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Texas Aircraft Factory Me 262

taf-me262-1


The Texas Aircraft Factory Me 262 has its origins as an original 262 found in a dilapidated state at Willow Grove Naval Air Station, Pennsylvania. The aircraft, one of 11 examples taken to the United States in 1945 and, while none flew again, they did assist America with its jet aircraft development programme. There were no blueprints for the sheet-metal and wood 262 and the aircraft was gradually disassembled and all parts duplicated with enough to make five new aircraft. Its original Junkers engines were unreliable and needed overhauling every ten hours, and accordingly the new jet has two General Electric J-85 engines, giving twice the power and half the weight of the originals.

The Me 262 was a stunning design triumph, and the influence of the plane can still be seen in contemporary combat aircraft.  Swept wings, automatic slats, modular construction ... all were leading advances for the time.  More than any other aircraft of its day, the 262 was a fighter of absolutely unrivalled potential.

Still, despite this fortuitous blend of brilliance and chance, the Me 262 suffered from some well-known, and potentially catastrophic, weaknesses.  The engines, landing gear and brakes were all decidedly failure-prone, and these systems often caused the losses that the Allies could not.

One of the most overlooked aspects of the Me 262 Project lies in the extraordinary engineering and design work that has gone into integrating authenticity with safety.  In our desire to create a worthy duplication of the original aircraft, we have developed a number of ultra-low profile improvements which will greatly enhance operator and flight safety.  In the case of the J-85 replacing the Jumo 004, this is a rather overt matter; however, several other critical improvements have been quietly incorporated into the design to insure that these jets do not suffer the same fates as so many of their predecessors.

The precision engine castings were first proposed, then designed, by the late Steve Snyder.  As an aeronautical engineer, Snyder recognized that simply hanging a pair of J-85s on the Me 262 within oversized cowlings would create as many problems as it solved.  Differences in wing root forces, weight distribution, and the Center of Gravity would have completely altered the characteristics of the original Me 262.  His solution may have been borne of necessity, but it has emerged as one of the most innovative engineering feats in the entire effort.

Detailed castings have been made from an original Jumo engine, and all related accessory drive components, gearboxes and pressure lines will be precisely duplicated for surface-mounting.  When the access panels are opened, bystanders will see a historically accurate duplicate of a Jumo 004B engine.  Concealed deep within the casting, the modern powerplant will go all but completely unnoticed.

Perhaps most significantly, the entire assembly (when mated with the J-85) will closely duplicate the nacelle weight of the original Jumo 004.  In this respect, the original performance characteristics of the aircraft will be faithfully preserved.

As the landing gear was known to be another weak area on the original Me 262, a detailed analysis of landing gear stresses was directed.  This process revealed that a shock loading was generated by the spin-up forces of the large, heavy main wheels, which had to be reacted into by the wing landing gear attachment structure.  This placed a severe demand upon wing spar area and the airframe simply had to absorb these forces.  Over time, this would have had a devastating effect upon the aircraft.

In part, this problem can be traced to the history of the aircraft.  As originally designed, the Me 262 was equipped with a standard tail wheel (in lieu of the nose wheel).

In the taildragger configuration, the main gear was bolted directly onto the wing spar; however, the tricycle modification resulted in the creation of a separate wing torque box to be used as a mounting point.  This torque box was susceptible to damage, and very difficult to repair.

On the new Me 262s, this area has been reinforced with additional structural features, and the project is considering additional design changes that may further enhance the safety and longevity of the landing gear.  In addition to the wing box reinforcement, the nose gear mounting point and strut assemblies have been greatly improved.  In short, the entire system has been strengthened by a significant margin above what it was originally.

The braking systems of wartime German aircraft usually left something to be desired, and the Me 262 was no exception.  Brake fading and/or complete system failures were a common complaint.   

The notoriously ineffective nose wheel brake has been eliminated altogether, although the original brake lines will be duplicated for appearance.  Meanwhile, the  marginally performing drum brakes on the main gear have been replaced by a cleverly-integrated disc brake system. The improved disc brakes have been mounted within the wheel hub assembly itself, and have the capacity to stop an aircraft more than twice the weight of the Me 262.

