tubing.

This is meant to be a quickie, so I glued on two Hitec HS55 servos for aileron control, bypassing the original linkages. I figured that there is a huge amount of wing area, additional 10gm and drag is nothing in this pig.

I got the model out yesterday, but the wind was too strong for flight trimming. Then at one point, I geared myself to try, but found the rudder horn broke loose. It was no go and I had to retire the pig home. It is fixed subsequently, with globs of epoxy.

The red nose is a discard of a Mig 15, it fits and I think it is good to stay.
If I got the model trimmed out and flying, I think a pig head figurine would look good on this model. And to cover up the two blue servos on top of the wing, how about two big cannon?

Update 1

Over Christmas and New Year period, I have been flying the DRI for maybe 10 times now.
It's like a box, it flies straight and is very stable.
Flying inverted is stable.
The rudder is very effective but I couldn't do nice enough knife-edges.
Rolling circles are ok, in a fashion.
The cowling (without the red nose) is very big and therefore draggy.
The airspeed range is relatively small due to the high drag layout.
I used a 10x4.7" prop and it could almost hover, which means it couldn't.
Yesterday, one of the motor's wire broke from its bullet connector.

Update 2

I soldered back the bullet connector but it does not work. I tried another ESC but the motor would not spin and came to conclude that the motor is damaged. Perhaps I would replace the motor with the FSD motor I used in the Katana. The model would likely be able to fly straight up.

Simplify model construction, MIG 17

The shape of the Mig 17 is a good candidate for simplicity.

The wing is swept back 45degrees. It is easier to draw then the more famous Mig 15 and the planform possesses good moment for the ailerons to act as elevons, I'd say better than a delta. The mid-section's trailing edge is straight. It increases the wing area and is a good location for a carbon fibre strip to keep the span-wise bending moment and torque moment minimal. A carbon fibre strip would increase overall rigidity of the wing.

The horizontal tail area and moment are small and is mounted high on the vertical tail. This is not good, generally, but when the wing's ailerons are elevons, it is of no consequence and presents less drag. The big vertical tail area will point the model straight.

The nose is the air-intake and is short. It is good for mounting a motor upfront. The fuselage, excluding the fin, is short. It is good to reduce needless weight. CG balancing should not be a problem.

Mig 17

1. Simplify the wing shape, forget about the un-pronounced scimitar planform, just straight 45degress swept back leading edge, forget about the minute anhedral, just straight will do, simple flat sheet airfoil.
2. Employ elevons with servos on the wing, flanked by profiled drop tanks/rocket launchers.
3. Flat horizontal tail glued to flat vertical tail and then the entire tail assembly glued to fuselage
4. Blue foam fuselage, hollowed to accept receiver, battery and esc.
5. Blue foam canopy to act as equipment hatch.
6. Using the Turnigy combination, perhaps 18" wing span is good.
7. Chuck and zoom!

Modelling a twin-engined aircraft, OV10A Bronco

Now I have 2 sets of identical motor and esc, how about a quick to build twin motored model?

It has to identifiable as a scale model and one that is easily identifiable by the public. I don't want it to fly in circles and eights, I would prefer it to be more spirited, able to perform mild aerobatics, such as the basic loop, roll and stall-turn. It has to be small and light because the motor is only about 10gm a piece and therefore has to be structurally simple, easy and fast to construct.

A P-38 would be recognisable by majority and OV10A lesser. However, P-38 has dihedral, while it is good for flying especially with the twin rudders, it is more difficult to construct because each boom has to have the wing seat in a handed manner. Also, a P-38 would be rather sizeable if I adopt the scale according to the size of the propeller. An OV10A has no dihedral, meaning the majority of the boom construction is identical, and it has largish propellor. 5" propellor is the largest my motors can handle, 4.5" would be better as tried out in the modified Bug-e fun, the model span of the OV10A would be perhaps around 25". Also, the OV10A has simple slab sided pod and boom (the awkward thing to construct would be the long and bulging canopy), unlike the P-38 which is oval in cross-section, has large rectangular wing and stabiliser, very long nose which is good for CG balancing.

I did a plastic OV10A model when I was a teenager, I chose it then because of its simple lines, perhaps I could do up a RC model now.

OV10A

• Wingspan: approx. 25" (proportioned by 5" propellers)
• 2 x Turnigy 2900kV motor (housed in the booms) and Turnigy 6amps ESC (housed in the pod), running 5x3" propellors, rotating outwards
• 2S 1000mah battery or two 2S 500mah batteries (housed in the pod for CG balancing), requiring to be fabricated, two sets of motor-wire extensions and an appropriate Y connector if both ESCs powered with a 2S 1000mah battery
• One central 9gm servo in the pod for the two ailerons
• One 9gm servo for the elevator in one of the boom, curved upwards to the elevator, substitute the control horn with an ez-connector.
• One Hitec micro receiver in the pod
• Wing constructed of 1/16" curved balsa sheet with exposed stiffeners at the bottom and a continuous thin carbon fibre strip glued under the leading edge for increased durability. Ailerons are hinged and activated ate via long aileron arms all the way to the central pod.
• Alternative wing would be more built up, it would be sheeted fully at the top and at the bottom from boom to boom at least.
• No flap-control. It seems a great feature and should be simple to construct, but let's keep it off.
• Stabilisers constructed of 3/32" or 1/8" flat sheet
• Pod constructed of 2 pieces of 1" thick blue foam, maybe I will make it knock-offable.
• Alternate pod would be balsa sides and bottom, blue foam pod nose and tail pieces.
• Canopy is a carved and sanded blue foam piece, attached to the pod magnetically for easy access to the battery/batteries, ESCs and receiver.
• A more attractive alternative canopy/cockpit, but which involves more work, is to form a clear canopy. Simple push moulding is out because of the bulging shape of the canopy, a more practical approach would be to carve a male mould from blue foam, and shrink a clear bottle over it. With the pod constructed, balsa sheet will be used for the two bulkheads and canopy/cockpit floor. This underlying frame is then fitted out with dashboards, headrest etc and painted and the two pilot figurines installed. Then the shrunken plastic piece is glued to the underlying frame and the excess plastic trimmed. The canopy is then taped for the canopy frame and the whole assembly magnetically mounted onto the pod. The canopy is a prominent feature of the OV10A, a solid blue foam piece while dimensionally accurate would not be able to create much interest.
• Booms constructed of 1/16" balsa sheet, with bottom access (hinged and taped) to swap motor wires.
• No rudder-control. I would like to have control over the twin rudders, but to maintain simplicity and keep the weight down, I may have to forego this. If there is going to be rudder-control, I would use 2 x 5gm servos housed in the booms and connected through a Y to the receiver at the pod.
• The pod and booms could have 3mm aluminium tubes glued in to receive the removable undercarriage, made from 1.5mm piano wire, friction fitted into the tubes.
• Hinged with Guardian's surgical tape or narrow pieces of filament tape, covered with tracing paper (bottom of wing shall be bare), white glue coated, sprayed basic colours, unless I can find suitable coloured film to iron on, which is the preferred choice for lightness.

Food in the airport terminal is expensive

Food and drinks in airport terminals are expensive.
If you have to eat and drink, you pay 2-3 times more than you would outside.
The solution is to choose Fast food. This morning I ate at Subways. It is not what I would normally have for breakfast, but I don't loathe it , so I had the $5 combo.

