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P- 5 1 SI E RRA SUE II

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SUE II

Highly original and restored in a manner to match, this combat veteran P-51D Mustang is a superb specimen WORDS: CHUCK CRAVENS PHOTOGRAPHY: DAVID LEININGER

n 8 April 1945, Lt Robert Bohna of the 402nd Fighter Squadron watched the morning mist dissipate as the temperature warmed at Advanced Landing Ground Y-32 Ophoven, Belgium. His squadron had been grounded by bad weather the previous day. Now the increased visibility allowed the 402nd to take off on an armed reconnaissance mission. Bohna flew the mission in a P-51K he’d named Sierra Sue. The unit’s monthly history report recorded: “Major Scales led us on our first mission of the eighth. Armed with 260lb fragmentation bombs we covered

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AEROPLANE DECEMBER 2015

the area Hannover, Celle, Brunswick [Braunschweig], Magdeburg, and Halberstadt. At Theide, south of Brunswick, we found an enemy column of 75 vehicles and damaged or destroyed all of them. Nearby we destroyed a locomotive and three light flak positions.” The furthest mission targets were about 230 miles (451km) from Ophoven. Along with 15 squadronmates, Bohna glide-bombed a patch of woods that photo-reconnaissance had identified as a hiding place for German tanks, trucks and artillery. At an altitude of 2,000ft, after pulling up from his bombing pass, his wingman

noticed coolant leaking from Sierra Sue’s scoop. Until then, Bohna hadn’t known he’d been hit by ground fire. Bohna throttled back and nursed the Mustang along on a westerly course, trying to make it over the lines. Near Gütersloh, Germany, Sierra Sue had lost enough altitude for Robert to know he was too low to bail out. He had to set the aircraft down. He found a flat farmer’s field and belly-landed the P-51. Despite the characteristic belly scoop ploughing into the ground, it slid along the field without flipping over. Robert wasn’t sure he’d made it past the front lines. Fortunately for Bohna, the area had been secured by Allied troops. He’d

ABOVE: P-51D Mustang Sierra Sue II in the hands of Paul Ehlen for a photoshoot accomplished during the EAA AirVenture Oshkosh show this year.

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P- 5 1 SI E RRA SUE II

ABOVE: A wartime image of 44-63675, showing crew member Dean Stitt standing with the P-51. VIA DOUG STITT AND JAY JONES

crash-landed less than half a mile from the 100th American Evacuation Hospital. There the surgeon sewed up his only injury, a minor scalp laceration. Three days later, he was able to return to his base at Ophoven, about 150 miles (241km) away. In fact, on 22 April Bohna’s own squadron ended up assigned to the base at Gütersloh, near where he had set Sierra Sue down. Now Bohna needed a new Mustang, and was assigned AAF serial number 44-63675 on 11 April. It was natural to name it Sierra Sue II. The machine was nearly identical to his first Sierra Sue with the exception of a Hamilton Standard propeller in place of the Aeroproducts one. Bohna flew this P-51D-20NA until the end of World War Two. It completed its last combat mission on 25 April, a B-17 escort mission on the last day that Flying Fortresses bombed Germany. They encountered three Messerschmitt Me 262s. Bohna spotted them first. In ‘Sierra Sue II: The Story of a P-51 Mustang’ (Xlibris Corporation, 1993), John Christgau relates the story as Bob told it to him. “He spotted [a] Me 262 far off. Without breaking radio

rush, even if the bullets went only halfway to the jet.” The Mustang Bohna flew was P-51D-20-NA ship number 516. It was rolled out of the North American Aviation factory in Inglewood, California, on 25 November 1944. The Army Air Force accepted it on 27 November and assigned serial number 44-63675. Shipped from Newark, New Jersey, it arrived at ALG Y-32 in the first week of April 1945 and joined the 402nd Fighter Squadron, part of the 370th Fighter Group, 9th Air Force.

v The war was effectively over for the 370th and for 1st Lt Robert Bohna, but one more notable flight occurred on 7 May. News reached the group at about 10.20hrs that German forces had surrendered unconditionally, and at 14.00 it staged a flypast of its aircraft in formation spelling ‘V E DAY’. The brevity of its combat career was a major contributor to Sierra Sue II’s survival. It is one of about 20 flyable P-51Ds documented as having actual World War Two combat time. Sources

‘The brevity of its combat career contributed to Sierra Sue II’s survival’ silence, he left the formation suddenly. There was no hope of catching the jet, much less getting a good shot at it. Still Bohna laid the pipper of his gun sight on the distant speck and pressed his trigger button. He felt his camera click on, and then Sierra Sue II shuddered as her six machine guns rattled. After weeks of little action, it gave Bohna a

