Navalized Starfighter

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Lockheed L-242 Navalized Starfighter

The L-242 airplane was the result of two concurrent studies which were being pursued prior

to Lockheeds final submission to the OS-130 competition. The first such study was based on

the original requirements for a Navy fighter outlined in the first issue of OS-130. The second

study was for a day fighter airplane based on requirements for the United States Air Force

(which ultimately yielded the legendary F-104). In subsequent changes to OS-130, it became

apparent that Navy requirements were paralleling the concept of a day fighter being

developed for the Air Force and, as a result, Lockheeds proposal was essentially the airplanedeveloped for the Air Force modified to fulfill the requirements of a carrier-based airplane for

Navy use.

The table is a supplemental summary of the airplane characteristics and performance which

describes more clearly the combat capabilities and compares the airplane performance directly

with the final requirements of OS-130 and its Amendments.

Lockheed claimed that the L-242 would be entirely adequate to fulfill Navy requirements. It

had a top possible combat speed of 1,000 kts, corresponding to a Mach number of 1.74, which

was far in excess of the Mach 1.2 required. In addition, it had a combat radius of 495 miles,

by the use of droppable fuel tanks and combat at Mach 1.2, which exceeded the 400 miles

required.

Since this airplane was identical in general design to the F-104, its internal fuel capacity was

not q ite s fficient to f lfill the radi s specified in OS 130 Th s the 188 mile radi s ith a
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Introduction

In the development of the Lockheed L-242 design, the initial effort was spent on an airplaneto fulfill the requirements of a non-afterburning fighter which had a combat radius of 300

miles and a high speed of Mach 1. The development of this design was pursued with a

substantial effort until November 25, 1952 in spite of the fact that previous fighter

investigations by Lockheed had indicated that this level of performance was quite low and

that, on the basis of contemporary power plant data, a lighter smaller, airplane could be

achieved using an afterburner type of power plant. These design studies were continued,

however, because Lockheed was acutely aware of the Navys earnest effort to reduce the size,weight and complexity of its fighter aircraft.

The final design for the non-afterburning fighter did not include a main gear because of the

potential saving in weight provided by the mat landing system.

It was gratifying, in the comparison of the airplanes, to see that the supersonic design was not

vastly larger, and was only more complicated by the inclusion of the afterburner. It was the

considered opinion of Lockheed that the final requirements were more realistic and haveresulted in a more useful airplane for the Navy.

The following sections summarize the operational characteristics of the airplane, including

details of combat performance on alternate missions, combat armament, carrier suitability and

adaptability to later designs of carrier landing facilities. In addition, its maintenance features

and emergency escape provisions are outlined. Another section is devoted to the development

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Also apparent on the inboard profile was the fuselage stowage of the main gear, which

permitted the 3.4% thickness of the wing. In this location, the gear did not interfere with the

external wing stores nor did it prohibit the installation of external stores on the fuselage.

Finally, as shown in both Figures A and B, the ducts and the speed brakes had both been

placed on the side of the fuselage so that eventual modification of the airplane for mat landing

purposes would not involve any change in the aerodynamic configuration.

The general arrangement emphasized the simplicity of the airplane concept which was

necessary to obtain a really useable military weapon and to decrease the development,manufacturing and operational costs of the weapon system.

Combat Performance

Since the definition of a combat profile was difficult and the definition of the combat portion

of a mission could be interpreted in many ways, Lockheed created a summary of alternate

combat profiles to illustrate the full utility of the L-242. Several alternate combat profiles are

shown which were based on different missions where equipment was changed, or the missionpurpose was changed, from that of air-to-air fighter. Included in these alternate missions were

photo missions, bombardment operations, and trainer uses, all of which were found to be

easily provided by simple adaptation of the basic design.