Maybe these Fast food chain has to maintain contact with their customers, and they don't feel comfortable to increase their prices.
If I was to ask Killiney or food court operators, they would probably say the price is higher because of higher rental and their employees have to travel far. These reasons apply to Subways, MacDonald, Burger King and the like.

The main differences between Krisflyer Gold and Silver/non-member

1. Silver does not have access to the lounge. The sofas, papers, food and drinks. Nobody really watches the TV, quite a few uses the wifi.
2. Silver joins the common queue for boarding pass. Easily double the time to check in.

Point 2 is, on reflection, interesting.
It is not as if Gold staff works faster or we don't have to queue.

Can we interpret that the common queue needs more checking in staff?
Is there a conscious act of limiting and inconveniencing to augment the image of the Gold class?

Modified Bug e-fun flies

Some 1/16" balsa sheet is used for ailerons,  elevator and rudder. All control surfaces are hinged with surgical tape from Guardian. 1-1.5mm pushrods are Z-bend at the servos (because I don't want to enlarge the servo arms' holes), accorded adjustability with EZ connectors from GWS on control horns that have the holes drilled larger (to 2.5mm diameter) to accomodate the connectors (both from HobbyKing, the horns were not what I ordered but are usable).

Servos are 9gm for ailerons with two push-pulls, and 5gm for rudder and elevator, mounted in a single file on the top of the model, superglue in placed. In future, I shall not use the 5gm servos that I bought from Jethobby. These 5gms were intended for Mini-Popwing but which I didn't use them because they stalled too easily. I installed them on this bug e-fun but they stalled occassionally. These 5gms servos are too weak.

The Turnigy 1806motor and 6A ESC (both from HobbyKing) and a GWS 5x3 propellor provides ample thrust. The motor is mounted with its radial mount (I deem the motor shaft too short for direct grip with nylon ties) on a 2mm ply-faced 1/4" balsa firewall with 2mm socket bolts and blindnuts (the radial mount and firewall probably weighs as much as the motor itself). The firewall is first glued to a 2mm carbon fibre rod pylon. As the throttle increases, the whole motor rotates downwards, giving more downthrust. Interesting to have variable downthrust but not a good idea for reliability. The rod was then replaced with a 5x1mm carbon fibre strip. No more variable downthrust but it snapped when crashed. Finally, the firewall was just epoxied onto the nose.

With Hitec receiver in the canopy region, and a 450mah battery (bought from Rotor Hobby, tagged as 500mah) push fitted in a slot below the wing, the model flies good. There must not be too strong of a gusty wind.

It flew ok. Rolls, loops, inverted are ok but not straight and true. Stall turns are iffy with the smallish rudder and I got about 10 minutes of flight time. Maybe it is the Turnigy 6A ESC, it is warm even at zero throttle and I didn't have this symptom with the Turnigy 10A ESC. Anyway, 10minutes is good enough, I like the smallness of the 6A ESC and will use them, but next time, I shan't use the 5gm servos, I shall use the 9gm servos like Hitec's HS 55.

This experiment was done to evaluate how the 1806 10gm motor feels. I find this airborne package ok, although the 6A ESC was warm and the 5gm servos quite useless.

Now that I have an idea of what it can deliver, I can do up more interesting models using them.

How about a scalish Gee Bee Model D Sportster or since I have two of this motor and esc, a scalish twin of some sort? Short-nosed subjects like the Sopwiths are still out of bounds until I can figure out how to concentrate the weight to the nose which currently. Maybe I will find reliable 5gm or sub-5gm servos one day.

Update 16/12/2013
My two Mini-Popwings are down. One with a motor wire pulled out of the connector and the other a jittery servo. I am left with the mini piper cub and the Bug e-fun. For 'challenge', I flew the Bug e-fun yesterday.

I flew 6 batteries, during these flights I added 10gm of lead to the tail. The model was nose-heavy to start with.

The flight times of flying freely with full use of throttle and conservatively with gliding time was not of appreciable difference. The batteries lasted about 9 minutes for both forms of flying. I thought it would either be the ESC or that I have over-propped the motor with a GWS 5x3. I swapped in a 12A Hobbywing's for one flight. It seemed slightly more spirited, but the flight time was similar. Perhaps the 2900kV was overworked and hence drawing more amp while the propeller flips over at less than 90% of the 2900kV. I tried a GWS 4.5x4. This is better.

I could do rolling circles with this model. The rudder is however too small and the rolling circles relied on elevator input instead. Perhaps if the rudder is bigger the model might have a chance of doing knife-edge. (I doubt it, but still, it is plausible)

Bug e-fun

I have an orange glider, Bug e-fun or something, around 600mm wingspan.
I have receiver, servos (rec from the flea, 1x metal servo from butterfly and 2x 5g servo which was aborted from Orange), new motors (1806 or something) and 6A esc (turnigy), both from Hobbyking.
Let's modify it so I can test how much thrust I can get from the 1806 motor/esc and GWS 5" prop combo.

Bug-e fun has low dihedral.
It didn't flip over and remain right side up when I last flew it.
It ought to be enough, but maybe it isn't.
Maybe the introduction of a 5" prop will make things too interesting.

I must have rudder, so let's settle for full-house and have ailerons and rudder control.

Cutting and bending steel wire components

A thought on cutting and bending steel wire.

I know things like bending radius and how to calculate cut lengths based on steel property, but this knowledge is applicable only to rebars and not the small wires used for modeling.

A bending jig would be useful for our purpose, but I think it is an over-complication and is beyond me. I rather rely on simpler tools, like a plier and an optional side cutter. I have been doing that but I was not successful with making repeated steel wire components (whether handed or not). They just didn't come up identical.

One experiment had me trying to grip and bend two wires at the same time. There are obvious limitations, and it didn't work well.

I think to be accurate, the wire has to be bent individually (when using a plier) and the bend points must be marked identical, which means it must be precise enough to the nearest half millimetre or so. A steel wire is too small and my eyes too old to mark the bend points accurately. I need something that is easier to measure, mark and see. My proposed solution is to first tape the wire with masking tape, then to measure accurately and mark on the masking tape. I will try that when the opportunity presents.

Model Inventory: Red Butterfly, off to a good home. Flea stripped. FMS P51. Katana.

I gave up the Red Butterfly to old man Wong (including the two feeler/eyes for balancing).
I have to "make room".
He has sinced stripped and returned me my servos, esc, motor and receiver. I have now a vacant model memory #4.
Hope he can make it fly and enjoy it.

I didn't manage to get the flea to fly and while it is not beyond repairable, I gave up trying. Maybe someday I will do another one, I have some hunches.
I will strip the electronics out and re-use them somewhere.
I think the wings are fairly good and so I will keep them.
The fuselage will be junked and this frees up model memory #2.

I will not repair the pranked FMS mini-P51.
I will strip for salvageable parts and this frees up model memory #1.

Undecided about the fate of Techone's Katana (the second model).
I am not up to repairing the cracked carbon tube of the fuselage aft of the wing's trailing edge.
Maybe I should scrap it too since it is not seeing much use anyway.
This will free up another model memory.

Then I will be left with the two Techone's Mini-Popwing (#5 and #7), the mini-piper cub (#?), the canard (#?)

When is it time to replace the lipo?

