vq model p-61 black widow arf 90 rc
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Piccole Ali
Aeromodellismo dinamico online
2009 Piccole Ali – Stra’ (Venezia) - Italia
AEROMODELLO RADIOCOMANDATO
RADIO CONTROL MODEL
NORTHROP P-61 “BLACK WIDOW”
VQ MODEL NORTHROP P-61 “BLACK WIDOW” ARF 90
Apertura alare / Wing span: 2260 mm
MOTORE A SCOPPIO / GAS POWER
2-Tempi / 2-Stroke: 0.75 – 0.90 ci (X2)
4-Tempi / 4-Stroke: .90 - 1.20 ci (X2)
Produttore / Manufacturer: Distribuito in Italia da:
www.vqmodel.com www.piccoleali.it
www.piccoleali.it …passione pronta al volo !
2009 Piccole Ali – Stra’ (Venezia) - Italia
Il P-61 “Black Widow” fu il primo aereo Nord Americano ad essere progettato fin dall’inizio per il ruolo dicaccia notturno. Quando arrivo negli squadroni di combattimento, verso metà del 1944, gli obiettivi eranopiuttosto scarsi.
Northrop dovette impegnarsi notevolmente con il P-61 “Black Widow”, di molto il più importante contratto maiottenuto. Soddisfare le prescrizioni del committente per un velivolo con tre membri di equipaggio fu una delletante sfide affrontate dal team di progettisti. Per l’intero 1941 – a dire il vero, per tutto il conflitto- emerserocontinue variazioni ingegneristiche che ritardarono lo sviluppo del P-61. Le armi furono ricollocate, serbatoiaggiunti, superfici di controllo riprogettate.
Le consegne iniziarono nel Maggio del 1944 quando il 348^ Squadrone Caccia Notturno (NFS) ricevette iloro “Black Widows”. Il P-61 aveva una manovrabilità eccezionale, considerate le dimensioni, grazie agliampi flaps molto ben progettati.
Il modello
Avete adesso la possibilità di possedere e di pilotare un pezzo di storia dell’aviazione. Il modello è
sobriamente rifinito ed è di gran lunga la miglior riproduzione ARF del P-61 disponibile nel mercato.
Parecchia attenzione è stata dedicata al sistema di “flaps” uno dei punti di forza del velivolo. Si tratta di una
EDIZIONE LIMITATA, non perdete l’occasione ! Potrete inoltre arricchire il livello di dettaglio in base alle
Vostre preferenze.
Il modello è indirizzato all’aeromodellista con esperienza nel pilotaggio dei bimotori. Il modello non è adatto
come primo bimotore.
Caratteristiche generali
Robusta costruzione in balsa e compensato delle migliori qualità
Accurato rivestimento in speciale film polivinilico per maggior realismo della riproduzione
Alettoni/Spoiler completamente funzionali
Flaps funzionali
Prese d’aria in fibra (non funzionali)
Collegamento delle semiali per mezzo di tubo in alluminio per maggiore facilità di trasporto e montaggio
Naca motore in fibra di vetro già dipinte di fabbrica
Riproduzione IMAA Legal 89” (apertura alare)
Mitragliatrici (simulacro)
Predisposizione per i carrelli retrattili (opzionali)
Manuale d’assemblaggio passo-passo in italiano
Caratteristiche tecniche – VQ Model P-61 Black Widow ARF 90 RC
Apertura alare 2260 mmLunghezza fusoliera 1710 mmSuperficie alarePeso 8380 – 9280 gMotore a combustione interna Con elica bipala / 2-Tempi / .60 - .75 ci x2
Con elica tripala / 2-Tempi / .75 - .90 ci x2/ 4-Tempi / .90 - .120 ci x2
Motore elettrico ----Radio 6 canali minimo
13 servi minimo
Accessori inclusi
Cappottine abitacolo
Serbatoi
Ogive
Ricco pacchetto hardware
www.piccoleali.it …passione pronta al volo !
2009 Piccole Ali – Stra’ (Venezia) - Italia
Non incluso
Motori, servi, carrelli retrattili, colla, pilotini, tubo per la miscela
Prodotti correlati
VQ Model P-61 Black Widow ARF 90 “Lady in the Dark”
VQ Model P-61 Black Widow ARF 90 “Jap-Batty”
Motore ASP S91A RC
Motore ASP FS120AR RC
TwinSync by Wike RC: l’affascinante e realistico suono di due motori sempre sincronizzati…ed in più una
speciale funzione sicurezza
Carrelli retrattili ad aria compressa con gambe ammortizzate
Visitate il nostro negozio online / Visi tour webstore: www.piccoleali.it o scriveteci /contact us at:
info@piccoleali.com
Aeromodello radiocomandato / Radio Control Model
VQ P-61 ARF REVIEW
By Sam Parfitt (from www.rcwarbirds.com)
Page 1
Well, she finally arrived, along
with the retracts (retracts are
bought separately). Since I did
the VQ P-38 construction article,
Twinman suggested I do the
build article. The good news is
that he promised me twice the
salary that I got on doing the P-38
article! I just got a new laptop so
hopefully all goes well and
everything is loaded as planned.
She arrived in two boxes (one on Monday and the
other today). After Monday, I had visions of a lost box,
never to be seen again, but it finally arrived.
They came with no additional packing on the outside
but everything is well packed and secure inside and
all arrived in good order. The smaller box has only the
center fuse and canopies. The other box has the rest
of the goodies
The retracts were ordered from Mike
(VQ) and are Spring Air. The retracts do
not come with struts but the struts are
included in the P-61 ARF.
The first package has the manual and
decals (really stick ons).
The next package has the struts and guns. The
struts look very sturdy.
Next are the two booms.
Some people call it shelf
paper but I like it: lots of
detail and it doesn't
wrinkle in the sun.
Real nice gear doors.
Inside top view.
This picture shows the
gear doors.
Next out of the box are the cowls. Nice
heavy duty fiberglass.
As you can see, the OS FX .91's won't
have to be sticking out to kill the scale
look.
Here are the cowls and nose
cover along with my engines.
I'm using J-tec's JT-903MX
where the exhaust slants back
45 degree's so little will be
showing on the inverted engine.
Those small fuel tanks have to
go: they'll only give me about 5
minutes on those .91's!
The business end of the boom: plenty
sturdy.
Next out of the box are the rudders
(hinges included). Very light.
Construction of the rudders are all wood
(the entire ARF is all wood).
Don't know what those white things are
(drop tanks?) but there are about 6 of
them(hmmm; room for my fuel!).
All the hardware came out next:
rods,
engine mounts.
1" aluminum tubes for the wings.
More machine guns(!!!)
nuts and bolts packages.
Real nice gear door hinges.
Gear wires (pitch!).
No wheels but I believe it's 3" for
the nose and 3.5" for the mains.
Next was the center wing
(top view). With flaps (as
does the outer wings).
No weathering like on
the P-38.
Center wing (bottom
view). 2 access hatches
for the flaps.
Page 2
Next is the horizontal
stab. Very light(built up).
pre-hinged.
The outer wings are last. The
bottom one is the top view (you
can see the spoilers: cool). also
flaps and ailerons. The top one
shows the bottom view.
This is the box of 28 or so servos ready for my P-
61 (never have too many servos).
I'm using Hitec HS475HB. They're 76 oz torque for
6 volts. More than enough for flying this plane and
when at least 13 servos are needed, at 18 bucks
apiece,
saves a lot of money over more expensive servos
(I'm using a JR 8103).
For the low profiles needed for the spoiler/aileron
combo, I'm using Hitec HS-77 (also 76 oz at 6
volts).
