It is generally accepted by aircraft enthusiasts that the Spitfire was one of the most beautiful aircraft ever built. This is largely due to its flowing lines and gentle curves throughout.
From a restorers point of view, these same lines make it a somewhat difficult to rebuild, and certain parts can be a nightmare to reproduce with the usual equipment found in the average sheet metal workshop.
Further complicating matters is the fact that throughout its development life, many of the various marks were achieved by taking an existing mark of aircraft and adding or “tweaking” bits as an “interim fix” to achieve an overall performance increase. However, in a few cases the designers did start with a clean sheet of paper, and the process of modification started again.
Spitfire restorations will really soak up the hours, with a figure of 35,000 to 40,000 now becoming the generally accepted norm. Of course this will vary with how the hours are actually counted, or accounted for . i.e. are the hours spent on parts sourcing and research included.
Mh603 has been around for quite a while, having been started in the UK back in the 1980’s and subsequently sold to the USA, where restoration work continued on and off for a few years. The aircraft was again put up for sale in 2009, and was purchased by Pay’s Air Service. At that stage it was essentially an ( outwardly ) completed fuselage and empennage, with the balance of the project as a kit of individual parts and minor sub assemblies. The container arrived at Scone aerodrome in late 2009, and restoration at scone commenced in March 2010.
One of the first tasks carried out was to perform a detailed assessment of what was there, what needed further work, and what was missing. Unfortunately, it was soon discovered that the aircraft was far from complete, and a lot of effort was needed to be put in to sourcing the balance of the parts.
Early on it was decided to restore the aircraft as authentically as possible, and this includes the use of appropriate British hardware. At some stage, a lot of American fasteners had been installed, and these have been replaced with the correct items. The correct British “purple” rivets will be used throughout, although these are now becoming quite hard to come by, and can be expensive. In Spitfire rebuilds, rivets are generally replaced as a matter of course, because in the factory, Supermarine drawings gave the option of either the high- magnesium, or low- magnesium rivets as able to be used, and after 70-odd years, there is really no way of knowing which type was originally installed. Therefore the prudent course of action is to replace all the rivets, regardless of how sound the joint still appears.... and there are a LOT of rivets.
Typically, when a restoration is commenced, the first part to be tackled is the Fuselage, and MH603 has been no exception, as this was where the most of the effort prior to arrival had been concentrated. The documentation ( the dreaded paperwork) accompanying the kit of parts was minimal at best, so to establish a firm basis to continue on from, and to substantiate the work done to date, extensive NDT and material analysis was carried out. Fortunately, this proved that nearly everything was as it was claimed to be, with only a few parts having “ question marks “ against them. These parts have been subsequently replaced with new items.
The stub spars that the wings attach to ( also called carry-through spars) were replaced with new items as a matter of course.
Also, we had become aware of murmurings among the Spitfire community that the fuselage structure was out of alignment. This was checked and it was discovered that the rear wing attach points were slightly out, along with the stub spar position. This was rectified when the spars were replaced, along with the fwd fuselage skins being renewed. The four main attach points for the engine mount were also dismantled and inspected, with several items replaced in the process.
The cockpit area is another area that has a few problems, with the Right hand canopy rail not extending far enough forward, necessitating the replacement of that rail and the adjacent skin.
Lastly , a couple of the fuselage frames had incorrect profiles, and replacement frame sections have been sourced. A couple of aft fuselage skins are also being replaced, to give a neater joint where the tail unit attaches.
Over the 2012 Christmas period, the fuselage was externally taken back to bare metal, corrosion protected with alodine and repainted with epoxy primer. The internal surface of the fuselage was rubbed back and repainted in silver ( aluminium ) colour. The exception being the immediate cockpit area, which is almost always green. This was repainted with a slightly different shade, as matched to a paint sample from the original aircraft.
A new instrument board has been made, as well as a new cockpit ventilator system.
The seat and its mount/ adjuster mechanism is complete, but need some minor cosmetic rectification before it is fit for use. A new leather seat back padding has been made as per original configuration, even including some original kapok and horse hair filling.
The fire baffle between the cockpit and fuel tank was largely missing. The task of producing this assembly was placed in the capable hands of Pioneer Aero Ltd, and the kit of parts for this unit is now largely complete.
Canopy and windscreen.
Only the canopy Perspex bubble and a few minor sheet metal parts arrived with the kit. The incredibly tricky canopy forward frame has been reproduced ( plus a few spares ) and the remainder of the canopy items are in the process of being sourced or made locally, including the latch and jettison mechanism.
The windscreen assembly has been dismantled, assessed and is currently being reassembled with new side panels being made in house. The manufacture of the laminated glass forward screen has been outsourced locally, and is due for installation shortly. A rear vision mirror is still required.
