A project of the scale and complexity of our P51D project here at Ohakea has lots of dimensions and involves a lot of good people here and around New Zealand who make things happen. We started the project by developing a detailed project plan covering every aspect and task ahead of us and this has guided us since. The project has been sliced up into numerous sub projects and tasks – all requiring planning, management and skill.
The glazing of the main windscreen assembly is one such task which has been managed through to completion by Joe Deere. When we went through the P51 spares that John Smith had accumulated, we found we had two brand new laminated side windows still in their original packing and also a brand new bullet proof windscreen. They were brand new but also 80 years old and all had begun to delaminate around the edges and this would only get worse. We investigated available ways to reproduce the laminated glass but it simply wasn’t feasible, so we turned our attention to using Perspex to achieve the same end.
The two original side windows were used to make accurately shaped formers which our sub contractor used to form the shaped side windows. For the main windscreen we used the original North American Aviation drawing to CAD/CAM the windscreen from Perspex the same thickness as the original 8 layer laminated glass and all three windows are now sealed in place. All done with good Kiwi ingenuity with the help of two New Zealand based sub contractors.
The original gun sight controller has been fitted and attached to this is the original airspeed correction card dating from its last update in May 1956. A new one will replace this when the time comes for the rebuilt aircraft but in the meantime it’s a nice direct connection back to its last year in RNZAF service at RNZAF Base Ohakea.
This week we have been busy with a range of smaller tasks, all important in moving the project forward towards completion. Amongst other tasks, Brian and Joe have been preparing the rudder to travel down to JEM Aviation at Omaka for fabric covering by resident guru Marty Nicoll. David Thayer was back with us today making progress on wiring the first of the wings.
Pete has been working through refurbishment of the ammunition bay doors and items that go in the ammunition and gun bays. Interesting find on one under the silver paint was part of the original US markings. Odegaard Wings have sent back to us any wing skins that had RNZAF markings on them so we can display these in the future. Joe has also been fitting the complex panels that sit behind the radiator area where it blends back into the rear fuselage.
More cowl related items are back with us now in their final High Speed Silver. We are also working with Nathan Bosher at the Air Force Museum of New Zealand to formulate the correct colours for various aspects of the final markings. This area is a bit of a minefield as there was considerable variation in what was applied throughout the service life of the Mustangs as well as considerable regional variation. Our aircraft also had the inside of the clamshell gear doors painted a shade called “Ohakea Green”.
It’s a long weekend here in New Zealand as Monday is a public holiday to mark the life and service of Queen Elizabeth II. I thought it would be timely to look back on the last two years of our Mustang project and select a few random images to mark passing the two year point on the project. It’s been a fascinating journey so far and we have learnt a lot on the way.
We now have most of what we need to finish the aircraft on hand at Ohakea although there is always potential for surprises. All of the hydraulic items for the aircraft have been overhauled and tested and most of the electrical items are in place.
This week the focus has been very much on wing related tasks. The clamshell undercarriage doors have been disassembled for refurbishment with the inside skins still showing the distinctive “Ohakea Green” applied to them. Rebuilding of the armament bays is well advanced and we have been test fitting the rocket rails.
More and more parts are now in their final High Speed Silver finish ready for final fitting to the aircraft. We have also been assembling the “nut channels” that hold the stress panel doors on under the wing tanks.
Fitting out of the systems in the wheel bays has started and when finished these are a very busy and complex part of the aircraft.
Another key milestone was reached this week with the joining of the two wing halves into one assembly. We have also been trial fitting the rocket and bomb mounts onto the wings as well as completing more of the ammunition and gun bay fitouts.
The large clamshell doors are being rebuilt with replacement outer skins, a tricky job because of the tight fit of the doors when closed. The wheel bays are starting to get a little busier but still a long way from how busy they will end up when fully fitted out.
The main canopy has been test fitted to also check out the running mechanism. The canopy is already in its final High Speed Silver finish.
Michael O’Leary’s book “Building the P51 Mustang” (2012) is a great photographic record of the construction of Mustangs at the Inglewood and Dallas factories and is a fascinating insight into mass production of an aircraft like the P51. The differences in construction with the Spitfire are quite noticeable and represent effectively a generation of aircraft apart. Whereas the Spitfire was by design a labour intensive, hand built aircraft and represents a complex restoration project, the P51 is clearly an aircraft designed from the start for mass production and this translates through to being an easier aircraft to rebuild.
The Dallas factory where our P51D was built, at its peak, had a workforce of 34,000 working 24/7 which had reduced to around 15,000 by the time our Mustang was built. All of this supported by a large array of suppliers and sub contractors feeding into the factory - such as Bendix who supplied the undercarriage legs and Goodyear who supplied wheels and brakes. Many suppliers such as Bendix and Harrison (who supplied radiators) were either part or wholly owned subsidiaries of North American Aviation’s parent company General Motors.
Production of the Mustang was very clearly separated into the fuselage and wing assemblies and these two assemblies were taken through to completion before a wing assembly and fuselage assembly joined to become an aircraft near the end of the production line. We are following a similar process with our efforts now focused on the wing assembly.
The remaining tasks on the wing can broadly be separated into armament bays, undercarriage bays/assemblies and control cable runs on the back of the wing – amongst a myriad of other smaller tasks. Virtually all the sub assemblies for the armament bays are ready to install including the complex rear gun mounts which were used to sight and adjust the guns. We have some of the original placards mounted on the inside of the front gun bay doors and will tidy these up a bit and fit these imperfect originals.
One of the interesting aspects of the Mustang design is that effectively there is no bottom to the cockpit section of the fuselage – at the moment its just one gaping hole. The plywood floorboards and control column assembly are in fact mounted to the top of the wing centre section. This week they were all trial fitted to allow drilling out of the pilot holes in the wing centre section. Rebuilding of the clam shell doors is another task progressing along as well.
Fascinating that the A/C controls are on the "cabin floor", I guess leaning down to turn on the defroster wouldn't be the most of your issues if one's windshield is already frosted up. Seeing the joystick like that reminds me again of P-40s construction if I'm not misremembering.
Rocketry and bombing were regular exercises for the TAF squadron Mustangs. There was also an annual weapons camp at Ohakea where all of the TAF squadrons brought their Mustangs to for extra formal training in these arts