INTRO
 
September 2010, I was looking for a new Multi-engined Bomber as a successor to my 4-engined  Bomber B-17 Flying Fortress (1:8, Span 4,00m.= 158").
She is still flying, but is an old lady now (1994- 2015; 21 years and over 800 flights), and my P-61 Black Widow is a Nightfighter, not a Bomber!
In any case, again it had to be from World War 2 and at last I chose;

The Douglas A-26B Invader,  scale 1/5,9th (1:5,9, span 3,60m.= 142")

PROTOTYPE & DOCUMENTATION.
With the Design of the A-26 Invader was started in April 1941 by Douglas, this as a replacement for their A-20 Havoc.
The original USAAF specifications called for a multi purpose attack aircraft that would be faster than the Martin B-26 Maurader, would carry a greater bomb capacity than the North American B-25 Mitchell and be more manoeuvrable than the A-20 Havoc.
The result was the A-26 invader, a more powerfull, faster, and more devastating war-machine than its predecessors, it was destined to replace.
The A-26 was proposed to the USAAF in three variants:
- A-26A. A Night-Fighter version, which was cancelled as it did not prove superior to the P-61 Black Widow.
- A-26B. A Gun Nose version that could be used for straffing and bombing.
- A-26C. A Bomber version with a glass nose.
The Invader made it's first flight on July 10. 1942, after some intensive testing, the aircraft began arriving in Europe by late summer 1944. Soon afterwards, reports from the front began mentioning the lack of visibility, firepower from the six gun version, and problems with the oil temperature. Modifications were quickly incorporated in the form of a new clam shell canopy, instead of the flat top canopy, an eight gun nose (50 caliber), and a redesigned oil cooler intakes.

The Invader participated in many wars and campaigns including WWII, Korea and Vietnam.
Two types of engines could be installed on the Invader. The powerplants consisted of either two 2000 HP Pratt & Whitney R2800-27's
or two Ford built R2800-79's. Both these engines were similar in performance, except for the fact that the Ford build powerplants were equiped with water injection to boost the war emergency rating to 2370 HP at sea level.

The imitated prototype; (see pictures 000A till 000D)
As prototype I chose an A-26B of the Flying Weather Center, Project Thunderstorm (a number of P-61C Black Widows were also used for this Project!).
So a number of Invaders were assigned various tests duties in the postwar years. The chosen A-26B, the AC-356 (434356),  so was used to test the effects of storms at the All Weather Flying Center located at Clinton Country Airport in Wilmington Ohio, during 1947.
The Plane had a bad accident  03 Oct. 1951 at Salt Lake City.

Documentation:
 I had  19 books of the A-26, some on paper, but most in PDF. (some have excellent side- views, colour drawings, photos and details). But from the chosen one, only one B&W photo and one colour picture. Some more B&W photos I have found on the Internet, and later on I got some Photos, and the official FS Colours. from the National Museum (NMUSAF/MUA Research Division).
The Aircraft was overall Natural Metal (FS 17178) with Red (International Orange FS 12197) and Yellow (Orange Yellow FS 15538) trim.

Plan, Electric Retracts & Engines (see photos 001 till 003)

Starting Oct. 2011;
-Drawing: Again the plan was drawn by myself, completely worked out, 99,90 % scale and nothing was left to a mischance. Everything, down to the last detail, was well considered and put on paper (old-fashioned isn’t it!), and the construction was kept as light as possible. Only the ribs were drawn with the computer, because the wing is tapered, and it has an airfoil changing towards the tip! (35mm slides were made from the more side-views and projected  until the right scale, traced on transparent paper and afterwards the construction was drawn in, sections were drawn and also all the formers, etc.!).
The plan was ready in Jan. 2012 after 300 hours work!

-The electric Retracts (Photo 003) are the same construction as for my B-17 and P-61 model.
The tricycle Retracts again I had build myself in the spring of 2012 , this in connection with the drawing, otherwise there would come problems during building! (electric via a screw-spindle and micro-switches, and a gear , ratio 1:30)

-Engines (Photo 135)
I am very Satisfied with all my Laser 4-stroke engines:
- 4x Laser 70 (11,5cc) in my B-17 Flying Fortress (Scale 1/8th, span 4m., weight 19,3 kg).
- 1x Laser 70 (11,5cc) in my Spitfire (Scale 1/8th, span 1,40m., weight 2,8 kg).

- 2x Laser 240-V twin (40cc) in my P-61 Black Widow (scale 1/6,6th, span 3,10m, weight 18,5 kg).
- 1x Laser 240-V twin (40cc) in my P-47 Thunderbolt (scale 1/5,9th,  span 2,10m, weight 8,5 kg).
- 1x Laser 240-V twin (40cc) in my Waco YMF (scale 1/5th, span 1,85m, weight 8,5 kg).
 