Since the operation of a supersonic airplane had lead to many conjectures concerning the

limits of the airplane and its utility in combat maneuvers, considerable emphasis was place on

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Combat Armament

The basic Mark 16 sight installation, coupled with AN/APG-34 range radar, was believed tobe the simplest effective installation which could have been incorporated in the first models of

the L-242. Since the components of this sight and system were essentially developed, and

since training procedures were in existence which would develop pilots for this system, it was

felt that its installation in first-production models of the airplane was certainly justified. With

all of the armament components which were proposed for this system, with the exception of

the Aerowolf missile, it was believed to be the simplest possible sight arrangement.

The accompanying blueprints summarize the armament investigations which were made on

the airplane and showed the following capabilities.

1. Gun InstallationsAs shown in Figure 9, the basic Mark 12 guns were feasible to

install in the airplane with 500 rounds of ammunition as required. Alternatively, two

T-182 cannon could have been installed with 500 rounds of ammunition, or a single T-

171 cannon could have also been included with 500 rounds of ammunition. Lockheed

believed that the use of the T-171 cannon was worthy of substantial consideration,since it had the capability of firing almost as many rounds per second as the four Mark

12 guns, and its installation utilized only one armament compartment on the airplane,

leaving the other armament compartment available for the installation of additional

equipment or rockets. A comparison of the total armament weight for the several guns

indicated that for a given amount of fire power there was little to choose between the

installations from a weight standpoint.

2. Rocket InstallationsLockheed only presented one type of rocket installation,


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for the ability to put rockets in tandem. In any case, the sight had to be arranged for

either open or closed tubes, and, therefore, it would have been undesirable to combine

the fuselage rocket with tip rocket pods, since the ballistics of the two would havebeen different. Lockheed believed that the most desirable installation could have been

a combination of fuselage guns and tip rockets; or a combination of fuselage guns and

nose rockets. A final alternate would have been the use of a T-145 gun on one side

with rockets on the opposite side in the armament compartment. This was the lightest

combination of rockets and guns, and could have proven the simplest.

3. Missile InstallationsFigure 12 shows the installation of four Sparrow missiles and

four Aerowolf missiles on the airplane mounted on external racks on the wing. The

mid-wing arrangement made these installations relatively simple with no ground

clearance problem and the straight wing permitted their installation with the least

effect on balance. Lockheed gave special consideration to the airplane with the

Aerowolf, since this missile promised the simplest possible sighting arrangement,

eliminating range determination by the sight and eliminating the necessity of lead

computation. Lockheed believed usage of the Aerowolf missile as sole armament

merited special consideration for versions of the airplane which were to do interceptor

duty only. This would have permitted additional fuel in the fuselage, resulting inincreased radius or combat time.

4. External Bomb StoresSince the development of a fighter store was far from firm,

Figure 13 was compiled to show several alternative arrangements of external stores on

the airplane. It was worthy of note that the mid-wing arrangement of the airplane and

the landing gear installation had placed substantial emphasis on the ability of the

airplane to carry external stores with good ground and landing gear clearance. As

shown on Figure 13, the 1,000 lb Douglas store was easily carried, and a store of

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was used to supply target range information to the Mark 16 optical computing sight

from which gunfire was directed. A receiver-transmitter modulator, antenna, indicator

synchronizer, and control box were included in the proposed radar. The following is abrief itemized operational description of the system: a) ControlsOperation was

instigated by the pilot who had one primary control, an ON-OFF switch. Focus,

brilliance and receiver gain controls were added so that the picture could be adjusted

for optimum viewing. These latter controls could be set on the ground during pre-

flight checks. b) Antenna Scan CoverageThe search antenna, a paraboloid

approximately 22 in diameter, mounted in the aircrafts nose section, revolved at a

high rate of scan in a circular pattern about the airplanes centerline covering a conical

area of plus/minus 60 from this same center line. This coverage was accomplished by

mechanical movement of the antenna as it spun in either a spiral or nodding

manner. c)Indicator PresentationThe cathode ray tube indicator picture which was

used by the pilot for search and tracking purposes was a vertical type PPI display

which revolved in synch with the antennas rotation. In other words, the fighter

airplane was at the center of the scope and the sweep gave range and approximate

elevation and azimuth position information of the target. This is further illustrated in

