Tag Archives: delta wing

Lippisch P 13a

August 16, 2023Weimar and Nazi Germany, WW2delta wing, Experimental, Luftwaffe, Nazi Germany, rocket, WW2Marko P.

Nazi Germany

Ramjet powered aircraft

None built

In the later stages of the Second World War, it was becoming apparent to both the Luftwaffe (English German Air Force) and the German Government that the Allied air forces were gaining air superiority. This realization saw them turn to new and fantastical ideas in a desperate attempt to turn the tide of the war. Some of these represented new improvements to existing designs, the introduction of the newly developed turbojet engine, and even more esoteric and experimental methods. In many cases, these were pure fantasies, unrealistic or desperate designs with no hope of success. Few of them reached any significant development, and among them were the works of Alexander Martin Lippisch. While Lippisch helped develop the Me 163, the first rocket-powered interceptor, his other work remained mostly theoretical. One such project was the unusual P 13a, ramjet-powered aircraft that was to use coal as its main fuel source. While some work was carried out late in the war and soon faced insurmountable technical problems, thus nothing came of the project.

Artistic presentation of how the P 13a may have looked. Source: Luftwaffe Secret Jets of the Third Reich

History

Before the start of the Second World War, aviation enthusiast and engineer Alexander Martin Lippisch, was fascinated with tailless delta wing designs. Lippisch’s early work primarily involved the development of experimental gliders. Eventually, he made a breakthrough at the Deutsche Forschungsinstitut, where he worked as an engineer. His work at DFS would lead to the creation of the rocket-powered glider known as the DFS 194. As this design was a promising experiment in a new field, it was moved to Messerschmitt’s facility at Augsburg. After some time spent refining this design, it eventually led to the development of the Me 163 rocket-powered interceptor. While it was a relatively cheap aircraft, it could never be mass-produced, mostly due to difficulties associated with its highly volatile fuel. In 1942, Lippisch left Messerschmitt and ceased work on the Me 163 project. Instead, he joined the Luftfahrtforschungsanstalt Wien (English: Aeronautic Research Institute in Vienna) where he continued working on his delta-wing aircraft designs. In May 1943 he became director of this institution, and at that time the work on a supersonic aircraft was initiated.

In the later war years, among the many issues facing the Luftwaffe, was a chronic fuel shortage. Lippisch and his team wanted to overcome this problem by introducing alternative fuels for their aircraft. Luckily for his team, DFS was testing a new ramjet engine. They were designed to compress air which would be mixed with fuel to create thrust but without a mechanical compressor. While this is, at least in theory, much simpler to build than a standard jet engine, it can not function during take-off as it requires a high airflow through it to function. Thus, an auxiliary power plant was needed. It should, however, be noted that this was not new technology and had existed since 1913, when a French engineer by the name of Rene Lorin patented such an engine. Due to a lack of necessary materials, it was not possible to build a fully operational prototype at that time, and it would take decades before a proper ramjet could be completed. In Germany, work on such engines was mostly carried out by Hellmuth Walter during the 1930s. While his initial work was promising, he eventually gave up on its development and switched to a rocket engine instead. The first working prototype was built and tested by the German Research Center for Gliding in 1942. It was later tested by mounting the engine on a Dornier Do 17 and, later, a Dornier Do 217.

The Dornier Do 217 was equipped with experimental ramjets during trials. Source: tanks45.tripod.com

In October 1943, Lippisch won a contract to develop the experimental P 11 delta-wing aircraft. While developing this aircraft, Lippisch became interested in merging his new work with a ramjet engine. This would lead to the creation of a new project named the P 12. In the early stage of the project, Lippisch and his team were not completely sure what to use as fuel for their aircraft, but ramjets could be adapted to use other types of fuel beyond aviation gasoline.

Unfortunately for them, LFW’s facilities were heavily damaged in the Allied bombing raids in June 1944. In addition to the damage to the project itself, over 45 team members died during this raid. To further complicate matters, the scarcity of gasoline meant that Lippisch’s team was forced to seek other available resources, such as different forms of coal. This led to the creation of the slightly modified project named P 13. In contrast to the P 12, the cockpit was relocated from the fuselage into a large fin. This design provided better stability but also increased the aircraft’s aerodynamic properties. The overall designs of the P 12 and P 13 would change several times and were never fully finalized.

The P 12 and 13 small-scale models, in both configurations, were successfully tested at Spitzerberg Airfield near Vienna in May 1944. The project even received a green light from the Ministry of Armaments. In the early stages of the project, there were some concerns that the radical new design would require extensive retraining of pilots. However, the wind tunnel test showed that the design was aerodynamically feasible and that the aircraft controls had no major issues. Based on these tests, work on an experimental aircraft was ordered to begin as soon as possible.

A proposed P 12 aircraft. Its designs changed greatly over time, before being finally discarded in favor of the letter P 13. Source: The Delta Wing History and Development

The DM-1 Life Saver

While working on the P 12 and P 13, Lippish was approached with a request from a group of students from Darmstadt and Munich universities. They asked Lippisch to be somehow involved in the P 12 and 13 projects. Lippisch agreed to this and dispatched one of his assistants under the excuse that for his own project, a wooden glider was to be built and tested. The previously mentioned student’s and Lippisch’s assistant moved to a small warehouse in Prier and began working on the Darmstadt 33 (D 33) project. The name would be changed to DM 1 which stands for Darmstadt and Munich.

