With the rear fuselage complete, RB396’s rebuild is now progressing with reconstruction of the tailplane. This is the first of regular progress reports that will be posted here on our website and charts the work done over the first two months of this section of the project.
If you are a supporter, you should have already seen this in the latest newsletter that was sent out a few weeks ago. Hearing about things first is just one of the benefits our supporters receive as a thank you for their dedicated support.
As previously confirmed, the Aircraft Restoration Company (ARCo) needed to make some adjustments to the tail jig. The jig was originally constructed for another tail, and although all tails should, in theory, be identical, they were effectively hand-built – so slight differences were expected between our tail and the one the jig was made for.
A trial fit of our tail in the jig revealed that adjustments were needed to the fixing points for the tailplanes and the alignment of the rudder post. These alterations were completed during September, and the tail section now sits squarely and securely within the jig.
ARCo proposed a much more significant alteration to the jig to aid the rebuild. This involved:
- Removing the upper tail fin framework (originally made for a Tempest tail fin rather than a Typhoon).
- Attaching stiffeners to keep the jig square.
- Mounting the lower half of the jig on a rotisserie structure so the entire lower tail monocoque can be rotated for better access during the rebuild.
As you may recall, the much larger jig for the rear fuselage was constructed in a similar rotatable format.
Before removing the upper tail fin framework, splice plates were made so it can be easily bolted back on later and adjusted for a Typhoon fin once ready. The new stiffeners can then be removed.
All this jig modification work was carried out during September.
Tail Rebuild
The jig enables the main structural elements of the tail – such as frames and diaphragms – to be removed, refurbished, repaired, or replaced individually, while the rest of the tail remains securely in place. This approach saves considerable time and effort by maintaining precise alignment and positioning without needing to build a separate jig for each component.
However, this method also means that only one or two items can be removed at a time to preserve the structural integrity of the tail. Each part must be reinstalled before the next can be removed. As a result, visual progress can appear slow compared to dismantling everything at once.
Although much of September’s effort was focused on the jig, ARCo also began work on the lower tail monocoque rebuild during the month.
Firstly, the fin and upper port skin were removed. This allowed an internal inspection of the tail and the upper diaphragm. As you’ll recall, we had hoped to inspect MN235’s internal tail construction for reference, but the RAF Museum confirmed this will not be possible until mid-2027. That inspection would have confirmed the internal structure and helped identify any missing parts once our tail was opened. Fortunately, the internal inspection confirmed that all internal structural elements are present.
Research was required into stringer 7, as this type of “T” stringer is not used in the rear fuselage, and we did not have a drawing specifying which A.Std it followed. Hawker used standard brackets, extrusions, and procedures across all aircraft, recorded in the A.Std document containing 2,352 drawings – some of which are missing. Measurements of stringer 7 were taken and compared against all A.Std “T” sections until the correct one was identified. This process took some time.
The upper diaphragm, including its brackets and extrusions, along with the intermediate frame bulkhead, has been removed. Although the goal is to reuse as much original material as possible, corrosion inside the tail affects most components, meaning many will have to be remade. The original parts, however, are strong enough to be used as patterns, and with the available drawings, ARCo has a solid starting point.
ARCo is now using the last of its British-spec L163 aluminium stocks for this project but will soon need to switch to American-spec 2024 material, as the British specification is now largely obsolete.
New items manufactured to date:
- Upper L/H angle
- Top diaphragm
- Top diaphragm forward attach angle to rear spar
- Upper intermediate bulkhead diaphragm
- Attachment angles (port and starboard) for upper intermediate diaphragm
- Port side plate
- Starboard side plate.
During October, work continued with the removal of the tail leg and surrounding structure. Due to damage and corrosion of the main attachment pin, the tail leg could not be removed without risking distortion to the surrounding framework. The decision was made to remove the entire cradle section, including the tail leg, from the monocoque.
Once removed, better access was gained to the main attachment pin. With the use of additional penetrating oil and some heat, the pin was successfully extracted, allowing the tail leg to be separated from its cradle.
As we did for the rear fuselage, we have set up a timelapse camera on the tail and you can see the first couple of months’ work in the link below.
ARCo now plans to concentrate on the cradle subassembly so it can be refitted into the monocoque before moving on to the next phase of work.
Tail leg cradle with new parts under manufacture
During October, work continued with the removal of the tail leg and surrounding structure. Due to damage and corrosion of the main attachment pin, the tail leg could not be removed without risking distortion to the surrounding framework. The decision was made to remove the entire cradle section, including the tail leg, from the monocoque.
Once removed, better access was gained to the main attachment pin. With the use of additional penetrating oil and some heat, the pin was successfully extracted, allowing the tail leg to be separated from its cradle.
As we did for the rear fuselage, we have set up a timelapse camera on the tail and you can see the first couple of months’ work in the link below
ARCo now plans to concentrate on the cradle subassembly so it can be refitted into the monocoque before moving on to the next phase of work.
An interesting discovery was made following the removal of the tail leg cradle—the original tail unit data plates were exposed.
It is thanks to our supporters that we have been able to commit funds (£10k per month) to allow the engineers from the Aircraft Restoration Company to work on the tailplane three days per week.
More funds would, of course, enable us to buy more engineer time and complete this next stage sooner than our projected two-year target. Please use the link below to see the supporter options.