Spitfire PR XI

1 year 8 months ago #1058 by Carl
I have started putting together the wings and it is amazing how quick the progress appears to be. The box is now more than half empty with more wood on the building board than left in the box. The wing center section has been glued together, the four ribs are all identical with the inner two reinforced with a ply rib. Unfortunately, these did not quite match the balsa ribs so some modifying was required. Also the dihedral braces did not fit into the slots of the ribs so this was remedied with a bit of filing. The wings are held onto the fuselage with a ply tongue instead of balsa dowels which is what I was expecting. Also, the wings are a traditional rib and spar construction but it is left as a partially open structure with a fabric covering. I plan on completely sheeting the wing with 1/16th balsa and then covering with lightweight fibreglass. This may add a little weight but it will make the wing a lot more durable over time.


I have started on the left wing panel and have glued all the ribs and spars in place, the final rib at the wing root requires a jig to be made to fit the rib at the correct angle to match the dihedral brace.

I was hindered in the photography by my little helper who was determined to get in a picture!

Once I had made the center panel I couldn't resist mating it with the fuselage to get an idea of how it will look.




The canopy has been trimmed to roughly fit at the moment and the cockpit floor has been painted black. The undercarriage will be fixed as that is how it comes in the box! The next major job is to sheet the fuselage which with all its contours will take a bit of planning beforehand.
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1 year 8 months ago #1064 by Carl
I have not made much progress this week, i have remodelled the rudder/fin to the PRXI shape but that was only a small job. Time for a little more history of the PR Spitfire! The development of the PRXI was delayed primarily due to delays in the MK VII and MK VIII. As a result production of PR Spitfires continued with a Merlin 60 powered Spitfire based on the Mk IX. Production of all PR Spitfires was further threatened in 1943 by an Air Ministry proposal that all PR units should convert to a PR version of the Mosquito. This was modified to an assertion that 90% of PR work could be accomplished by the Mosquito with the remainder done by PR variants of the Spitfire. This proposal could have seen the end of significant development of the PR Spitfire. It was the head of Coastal Command AIr Vice Marshall John Slessor who pointed out "The Spitfire was smaller than the Mosquito, used half the number of Merlin engines and was faster, more manoeuvrable and quieter and, therefore production should be increased, not reduced." A timely intervention that struck a chord with the Air Ministry, particulalry the savings on Merlin engines! The Air Ministry then reversed its decision and accelerated development of the PR XI at the expense of the Mk VII and Mk VIII fighter variants. Production of the PR XI continued until December 1944 when production ceased in preference to the PR XIX. A total of 471 PR XI were built.
Photographic reconnaissance was carried out at the beginning of the war by a variety of units. The first was called the Heston Flight, a civilian organisation set up by MI6 just prior to WW2 to photograph areas of Europe using civilian registered Lockheed 12A aircraft. The Heston Flight was renamed the No 2 Camouflage Unit on 1 Novemeber 1939 then in January 1940 it became the Photographic Development Unit. June 1940 saw it renamed the Photo Reconnaissance Unit then finally in November 1940, No 1 Photographic Reconnaissance Unit. The aicraft that were used were various and included the Spitfire, Bristol Blenheim, Lockheed Hudson and De Havilland Mosquito.
It was in October 1942 that No 1 PRU was disbanded and all the aircraft were reassigned to five Squadrons, 540, 541, 542, 543 and 544! All Squadron were based at RAF Benson. It is at this stage that our interest turns specifically to 542 Squadron and the arrival of Flt Lt Gordon Puttick RAFVR. He had joined the RAFVR in March 1941 and was posted to 542 Sqn after his flying training. In March 1943 the Squadron was equipped with the Spitfire PRXI. The missions carried out by all PR aircraft were highly classified and the pilots did not achieve the fame of the traditional fighter pilots of the Battle of Britain. This all changed thanks to Operation Chastise and the stunning achievemetns of 617 Sqn in destroying two damns in the Ruhr valley. All major raids were preceded by a mission flown by a one of the PR squadrons who would photograph the intended target to accurately determine the need for its destruction. They would then return to the target as soon as possible after the raid to assess whether the target had been destoryed and whether the bomber boys would have to revisit the target. As most bombing raids were carried out at night, the PR aircraft would take off just before dawn to arrive over the target at first light and take thir photographs. They would then speed back to RAF Benson where the cameras were unloaded and the film taken for immediate developing and then onto the Photographic interpretation branch. The photos were often flown aroung the country by the PR Sqns themselves to all the various units that needed to see them. The first photos taken of the Damns were by Flying Officer Frank "Jerry" Frey of 542 Sqn. The following is a description by him of that mission:

"When I was about 150 miles from the Möhne Dam, I could see the industrial haze over the Ruhr area and what appeared to be a cloud to the east. On flying closer, I saw that what had seemed to be cloud was the sun shining on the floodwaters. I looked down into the deep valley which had seemed so peaceful three days before [on an earlier reconnaissance mission] but now it was a wide torrent. The whole valley of the river was inundated with only patches of high ground and the tops of trees and church steeples showing above the flood. I was overcome by the immensity of it."

Churchill was quick to recognise the immense propaganda value of the photographs and allowed them to be published in the papers along with a picture of Jerry Fray. It was the only time a PR pilot achieved recognition during the war, their names were kept secret from the public. Two more flights were made by 542 Sqn over the damns that day. One of them was flown by Flt Lt Gordon Puttick.Obviously, the Germans were alerted to possible follow up attacks and reconnaissance so these flights must have been incredibly dangerous. To fly alone in an unarmed aircraft over an enemy who were on high alert and very angry must have taken a great deal of courage.

Many years later, Gordon Puttick planned on building and flying a replica of the Spitfire that he flew during the war, sadly he did not get to build the model and it was passed on by a friend of his to AMARC. I have yet to find out exactly which aircraft he flew over the dams but I am confident it was a PR XI of 542 Sqn so eventually I hope to narrow down the registraion of the aircraft.
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1 year 7 months ago #1067 by Carl
I am reaching the stage at which nearly all the wood in the box has been used up! I have joined all of the wing sections together and have made the wing leading edge. I was expecting it to be a tricky job but it was relatively straightforward, It was a lamination of three layers of balsa strip aech glued into place before the next lamination is applied creating the graceful curve typical of the Spitfire wing.







Once the wing leading edge was complete I couldn't resist putiing it all together to see what it looked like.








The method for making the ailerons is to build the wing then cut out the ailerons from the wing ribs. This proved to be quite tricky, the main problem being to retain a consistent angle where you cut the wing ribs to create a new trailing ege.






I am rapidly approching the point where I can no longer delay sheeting the fuselage, particularly as the Spitfire has some interesting contours around the engine and fuselage sides! On a slightly differnent note I am due to return to work next week as my hand injury has recovered ok. I will try and cram in as much building as I can in the next few days as the building rate will inevitably slow once I am back at work.
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