Greg Batts’ work on the CAC Boomerang “collection” in Brisbane continues. Regular readers will recall that at present, four CAC Boomerangs are being worked on within the workshop and work has progressed on all four over the past 3 months.
CAC Boomerang A46-249
A46-249 is a CA-19, (last Boomerang built by CAC), being worked on for The Old Aeroplane Company of Tyabb Victoria. With the timber fuselage shell now cloth covered, it is about to be painted in primer before being fitted with the assorted metal work required for attaching various panels, canopy rails, and doors. Both the rear tubular frame and cockpit section are repaired. The whole assembly is now to be blasted/ primed and painted so that additional internal fuselage work can continue at the Brisbane workshop and later at Tyabb.
CAC Boomerang A46-77
A46-77 is a CA-12 being worked on for a Mareeba, Queensland owner. Work continues on this aircraft with the complex firewall fitting going ahead. This is always a tricky phase in any Boomerang restoration, as the original firewall was alloy construction and was not that effective in shielding the aircraft in the case of an engine fire hence the requirement for a stainless steel replacement which shields the aircraft and pilot in case of an engine problem. Stainless steel is notoriously difficult to work with and as each Boomerang is slightly different every firewall has to be constructed individually – not an easy job. The complex Radio Shack is structurally completed ready for the Perspex. Once all the forward fuselage work is completed, the aircraft will have the fuselage shell removed again and work will commence on fitting the rest of the internal fuselage components. The center section will be reworked and attached and the undercarriage fitted so that it will again sit on its landing gear. All the over and behind wing fillets have finished, being wheeled by Grant Wahrlick and will be sized onto the aircraft when the center section is in place. With the aircraft sitting on its undercarriage focus will then be on final assembly of components before it departs to its owner for completion.
CAC Boomerang A46-92
A46-92 is a CA-12 and is owned by a syndicate and is in the early stages of restoration. The components of the fuselage are currently in the workshop being worked on for restoration to commence in earnest. Frame repairs are underway and the lower rear monocoque pan is ready for the frames to be mated. Once that occurs, the completed wooden covering will be attached for the cloth covering to be completed. Once A46-77 is on its wheels it will be “swapped” to the space currently occupied by A46-92 and this will allow the fuselage of A46-92 to be completely restored in the same manner as the other Boomerangs and progressed toward airworthy status.
CAC Boomerang A46-54
Lastly, in this update, work has moved on apace with Greg’s own Boomerang CA-12, RAAF serial A46-54. Much more of the electrical and hydraulic fit out has been done and the fuselage fit out is close to completion many of the red painted template hoses and hydraulic lines have now been replaced with the newly manufactured “operational” items.
The cockpit is also proceeding well to completion, with most of the equipment either fitted or about to be. However the most striking feature of the work carried out since our last visit is the work being done in preparation for the fitting of the engine which is a complex and time consuming process. We asked Greg what has to be done and he sent an email to us detailing the stages for the mounting of the power plant titled “But why is it taking so long”.
- “To fit the engine you first have to fit the cowl gill assembly to the back of the engine, as you can’t get in/on later.
- But before you install it all to the mount you have to install the exhaust collector ring and connector stubs as you can’t get it in/on if the engine is in the mount.
- But before that you have to install the tank bay doors as stress panels to avoid spar spreading with the weight of the engine assembly.
- But before that you have to install the two fuel tanks as you can’t close the doors if the tanks aren’t in.
- But before that you have to install all the fuel tank bay plumbing and undercarriage locking release assembly both sides as you can’t get to it all if the tanks are in.
- But before that you have to install the 2 undercarriage outrigger frames as you can’t get to the attaching bolts internally with the tanks in.
- But before that you have to install the retract rams to the outriggers to assure alignment of the rams to the lifting pin on the undercarriage leg.
- But before that you have to overhaul the 2 retract rams.
- But before that……….”
But why is it taking so long????
So there is the answer. It’s no easy process and almost a poem in its own right!
Greg is now wading through the above process and is quite advanced as can be seen from the photographs. Of particular note is the fitting of the exhaust collector ring and exhaust pipe itself, which is quite large and imposing. In addition, quite a lot of the “plumbing” including tanks and reservoirs have been installed in front of the firewall, as well as fuel lines and air vents. The fuel tanks themselves are now ready for fitting and are more or less the same as fitted to the North American T6/Harvard series of aircraft. However, they require a special CAC manufactured sump assembly to allow for a higher rate of fuel flow, given the much larger and more powerful engine.
So quite soon now, after a mountain of work the Pratt & Whitney R-1830-90 Twin Wasp 14 Cylinder radial engine of 1,200 hp (895 kW) will be fitted. Regular readers will recall that this engine has already been overhauled and is ready to go. It is expected that this process will be complete prior to Christmas.
It is easy to forget that the Boomerang is a complex fighter and is fitted with far more systems and unique components than the CAC Wirraway. In fact, there is far less commonality between the two aircraft than is generally thought to be the case. Boomerangs are therefore, a more time consuming and “bespoke” aircraft to restore, requiring someone with detailed knowledge, skills and experience to fully restore, especially to flying condition.
Warbirds Online will continue to follow the restoration process of these aircraft being undertaken by Greg Batts of Combat Aircraft Constructions as they move through the workshop. Of particular interest is Greg’s Boomerang A46-54 as it nears its first flight in the not too distant future.
© John Parker 2015