So again I chose 4-stroke Laser Engines:  2x 240-V twin (40cc). The A-26B will be larger (scale 1/5,9th, span 3,60m) and heavier ( + 22 kg) than the P-61, but the P-61 is a Fighter and the A-26B is an Attack Bomber and does not need making a looping etc.
According to my calculation, 2x Laser 240-V twin should be sufficient enough, for the ± 3,5 kg more weight in comparing with my 18,5 kg P-61 Black Widow.


THE BUILDING.

Fuselage & Tailplane (see pictures 004 till 046)
So in Dec. 2012  I started to saw the Fuselage formers.
Some formers are out of 3mm ply (200 gr/0,1m²), some of 3mm Liteply (140gr//0,1m²) and some of 3mm Balsaply  (90gr//0,1m²).
In Jan. 2013 I started to built the fuselage, because that the A-26 Bottom is mostly flat, stringers (balsa & some ones spruce) were pinned down on the building board, but for the nose and the rear bottom stringers I had to make supports of 15mm plywood. The bottom stringers, in the area of the typical rear bended bottom change over, I made of 3 layers thin balsa (laminated).
Formers, together with the strenghteners were glued (Nose gear area - Wing area - Stabilizer area), so also the the stringers.
Provisions for the fuselagehalve-joiners were build in (flat springwires in flat brass tubes + 4x M4 socket bolts, which are connecting the dual formers),  the  extra pair of rootribs for the fuselage I did not glue on them yet (later as the winghalves open construction is ready, so that I can still pinpoint everything). The Wingjoiner tubes were glued in, adjusted and pinpointed with help of the two wing-root ribs and the two fuselage ribs (the wingjoiners themselves are in one piece dural tube; front one Ø 35mm, rear one Ø 20mm).
The Stabilizer-joiner tubes and root-ribs were not yet glued, because they are dihedral, and I had to built the Stabilizer-halves first to adjust and pinpoint everything.
The framework was planked as far as practical and possible, the rear fuselage top not yet, this in connection with the stabilizer and Fin., but some provisions and installations had to be made first (Servo bearers, tubes for closed loop, and so on! Wing and tailplane fairings have to be build on later, the flowing lines for them were being achieved with some of the formers).
After the glue was dry (mainly clear PUR. construction glue), the fuselage halve was removed from the building board and turned upside down and supported on foam blocks, and the rear lower surface was planked.
Now the rear fuselage could be separated  from the front half, by loosening the 4x M4 socket bolts and saw through, between the 2 dual formers and through the flat brass tubes. In this way it will fit accurately! 
Than  front halve lower surface was planked and after this, the Nose-wheel doors and Bomb-bay doors were cut loose from the formers (will fit also accurately in this way), now it was 8 feb. 2013.
 The fuselage contains 8 servos:
-3 in the tailplane (2x elevator , 1x rudder).
-3 in the front beneath the cockpit floor (1x control-linkage to the nosegear-wheel, 2x servo-switches for electric Retracts and for   landing-lights).
-2 in the bomb compartment ( 1x retractservo for the bombdoors, 1x servo for the releasing the bombs in two steps)

 
The stabilizer & Tailplane (see photos 047 till 067)

As I wrote before, I had to built the Stabilizer first (NACA 0012), before I could glue on the Tailplane ribs and Stabilizer joinerguides to the tailplane.
First I made raised supports (photo 048) out of 12mm cheap ply to built on the stabilizer-halves. On these, with sellotape between it, the lower spars were pinned, then the ribs could be glued on (ribs with an right angle to the mainspar support!). The provisions for the Joiners for Stabilizer-Tailplane were made (carbon tubes; the front ones Ø 9mm, the rear ones Ø 11mm), so also the square Brass Tube for the Elevator Linkage and also for the 6mm ply hinges (and 1,5mm pianowire through a plastic tube). The upper spars and also the leading edge were glued on.
Now the open construction was ready, and could be taken of the supports for adjusting and pinpointing to the Tailplane.
As everything was adjusted and pinpointed I could glue the Tailplane ribs and stabilizer joinertubes, on and in the Tailplane, with the Stabilizer-halves slided on. (the stabilizer-halves were secured later with metal-screws)
Now the stabilizers could be planked. First the under-surface and than replaced on the supports and weighted down, this ensures the retention of a true straight wing. The same procedure was followed for the upper-surface, and after planking the rudders were separated from the stabilizer-halves and became a convex leading edge, this in a cavity of 0,6mm ply strips (photo 68, Rudder too).
The inner elevator closed loop linkage on each side for the removable stabilizers were built in (the two servos not at the rearend , this in connection with the extra weight at a wrong place), square brasss tube on the elevator, sliding into a twisting square brass tube with control horns and supported in Paxolin (Pertinax) bearers. The inner rudder linkage is also closed loop to a control-horn on a 90° bended 4mm pianowire , and the rudder servo is between the two elevator servos in the front of the tailplane, the fin-construction and the rudder are build on in one piece.(Photos 057-059).
Now the Fin and the rudder (NACA 0009), in one piece with it, could be constructed, hinges are 6mm ply (and 1,5mm pianowire through a plastic tube), after planking the rudder was separated from the fin and became also a convex leading edge, this in a cavity of 0,6mm ply strips too (photo 68).
1mm Ply was applied for constructing the fairings, and upperside of the tailplane could be planked now (photo 063-065).
After this 1mm ply was applied for constructing the tip blocks (photo 066-067), and now the Tailplane was ready.
The Elevators and the Rudder I have covered with Solartex, but this after I had applied these with 1mm balsa strips on the 1mm balsa sheeting, this for imitating the ribs as at the real one.