I'm starting with the outer wings instead of
the center wing that the manual starts
with, because it has the spoiler and I had
to see how that works first.
The servo cover farthest away from the
wing tip is for the outer wing flap. I mark
each cover as I take it off with an arrow
showing which part is pointing to the front
and also its purpose. (Screws are already
holding the covers on: another nice
touch).
The servo mounts are already glued in.
Looks like they did that because they are
at an oblique angle to the cover and they
didn't want us to hose it up.
As you can see, the servo fits the mount
perfectly. The mount seems very secure
but I'm going to put some epoxy on the
mount anyway (just to make sure!).
I use a Dremel tool to drill the holes for
mounting the servo,
I temporarily put a thin piece of the servo
box flap between the servo and cover
while drilling the holes. This keeps any
contact with the plane so less vibration is
transmitted to the servo and possible
feedback to the receiver.
The pin hinges are glued into the flap and
glued into a block of balsa that slides into
a square hole in the wing.
Never seen this before but very ingenious.
The center cover is for the
combo spoiler/aileron
servo. This mounts in the
wing and not on the cover.
Here I'm using HS-77
(ordered two of them and
should be arriving in a few
days).
Another nice touch: spoiler
and aileron from one
servo. Watch when drilling
the holes that you don't go
through the top of the
wing. The only safe way
from keeping from doing
this is to put a small piece
of metal between the
mount and top of the wing.
Here's a picture of the spoiler in
the up position (cool stuff).
Next is gluing the flap to the wing.
This is how I did it to insure that all is
aligned and moves freely(you don't want
to glue these incorrectly).
I used masking tape to tape the flap so it is
aligned with the top of the wing.
I like to stick the tape to my leg first to
reduce it's adhesive qualities.
Use good 3-M tape and not stuff that's
been in the garage all summer.
This side view shows a nice smooth
transition from the wing to the flap.
There should be a very fine line between
the top of the back of the wing and the top
of the flap.
The profile picture shows that VQ did their
homework: the back of the wing isn't flat
like on most ARF wings.
Now that the top is aligned, put straight
pins into those blocks of balsa from the
bottom of the wing to temporarily hold
those hinges at the correct location. Now
remove the tape and insure there is free
movement down for the flaps.
Pins in the bottom of the wing
Tape removed.
If all moves freely, you can tape the flap
back up and wick thin CA between the
balsa blocks and wing. This should insure
you have no turbulence from large cracks
between the wing and flap nor any binding.
NOTE: I tried to move the spoiler up but it
wouldn't work. Found out that I must have
put too much CA on the flap hinge and it
glued the spoiler to the wing.
Easy fix: a razor blade cut it loose (only
about 1/4" long).
Put a piece of wax paper between the
spoiler and wing or put it in the up position
when CA'ing the flap hinges.
So far, I'm impressed with the design work of this ARF: Some people may think the price ishigh but all those fine details added thus far makes this a cheap plane.(HMMMM, for me to design and build spoilers: that will take me about 20,000 hours, notcounting calling on higher powers to stricken it down!)
We're going to need 2 'Y' connectors for the flaps since we
have 3 servos to connect. I just double checked the outer
wing servos: also need a reverser for those. Might as buy
2 or 3: we may need them with coordinating 2 rudders &
nose wheel and the horizontal stab has 2 servos.
Also, noticed that it is going to be difficult to adjust the
connecting rod from the servo to the flap on the outer
wings. The servo is mounted on the cover and I don't think
that plastic ball joint is adjustable. An easy way would be
use two channels: your call. (we may need a 12 channel by
the time we're done: especially if we make the pilot wave!).
This is the top view of the center wing with
the flap servo mounted(it faces to the rear-
just as the outer wing flap servos do).
There is a rectangular hole in the top and
bottom of the wing where the covering has
to be removed. The manual doesn't
mention the hole in the bottom but the
covering has to be cut away so the bottom
of the standard servo can fit in the
mounting. The two covers removed on
each side of the center servo has two 90
degree control horns already mounted
with easy connects. One end of the 90
degree control horns will go to the center
servo and the other side will go to the
flaps.
I noticed about a 1/32 to 1/16" play between the hinge balsa blocks and the holes in the
wing. I put some slivers of balsa in them to make a tighter fit and for better adhesion for
the CA. As we did with the flaps on the outer wing, follow the same procedure for the
center wing using tape and pins. All my hinges connecting to the flaps were already glued
in but it doesn't hurt to check yours: with 65 planes built times how many hinges? Esc:
there's bound to be one or two missed. Same goes for the ailerons: mine are already glued
in but there could be some missed by the 'gluers'. Also, check that ball socket on each
flap: a little CA on the nut won't hurt (easier now than when the planes flying!).
Here's a 'DUH' statement but just in case someone doesn't know:
The brass grommets that go through the rubber mounts on the servos, the rounded end
contacts the wood mount while the sharp end is for the screw head to contact. Reversing it
can cause the sharp end to cut into the mount when the screw is tightened (servos moving
in their mounts while plane is flying is not good).
Bottom of the center wing
with the servo sticking out.
I mounted the center wing
to the fuse to make sure
the servo doesn't hit
anything. All looks good. A
nice tight fit exists
between the fuse and wing.
I worked on hooking up the
flap servo to the flap
(makes sense!) on the
outer wing. I had to replace
the rod that comes with the
ARF: very brittle and broke
on a 90 degree bend.
Another one did the same.
I recall the P-38 had the
same problem. I had to put
a small S curve in the wire
to keep from binding and
to align the servo arm to
the flap socket. I'm holding
the cover outside the wing
so you can see the
alignment. This picture is
the up position.
This shows the relative
position of down. The rod
moves about 1/2".
Having the cover turned
upside down, you can see
the bends that I needed.
The rod is 3 15/16" long
from servo arm bend to
center of socket.
Of course there's a lot of
variables from my setup to
yours but it gives you a
ballpark area.
Flap up.
Flap down.
If that should be enough down!
I'm working on the rest of the flaps in
these pictures. I had to enlarge the hole
where the brass socket moves on the
flaps. Even if you miss doing it before
gluing them on, there's plenty of room to
enlarge the hole after installing them.
Flaps up.
Inner wing flaps:
I couldn't find any rod in
the ARF that seemed hefty
enough to connect the
servo to the two 90 degree
horns so I pulled one out
of my 'stock pile'. This
goes together surprisingly
quickly. One servo in the
middle connected to the
two 90 degree control
horns. Connect the 6" long
rods with the sockets to
the flaps, adjust and all
done.
Flaps down. That should be sufficient!!
I see why Twinman says the P-61
flies so much better than the P-38!
I couldn't wait and jumped to the last step of building. I dry fitted everything together to see
what it looks like: GREAT , WHAT ELSE!
The center wing, two booms and horizontal stab go together just like the P-38 did: perfect fit
on all parts. I left 1/8" of covering where the horizontal stab is jointed to the booms and just
pushed the stab into the recess. I figured this would keep any covering from coming off in the
future. Put the horizontal stab between the booms before connecting the second boom: Once
the two booms are attached to the center wing, there's no slop in there to be widening the tail
of the booms for the stab.
Booms and center wing and fuse are all connected with nylon screws. The horizontal stab is
connected with metal screws. The stab is symmetrical with duplicate patterns on both sides
and can be put on either side up.
What a GREAT LOOKING PLANE.
Page 3
This shows the center wing flap servo connection
viewed from the top.
The center
wing
bottom
view
showing
the
positions
of the 90
degree
arms with
the flaps
up.
The center
wing
bottom
view
showing
the
positions
of the 90
degree
arms with
the flaps
down.