Not how much the battery is bloated. It seems some batteries bloat more than others while still performing ok and it also depends how hard we used them. I have not seen anyone advising to throw away a battery just because it is bloated.

Observed symptoms when balance charging:

• When a 2S doesn't reach 8.4v, a 3S 12.6v, and ends up for eg 8.2v.
• When the difference between cells on a fully charged battery is almost 0.1v
• When a full balance-charge for a depleted battery is only half the battery's stated capacity.
• When the balance-charger times out at 120mins.

Observed symptoms when flying:

• When you observed that you have barely enough power for level flight near the end of each flight and yet the depleted battery reads 7.4-7.6v for a 2s.
• When you observed that the power model loses impetus suddenly on 2 consecutive occassions.

Reunion of MiniPopwings

Orange, meet Fire.
Since you flew out of sight and I couldn't find you, Fire has been doing what you did well in your element.

Fire, this is Orange.
When Orange was but a speck in the North-West corner of the sky, with wind North to South, it turned invisible against the blue and white backdrop, all it took was just a brief moment of lapse, as much time as it took for me to look behind my left shoulder.
Orange was brought back about 2 weeks later when Angus found it in his school compound. His school is North East from where I was flying.

Now I have two MiniPopwings.
Orange a bit weathered, but functioned nicely (receiver, esc, motor, servos, everything except the 2S500mah battery), infact, I think the many torrential downpour it has experienced, has somehow made its EPP smoother and it seems to glide better then before.

Yesterday afternoon, it flew more than 20 minutes.

Buy another Mini Popwing or scratch build a dragonfly?

A friend urged me not to buy another Mini-Popwing but to scratch build a dragonfly instead.

Well, two different issues there.

The kit from Rotor Hobby sells for SGD 63.00 before 10% member discount is applied. It flew great and the kit includes a 10gm 2S motor from Tiger-Motor, retails at SGD 39.00 from Jethobby. Effectively, the EPP wing kit is less than SGD 18.00, and I do like that tiny motor, it fires up my imagination, I can use it for small models using GWS 5x3. I would have gladly bought two in an instant if Jethobby sells it at half the current price. But we are getting nowhere with 'ifs'.

The full-house Red Butterfly flies great, vertical take-offs a plus, so is the mini field requirement, but I am bored with it. If I do up a dragonfly, it will be RET this time, for relaxing gliding guiding.

The forewings will have straight leading edges (adapts well to carbon fibre tubing) and have dihedral, maybe 7-10 degrees each wing. If I use 5mm carbon fibre tube, I can use 2-2.5mm wire joiners, and the root jointed with dry wall joint tape.
The rearwings will also have straight leading edges, with small carbon fibre rods, be flat without dihedral and of shorter span.

The head and thorax of the dragonfly can be carved from blue foam. Suitable transparent bottle ends might be used as eyes, but so far I can't think of any plastic container which has spherical ends. Alternately, two largish almost round discs of blue foam may have to suffice for eyes.

What's the colour of the head and thorax of a butterfly? Don't know but not blue I would think. The eyes should be darkest then the thorax and remaining head. If I leave it as blue I should at least use a black marker pen to draw diamonds on the eyes.

The firewall will be 2 pieces of 2mm ply cross bonded to the head, set slightly rearwards so that the eyes can be like side cheeks to the motor, obscuring the motor from side views.

The thorax should have a V-cut for the front wings and a flat surface for the rear wings. The battery and ESC should be in the head/thorax region and the receiver slightly aft. Two servos will be mounted at the rear of the thorax, one to each side.

Choice of abdomen construction will depend on type of tail I want.

Foam board would be good for a V-tail or a conventional inverted T tail, but a 5mm carbon fibre tube would be an even better choice, for durability reasons. If I were to do a swinging tail, then I must use a carbon tube for universal joint.

So.. for a V-tail (to clear the grass), I would use a carbon tube as the abdomen. One end embedded into the blue foam thorax in-between the two servos, with two 1/16" balsa sheet tails jointed at 110 degrees ( I remember 110degrees to be a typical angle), covered with paper/tissue on the top surface for strength and hinge at the rear end. And if I need more fin area, I will add underfin to the boom.

Ooops, warping? ok, cover both sides then.

My Techone Mini Popwing is no more

Pilot error.

The Mini-Popweing glides fairly well.
Power climbs and glides gave me 20minutes on a 2S500mah.
My residual voltage typically varies between 7.1-7.5v, way above the ESC's low voltage cut-off, but it does not have sufficient thrust to fly.

My routine is to fly it full-power up high, then chop the power and let it glide down low.
On its last flight yesterday, I got it up to a speck, the power was cut-off and it was gliding when my eyes strayed to look at a tri-rotor behind me for a second.
And I couldn't find it in the clouds anymore.

Simply put, pilot error, it climbed too high for my eyes.

Techone's Mini Popwing

I bought a Mini Popwing kit from Rotor Hobby.
In the box, there was the assembled wing, a T-Motor's 1306, a 5x3 GWS propellor, and a bag of accessories.
I also bought a 10A ESC and got Rotor Hobby to solder on the connectors to the ESC and motor for a workmanship fee of $6.
I also bought two 5g servos from Jet Hobby, $10 each.

Back home, the assembly is fairly quick. It took about one and a half hour to have the motor and servos installed, the carbon rod wire ends sleeved with heatshrink tubing.

The two 5g servos had short lead, I had to open up the servo holes to accomodate them. They plugged in to the Hitec receiver but just barely. The receiver cannot be placed at the designed bay, and on testing the elevons, one servo could only pull an elevon but not push it. This is due to either stiff hinge (EPP hinge) or that the servo is just too weak.
I replaced one with a Hitec 9g servo (HS-55) and it worked great. It worked so good that I discovered that the other 5g servo's elevon movement was much less than the 9g, so I replaced that with another 9g servo too.

I set up reduced dual and exponential rates on my Optic 6 Sport so that the maximum deflection is eyeballed at the recommended distance. The balance was slightly aft, so I trapped a bit of weight (maybe 3-5 g) to the battery compartment to bring it approximately at the balance point recommended.

Test flight was done yestereday. A bit of trim and the wing flies great. Not sensitive, but needed speed to do a loop. Rolls are ok, not axial but acceptable. I needed quite a lot of up trim, so I removed the additional weight and did my second flight. After some trimming, it flies ok but then I realised that the pushrod assemblies were sliding, the superglue did not work. I was at the flying field, I used some cyano from an Indian chap who was flying there but one linkage worked loose as well, rendered the wing unflyable.

Old Mr. Wong came, said he will return home to bring his plane and bring me more superglue (by then the Indian chap whom let me used his superglue has left). Before Mr. Wong return, a Malay man came and he offered me his 5min epoxy. So kind of him. I used his epoxy (he bought the epoxy from Jet hobby, the epoxy mixes well, doesn't get tacky (much) after cured and is apparently transparent, ought to buy them myself) and the offending pushrod is holding up. Mr. Wong returned with UHU Por, it would probably work, after a longish wait.

I changed my flying style for the wing. Nobody's going to do combat with me, so I flew full throttle up to a speck and did gliding instead. The wing is a fair glider. As it slows there was wing rocking, but it is stable and this ought to be attributed to the design. On 2S-500mah batteries, I managed to fly a good twenty minutes. I found two locations which offers some occassional lift, one towards the CD HQ and the other along the trees.

