It results from the crossing of the Schiumini wing (cf Italian site of Barrone-rosso), probably inspired from the ZAGI, and the principles of engines fixing tested on the electric die-hart . The wing is hot-wire cut in two pieces, either with a CNC machine if you built one of them, or with more traditional methods. I cut out this wing before building my CNC by using only one gauge and a system with pulleys which makes it possible to twist the wing automatically ...
geometry:
Its geometry is that of a sweptback wing. The selected scale is adapted to the size of the polystyrene bread: 123 cm. It is cut in yellow extruded polystyrene. The other values characteristic of the wing geometry are as follows:
|
root (cm) |
Ce |
31 |
|
salmon (cm) |
Cs |
12,5 |
|
half span (cm) |
b |
61,5 |
|
arrow (cm) |
a |
16 |
The profile used for the wing is a self-stabilizing TSAGI 12% of relative thickness to ensure a good rigidity while having a correct penetration in the air. The co-ordinates of this profile are in file TSAGI12.DAT
The two profiles for root and salmon are identical (with different sizes...). The wing is twisted, the trailing edge end of salmon is higher than that the root's one. The negative twist thus obtained is of 6°. It may be juged too much, but the wing flies perfectly with this value!
The elevons have a 3 mm thickness, it is thus appropriate to remove the end of the trailing edge by cutting out it to 3 mm thickness (hot wire cutting ).On my wing, the salmon width after cutting is 11 cm, the root remains almost at 31 cm
It is necessary to cut out in a 3 mm coroplast (alveoled corrugated plastic) a central gauge with the shape of the root. The flutes will be in the direction of the cord parallel with the cord. This gauge is stuck with double sided adhesisive tape on the root of a wing core, then the second core is also stuck to constitute the wing.
the radio gear:
I equipped this wing with standard GRAUPNER 501 servos, no problem with the weight ! The wing is dug to make a soft nest in which the servos are strongly embedded. The exact location of the servos is of few importance; dig the wing at the place where the profile is thickest! Think of positionning the servos so that the linkage is perpendicular to the trailing edge. A small hole made with the cutter and the screwdriver will allow encaster the servowire before covering with the Scotch tape.
This unit is covered with the glass fibered adhesive tape on the two sides while beginning by the trailing edge. The junction of the two cores will be reinforced by a second layer of adhesive tape.
The nose of the wing is cut over approximately one cm (to bring closer the engine). Note that the measurement of the centre of gravity must be made as if the nose were not cut.
The elevons are made off 3 mm balsa They measure 57 cm length and have a trapezoidal shape (4,5 cm at salmon and 2,5 cm in the center). They are coverd with plastic tape then fixed with BLENDERM adhesive tape (3 euros in pharmacy) divided over the length directly on the roller.
Clearances to be envisaged are as follows:
- depth: +15mm/-10mm compared to the neutral
- direction: +15mm/-10mm compared to the neutral
- mixing 50% ailerons/profondor. Which is perfectly convenient for Aeropic's electronic mixer ...
- neutral: elevons slightly pulled up (see photographs)
The remainder of the equipment includes:
- a speed 400 6 V
- an adapted propeller (6x3 " with folding blades)
- a 7 elements battery (I use the SANYO 650mAh, the wing should fly with a SANYO red 1000 mAh but I did not test...)
- a spedd variator with BEC and brake (Easy Line 3000 of KONTRONIK makes the deal perfectly).
engine mounting:
The central rib will be used as driving support. Another plate
of coroplast (cells longitudinally) will be set under the wing
with the double sided adhesive tape, then covered with the fiber
glass adhesive tape over the entire length, you just have to push
2 sections of 20 cm carbon stem in two cells separated by 2 cm
(leave 5 holes of free between the two stems) to make the
horizontal cradle of the engine support.
Finally a stem of 20 cm is threaded in one of the cells of the
central profile to finish the engine support. The engine is fixed
with steal wire : no comments...
battery support:
Take your battery and roll upa rectangle of coroplast plastic around the accumulator, the flutes parallel to the length of the pack. You should cut the plate so that the plastic comes free in and out without play. The length of this plate must be approximately 14 cm (including 2 cm of legs) for a battery of 650 mAh.
Remove the four corners of this part over approximately a 1,5
cm length to preserve only the part in the prolongation of the
face punt of the pack of accumulators.
With the same aim, but also to ventilate the accumulator and to
facilitate its installation, detach with a cutterr a leg on both
sides of the accumulator. (cf photographs which are surely clearer
than my explanations...) The four legs obtained will be used to
fix the whole under the wing with double sided tape on all
surface.
Centering ranges between 17,5 and 18 cm cm of the nose. If you modified the length of the cord, you can recompute the position of the Center of Gravity using the Excel file aile_ORFEO.xls Proper centering is obtained while making slide the accumulators in their housing.
NOTE: I repeat for those which read too quickly... the measurement of the centre of gravity must be made as if the nose were not cut .
body:
The body is cut out in a small Schwepps plastic bottle. Just cut the neck of the bottle, remove the bottom and release two forms of profile coarsely as you can see on the photograph below:
Thread this cap on the engine and the wing, the lower part comes to cover the battery support, the top will be taped flat on the extrados face, it hides the whole wires as well as the receiver and the variator.
rudders:
It is necessary to cut out two rudders in a plate of 6 mm DEPRON (or coroplast plastic, even of balsa). They will be stuck with double sided adhesive tape to the end of wing and will be ensured by a adhesive tape band on the outside of the rudder and the lower part of the wing.
The form of the rudders is free. The picture above gives you an idea of the size which does not have either, great importance...
flight:
ORFEO appears very very pleasant to control. The motorization is correct and makes it possible to hold 5 to 6 minutes in flight even more if you are lucky ... The wing climbs well face to the the wind and can fly without motor at the slope.
Generous surfaces of elevons confer a significant rate of roll to him, ORFEO passes the barrels in a few seconds.
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The loops ask for a small catch of speed, the wing restoring very well its speed, the curve is gracious. |
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back flighing is a piece of cake, it is necessary to slightly push to hold the wing flat. |
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It is not this wing that destroyed the AZF chemical plant in Toulouse ...