The long dowels in the center wing
for holding the booms on. Just
keep pushing them in until they
stop. This will give you about an
inch sticking out. Slop lots of
epoxy in the hole and on the dowel
and stick it in. The dowels fit
perfectly into the center wing, but I
had to enlarge the holes a skoch in
the booms for the dowels to slide
in.
There was slop in the center wing holes
where the short dowels are epoxied. To
insure alignment after the the epoxy and
dowels were put in, I slide outer wings on
about 1/2" from the center wing. (a 1/2"
away to insure that no extra epoxy made
my 3 piece wing a one piece wing!) This
kept the dowels perfectly aligned until the
epoxy dried.
The 12 oz tank that came with the ARF is
the top one. I replaced it with a Sullivan
Flex-tank, slant style 16 oz tank (FSS-16
No.743).
The length of the tank fits perfectly in the
space but it is about 1/2" wider than the
area cut out for the original tank. I used a
razor saw to enlarge it. I cut 1/4" off each
side of the former. (that black hole in the
middle is a hole in the fire wall that I talk
about later).
The enlargement that I made is in front of
that.
This is the front view through the opening
in the firewall to see where I put the saw in
to cut off some horizontal wood to make
the bottom flat where the tank will rest.
I've never seen an open area this large in
the firewall before. It could be for air
circulation. Not sure if we're going to get a
lot of fuel in here. May have to seal this off
when we get to mounting the engine.
Tank dry mounted
and servos
mounted in the
right boom (viewed
from the pilot's
position).
From top, down:
rudder, throttle and
elevator servos. I
moved my throttle
servo to the left of
center since my
engines are being
mounted inverted.
The black guide
tubes are extra
long and have to
be cut shorter to
connect the rods
to the servos.
The left boom is
the mirror image
for servos:
From top, down:
elevator, throttle
and rudder servos.
While I'm watching a bowl game, I thought
I'd check the retracts. Neither the nose nor
the mains fit the mountings. The
mountings are the correct spacing but the
formers that hold them are going to have
to be cut.
I Used the razor saw to cut a larger hole
(slot) in the former. Then I found that the
rod that protrudes out the side of the
retract is in the way so I had to put slots in
the side of the mounts. I used a dremel
tool to remove about an 1/8" deep and 1/4
by 1/4" wide and long. This is the left
boom.
All's well in the universe again!
The nose gear retract mounting area had to
also be trimmed.
Here's about a 3/4" by 1.5" piece of former
removed.
Order of assembly for the
Spring Air nose gear (No
instructions came with it
so this is my guess!).
One of the retract
assemblies says 'nose
gear' on the top side,
although I can't find any
difference between any of
them!
(These names are made up
by me: don't know what SA
calls them)
Strut, strut insert, steering
linkage, brass sleeve,
steering linkage shaft,
retract.
The brass sleeve is a skoch larger that the steering linkage shaft so the retract will tighten
around the brass sleeve, leaving the steering linkage shaft to rotate. Tighten the steering
linkage to the steering linkage shaft. Put the strut insert into the strut, tap two set screws
and tighten this to the steering linkage shaft. Twinman says that Mike (VQ) says big 'no' on
putting the steering servo upfront. Makes sense after thinking about it (won't retract that
way)!
Other boom had 1 mount glued out of
alignment and I had to make indents not
only for the rotating shaft (center) but also
the two end screws that hold the assembly
together.
No big deal: just used the dremel to grind
it down.
The initial holes are drilled. First I used a
center punch to dimple the wood so the
drill doesn't wonder. Second, I used a
small diameter drill bit to get the initial
hole drilled.
I then drill the final hole with the proper
size drill bit. This increasing bit sizes
dramatically increases accuracy. (also
only way to properly drill through metal).
All retracts screwed in. Presently, only put
two screws in for now. Later, when I get
the struts on and check for alignment, I'll
then drill the other two screw holes. (if I
did this in the right order, I wouldn't have
to do this!). (my 'radical side' doing what
moves me at the time instead of the proper
order).
Speaking previously of possible hinges
not being glued, here's a mount in the
nose that was only dry fitted. A little epoxy
fixed that up.
I put a medium Robart air
tank in. The hole in the
former is an exact fit for
the tank but there's not
enough room to slide it in.
I used my razor saw to cut
a piece out to slide it in
and I can glue the cut
piece back in later.
The tank on the right came with the Spring Air's
400 set. As you can see, the volume difference is
significant, and important when moving retracts
this size!
I've learned in wood working, never measure when the you
can transfer measurements directly. Trying to measure
say 13/32" (hmmm, just a hair over that)....forget it! In this
case, I use these.
Can't get any more accurate than that! (which is
important for mounting engines).
Again, I center punch it to initially guide the bit.
While it's not necessary, it makes accuracy much
easier by using a mini-drill press.
As with the gear mounts, I drill a pilot hole first.
Then over to the regular drill press (also not
necessary but easier) to drill the final hole.
Some may find this a little anal but I tap and use a
locking nut (plastic insert) to hold the engine to
the mount. The tap will have the bolt, thread and
bit size on its shaft ( in this case: 8-32, #29).
There's a lot of vibration up there on the business
end and it's no fun having it come loose: not to
mention safety (but I will!).
Front view. Temporary mounting of engine to the
firewall. The firewall has 'centering' lines on it. The
engine shaft should align on the center of their
intersection. The top mount corner had to be
trimmed so it wouldn't interfere with the fuel
adjusting screw. Part of the opposite mount will
have to be trimmed for the muffler. The muffler will
have to also be ground down on the corners near
the mount in addition to the area close to the
throttle so the connecting rod can move freely. I
will also have to drill/tap a screw with a hole drilled
through the screw for pressure to the tank. This J-
tec muffler does not come with this (not sure
why!).
Side view.
Top view.
With cowl on. The engine cylinder head
just clears the inside of the cowl. I will
probably have to cut a hole for the glow
plug. Later, I will install a remote set of
wires a foot back (or so) to route 1.5 volts
to the glow plug.
Page 4
We need access holes to run the
wires from the booms to the center
fuse where the receiver will be. I
cut a 1/2X3/4" access hole in the
center wing. This needs to align
with one of the holes that are in
the ribs. The hole is 1/2" to the
right of center and 3 1/2" back
from the leading edge. Note:We're
cutting all holes on the bottom of
the wings. This picture shows the
hole for the fuse. We can always
enlarge it later if need be.
(From woodworking, I've found it
easier to take a little more off than
try to add it back on!)
This is the boom hole. Left boom (again in
relation to the pilot). This one is also 3 1/2"
back. It is a little bit off center between the
two mounting dowels. There is a rib right
between the two dowels so I shifted the
hole about an 1/8" over. Don't make these
holes too wide because the booms have
very wide triangular supports running on
both sides of the boom (obviously to give
the booms strength).
Making a hole over these will be useless
since no wires will be able to be there.
Here's a side picture showing the hole in
relation to the ribs. That hole in the rib is
where we'll use the 'ol wire with a hook on
the end' routine to pull the wires through
the center and then up through the boom
holes.
Right boom hole. In this picture, you can see the
rib that we want the hole to be next to it and not
over it.
When pulling the wires for the boom, it may be
difficult to get the wires off the hook and through
this hole so we may have to enlarge it later.
Flap wiring is shown here.
I needed the servo
reverser AFTER
the first Y
connector. The
order for the wires
starting at the
receiver is: A Y is
first. The left leg of
the Y goes to the
left wing flap. The
right leg of the Y
goes to the servo
reverser. The
reverser side then
gets another Y and
these two leads go
to the center wing
and the right wing
flap (clear as
mud!).
Flaps up (wings still on their backs).
