Flying Wings and Things

I used to think that we copied the idea for the flying wing from German WWII research, but I was off by several decades.

Then I realized that Jack Northrop was working on flying wings back in the 1930s, but he didn’t originate the idea either.

The concept is much older, going all the way back to 1910 when Hugo Junkers patented the idea of an all-wing aircraft. Turns out it actually was the Germans, just a lot earlier than I ever imagined.

Why build a flying wing? I’m not an aeronautical engineer, but the general idea is “more bang for the buck”. In a flying wing design, most of the aircraft’s structure is devoted to actually producing lift. There’s less dead weight to carry around. Because there’s less “stuff” like vertical fins and horizontal stabilizers sticking out into the slipstream, drag is minimized and internal volume is maximized.

Sounds great! So why aren’t we riding around in flying-wing airliners today? As usual the devil’s in the details.

I’ve frequently pointed out that what looks like copying is more likely a case of parallel development. The Americans, French, British, Germans and Russians all experimented with flying wings at various times. Air molecules in Germany work just like air molecules do here.

Russian designer Boris Ivanovich Cheranovsky experimented with flying wings as far back as the 1920s. Starting with gliders he went on to build several powered flying wing test aircraft.

One of Cheranovsky’s prototypes showing its oddly shaped wing. The BICh-7 prototype.

There’s not a lot of information out there about Cheranovsky, at least not in English. He designed roughly 30 gliders and powered aircraft over the years but I don’t know if any were ever built in large (or even small) numbers.

The proposed BICh-26 was arguably more of a tailless delta than a flying wing.

His last project was a Mach 1.7 flying wing fighter when his failing health put a stop to development in 1948.

A French designer Jean Charpentier built a prototype tri-motor flying wing in the 1930s. On its first takeoff attempt it flipped over on its back and was destroyed.

The C1 didn’t survive its first takeoff attempt. Photos are understandably rare.

Charpentier worked on several other designs but none were ever built. Things in France got kind of “interesting” around 1940 and Charpentier dropped off the radar. I’m not sure what happened to him.

In 1930s Germany, the Horten brothers built several successful flying wing sailplanes.

One of Horton’s all-wing sailplanes.

Fast forward to 1944 and we find Horten working on a jet powered flying wing, the Ho 229. Three prototypes were constructed. The second prototype reportedly outperformed the famous Me 262 in mock combat. Unfortunately the third prototype and its test pilot were lost due to an engine fire and crash.

The contract to build the new aircraft was awarded to Gotha, which is why it’s sometimes referred to as the Go 229. Fans of WWII flight simulators have probably seen the Go 229 in a “what if 1946?” scenario.

Part of the remaining Ho 229 prototype

The third prototype was taken to the United States. Today it resides at the Smithsonian’s Udvar-Hazy Center, where it awaits restoration.

The Ho 229’s story doesn’t end there, however. In 2008 Northrop-Grumman built a full scale replica of the Ho 229 as part of a television documentary. The replica’s radar cross section was tested and found to be roughly 40% of contemporary WWII fighters. While that sounds pretty impressive, it means that an Ho 229 would be detected 80 miles away by contemporary radars versus 100 miles for something like a Bf-109. Combined with its high speed, however, that would have greatly shortened the amount of warning time and made interception difficult. Stealth has never meant “invisible” just “harder to see”.

Flying wing designs inherently have a lower radar cross section because there’s not as much “stuff” to reflect radar waves.

After the war, Reimar Horten claimed that they mixed charcoal dust with the wood glue to absorb electromagnetic energy. Oddly enough he never mentioned this to anyone during the war.

Depending on who you believe this was either the world’s first purpose-built stealth fighter or the design was purely driven by aerodynamics. Either way it was definitely ahead of its time. We weren’t that far from the biplane era when this thing was built.

A full scale replica of the very futuristic looking Ho 229.

