Number 106 in the Series--Convair F-106 Delta Dart (1 of 4)

[j...@intgp1.att.com]

From j...@intgp1.att.com

The Convair F-106A Delta Dart is regarded by many as being the finest
all-weather interceptor ever built. It served on active duty with the
US Air Force for almost 28 years, much longer than most of its
contemporaries.

The F-106 had its origin in an early-1949 request by the USAF for an
advanced interceptor capable of supersonic performance that would
surpass the speed and altitude performance of new Soviet
intercontinental bombers which intelligence services warned would soon
be available. The North American F-86D Sabre, the Northrop F-89
Scorpion, and the Lockheed F-94 Starfire were all subsonic aircraft,
and were deemed to have insufficient growth potential to be able to
meet this new threat. This project came to be known as the "1954
Interceptor", after the year that new interceptor would supposedly be
entering service.

At that time, the Air Force recognized that the increasing complexity
of modern weapons made it no longer practical to attempt to develop
equipment, airframes, electronics, engines, and other components in
isolation and to expect them to work properly when they were put
together in the final product. To address this problem, the Air Force
introduced the "weapons system" concept, in which components of the
the new interceptor would be integrated with each other from the very
beginning, making sure that the various systems would be compatible
with each other when they were incorporated into the final aircraft.
The project was given the designation WS-201A, where WS stood for
"Weapons System". As originally conceived, WS-201A was a weapons
system consisting of air-to-air guided missiles, all-weather search
and fire control radar, all housed in an airframe capable of
supersonic flight.

The electronics package for the new WS-201A system came first.
Project MX-1179 was the designation given to that portion of the
project dedicated to the armament and electronic fire-control system
of the 1954 Interceptor. In October of 1950, the Hughes Aircraft
Company was named the winner of the MX-1179 contract. The Hughes
proposal consisted of a MA-1 fire control system acting in conjunction
with GAR-1 Falcon air-to-air guided missiles. For a brief time, the
Falcon missile was known as the F-98, a fighter designation.

The airframe part of the project was designated MX-1554. Proposals
for the airframe portion were requested by the Air Force on June 18,
1950. When the bidding closed in January of 1951, nine proposals had
been submitted by six different manufacturers. Republic submitted
three separate proposals, North American submitted two, and single
proposals were made by Chance-Vought, Douglas, Lockheed, and Convair.

On July 2, 1951, the Air Force announced that designs by Convair,
Lockheed, and Republic had been selected to proceed with preliminary
development. All three companies were to proceed with their designs
all the way to the mockup stage, with the design deemed most promising
at that time being awarded a production contract. Later, the USAF
deemed it too costly to carry through with three concurrent
development programs, and it cancelled the Lockheed project in its
entirety. The Convair and Republic entries were given the go-ahead to
proceed.

The Republic entry bore the company designation of AP-57, where the AP
stood for "Advanced Project". It called for an extremely advanced
aircraft capable of achieving a Mach 4 performance at altitudes of up
to 80,000 feet. This was clearly a quantum leap in the state of the
art for the early 1950s.

The Convair entry in the MX-1554 project was closely related to the
experimental XF-92A which Convair had built in 1948 as a test bed to
provide data for the proposed F-92 Mach 1.5 fighter. This work had
been performed in consulation with Dr. Alexander Lippisch, who had
done pioneering work in Germany on delta-winged aircraft during the
war, and Convair had become convinced that the delta configuration
provided a viable solution to the problems of supersonic flight. The
XF-92A had been the first powered delta-wined aircraft to fly, but the
F-92 project had itself been cancelled before any prototype could be
built.

On September 11, 1951, Convair received a contract for its delta
winged design which was assigned the designation F-102. Work on the
competing Republic design was also authorized, and that aircraft was
assigned the designation XF-103. However, the XF-103 was so far ahead
of the state of the art that it was deemed too risky to be a serious
contender for the 1954 Interceptor project, which made the F-102 for
all practical purposes the winner of the contest.