At this point of the war, all available manpower was recruited to serve the German war effort. For young people, this often meant mobilization into the Army. One way to avoid this was to be involved in some miracle project that offered the Army a potentially war-winning weapon. It is from this, that numerous aircraft designs with futuristic, and in most cases unrealistic, features were proposed. Many young engineers would go on to avoid military service by proposing projects that on paper offered extraordinary performance in combat.

The students and Lippisch managed to nearly complete their DM1 test glider when the war ended. Source: airandspace.si.edu

While it was under construction, preparations were made to prepare for its first test flight. As it was a glider it needed a towing aircraft that was to take it to the sky. A Sibel Si 204 twin-engine aircraft was chosen for the job. However, this was not to be done like any other glider, being towed behind the larger aircraft. Instead, the DM-1 was to be placed above the Si 201 in a frame, in a similar combination as the Mistel project. The estimated theoretical speeds that were to be reached were 560 km/h (350 mph).

Allegedly, there were four different proposals for the DM’s that were to be fully operational. The DM 2 version was estimated to be able to reach a speed of 800-1,200 km/h (500 – 745 mph). The DM 3’s theoretical maximum speed was to be 2,000 km/h (1,240 mph) while the fate of the DM 4 is unknown. Here it is important to note that these figures were purely theoretical, as there were no supersonic testing facilities to trial such a design. It is unclear in the sources if these additional DM projects even existed, even if in only written form. We must remember that the whole DM 1 glider idea was made to help the students avoid military conscription and that Lippisch himself never saw the DM 1 as any vital part of the P 13.

In any case, the glider was almost completed by the time the war ended and was later captured by the Western Allies. Under the US Army’s supervision, the glider was fully completed and sent to America for future evaluation. It would then be given to the Smithsonian Institution.

A DM 1 test glider being under construction. Source: hushkit.net

The Siebel Si 204 was to be used as a carrier for the DM 1 glider for the expected first-flight tests. Due to the end of the war, this was never achieved. Source: www.silverhawkauthor.com

Work on the P 13

As the work on the P 13 went on, the name was slightly changed. This was necessary as different variations of the P 13 were proposed. The original P 13 received the prefix ‘a’ while the later project’s designation continued alphabetically for example P 13b. After a brief period of examination of the best options, the P 12 project was discarded in favor of P 13. The decision was based on the fuel that the aircraft should use. What followed was a period of testing and evaluation of the most suitable forms of coal that could be used as fuel. Initial laboratory test runs were made using solid brown Bohemian coal in combination with oxygen to increase the burn rate. The fuel coal was tube-shaped, with an estimated weight of 1 kg, and encased in a mesh container through which the granulated coal could be ejected. The testing showed serious problems with this concept. While a fuel tube could provide a thrust that on average lasted 4 to 5 minutes, its output was totally unpredictable. During the testing, it was noted that due to the mineral inconsistency of the coal fuel, it was impossible to achieve even burning. Additionally, larger pieces of the coal fuel would be torn off and ejected into the jet stream. The final results of these tests are unknown but seem to have led nowhere, with the concept being abandoned. Given that Germany in the last few months of the war was in complete chaos, not much could be done regarding the Lippish projects including the P 13a.

As more alterations to the original design were proposed its name was charged to P 13a. Here is a drawing of a P 13b that was briefly considered but quickly discarded. Source: The Delta Wing History and Development

In May 1945, Lippish and his team had to flee toward the West to avoid being captured by the advancing Soviets. They went to Strobl in Western Austria, where they encountered the Western Allies. Lippisch was later transported to Paris in late May 1945 to be questioned about his delta wing designs. He was then moved to England, and then to America in 1946. The following year, American engineers tested the DM 1 glider at the wind tunnel facility of the Langley Field Aeronautical Laboratory. The test seems promising and it was suggested to begin preparation for a real flight. A redesign of the large rudder was requested. It was to be replaced with a much smaller one, where the cockpit would be separated from the fin and placed in the fuselage. Ironically Lippish was not mentioned in this report, as technically speaking he was not involved in the DM 1 project. Nevertheless, he was invited for further testing and evaluation of this glider. If this glider and the Lippish work had any real impact on the US designs is not quite clear.

Despite no aircraft being ever completed, one full-size replica of this unusual aircraft was built after the war. It was built by Holger Bull who is known for building other such aircraft. The replica can now be seen at the American Military Aviation Museum located in Virginia Beach.

An interesting full-size replica of the P 13 located at the American Military Aviation Museum. Source: Wiki

Technical characteristics

DM 1

The DM 1 glider was built using wooden materials. Given that it was constructed by a group of young students, its overall design was quite simple. It did not have a traditional fuselage, instead, its base consisted of a delta wing. On top, a large fin was placed. The cockpit was positioned in front of the aircraft within the large vertical stabilizer. To provide a better view of the lower parts of the nose, it was glazed. The landing gear consisted of three small landing wheels which retracted up into the wing fuselage. Given that it was to be used as a test glider, no operational engine was ever to be used on it.

