This Date in Aviation History: December 12 - December 14

"ttyymmnn" (ttyymmnn) 12/14/2018 at 12:35 • Filed to: wingspan, planelopnik history, Planelopnik

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Welcome to This Date in Aviation History , getting of you caught up on milestones, important historical events and people in aviation from December 12 through December 14.

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The second of two X-29 experimental forward-swept wing aircraft flies over the California desert in 1990. Strips of cloth fitted to the fuselage and wings help visualize airflow over these surfaces. (NASA)

December 14, 1984 – The first flight of the Grumman X-29. Aside from a few notable experiments, the majority of aircraft up until the 1930s followed the example of the Wright Brothers’ 1903 flyer and utilized a straight wing, perpendicular to the fuselage. A straight wing allows for relatively simple construction, and provides good handling at lower speeds, particularly during landing. Some of the earliest experiments with swept wings, notably those built by Briton !!!error: Indecipherable SUB-paragraph formatting!!! , attempted to use a swept wing to create a tailless aircraft, or flying wing. Though other manufacturers took up the concept before WWII, the exigencies of wartime aircraft production meant that proven straight-wing designs took precedence over swept wings, at least in large volume production.

The idea that swept wings might be useful in supersonic flight was proposed in 1935 by German aerodynamicist Adolf Busemann. The swept wing has the benefit of producing less drag at transsonic and supersonic speeds, though no aircraft were available at the time that could fly at such speeds. Later in WWII, with the arrival of the operational jet engine, the Germans worked at the forefront of swept wing technology, with both experimental and operational swept wing aircraft. The !!!error: Indecipherable SUB-paragraph formatting!!! , the world’s first operational jet fighter, employed a wing that was swept by 18.5 degrees.

Junkers Ju 287, a prototype four-engine bomber with forward-swept wings. Only two were built, and it took its maiden flight in August 1944. (Author unknown)

But along with their work in swept wing aircraft, German scientists also worked on the concept of a forward-swept wing, along with others in Poland and the United States. Perhaps counterintuitively, the forward-swept wing has the same drag-reducing properties of a traditional swept wing, with the added benefit of improved stall characteristics, since the air that is swept along the wing concentrates at the wing root rather than the wing tip. Additionally, the spar box, which supports the wing, can be placed farther aft, opening up more space inside the fuselage. The Germans actually built a large bomber with forward-swept wings, the !!!error: Indecipherable SUB-paragraph formatting!!! , but they soon learned that the stresses placed on the wings and fuselage, particularly during high-speed turns, were too great for the materials of the day, and a phenomenon known as !!!error: Indecipherable SUB-paragraph formatting!!! threatened to tear the wings off the aircraft.

The HFB-320 Hansa Jet, a forward-swept wing business jet and the first production aircraft to be fitted with such wings. (Author unknown)

Experiments with the concept of forward swept wings continued after the war, and the design was utilized on the !!!error: Indecipherable SUB-paragraph formatting!!! , an otherwise traditional business jet with forward-swept wings. But the Hansa Jet was never designed to fly beyond the speed of sound, and the structural problems associated with aeroelastic flutter remained unsolved. What was needed was a material that was strong enough to handle the stresses of supersonic flight, while remaining light enough so as not to hinder the aircraft’s performance. By the 1980s, those materials were finally available in the form of carbon-fiber composites and graphite epoxy, and Grumman put both of to use in the construction of the X-29.

Both X-29 aircraft on Rogers Dry Lake in 1990. The characteristic long pointed nose of the F-5 Freedom Fighter, as well as the splayed main gear of the F-16, can be seen. (NASA)

In order to save money, the two X-29s were built using the nose and forward landing gear taken from a pair of !!!error: Indecipherable SUB-paragraph formatting!!! , and control actuators and main gear from the !!!error: Indecipherable SUB-paragraph formatting!!! . It was powered by a single General Electric F404 turbofan, the same engine found on the !!!error: Indecipherable SUB-paragraph formatting!!! . With its wing swept forward at more than 33 degrees, the X-29 was one of the most unstable aircraft ever built. Without constant corrections provided by the triple-redundant flight computer through its fly-by-wire controls, the X-29 would have been unflyable. But that instability also meant that the X-29 was extremely maneuverable, and inherent instability, or !!!error: Indecipherable SUB-paragraph formatting!!! , with computer assistance is a component of many current fighter aircraft.