Cockpit & Gunner-compartment (see photos 069  till 077)

The whole cockpit hood is removable (as with all my large models, and the nosegear controls are very accessible).
Also the gunner hood is removable, from in here I can bolt the two fuselage parts together, the backwards bomb-room is accessible also from here, the front bomb-room is accessible when the cockpit-hood is removed. So I don't have to crawl under the fuselage for this all!
The hood has an extended floor, which fits into the fuselage, just above the retracted nose-wheel, this for a scale cockpit interior with the two crew members, the third crew member  sits in a separate cabin more rearwards (Gunner-compartment), and this cabin with an extended floor too, is also removable.

12th mai 2013;

The construction of the fuselage with tailplane and stabilizers was ready now. I stopped building now, because the flying season for 2013 had started already.
With the Wings I started in october 2013.

Wings & Nacelles, 30 Nov. 2013; (see photos 82 till 112)

After a month sawing, the parts for the Left & Right wings & nacelles were ready at 30 nov. 2013.
Formers for the Nacelles and the ribs are out of Balsa, Balsaply, Lite-ply and Birch-ply. Some ribparts are out of paxolin (pertinax)
The wings have an own mix NACA profile 2414 / 2314 on the inner-wing, and than further on, in the outer-wing, progressing to NACA 0014 profile section at the tip. So an aerodynamic wash-out has been build in (a geometric wash-out with just twisting up ribs with the same profile, and so changing the chord incidence angle slowly, always gives drag!).
Wings I always build on raised supports (strips of 12mm cheap plywood), it allows building on later the nacelle construction. The  wash-out and the dihedral are already build in these supports (matter of drawing and calculating !). Because of the large wing chord I will use 3 supports: under the main spar, rear spar, and rib-ends.
On these, with sellotape between it, the lower spars were pinned, then the ribs for the Inner-wing could be glued on, also the upper spars. The ribs 1 and 4 till 8a (because of the Nacelle) + 8b are at a right angle to the building board ! The ribs 2, 3 and 9 till 22 are at a right angle on the Supports! Before that, some Nacelle formers (N4 till N10) were slided on their place, not glued yet, only for adjusting some ribs. After the glue was hardened the Inner-wing construction was taken of the supports and the same formers were glued now to the ribs, and the construction was placed back on the supports.
Then the guide tubes for Inner-wingjoiners to the fuselage were adjusted-pinpointed (parallel and 0°) and glued. The same for the Outer-wing to the Inner-wing, for this some ribs were glued on the lower spars for the Outer-wing (Photo 90).
The Inner-wingjoiners are dural tubes ø 35mm at the front, and ø 20mm at the rear. The Outer-wingjoiners are a dural tube ø 25mm at the front, and a carbon tube ø 11mm at the rear. (later on secured with parkers straight through woodblocks in the wing and woodpieces in the tubes).
Now the other Outerwing-ribs were glued on the lower spars,  so also the upper spars and leading edge. Some provisions were made for the Fowler Flaps and Ailerons, wing-guns and landing-lights (Photo 91 till 97).
The Fowler Flaps are going max. 50mm rearwards and  max. 50° downwards (scale). Now I could start building the right-wing, also on raised supports (The same but in mirror!).
First the innerwing, but the guide- tubes for the wing-joiners were not glued yet. I slided the joiners into the fuselage, slided than the Left Innerwing on to the tubes, than the Right Inner-wing, and checked if the Incedence of both wings were the same. The Tailplane was connected to the fuselage and checked and adjusted the Right inner-wing over the stabilizers with the Left Innerwing (Photo 98), and glued the wingjoiners to the right Inner-wing ribs. The Inner- and Outer-Right-wing construction was ready at 1 feb. 2014.
At first now I made myself the landing-lights for the Outer-wings (see photo 101 & 102), and the right outer-wing could be sheeted (photo 109)

