Monday, September 26, 2011

Odd Warbirds

I’m a bit of a history buff and one of my favorite topics is military aviation, especial the WWII era. Wars invariability lead to a massive acceleration in the development of technology, within compressed timeframes by necessity. Well-trimmed peacetime budgets are left in the dust as the race for survival takes over. The 1930’s designed aircraft the U.S. began WWII with were totally antiquated by the end of the war. In fact, the U.S. had let its military budget languish so much that most of our aircraft were pitifully outclassed when war broke out. The Brewster Buffalo is a great example of this. They were called Flying Barrels, or worse, Flying Coffins.

Germany had a number of superior aircraft when the initiated the conflict, especially in the realm of fighters. And the German innovative engineering and design never stopped throughout the war. The Allied forces were extremely fortunate that the bombing of Germany, however costly, was successful in disrupting production and manufacturing, otherwise the outcome could have been different. As it was, Germany got the first jet fighter into limited production and produced V-1 rockets (“Buzz bombs”) in numbers.

One brilliant German design that could have helped change the air war in their favor was the Dornier 335 “Pfeil” – “Arrow” – a very clever push-pull design. The Pfeil's performance was much better than other twin-engine designs due to its unique "push-pull" layout and the much lower drag of the in-line alignment of the two engines. The Luftwaffe was desperate to get the design into operational use, but delays in engine deliveries meant only a handful were delivered before the war ended.

There are many advantages to this design over the more traditional system of placing one engine on each wing, the most important being power from two engines with the frontal area (and thus drag) of a single-engine design, allowing for higher performance. It also keeps the weight of the twin powerplants near, or on, the aircraft centerline, increasing the roll rate compared to a traditional twin. In addition, a single engine failure does not lead to asymmetric thrust, and in normal flight there is no net torque so the plane is easy to handle. The choice of a full "four-surface" set of cruciform tail surfaces in the Do 335's design, allowed the ventral vertical fin–rudder assembly to project downwards from the extreme rear of the fuselage, in order to protect the rear propeller from an accidental ground strike on takeoff.

On 23 May 1944, Hitler, as part of the Jägernotprogramm directive, ordered maximum priority to be given to Do 335 production. The main production line was intended to be at Manzel, but a bombing raid in March destroyed the tooling and forced Dornier to set up a new line at Oberpfaffenhofen. The decision was made to  rapidly shut-down many other military aircraft development programs and use the production facilities for the Do 335.

Delivery commenced in January 1945. When the United States Army overran the Oberpfaffenhofen factory in late April 1945, only 11 Do 335 A-1 single-seat fighter-bombers and two Do 335 A-12 trainers had been completed.

French ace Pierre Clostermann claimed the first Allied combat encounter with a Pfeil in April 1945. In his book The Big Show he describes leading a flight of four Hawker Tempests over northern Germany, when he intercepted a lone Do 335 flying at maximum speed at treetop level. Detecting the British aircraft, the German pilot reversed course to evade. Despite the Tempest's considerable low altitude speed, the RAF fighters were not able to catch up or even get into firing position. In its single-seat version it was one of the fastest piston-engined fighters ever built, with a claimed top speed of around 475 mph.

Flying the Pfeil was an experience, thanks to its high performance and unusual configuration. While the performance provided an exhilarating ride for the pilot, the configuration prompted some doubts. His main concern was the ejection seat, the Do 335 being only the second production type to feature this. Before firing the seat, explosive bolts which held the upper vertical tail surface and rear propeller were fired to clear a way for the egressing pilot. Despite the ejection seat, he had to jettison the canopy manually.

Only one Do 335 survives today. It was captured by Allied forces at the plant on 22 April 1945. The aircraft was test flown from a grass runway at Oberwiesenfeld, near Munich, to Cherbourg, France while escorted by two P-51s. The Do 335 was easily able to out distance the escorting Mustangs and arrived at Cherbourg 45 minutes before the P-51s.

Brought to the U.S. for testing, it then sat in storage in Maryland until the 1970s when it was restored (for static display, not air worthy). Dornier’s 335 Arrow can be seen today in the Steven F. Udvar-Hazy Center of the National Air & Space Museum at Dulles Airport alongside other unique late-war German aircraft.

1 comment:

Ian from Australia said...

Terrific photos. Thanks a lot!