Was Hitler’s Ho 299 the First True Stealth Fighter?

 In China, Air, Germany, FVEY, France

Key point The plane never took over. However, it did acci­den­tal­ly stum­ble upon how a cer­tain shape can help reduce a plane’s radar sig­na­ture.

Northrop Grumman revealed this year it is devel­op­ing a second flying wing stealth bomber, the B‑21 Raider, to suc­ceed its B‑2 Spirit. However, it was a pair of German broth­ers in the ser­vice of Nazi Germany that devel­oped the first jet-pow­ered flying wing — which has been dubbed, debat­ably, “Hitler’s stealth fight­er.”

But max­i­miz­ing speed and range, not stealth, was the pri­ma­ry moti­va­tion behind the bat-shaped jet plane.

Walter Horten was an ace fight­er pilot in the German Luftwaffe, having scored seven kills flying as wing­man of the leg­endary Adolf Galland during the Battle of Britain. His broth­er Reimar was an air­plane design­er lack­ing a formal aero­nau­ti­cal edu­ca­tion. In their youth, the pair had designed a series of inno­v­a­tive tail-less manned glid­ers.

In 1943, Luftwaffe chief Herman Goering laid out the so-called 3×1000 spec­i­fi­ca­tion for a plane that could fly one thou­sand kilo­me­ters an hour car­ry­ing one thou­sand kilo­grams of bombs with fuel enough to travel one thou­sand kilo­me­ters and back — while still retain­ing a third of the fuel supply for use in combat. Such an air­plane could strike tar­gets in Britain while out­run­ning any fight­ers sent to inter­cept it.

Clearly, the new tur­bo­jet engines Germany had devel­oped would be required for an air­plane to attain such high speeds. But jet engines burned through their fuel very quick­ly, making raids on more dis­tant tar­gets impos­si­ble. The Horten broth­ers’ idea was to use a flying wing design — a tail-less plane so aero­dy­nam­i­cal­ly clean it gen­er­at­ed almost no drag at all. Such an air­frame would require less engine power to attain higher speeds, and there­fore con­sume less fuel.

Flying wing designs were not an entire­ly new idea and had been used before in both glid­ers and pow­ered air­craft. During World War II, Northrop devel­oped its own high-per­form­ing XB-35 flying wing bomber for the U.S. mil­i­tary, though it failed to enter mass pro­duc­tion. Despite the aero­dy­nam­ic advan­tages, the lack of a tail tended to make fly wing air­craft prone to uncon­trolled yaws and stalls.

The Horten broth­ers were given the go-ahead to pursue the con­cept in August 1943. They first built an unpow­ered glider known as the H.IX V1. The V1 had long, thin swept wings made of ply­wood in order to save weight. These “bell-shaped” wings com­pen­sat­ed for yawing prob­lem. Lacking a rudder or ailerons, the H.IX relied upon “elevons” (com­bi­na­tions of ailerons and ele­va­tors) and two sets of spoil­ers for con­trol. The elevons could be moved dif­fer­en­tial­ly to induce roll, or togeth­er in the same direc­tion to change pitch, while the spoil­ers were used to induce yaw.

Following suc­cess­ful tests of the V1 glider at Oranienberg on March 1944, the sub­se­quent V2 pro­to­type was mount­ed with two Jumo 004B tur­bo­jet engines nes­tled to either side of a cock­pit pod made of welded steel tubing. It also fea­tured a prim­i­tive ejec­tion seat and a drogue chute deployed while land­ing, while redesigned tri­cy­cle land­ing gear was installed to enable the plane to carry heav­ier loads.

The first test flight occurred on February 2, 1945. The manta-shaped jet exhib­it­ed smooth han­dling and good stall resis­tance. The pro­to­type even report­ed­ly beat an Me 262 jet fight­er, equipped with the same Jumo 004 engines, in a mock dog­fight.

But the test­ing process was cut short on February 18 when one of the V2’s jet engines caught fire and stopped mid-flight. Test pilot Erwin Ziller per­formed a number of turns and dives in an effort to restart the engine, before appar­ent­ly pass­ing out from the fumes and spi­ral­ing his plane into the ground, mor­tal­ly wound­ing him.

Regardless, Goering had already approved the pro­duc­tion of forty flying wings, to be under­tak­en by the Gotha com­pa­ny, which mostly pro­duced train­ers and mil­i­tary glid­ers during World War II. The pro­duc­tion planes were des­ig­nat­ed Ho 229s or Go 229s.