Combat anyone?

I've been flying 3D and it gets kind of boring when I cannot progress beyond the rudimentary first stage. So I've been trying the Flea, flying the Red Butterfly, and thinking of more 'fun' models. Last Sunday I think that flying combat would be cool. I think it would be interesting if two or more models can be in the air trailing streamers behind them and each manouevres  to cut his opponent's streamers.

Rules have to be madeup, models should be durable, fast and manouevrable, cheap and look something like a plane that actually saw real combat.

I'm thinking of simple profile fuselage, flat compressed foam wings, 1/8" balsa stabiliser and elevators, beefed strategically with 2mm ply doublers, 5mm diameter CF tubes, 2.5mm diameter CF rods (slips inside the tubes). The wings need not have dihedral to keep things simple and maybe positioned somewhere closer to the centreline of the model for perhaps better flight characteristics, convenience, durability, and strength.
The motors should all utilise the cross-mounts so that motors can be swapped easily. This in turn is to be fixed to 3 or 4mm plywood firewall with bolts and blind nuts. The firewall is supported on 2mm ply pieces which is glued to the 2mm ply doubler. This feature's advantages are:

• easy swap of motors upto 28mm diameter
• easy placement of 3S1300mah batteries, ESC and RX

Two servos should be enough, one for the ailerons (or just one aileron) and the other for the elevator. And in the case of flying wings, e.g. ME163, as elevons.

The goodlooking side of the profile to be made from 5mm foam, if it is a radial engine, the spinner maybe left off, but if it is a sleek spinner faired nosed fighter, the foam profile should include the spinner (the propellor spins infront of the spinner). The left side of the fuselage should be covered with paper printout of the fuselage profile, this way the model is not bland and I don't have to spend too much time to pretty it up.

The wings are similarly constructed of 5mm foam, covered with paper printout, right over the hingelines of the ailerons.

The wings should be around 30" for 3S1300mah, 28mm motor, and maybe 24" for dualsky RTR motor.

Red Katana Wing Flyer

The Wing

I installed two servos onto the wing of the deposed red Katana (Techone Katana), and found one aileron has much less throw than the other.

I paired up the two servos before hand and am sure they are fine. The fault lies with one of the aileron horns. One of them is loose, it has squashed the epo and is taller then the other, so I applied hot glue and both throws looks ok now.

I decided I want the servos lead to pass up through the wing to the top surface of the wing. Some slices with an NT cutter and a push with a screwdriver made this possible.

The wing is completed.

The Pod

This is constructed of 1" blue foam.
A blank of 3" wide blue foam is offered to the underside of the wing.
I decided to place the ESC at the bottom of the wing and gourge out 1.5" strip from the bottom foam piece.
The receiver plug and T-connectors are pushed through the same hole created for the servos.
A 3" foam offcut is cut into three pieces, the central being 1.5". The two external pieces are gorilla glued flat onto the bottom foam piece, at the battery compartment area, temporary banded with rubber bands.
Use cling firm around the middle foam piece so the expanding gorilla glue will not glue it shut.

Next construction step will be to decide if it is necessary for a top foam piece, I'd rather not. Then it will be preparation of firewall and the optional step of putting a nose piece.


and

Red Butterfly, small field Flyer

The Red Butterfly can fly tightly.
Low wing loading allows model to fly slowly at minimum throttle and the large rudder has good yaw authority. Rudder coupled with ailerons resulted in small turn radius, and crossing controls will direct the model to do a flat turn.
What is necessary though is 3S to overcome all that drag from the wing. Flying on 2S will mean the model will lose the energy and lose height.
Maybe 2S will work on smaller wings.

Flying the Red Butterfly, Vertical Take Offs and assisted vertical descends

On 2S500mah, it flies ok with two antennae, sensitive with one antenna, not acceptable with no antenna. It clearly needs more voltage and I think batteries with higher discharge rate then 15C is desirable. As it is, there is not enough power near end of flight and there are residual current in the batteries.

On 3S800mah, it flies great with one antennae, sensitive with no antenna and plenty of thrust. There is so much thrust (near the beginning of each flight), the model can take off vertically from the ground.

I couldn't manage hanging off the prop for hovering and then to attempt vertical tailfirst landing. With a strong headwind which is greater then the flying air speed, the model can appear to retreat tail first and usually at this slower air speed, the model can appear to descend vertically, although in a 'flying' posture.

The Red Butterfly flies

The red butterfly flies much better after modification.
The photo above shows the two modifications I tried.
I have the Augmenter ring and the two feelers/eyes.

The two eyes were taped onto the wing. Round balls were glued to the ends of the two carbon fibre strips and 5gm lead weight taped onto the carbon fibre strips. It transforms the flight from fluttery to a proper controlled flight. With the CG brought forward, it became controllable.

The Augmenter was tried with 3S800mah motor. It is actually a detractor. The speed envelope reduced, it seems to help a bit on high Alpha flight, but only one flight was made with the Augmenter and it was subsequently removed.

With the Augmenter removed and the eyes fitted, I flew it with 2S500mah. Only managed to fly less than 4 minutes on each battery. Probably because I had fitted a cut-down 10x4.7 prop, and unbalanced at that. I did it because the 7x4 prop broke when I crashed the model.  

Both modifications look cool. The yellow eyes are a keeper, but the augmenter ring not so, maybe I will keep it for 'special occasion', but only after I sprayed it silver front and red back.

The other modification since then is the application of yellow vinyl to the top of the wings. This helps visually. On a bright day, the yellow shows through to the underside, but it is no issue really, as the visual aid is for the moments when you can't see well, which doesn't happen on a bright day.

STOL/VTOL Single Motor

A single electric motor, 10x4.7 prop, 45degrees canted upwards to provide forward and upwards thrust, just behind the CG, ducted with controllable vanes at the bottom and narrowing to a vane-linked elevator and huge ailerons and rudder for the other two axis around the CG.

The duct to be made big enough, enough void within to even out the swirls and pulsation of the prop fan. One entry to the prop fan, two main exits with one at the vaned area and one at the rear. Net area of vaned area and rear exit should be lesser than the entry. There shall be sliding plates at the diagonal corners of the duct below the prop fan to provide torque correction force. Instead of linking it to the aileron servo, we can leave it manual, adjusted after flight testing.

The bottom vanes shall be at 45 degrees pointing rearwards, but can be closed. With the vanes closed, the model is to fly like a normal powered plane with the pair of wings providing lift and countered by the downward force of the elevator. With the vanes opened, the elevator shall move upwards to push the tail down so as to compensate the nose droping moment.

The pair of low aspect ratio wings shall be located relative to the CG, to glide when the elevator is at neutral (vanes closed condition). There shall be dihedral for stability as the ailerons are omitted for the first test model. The wings to be top mounted, just below the lower of the prop fan disc.

The fuselage is a longish pod to a rectangular box. A large fin is mounted on top of the box, and the rudder extends to the box. The elevator is cut out from the bottom of the box.

Model to be 3 Channel. Throttle, Elevator, Rudder. 2210 motor, 3S1300mah battery, 10x4.7 propellor, 2 servos, 30A ESC, Hitec receiver.