The DM 1 side view. In contrast to the later P 13a design, the pilot’s cockpit position was placed above the wings. This was necessary as the engine was to be added. Source: airandspace.si.edu

A DM 1 was captured by the Allies after the war. Its unique shape is quite evident in this photograph. Source: Wiki

A good example of DM 1 (to the right) and P 13a models that showed the difference between these two. The P 13a could be easily distinguished by its engine intake and the different position of the pilot cockpit. Source: Wiki https://imgur.com/a/QW7XuO5

P 13a

The P 13 is visually similar but with some differences. The most obvious was the use of a ramjet. This means that the front, with its glazed nose, was replaced with an engine intake. Here, it is important to note, that much of the P 13a’s design is generally unknown, and much of the available information is sometimes wrongly portrayed in the sources. The P 13a never reached the prototype stage where an aircraft was fully completed. Even as the war ended, much of the aircraft’s design was still theoretical. Thus all the mentioned information and photographs may not fully represent how the P 13 may have looked or its precise characteristics, should it have been finished and built.

The exact ram engine type was never specified. It was positioned in the central fuselage with the air intake to the front and the exhaust to the back. As the main fuel, it was chosen to use small pieces of brown coal which were carried inside a cylindrical wire mesh container. The total fuel load was to be around 800 kg (1,760 lbs). Combustion was to be initiated by using small quintiles of liquid fuel or gas flames. The overall engine design was changed several times during the work on the P 13 without any real solution to the issues of output consistency. Given that the ramjets could not work without an air thrust, an auxiliary engine had to be used during take-off, though a more practical use would be to tow the P 13 until it could start its engine. A rocket takeoff ran the risk of the engine failing to ignite, leaving the pilot little time to search for a landing spot for his unpowered aircraft.

An illustration of the proposed P 13a engine interior. The use of coal as fuel may seem like a cheap alternative but given that this kind of technology was never employed may be an indication of its effectiveness. Source: theaviationgeekclub.com

The wing construction was to be quite robust and provided with deflectors that would prevent any potential damage to the rudders. The wing design also incorporated a sharp metal plate similar to those used for cutting enemy balloons cables. These proposed properties of the wings are another indicator that the P 13 was to be used as an aircraft rammer. Another plausible reason for this design was the fact that given it had no landing gear the aircraft design had to be robust enough as not to be torn apart during landing. The wings were swept back at an angle of 60 degrees. The precise construction method of the wings (and the whole P 13 a on that matter) are not much specified in the sources. Given the scarcity of resources in late 1944 it is likely that it would use a combination of metal and wood.

A drawing of the P 13a interior. Its overall construction was to be more or less standard in nature. This could not be said for the aircraft’s overall shape design. Source: D. Sharp Luftwaffe Secret Jets of the Third Reich

The fin had to be enlarged to provide good flight command characteristics. In addition, given that the position of the cockpit was in the fin, it had to be large. The fin was more or less a direct copy of one of the wings. So it is assumed that it too would share the overall design. The fin was connected to the aircraft by using four fittings.

The cockpit design was to be simple and cheap to build. The pilot was to have plenty of room inside the large fin. The cockpit was provided with a large glazed canopy that provided a good view of the front and sides. The seat and the instrument panel were bolted to the cockpit floor and walls. These could be easily detached for repairs. The instrument panel was to include an artificial horizon indicator, altimeter, compass, and radio equipment, Given that it was to operate at a high altitude oxygen tanks were to be provided too. Despite being intended to fly at high altitudes the cockpit was not to be pressurized. Another unusual fact was that initially the P 13 was to have a crew of two, but this was quickly discarded.

A possible example of how the inside of the pilot cockpit may have looked. Source: D. Sharp Luftwaffe Secret Jets of the Third Reich

Here it is important to note that the version of the P 13 with the large fin is often portrayed as the final version of this aircraft. However, Lippisch never fully decided whether he should go for this version or the second that used a smaller fin with the pilot cockpit placed above the engine intake. Depending on the proposed version they are drastically different from each other. Lippisch, for unknown reasons, presented the British intelligence officer with the version that used the smaller fin and the American with the second version.

During its development phase, many different alterations of the P 13 were proposed. Isource: D. Sharp Luftwaffe Secret Jets of the Third Reich

Landing operations were a bit unusual. To save weight no standard landing gear was to be used. Instead, Lippisch reused the Me 163 landing procedure. As the P 13 was immobile on its own, a small dolly would be used to move the aircraft. Once sufficient height was reached the dolly was to be jettisoned. In theory, this was an easy process, but in practice, this operation offered a good chance of failure and was much less safe than conventional landing gear. Sometimes the dolly either failed to eject or it bounced off the ground hitting the Me 163 in the process, with often fatal consequences.

The Me 163 which did not have traditional landing gear, had to be prior to the flight, transported to the airfield before launching into the sky. Source: warbirdphotographs.com

The aircraft was to land with the nose raised up from the ground. This limited the pilot’s view of the ground. In addition due to its small size and in order to save weight, nontraditional landing gear was provided, instead, it carried a landing blade skid. To help absorb the landing impact, additional torsion springs were to be used. This bar had to be activated prior to the landing, it would emerge from beneath the aircraft fuselage, with the rotation point located at the front. Once released it was to guide the aircraft toward the ground. After that, the torsion springs were to soften the landing. This whole contraption seems like a disaster just waiting to happen and it’s questionable how practical it would be.

A drawing that showed how the P 13a was to land using a guiding landing blade skid. Source: D. Sharp Luftwaffe Secret Jets of the Third Reich

One interesting feature of the P 13 was that it could be easily disassembled into smaller parts which would enable effortless transport. Another reason was that due to the engine’s position in order to make some repairs or replacement of the engine, the remaining parts of the wing and the large fin had to be removed.

Was it an aircraft rammer?