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differ slightly, but most list the number of Mustangs currently flying at around 170. With the war ended in the European theatre, an order went out in early June 1945 that all Mustangs with fewer than 200 hours were to be grounded. Those airframes were ferried out on 19-20 June. The reason was probably

to preserve low-time fighters for later use in the Pacific. Although not a documented certainty, it is very likely that Sierra Sue II was among the Mustangs grounded at that time. After all, its squadron flew only 14 relatively short-distance missions after it went into service. 44-63675 ended up stored at ALG R-28, near Fürth, Germany. Later, all of the 402nd’s serviceable Mustangs were ferried to Fürth, to await disposal by the 10th Air Repair Squadron. With the surrender of Japan, any thoughts of continued combat in another theatre were over. Sue sat idle, along with hundreds of other Mustangs, exposed to the elements. Some were brand-new, un-used aircraft. It was one of thousands of fighters in Europe, once desperately needed, now surplus. When other governments came looking for aircraft to update their air forces, naturally they took the new ones first. It was almost three years before Sierra Sue II was to leave Fürth. The Swedish Air Force was modernising its squadrons by taking advantage of the inexpensive surplus Mustangs being disposed of by the AAF. It bought surplus P-51s and continued to do so until July 1947. The first 50 were priced at $50,000, but by the last lot the going rate was $2,500. It was in the final group that Sierra Sue II gained its reprieve from the smelter. It was a low-time airframe in relatively good condition. The aircraft “was one of the last thirty P-51Ds purchased by the Swedish government”, wrote John C. Taylor in ‘Swedish Mustangs’, published in the Spring 1968 issue of the Aviation Historical Society Journal. “The airplane had been standing outdoors for two to three years at Fürth and could not be flown to Sweden. Therefore, [the Swedish Air Force] Central Workshop (CVM) sent down a group of engineers and fitters to dismantle the Mustangs and have them sent home by rail.” Later, 44-63675 was taken by train to its new station outside Östersund, arriving in June 1948. There it was assigned to F 4 wing, becoming known as ‘Gul Kalle’ (its code ‘Yellow K’ in Swedish) and given the Swedish serial number 26152. The Mustang’s Swedish type designation was J 26. The former Sierra Sue II was transferred during 1952 to another unit, F 8 Barkarby near Stockholm. It was re-coded ‘Gron Kalle’ or ‘Green K’. The name Kleopatra was applied, making this one of very few J 26s to have any sort of personal marking. At F 8 it flew for two years as an officer’s time-building aircraft and squadron hack. By 1954, Nicaragua was looking for Mustangs to expand and modernize its air force and Sweden was transitioning to jets. Following its sale, serial 26152 was moved to Malmö, disassembled and shipped to Managua, Nicaragua.

AEROPLANE DECEMBER 2015

There it flew with the Nicaraguan Air Force (Fuerza Aérea de Nicaragua) from 1954 to 1961. Once its service was complete, 44-63675 was parked in front of the officers’ club at Los Mercedes air base as a gate guard for 10 more years. Most of the Nicaraguan Mustangs were purchased in 1963 by Will Martin and documented in his book ‘So I Bought an Air Force’, but 44-63675 wasn’t one of the 26 P-51s taken out of Nicaragua at that time. Will told me that 44-63675 had originally been part of his deal, but that the Nicaraguans switched it for a P-51 in much poorer condition. He suspected they would sell it for a higher price than the one he had negotiated. During 1971, a Californian named Dave Allender wanted a Mustang. A friend had spotted Sierra Sue II in Managua and informed Dave of the sighting. He found it still sitting in front of the Las Mercedes officers’ club compound. Dave commenced negotiations, and eventually a deal was made. The bill of sale records the transfer of 44-63675 from Coronel Orlando Villalta, acting as agent for the Fuerza Aerea Nicaragua, to David Allender Jr of San Mateo, California and is dated 30 July 1971. Sue was again dismantled and nine wooden crates were built to fit inside the cargo doors of a DC-6. The longer wing sections had to be sent separately to San Francisco by air. Most of the airframe was loaded up and flown to Miami, where Dave and a friend arrived a week later to pick it up in a Ryder rental truck. A week after driving back across the country to Hayward, California, Allender drove to San Francisco and retrieved the wing sections. Dave’s goal was to attempt to beat the closed-course piston-powered air speed record of 483.041mph set by

Darryl Greenamyer in 1969. Allender wasn’t interested in 44-63675’s history and probably never knew much about it. One of the young guys stripping paint from his Mustang before the speed modifications was very interested, though. Fortunately for later restorers, that 18-year-old, Lou DePropis, took notes of the numbers he found. More

physician. He based his P-51 at Flying Cloud Field in Eden Prairie, Minnesota. Doc Christgau owned it for 34 years and flew it for most of that time. He was well known at airshows around the Midwest for wringing out his Mustang. Doc was of Swedish heritage, so when he repainted the aircraft in

‘Small details set this restoration apart from previous Mustangs’ amazing is that Lou kept those notes, which were extremely helpful in tracking the history and demonstrating the provenance of Sierra Sue II. To get the Mustang up to near 500mph at low altitude, extensive changes were made. The outer 3ft of the wings, or wing extensions, were unbolted at the existing spar joint and removed. A foot was taken off the stabiliser. The angle of incidence of the wing was reduced and the wing leading edge made of fibreglass to smooth the surface and reduce drag. A fibreglass Horner wingtip was added. The turtle deck was straightened and a tiny smoked Plexiglas bubble canopy fitted. Dave specified that the canopy be large enough to wear a hard helmet, unlike Greenamyer who had used a simple leather helmet.