The second X-29, 82-0049, flown by NASA test pilot Rogers Smith, demonstrates the high angle of attack possible with the X-29. A smoke generator in the nose helps visualize airflow over the front of the aircraft. Note also the rescue parachute mounted above the engine exhaust nozzle. (NASA)

When the X-29 took to the air, it was only the third jet-powered aircraft to fly with forward-swept wings. The two experimental aircraft made a total of 242 test flights over a seven-year program that ended in 1991. The second aircraft was fitted with a rescue parachute in case of an unrecoverable stall while carrying out flight tests that explored high angles of attack, and achieved as much as 45 degrees AOA, more than any contemporary fighter. The X-29 was also the first forward-swept wing aircraft to exceed Mach 1 in level flight. Though the test program did not demonstrate the overall reduction in drag thought possible, its use of pioneering construction materials and computerized flight control have had a far-reaching influence over subsequent aircraft design. Both X-29s have since been retired, and they are currently on display at the National Museum of the United States Air Force and the Armstrong Flight Research Center.

The first X-29, serial number 82-003, hangs in the Research and Development Gallery at the National Museum of the United States Air Force (Tim Shaffer)

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Short Takeoff

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(Pedro Aragăo )

December 12, 1985 – The crash of Arrow Air Flight 1285, a chartered !!!error: Indecipherable SUB-paragraph formatting!!! (N950JW) that was carrying eight crew members and 248 soldiers of the US Army !!!error: Indecipherable SUB-paragraph formatting!!! returning to Fort Campbell, Kentucky after serving in a peacekeeping mission in the Sinai Peninsula. On the final leg of the flight, the DC-8 crashed shortly after takeoff from Gander, Newfoundland, killing all on board. The investigation concluded that the crash was caused by the accumulation of ice on the wings, as well as incorrect weight calculations. However, some investigators dissented, saying that a fire or explosive device likely caused the crash. The accident remains the deadliest single peacetime loss of life in the history of the US Army and the worst crash on Canadian soil.

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(US Navy)

December 12, 1979 – The first flight of the Sikorsky SH-60B Seahawk, a navalized variant of the !!!error: Indecipherable SUB-paragraph formatting!!! utility helicopter originally developed for the US Army. Also known as the Sea Hawk, the SH-60B was developed to replace the !!!error: Indecipherable SUB-paragraph formatting!!! , and it shares 83% commonality with its Army predecessor, with the most significant structural difference being a hinged tail for on-deck storage. The Seahawk also differs by the addition of !!!error: Indecipherable SUB-paragraph formatting!!! main gear struts, the shifting forward of the tail wheel, and a more powerful engine. Able to operate from any air-capable ship, the Seahawk is designed for anti-submarine warfare, anti-surface warfare, naval special warfare, search and rescue, vertical replenishment, and medical evacuation. Further variants have replaced the !!!error: Indecipherable SUB-paragraph formatting!!! and !!!error: Indecipherable SUB-paragraph formatting!!! .

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December 12, 1951 – The first flight of the de Havilland Canada DHC-3 Otter. With the !!!error: Indecipherable SUB-paragraph formatting!!! , de Havilland Canada had built a reputation for rugged aircraft that were capable of taking off from short or unimproved airstrips, and the DHC-3 Otter was designed to be a larger and more powerful aircraft that could perform the same mission. Originally called the King Beaver, the DHC-3 is longer and heavier than the DHC-2, and can seat 10-11 passengers. Originally fitted with a !!!error: Indecipherable SUB-paragraph formatting!!!   !!!error: Indecipherable SUB-paragraph formatting!!! geared radial engine, some Otters have been upgraded with a turboprop engine and are known as the Turbo Otter. The Otter is capable of operating from land, from sea with floats, or from snow with skis, and 466 Otters were produced from 1951-1967.

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December 14, 1979 – The first flight of the EA-7 Edgley Optica, a light observation aircraft designed to be a low-cost alternative to helicopters. The unique design features a glazed bubble canopy set well forward which provides excellent visibility, a twin boom tail, and tricycle landing gear. The original Optica was powered by a !!!error: Indecipherable SUB-paragraph formatting!!! engine driving a ducted, fixed-pitch propeller, an arrangement that resulted in very quiet operation. Production of 22 aircraft was followed by numerous changes in Edgley’s ownership, and financial difficulties led to a halt in production. However, the transportation consulting and finance firm !!!error: Indecipherable SUB-paragraph formatting!!! is investigating the possibility of restarting production in 2018 or 2019.

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December 14, 1977 – The first flight of the Mil Mi-26, a heavy lift helicopter designed for civilian and military use and the largest and most powerful helicopter ever to enter production. Powered by two !!!error: Indecipherable SUB-paragraph formatting!!! turboshaft engines and fitted with an eight-bladed main rotor, the Mi-26 is capable of lifting 44,000 pounds and was designed to replace the !!!error: Indecipherable SUB-paragraph formatting!!! and !!!error: Indecipherable SUB-paragraph formatting!!! heavy-lift helicopters. The Mi-26’s main purpose is to move extremely heavy equipment between Russian military bases, such as armored personnel carriers and mobile ballistic missiles, with some payloads weighing as much as 29,000 pounds. A total of 316 Mi-26s have been built, and the helicopter remains in production.

