The People & Aircraft of Wings of The North Museum

by Chuck Cravens
Published in Midwest Flyer – August/September 2018 issue

There is a historical jewel located at Flying Cloud Airport in Eden Prairie, Minnesota. That gem is the “Wings of the North Museum,” which is dedicated to presenting and preserving aviation history. To accomplish this mission, organizers and volunteers host air displays, symposiums, school presentations, and other programs.

The Wings of the North Museum is a non-profit 501(c) (3) corporation, formed in 1998, and recently moved to its current facility near Flying Cloud’s air traffic control tower at 10100 Flying Cloud Drive. The museum features exhibits and displays that highlight Minnesota’s contributions to aviation and honor the many pioneers that impacted Minnesota’s place in aviation history.

The heart of an air museum is always the aircraft, and Wings of the North exhibits a variety of warbirds, trainers, and liaison aircraft. The most historically significant aircraft in the museum’s collection is “Sierra Sue II,” a P-51D-20NA Mustang. The aircraft is restored to precisely the way it appeared in April 1944 when it flew from Y-32 advanced landing ground near Ophoven, Belgium.

Fewer than 200 P-51D Mustangs are still operational, and of these, fewer than 30 saw action in World War II. Sierra Sue II, a Mustang flown in combat during the final month of the war, is one of those Mustangs.

In April 1945, a month before Germany surrendered to Allied forces, 1st Lt. Robert Bohna of the United States Army Air Corps was assigned Sierra Sue II after a belly landing put his first P-51, “Sierra Sue,” out of commission. Bohna would fly Sierra Sue II on 12 missions during the remaining days of the war.

After the war ended, Sierra Sue II became one of over 100 Mustangs sold to Sweden. The Royal Swedish Air Force flew the aircraft for nearly a decade and then sold it, along with 25 other Mustangs, to Nicaragua in 1954. Nicaragua kept the planes in service until 1961. The remaining Nicaraguan P-51s were sold in 1963, except for Sierra Sue II.  She was kept on display at Las Mercedes Air Base near Managua.

Nearly a decade later, American pilot Dave Allender bought Sierra Sue II from the Nicaraguan government and brought it to California. Allender bought the Mustang as the basis for an attempt at the closed-course piston-powered airspeed record, making numerous modifications to the airframe and engine to attain greater speed. After 12 years on the ground, Sierra Sue II flew once again in September 1973.

In 1979, Dr. Roger “Doc” Christgau of Edina, Minnesota, bought Sierra Sue II and brought it to the airport nearest to his home, Flying Cloud. He owned and flew this aircraft for nearly the rest of his life.

Christgau joined the U.S. Air Force in 1952 and served in Korea, Argentina, and Okinawa. He was stationed at Nellis Air Force Base in Nevada as an air combat maneuvering (ACM) instructor in 1955. When Christgau left the Air Force, he studied medicine at the University of Minnesota. He moved to Edina in 1964 where he established a successful family practice. It wasn’t until 1965 that he purchased a T-34 and a T-6 and flew again, but his dream was to own a P-51 Mustang. That dream came true in 1979 when he bought Sierra Sue II.

Christgau owned Sierra Sue II for the next 30 years and flew it in airshows around the Midwest, quickly becoming well-known as a skilled aerobatic pilot.

Doc flew Sierra Sue II for the last time in 2005, and in 2011, the plane was sold to Paul Ehlen, who decided to restore the aircraft to its original stock condition. Ehlen enlisted AirCorps Aviation of Bemidji, Minnesota, to do the restoration. The purpose of this restoration was not to create a shiny, pristine Mustang, but to create a Mustang that looked as authentic as possible, down to the nuts and bolts. Details like period-correct cotton-wrapped wiring and acid-washed areas where spot welding was done at the factory brought this restoration to another level.

During World War II, the American war machine was turning out aircraft so fast that there wasn’t time to make sure everything looked perfect; this plane was restored to show that.

The level of authenticity put into Sierra Sue II’s restoration has led some to characterize it as the most accurately restored Mustang in the world.

AirCorps Aviation finished Sierra Sue II’s restoration in September 2014, but it was too late for Roger Christgau to see the completed project; Doc passed away on October 5, 2012.