The precise purpose of the P 13a is not quite clear, even to this day. Despite being briefly considered for mass production, no official offensive armament is mentioned in the sources. So how would the P 13a engage the enemy? A possible solution was that it would be used as a ram aircraft that was supposed to hit enemy aircraft damaging them in the process. In an after-the-war interrogation by British officers, Lippisch was asked if the P 13 was to be used as an aerial ram aircraft. Lippisch responded the following “

“.. The possibilities of using the P.13 as a ramming aircraft had been considered but Dr Lippisch did not think that athodyd propulsion was very suitable for this purpose owing to the risk of pieces of the rammed aircraft entering the intake. This would be avoided with a rocket-propelled rammer…”

This statement contradicts the building description issued by the LFW issued in late 1944. In it was stated the following about this potential use. “…Due to tactical considerations, among other things, the speed difference of fighters and bombers, preferably when attacking from behind, though the thought was given to the installation of brakes .. and although ample room for weaponry is present, the task of ram fighter has been taken into account – so that the ramming attack will not lead to the loss of the aircraft, thanks to its shape and static structure.”

This meant that this concept may have been considered by Lippisch at some point of the project’s development. The P 13 overall shape resembles closely to aircraft that was intentionally designed for this role. That said, it does not necessarily mean that the P 13 was to ram enemy aircraft. The use of such tactics was considered but their use was discarded, as it was seen as a futile and flawed concept. The project itself never got far enough to have an armament decided for it.

The precise method of how to engage the enemy aircraft is not clear as the P13a was not provided with any armament. It is sometimes referred to in the sources as it was to be used as a ram aircraft. Source: theaviationgeekclub.com

Conclusion

The Lippisch P 13 is an unusual aircraft project in nearly all aspects. Starting from its shape, which proved, at least during wind tunnel tests, that the concept was feasible. On the other hand, its engine seems to have simply been abandoned after discouraging test results. It is unlikely that such a combination would have worked to the extent that the P 13 designer hoped it would. During the testing, they could not find a proper solution to providing a constant thrust with sufficient force to reach a speed that was expected of it. So the whole concept was likely to be doomed from the start.

The DM 1 however, while it was never seriously worked on by Lippisch himself, managed to save a group of young students who used the project to avoid being sent into combat.

DM-1 Specifications
Wingspans	5.92 m / 19 ft 5 in
Length	6.6 m / 21 ft 7 in
Height	3.18 m / 10 ft 5 in
Wing Area	20 m² / 215 ft²
Engine	None
Empty Weight	300 kg / 655 lbs
Maximum Takeoff Weight	460 kg / 1,015 lbs
Maximum Speed	560 km/h / 350 mph (gliding)
Landing speed	72 km/h / 45 mph
Release altitude	8,000 m (26,240 ft)
Crew	1 pilot
Armament	None

Theoretical Estimated Lippisch P 13 Specifications
Wingspans	5.92 m / 19 ft 5 in
Length	6.7 m / 21 ft 11 in
Height	3.18 m / 10 ft 5 in
Wing Area	20 m² / 215 ft²
Engine	Unspecified ramjet
Maximum Takeoff Weight	2,300 kg / 5,070 lbs
Maximum Speed	1,650 km/h / 1,025 mph
Flight endurance	45 minutes
Fuel load	800 kg / 1,760 lb
Crew	1 pilot
Armament	None mentioned

Illustrations

The Lippisch DM-1, unnecessary to the overall project, it none the less allowed a group of students to escape military service.

Credits

Article written by Marko P.
Edited by Henry H.
Ported by Marko P.
Illustrated By Medicman11

Source:

A. Lippisch (1981) The Delta Wing History and Development, Iowa State University Press
D. Nesić (2008) Naoružanje Drugog Svetsko Rata-Nemačka. Beograd.
D. Monday (2006) The Hamlyn Concise Guide To Axis Aircraft OF World War II, Bounty Books.
J. R. Smith and A. L. Kay (1972) German Aircraft of the WW2, Putham
B. Rose (2010) Secret Projects Flying Wings and Tailless Aircraft, Midland
D. Sharp (2015) Luftwaffe Secret Jets of the Third Reich, Mortons

Northrop’s Early LRI Contenders

June 12, 2020Cold War, USCold War, Concept, delta wing, interceptor, nuclear, USAFMedicman11

United States of America (1953)
Long Range Interceptor Proposals [None Built]

Detailed drawing of the N-144, with cutaway section

Born from the Long Range Interceptor program, the first of Northrop’s contenders were three aircraft that had large delta wings and overall similar shapes and designs. The first, the N-126, started as a modified version of Northrop’s F-89D Scorpion fighter but would become its own unique aircraft by 1954. The second, the N-144, was a large four-engine interceptor design that dwarfed current bombers of the time and could carry an impressive arsenal. The third, the N-149, differed the most from its two siblings. It was much smaller and used General Electric engines over Wright engines. The N-144 was the most successful out of the entire program, but would prove to be too costly and a maintenance nightmare if produced. The N-126 and N-149 would also not meet expectations, as did none of the other competitors in the doomed program.