Despite the fact that the nacelle weight will be roughly equal to that of the original Me 262, the power available to the pilot has still been significantly improved.  Since the characteristics of the airplane were well known at the 1,800 pound thrust level, every effort has been made to duplicate this performance envelope, and not create some "Super Me 262" class airplane.  Still, the fact remains that the increase in thrust is significant enough to consider some entirely new engineering aspects.

While a positive development in most respects, the added power can present new problems of its own.  For example, an engine failure during a full power takeoff could quickly result in an uncontrollable asymmetric thrust component.  The project engineers understood this problem, and developed a simple method to control the situation.
To address these issues and provide the pilot an accurate indication of actual power settings, the project has carefully modified the throttle assembly to be fitted with a throttle pressure spring which provides a positive force indication of engine RPM at 1,800 lbs. thrust.  In other words, the pilot will know when the maximum specification thrust levels of the Jumo 004 have been reached.

If the pilot desires additional power, he may push the throttles beyond the spring loaded position, holding them open against this spring pressure.  The actual hard stop for the throttles will be set at the J-85's maximum thrust setting, which is projected to be around 2,400 to 2,500 lbs., as mounted.  The additional power is reserved for two operational regimes.  On takeoff roll, prior to liftoff, and during climb.  Takeoff roll is initiated with full power, but it is then reduced to the original Jumo takeoff thrust level (1,800 lbs.) just prior to liftoff.  The excess power may be added once safe climb speeds of 260 Miles Per Hour are achieved.

The Junkers Jumo 004 is often remembered as a  temperamental and failure-prone powerplant.  Despite its advanced design, engine life was only between 10 and 25 hours, with the mean being at the lower end of this range.  These failures were anticipated to some extent and the Me 262 was designed to permit extremely rapid engine changes.
Contrary to popular belief, the 004A was a fairly sound performer when premium steels were used, and early versions were known to achieve a 200-250 hour service life.  However, the diversion of critical materials into U-boat production and other projects late in the war forced Junkers to produce the 004B model with only 1/3 of the high grade steel that had been used in the 004A.  It was to be a disastrous concession for the Me 262.

The introduction of inferior metals compounded an already problematic situation with the turbine blade design.  These blades were rigidly mounted, contributing to severe root stress relief problems.  The weaker metals simply could not withstand this kind of abuse and regular compressor failures were an inevitable consequence.

The General Electric J-85/CJ-610 series turbojet engine was originally designed in the 1960s for use in military applications.  Shortly thereafter, civil certification and production followed under the CJ-610 designation. The CJ-610 was quickly selected to power the popular Gates Learjet; meanwhile, its military cousin was called into service with such noteworthy combat aircraft as the F-5 Freedom Fighter and A-37 Dragonfly.  The resilience and forgiving qualities of the engine also made it a natural choice for training aircraft, and the J-85 was adopted for both the T-38 Talon and T-2J Buckeye.

The J-85/CJ-610 engine has a reputation for extreme reliability, allowing wide variations of inflow distortion.  It also places a minimal maintenance burden upon ground crews.  Proven in war and in peace over three decades, the engine is ideally suited to power this classic warbird well into the next century.

In aircraft applications, engine power is characteristically measured in terms of thrust versus weight.  The Jumo 004 was typical of early jet engines in that it was rather heavy, and not especially efficient. Production model 004s produced 1,980 lbs. of thrust, and weighed in at about 1,800 lbs.  Because of this, the engines were not extraordinarily effective at low airspeeds or altitudes or at reduced power settings. Long takeoff rolls (>3,000') were evidence of this phenomenon and, once aloft, power management became critical.  Abrupt throttle changes or rapid maneuvering often resulted in a flameout, or worse, a complete compressor failure. Each J-85 produces 2,850 lbs. of thrust, yet weighs only 395 lbs.  In simpler terms, the new engines offer nearly twice the power for less a quarter of the Jumo's weight penalty. The design dynamics of the Jumo engine castings are expected to reduce the thrust available by about 300 lbs. per engine.   Engineering estimates call for an actual power output in the vicinity of 2400-2500 lbs. per engine. Integration of the J-85 will bring many noticeable improvements.  Takeoff distances will be significantly shortened (<2,000'), and time-to-climb rates vastly improved.  Also, the J-85 responds well to varying power demands (including low power settings) and is highly tolerant of the kind of airflow disruptions that gave the Jumo such difficulty.