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Connecting Flights

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If you enjoy these Aviation History posts, please let me know in the comments. And if you missed any of the past articles, you can find them all at !!!error: Indecipherable SUB-paragraph formatting!!! . You can also find more stories about aviation, aviators and airplane oddities at !!!error: Indecipherable SUB-paragraph formatting!!! .

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farscythe - makin da cawfee! > ttyymmnn 12/14/2018 at 12:45

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shoulda painted it yellow and black and called it the EA-7 edgle y wasp

(just my 2 cents)

also im a sucker for the x-29... always figured that’d evolve into the fighters of the future

any day now :p

user314 > farscythe - makin da cawfee! 12/14/2018 at 12:58

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Yeah, I wanted one of these in the worst way:

facw > ttyymmnn 12/14/2018 at 13:12

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Always liked seeing the X-29 mockup at Air and Space as kid (though it was downstairs then, looks like they removed it from the mall altogether in 2011 ) :

Didn’t get to see the real thing in Dayton, my visit was too time limited to view the on-base hangars (before the opened the 4th hangar)

facw > farscythe - makin da cawfee! 12/14/2018 at 13:15

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Grumman did suggest a possible forward swept design very early in what would become the ATF (F-22) project:

user314 > facw 12/14/2018 at 13:55

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Huh, not a lick of stealth/low observable in any of those designs, is there? Boeing’s looks like an X-31, interestingly enough. I love how Lockheed’s design is basically a YF-12 with retr actable canards

ttyymmnn > facw 12/14/2018 at 13:58

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The fourth hangar is jaw-dropping.

facw > user314 12/14/2018 at 14:09

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Yeah, you can see a bit of the YF-23 in Northrop’s designs, which could be stealthy, though also are tiny F-5 sized planes rather than anywhere near YF-23 sized. Beyond that , clearly whoever was running this program wasn’t too worried about stealth at that point. A lot of these look like they would have ended up as 4.5- gen designs like the Eurofighter/Rafale/Gripen had they continued to development. The diamond winged McDonnell model is interesting, you could sort of picture them getting to that by shifting the YF-17/Hornet wing all the way to the back, and adding canards, but it’s an unusual configuration, I wonder what the advantages would be, aside from looking cool.

facw > ttyymmnn 12/14/2018 at 14:10

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I can imagine, looked like they put a lot of cool stuff in there. 

Y2K996Cab > ttyymmnn 12/14/2018 at 14:18

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I think you have a typo in M i- 26 short take where you refer to the Mi- 12 main purpose. Do you mean Mi- 26 in that sente nce ?

user314 > facw 12/14/2018 at 14:24

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Oh God, Boeing’s swing-wing design is even worse than I thought:

Grumman’s FSW would have been sweet though:

ttyymmnn > facw 12/14/2018 at 14:43

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Valkyrie! Plus a lot of other X plane stuff from that era, which is my favorite. It was awesome seeing so many of the a/c I have written about.

ttyymmnn > Y2K996Cab 12/14/2018 at 14:43

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You are correct. Thanks!

wafflesnfalafel > ttyymmnn 12/14/2018 at 15:06

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W e were on one of those turboprop converted Otters up in Ketchikan last year. I was surprised how spry that thing was for a 50 yo air truck .

ttyymmnn > wafflesnfalafel 12/14/2018 at 15:28

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Alotta pull in that motor, I would suspect. As for the age, if it ain’t broke.....

f86sabre > ttyymmnn 12/14/2018 at 15:47

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One of my friends worked on X-29 design and flight test when she was a young engineer. You highlighted how it was assembled from various bits and pieces of other aircraft. She said the planes were pretty rough, but they were great fun to work with. 

user314 > ttyymmnn 12/14/2018 at 16:11

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I love how that looks for all the world like a model hung up on fishing line.

ttyymmnn > user314 12/14/2018 at 17:16

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It does. Here’s another shot I took. I thought about posting this one because it shows the wings and canard well. That’s the X-5 in the background. That whole 4th hangar is just amazing. 

user314 > facw 12/14/2018 at 17:22

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I’ve been there twice, once back in the early Nineties , which was cool, though I don’t remember much, and then again about a month after 9/11, so everything on the base itself was still on lock- down.

Getting back out to really take everything in is on my to-do list.

TheRealBicycleBuck > ttyymmnn 12/14/2018 at 18:17

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There are several good videos on the Optica. Somehow they popped up in my feed the other day and I fell down that rabbit hole. 

Look!NoEngine > ttyymmnn 12/17/2018 at 18:02

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Thanks for a great year of aviation.  I really look forward to reading your work every week.

ttyymmnn > Look!NoEngine 12/17/2018 at 18:06

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Thank you! And I’ve already got the installments (mostly) written through January 1. I’m trying to get vacation covered. Lots of people kvetch about Kinja, but the ability to write posts in the future is the only thing that makes this possible.

Thanks for reading!