The LRI Competition

At the start of the Cold War, it was realized that if a Third World War would ever happen, defending the mainland United States from airborne threats would be a top priority. ICBMs and nuclear missiles are the go-to threat everyone imagines when they think of the Cold War, but these wouldn’t be operational until the late 1950’s. In the early years, nuclear weapons would be deployed by strategic bombers and these would be the major threat. Intercepting these long range aircraft would be of the utmost importance if the war went hot in the 1950’s. Developing an aircraft able to reach these bombers and destroy them led to the creation of the modern interceptor. Most countries had begun developing an interceptor of their own. At the forefront was the United States Long Range Interceptor program (LRI). This program originated in early 1952, with Major General L.P. Whitten of the Northeast Air Command noticing that a capable aircraft would be able to takeoff and intercept enemy bombers using the warning time of the Semi-Automatic Ground Environment (SAGE) system, which was an integrated defense network of SAM, radar and fighters across the US and Canada, able to intercept enemy bombers well before they were able to reach the United States. Although the idea was put out, no official requirements for the idea came about until December of 1953, when the Air Council put out extremely demanding needs. The aircraft would need to be airborne in two minutes from getting the scramble alert. Maximum speed would be Mach 1.7 with a range of 1,000 nm (1,850 km). Combat ceiling would be 60,000 ft (18,000 m) with a climb rate of 500 ft/min (150 m/min). The aircraft would be minimally armed with forty-eight 2.75 inch rockets, eight GAR-1A Falcon AAMs or three unguided nuclear rockets. This requirement became known as Weapon System WS-202A. Most companies developed submissions, but McDonnell and Northrop had an early start with a long range interceptor design being conceived very early on, well before an official requirement had been requested. Northrop had three aircraft designs that would fit the requirement for WS-202A; the N-126, N-144 and N-149. All three were visually similar to each other and shared concepts and equipment with one another.

Northrop N-126: The Delta Scorpion

Bottom view of the N-126 Delta Scorpion model [US Secret Fighter Projects]

The first of the designs Northrop submitted was the N-126 Delta Scorpion. This aircraft actually began development months before an official requirement was put out. The design was submitted in February of 1953 and was essentially a Northrop F-89D Scorpion modified with a new delta wing design and Wright YJ67 engines. The aircraft received a performance review sometime in 1953 along with McDonnell’s two-seat version of the F-101 Voodoo. Neither design was chosen for production. The N-126 did show promise, as it came close to meeting the very first requirements and it was supported by the Air Defense Command. However, the predicted first flight in twenty-one months was a bit too optimistic and the design was disliked by the United States Air Force Headquarters, as it didn’t exactly meet requirements compared to the F-101 variant. Northrop pushed this early design and adamantly tried to acquire production.

Front quarter view of the N-126 Delta Scorpion model [US Secret Fighter Projects]

They were quick to begin working on an improved design that would be longer and yield better results. It took over fifty concept designs before they found a suitable improvement. The aircraft itself no longer resembled the F-89D Scorpion it got its name from, but the name would stick until the end of the project. This new design was submitted in August of 1954. The N-126 was now much sleeker, with a forty-five degree delta wing and two underwing Wright J67-W-1 engines (Allison J71-A-11 engines were a weaker alternative choice). The delta wings all three projects used provided lower weight than generic straight wings and minimized drag. The trailing edge of the wing would have a split speed brake on the outer surface, an aileron located in the middle and a feature on the inboard section only referred to as an “altitude flap”. For the landing gear, a bicycle configuration with two wheels on each gear would be mounted directly under the aircraft, with a smaller landing gear being placed under the wings.

For armament, the aircraft would use the required eight Falcon AAMs and forty-eight rockets being mounted in a 20 ft weapon bay. Four external hardpoints would allow extra ordnance to be carried, such as bombs or extra missiles. Alternative loadouts included any combination of four AIR-2A unguided nuclear rockets, six Sidewinders, or two Sparrow guided missiles. The N-126 would use the Hughes E-9A fire control system, one of the few remnants carried over from the F-89. The E-9A would be linked to a long-range search radar that would have a range of 100 nm (185 km). For fuel, one large internal tank and two smaller tanks in the wings would hold 4,844 gal (22,025 l). Extra drop tanks could be mounted under the wings and offer an additional 1,600 gal (7,275 lit). For its predicted mission, the N-126 would be able to launch and engage enemy bombers twenty-seven minutes after scramble. Northrop expected a prototype would be ready for a first flight by June of 1957.

Northrop N-144: The Monstrous Interceptor

Color photo of the N-144 model [US Secret Fighter Projects]

The N-144 was the second design Northrop submitted. It was made to offer the best results in regard to the WS-202A requirements. It resembled the N-126 but was much larger and had four J67 engines. The N-144 dwarfed its siblings, competitors, and even several current bombers of the time. With a wingspan of 78 ft and a length of 103 ft, this was no small aircraft. In comparison, the Convair B-58 supersonic bomber had a wingspan of 56 ft and a length of 96 ft (interesting to note, a plan to convert the B-58 into a long range interceptor was proposed).

Its appearance wasn’t the only thing carried over from the N-126. The E-9A fire control system, its accompanying scanner, and its landing gear design (now with four wheels on the main gear) were all reused in the N-144. The N-144 also had a forty-five degree delta wing like the N-126. The N-126 and N-144 would both have their engines on pylons on the wings. This configuration allowed much more powerful engines to be used and a simpler intake system compared to having the engines be built into the body, not to mention the layout being much safer in the event of a fire.