Flaps down. (must be hooked up right, it works:
amazing!). I initially put the reverser as the first Y
but that didn't work. A little trial and error always
works well with low voltage electricity versus
trying to use this method on a new house outlet!
Note that those center flaps are at about 95
degrees (might have to reduce that angle!).
Enough to make a grown man cry! (need wireless like they have for pc's and the keyboard
and mouse: Twinman: you want to get researching on that, please!). Besides the servo
reverser for the flaps, we also need one for the elevator. I was thinking we might need one
for the rudders but visually going through the servo motions, it looks like just a regular Y
will do (we'll find out later when we actually hook up the rudders!). The engine throttle
servos also just use a regular Y harness. We'll still need to route the retract/brake lines
through the center wing. Since the nose gear, retract and brake servos are all in the fuse,
we can test all that stuff later. Everything has been tested OUTSIDE to remove any bugs
before we start routing that mess through the wings. As usual, we'll electrical tape all
connections, pull them through the holes (hopefully) and then label each one as we get it
through. How many and what length? Don't ask: too many variables. Just get lots of each
length (like servos, never have too many servo extensions ....and Y harnesses....and servo
reversers!).
Now we'll start on the spoiler/ailerons.
Using the piano wire with a hook, we pull
the spoiler/aileron wire through the hole in
the center wing and out the side of the
wing.
After normal installation of the low profile
servo (again, make sure you don't drill
through the servo mount and out the top
of the wing), the special connecting rod for
the spoilers has to be made. Since we
can't have the spoiler going up when the
aileron is going down, we need some way
of disabling the spoiler for this to work
properly. Fortunately, VQ has figured that
out by using a spring. On the PUSH
movement of the servo, the servo arm hits
the collar and pushes up the spoiler. On
the PULL movement of the servo, the
servo arm needs to move but not bind, as
it would if it was connected directly to the
spoiler rod.
The spring allows the arm to move freely
on the PULL motion. Cool!
As you can see in the picture, I had to put a bend in the connecting rod to get it to work.
The bend was so the rod can go under the sheeting of the wing. The manual shows the rod
just to the edge of the access hole. I found this caused the spring to be too compressed
and not functional. I had to cut a new longer rod. The rod is 3.5" long from the ball joint
end to the other end of the rod. The first collar (for the PUSH movement) is 1 7/8" from the
center of the socket hole. This is then slipped through the E/Z connect hole on the servo
arm. The spring is then put on and then another locking collar on the end (whew!!).
The E/Z connect doesn't use a set screw since the rod has to move freely. You have to take
the control horn off the servo before putting all this @$#% together on the E/Z connect.
Then slide everything into the hole, screw on the control arm to the servo and put the
socket onto the socket ball. I'm finding these black plastic sockets to be very loose so I'm
going to have to replace them. Hopefully, someone makes sockets the same size as the
socket ball so the brass socket ball also doesn't have to be replaced. The socket ball is
brass so it's good quality. Again, put a little AC on the nut holding the brass socket on to
prevent it from coming loose in flight.
You can now connect the rod that goesbetween the servo and 90 degree controlhorn. All the E/Z connects are alreadyattached to the 90 degree control horns. Iwanted to replace all of them with othertypes of connections but I'm finding thatthe screws holding the 90 degree controlhorns to the mounts don't come out.I'm guessing that the screws and nutswere all attached BEFORE gluing themounts in.Removing the horns would be difficult todo and it, unfortunately, means we have touse the E/Z connects. Just make sure youfile a flat spot and locktite it.
The aileron control
horn is now
connected in the
usual way
with the control
horn holes for the
clevis to be aligned
up directly over the
edge of the aileron.
The clevis's appear
to be good quality.
All we need is to
put a piece of large
fuel hose over it to
make sure it stays
closed.
NOTE: over time,
some pilots have
found ARF control
horns to age and
crack.
Your call on
replacing them. As
with all flying: all
surfaces and
materials should
be checked
BEFORE flying:
not only for the
planes safe return
to terra firma, but
also for our safety.
Routing the wires in the center wing.
Here's some the filters/chokes that can be
used to filter out that chattering that you
can get on your servos. The top one is an
in-line filter. Then there's JR's barrel and
ring filters Hitec's servo has the wires
twisted. Another way to help filter out
unwanted servo chattering. I'm using a
PCM receiver which works very well on
filtering out chattering.
(there's a lot of debate on whether PCM is
good or bad: I favor them).
Here on the center wing, I
used the hook on the right
to pull the other hook out
of the hole once it appears
down in the hole (the left
hook was inserted into the
end of the wing and
pushed in so we can attach
the wire to it and pull the
wire through the wing).
One of the extension wires
twisted before pulling it
through the wing.
The final product.
Wires from the receiver are going into the center hole. Each boom hole has the rudder,
throttle and elevator extensions. Each end of wing has the flap and spoiler/aileron
extensions. I also ran the retract air lines in. Spring Air only uses one air line (a spring in
the cylinder pushes the retracts down). (hmmmm, I forgot to run the brake air line: back to
the workbench!). I also had to enlarge that center hole an inch toward the leading edge to
get all the wires in. (took all afternoon just to do this). Everything is labeled so all should
go OK when we start connecting up all the servos.
I put the wing
tubes on the center
wing. Used their
screws (20mm or
about 3/4" in
English). The
center section is
just about done
except for working
on those sockets
Back to working on the engines. After
putting lots of epoxy on the firewall (inside
and outside), I transposed the engine
mount distances to the firewall. I used a
13/64" drill bit and put the blind nuts in
from the back and tightened them into the
firewall using one of the socket head bolts.
Without the rudders attached yet, it was
easier to just set the boom vertical on its
tail on the floor and then drill the engine
mount holes.
Engine mounts mounted. I cut about 1" off the
front of the mounts so they wouldn't show when
the cowl is put on.
Both engines and
mounts are done. I
had to trim one
engine mount for
the fuel adjustment
valve and the
muffler.
Oblique view with the cowl
on.
Page 5
First, I had to fill in the hole in the
firewall with some balsa and
epoxy.
This is a good time to make sure
none of those engine mount bolts
are sticking out the back (very
hard on fuel tanks: I learned the
hard way!).
I had one sticking out on each
boom since I had to narrow the
mount a skoch to allow for muffler
room.
I drilled and tapped holes for the pressure
to the fuel tanks. A couple 6X32 aluminum
bolts does the trick. I find ACE and other
small hardware stores has an excellent
selection of small screws that HD and
Lowes doesn't have.
I had to drill a 1/16" hole through the
aluminum screw. I cut the heads off first. I
then use two nuts and tighten them
against each other to keep the bolt from
spinning (also to hold the bolt in the vice).
Center punching the screw and using a
good quality bit are essential, plus exact
perpendicular to the drill table (there's not
a whole lot of slop allowed when drilling a
1/16" hole through a bolt that's only about
an 1/8" diameter. The aluminum bolts are
cheap though so no big deal if you break
through the side. I drill half way through
from both sides to reduce this risk and I
use cutting oil to keep friction down
(especially essential when drilling steel to
prolong the life of those bits). Even if you
break through a small amount, a little JB
weld will fix her up (just make sure you
don't block the vent hole up!).
Bolt with hole (minus nuts) put in the
muffler with JB weld. One nice thing about
having to put your own pressure tube in
the muffler is you can put it that is
convenient for how the engine is mounted
on the fire wall. In this case, it points up
and away from all the 'clutter' on the other
side of the engine mounts.
I'm partial to the '3 line' method. Fuel,
pressure, fill/drain.
The vent/pressure is the top line. The
fill/drain is the front clunk (got to use the
ARF tank clunk). The engine line with
clunk in the usual place in the back.