Yellow Butterfly, Red Butterfly, Red Savoia S13

My Flying Flea, aka Pou du Ciel, could only crash and is converted to the Yellow Butterfly by the additional of thin oval discs at the rear wing. It still didn't fly. On the last test, it flew up to 6-10m high and dived straight down. Maybe I should return the 2S500mah battery to the battery compartment and make 3-5degrees of incidence on the front wing. Alternately, I am considering modifying it to have elevators at the rear wing.

The depron quick build is the Red Butterfly, it flew, barely.
It has the flying characteristics of a butterfly, Muhamad Ali's word: 'float like a butterfly', except that I have a hard time doing the flight corrections. The 3S800mah battery is already placed immediately behind the firewall and it is still tail heavy.

Instead of fixing nose weight, or ripping the elevon/rudder servos and mount them forward and replacing the pushrods, I shall add some interesting structure ahead of the CG. It should both be interesting and also serve as nose weight.

Two ideas, the Augmenter and the Feeler.

The Augmenter
Cut out of McDonald's salad cover, this circular cowl is gracefully curved and let us call it the Augmenter!

So called because, it shall:

1. increase the thrust from the propeller, 
2. render the model stall proof because at extreme angle, it will still provide lift at the nose, enabling the model to hold higher AoA,
3. enable the model to land vertically on its tail,
4. enables the model to have slower and more constant airspeed in climbs and dives,
5. looks cool because relative to the 7" propeller, it is so huge (I think I shall spray it silver).

The weight increase will be very slight, only a few grammes.

Will it work? I don't know, even if it is detrimental to the performance or if it makes the model more difficult to fly, it is interesting.

The Feeler
How about some flexible wire/rods stuck on to the nose, so it looks like the pair of feelers of a butterfly?
I could add small plastic balls at the extreme end, for safety (hahhahah) reasons, both visually and practically.
Wow, am I a show-off?
Don't care, so long as I am having fun.

Will it work? There might be complications, but having long feelers infront of the propeller disc must be good at least for the CG as it presents long moment arms so I can use the least weight to bring forward the CG.

With all these ongoing projects And yet, I'm thinking of doing a quick build of a red-white Savoia S13.
Go Outerzone, there's a peanut plan.
Let's see, the mods I would make:

• sheet balsa everything, fuselage, tail, wings, nacelle
• engine nacelle integral with the top wing
• engine nacelle to house the aileron servo (only the top wing has ailerons), esc and motor (to use the Emax motor currently in the Red Butterfly)
• carbon fibre strips as cabane struts with nylon fishing line riggings (the 0.33mm thick type)
• Both upper and lower wings, with the cabane struts, engine nacelle, demountable in a single unit from the fuselage boat, the esc lead and servo lead is to be connected before fixing the single unit (dowel and screws or rubber banded?) 
• right under the lower wing, in the fuselage (the boat/pontoon), will be the elevator and rudder servos.
• Forward, in the nose will be the receiver and 3S battery
• The top of the nose, until the cockpit, shall be removable, this means nose to rear of the trailing edge of the lower wing is open for inspection, modification and reinforcement
• elevator and rudder pushrods shall be the 0.8mm wire running in nylon tubing

How difficult can this be to build, fly and maintain? If I get sick of biplane flying, I can just do up a wing with motor pylon mounted and fly it as a 3 channel monoplane model.

Why a flying boat? Well, a flying boat is supposed to ROW (Rise-Off-Water), so there's no wheels around, and maybe one day I will fit a motor powerful enough to be able to take off grass! ROG, Rise-Off-Ground or more appropriately Rise_Off-Grass!

Red Butterfly

Red Butterfly

Name derived from its flying wing planform and huge elevons which, together, looks a bit like the wings of a butterfly. Red, because red packing tape has been used.

The idea is to have a simple depron flying wing, huge elevons and rudder, deep fuselage profile for 3D type of flying.

Depron is weak, so carbon fibre tube has been used on the leading edges of the wing and fuselage, and carbon fibre strip on the hingeline of the wings. Both tube and strip were sized very close to the 5mm depron.

Flying on 2 cells lipo (2S500mah) was attempted, it flew like a kite, meaning it can go up, but extremely difficult to fly, the wind takes over and flying is more like making constant corrections to the model, sometimes successful, sometimes not, and never consistent.

Then I placed a used 2 cells lipo as additional nose weight and it flew well enough.

So on the next trip, I used 3S800mah, more controllable but plenty of quirks. I find it can fly, but the CG is too far back. When the model was inverted, instead of diving towards the ground, it flew upwards.

A control horn broke from the model, curtailing further flying, but what I would do perhaps, is to install the 3 servos right behind the leading edge to bring the CG forward slightly, possibly devise somthing to prevent the 3S800mah battery from falling out (happened twice, model floated down in a level plane due to the rearward CG).

To improve visibility, I should add some color trim on the top, perhaps the yellow vinyl sticker that I bought.
To increase interest, I may use McDonald's plastic cover for the salad as a huge cowling, who knows, maybe it allows the model to 'parachute' vertically tail first?

Repairs and riggings

With so many crashes and repairs needed to the Flying Flea/ Yellow Butterfly, I think I have become more adept with repairs and riggings.

 

I have had 2 broken propellers and a few other ailments:

• the 0.65mm nylon rigging line does not bend sharply when needed; I replaced with white sewing thread, although now I replaced the sewing thread with 0.33mm nylon fishing line to address the other issue of snapping;
• rigging lines pulled out of the attachment lugs; I replaced the broken attachment lugs or glued on a small washer; and
• the attachment lugs themselves pulled out from the wings; I glued the lugs and clamped them to the wings until the glue is cured; the pvc wing pivot broke; I replaced that with
• the wing pivot fabricated from PVC cover sheet sheared off; I used another plastic horn to be the wing pivot and superglued in placed. Similarly when the first plastic horn snapped, I employed the same except that I superglued it temporarily in placed and then epoxied the horn and struts;
• the rigging lines snapped; I tried joining with additional piece of thread, forming loops at the free ends and using that to attach the new thread and finally using 0.33mm nylon fishing line;
• the tension of the rigging lines collapsed the cabane struts; I had to re-rig the whole model, good thing too as the previous horn was displaced before the glue cured, leaving me with a lower forewing.

After so many re-riggings, I employed push rods for the wing because previously, when I was using 0.65mm nylon line or sewing thread as pull lines, I had issues with adjustability, and the rubber band to make the forewing pitch downwards places additional strain on the servo and linkages, the servo hummed.

 

Using push rods has additional benefits. Because the wing lugs are in board, it makes sense to install the pushrods first and then proceed with the rigging. Previously I had installed the primary roll rigging, then the secondary lateral rigging and then the incidence pull lines. It is difficult to install the inner pull lines as space was so limited and the lines restricted my fingers this way and that.

 

With the inner pushrods secured, they held the wing at the approximate incidence and I proceeded with the rigging. The first rigging is the roll rigging, and then the lateral rigging. All together, only six pieces of 3mm aluminium tubing, each approximately 3-4mm long are used. 2 for the 2 ends of the roll rigging line, 2 for the 2 ends of the lateral rigging line and 2 at the outboard pivot points where all four lines converged, so I can lock the roll and lateral lines inplaced in one go.

And if I shall have a chance to do up the main wing's actuating mechanism again, I shall fit the arm through a slot cut in the aluminium tubing because the arm now is worked loose and has slop. Good enough for pulling I guess, but not for pushing and would never be good enough if I put tail elevators.

