Vq Model P-61 Black Widow Arf 90 Rc

Piccole Ali Aeromodellismo dinamico online

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)

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2009 Piccole Ali – Stra’ (Venezia) - Italia

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Il P-61 “Black Widow” fu il primo aereo Nord Americano ad essere progettato fin dall’inizio per il ruolo di caccia notturno. Quando arrivo negli squadroni di combattimento, verso metà del 1944, gli obiettivi erano piuttosto scarsi. Northrop dovette impegnarsi notevolmente con il P-61 “Black Widow”, di molto il più importante contratto mai ottenuto. Soddisfare le prescrizioni del committente per un velivolo con tre membri di equipaggio fu una delle tante sfide affrontate dal team di progettisti. Per l’intero 1941 – a dire il vero, per tutto il conflitto- emersero continue variazioni ingegneristiche che ritardarono lo sviluppo del P-61. Le armi furono ricollocate, serbatoi aggiunti, superfici di controllo riprogettate. Le consegne iniziarono nel Maggio del 1944 quando il 348^ Squadrone Caccia Notturno (NFS) ricevette i loro “Black Widows”. Il P-61 aveva una manovrabilità eccezionale, considerate le dimensioni, grazie agli ampi 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 mm Lunghezza fusoliera 1710 mm Superficie alare Peso 8380 – 9280 g Motore 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 2009 Piccole Ali – Stra’ (Venezia) - Italia

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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

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Aeromodello radiocomandato / Radio Control Model

2009 Piccole Ali – Stra’ (Venezia) - Italia

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.

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.

Page 2

This is the box of 28 or so servos ready for my P61 (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 is high 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, not counting 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 rearjust 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 Jtec 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 goes between the servo and 90 degree control horn. All the E/Z connects are already attached to the 90 degree control horns. I wanted to replace all of them with other types of connections but I'm finding that the screws holding the 90 degree control horns to the mounts don't come out. I'm guessing that the screws and nuts were all attached BEFORE gluing the mounts in. Removing the horns would be difficult to do and it, unfortunately, means we have to use the E/Z connects. Just make sure you file 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 the plug came out very easily. We won't be using it again because the bottom of the plug that attaches to the retract will now be compressing the spring. We have to do this due to the amount of the top of the strut that is cut off. I cut off 2 3/4" off the top of the strut with a dremel 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 the other for a backup. The 3/8" is easier to make. The 7/16" can handle more stress. It's 'your call' on which is better for the parameters of your field and flying experience. Both oleos from the bottom to the top (not counting the wheel) is 6 3/4" long. The larger wheel on the 7/16" 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 the template, I folded the template back, took off the muffler and slid the cowl on and put the template back down over the cowl. I initially cut a small hole for the muffler and head of the engine in the cowl, and then slid the cowl back on to make sure we are in the 'ballpark. If you look real close, you can see the felt tip marker lines for the engine head on the cowl.

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 cowls on. Although not exact (couldn't find any), I used Harry Higley's big hubs 5/16" X 24 NIN516 hubs. 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 (walmart'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!