v It took two years for Sierra Sue II to once again stand on its gear. The Merlin was modified to try for 3,000hp, and between 1973 and 1975 several flights were made to try to get the modified machine working reliably. No attempt on the record was ever made, however. Dave decided to sell 44-63675 in 1977. It was purchased by Dr Roger Christgau, a Minneapolis-area

Army Air Force colours he had some of the Swedish markings painted on the starboard side. That side of the rudder displayed the yellow ‘K’ that was applied in Sweden and the name ‘Gul Kalle’. Paul Ehlen, another Minnesotan, knew Christgau well and often flew in the aircraft with him. He knew the history of Sierra Sue II and wanted to preserve that story. Over the course of five years, Paul tried to convince Christgau to sell the P-51 to him. In the summer of 2011, Doc finally agreed. It wasn’t an easy thing for him because the Mustang was a big part of his personal identity. The deal was finally agreed inside a car queuing at a Dairy Queen drive-up window in Austin, Minnesota. A send-off event was held on 17 July 2011 to celebrate the many years that Sierra Sue II had been flown in and around southern Minnesota by Christgau. Paul entrusted AirCorps Aviation of Bemidji, Minnesota with the restoration of his rare combat veteran P-51. AirCorps Aviation is a relatively new business, but it is owned by four men with extensive experience in restoration and maintenance. Erik Hokuf has 11 years in the field, Mark Tisler has 25, Dan Matejcek nine and Eric Trueblood seven.

BELOW: Sierra Sue II on the 370th Fighter Group flightline in Belgium. VIA JAY JONES

ABOVE: Caption CREDIT

P- 5 1 SI E RRA SUE II

ABOVE: The splendidly-restored Mustang won the Reserve Grand Champion Warbird prize at Oshkosh this summer.

Early on, the decision was made to restore Sierra Sue II to the way it would have looked in Belgium right after the nose art and lettering were painted on at the 402nd FS. By that time fighters were no longer being completely painted, so Sierra Sue II is bare-metal other than the wing paint North American put on over the ‘aerodynamic smoothing material’ to attempt cleaner laminar flow. This was not to be a polished, mirror-finished airshow aircraft. Rather, Sierra Sue II was to have mill-finished skins with the inevitable scratches and dull areas where an acid wash was used at the factory. It is in the precise colour scheme and squadron markings worn in Belgium and Germany during the war. During disassembly, the guys at AirCorps inspected every part and classified them into categories of ‘usable’, ‘in need of replacement’ and ‘missing’. Every piece that could be used or repaired went back into the Mustang. Often, repairing an original part was more expensive than making a new one but was done anyway. According to AirCorps Aviation manager Erik Hokuf, 90 per cent of the airframe beneath the skin is original

FURTHER INFORMATION

AirCorps Aviation is currently working on restorations of a P-51C and a war veteran ‘razorback’ P-47D-23. More about those projects can be found at the AirCorps website, www.projects.aircorpsaviation.com, or its Facebook page, www.facebook.com/aircorpsaviation.

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and flew over Germany and Belgium in 1945. Provenance is important in a war veteran because paperwork was sometimes sketchy for warbird transactions from the ’50s to the ’70s. There are always those who will dispute the real identity, so it was important to compare serialised parts to a list made up of observed serial and part numbers. The list was developed through long hours of examination of NAA engineering drawings and made into a spreadsheet. That way, parts can be checked to see if they were factoryinstalled or put on later from another P-51 or replacement.

v Even the grease pencil marks left inside the airframe by factory workers in 1944 were preserved. In the case of a replaced part, an overlay was made of the original and used to duplicate it on the new piece. Because 44-63675 was mostly bare metal, the mill-run metal finish and fasteners were very important to its final appearance. Research showed that bare metal Mustangs were rolled out with the Alclad logo visible not

only inside the aircraft but on the outside skin in places. In service, the external logo quickly wore off, but the restoration philosophy dictated that it should be there if AirCorps wanted to look like a factory-fresh Mustang. The modern logo was stripped from the stock used for replacement skins and the 1944 Alclad emblem reproduced and applied. Careful attention to how North American-produced Mustangs revealed other small details that set this restoration apart from previous aircraft. Among those are rivets of three distinct hues. They came from different suppliers. The pattern of colour was random, so the rivets were put on randomly, as they probably were when pulled from rivet bins on the production line. Authentic, too, are the dull acid-washed areas on the outer skin in areas where spot-welding had been done. Forties-era wiring was duplicated, WW2 tube radios refurbished and made functional, and innumerable other details attended to in the restoration. No wonder AirCorps Aviation feels that Sierra Sue II is one of the most accurately-restored P-51s in existence.