 

Reincarnation of the Flying Flea into the Yellow Butterfly, although it still crashed

The problems with my flying flea so far appears to be: the short range of CG (usually it appears nose heavy but as this is complicated by the AOA of the forewing, it is kind of difficult to assess until it is flying), the securing of the 2S500mah battery (Mr. Grayson, the grey foam pilot couldn't put his back to the battery tight or long enough), the constant loosening of the wing actuating horn (so I have slop) and the general fragileness of the rigging lines which are a pain to re-install.

The two sets of forewing rigging lines of sewing thread has snapped. I the forewing rigging thread with 0.33mm fishing line (40 cents investment) because the sewing thread snapped frequently.

I tried to tackle is the short permissible-range of CG. I would prefer to distance the wings a bit more, to give it more moment arm, but there is not much chance with such a short fuselage. Instead, I glued on two sticks of tail, fabricated from carbon fibre rods and two oval discs of clear pvc sheet (book cover material) joined at the rear with a flat carbon fibre strip. This gives the planform an appearance closer to that of a butterfly. And since the model is sprayed yellow, hence, Yellow Butterfly. So it is not a flying flea then, but, let's at least get it flying.

I found I had to add a 5gm weight to the rear of this double tail (or third pair of wings) when the battery is in the cockpit if the model is to balance at the calculated CG point. So I made a hatch at the bottom of the fuselage, just behind the former of the cockpit and placed the battery there and removed the 5gm of leadweight. Seems a bit tail heavy but I like to try that because many taxi runs ended up nose-over, maybe the rear wing is lifting too much.

With the 0.33mm nylon line forewing rigging, slightly collapsed cabane (resulting in a lower forewing), transparent pair of third wings, and battery behind the cockpit backrest former, the model lifted off the ground wallowed in the brief seconds when it is in the air before snapping inverted and dived onto the ground. Clearly, a sign of rearward CG.

The model is broken again. The front cabane struts broke from the firewall, the starboard horn teared (including tissue) away from the foam wing.

Every crash is a re-build opportunity for improvement.

But maybe I will lay off Yellow Butterfly for a while and do up the RED 3D Butterfly (inspired by the Yellow Butterfly but with single depron foam elevon wing, deep fuselage and rudder). Another possible model I might make before I continue with the Yellow Butterfly is to do up a tandem wing flyer.

Concept for tandem winged flier
Take two chuck glider wings (18" span, 1/4" x 4" balsa, polyhedral for the front and dihedral for the rear), separated by a fuselage with at least 6" between the TE of the forewing and the LE of the rear wing, pair of elevons at the rear wing, with a rudder set 6" away from the TE of the rear elevon. Die, die must fly.

Carving a 1/12th scale pilot silhouette for the Flying Flea

Start with a block of foam and decide the approximate dimensions of the pilot figurine. I want a 1/12th scale with height of 5'9", i.e. in model size, 5.75".
I drew the outline on paper.



Cut a piece of L-shaped foam block and trace the outline on one side and the backside, and carve. The shorter length of the L is for the arms.

The carved pilot turns out to be a muscle man, and appears more than 6 feet in scaled height.



Start trimming by lessening the shoulder and chest. Now the carved pilot of approx. 5' 9" of scaled height looks like a child because the head is big compared to the slimmed shoulder.

I could carve the head smaller, but never mind.

I would check it against the Flying Flea first and play around with it.

This torso is a silhouette figurine, it will be glued on a 1/16" balsa sheet, the assembly will be glued into the cockpit, leaving a space between the back of this figurine and the cockpit rear former in the plane.

The space is for slotting in the 2s 500mah lipo battery as I think I might have to have my battery against the cockpit rear former . The battery will be held in placed by friction and compressible foam figurine.

I used grey-black foam because:

1.  that was what my IT colleague has on his table and it is light, plenty of air in the foam; 
2. I don't intend to paint or do details; and
3. grey-black offers great silhouette shading. It ought to be visually pleasing when the Flying Flea is flying (if it comes to that stage). 

Maybe I should install 1/4" balsa rails into the cockpit and mount the assembly on that instead. The assembly could be mounted with magnets or velcro, something like that, then I will be able to remove and change the position of the pilot assembly anytime.

Broken wing pivot

The wing pivot didn't break, the plastic horn broke, and the attachment to cabane struts also broke.

The wire in the ez-connector allows length adjustment of the pull lines. Because the pull line is in " \/-\/ " fashion, with the "-" being hooked to reduce the two "\/", very fine adjustment can be made, every unit length at the hook equals 1/4 to the wing displacement, approximately.

Repair:
The plastic horn has been replaced without the pvc cabane attachment. I am relying on superglue, but maybe I will wrap some thread around to secure.

The many crashes of the Flying Flea on Sunday

Sunday morning, I decided to go out to the centre of the field where there's sandy ground and do a few taxis. Directional control not good, I suppose I will have better chance if the tail wheels were of softer material than ply discs so that instead of skidding over the place, the tail wheel could roll along instead. Maybe next time an opportunity present itself (such as lost of tail wheel?)

There were a couple of nose over if I go too fast.

In the afternoon, I thought about it and think that that is probably because the rear wing is providing lift, so I zeroed in on the wing incidences.

I fabricated adjustable pull lines, and I think I have both wings along the same incidence.

In the evening, the wind was even stronger, too strong in fact, but I gave the wing some more incidence (+25 in the digital trim), hand launched and it looped, inverted for a moment and crashed.

This happened twice before the pivot horn snapped.

Now I have to replace the horn and probably do up the whole rigging again before the next test flight.

The many crashes of the Flying Flea on Saturday

On Saturday:

1. Acceptable wind condition, hand launched, nose dived and smacked the ground, nothing broke.
2. Moved the 2S500mah battery out of the intended battery slot compartment, placed it in the cockpit. Acceptable wind condition, hand launched, nose dived and smacked the ground again, one of the rigging tabs came loose, together with a strip the tracing paper covering.
3. Glued back the rigging tab, taped the battery just in front of the rudder. Acceptable wind condition, hand launched, looped and smacked the ground once again, the wing pivot made of 0.25mm clear PVC sheet broke, the hinge at the fore wing pulled out of the foam.

Back at home, I placed the damaged model on a table, a gust of wind flipped the model, sending it on its fourth crash upside down and broke the rudder hinge.

I removed the 0.65mm nylon fishing line rigging wire and pull lines, took a small plastic horn and glued it to the apex of the cabane struts to use as the wing pivot. This took the front wing forward and higher. Deemed desirable based on the internet search of  a forum for full size Flying Flea.

It listed a few key points:

1. CG to be  23-26% of the total chord.
2. The front wing must not overlap the rear wing.
3. Use latest reflexed airfoil (which I can do nothing about it unless I want to do a new model).
4. More than quarter chord vertical distance when the front wing is at maximum angle.
5. 0 degrees incidence for rear wing, 0-12 degrees incidence for front wing.
6. Not to use older designs (which I happened to based my model on, well, can't do much there).

 The plastic horn will bring the front wing forward and higher, while not in keeping with at least one key point, it ought to improve the dangerous dive somewhat.

