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.