Horten also proposed a large flying wing bomber powered by six turbojets as part of Hitler’s Amerikabomber project. The name should give you a pretty good idea what it was for. Fortunately it never left the drawing board.

Fortunately we never had to deal with the “Amerikabomber”

The Germans, of course, weren’t the only ones working on a transatlantic bomber in the 1940s. In the early days of WWII, the survival of Great Britain was by no means assured. The US Army Air Corps felt the need for a bomber that could reach Europe from the United States in the event that Britain fell.

The original specification was for an aircraft that could carry 10,000 pounds of bombs on a 10,000 mile round trip at an altitude of 45,000 feet. That was a pretty tall order in 1941. For comparison, a B-17 could carry 6000 pounds of bombs a mere 1,700 miles.

Northrop thought that a flying wing would be the way to go. By minimizing drag and any structure that isn’t contributing to lift it would be much more efficient than a conventional design.

The original N-1M prototype gave the wingtips a sharp anhedral for yaw stability.

It’s one thing to make an all-wing airplane fly. Getting it to fly where you want it to is a bit more challenging. Today of course it’s no problem because we have computerized flight controls. With the right software you could probably make a John Deere tractor fly these days.

The Northrop N9-M. I so want this thing.

In the 30s and 40s it was a bit more tricky. Pitch and roll on a flying wing are normally accomplished through use of “elevons”. Elevons can move together to act as elevators or opposite each other to act as ailerons. Getting them to do both at the same time requires a fairly complex mechanism.

Yaw control is also tricky. Most designs seemed to use a set of “split flaps” near the wingtips. Opening one set would create drag on that wingtip and yaw the aircraft to that side. Now if you’re constantly having to do that because of yaw instability, that’s going to hurt your performance and negate some of the advantages of the all-wing design.

You can see the split flaps open on the right wingtip.

Northrop built four one-third scale test aircraft designated N-9M. The first N-9M (and its pilot) were lost while attempting to recover from a spin. The second and third were ultimately scrapped but the fourth and final N-9M was restored and flies to this day.

Northrop’s proposed bomber, the XB-35 was an extremely ambitious design for the 1940s. it used the same Pratt & Whitney R-4360 engines that would go on to power the Convair B-36. The engines were arranged in a pusher configuration, driving contra-rotating propellers.

The XB-35 prototype with contra-rotating propellers.

This was a lot of new technology in one aircraft and the untested engine/propeller combination produced unacceptable vibration. Switching to standard propellers solved the vibration problem but hurt performance.

Here you see the propellers have been switched to a conventional type.

The XB-35 first flew in 1946, too late for WWII. The first YB-35 prototype flew in 1948 and was ultimately scrapped in 1949.

The odd cockpit setup had the pilot sitting up under a fighter-type canopy with the copilot sitting down inside the wing.

I wonder if the B-35 would have suffered the same problems with carburetor icing and engine fires that plagued the B-36. Both used the same engines in a pusher configuration, so I think it’s a possibility.

The propeller issues were finally solved by fitting the aircraft with jet engines as the YB-49. With jets the aircraft easily met all performance requirements except for range. This was a bit of a problem since the Air Force at that time really wanted something that could reach the Soviet Union. Something about a Cold War I think.

The jet powered YB-49 in formation with a B-47.

One of the YB-49 prototypes was lost when it broke up in flight during stall tests. By some reports copilot Glen Edwards over stressed the aircraft. Pilots Forbes and Edwards both had Air Force bases named after them.

The switch to jets added small vertical fins for yaw stability.

The YB-49 overall performed well but did have some stability issues. As you might imagine, all of the problems inherent with a swept-wing aircraft are magnified when the aircraft is all wing. Dutch roll was an issue for the YB-49. Reportedly it needed a very lengthy bomb run to get “settled down” enough. Even fitting an autopilot with a yaw-damper may or may not have solved the problem sufficiently to allow for accurate bombing. It depends on who you ask.

Here’s where things get a little fuzzy.

