4
9.
W
A
RNING:
Some of the par
ts in this kit are made
of fi
berglass
, the fi
bers of which ma
y cause e
y
e
,
skin and respir
a
tor
y
tr
act irr
itation.
Ne
v
e
r b
lo
w
into
one of these par
ts to remo
v
e
fi
berglass dust, as
the dust will b
lo
w
bac
k into y
our e
y
es
. Alw
a
ys w
ear
saf
ety goggles
, a par
ticle mask and r
u
b
b
er glo
v
es
when g
rinding, dr
illing and sanding fi
berglass
par
ts
.
V
a
cuum the par
ts and the w
o
rk
area thoroughly after
w
o
rk
ing with fi
berglass par
ts
.
W
e
, as the kit man
uf
acturer
, pro
v
ide y
ou with a top
quality
, thoroughly tested kit and instr
uctions
, b
u
t
ultimately the quality and fl
y
a
bility of y
our fi
nished
model depends on ho
w y
ou b
u
ild it;
theref
ore
, w
e
cannot in an
y w
a
y guar
antee the perf
o
rmance of
y
o
ur completed model, and no representations
are e
xpressed or implied as to the perf
o
rmance or
saf
ety of y
our completed model.
Remember:
T
a
ke y
our time and f
o
llo
w the
instructions to end up with a well-b
uilt model that
is straight and true
.
DECISIONS
Y
OU MUST MAKE
This is a par
tial list of items required to fi
nish
this
model that ma
y require planning or decision making
bef
ore star
ting assemb
ly
. Order n
umbers are pro
v
ided
in parentheses
.
ENGINE RECOMMEND
A
T
IONS
As specifi
ed on the front co
v
e
r of this instr
uction man
ual,
the
T
op Flite B-25J ARF is intended f
o
r twin .70 f
our-
strok
es or .46-.50 tw
o-strok
e
s
. There isn’t m
uch more
that can be said other than it is unnecessar
y (as w
e
ll
as inadvisab
le) to o
v
er
po
w
e
r this model with larger
engines
. Engines in the specifi
ed r
a
nge will pro
v
ide
more than enough thr
ust to fl
y this model in a scale-lik
e
manner with plenty of e
x
tr
a po
w
e
r to perf
o
rm
e
v
asiv
e
maneuv
ers if the situation ar
ises
. Bottom line is with
tw
o-strok
e
.46’
s or f
our-strok
e
.70’
s y
o
u’ll fi
nd
y
o
urself
cr
uising around at half-throttle most of the time
.
RETRA
CT
ABLE LANDING GEAR
Y
o
ur B-25J Mitchell ARF ma
y be assemb
led with the
included fi
x
e
d landing gear or retr
actab
le landing
gear
. If fi
x
e
d landing gear is used, no additional items
will be needed to install the gear
. If installing retr
acts
,
this model is designed f
o
r Robar
t pneumatic retr
acts
.
F
o
llo
w
ing is the complete list of items required to
install the Robar
t retr
acts:
❏
Robar
t #TFB25
T
op Flite B-25J ARF pneumatic
retr
actab
le main landing gear (R
OBQ1624)
❏
Robar
t #157VRX Large-Scale Delux
e Air Control
Kit—includes pressure v
essel, air line tubing,
v
a
ri
ab
le-r
ate air v
a
lv
e
,
T
-fi
ttings (R
OBQ2305)
❏
#190 Air Line Quic
k
Disconnects (R
OBQ2395)
❏
Standard siz
e
ser
v
o
to oper
ate air control v
a
lv
e
Additionally
, a hob
b
y
can of compressed air such
as Hob
bico Duster
™
(HCAR5500) will be helpful
fo
r cycling the retr
acts dur
ing assemb
ly and setup
without ha
ving to connect the gear to the air control
v
a
lv
e
, fi
ller and air tank bef
ore it is ready
.
An air pump will also be required f
o
r fi
lling the on-
board air tank when y
ou get to the fi
eld and it’
s time
to fl
y
. The Robar
t Hand Pump & Gauge (R
OBQ2363)
could be used, b
u
t will require consider
ab
le time (and
eff
o
rt!) to fi
ll the tank.
Instead, w
e
recommend an
electr
ic hob
b
y
air compressor (with a pressure gauge).
What w
e
use in our R&D shop is simply a small 12V
bicycle air compressor
.
The po
w
e
r cord ma
y ha
v
e
to
be con
v
e
rt
ed from a cigarette lighter connector to
alligator clips or something that can be connected
to y
our 12V batter
y.
Connect Robar
t’s air fi
ller to the
compressor with a length of Robar
t air line
.
RADIO EQ
UIPMENT
If fl
ying the B-25 with fi
x
e
d landing gear se
v
e
n
channels will be required;
one channel f
o
r the
ailerons
, one f
o
r ele
v
ator
, one f
o
r each engine
, one
fo
r the r
udder
, one f
o
r the fl
aps and one channel f
o
r
the nose steer
ing ser
v
o
. The engines could be link
ed
with a
Y
-har
ness
, b
u
t it is recommended to link the
throttles electronically via mixing in the tr
ansmitter
.
Then, the throttles can be
“decoupled”
using a s
w
itch
on the tr
ansmitter f
o
r star
ting and tuning the engines
individually
. It is also recommended to link the r
udder
ser
v
os and nose steer
ing ser
v
o
electronically through
mixing in y
our tr
ansmitter so the nose steer
ing ser
v
o
can be tr
immed separ
ately from the r
u
dders
.
If installing retr
actab
le landing gear eight channels
will be required, with an additional standard ser
v
o
to
oper
ate the air control v
a
lv
e
.
Regarding ser
v
o
s
, the ailerons
, fl
aps
,
nose
steer
ing
and air control v
a
lv
e ma
y all be oper
ated with standard
ser
v
os (such as Futaba S3003—FUTM0031).
A
stronger ball bear
ing ser
v
o
with no less than 50 oz.
in.
of torque (such as the Futaba 9001—FUTM0075)
should be used on the ele
v
ator
. T
w
o mini ser
v
o
s with
a torque r
a
ting of at least 35 oz.-in.
(such as Futaba
S3115—FUTM0415) are required on the r
udders
.
Note:
K
e
ep in mind that the standard ser
v
o
recommendations f
o
r the fl
aps and ailerons are the
minim
ums
. Higher-torque
, ball bear
ing ser
v
o
s could
be used f
o
r more fl
ight
precision.
The f
o
llo
wing ser
v
o
e
x
tensions and
Y
-har
nesses w
e
re
also used in this model.
See the diag
ra
ms on pages
48-49 that sho
ws where all the e
x
tensions are used.
