necessarily the right way, but it worked for me. Don't
blame me if it doesn't work for you!
First, the main section of fibreglass for the radio
equipment has to be removed. I used the Dremel with
router bit to do this, followed by a sanding stone to
make the edges nice and smooth. It’s worth spending a
few minutes working out where everything is going to
go before you start cutting! Also, bear in mind that
the battery will have to move back slightly to
accommodate a lead casting right down in the nose.
I wanted to keep my model as light as possible so I
mounted the two v-tail servos as far forward as I
could get to eliminate the need for a lot of nose
weight. This had a slight complication: you have to
remove the front servo to get the battery in and out.
This was achieved by making the ply bearer removable.
It’s screwed in from the sides of the nose using
countersunk screws. These screws are covered when you
slide the nosecone on. The battery is held in place by
this bearer. The other two bearers are glued in
position using epoxy and micro-balloons. Offsetting
the servos slightly from left to right helps the horns
and clevises clear the nosecone. The receiver and
switch are mounted behind the servos with easy access
for changing the xtal.
The pushrods are made from two lengths of carbon tube.
I dripped epoxy down the tube then pushed in threaded
rod for the clevis to connect to. This was done at
both ends. Make sure that the threaded rod is clean
and has a few barbs filed into it before gluing.
First, epoxy or screw the ball links to the posts on
the ruddervators.
removable. I opted for removable to aid
transportation. This proved to be a little easier than
I had imagined by having two machine screws going
through the fuselage into nuts mounted in the v-tail.
First of all, drill two holes through the fuselage
where the tail sits. These have to be just big enough
to put an aluminium tube through. The tube is used to
sleeve the two machine screws and to stop the fuselage
from collapsing when the screws are tightened. I used
M3 machine screws but I think M2 would have been
better. Next, epoxy two tubes in place making sure the
rim of the tube is flush with the outer skin of the
fuselage on both sides. Leave it to dry properly
before doing anything else.
The next thing to do is make some barbs and/or grooves
on the nuts. Make sure you use the domed nuts to stop
any epoxy getting onto the threads. I used a cut-off
disc on the Dremel to make lots of cuts on the nuts to
aid the fixing (the epoxy runs into the cuts).
Next, put some electrical tape on the base of the tail
and offer it up in the correct position and tape it in
place using masking tape. Push the screws through the
tubes to mark on the electrical tape where they exit.
Now remove the tail.
You need to make two holes where the electrical tape
has been marked. They need to be larger than the nut
so that a ring of epoxy can work its way around the
nut. You will find that the tail is hollow and
requires a ‘wall of epoxy and micro-balloons’ to be
made in the holes. This is to create an ‘inverted
bucket’ shape to put the nuts in and to stop the epoxy
holding them in place from running away.
Next, put the screws through the tubes and tighten on
the nuts. Don’t make them too tight for the moment.
Position the tail once again to make sure that the
nuts go into the tail. If all is well it’s time to
epoxy the nuts in.
Turn the v-tail upside down and put a blob of epoxy
and micro-balloons in one of the holes, just enough to
fill about one half of the bucket. You can then
position the fuselage over the tail, making sure it
all remains level. Make sure the tail is in the
correct position and tape in place. Now, be patient
and wait for the glue to cure completely.
When the epoxy has set, unscrew the screw that you
have just worked on. What should happen is the tail
can be removed leaving the nut glued in position. Now
all you have to do is fill in the remaining part of
the bucket with neat slow-set epoxy (as it's thin).
Don’t use any micro-balloons for this as it’s
important that the glue seeps into the grooves you cut
on the nut.
Now do the same thing with the other nut, making sure
you secure the tail this time using the first screw.
When done you will end up with a lovely removable
tail. Easy! All you have to do is pop off the ball
links and away you go...
You can have a 2 or 4 servo wing. I chose to have 2
(aileron only – no flaps). Baudis do not provide
fantastic instructions on how and where to mount
servos, so here are a few tips.
back from the trailing edge at a distance of 230mm
from the centre. This seems to vary slightly on each
model so be careful. I used a Dremel with router
attachment to cut the holes as close to the spar as
possible. This was done by cutting a smaller hole in
the centre of where I thought the servo should go,
then looking inside to check that the spar was where I
thought it was. I then used a jig made from thin mdf
to route out the correct size, making sure that I left
‘rounded off’ corners to stop any future splitting.
There seem to be various ways to mount the servos. I
used Hitec HS125’s and epoxy'd them in place as per
Kevin Knewtons instructions
(http://www.knewt.com/planes/servo.htm) including
placing a sheet of lightweight glass on the wing
surface first. The epoxy method has worked well for
me, but make sure you have electrically centred the
servo and screwed the horn on before gluing! I also
made some wedges that fit around the servo cut-out to
strengthen the surrounding skins. These are made from
balsa and glued in position. The servo covers can be
placed in the correct positions and taped in place
using Diamond tape. I sprayed mine with acrylic paint
to match the wing colour.
The electrical connections from the wing the fuselage
can be made in various ways from simple servo-lead
extension cables to multipin connectors. I used the
latter by epoxying the plug side of the connector in
the centre of the wing. If I ever build another
banana, I will not bother with this arrangement as it
was a lot of hassle for a very small gain of
convenience. I would use the green mpx multipin
connectors and have a fairly large hole in the bottom
of the wing and on the wing seat for the connector to
go. Don’t forget to use heat-shrink over the pins when
you have soldered the wires on (putting the
heat-shrink on the wire before soldering of course!)
and make sure everything is secure. You could 'pot'
the connections in epoxy for extra security if you
think it's necessary.
I used small brass control horns from South Coast
Sailplanes. These are fitted by drilling through the
aileron surface, putting a blob of epoxy mixed with
micro-balloons in the hole, then placing the brass
outer post in the hole. Secure it with masking tape
from above and let it set. Make sure the brass in nice
a clean and make some barbs on it using a file or
Dremel cut-off disc for the glue to stick to. The
threaded control horn can then be screwed in to the
required height. Wrapping a little ptfe tape round the
thread stops any play. The linkages can then be made
from a short length of threaded rod with a metal
clevis on each end. Once again, I used a little ptfe
tape to secure the threads.
And
that's about it. I cast a lead weight to go down
the nose. The CoG is currently set at 68mm back from
the leading edge and the auw is 661g. It appears that
the CoG can be anywhere between 65mm and 75mm
depending on personal preference.
Flying this little rocket is great fun! Be warned
though. Look away for half a second and you'll lose
it!
JH 2006