The Air Force authorized the fitting of a Westinghouse J40 turbojet in
the first few examples of the F-102, but later production aircraft
were to be powered by the appreciably more-powerful Wright J67
turbojet, which was a license-built version of the Bristol Olympus.
The J40-powered F-102 was to be capable of a speed of Mach 1.88 at
56,500 feet, with the J67 production version capable of Mach 1.93 at
62,000 feet.

In order to expedite the development of its 1954 Interceptor program,
the Air Force adopted the so-called "Cook-Craigie" program, named for
its originators, Generals Laurence C. Craigie and Orval R. Cook.
During the late 1940s, these two officers had developed a concept of
an aircraft development program in which the usual prototype stage
would be skipped. Instead of waiting to start full-scale production
until the prototypes had passed flight testing and the bugs had been
ironed out, the Cook-Craigie plan called for the delivery of a small
number of production aircraft during the flight testing phase so that
any major changes could be incorporated into permanent factory tooling
in order for combat-ready aircraft to be delivered when mass
production started. This program is inherently risky--it can produce
a new combat aircraft in a hurry if everything goes according to plan
during flight testing, but can result in a lot of costly and
time-consuming fixes in the field if unexpected problems turn up. The
Cook-Cragie plan is really viable only if there is a high degree of
confidence that the aircraft is really going to go into production.
Since the F-102 was basically a scaled-up XF-92A, the risk was deemed
work taking.

By December of 1951, it was apparent that the Wright J67 engine and
the MA-1 fire-control system would not be ready in time. This forced
the USAF to change its plans. At that time, the Air Force decided to
proceed with an interim version of its 1954 Interceptor, one which
could be introduced into service at an early date, pending the
availability of the fully-developed version at a later time. The
interim version was to be designated F-102A, with the fully-developed
advanced version being designated F-102B. The F-102A was to be
powered by the less-powerful Pratt & Whitney J57 turbojet, but the
F-102B was to retain the high-thrust J67. The F-102A would be
equipped with an interim fire-control system, but the F-102B would be
equipped from the outset with the highly-sophisticated fire control
system being developed by Hughes under project MX-1179.

Although the F-102A was considered only as an interim version pending
the availability of the F-102B, the F-102A ran into some unexpected
developmental difficulties and fell behind schedule. A lot of money
that had originally been planned for the F-102B now had to be diverted
into fixing the F-102A's problems. Consequently, the F-102B fell even
further behind schedule and began to lose some of its original high
priority.

By mid-1953, the MX-1179 fire control system (later to be known as the
MA-1) was slipping badly, and it took another year before an
experimental installation could be installed aboard a T-29B for
testing. At the same time, the Wright J67 engine was experiencing
difficulties of its own. The Air Force had to consider alternative
powerplants, and finally settled on the Pratt & Whitney J75, which was
an advanced version of the J57 which was used in the F-102A. The
substitution of the J75 engine for the J67 was approved in early 1955.

Seventeen F-102Bs were ordered in November of 1955. Their serials
were 56-0451/0467. The F-102B mockup was ready for inspection in
December of 1955. On April 18, 1956, the Air Force finalized the
F-102B production contract of the previous November, earmarking all of
the 17 aircraft ordered exclusively for testing. One prototype was to
be delivered in December of 1956, with the others to follow in January
of 1957.

On June 17, 1956, the designation of the F-102B was changed to F-106A.
This redesignation was a recognition of the past technical differences
that had distorted the original F-102 program and also a recognition
that the F-102B was by now a completely different aircraft from the
F-102A and was far more advanced.

In September of 1956, the Air Force specified that the F-106A would be
available by August of 1958 (some four years later than initially
planned) and that it had to compatible with the Semi-Automatic Ground
Environment (SAGE) up to a radius of 430 miles and as altitude of
70,000 feet. Interceptions would be accomplished at speeds of up to
Mach 2 at 35,000 feet. It was to be capable of launching air-to-air
guided missiles and rockets under the control of the Hughes MA-1 fire
control system.