Top down view of the N-144 model. Note the 45 degree delta wing [US Secret Fighter Projects]

The N-144 utilized many features that would directly improve the aerodynamics of the aircraft. The aircraft would have low wing loading which would increase its cruise altitude and improve takeoff and landings. The addition of a horizontal tail, which isn’t often seen in delta wing designs, gave the N-144 improved handling and stability over designs that lacked the horizontal tail (see the Convair F-102 Delta Dagger for example). When the aircraft would be supersonic, the wing would have a chord flap that would retract into the wing to reduce drag. Area ruling was a feature involving tapering the center of the fuselage which would reduce drag while the aircraft was flying at supersonic speeds. Most current delta wing designs utilized area ruling, but none of Northrop’s interceptors surprisingly did. Northrop ruled that the advantages would only affect supersonic flight, and not provide anything useful during subsonic flight. Having no area rule also made the aircraft simpler in design and easier to produce. Northrop’s studies into the delta wing expected to see performance increase as time went on, with more modifications and better engines being used on the N-144 if it went into production. With these expected improvements, Northrop theorized a 14% improvement in top speed and service ceiling.

Frontal view of the massive N-144 model. The size of its engine pods are evident. [US Secret Fighter Projects]

For armament, the N-144 would still utilize the standard eight Falcon AAMs and forty-eight rockets, but could also carry twelve Falcon AAMs, six AIR-2A Genie (Ding Dong) rockets, 452 2.75 in FFAR rockets or 782 2 in (5.1 cm) rockets internally in any order. External hardpoints could also be fixed for carrying bombs or more ordnance. For fuel, a large fuel tank would be in the wings and fuselage and could carry 6,910 gal (31,419 l) of fuel. Given the size of the aircraft, Northrop advertised that it could be used in alternative roles.

Northrop N-149: The Opposite End

Model of the N-149. The additional fuel tanks can be seen. [US Secret Fighter Projects]

The N-149 was the third and final design submitted by Northrop for WS-202A. Submitted in July of 1954, the N-149 was almost the polar opposite of the N-144. Instead of opting for raw power and utilizing four engines, the N-149 was meant to be the smallest option available while still performing just as well as its competitors. In comparison, the N-126 would be 85 ft (25.9 m)long with a wingspan of 62 ft (19 m), while the N-149 would be 70 ft (21.5 m) long with a wingspan of 50 ft (15.5 m). This size decrease would save cost, space and fuel consumption. The N-149 used the same wing layout as the previous entries and would also retain the E-9A fire control system and accompanying radar. Given the advancements of the N-144’s wings, it is likely the N-149 would also benefit from them as well. The N-149 did not use Wright J67 jet engines like the N-126 and N-144, but would instead use General Electric J79 engines. These engines were longer than the J67 but would benefit the aircraft, given its small size, to achieve the required speed and rate of climb. The bicycle landing gear with outer wing gear was once again used, but now with two wheels on each gear like the N-126. The armament for the N-149 was less than its predecessors, but it would make up for weapons in the amount able to be built. Once again, eight Falcon AAMs and forty-eight 2.75in rockets were standard, but alternative armaments would be a single Sparrow AAM, four Sidewinder AAMs, another 105 2.75 in rockets or 270 2 in rockets. Additional armament could be mounted on four external hardpoints like the N-126 and N-144, however, two of these would be taken up by external fuel tanks. These tanks would be 600 gal (2,730 l). The majority of the fuel would be in a large tank that spanned the fuselage and into the wings and would carry 2,050 gal (9,320 l) of fuel. Northrop expected a first flight of the aircraft by the summer of 1957.

The Program Concludes

Detailed drawing of the N-149 with cutaway

Although Northrop is the center of this article, Boeing, Douglas, Lockheed, Martin, McDonnell, North American, Chance-Vought, Grumman and Convair all submitted designs. When the assessment of all the designs was completed, it was concluded that none of the proposals exactly met up the set requirements. The N-144, however, came the closest to meeting the specification. After assessment, the N-144 had a predicted speed of Mach 1.76, a combat ceiling of 58,500 ft (17,800 m) and a combat range of 1,015 nm (1,880 km).

McDonnell’s design came close, as it could go faster and reach the same altitude, but its range was much less compared to the N-144. Materials Command was not too keen of the N-144 and it is obvious why. The cost, production and maintenance of it would be tremendous. Given its four engines, the aircraft would require much more maintenance compared to its two-engine competitors. Producing such a large aircraft would be extremely costly given its size and engine count. The best option for performance would also be the worst option considering its cost.

Its siblings didn’t meet the specifications as well. No reason was put out as to why the N-126 failed the competition, but given the state of the program, it can easily be assumed it didn’t meet either the range, speed, or altitude requirements. The N-149 did have a specified reason for its rejection, though. After taking off at full power and reaching its maximum height, it would only offer 20 minutes of flight, with 5 minutes at full power for combat. Having your aircraft destroy as many bombers before reaching their target is necessary and only 5 minutes wouldn’t be sufficient to fulfill its duty. Ultimately, WS-202A wouldn’t produce any aircraft. The requirements had gone too high, and the companies wouldn’t be able to produce a cost effective aircraft in time that would meet the expected specifications. The program would go on to become the new LRI-X program in October of 1954, and Northrop would be one of three companies tasked with creating a new interceptor, which their Delta-Wing trio would surely influence in a number of ways.

Variants

Northrop N-126 (February 1953) – The 1953 N-126 Delta Scorpion was an improvement upon the F-89D Scorpion by having a delta wing and YJ67 engines.
Northrop N-126 (1954) – The 1954 version of the N-126 no longer resembled the F-89 but was now longer and more streamlined.
Northrop N-144 – The N-144 would be the second design submitted to the LRI competition. It was much larger than the other two submissions and would utilize four engines.
Northrop N-149 – The N-149 was the smallest of the three designs and was meant to be the best performing for its size. It looked visually similar to the N-126 but would carry slightly less ordnance and utilize Gen Elec XJ79-GE-1 jet engines over the Wright J67-W-1s.

