The Fletcher is an F3B glider, fully moulded, developed by Frits Donker
Duyvis, winner of the European championship in 1994. This glider is the
result of an extensive aerodynamic study using computers to create a
new airfoil section based on two well known sections: RG14 and S7003.
Refer to QFI for more details about this aerodynamic aspect.
The Fletcher kit is manufactured by Jet & Speed Models, in the
Netherlands. The delivery time is about 3 months, and you pay when
you order. It comes in a surprising small box, compared to the
dimensions of the glider. This is because the center panel is shorter
than usual F3B gliders, and the fuselage isn't assembled (like the Calypso
, you have to fix the keel during the construction).
The Fuselage
is made of fiberglass, kevlar and carbon for the fin. This fuselage is
very thin and the space for the radio equipment is small. Olivier's one
had grey spots on one side between thewing place and the rudder,
perhaps a gelcoat problem. On the fuselage, you have all the work to
do. The control commands are not provided. Only the bellcranck, moulded
in fiberglass and carbon including steel, is part of the kit, but is too
short. It should be two centimeters longerto be mounted as described in
the building instructions. The rudder is nice and very light.
The tailplane uses fiberglass and kevlar for the hinge. I
found this hinge a little bit hard to manipulate. So, be careful
with the choice of the elevator servo. The extremities of the tailplane,
at the end of the hinge is very fragile, because there is no balsa, just
skin. It would be better to reinforce this part with micro-balloon. The
Tailplane is fixed on top of the fin with a screw anda nut. I don't remember
if they are provided, but the nut has to be install in the fin.
The wings are in three parts, with carbon skin. The control surfaces
have been moulded separately. Unfortunately, this is where the problems
start... Both flaps are too long compared to the center panel, so they
have to be re-cut to the right dimension, but this point is not so
serious. The critical point is that they definitely don't fit correctly
on the wing. I don't know if they are too thick, instead I would say
that they are malformed (curved vertically). The consequence is that
the tape you use as a hinge, is not sufficient to hold in place the
control surface. In the middle of the control surface, there is a
difference of 1 millimeter! The center panel includes a ballast tube
just behind the carbon spar. On my exemplar the tube was missing...
To finish with problems, on the tip panels, at the end of the ailerons,
the trailing edge is pinched, especially on one panel (It's true that
the section is very thin here). Servo wires are pre-installed in the wing.
Unfortunately, the review stops here because we sent back the
two gliders, listing the different problems encountered (and described
above). But, based on a discussion with several pilots from the F3B
French Team, the Fletcher is an efficient F3B glider, especially in
distance.
In conclusion, the Fletcher could be a good competition glider,
but the kit is not up to the original design from Frits Donker
Duyvis (The Fletcher used by Frits was moulded by himself, so
is not from a kit...).Compared to competitors (Calypso, Ellipse 1
or 2, ...) the Fletcher is poorin terms of Quality/Price ratio.
... Last minute ...: It seems that Jet & Speed Models have
made some modifications to correct the different problems encountered,
and is making new aluminium moulds for a new version. At this time, I'm
not able to give more information about the current quality of the kit.
So, wait and see...
Any comments, suggestions ? Des commentaires, suggestions ?
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R/C Soaring Magazine.