It’s also a perfect size to transport it around
in a rental car during the days before and
during the competition. To complete this
Albatros we need at least 8 servos, a good
power unit for the radio system, a thrust
tube and a turbine giving between 120 and160 Newtons of thrust.
As I had decided to go for a fully electrical
system, getting rid of anything pneumatic, I
added 3 servos for the landing gear doors,
and another two for the ventral airbrakes.
This latter can be operated by just oneservo, but as I will explain later in this arti-
cle, I decided to go for two, so a total of 13
servos of various sizes were installed in my
L39: we fitted Futaba BLS175SV servos on
all the control surfaces and on both main
landing gear doors, a Futaba BLS153 on
the nose landing gear door, two Futaba
BLS153’s on the airbrakes and a Futaba
S9550 low profile on the steering. I decided
to power the system at 7.4v, which is per-
fect for the 175SV as it’s a HV servo, but
not for the BLS153 and the S9550, as
they’re not HV, but the solution is quite sim-
ple: for each of these servos I added a
PowerBox Systems Linear Voltage
Regulator which limits the voltage to
5.3V....problem solved.
Having mentioned PowerBox, we installed
a Mercury SRS, together with two Futaba
R7008SB receivers connected via the
SBUS port, powered by two 2S 4200mAh
Li-Po packs. When selecting the turbine I
had no doubts: ever since 2011 I have
been flying with Evojet turbines, and to say
that I’m a happy customer is an understate-
ment: I have two 160VX and two 220EX,The turbine mounts and intake duct are installed at the factoryFEI-BAO L-39 1:4.8
A close-up of the fuselage joint The canopies are side hinged at the factory as per the full size,and they’re kept closed by a normal spring loaded hatch catchThe ventral airbrakes are hinged on a plywood former that we glued into place with resin. We decided
to control each airbrake with its own servo to have more precise and accurately matched movementsL39_Layout 1 08/03/18 13.07 Pagina 3