The trusty H2O test. Plug up 2 holes, put
the tank in water and blow and hope no
bubbles appear. Of course, it's easier to do
it now than when the engine goes out in
flight!
Tank mounted with the
usual foam. No need to
secure it since I found that
the center wing will put
pressure on the top of the
tank and the back former
will keep it from sliding
back. This was the easiest
tank mounting that I've
ever did. Usually it's a pain
to get those line through
that small hole and then
secure the tank. This was
quick and easy. The fuel
and pressure lines are 6"
and the fill/drain line is 9".
NOTE: I'm using different fuel tanks that came with the ARF.
I'm using slant front tanks. The original tanks won't give you this problem. I finished up on
the tanks but I didn't have a good feeling on the second tank. It felt a little tight near the fire
wall. After pulling it back out, one of the lines got pushed against the brass tubing and was
cut. With the 3 tube method, I had 2 of the tubes on top at about 10 and 2 o'clock and the
third at 6 o'clock. The bottom tube at 6 o'clock came through at a good angle through the
hole in the center of the fire wall. The other two tubes were too high so I took the tank out
and bent the 10 & 2 o'clock tubes down about 45 degrees. This was just right and when the
tank was put back in, the 3 tubes aligned with the center hole in the fire wall. There's
enough room to see the tubes coming out and I made sure they weren't twisted with each
other and then connected them up to the muffler and engine and let the fill/drain tubing
hang down. I took the other tank out and did the same thing to it.
I used a foot long bit to drill through the
fire wall and next former for the throttle
servo control rod.
We're raising the center throttle servo it so
it clears the outside servo. I took one of
the blocks for the fixed gears and cut it
into 4 pieces, sliced it down the middle
and then I cut each part in half and sanded
them. With such small parts, I stayed away
from the big power tools and used my
scroll saw.
Left: initial piece of wood- Right: final
product.
A little epoxy and the throttle servo will
now be 3/8" higher.
There's now enough room to connect the
throttle rod up to the servo with the short
side of the servo control arm facing to the
rear of the plane. I used the white plastic
tubing and the thin black control rods with
a 'Z' bend that were in the ARF box.
Several bends were needed to get around
the boxy muffler. A side benefit with this
thin rod and the many bends was the
throw of the servo arm and engine throttle
didn't have to be exact. On full throttle, I
get a slight bend of the wire but since the
wire connects to the engine throttle at
almost a 90 degree angle to the rest of the
rod, it acts like a buffer.
Final check routing
through the wires
that we'll use in the
center wing. After
the plane is put
together, it may be
very difficult to
adjust only one
engine throttle so
you may want to
use two channels.
I'm banking on the
thin throttle wire
and that 90 degree
turn allowing me to
make some small
adjustments by
bending the wire. I
normally use a
plastic clevis and
adjust it at the
engine throttle end
but that muffler
just doesn't allow
for such luxuries.
When I tried to put the struts in the spring
air retracts, the struts are a little too big in
diameter, even when the set screw on the
retract is completely removed. I ended up
putting some masking tape 7/8" from the
end to protect the gray paint while I hand
sanded the exposed paint and some of the
metal off.
I'm sure we'll have to do this again since
it's unlikely that the length of the strut is
exactly what is needed. (good time to get
some quality bonding time with the other
half by having her sand one strut while
you do the other one!)
GPS: general purpose stuff.
On the left is the foam cord I get at
home depot that I'll use to put
inside the tires to keep them from
going flat. Center is homemade
sanding sticks: white glue different
grades to a paint stick.
Right: 'magnetizer' from Rockler
woodworking store: nice to
magnetize all those screw drivers
to hold those small screw while
putting them in tight places.
The 3 hinges were already glued into the
rudders on my ARF. All I had to do was cut
three slots in the vertical fin. The slots are
already under the covering so not too much to
do here. I made a flat side on one end of a
popsicle stick and pushed the epoxy into the
slots. Put a little oil on the center of the hinge
pins and pushed the rudder's hinges into the
slots. Nothing unusual on the control horns
either.
The lower control rods are for the rudders.
The outer servos in the booms are for the
rudders. The clevises appear to be good
quality so I just slipped on a piece of fuel
tubing first and then slid the rod from the rear
into the black pre-glued plastic tubes.
(the top servo in the picture
is for the rudder). The black
plastic guide tube had to be
cut back to the next former
to allow movement of the
control arm. For the rudder
servo, I used Dubro's super
strength servo arms. After
aligning the rudder to
neutral and also first making
sure the servo arm is at
neutral by turning on the
receiver and transmitter, I
used a felt tip to mark the
rod where it goes over the
servo control arm. I then put
the usual 90 degree bend at
the felt tip mark and cut off
the excess about 3/8" down.
I put the 90 degree bend at
3/4" out from the servo shaft
and used an E/Z link to hold
it on.
As you can see, I'm getting
max rudder movement.
Needed if one engine goes
out. (later, we'll paint all
those white parts black so
they don't 'stick out' so
much).
Normal stuff here. Control horn on the
horizontal stab. Both sides of the stab are
identical covering and airfoil so pick the
best side. I put the control horn at a slight
angle toward the boom to make a smooth
transition to the push rod.
Next, I connected the
horizontal stab to both
booms.
The screws are 1" long. Each ends of the horizontal stab have pre-installed blind nuts. Test
out the screws before connecting the booms. One end of the stab on my ARF had the blind
nuts at a slight angle (not 90 degrees to the rib) so the screws had to go in at an angle. You
don't want to force the screw in and cause the blind nut to come free: I've done that before
and the only cure is to cut the head of the screw off so it can be fixed. I cut the covering
inside of the rudder, where the stab is attached, about an 1/8" in. This allowed the stab to
push that covering under it so it makes a nice clean appearance and also unlikely to tear in
flight. The recesses on the outside of the rudder where the screws heads go are easily
seen with the slight indentation of the covering. An x-acto knife was used to put an 'X' cut
at this spot. Both control horns mounted. I use a manual modelers drill: going through
balsa doesn't need anything more than 'hand' power.
The top servo in the
picture is for the elevator. I
taped the horizontal
elevator to the rudder in a
neutral position, hooked
up the clevis's to the
control horns and, like the
rudder, used a felt tip to
mark the push rod directly
over the hole in the servo
control arm. Bend it 90
degrees, put it all together
with a E/Z link and she's
'good to go'.
Testing the elevator:
Elevator in neutral
position.
Elevator in down position.
I cut a small notch in the
former just behind the
center throttle servo using
a razor saw. The 3 servo
wires and 2 airlines (3
needed if you're not using
Spring air retracts and also
installing brakes) come out
of the center wing directly
over the servos. I was
concerned about these
wires eventually/possibly
getting entangled with the
servo arms. To prevent
this, the wires and airlines
go through that notch and
connect with the 3 servos
on the 'retract' side where
there is lots of room. I
used plastic ties to hold
the servo wires together
and routed them through
the same former where
there already exists a large
hole.
Pretty straight forward on this. I used
electric tape to tape the servo wire
connectors to the wires coming out of
the center wing, inserted the center
wing dowels into the booms, aligned
the wires and airlines in the slot we
made, and put the 4 nylon screws in.
Putting the booms on her nose made it
easier to access the retract area to
make sure all the wires and airlines are
in that notch and nothing is being
pinched. For now, the retract and brake
lines are just looped out of the center
hole of the center wing. We'll cut them
later for connecting to the air valves.
Leave several inches of air line sticking
out of each boom so we can easily
connect them up later. That 'rats nest'
connecting to the receiver isn't too bad,
considering how much 'stuff' we're
operating!