Upon arrival the wings were essentially a largely incomplete kit of parts, having originated from multiple sources.
One of the main concerns was that the spar booms were part of an early batch that had been made from material of insufficient strength. Fortunately, as the booms were not built into any structure, it was a relatively simple process to send them back to the UK to have them heat treated up to the required strength. They now have no flight limitations on them, and are installed in the leading edge assemblies.
The 2 wing leading edge assemblies ( also called D- boxes because of their cross section) are now almost complete, with the skins being drilled off and trimmed for the final time before being riveted on permanently.
We have been fortunate to be able to have the use of an original set of leading edges, from which an assembly fixture was made. This has enabled us to keep everything aligned during assembly, and ensure that the correct washout is maintained. The spitfire has about 2-1/2 degrees of washout, and with its elliptical wing, this is quite tricky to measure. The spar is built flat and the angle that the ribs are attached to it progressively changes along its span.
The D-box rebuild is incredibly fiddly and time consuming, with a lot of double and triple handling involved. In itself, it actually consumes almost half the labour and materials cost of the total wing rebuild, although at first glance this would not appear to be the case. The trailing edge structure from the main spar aft is relatively straight forward by comparison.
There is now a complete set of ribs on hand, with the missing parts either made in-house or sourced elsewhere.
A complete set of wing flaps is now on hand, as are the radiator fairings and flaps. The wing tips are complete, only requiring cosmetic rectification in the leading edge area. The special attach hardware for the tips are now on hand.
The ailerons, however, produced a problem which we weren’t expecting. At first glance, they appeared to be complete and ready to fit. A quick assessment revealed that they were in fact the “short span” type, as fitted to the MK8 and Mk14 aircraft, and therefore will need to be lengthened by some 10 inches. To achieve this a new spar will have to be installed, along with several new ribs and skins. Fortunately, these parts are now sourced and on their way to us.
The wings will have the required modifications to allow the use of “straight” axles, and it is envisaged that they will also be modified to incorporate fuel tanks in the gun and ammo bays, as per the TR9 Spitfire.
Recently, we were able to acquire a very rare genuine Spitfire bomb carrier mechanism. A pair of these will ultimately be fitted to the wings of this aircraft, and the standard wing tank configuration will be altered slightly to accommodate the internal wing structure required for these.
Airframe Assemblies Ltd in the UK is currently producing a wing to fuselage kit for the aircraft, and it is envisaged this will be on hand for when the wings are mated to the fuselage.
The tail portion of the fuselage is largely complete, with the exception of some cosmetic rectification required. Missing minor brackets and parts have now been sourced, with only the tailplane to fuselage fairings to be made.
The 2 halves of the tail plane are complete, however the special attach hardware still needs to be sourced. The elevator and rudder are both structurally complete, and only need covering and finishing. This will be carried out nearer to completion of the project.
Very little of the parts required for the aircraft hydraulic, pneumatic and flight control systems arrived with the aircraft. However nearly all the required parts have now been sourced or made. All the stock Tungum tube for the pipework is on hand, as is all the connecting hardware, although some of this is now hard to find.
A full set of flight control cables and attaching parts is on hand, as is most of the mechanical system parts for the flight controls
The rudder control system has been completely dismantled, NDT’d re-cadmium plated and reassembled. The support structure for the flight control components has been completely rectified or replaced as necessary. In this area, a bit of “artistic license” had been previously used with some replacement parts of incorrect configuration and spec being used. These areas have now been rectified by the use of new correct items.
A complete set of oil and coolant pipes has been completed and on hand, and work is now underway on the associated brackets and connections.
Instruments and electrical.
Again, very little arrived with the project, but the majority of the required parts have been sourced.
On hand is a fibreglass replica of the original radio mast, with a modern aerial for the emergency locater installed inside. An original under wing IFF aerial has been sourced, and this will be used with the modern VHF radio, maintaining a stock outward appearance. We are always on the lookout for instruments and electrical items, as usually several items of one particular unit are required before a serviceable ( airworthy) part can be assembled.
A complete set of landing gear components are on hand. However, the outer cylinder for the right hand main gear is corroded, and a replacement item is being sought. New original tubes were found on site !, and original tyres have been sourced. Complete NOS brake units are on hand too, as well as new drums, yet to be fitted to the new wheels. New retraction ram assemblies currently being manufactured by Supermarine Aero.
A set of blank panels for the cowls, and some of the reinforcing structure arrived with the kit. The missing parts for the panels themselves have now all been either made in-house, or sourced from overseas. A complete kit of parts for the cowling support structure has now been sourced.
A new carburettor air box has been manufactured, as well as a couple of spare items made for trading purposes.