Figure 14. Roman numeral I of Figure 14 shows how this presentation would haveappeared, based on a sweep range of 25 nm. The earths radar return would have

essentially formed an artificial horizon at the bottom of the scope and further given the

pilot his approximate altitude and attitude above the earths surface. Reference marks

showing range, as well as horizontal and vertical reference lines were etched on the

face of the cathode ray tube. Targets that appeared above the horizontal line were

those targets above the fighter and those which appeared to the right of the vertical

etched line were to the right of the airplane and those that appeared on the left of this

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installation as well as for service. The electronic equipment was designed as a package

unit to facilitate installation, maintenance, and service.

7. Economy of Tooling and Floor SpaceSimplified tension type joints used throughoutthe fuselage, and for joining the wings, kept master gauge costs to a minimum and

eliminated the need for any mating jigs. Each major section of the airplane was

designed to be assembled complete as a subassembly prior to mating. For example, the

forward fuselage, Station 122 to 378.5, could have been assembled complete,

including the canopy, nose landing gear, all doors and panels, etc. prior to mating to

the mid-fuselage. All doors, panels, etc. fell within the confines of each major

subassembly. This feature eliminated the need for portable apply-type drill fixtures

and any drilling or fitting operations after mating that was normally required for

members straddling joint planes. The final assembly line for the L-242 would have

been comparatively short since the operation would have consisted primarily of

mating the major sections, with installation work kept to a minimum.

8. Sub-Contracting the ExpensibilityEach component section of the L-242 was a

complete unit within itself, and was particularly adaptable for subcontracting. All units

were small enough to handle and ship with ease. All problems of tool coordination

were confined to a single section since all movable or removable members werecontained in the subsection. Single plane tension joints, and their related simplified

tooling, assured proper fits and mating of the various sections of the ship. The units of

the production breakdown were extended sufficiently to permit proper work

distribution for expanded production programs. Only the duplication of tools and

facilities required application to attain efficient mobilization rates. The manufacturing

methods and techniques used in the production of the L-242 were standard methods of

manufacture and were all used on contemporary Lockheed production aircraft.

9 F d F l St ti 122 t 378 5 Th f d f l d f


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bulkheads. This unit was assembled by framing the longerons to the bulkheads and the

joint ring at Station 508, and attaching the panel assemblies at the longerons. The tail

cone joint, at Station 618, was a simple tension type joint accessible from inside thefuselage. This section, along with the empennage, tail cone, and dive flaps, constituted

the service removable aft section, for engine access and exchange.

12. WingThe wing, which featured single unit skins and a series of spanwise beams,

attached to the side of the fuselage with a simple flat plane tension joint. Twenty-one

attaching bolts were accessible from inside the fuselage. The breakdown of the wing is

shown in Figure 27. All movable surfaces were to have been installed on the wing,

along with their respective actuator units, and rigged and checked out prior to being

mated to the fuselage. All control mechanisms for actuating the leading edge and

trailing edge flaps were located outside the primary wing box structure, thus

eliminating removable access panels in the box structure. Access was gained by

disconnecting the flap links and allowing the surface to hinge downward

approximately 90. The well, which housed the spoiler in the wing surface, was

designed to be sub-assembled complete with spoiler, cylinders, piping, etc., prior to

being installed in the wing structure.

13.EmpennageThe empennage was attached to the aft fuselage by four shear bolts atthe vertical fin beams. Access to this joint was gained through removable fillet

sections. The empennage contained the pitch control booster mechanism and was

capable of being completely rigged prior to mating to the fuselage. a) Vertical Fin

The vertical fin was composed of a leading edge assembly, a trailing edge assembly, a

tip, and intermediate ribs and skins. The two spars, which were aluminum forgings,

had integral fuselage attaching lugs and the rear spar could have had an integral

trunnion bearing for the stabilizer. This unit was assembled by positioning the leading

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it was entirely feasible to modify the airplane for use with an unconventional mat landing

system with attendant gains in combat time or radius.

