Sabre 2015 - 25th Anniversary
SABRE is a simple lightweight thermal soaring glider with an excellent
performance. It is simple to build and its rectangular wing guarantees
benign stall characteristics. It’s a versatile model - the prototype
has even been used to take aerial video of Milton Keynes using a mini
digital camera - see below. Sabre uses standard size servos and radio
gear operating rudder and elevator. Purchase
the Sabre Plan RC1626 from MyHobbyStore.
Above: Sabre prototype 1
Abbove: "Closed-loop" control system modification worked extremely
well in improving lateral control.
21st Anniversary
Plans for the Sabre were published in RCM&E magazine in 1990. In
2011, to mark the 21st anniversary of publication, Sabre prototype number
one was overhauled and converted to electric power.
The conversion is relatively straight forward. An aperture is cut in
the balsa nose block as far back as the first fuselage former. A 2.5mm
plywood firewall is glued to the former such that it gives the motor
around 3 degrees down-thrust relative to the wing chord line. The motor
is screwed directly to the firewall.
The equipment within the radio bay is repositioned. The servos are
moved back and the second fuselage former is cut so that a 1200mAh 3s
LiPo battery and speed controller can be accommodated. 2.5mm packing
under the tailplane leading edge reduces longitudinal dihedral and completes
the conversion.
Why convert the Sabre to electric power?
Launching a thermal-soarer using a bungee is a relatively simple operation,
however, there can be drawbacks - as illustrated in this video* - and
these make an electric conversion an attractive proposition.
Converting the Sabre to electric power
This video* outlines what is needed to convert the Sabre to electric
power. Details of the system are given below.
motor: 1450Kv Brushless Outrunner
prop: Ripmax 8.4 x 4 folding prop
battery: lipo 3s 1200mAh
full power static test: 145 watts, 12.8 A, 11.1 volts
motor down-thrust = 3 degrees,
longitudinal dihedral reduced by adding 2.5mm packing
under the tailplane leading edge.
Electric Sabre in flight
The finished article. Electric Sabre is as easy to fly as its pure-glider
counterpart. It climbs quickly to height for some relaxing thermal-soaring
or wafts around lazily at lower altitudes on reduced power settings.
Aerial Video
A rather crude mounting platform was all that was required to add a
digital camera to our Sabre thermal soarer back in 2003. It proved to
be an easy setup, not least because the model's centre of gravity and
all-up-weight were maintained simply by removing existing ballast. The
installation worked well and had no adverse effect on the model's handling.
The aerial video embedded here was taken over Campbell Park,
in the Centre of Milton Keynes.
Like all gliders in the Armada range, simplicity is the key note for
the Sabre and conventional balsa wood construction is employed throughout.
Note: pdf INSTRUCTIONS are available -
just "contact us"
for a copy.
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