Sierra Sue II

Sierra Sue II

Not many warbird enthusiasts hang on to one Mustang for 34 years, but Dr. Roger Christgau did with AAF 44-63675, Sierra Sue II. He thoroughly enjoyed flying her, especially in the Midwestern air show circuit. She was frequently seen in the skies over Eden Prairie and Austin, Minnesota, during those years. Doc, as he was known to the aviation community, loved to fly his P-51 hard and was well-known for wringing her out.

Anyone interested in aviation loves to see a Mustang in the air, and the folks in Austin are no exception. So that’s why, 26

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when the time came for Doc to sell Sierra Sue II, more than 150 people came out to the Austin airport to send her off in style.

The celebration was held on August 17, 2011. That wasn’t long after Sue’s current owner, Paul Ehlen, finalized the deal for 44-63675 as he, Doc, and Erik Hokuf of AirCorps Aviation waited in line at the driveup window of an Austin Dairy Queen on July 1!

One of his close friends, Reg Urschler, wrote this note for Sierra Sue II’s send-off celebration right after Doc sold her: “Please pass to Roger our warmest re-

gards and appreciation for being the best possible wingman a lead could ever want. Awesome ‘hands’ I would pit him against any fighter pilot.”

Besides having great memories of flying with Doc, Paul had been trying to purchase Sierra Sue II for five years because she is a World War II vet and has a great story to preserve.

That story began in Inglewood, California, two days after Thanksgiving on November 25, 1944. On that day, P-51D20-NA, ship number 516, construction number 122-31401, rolled off the North American

Minnesota Mustang, National Treasure

by Chuck Cravens

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Aviation assembly line. She was delivered to the AAF on the 27th and given the USAAF serial number 44-63675.

The AAF assigned her serial number 44-63675. Mustang

44-63675 was shipped overseas from Newark, New Jersey, on January 29, 1945. Her eventual destination was Advanced Landing Ground Y-32 O phoven, near Zwar tberg ,

Belgium. She arrived the first week of April 1945.

At the time, the 402nd was a P-38 outfit, but in March of 1945 it was re-equipped with Mustangs. www.warbirds-eaa.org 2 7

Mustang 44-63675 was assigned to 1st Lt. Robert Bohna of the 402nd Squadron, 370th Fighter Wing of the 9th Air Force on April 11, 1945. A few days earlier, Robert had sustained ground-fire damage, and the first Sierra Sue had to be written off after the ensuing belly landing. The 402nd, like all of the 9th Air Force units, was tasked with supporting the ground troops and was constantly exposed to the ground fire that had damaged the first Sierra Sue. Robert H. Bohna was born in Ukiah, California, on February 12, 1924. He grew up on the family cattle ranch near Raymond, California.

The story of the name Sierra Sue is worth relating. As John Christgau’s fine book Sierra Sue II, The Story of a P-51 Mustang explains, Bob Bohna had “taken special notice of Suzy Lang, the statuesque

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Suzanne Lang.

brunette a year ahead of him in geometry class.”

In an e-mail, Robert Bohna’s niece Diane told me, “As far as the gal Sierra Sue, I believe he had a major crush on her, and she was proper, shy, and nonreceptive to his love. Somewhere in the midst WWII began, and he was off to war with only a memory to hold onto.”

An interesting postscript to the story is that Suzy Lang, the girl from high school, would marry a B-17 pilot a year later. Her husband, Earl Holcomb, flew 18 combat missions with the 15th Air Force, 97th Bombardment Group, 414th Bombardment Squadron. His B-17 was named Croix de Suzanne after his wife, Suzy, so Suzanne Lang had the distinction of inspiring the nose art of two combat warplanes! One has to wonder how many women could

Suzanne Lang and Earl Holcomb wedding photo.

COURTESY SUSAN HEYWARD

COURTESY SUSAN HEYWARD

COURTESY SUSIE HICKMAN

Robert Bohna, 1945.

make that claim.

Robert wasted no time in personalizing his new P-51. Two different ground crew airmen were involved in the nose art. The lettering on the airplane was done in blue and red with white highlighting around each letter. Also added was a picture of a woman in a cowboy hat. While the lettering was beautifully done by the squadron’s best artist, the woman’s picture was crudely rendered by comparison. The artist who did the lettering wasn’t available for the painting representing Suzy Lang. A brown bar covered the breasts of the completed figure, which was very odd considering the popularity and of nude nose art at the time.

Two theories have been proposed to explain this myster y.