If you’re a fan of conspiracy theories, the fix was already in for Convair and the B-36.

I do get the impression that the Air Force never was fully committed to the B-35/B-49. At one point they said they would only purchase the aircraft if it could carry the MK3 “Fat Man” atomic bomb. The Flying Wing carried its 10,000 pound bomb load distributed across eight small bomb bays. Accommodating a single large bomb like the MK3 would have been a problem. The Air Force also refused to allow the plane to be redesigned so that it could carry the MK3. Sounds like a Catch-22 to me.

From head on the YB-49 looks more like a UFO than an airplane.

Jack Northrop claimed that then Secretary of the Air Force Stuart Symington wanted him to agree to a merger with Convair and cancelled the B-35/B-49 when he refused. Symington did later go on to become president of Convair so who knows?

The last prototype, the YRB-49, oddly had two engines slung under the wing on pods.

Ultimately the B-35 and B-49 projects were discontinued and all prototypes and unfinished production models were ordered scrapped.

The B-36 also had its share of teething problems but the flying wing may have seemed just a bit too far ahead of its time. To the typical Air Force general of the day the B-36 at least looked like a bomber.

Today the YB-49 remains one of the great “what if” questions of aviation.

Northrop also built a prototype flying wing fighter. This was the XP-79. This highly ambitious project was originally going to be powered by liquid-fuel rockets and had the pilot lying prone instead of sitting. Paging Mister Coyote, Mister Wile E. Coyote…..

The XP-79 prototype.

Difficulties with the early rocket engines caused Northrop to switch to jet engines. Those weird looking intakes on the wingtips apparently used a bellows mechanism to boost the ailerons.

The XP-79 departed controlled flight during its first test. The test pilot was killed while trying to bail out. The project was cancelled immediately.

So there you have it. In the late 1940s Northrop produced some really interesting designs that were either kneecapped by political skullduggery or were just too far ahead of their time to work properly. Take your pick.

The British experimented with a jet powered flying wing in the late 1940s. Two flying prototypes of the Armstrong Whitworth A.W.52 were built.

The A.W.52 Prototype

One was lost after it encountered violent pitch oscillation at high speed. Fortunately it was fitted with the then-new Martin Baker Mk. 1 ejection seat. The remaining prototype was flown until 1954 but the project never went beyond the test stage.

It seems that the US and British largely abandoned the concept of flying wings in the early 1950s. I think one reason was the push for ever greater speed in the 1950s and 1960s. If you want your flying wing to actually carry anything, like people for instance, it has to be fairly thick. A thick wing doesn’t lend itself to supersonic flight. Between that and the stability issues I can see why the idea got put on the back burner in the 1950s.

Fast forward to 1980 and an elderly an very ill Jack Northrop was allowed to visit a highly classified section of Northrop Corporation. There he was shown a model of what was then called the Advanced Technology Bomber. Today we know it as the B-2 Spirit.

Jack was on his last legs at that time, he would die ten months later. Too ill to speak, he reportedly wrote on a notepad: "Now I know why God has kept me alive for 25 years".

The B-2 was perhaps Jack Northrop’s final vindication.

In recent years, NASA and Boeing have studied the concept of a “blended wing”, which is sort of halfway between a flying wing and a conventional aircraft.  Two small-scale, unmanned versions of the X-48 were built and flown as proof of concept. So far that’s as far as it’s gone.

The X-48B test vehicle. It looks big in the picture but the wingspan is actually 20 feet.

I don’t know if we’ll ever see a flying wing airliner for a couple of reasons.

Artist conception of a blended-wing airliner. If there is ever a Boeing 797 I doubt it will look like this.

The current infrastructure of gates and jet-ways would have to be reconfigured for the new designs. Passenger safety might be a problem as well. Passengers would be sitting in something that looked more like a movie theater than a tube. Evacuating them all in a timely manner might be a problem.

These may not be insurmountable problems, but the airlines would have to see a clear business case for spending the money.