Operators

United States of America – All three designs would have been operated by the United States Air Force had they been constructed.

Northrop N-126 Delta Scorpion (1954) Specifications
Wingspan	62 ft 3 in / 19 m
Length	85 ft / 25.9 m
Wing Area	1,050 ft² / 97.7 m²
Engine	2x 13,200 Ibs ( 58.7 kN ) Wright J67-W-1 Jet engines
Weights	75,830 lbs / 34,400 kg (Gross)
Fuel Storage	4,844 gal / 22,025 l
Maximum Speed	1,183 mph / 1,903 km/h at 35,000 ft / 10,700 m
Cruising Speed	793 mph / 1,276 kmh
Range	800 nm / 1,500 km
Climb Rate	2.45 minutes to 40,000 ft / 12,000 m
Maximum Service Ceiling	59,600 ft / 18,000 m (Point Interception Role) 56,200 ft / 17,000 m (Area Interception Role)
Crew	1 Pilot 1 Radar Operator
Main Proposed Armament	8x GAR-1 Falcon AAM 48 2.75in (7 cm) FFAR
Alternative Armament Loadouts	4x Ding Dong Unguided Nuclear Rockets 6x Sidewinder AAMs 2x Sparrow AAMs 1x 1,640 lbs (744 kg) bomb

Northrop N-144 Specifications
Wingspan	78 ft 10 in / 24 m
Length	103 ft 6 in / 31.5 m
Wing Area	1,700 ft² / 158.1 m²
Engine	4x 13,200 Ibs ( 58.7kN ) Wright J67-W-1 Jet engines
Weights	113,700 lbs / 51,500 kg (Gross) 91,600 Ibs / 41,550 kg (Combat)
Fuel Storage	6,910 gal / 31,420 l 44,940 Ib / 20,390 kg
Maximum Speed	(Mach 2.04) 1560 mph / 2520 km/h at 34,000 ft / 10,000 m
Cruising Speed	(Mach 1.06) 810 mph / 1300 km/h
Range	1,015 nm / 1,880 km
Climb Rate	1.9 minutes to 40,000 ft / 12,000 m
Maximum Service Ceiling	63,000 ft / 19,202 m (Point Interception Role) 60,000 ft / 18,288 m (Area Interception Role)
Crew	1 Pilot 1 Radar Operator
Main Proposed Armament	8x GAR-1 Falcon AAM 48 2.75in (7 cm) FFAR
Alternative Armament Loadouts	Internal Storage 12x Falcon AAM 6x AIR-2 Genie (Ding Dong) Missiles 452 2.75 in FFAR 782 2in (5.1cm) Rockets External Hardpoints Unknown type of bombs mounted on 4 hardpoints.

Northrop N-149 Specifications
Wingspan	50 ft 10 in / 15.5 m
Length	70ft 6 in /21.5 m
Wing Area	700 ft² / 65.1 m²
Engine	2x 9,300 Ibs ( 41.3 kN ) Gen Elec XJ79-GE-1 Jet engines
Weight	43,400 Ibs / 19,700 kg
Fuel Storage	2,050 gal / 9,320 lit 13,310 Ibs / 19,690kg
Maximum Speed	(Mach 1.51) 1160 mph / 1860 km/h at 35,000 ft / 10,700 m
Cruising Speed	(Mach 1) 770 mph / 1230 km/h
Range	770 nm / 1,430 km
Climb Rate	3.1 minutes to 40,000 ft / 12,000 m
Maximum Service Ceiling	55,700 ft / 17,000 m (Point Interception Role) 52,800 ft / 16,000 m (Area Interception Role)
Crew	1 Pilot 1 Radar Operator
Main Proposed Armament	8x GAR-1 Falcon AAM 48 2.75in (7 cm) FFAR
Alternative Armament Loadouts	Internal Storage 1x Sparrow II AAM 4x Sidewinder AAMs 105x 2.75in (7 cm) rockets (original 48 on top of this) 270x 2in (5.1 cm) rockets External Hardpoints 4x Hardpoints for additional weapons (2 are used for fuel tanks)

Gallery

Illustrations by Ed Jackson – artbyedo.com

Northrop N-126 – Artist Impression of the Delta Scorpion in USAF Prototype Stage

Northrop N-144 – Artist Impression of the N-144 the in Late Prototype Stage

Northrop N-149 – Artist Impression of the N-149 in service with the 171 Fighter Interceptor Squadron, Michigan, circa 1960s

3-Way drawing of the N-126 Delta Scorpion [US Secret Fighter Projects]

3-Way drawing of the N-149 [US Secret Fighter Projects]

Underside quarter view of the N-126 model [US Secret Fighter Projects]

3 view drawing of the N-126 Delta Scorpion

A photo of the N-126 Delta Scorpion in wind tunnel testing

Colored photo of the N-149 model. Note the tail has been slightly damaged. [US Secret Fighter Projects]

Rear view of the N-149 model. Damage to the tail is evident here. [American Secret Projects: Fighters & Interceptors, 1945-1978]

Credits

Buttler, T. (2007). American secret projects : fighters & interceptors, 1945-1978. Hinckley: Midland.
Pace, S. (2016). The big book of X-bombers and X-fighters : USAF jet-powered experimental aircraft and their propulsive systems. Minneapolis, Minnesota: Zenith Press.
Written by Medicman11
Edited by Stan Lucian & Carbon
Illustrations by Ed Jackson – artbyedo.com

Saab 35 Draken

June 5, 2016Cold War, SwedenArchived, delta wing, Flygvapnet, Saab, Saab DrakenMario H Zorro

Sweden (1960)
Fighter Plane – 651 Built

A single-seat, single-engine interceptor/fighter for all-weather conditions, with low double delta wings, the Saab 35 Draken was developed in order to replace the Saab J29 Tunnan and the Saab J32 Lansen. Its first flight took place in 1955, being amongst the most advanced and remarkable fighters of its time. In 1960 it entered in service with the Flygvapnet.

