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.