While trimming the sheared off rudder hinge, the rudder lug points broke. These items were fabricated from 0.25mm PVC clear sheet. I think it is not flexible enough. Another lug point at the wing had the lines pulled out of the centre hole too.

So I repaired the broken lug and horns with more 0.25mm PVC clear sheet, as that is what I have and tried using tape hinge for the rudder. The taped hinged rudder looks ok, but on testing, it was too inaccurate, the rudder cannot centre well because the hingeline is only 2-3cm. I sewed on figure 8 thread hinges with yellow thread (the fuselage and rudder is sprayed yellow) and this is fine.

Using white thread, I rigged the model. I did not have to use aluminium tubing anymore. The thread is more flexible than the 0.65mm nylon fishing line and a few half hitches do the job admirably well, more importantly, no curved lengths of rigging which lead to spongy lines.

In the evening (after a trip to jethobby in the afternoon to buy a non-in-stock replacement motor shaft for the AS2816 and ended buying a FMS mini Mustang of 800mm, and assembled the Mustang), using excel determined the CG to be at 2.75" from the front wing's leading edge.

Flying Flea

Last night fitted 2 extension arms to the wing actuating mechanism.
Just 2 short pieces of thin wire, formed into eyelet at one end of each wire piece, and heat shrunk in place.

Then I proceeded to lace up the pull-line.
In order to have it taut, it is necessary that at all bending points, it has to be made sharper.
The problem it gave was that the wing would be pulled down in the process of tightening and if you held the wing, the wing actuating arms would be pulled upwards.

One hand on the loose end of the pull-line (did not relegated function to a foot this time) and adjusting the pull-line through the bends to make it taut.
One hand assisting the tightening and alternately holding on to the wing.
I don't have another hand to hold the actuating arms stationary, I relied on the servo's holding power instead, quite risky.

Then a short test and found that the wing actuating mechanism was not functioning properly: the centering is very bad.

I ripped it out, the aluminium bearings were jammed with white glue, the slit tube connecting the internal perpendicular horn was loose.

I'll have to do another wing actuating mechanism.
This time with longer actuating arms, straighter connecting rods, made from thinner wire (that's the only thickness I can form an eyelet), maybe replace the 3mm aluminium tubing bearing to some smaller plastic sheath. I don't think I want to solder the internal perpendicular horn and will just superglue it with short 3mm aluminium tubing.

Flying Flea, insufficient throw at the main wing.

The flea is dependant on the wing incidence of the main wing for attitude of the plane.
If hooked up as it is, I think the change in angle of attack of the main wing is insufficient.
Yesterday, I thought of moving the lug points closer to the wing pivot.
I could do a temporary lug with temporary pushrod to see how the flea flies.
An alternative is to extend the actuating arms.

The actuating arms are approx. 17mm long and the throw is approx. 10mm.

The distance between wing pivot point and lug points is approx. 65mm and the distance between wing pivot point and trailing edge is approx. 90mm.

If I want the throw at the trailing edge to be 20mm, then the actuating arms should be approx. 24mm.

I don't fancy additional lugs, I don't fancy changing the actuating arms, so maybe I should extend the actuating arms instead.

A bit of nylon fishing line to form an eyelet at the end of 25mm long carbon fibre rod of 1.5mm diameter, heat shrunk to existing actuating arms might be good enough.

How long should my wing pull wires or pushrods be? How to make it adjustable? How much of wing incidence when neutral?

The first thing to answer should be the fore wing incidence, relative to the rear wing. Do I want the rear wing to exert a downward depressing (stabilising) force like a normal flat plate horizontal stabiliser or to utilise the rear wing to provide some lift as well? Since the rear wing is already a lifting section, I choose that it should contribute to the overall lift. So if it is going to lift and I don't want the front wing to underwork either, I shall arrange 0-0 degree decalage (if you consider treat both wings to be a set of biplane). Motor is also at 0 degrees, so increasing the power to the motor should accelerate the model causing both wings to increase lift due to increased speed and minimal loss or correcting force.

With everything at zero degree, how shall I have adjustable pushrods/pull-lines? If it is pushrods, I could use collet, I could take use heatshrink (which 'ought' to be tight enough but I have no way of knowing until I try), or I could just have a kink. If it is pull-lines, I could use loops and aluminum tubing.

I think I could also just use one actuating end with kinked wire pushrod to determine the length after flying it.  Then when it is flying ok, to fit the other actuating arm extension and to replace the kinked wire with pull-lines, and if found that push rod is required, to heat shrink on a carbon fibre rod to one of the pull-line.

Or shall I just install 2 actuating extension arms and use pull-lines without adjustable feature? Relying on quick and stable jabbing of the transmitter?

Stringed up Pou du Ciel

There are 3 stringings.

The first is the " /\/\| " configuration when viewed starboard side.
This braces the top wing, giving it lateral restraint.

The second is the " /-\" configuration, again when viewed from starboard side.
This braces the planforms of the wings.

The third and final stringing is the "\/-\/" configuration when viewed headlong or from tail view, connecting the incidence horns.

During the first stringing, while tightening the lines and preparing to lock it down with 3mm aluminium tubing, the end line pulled through the pvc lug.
So it is determined that 1) the lug ends are the weakest point, 2) the anchoring of the lugs is strong enough, 3) the line is strongest.

To repair this torn lug, I could 1) replace the lug, 2) reinforce the lug.
To keep things fast and simple, I cyano'd a small washer onto the lug, should be strong enough.

First stringing done, I admired the handiwork and found that some lugs are lifting the tracing paper covering. This won't do, the tracing paper is relatively weak and could give way easily. So, I poked holes around the lugs, through the paper/tissue and injected superglue (foamsafe of course). A bit of kicker and hold it in position until the lugs, or rather the underlying paper/tissue don't come loose.

Initially, I thought the 2nd stringing should come before the 1st stringing because the line has to pass through the main wing's lug before the 1st stringing. Then I figured that they are non-interfering, and I should get the most part of the stringing done first, that is, the one that uses the longest line.

For simplicity, I did not follow the full-size stringing practice which entails individual lines (of which I perceive). Instead, I used a continuous line for the first stringing, relying on friction to hold in position, which means I can adjust the wing's lateral tilt easily, and only 2 ends in the whole 1st stringing exercise to contend with.

It seems like I should do the 3rd stringing before the 2nd stringing, even though 3rd stringing is 'shorter' because it seems that the throws I am getting from the wing actuation horns are small and will not change the incidence of the main wing by more than a few degrees.

With such short throws, the incidence of the main wing can only be controlled to a few degrees, how would I ensure sufficient control authority?
Assuming I want -5degrees and +10degrees, it is a total of 15 degrees. The servo operates say 60 degrees. On account that somehow my wing actuation horn travels only less than 10mm, I think that the 'original' wing pull locations at the main wing is too far back.

I should do some measurements on the throw I am getting from the wing actuating horn/s. Maybe I'll just put in a pushrod and connected to a point on the wing much closer to the pivot point of the same wing.
For this temporary pushrod, how shall I make it adjustable?

Completing the Flying Flea

Here's the main wing from pink foam.

 

 Here it is with the tips sanded, ready for sawing for the polyhedral. The bow is actually the wooden spar for the main wing.

Pasted tracing paper over the wings and fuselage.







