One item which has held us up for some time is the manufacture of "top hat" stringer sections. These are needed to replace all the missing ones in the centre wing and with a very slightly narrower section to act as joiners for all the bent stringers we had to cut out of the rear fuselage. Fortunately, the same section is used in every location in the Bolingbroke. We had looked at the possibility of obtaining rolled sections but the costs involved were significant. One of our volunteers investigated making them individually by hand as the longest length needed is about 18 inches. This has proved to be successful although somewhat time consuming. The two photos below show part of the manufacturing process and a finished length of stringer.
During the recent summer we had the inside of the rear and stern fuselage cleaned by using solid carbon dioxide. This has the advantage that there is no cleaning agent left for subsequent removal - only the residue of dirt and paint dust which can be removed by vacuuming. The residual surface is ready for a new primer coat.
The picture below shows the CO2 company in action inside the rear fuselage. The equipment was also used to successfully clean the exterior of the Bristol 173 twin rotor helicopter which had a lot of surface corrosion.
Following the cleaning the inside of the forward end of the fuselage was sprayed with primer as seen below. The photo also shows the rear fuselage mounted on the new rotation trolley which we made from the timbers used for the platforms which brought the Bolingbroke back to the UK.
The trolley is similar in design to that used for the nose fuselage and allows us to tilt the fuselage onto either side so we have access to the underside. Steps have also been built from the platform timbers to allow good access to the interior and are shown in a later photo.
Subsequent to setting this up we realised that it would be much easier to work on the fuselage than it would be once it is joined to the centre wing so we have put this section assembly stage back while we work on the inside and bottom surface of the fuselage.
Many repairs were needed to the first three frames in the rear fuselage and the next photos show firstly one of our volunteers riveting repair patches to one of the broken fuselage frames and then the rear fuselage with the repaired frames and stringers riveted in place.
One of the major missing parts from 9048 is the stern post. This component, about 4 feet long, is a complex geometry sheet metal structure that connects the extreme rear of the fuselage with the trailing edge of both the tailplane and the fin. Earlier in 2014 delivery of much of the old Bristol Aeroplane Company archives to the Bristol Aero Collection revealed the presence of about 1000 negatives of original Blenheim/Bolingbroke drawings. These are mainly assembly drawings and they have all been scanned into a computer. They don't cover all the areas of the aircraft but did include 5 drawings of the stern post with all the information to make an all new component. Prints have been obtained and the first components marked and cut out as seen in the next photo which shows one of the drawings of the main parts and the green primed components being marked out for drilling.
The fin which came with 9048 was not from 9048 but a much later production aircraft which had been built as a training aircraft from new and was without the provision for the anti-icing necessary for the maritime role of 9048. Adding the anti-icing rubber is not a problem but the heavily damaged state of the fin is. Brutal methods had been used to separate it from the stern post causing considerable damage to the skins and the ribs connecting to the stern post.
Amongst the original drawings was one for one of the broken frames shown below with the remains of the frame.
Not only was the frame broken but the RH end was entirely missing. The drawing has enabled us to completely straighten and repair the frame and make a new end strip, which following the drawing instructions is made so as to be adjustable on assembly into the fin/stern post joint. The other ribs have been similarly repaired as shown in the next photo where they are fitted temporarily in place.
The two photos below show the badly damaged top of the fin leading edge before and after repair. The second photo also shows the wooden tool which was used to reshape the damaged area. We were surprised to find that this leading edge component was actually made from two parts which had been welded together along the apex of the section so the reshaping had to be carefully done to avoid the welded joint splitting open.
Eventually this leading edge component will be covered in rubber to simulate the anti-icing strip used originally on 9048.
Both of the steel engine/undercarriage mounting frames have been stripped of all non-structural parts - these having been clearly labelled before removal as seen in the photo below. Minor repairs were needed to straighten bent brackets. It is intended that the frames will go to a local company for thorough cleaning inside and out before an anti-corrosion treatment is applied. Careful inspection suggests that there is only a light surface rusting.
The 7 ft long frames which carry the flap drive shafts in the centre wing have been repaired where necessary and then cleaned and prime painted. The photo below shows both frames - one before repairs and one after painting.
Another volunteer is busy refurbishing the access door which fits on the top of the rear fuselage adjacent to the gun turret. This came loose with the aircraft with half the hinge completely missing and also the lock mechanism. It was in very poor shape with lots of large dents. It has been completely dismantled and it was immediately noticed that the main skin panel was extremely light. A search through drawings we acquired earlier this year came up with a similar item as used on the Blenheim Mk. I but this had no window in it which seems to have been added by the Canadians. It also explained the lightness - magnesium alloy. Annealing this with a blow torch was seen as inappropriate but we soon found that the material was in fact quite soft and minor dents could be pushed out very easily with minimum effort. The missing half of the hinge has been made and once we have made the lock mechanism it will be reassembled.