Nacelles; (see Photos 104 till 108)
Some Formers were already glued on to the wingribs, but to slide and glue on, the Nacelle Strengtheners (photo 84) into these formers, I had to saw out the space for the Nacelle in the raised wingsupports (photo 104).
Now I could glue on the absent Nacelle Formers (N1-2-3, and N11 till N14), also glued the Landinggear-bearers to these strengtheners, also the wheel-door servo was installed.  Made some provisions for; - The tankroom with hood. - The room with hood for Receiver, Engel-powerbox, 2 batteries and throttle-servo. (1x reciever in each Nacelle. But later on all this was moved to both sides in the front of the fuselage nose. Because of  the C.G.!).
Stringers were glued on (photo 105), and the Inner Rightwing with Nacelle was ready to be sheeted, the underside first and the wheelbay doors were cut out (photo 106). Than the upperside was sheeted and the retract with wheelbay-doors were fitted.

At 18 march 2014, the Right-wing (Inner-wing with Nacelle and Outer-wing) was ready, now the Left inner-wing could be provided with the Nacelle Strenghteners - the absent formers -  the Landinggear-bearers, wheel-door servo, throttle servo and stringers, etc. For sheeting I had to build up the raised supports again, but in mirror image! At first the underside of the Left Wing & Nacelle were sheeted (photo 112).
At 18 april 2014 the left wing (Inner-wing with Nacelle and Outer-wing) was ready too, now I had to provide the wing-fillets on the fuselage and  fore that I needed the both finished Innerwings, left and right, to adjust the fuselage-rib to the inner-wings, and that should be the last construction of everything!
At 5 May the Fuselage-wingfillets were ready, and the Bomb-bay doors + Nosewheel-bay doors were attached to. To release the bombs, the bombay will get trapdoors with a separate servo and servochannel.
Now I stop building.
When I started the project, the estimated weight was 22 kg (48 lbs), the engines were calculated for 23,6 kg. (52 lbs). The total weight up to now is 17,7 kg (39 lbs); 3x retracts, 2x engines, 20x servos, 6x batteries, 2x receivers 2x PMS Plus (Engel Powerboxen), 3x crew, included!
Excluded 2x turrets- 2x cockpit- 2x engine cowl- 1x nose cowl- details, and not to forget the Finish.
 

I continued in october 2014, making mouldings for the turrets, cockpit and engine cowls,  and making details etc.

Mouldings;

Nov 2014. flying Season 2014 is over, so I started to make the mouldings for the GRP parts  and clear cockpit + gunner- compartment (photos 125-132).
After that I made the GRP Parts for the both Turrets & Nosedome in Januari 2015, I made the clear cockpits (vacuum formed) in Feb. and also the Instrument panel for the Pilot. Than the all the details for the cockpit and the gunner-compartment, placed the pilot and navigator/radioman on their seats, the gunner on his seat behind his gunsight (periscope), and glued on the clear vacuum formed parts. On these clear parts I glued aluminium tape for imitating the cockpitframe.
Than I fine-sanded the whole plane, covered wheelbay-doors & bombbay-doors with 25 gr. glass-cloth, also some bottom parts of fuselage and nacelles.
End of Feb 2015; Made a moulding for vacuum forming the radial dummy-engines, and made a moulding to form the GRP engine-cowls, and formed them all.
 

Finishing the Model;
Now I can start finishing the model;
After a final sanding, everything was covered with lightweight,  Japan tissue (paper) 12 gram per square meter, and one coat of clear shrinking dope, and carefully light sanded. Then scale panels and so on were scratched- in, two more coats of clear shrinking dope and light sanded, a wash-primer was sprayed on, wet sanded and rivets were applied.

30 April 2015;  I have sprayed the model  in the colours, serial & Registrationnumbers are sprayed on, and all the parts has been assembled again (photos 133-134).

RADIO INSTALLATION;
At last my Graupner JR- MC24 (Hott 2,4 GHZ) radio equipment was installed again and I did need all 12 channels. Total 20 servos!! 2x Graupner Hott GR24 receivers + 2x Engel Powerboxen (I always fly my large scale models with 2 receivers: 1x for the right hand side and 1x for the left side!), 2 electronic switches, 6x LiFe batteries 2300 mAh (2x2=4 batteries for 2x Power Management System PMS-plus of Engel Modellbau, Germany). The 5^th and 6^th battery are for the electric retracts and retractable landinglights.

Fuselage servos:
Front; 1x retract servo-switch + 1x landinglights servo-switch + 1x nosewheel linkage control  
Rear; 2x elevator + 1x rudder  
Middle;  1x 180⁰ servo for Bombay-welldoors + 1x Bom Trapdoors  
=Total 8 servos.