Checked out all the
servos and all's
working good.
Drop tanks.
Figure I might as well paint them
up so they are thoroughly dry by
the time we use them. Use 240 grit
or finer to rough up the surface of
the plastic to give the surface
some 'tooth' for the paint to stick
to. First coat is primer. Any of the
spray paints at HD or Lowe's in a
can will do, but we'll need to use a
fuel proof clear coat for the last
coat. Primer is important: it's
virtually impossible to get a
smooth coat of paint without
primer.
Second coat: Black.
As with the primer, it's best to put
on several light coats than try to
cover it in one coat (also, less
likely for the paint to attack the
plastic).
Page 6
Retract system
Cut a new servo tray to lay over
the old one in the main fuse. In
the middle will be the standard
nose steering servo. Flanking the
nose servo will be two micro
servos (Hitec HS-81) to control
the retracts and brakes. I'm using
the micro servos so I can get 3
servos in the same place as the
normal two servos. Top left is the
Spring air control valve. Below
left is the Ultraprecision brake
valve.
Gluing in the air
tank and the new
servo tray. I moved
the tank back as
far as it would go
to make room for
the new servo tray.
Something to do while watching
the game:
There weren't enough decals cut
on the sheet to do the whole
canopy, but there's enough decal
left on the sheet that you can just
cut some more strips and use
those.
I'm putting all my
air and charging
outlet in the nose
of the fuse. Along
the inside is black
plastic used for
auto wire
protection. It has a
slit on one side to
put all the
wires/lines in.
The fill valve and robart's pressure gauge.
I had to
cut 1/2"
off the top
of the
strut so
the wheel
would fit
inside.
Retracts up. Retracts down.
Setting up the nose strut is presenting
some problems.
As you can see in the picture, the masking tape (the edge away from the wheel) is where I
have to cut the strut so the plane sits level to the ground. the black line above it is where
the internal cylinder is to put pressure for the oleo action of the spring. As you can see, we
have to cut below that black line. Presently, I'm figuring I can push that internal cylinder
down about 1" so we can connect the strut to the retract. I'm also going to have to cut the
spring shorter so it still works on the oleo.
I'm setting up two nose struts using the
7/16" that came with the P-61 ARF (top one
in picture) and a 3/8" strut that I had as a
spare (bottom one in the picture).
There's only a 1/16" difference in the diameter but as you can see in the picture, the overall
size and appearance of the 7/16" strut is much beefier that his smaller sister. The nice
thing about the 3/8" is no cutting is required. Comparing real pictures, the 3/8" strut and
wheel appears more scale with the 2 3/4" wheel. It may not hold up as well though if you
start going off the runway and into grass. The bulk of the weight is definitely on the mains
but being out front, severe turns at a high speed or heavy grass as high speed may do it
in.
Working on the 3/8" strut first:
I using my vise, versus using a hammer, to
push the 'plug' into the oleo. (the 'plug' being
the sleeve with a hole in it that makes a
perfect fit to the male end of the retract). I've
taken the oleo apart so not to damage the
offset weld (it can't take this kind of
pressure). I also put a piece of wood at the
other end so the end is not damaged by the
vise. I rounded (beveled) the end of the 'plug'
so it is easier to align and get it to enter the
strut.
I male end of the nose retract is a skoch
larger that 1/4" in diameter so I used a
17/64" bit to drill out the plug in the strut. (I
used a small square first to make sure the
strut is perpendicular to the drill table). As
usual, I used cutting oil to keep
friction/heat to a minimum. After drilling
the hole, all that was needed next was to
put the strut back together again. (holes
and tapping will be done later to hold the
strut to the retract).
Nose gear: 7/16" diameter strut modifications.
To get the plug out that
holds the spring against
the bottom of the strut,
I had to use a center
punch to knock it out.
I was initially worried that it may be welded in there, but my fears soon faded when theplug came out very easily. We won't be using it again because the bottom of the plug thatattaches to the retract will now be compressing the spring. We have to do this due to theamount of the top of the strut that is cut off. I cut off 2 3/4" off the top of the strut with adremel cut off disk
The plug (sleeve) that comes with the 7/16" strut
is too large in diameter to go into the strut (at
least, on mine it was). I had some pieces of a
3/8" strut laying around and this is about the ID
(inside diameter) of the 7/16" strut. I used a 1"
piece of the 3/8" strut and two of its plugs
(sleeves) to put into the 1" piece of 3/8" strut.
Again, I used the vise.
Here is the 1" piece of 3/8" strut with the two
plugs in them. We now have to drill out a 17/64"
hole in the center as we did for the 3/8" strut. I
had to sand the paint and some of the metal off
the outside of the 1" piece of 3/8" strut (we
shouldn't really call it a strut since it is now just
a larger plug (sleeve). To make sure that this
new plug is not too large to go into the 7/16"
strut, keep sanding the outside until it fits 3/8"
hole in a drill gauge ( a drill gauge just has a
bunch of holes in it indicating what size hole
each one is). Once the outside diameter fits
through a 3/8" hole, I can now press fit the plug
into the top of the 7/16" strut.
NOTE: since I had to sand the 3/8" piece of strut to get it to fit, you might as well just use
the original plug (sleeve) that came with the 7/16" strut and sand that one down until it's
3/8" in diameter. I did the sanding by putting the sleeve on a drill bit so it could move freely
and then held it against the disk portion of my table belt sander. The sleeve rotates when it
meets the sanding disk but this way, it evenly sands the entire surface.
A little care must be taken when putting metal to a fast moving disk! I used a small chisel
to keep the sleeve from coming off the drill bit and pushed the sleeve lightly against the
disk platform to help slow it down a little bit while the sanding disk does its job (this was
the only way I could think of evenly sanding the surface of the sleeve: I'll do stupid things
like this around sanders where the worst I'll get is an abrasion on the skin, Never around
cutting blades!). Always wear eye protection.
Since I moved the plug lower to where it used to be to put pressure on the spring, I had to
do some additional cutting so things wouldn't bind. The lower part of the strut that holds
the wheel, I cut off 1/2" off the top male part that slides into the upper female half of the
strut. I also cut 1" of the spring off. This seems to be about right as the oleo still functions
(amazing, luck perseveres again!).
3/8" Nose strut.
Here we have the 3/8" and the 7/16" nose struts made up. If one doesn't work, I'll have theother for a backup. The 3/8" is easier to make. The 7/16" can handle more stress. It's 'yourcall' on which is better for the parameters of your field and flying experience. Both oleosfrom the bottom to the top (not counting the wheel) is 6 3/4" long. The larger wheel on the7/16" strut made it a 1/4" longer
7/16" Nose strut
For the nose strut, we need to drill and tap
for two set screws (two to make sure if one
fails, we have a backup, Freely translated:
lets not hose up our 2000 buck plane)
Here's the pilot holes drilled on the nose
strut for the set screws. (This tapping not
needed for the mains since the whole strut
goes into the retract).
After using a #40 drill bit to drill the final
holes in the strut, we tap the two holes. (A
well stocked hobby shop should have
packages of a drill and a tap as a set).
(remember:make sure you use some oil
when drilling and tapping).
After drilling and tapping, the set screws
can now be put in.
I just noticed that the main wheel sticks
out. Those black plastic pieces in the ARF
are going to be functional. Looks like we'll
later cut a hole in our gear doors and glue
the plastic covers over the hole to cover
the wheels. (hmmm: picture 38 in the
manual shows the procedure)
The nose retract and strut are installed.
The retract must meet the back of the
retract wooden mount. This is necessary
so the steering control arm has room when
the retract is up (you'll see this in the
second picture). I also had to trim the one
former holding the back of the wooden
mount. You have to cut the side off so the
control arm can move by it, and also so
the back of the retract sits all the way back
on the end of the wooden mount.