Development of the Draken

Draken development started in 1949, following a requirement by the Flygvapnet for a single-seat cost-efficient interceptor with supersonic capabilities and high climbing rates, able to operate in short airstrips – or even highways, roads and unprepared runways – and easy to operate with high adaptability. As a result of both the requirements and development process, the result was a double-delta winged fighter that became the first European supersonic fighter, and also a high performance air-defence asset for Sweden. And on a similar fashion as the JAS 39 Gripen and JAS 37 Viggen, it was required the Draken to be serviced, refuelled and armed up to ten minutes by untrained ground personnel. A brake parachute was incorporated to reduce landing distance. Interestingly, a prototype was built expressly to test the double-delta wing concept: such was the Saab 210 ‘LilDraken’.

J35J in Flight - Swedish Air Force — J35J in Flight – Swedish Air Force

The Draken is also a product of the needs from a neutral nation willing to keep its neutrality, and geographically placed between the two block. This reason explains the requirements, but especially its high climbing rate capabilities, so to be able to engage high-altitude bombers and fighters – namely Soviet Union bombers and fighters. It also explains the need for STOL capacities, as the Flygvapnet was implementing a system of dispersed bases, asking for highways and roads to be used as airstrips from where the aircraft could be operating, and also to reduce damage and increase survival in case of attack.

Its very unique and remarkable double-delta wing design is also explained by the technical abovementioned requirements, which gave the aircraft very good high and low speed performances. This design made the Draken capable of executing the “Cobra” manoeuvre, and also to stand well against more recent designs, as air exercises in Austria evidenced. During development it was able to unintendedly exceed Mach 1 on its first afterburner flight. It could also sustain a force of 10G turning force. And it also had a safety feature, with the introduction of a ram turbine, placed under the nose, to provide emergency power.

Despite being conceptualized as an interceptor, it performed well in dogfights and was able to undertake ground attack, training, and reconnaissance missions as well. And it proved to be a very tough and resistant design, as it is among the few jet fighter designs to be in service for 50 years. Austria, Denmark, Finland, Sweden and US National Test Pilot School were the operators of the Draken.

The design was so unique that, in fact, the Draken was studied for the design and development of the F16XL experimental prototype.

Between 600 and 650 Draken were built, serving with the Flygvapnet until 1998, with the Finnish air force until the year 2000, the Danish air force until 1993, and the Austrian air force until 2005. The Draken also flew with the Flygvapnet ‘Acro Delta’ acrobatic team.

Design

The Draken is designed as a tailless middle double-delta wing fighter, with a single tail and a single engine (A Volvo Svenska Flygmotor RM6C, bestowing a maximum speed of 2125 km/h / 1,317 mph). Its double-delta wings allow good high and low speed performances. It also provided good fuel and armament capacity. The engine air inlets are located mid-wing at each side of the cockpit, featuring a characteristic egg shape.

Considered an easy-to-fly platform, yet not suitable for untrained pilots given the high sensibility controls, and being prone to ‘superstalls’ as a very stable platform with good low flight.

Although the avionics were in principle basic, the radar was a very sophisticated one – A PS-02/A based on the French radar Thompson-CSF Cyrano – integrated with an Ericsson version of a radar Thompson-CSF Cyrano S6 fire control system. It also incorporated VHF/UHF radio, a radio altimeter, a transponder, an IFF (Identification Friend or Foe) system, and the Swedish version of the Lear-14 autopilot. The seat of the pilot was reclined 30 degrees, similarly like the Viggen, to allow the pilot to resist G-forces. And the cockpit was fitted with air-conditioning and pressurization.

The engine in combination with the design, made the Draken a very manoeuvrable and fast fighter jet, with the braking parachute assisting the aircraft in the landing, reducing the distance required to reach a full stop. Earlier version of the Draken had two 30 mm Aden M/55 cannons, with later versions having only one cannon. Also some export versions kept the two cannons configuration.

An Advanced Cold Warrior

The Draken can boast not only being a radical and new design thus making it a very advanced one by the first decades of the Cold War. It was among the first fighters in incorporating an on-board radar and the earlier version of the data-link system, whose enhanced version was incorporated in the J 37 Viggen and the JAS 39 Gripen. Indeed, the Draken incorporated the STRIL 60 ground-control network that enable Draken pilots a firing guidance through the on-board instruments, being the system also capable to resist electronic jamming. Aside the fact of being the first European supersonic jet fighter, the Draken was the first fighter to have STOL capacities, and it was an aircraft that gathered valuable intelligence by producing photographic material of many new Soviet aircraft during the 70’s and 80’s. It also had a superior service ceiling in comparison with fighters of its times. Being a very resisting and long-endurance fighter, many pilots of the Draken stated that it was able to take on much newer designs.