Result is not good, I re-learned the knowledge and practise the technique:

• to glue only small sections
• to glue on edges, leaving centre bare

I think it ought to be better if I had used pre-wet tissue on full glue surfaces but I have not got around to experiment it because I couldn't figure out how to 'hold' the pre-wet tissue. Also, I have no spray mister, I was using a 2" brush.

Then I fabricated the rudder horn of 5mm carbon fibre strip and pvc report cover sheet and linked up the pushrod/s (one actual, one dummy) and used more pvc report cover sheet as hinges for the rudder and cyano'd the rudder in placed.

Turned-on the transmitter the rudder functions but the wing rocking mechanism is not working. I had to aid the elevator servo a bit by bending the mechanism until it came loose enough to operate.
Not too good though, because the centering seems to be lousy.
Next time I ought to devise access to the servos.

Last Sunday, I went to the flying field and did some spray painting with  a $2.90 rattle spray can. Result is not good, the nozzle clogged and the paint came out in splutters. So I ended up with sprayed uppers of the wings, top and sides of the fuselage.
This leaves the bottom of the fuselage partly painted and both undersides of wings unpainted.

Never mind.

I used some red coloured packing tape for the fuselage bottom and decide to leave the wings alone.

In the evening, while listening to the National Day Rally, I fabricated the lug points of the wings, glued on the rear wing, glued on the cabane structure to the front wing and glued in turn, the cabane structure to the fuselage.

Now I only need to string the whole flea together.

Should I use more 3mm aluminium tubing, or should I use heat shrinking electrical tubing to afix the nylon lines?

Wing Construction

The Pou du Ciel employs biplane wing with much stagger and not much height difference. There is no horizontal stabilising tail-like surface and no elevator.

To make the lower and rearward wing, I used a profiled foam blank.   The blank is a bit shorter than the required span, so I added 1/16" balsa wingtips.

Foam blank with balsa tips, port side is snipped to approximate shape.

Foam blank to the correct chord and planform shape.

Sand to airfoil.

Polyhedral to simulate the curved wing.

 

Remaining to do:

• anchoring system for the flying wires;
• more chord lines? perhaps;
• covering and finishing.

Pou du Ciel, the Flying Flea

I've had the tail wheel assembly done previously.

And cut the 2 fuselage sides and 1.75" wide former blanks out of 1/16" quarter-grained balsa sheet.

Fabricated the twin control horns from 3mm aluminium tubing, abt 1.5mm wire and abt 0.8mm wire. Assembly with aluminium from the tubing and BSI superglue.

Then over the weekend, 1/16" sheet and strips (from offcuts naturally) and carbon fibre used to make the vertical tail assembly.





Ready for sanding.
Decided where and how I am placing the radio gear.





 Cyano'd the sides with cross grained formers (all 1.3/4" width)

 Formed the top nose with straight grained 1/16" sheet, wet formed in position to reduce the strain.










Marked and cutout where the motor will go.







 Installed the tested rc gear. The servo rails are balsa strips of 1/4" square (or 3/16", I don't remember).











This picture shows the battery tray, 1/2" gap.













Fabricating the wing pivot cabane strut, first by making the jig, then cutting off lengths of carbon fibre rods, 0.65mm pvc sheet and 3mm aluminium tubing. I figured that aluminium sheath will present greater surface area for later gluing.

 Here a picture of the cabane spot glued with the jig snapped off.






This is the completed cabane assembly.

Tail Wheel Assembly for mini-RC 'Le Pou du Ciel', aka 'Flying Flea'

Earlier on, I thought of grooving an end of the vertical aluminium tubing to fit over the horizontal tubing and then to epoxy them together. That, and/or to strengthen it with 0.65mm PVC sheet.

Last night, on a whim, I started to fabricate the tail wheel assembly for a mini RC flying flea. I may not finish the model, but it is the process that I enjoy. To groove the end of the vertical aluminium tubing, I will have to file/sand, and I don't have a small round file and don't fancy wrapping sandpaper over the tubing.

Instead, I sawed one end of the vertical tubing, splayed and flatten the two resulting ends, and curl them to receive the horizontal tubing.

I used superglue to glue the two tubes together.

I marked out the 1/2" diameter wheels from 1/16" ply.

Drilled the centre holes with a 3mm drill bit held in a pin vise.

Added the bushings made from the same 3mm diameter aluminium tubing.

Sand and assemble them to the aluminium T-joint.

Then I realised that the 1/16" wire has a bit too much slop and replaced the wheel axle with a 2mm diameter carbon fibre rod and retained the wheels with what else but small snippets of 3mm aluminium tubing lengths. In this photo, you can see the superglue on the T-joint and an end of the wheel axle and retainer. This is easy.

Connecting Points, Bits and Pieces

Ends of Pushrods (or pull rods)

The typical Z-bends, U-bends and L-bends are great if all that is needed are pin ends. For rods to end with eyelets, I came up with two solutions:

1. If the rods are 0.6mm music wire, the end doubled back on itself forms an eyelet; I use a 3mm length of 3mm dia. aluminium tubing to lock the end against the rod;
2. For 0.6mm to 2.0mm rod ends, use 0.65mm nylon fishing line doubled back on pushrod and secured with 3mm tubing;
3. If flat strips, then 0.18mm PVC or 3mm tubing can be used, choice depends whether you want the hole flat or vertical.

Connecting Bits and Pieces

The intention is to use them in small RC aircraft using readily available material that are easy to work with, e.g. 0.18mm PVC sheet and 3mm diameter aluminium tubing.

1) Cabane Truss with Pivot

E.g. Pivoting fore wing of the Pou du Ciel

2) Rudder Horns

Pull-Pull horns

3) Bracing Lugs

For wings needing bracing attachment points

4) Twin Tail Wheel Bracket

Twin wheel assembly for Pou du Ciel

Compound-Curved Wing Tips

Pou du Ciel has interesting compound-curved wing tips, how does one go about fabricating it?

Foam Wings

1. Trim the airfoiled foam blanks to planform and sand the wing tips to profile.
2. Make a wing tip jig to each tip curvature, marking on the jig the planform of the wing tip. A concave jig is better than a convex jig because it is easier to push at the centre then simultaneously at both ends, and in the case of foam wings, easier to see and sand the saw cuts of step 3.
3. Saw 3/4 of the way through each rib position. Offer up to the wing tip jig, if the saw gap is insufficient for the curvature, sand with knife file.
4. Bend and cyano. 
5. If the 2 pairs of wings are to be covered with tissue, then I'd say that they are sufficiently reinforced.

Built-up Wings

1. Do up left and right wing tip jigs as per step 2 under 'Foam Wings'.
2. Cut the shape of wing tips in 5mm foam, undersize them to allow for the thickness of the leading and trailing edges. 4 will be needed, one for each wing because I observed that the wing chord of the rear wing is shorter than the front wing's. These are our wing tip formers.
3. Bend and glue the wing tip formers to the wing tip jigs.
4. Soak 4 or 6 or more 1/16" square strips in water.
5. Ease the strips into position against the wing tip former and on the wing tip jigs.
6. Starting at the base and going towardes the tip, spot cyano the strips together.
7. Excess to be trimmed off.

Then again, the tip proposal for built-up wings seems to be too much work and over complicating.

If the spars are made with the curved dihedral, why not just do up a normal tip? So long as the wood sections are small enough, they should be able to be nudged into position. Any cracks, just fix it with CA.