Nose strut up.
Here you can see
how far back the
retract is from the
front former. You
can also see the
room needed for
the steering arm as
the arm goes
below the top level
of the retract
wooden mount.
Note that all
3 struts
have the
oleo
scissors
toward the
front of the
plane, as
with the
prototype.
If your
retracts
bind: check
that you
have the set
screw all
the way in.
Also,
loosen (one
at a time)
each of the
four screws
that hold
the retract
to the
wooden
mount until
the retract
moves
freely. The
last screw
loosened is
causing a
bind. You'll
have to
shim that
corner up
before
tightening
the screw.
Left main up. Right main up.
Page 7
Running wires from the battery up to the
nose on/off switch and back.
I connected the
retract, nose
steering and brake
servo to the
receiver. Looks
like the nose is
backwards to the
rudder, so either
another channel or
a servo reverser
(I'm going
reverser). The
brake is a dial and
on the front right
(aux 3) of my JR
radio. I've opted to
use aux 3 over aux
2 which is on the
front left.
I'm going on the assumption that, after landing, my left hand will be busy steering the
plane so my right hand can control the brakes. When taking off, my left hand will again be
busy steering. My right hand shouldn't be busy until the plane goes several feet. Any ideas
on this...besides growing another hand? This may be just what each of us is comfortable
with, also the limitations of the transmitter.
I plan on putting the receiver where you presently see it in the picture between those two
formers in the picture. I also have the battery in the same place but down beside the air
tank. I'm putting another battery on the other side (1400ma, 6v each). I'm starting with the
batteries here and hope they won't have to be moved to get proper CG.
Retracts and
brakes with
pushrods
connected. I
hooked up the
retract and brake
valves to the micro
servos with some
1/16" thick wire
with Z-bends on
each end. The
micro servos are a
good choice for
these since we
only need 3/8" -
1/2" throw to make
them functional.
Since I had the
retracts 'hooked
up', I thought it
would be a good
time to check out
the CG. The
manual says CG is
3-3 1/2" back from
the leading edge of
the wing. The end
of the screw driver
points to where I
put a piece of
black tape. I split
the two extremes
and put the tape at
3 1/4".
Here's a
low angle
where I'm
using foam
to support
the plane
while the
retracts are
up. I put
the props
on and just
taped the
cowls to
about
where they
will be
(presently
the cowls
won't fit
over the
engines
with the
mufflers on
the
engines).
Top view.
Got most
of the
things still
not added
sitting
about
where they
are
suppose to
be. Well, I
can forget
about
putting
those
batteries in
the center
of the main
fuse. I had
to move
back a
good inch
to get CG.
The batteries are now going into the nose. I put both of them up front and the CG is now
about a 1/4" back from where it needs to be. I think some heavy spinner nuts should do it.
There's plenty of room in that fiberglass fuse so we can add lead to that later. When
mounting those engines, a little farther forward won't hurt. I remember how light the
horizontal stab was when I was assembling it to the booms.
It's amazing how something so light can offset the business end with all those motors, etc.
('give me a place to stand and a lever long enough and I will move the world', Archimedes).
I'm glad I wasn't building this from scratch, I probably would have needed to add 10 lbs to
the nose.
Here, both battery switches and charging
jacks are in the front servo hole. I thought
that I needed two 'voltwatches' but it
appears that the 'juice' goes through the
receiver from one port to another, since
when either battery is turned on, both
'voltwatches' came on. So save your self
some $$ and just buy one. The air valve
and gauge is on the right.
Foam was lined in that hole on top for two
1400ma, 6v battery packs.
With both batteries in the hole, there
wasn't room to wrap each battery pack but
the foam lining in the cavity should work
for vibration reduction.
I had to put a couple notches in the former
so the two 5 cells packs would fit.
Bottom of nose.
I'm using a common kitchen door latch (at
Home Depot or Lowes) to hold the nose
cone onto the front of the fuse (need easy
access with all the connections up there).
I'll build up a wood brace in the nose to
mount the male end of the door latch.
There's not a lot of wood to connect the
latch so I used 1/8" ply and made a 'U'
shaped piece to hold the latch to the fuse
Here's all the wires
and air lines going
along the side of
the fuse. I cut extra
holes in each
former to route the
wires through and
to hold them in
place.
I took out the black
auto tubing
because it couldn't
hold all the 'stuff'
going up front.
Once we're sure
all's good, we'll
use some plastic
ties to hold
everything
together.
Now, I'm working on that door
latch to hold the nose onto the
center fuse.
I slid the nose on 1/8" ahead of the
panel lines on the fuse nose.
(The nose isn't symmetrical, the
flat end goes on top).
With the make part of the door latch on the
female end (rollers), I measured from that
1/8" forward of the panel lines to the end
of the door latch. Mine was 5 1/8" so I now
know my mount has to be that far down in
the nose.
Bottom of picture: I used a piece of cardboard and kept
trimming it until it fit to the depth that I wanted. Top of the
picture: I then used the cardboard template to trace on
1/4" thick piece of balsa and kept sanding until it finally
laid in the recess of the nose at 5 1/8" down. Those paint
sticks with 80 grit paper glued to them made quick work of
any sanding that was needed. I put 4 holes in the balsa for
any future buckshot we might pour in for nose weight. I
marked a straight line on one end (flat side of nose) of the
balsa to keep the orientation the same in relation of the
balsa to the nose.
Side view of the 1/4" balsa mount.
I used some shoe polish and put it on the back
plate of the male end, pushed the nose on to get
the imprint and drilled and screwed her on. Works
great. (The spouses lipstick should also work well:
blame it on the kids! her fault anyway: you don't
leave your tools laying on the counter!) I epoxied a
1/16' piece of plywood on the balsa to give the
screws a little more solid surface to grab onto.
Steering.
Used two pieces of
white tubing
(supplied in ARF),
and cut them 12"
long for each side.
I kept the white
tubing 1/2" behind
the back of the
retract so the
steering arm
wouldn't hit them
and also room for
the pull/pull wires
don't bind.
I drilled holes in
two of the formers
to hold the white
tubing. The
pull/pull wires are
connected in the
usual way: looped
through the
steering arm and
back through the
brass tubing and
then back through
the brass tubing
again and then the
brass tubing was
crimped.
This shows the
retract down. The
white plastic
tubing keeps the
wires way to the
sides so the strut
and wheel don't
hang up on them.
This shows the retract up.
The white plastic tubing
goes through the large
existing hole in the first
former after the back of the
retract. As you can see,
this allows the white
tubing to flex, if needed.
Retract back down.
The white tubing has gone
back to its original
position.
Here's the details for connecting the wires
to the servo end. Same double looping and
crimping of the brass tubing.
Standing for the first time with functional gear, strut and steering. The center fuse has
been been attached with the two nylon bolts. Not bad on getting all those wires into the
fuse. The receiver went on one side of the air tank and I pushed the wires on the other side
of the tank. I pulled the receiver antenna out the back and plan on connecting it to one of
the vertical fins as in the prototype. The contact surface of the fuse to the center wing is
pretty wide so I had to use a piece of that left over white tubing to push a wire or two so
they weren't being pinched between the fuse and center wing. I checked the air brake valve
and it's working. All struts have the 'scissors' pointing forward. I used the original strut for
the nose wheel and have the smaller one set up as a backup. (gettin' there!).
Cowls
I made a cardboard
template taped to the
boom so it won't move
when we take the muffler
off and slide the cowl on.