The Jumo-powered Me 262 was capable of level flight speeds in excess of 540 miles per hour at altitude; a trait that made it all but invulnerable to Allied escort fighters. Higher airspeeds were recorded under certain circumstances but, in general,  compressibility-related aerodynamic factors prevented the airframe from ever pushing into the high transonic range. Postwar tests in the West confirmed that at very high airspeeds airframe vibration levels and buffeting grow increasingly worse until the jet enters into a shallow dive and becomes all but completely uncontrollable.  Recently revealed Soviet documents demonstrate that this was also a major finding in Red Air Force flight testing of the Me 262.

In purely theoretical terms, the added power of the J-85 should give the new production Me 262s a speed advantage of at least 75 miles per hour over any previous generation Me 262. In the interest of safety, the Me 262 Project will be placing a placarded airspeed limitation upon the jets in the vicinity of 500 MPH.

Specific Fuel Consumption (SFC) values provide a quantifiable and uniform means of measuring a turbojet engine's efficiency.  All jets have an associated SFC, and for the Jumo 004, the correct figure is 1.39. In practical terms, this means that for each pound of thrust provided, the Jumo will burn 1.39 pounds of fuel per pound of thrust per hour.  With a typical fuel capacity of 1,800 liters, the range of the original Me 262 was approximately 600-650 miles (at altitude). The J-85 has a Specific Fuel Consumption value of .99, meaning that it will burn slightly less than one pound of fuel per pound of thrust per hour.  When compared to the Jumo, the J-85 is obviously some 40% more efficient.

This improvement will have a marked impact upon both the range and endurance of the of the new Me 262s.  A new Me 262 should be able to travel well over 1,000 miles on a single fuel load.

The project has three distinct aircraft variants.  Each of these airframes carries an original factory designation which corresponds to the basic design (A-1c or B-1c as appropriate).  The "c" suffix refers to the new J-85 powerplant and has been informally assigned with the approval of the Messerschmitt Foundation in Germany.  During the war, all operational Me 262s were "a" models, which signified installation of the Jumo 004 engine.  Experimental "b" models used the BMW 003 powerplant, leaving "c" as the next unassigned letter.

taf-me262-2


Configurations:
1.
Me 262 A-1c
Single-seat fighter variant
1 airframe

2.
Me 262 B-1c
Two-seat trainer variant
2 airframes

3.
Me 262 A/B-1c
Conversion (single or two-seat) variant
2 airframes

In January, 2003, the American Me 262 Project (formerly known as Classic Fighter Industries, Inc. and later Texas Aircraft Factory) successfully flight tested a near-exact replica of the Me 262 B-1c two-place variant, powered by GE J-85 engines.

Production

Werk Number: 501241
Type or Configuration: Me 262 B-1c (two seater)
TAF Name: Blue Nose
Me 262 Project Name: "White 1"
N262AZ

Werk Number: 501244
Type or Configuration: Me 262 A/B-1c
This model has been designed to be readily re-configurable between single-place and two-place models without sacrificing airframe authenticity or structural integrity.
TAF Name: Red Nose
Me 262 Project Name: Red 13 Tango-Tango
N262MS U.S Registration deregistered 01/18/2006
D-IMTT

Werk Number:
Type or Configuration: Me 262 A-1c (single seater)
TAF Name: Green Nose
Me 262 Project Name: White 3

Werk Number:
Type or Configuration: Me 262 B-1c (two seater)
TAF Name: White Nose
Me 262 Project Name:

Werk Number: 501243
Type or Configuration: Me 262 A/B-1c This model has been designed to be readily re-configurable between single-place and two-place models without sacrificing airframe authenticity or structural integrity.
TAF Name: Yellow Nose
Me 262 Project Name: White 8

 

 


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