The same year that the restoration was completed, Paul Ehlen placed the Mustang on permanent loan to the Wings of the North Museum, which flys the warbird in airshows and special events throughout the upper Midwest.

Sierra Sue II was named Reserve Grand Champion Warbird at EAA AirVenture 2015. More recently, the aircraft led the U.S. Air Force Heritage Flight Foundation Flyover of Superbowl LII on February 4, 2018, flown by renowned warbird pilot and air racer, Steve Hinton of Chino, Calif.

According to Cary Pao, general manager at the Wings of the North Museum, the museum has relied on AirCorps Aviation for over 7 years to restore and maintain Sierra Sue II.

“AirCorps’ excellent workmanship and cutting-edge restoration technology has played a vital part in keeping our World War II veteran in tip-top condition and authenticity, just as it was when it rolled off the North American assembly line in 1944,” said Pao. “We are proud to have AirCorps Aviation, led by general manager Erik Hokuf, as our long-term industry partner to showcase our flying aircraft and inspire our youth to be prepared for the technology challenges of the future.”

Over this past year, AirCorps has also completed an upgrade on the museum’s TBM Avenger airframe and restored it back to flying condition. Pao also mentioned ongoing projects: “Wings of the North projects, including an original BT-15 and AT-11 aircraft, will also be restored by AirCorps Aviation as we are able to raise funding.

“When complete, these aircraft will become part of exciting new ground and flight experiences for the community, with hands-on opportunities to taste what it was like to be a World War II pilot or navigator/bombardier training candidate using an authentic Norden Bombsight that was then state-of-the-art.

“Visitors will also see how technology has changed over the years since World War II, but that the fundamental skills and pioneering spirit of people are what drive our future. We plan to provide these experiences to inspire our youth.”

Besides Sierra Sue II, there are several other flying aircraft to see at the Wings of the North Museum:

An airplane that epitomizes Wings of the North’s mission to preserve Minnesota’s historical place in aviation is the “Bush” Stearman. Bureau Number 3347 is an NS2-1 Navy Stearman documented to have been flown by George H. W. Bush twice in the winter of 1943-44 at Wold Chamberlain Field. Flight training in an open cockpit biplane in Minnesota January weather had to be tough duty!

This Stearman was named “Best Stearman” at EAA AirVenture in 2015.

CR 528 is the third award-winning aircraft at on display at Wings of the North Museum. EAA Warbirds of America named the aircraft “Best T-6” at the EAA AirVenture in 2008.

Ongoing Projects:

On April 21, 2018, the Wings of the North Museum (WOTN) and the Minnesota Aviation Hall of Fame (MAHOF) held a ribbon-cutting ceremony to commemorate the new home of the MAHOF, featuring plaques of all inductees. Among this year’s inductees was Bob Jasperson, WOTN Museum Director.

Also, this year, the Wings of the North Museum launched the Pathfinders Showcase Series beginning in May with a Skies Over Vietnam event. The event was presented in partnership with Twin Cities Public Television and its Minnesota Remembers Vietnam Series. In June, an exclusive Girls Fly Boldly event was held featuring Maj. Heather Penney, who was one of two U.S. Air Force pilots ordered to take down United Flight 93 with their unarmed F-16 Falcons on September 11 2001. Nicole Mitchell, KSTP meteorologist and USAF Reserve “Hurricane Hunter,” was also a guest speaker.

While specific dates and times haven’t been determined, upcoming Pathfinders Showcase Series events include:

October: Featuring Woody Fountain (1st African American Pilot, Northwest Airlines).

November: Featuring Joe Kilpatrick (Proposed), Inventor of the Honeywell Ring Laser Gyro.

Details on these and other museum happenings are available at

If you would like to help Wings of the North Museum continue to make its mission a reality, the museum is accepting financial support, equipment donations (copy machines, office equipment, tools, and computers), and postage to aid operations. The museum is also seeking donations of aviation artifacts, such as flyable aircraft of any type, restoration project aircraft, aviation memorabilia (military aviation uniforms, wings, maps, and photographs), and hangar space.

Email Cary Pao at or call (952) 473-3066 for more information.

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