The wing of the F-106A was virtually identical to that of the F-102A,
but the fuselage had a much more streamlined shape. The variable-ramp
air intakes were moved well aft of the nose and mounted closer to the
engine. The shape of the fin and rudder were changed and a new
undercarriage was fitted with steerable twin-nosewheels. As on the
F-102A, the all-missile armament was housed internally in a spacious
ventral weapons bay. The all-missile armament consisted of a single
Douglas MB-1 (Air-2A or 2B) Genie unguided missile equipped with a
nuclear warhead plus four Hughes GAR-3 radar- homing or GAR-4
infrared-homing (later redesignated AIM-4E and AIM-4G respectively)
air-to-air missiles. The Falcons were equipped with conventional
high-explosive warheads and could be launched in salvo or in pairs.
The unguided 2.75-inch missile armament of the F-102A was omitted.

The first F-106A (56-0451) was finally available by the end of 1956.
The first flight was made by Richard L. Johnson at Edwards AFB on
December 26, 1956. The second aircraft (56-0452) followed on February
26, 1957. They were both powered by the J75-P-9 engine. Early
testing reached a speed of Mach 1.9 and an altitude of 57,000 feet,
but this was still below expectations. In addition, the F-106A's
acceleration was well below Convair's estimates, and it took almost 4
1/2 minutes to accelerate from Mach 1 to Mach 1.7 and another 2 1/2
minutes to accelerate to Mach 1.8. With such poor acceleration, it
was felt that Mach numbers above 1.7 would not be tactically usable.

The poor speed and acceleration was cured by altering the aircraft's
air intake cowling and charging ejectors. The capture area of the
intake ducts was enlarged and the duct lips were thinned down. There
were also problems with the reliability of the J75-P-9 engine.
Eventually, the more powerful J75-P-17 engine was substituted, which
was rated at 17,200 lb.s.t. dry and 24,500 lb.s.t. with afterburner.
There were further problems with the MA-1 fire control system and with
the cockpit layout. Originally, the control column had occupied the
traditional center location, but was later moved to the side at USAF
insistence in order to ensure an unrestricted view of the Horizontal
Situation Indicator. This arrangement turned out not to be viable,
and the control column was later moved back to the center and provided
with a two-handed grip for both radar and aircraft control.

Initial aircraft had boundary layer fences as on the F-102, but
production aircraft had wing leading-edge slots instead. The first
twelve aircraft were temporarily designated JF-106A for flight tests,
but a total of thirty-seven (including the first two aircraft) were
used for flight test development.

In mid-1957, the F-106A was given the popular name Delta Dart.

Originally, the Air Force had planned to acquire 1000 Delta Darts to
equip some forty Air Defense Command (ADC) squadrons. However, by
1957 the delays in the F-106 program and the problems with the engine
and the fire control system had resulted in the necessity of other
interceptors such as the McDonnell F-101B Voodoo having been ordered
as a stop-gap measure, and the F-106 had lost some of its urgent
priority. For a while, serious consideration was given to cancelling
the entire F-106 program, or else to redesigning the aircraft as a
long-range interceptor. Although the F-106 survived intact, shortages
of funds caused a drastic cutback in the number of F-106As on order.
By September 1958 the total order of F-106 interceptors had been cut
by a factor of three, enabling only fourteen squadrons and a training
unit to be equipped. As a result, only a further 260 F-106As were
ordered. Since the cutback was so drastic, a decision mas made in
August of 1959 to convert all of the existing 35 F-106A test aircraft
to operational status (Model 8-24 standards) and turn them over to the
interceptor squadrons.

In September of 1958, an early F-106A (serial number 57-0235) was
allocated to Ames Research Center at Moffett Field in California for
tests of the MA-1 fire control system.