After cutting holes in thetemplate, I folded thetemplate back, took offthe muffler and slid thecowl on and put thetemplate back down overthe cowl. I initially cut asmall hole for the mufflerand head of the engine inthe cowl, and then slidthe cowl back on to makesure we are in the'ballpark. If you look realclose, you can see thefelt tip marker lines forthe engine head on thecowl.
The holes are enlarged a
little more and the cowl is
put on again to make sure
the glow plug is in the
center of the hole.
Sliding the cowl on I had to
make a cut all the way
back for the muffler. In the
picture, one side of the
cowl lifts up to get it by the
muffler.
I put masking tape on the
booms so I could make a
mark 'X' inches back from
the pre-installed cowling
blocks. After sliding the
cowls on, I knew how far in
the mounting blocks were
under the cowls and drilled
holes at these locations. I
did one hole at a time and
put a screw in the hole to
insure the cowl didn't
move, including checking
proper distance for prop
clearance.
I used Du-bro's cat no 531 no 6 X 3/4" button head sheet metal screws to hold the cowlson. Although not exact (couldn't find any), I used Harry Higley's big hubs 5/16" X 24 NIN516hubs. After sanding with 240 grit and priming, I painted the props black with yellow tips.
Shield installation.
The front fiberglass shields (covers) go
just behind the cowls. I had to cut part of
the front off (hidden when mounted) so it
would form around the boom.
Here it is mounted.
The manual says
to epoxy it but I
like using the
button head
screws. The ones I
uSed are Du-bro
#526 (#2X1/2" ) or
#525 (#2X3/8" ).
Looking at the end
of the center wing
for guidance, I put
the screws in
where there were
stringers, etc. I
noticed that the
leading edge has
plywood
sandwiched in it
for strength. (you
can see it in the
picture).
Rear boom fiberglass shields (covers): I
drilled 10 holes in each cover. Again,
aligning the holes where stringers, etc
were showing on the end of the center
wing rib to give the screws some 'meat' to
hold onto. Later, I found I could just use a
manual hand drill to put extra holes in: The
part on the boom needed two screws to
hold it against the side of the boom.
The back shield is
mounted. There is an 'R'
and 'L' in the inside
corners of each shield.
Although they look
identical, I put the 'R' on
the right boom (from the
pilot's view). In the picture,
you can see the 'R'. (the
front shields are
symmetrical).
Page 8
Gear Door Hinges
I tested the ARF hinges on a piece of balsa and couldn't find a suitable solution to using
them. Instead, I got some sonictronic hinges out that I had left over for the P-28. These
seem much better.
The key on the hinges is having the hinge pin along the top surface of the door and fuse.
The door will rotate along the axis of the pin.
If the pin is below the surface, the door will bind.
The ARF hinges have a base that is on both sides of the pin whereas the Sonictronic hinge
base only goes to one side of the pin. This allows us to get the pin very close to the
surface of door and fuse.
I used Sonictronic's #132, tri-cycle door kit. The Sonictronic set has a sprung hinge which
is used on each door. This forces open the door. I believe there is only 1 set of sprung
hinges in each set so you'll have to buy 3 sets. The rest of the hinges set can be used on
tail draggers. I had to cut notches in the fuse so the hinge pin can be at the surface of the
fuse. That notch is 1/8" deep or a skoch less and also a skoch wider than the hinges. You
also want a flat surface below that notch for the base that will be epoxied to it. As with the
ARF hinges, I drilled 4 holes in each base so the epoxy can ooze out and form rivets.
The front hinge is sprung
and the back one isn't.
Inside view.
The door is epoxied to the
fuse.
Both doors in.
The spring forces both
doors open. One control
horn has been epoxied in.
The elastic string (wal-
mart's sewing section) will
be tied between the two
control horns and the strut
will pull it down along with
the doors (in theory!).
Doors open with
elastic band
across the two
control horns.
Doors closed.
(Miracles never cease, it works!!) I still have to epoxy in the black plastic covers onto the
gear doors.The wheel goes below the surface of the gear doors on the nose wheel so no
cutting is needed on the gear doors.
Door hinges (mains)
First picture:
We're not so lucky with the mains: the doors have to be cut for the wheel. The brakes
offset the wheel so it is not exactly in the middle between the doors so I had to cut each
door differently. If you're not using brakes, your cuts should be symmetrical on both
doors.
Here's the inside
view of the black
plastic cover. It
has to be trimmed
so it doesn't hit the
wheel.
All cover doors and
gear doors 'dry fitted'.
Gear doors for the
boom. The sprung
hinge is on the
right.
Gear doors for the boom. Outside view.
No cutting here: just epoxy them on (with holes in the hinges for better holding power).
Installation on the
boom.
Used control horns with the elastic to close the doors. I had to epoxy 2 more control horns
on with the new ones higher up on the doors (where the doors meet) so they would close
completely. Since the strut is to one side, the strut puts unequal pressure (at a different
angle) on each door. Too compensate, I had to put move the control horns up. Since the
control horns are are now on the far side of the doors, you could probably cut them so
they are stubby (with just one hole) so they wouldn't be so noticeable.
Gear doors cut
away for the wheel.
With plastic covers
glued on.
Doors open with
plastic covers on. I
also had to cut the
plastic covers so
they wouldn't hit
the wheel. Usual
procedure for the
plastic covers:
sand the edges
and then epoxy
them on. Paint the
insides before
installing them:
unfortunately I
didn't think of that
before installing
mine so I'll have to
brush the paint on
instead of spraying
it on.
You need to cut the bottom of the nose
cover so the gear doors can close.
Each wing gets 2 screws
on each side. A drill bit
was used to drill a smaller
hole in the metal wing tube
via the already existing
holes in the bottom of the
wing.
I used Dubro's #383,
#4X3/4" socket head sheet
metal screws to hold the
outer wings on. I like the
socket heads over the
phillips since they are less
likely to slip/strip the
heads and you can put
them on real tight.
Decals
Decals were added. Not a
whole lot of work here.
After putting the numbers
on the tail, I cut some
small squares from the
cockpit decals and put
them on the screw holes
that hold the horizontal
stab on.
Don't do what I did and put
those red rectangles in the
wrong place. After
checking my reference
book, they should be
between the red lines on
the wing between those
two white circles (where
the red 'dots' go).
I took liberty on the nose
art. Since my on/off, air fill,
etc are under the nose
(and removable), I had to
put the female behind the
nose cone and the 'lady in
the dark' completely on the
nose cone. Putting part of
each on the cone would
result in them never being
aligned.
P-61 Flys!
P-61 in her maiden form: ie, no cowls and retracts stay down.
What the pics don't show is the first REAL maiden flight. I took off and she immediately
banked left: able to control her but barely: needed 10 clicks right aileron to fix. Then only
half a lap, the right wheel and axle was hanging there by the brake line. The dam pit crew
didn't tighten the set screw!! I had three other pilots around me which helped a bunch.
With the doors and the unlikely possibility of the retracts going all the way up, it was first
decided to land on the asphalt runway.
Another good point made was once the right struts touched the runway, she would have a
tendency to go to the right. That was good so I was ready for it. I used about 40% flaps and
she landed nicely. I was surprised at how little metal that was removed on the bottom of
the one retract: I would guess about 1/64". The set screw was still in there and not even
damaged so that shows how little metal was scraped off. I flattened the axle (which I forgot
to do while assembling her) and took her up again.
Flew great and she landed very lightly on all three retracts at once: looked cool. She lands
pretty easy and slower than the B-25. Watch those takeoffs; get plenty of flying speed
before taking off and make that climb nice and gentle. Both with the B-25 and P-61, I
started the throttle slowly and then gained flying speed.
ps: I'm the ugly one on the right!
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