Although the basic design had been limited to a fighter task, and even though a concentrated

effort had been spent reducing the size, complexity and weight of the airplane, Lockheed

believed the design was usable for several alternate missions including photo reconnaissance,

training and bombardment missions, even including the carrying of special stores. In spite of

the high speed potential, pilot emergency escape was entirely feasible with simple foolproof

mechanisms, thus aiding substantially in maintaining pilot morale. Combining a high speed

potential of Mach 1.74 (1,000 kts) with a combat altitude of 50,000 ft and combat radii

varying from 188 miles to 495 miles, depending upon fuel carried and type of mission, the L-

242 had the potential of performance to give air superiority or equality over any land-based

fighter that could have been developed in the equivalent time period. Furthermore, it had the

potential with contemporary programmed power plants of even higher performance and

greater range and these power plants could have been installed with very minor changes to the

basic airframe. Since the basic L-242 airplane was under development for use on a similar

mission by the Air Force, its concurrent development for Navy purposes was a logical

program. It provided both services with a maximum striking force for minimum developmentand production costs. Since the requirements as outlined by The Air Force and by the Navy

were roughly equivalent, it appeared uneconomical to develop two airplanes for such similar

missions.

Carrier Suitability

Figure 3 at the beginning of this article covered the performance of the airplane in and around

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to put the landing gear in such a position that the space made available by the removal of the

gear could have been utilized for alternate purposes.

Figure 17 is a diagram of the airplane inboard profile in which the landing gear has been

removed providing additional space and saving weight. It appeared that approximately 100

gals of fuel could have been put in this area, thereby extending the radius to the desired 300

miles. Lockheed suggested that when such a version of the airplane was considered the nose

gear be retained so that the cart for maneuvering the airplane on the carrier decks would only

have to be of the two-wheel variety once the nose gear had been extended. This could have

been of substantial assistance for take-off purposes and may have simplified the carrier

procedure. Furthermore, it would have permitted an external gear to be mounted on the wing,

thus facilitating the use of the airplane for training and ferrying purposes where the mat

landing facilities were not available.

Emergency Provisions

Figure 18 illustrates the provisions which were made for emergency egress from the airplane.

Considerable effort was spent analyzing the various means of exit from a high-speed airplaneincluding capsule exit, nose detachment, upward and downward ejection, including the actual

detail design of several of these alternates. After substantial consideration of this problem, it

was concluded that the simplest and, therefore, the most feasible method of high-speed exit,

resulted from a combination of complete airplane deceleration and downward ejection.

Experiments at the Lockheed Corporation under the development of the MX-883 supersonic

ram jet test vehicle had shown that the deceleration by parachute of large-weight vehicles was

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fashion. A further advantage of the configuration was that no wing folding mechanism was

necessary because of the short span, thereby eliminating one major item from maintenance

consideration.

Figure 20 is a diagram showing the access doors which were provided for servicing the

various components of equipment installed in the airplane. Unusual in this regard was the fact

that the electronic equipment was concentrated in two easily accessible locations with large

doors, and the wheel well doors within the fuselage provide additional access to portions of

the fuel system and hydraulic system of the airplane. Removing the tail for engine access was

a completely accepted maintenance feature with many advantages as pioneered in the F-80

series airplanes. A three-point attachment of the aft fuselage simplified its removal, and rails

were provided in the engine installation to permit the movement of the engine aft out of the

fuselage to such a position that the hoist attachment could have been made directly without

any special rigging. The engine was removed as an entity, including its afterburner. Of further

interest to maintenance was the fact that single-point refueling was incorporated in the design

which permitted rapid and simple refueling procedures, cutting down turn-around time.

Development Background for Design

Since a number of reasons for the airplane configuration were already outlined in the

discussion of the operational characteristics of the design, it is only necessary to make a brief

recapitulation of these reasons. There was a wealth of development background which

included the following major items of interest.

Wing Selection


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Navalized Starfighter