One version is that Lt. Bohna’s commanding officer objected to

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the bare-breasted portrayal of the woman on Sierra Sue II. But several P-51s in the 402nd had topless nose art, making that explanation doubtful. It’s more likely that Lt. Bohna had it changed himself. That makes sense considering that it wasn’t just any woman on the side of Sierra Sue II, but someone Robert had feelings for. He probably was uncomfortable with a nude representation of the girl he loved.

Lt . Bohna f lew this P-51D20-NA until the end of World War II. She flew her last combat mission on April 25, 1945, a B-17 escort mission on the last day that Flying Fortresses bombed Germany. They encountered three Me 262s. Bohna spotted them first.

John Christgau relates the story as Bob told it to him: “He spotted an Me 262 far off. Without breaking radio 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 dis-

tant 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 rush, even if the bullets went only halfway to the jet.”

After that mission, the war was effectively over for the 370th and for 1st Lt. Robert Bohna.

The brevity of her combat career is a big part of the reason that Sierra Sue II survives. She is one of about 20 to 25 flyable P-51Ds with documented WWII combat time.

With the war ended in the European theater of operations, an order went out in early June that all Mustangs with fewer than 200 hours were to be grounded. The grounded airframes were ferried out to Furth, Germany, for storage on June 19 and 20, 1945.

The reason for the order was probably to preser ve low-time fighters for later use in the Pacific theater of operations.

With the end of the war in the

Pacific eliminating that possibility, Sue sat idly, exposed to the elements, along with hundreds of other Mustangs. Many of them were brand-new, unused airplanes.

Because she wasn’t a new Mustang, almost three years passed before the Swedish Royal Air Force purchased Sierra Sue II. Now designated as a J26 with the Swedish serial number Fv26152, Sue was named Gul Kalle (yellow K) and flown by the 3rd Squadron of the Fighter Wing F4. Later she was transferred to F8 and repainted as Kleopatra, Gron Kalle (green K). In all, 44-63675 amassed 878 flight hours in Swedish service.

Her next owner was the Nicaraguan air force. She flew with the Fuerza Aérea de Nicaragua from 1954 to 1961. After that she was parked in front of the officers club at Las 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 www.warbirds-eaa.org 2 9

LOU DE PROPIS

Grease pencil marks from 1944 inside the wing.

Race 19, first flight day.

That brings us back to where this story began. Doc was the buyer, and the bill of sale was dated March 18, 1977. Thus began his 34-year love affair with Sierra Sue II. Bought an Air Force, but 44-63675 wasn’t one of the 26 P-51s taken out of Nicaragua at that time.

I was lucky enough to meet Will Martin and share a book-signing table with him and his daughter Suzanne at the Warbirds’ bookstore during AirVenture 2015. Will told me that 44-63675 had originally been part of his deal, but that the Nicaraguans switched her for a P-51 in much poorer condition. He suspected they would sell her for a higher price than the one he had negotiated.

In 1970, Californian Dave Allender wanted another Mustang.

An Alaskan P-51 pilot had spotted Sierra Sue II in Managua and informed Dave of the sighting. He found her in the Las Mercedes Officers Club compound. Dave then commenced negotiations that were almost as complicated as those Will Martin had gone through seven years earlier.

He took possession of 44-63675 in 1971. The bill of sale records the transfer from Col. Orlando Villalta, acting as agent for the Nicaraguan air force (FAN or Fuerza Aérea Ni30

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caragua), to David Allender Jr. of San Mateo, California, and is dated July 30, 1971.

Dave was active in air racing, but racing wasn’t the first objective for 44-63675. Once he got her back to Hayward, California, Dave and a group of supporters began modifications to make an attempt on the world piston-powered, closedcourse speed record. All the original parts were saved.

To get the Mustang up to nearly 500 mph at low altitude, extensive modifications were necessary. The wing extensions, or outer 3 feet of the wings, were unbolted at the existing spar joint and removed. One foot was also taken off the stabilizer. The angle of incidence of the wing was reduced, and the wing’s leading edge was fiberglassed to smooth the surface and reduce drag. A fiberglass Hoerner wingtip was also added. The turtledeck was straightened and a tiny smoked Plexiglas bubble canopy was fitted.