The first deliveries of the F-106A were made in May of 1959, initially
equipping the 498th Fighter Interceptor Squadron based at Geiger AFB
in Washington. This was no less than five years later than originally
planned. Even then, numerous problems kept the Delta Dart from being
declared fully operational until October 31, 1959. The remaining 13
squadrons were re-equipped with the F-106A by the end of 1960.

Initial operational deployment turned up all sorts of
problems--generator defects, fuel-flow deficiencies (particularly
acute in cold weather), and fuel-combustion-starter malfunctions. In
December of 1959, after a canopy had been accidentally jettisoned in
flight, all F-106s were temporarily grounded until the problem could
be fixed.

Production continued until December of 1960, the last aircraft off the
line being delivered as Model 8-31s. which were equipped with
improved MA-1 fire control systems, supersonic ejector seats, vertical
instrument displays, wings with revised camber (first tested on
57-0246), and with provision for 230 US-gallon external fuel tanks
mounted on pylons underneath the wings. The last 37 F-106A production
aircraft were provided with a better supersonic ejector seat that
would also work safely at low speeds. This new seat featured a dual
timing system one for low-altitude/low-speed ejection and one for
high-altitude/high-speed ejection.

Flight testing continued until early 1961, with each phase of the test
program turning up a whole host of problems which required important
engineering changes. Each change had to be defined, engineered,
reviewed, and approved for production before modification of aircraft
off the assembly line could begin. The Cook-Cragie production policy
only made problems worse, and by 1960, the Air Defense Command had so
many different F-106 configurations out in the field that maintenance
support was a nightmare.

A major modification project named *Wild Goose* was initiated in
September of 1960 to bring the earlier F-106s up to the latest
production standard. Early in 1960, ADC could list 63 changes in the
F-106A's fire control system and 67 changes in the airframe that would
be required to make early F-106s equivalent to the machines currently
coming off the production line. Lasting a full year, the program
involved roving AMC field assistance teams supported by ADC
maintenance teams working at ADC bases.

The last Delta Dart was delivered to the Air Force on July 20, 1961.

On December 15, 1959, a Delta Dart flown by Major Joseph W. Rogers
set a world's absolute speed record of 1515.6 mph at 40,500 feet.

Throughout its long service life, the F-106A was continually upgraded
and improved. The *Broad Jump* modification program started in late
1960 was a long-term program for general improvements in the F-106A.
This program was carried out by people at the Sacramento Air Material
Area, and it extended through early 1963. Among the changes
introduced by this program was the fitting of an infrared
search-and-track sight that could operate at low altitudes and against
varied backgrounds. The *Dart Board* program was another retrofit and
modification program which took place in 1961-62. This program added
a thermal flash blindness protection hood and a new Convair-designed
ejector seat which rotated into a horizontal position so that the
pilot was on his back before he ejected. In addition, the *Dart
Board* program finally fixed a problem with flame-outs from fuel
starvation which had affected earlier Delta Darts.

The MA-1 fire control system carried by the F-106A was initially quite
unreliable and was subjected to lots of in-service modifications in an
attempt to fix its chronic problems. In 1960, devices for long-range
detection and electronic counter-countermeasures equipment were added,
along with the capability for using angle chaff, silent lobing, and
pulse-to-pulse frequency techniques. Anti-chaff devices were added in
an effort to defeat enemy attempts to confuse the fire control system
by dropping bits of radar-reflective strips. The modification
programs involved 314 F-106As and were completed by the end of 1963.

In 1962, F-106As were fitted with a Sheaffer Spring Hook arrester
system designed to engage wires at the end of the runway in the event
of an landing overshoot, becoming the first USAF combat aircraft to be
so equipped. The F-106A was definitely NEVER intended for carrier-
based operations! :-)

In 1965, an new TACAN system was installed which used microelectronic
circuits and was one-third the size and weight of the existing system.
Zero-zero ejector seats were installed. Inflight refuelling
capability via a probe receptacle mounted on the fuselage behind the
pilot was added in 1967. The ability to carry 360 US-gallon
supersonic fuel tanks was added at the same time. In 1972, a clear
canopy was fitted for improved vision.