Because of the Ho 229’s great speed — it was believed the pro­duc­tion ver­sion would be able to attain 975 kilo­me­ter per hours — it was repur­posed to serve as a fight­er with a planned arma­ment of two heavy Mark 103 thirty-mil­lime­ter can­nons. Construction of four new pro­to­types — num­bered V3 throuh V6— was ini­ti­at­ed, two of which would have been two-seat night fight­ers.

However, the Ho 229 never made it off the ground. When American troops of VIII Corps rolled into the fac­to­ry at Friedrichroda, Germany in April 1945, they found just the cock­pit sec­tions of the pro­to­types in var­i­ous stages of devel­op­ment. A single pair of cor­re­spond­ing wings was found 75 miles away. The most com­plete of the four, the V3 pro­to­type, was shipped back to the United States for study along with the wings, and can today be seen under restora­tion at the Udvar-Hazy Center of the United States Air and Space Museum in Chantilly, Virginia.

The Hortens were reas­signed to draft spec­i­fi­ca­tions for a flying wing jet bomber with range enough to deliv­er an atom bomb to the east coast of the United States. Their result­ing schemat­ics for the Horten H.XVIII “Amerika Bomber” flying wing were never real­ized, except arguably in the film Captain America.

Was the Ho 229 a stealth fight­er?

One word you haven’t seen in this his­to­ry so far is “stealth” — and that’s because there isn’t any doc­u­men­ta­tion from the 1940s sup­port­ing the notion that the flying wing was intend­ed to be a stealth air­craft. And yet, the Hortens had stum­bled upon the fact that a flying wing design lends itself to the sort of reduced radar cross-sec­tion ideal for a stealth plane.

Reimer Horten moved to Argentina after the war, and in 1950 wrote an arti­cle for the Revista Nacional de Aeronautica argu­ing that wooden air­craft would absorb radar waves. Thirty years later, as the theory behind stealth air­craft became more widely known, Reimer wrote that he had inten­tion­al­ly sought to make the Horten flying wing into a stealth plane, claim­ing that he had even con­struct­ed the air­frame using a spe­cial radar absorbent mix­ture of carbon, saw­dust and wood glue with­out noti­fy­ing his supe­ri­ors. Two tests were under­tak­en to deter­mine the pres­ence of the carbon dust, one of which sup­port­ed his claim and the other that didn’t. In gen­er­al, his­to­ri­ans are skeptical that stealth was a design goal from the outset.

In 2008, Northrop Grumman teamed up with the National Geographic chan­nel to recon­struct a mockup of the Ho 229, which they tested for radar reflec­tion, and then pitted against a sim­u­la­tion of the British Chain Home radar net­work. Their find­ings were less than over­whelm­ing — the flying wings would have been detect­ed at a dis­tance 80 per­cent that of a stan­dard German Bf. 109 fight­er.

The Northrop testers stressed that com­bined with the Ho 229’s much greater speed, this modest improve­ment would have given defend­ing fight­ers too little time to react effec­tive­ly.

But of course, the flying wing’s main fea­ture was always sup­posed to be its speed, which could have exceed­ed the max­i­mum speed of the best Allied fight­ers of the time by as much as 33 per­cent. Detection time would not have mat­tered great­ly if it could outrun every­thing sent to inter­cept it. Furthermore, stealth would have had little use­ful­ness in the fight­er role the Ho 229 would actu­al­ly have assumed, as the Allied day­light fight­ers rang­ing over Germany did not ben­e­fit from radars of their own.

The Ho 229 might have been a for­mi­da­ble adver­sary over the skies of World War II, but in truth the plane was far from ready for mass pro­duc­tion by the war’s end. While it seems a stretch to claim that the Ho 229 was intend­ed to be a stealth air­craft, there’s little doubt that it pio­neered design fea­tures that con­tin­ue to see use in low-observ­able air­craft today.

Sébastien Roblin holds a Master’s Degree in Conflict Resolution from Georgetown University and served as a uni­ver­si­ty instruc­tor for the Peace Corps in China. He has also worked in edu­ca­tion, edit­ing, and refugee reset­tle­ment in France and the United States. He cur­rent­ly writes on secu­ri­ty and mil­i­tary his­to­ry for War Is Boring.

Image: Reuters

National Interest source|articles

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