Naturally the powerplant was of primary importance to a record attempt. Dave picked well-known

hydro and air-racing mechanic Jack Cochrane to build a hybrid racing powerplant from Dave’s own stock of Rolls-Royce parts and engine blocks. Using a commercial airline 724 block and heads, the best and strongest parts of several RollsRoyce engines were machined to fit and produce a powerplant capable of producing 3,000 hp. A two-stage, two-speed supercharger from an F-82 was fitted to increase available boost.

In the end, after five years of work, lots of money, and several unsatisfactory test hops, Dave decided to move on. He returned Sierra Sue II to stock configuration other than retaining her red, orange, and white paint scheme, and put her up for sale.

That brings us back to where this story began. Doc was the buyer, and the bill of sale was dated March 18, 1977. Thus began his 34-year love affair with Sierra Sue II. When Paul Ehlen finally convinced Doc to sell, he had two major goals: first, to preserve the airplane as close to her original condition as he could, and, second, to tell her story. For that he continued the Minnesota legacy and entrusted Erik Hokuf and his partners at AirCorps Aviation to restore her. Every rivet was drilled out, and each part examined carefully in line with the preservation goal.

Roush Aviation did the engine work. The company provided a

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certificated rebuild with a few changes to improve reliability and durability.

Provenance is important in a war veteran because, from the ’50s through the ’70s, paperwork was sometimes sketchy for warbird transactions and returns to the United States. There are always those who will dispute the real identity, so it was important to compare serialized parts to a list 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 could be checked to see if they were factory-installed, were put on later from another P-51, or were new replacement parts.

T he goal of the restoration was to preserve or repair all possible original parts, even though that might prove more costly than making or buying a new part. Erik Hokuf estimated that 90 percent of the original airframe under the skins has been preserved.

Even the grease pencil marks left inside the airframe by factory

workers in 1944 were preserved.

W hen a replacement par t was used, an overlay was made of the original and used to duplicate it on the new piece.

Another detail that took this restoration to an amazing level of authenticity is the aircraft’s accurately re-created wiring. The wire used at Inglewood was insulated with black rubber and wound with cotton string. It was then lacquered and a logo was applied. To be as true as possible to 1944, Allied Wire & Cable of Pewaukee, Wisconsin, custom made wire with black silicon insulation. Ordinary rubber insulation is no longer allowed according to FAA specifications. Narragansett Reproductions of Wood River Junction, Rhode Island, then wrapped the wire with cotton string like the original stuff.

Eric Trueblood, one of the partners at AirCor ps Aviation, researched the logo right down to its original font. He found a period Kingsley wire-stamping machine with several type cases containing different sizes of the correct type.

All of the ribs and other parts

were dipped in primer at the factory rather than sprayed, and there are streaks in the finish just as there originally were. When parts had originally been sprayed in ’45, the order it was done in created areas of uneven paint or ghosting where the spray was blocked. By following that sequence, this effect was duplicated.

The fittings for the plumbing are original-period AC fittings rather than the current standard AN fittings found in most restored Mustangs.

Working equipment like the ’40s tube radios, the K-9 gun sight, the fuselage fuel tank, and gun cameras mark her as true to her factory configuration.

Sierra Sue II wasn’t meant to be a polished, mirror-finished showplane; rather, she was intended to show mill-finished skins with the inevitable scratches and the dull areas where the factory used an acid wash. Even the 1944 Alclad logo on the aluminum pieces was duplicated. It weathered off pretty rapidly during the war but would have shown up in places on a new www.warbirds-eaa.org 3 1

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Mustang for a time after delivery.

Unlike many other restored aircraft, Sierra Sue II isn’t painted to represent another Mustang; she has the precise color scheme and squadron markings she wore in Belgium and Germany during the war. Paint available to the crews in the ’40s was used, even though modern paints are more durable.

Accurately painting the nose art on any combat veteran presents a number of challenges. Most warbirds from the era, including Sierra Sue II, were never photographed in color during the war.

Of course, paint colors must be duplicated. Military specifications and available color samples usually make the process fairly straightforward for any paint applied by North American. The paint applied in the field, call sign letters, squadron identification, and any nose art are much more difficult to match with certainty. The reason is that no particular color standard was required for markings applied at the squadron level, and even British paint was sometimes applied in the field.

Later in the war, at the time that Sierra Sue II was given her squadron identity paint, it was most likely that AAF standard colors would have been applied. Paint transported to the European mainland would have come from U.S. stock.

With all those issues settled, Kevin Wisniewski painted Sierra Sue II’s nose art the week after her September 17, 2014, test flight.

Kevin, who goes by “Max” most of the time, is a retired firefighter and WWII re-enactor with a lifetime passion for WWII history.

He has always been particularly interested in artist’s renderings on aircraft and crew jackets. Max has been re-creating this style for decades, always striving to remain true to the techniques of the period.

Max is a talented artist, so accurately reproducing the crudely done girl on the side of the aircraft kind of went against his standards.

He didn’t want people to think he

Kevin “Max” Wisniewski.

would have chosen to draw her this way. We intend always to display Sierra Sue II with an enlarged 1945 photo of how she looked in the war so that event attendees will understand that the portrait was rendered that way for the sake of historical accuracy.

The first step in re-creating the nose art is to collect as much information as possible. Interviews of squadron pilots or crew members about colors and the process used for creating nose art in their squadron provide the best information. Sometimes those veterans can provide photos or scans of photos that are a great help. Shots of the aircraft in various stages as it was being painted are priceless, especially if they’re high-resolution.

Pictures of other aircraft from the same squadron can be very helpful as well. Jay Jones generously shared many good photographs he had obtained while writing his book on the 370th Fighter Group.

Knowing what AAF colors were likely to be on hand helps because it makes sense that the crewmen would use what was easily available.

Once the information is gathered and organized, comparisons of the tone of markings on the black-and-white photos can begin.

Colors that are known as a result

of research can be used. Technical drawings specify colors for insignia, anti-glare panels, and other factory markings. Prop blades on all Mustangs were black with yellow tips. Knowing these colors is a great help.

The painter can examine as many photos as are available and compare the unknown hues to the known ones.

The few color photos of 9th Air Force Mustangs that don’t have the entire fin and rudder painted another color show black tail lettering. If something looks as dark as the tail lettering, it is probably black. As the color tone varies away from black, it can be compared to any other known color and then a decision can be made.

The first picture below shows Robert Bohna and Sierra Sue II with nose art that hasn’t been completed.

The second picture has to be from later in the process because it shows the completed nose art. You can see highlighting on the letters and a lightning flash above them.

These two photos were instrumental in deciding on the colors. We knew from recollections of squadron members that the lettering was blue and red, and we had always assumed that what look like highlightshaped spaces were bare aluminum.

When the photos were blown up and intently examined, we could tell that those spaces were the same tone as the aluminum skin on the first photo but clearly didn’t match the aluminum on the second photo.

It would make sense that the wartime painter put on the red and blue at the same time and left space between them so they didn’t mix and make a mess. After that dried, he would have returned and added the white highlight, which could only have been done after the other colors had dried.

Several test letters were painted on bare aluminum scrap. Then they were photographed in black and white so they could be compared to the final highlighted letters on the second picture. The best match was accomplished when white was used as a highlight, so that was how the lettering was painted.

The girl on the side was another challenge. On some pictures the bar across her chest appears black, but in the better pictures it looks distinctly lighter than the crew lettering. The bottom of the bar appears to be a series of paint runs until the pictures are greatly enlarged, and then it looks more like fringe on a dress.

It is overly wide, but it’s possible that Robert asked for the 7L family cattle brand to be added, and it was extended to accommodate that request. By comparing colors test-photographed in black and white it was determined that the bar was brown.

The final decision was to paint the bar as a fringed dress top. With the information available, that seemed to be the best interpretation.

Decisions were made in the same way for hair color, the lightning flash color, and any other hue that showed up on Sierra Sue II in the 1945 photographs.

AirVenture 2015 brought people involved with the story of Sierra Sue II together in a way no other event could have. During the week, five members of the Bohna family, including Robert’s sister Susie Hickman, flew to Oshkosh, saw Sierra Sue II, and spent time with her owner, Paul Ehlen, and the AirCorps crew. Also joining Sierra Sue II in Oshkosh was Susan Heyward, the daughter of Suzie Lang, who inspired the nose art. All of them really enjoyed the experience and were able to sit in the cockpit of the actual Mustang Robert Bohna flew in Belgium and Germany in 1945.

Sierra Sue II flew during the week, as did most of the contenders for World War II Grand Champion. In the end, Sue received the Reserve Grand Champion Warbird award. It was great to see that happen.

During the awards ceremony, AirVenture officials said the competition featured perhaps the closest judging and the highest-quality top three entrants in recent memory.

A much more detailed and technical account of Sierra Sue II’s history and restoration can be found in my book Combat Vet P-51, The History of Sierra Sue II, World War II Survivor. It is available at AirCorpsAviation.com.

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