The F-106A operated in conjunction with the SAGE (Semi-Automatic
Ground Environment) network which was linked via the Hughes MA-1
fire-control system to the F-106. The MA-1 system was upgraded no
less than 60 times during the Delta Dart's long service life. It
operated by plotting the course needed to intercept an enemy aircraft,
automatically sighted the target, fired the air-to-air missiles, and
then automatically placed the F-106 on the correct course to
disengage. The F-106 could actually be fully computer-flown during
most of its mission, the pilot actually being needed only for takeoff,
landing, or in case something went wrong with the automation.

The F-106A surprised everyone by having a good maneuverability and
showing potential as being an excellent dogfighter. Consequently, an
internal 20-mm M61A1 rotary cannon was fitted internally to some
aircraft under the aegis of project *Sharp Shooter*. The cannon
replaced the Genie nuclear-tipped missiles in the weapons bay.
However, this innovation was not provided for the F-106B two-seater.

The F-106 served mainly in the continental United States, in Alaska,
Iceland, and in Canada, but it did serve for short spells in Germany
and South Korea. Although the F-106 was briefly deployed to Osan AFB
in Korea in March of 1968 to provide air defense during the *Pueblo*
incident, the Delta Dart never saw combat.

>From 1972 onwards, the McDonnell Douglas F-15 Eagle gradually began to
replace the Delta Dart in ADC squadrons. As they were removed from
Air Force service, they were passed along to the Air National Guard,
serving with ANG squadrons in California, Florida, Massachusetts,
Michigan, Montana, and New Jersey. The last Delta Dart-equipped Air
Force squadron, the 119th FIS based at Atlantic City, New Jersey flew
its final alert duty on July 7, 1988. The ANG units continued to fly
the last few Delta Darts for a few months longer after the USAF had
relinquished the type.

In March of 1982, F-106A serial number 59-0123 was transferred to
NASA's Langley Memorial Aeronautical Laboratory to serve as a spare
for NASA's NF-106B #816 (ex-USAF serial number 57-2516).

During its long service life, the F-106A had the distinction of
recording the lowest single-engined aircraft accident record in USAF
history.

As F-106As were withdrawn from active duty, they were ferried out to
Davis-Monthan AFB in Arizona where they were placed in storage.
In 1986, a contract was awarded to Flight Systems Inc. to modify 192
surplus Delta Darts stored at Davis-Monthan AFB in Arizona to QF-106A
target drone configuration. This program came to be known as *Pacer
Six*, and the first flight of a converted drone took place in July of
1987. Most of these drones were expended at Tyndall and Holloman AFB
from the year 1989 onward.

Serials of the F-106A:

56-451/467 Convair F-106A Delta Dart
57-229/246 Convair F-106A-CO Delta Dart
57-2453/2455 Convair F-106A-64-CO Delta Dart
57-2456/2460 Convair F-106A-70-CO Delta Dart
57-2461/2465 Convair F-106A-75-CO Delta Dart
57-2466/2477 Convair F-106A-80-CO Delta Dart
57-2478/2485 Convair F-106A-85-CO Delta Dart
57-2486/2506 Convair F-106A-90-CO Delta Dart
58-759/771 Convair F-106A-95-CO Delta Dart
58-772/798 Convair F-106A-100-CO Delta Dart
58-799/899 Cancelled contract (believed for F-106)
59-001/030 Convair F-106A-105-CO Delta Dart
59-031/059 Convair F-106A-110-CO Delta Dart
59-060/086 Convair F-106A-120-CO Delta Dart
59-087/111 Convair F-106A-125-CO Delta Dart
59-112/135 Convair F-106A-130-CO Delta Dart
59-136/148 Convair F-106A-135-CO Delta Dart

Specification of F-106A:

One Pratt & Whitney J75-P-17 turbojet, 17,200 lb.s.t. dry and 24,500
lb.s.t with afterburning. Maximum speed: 1525 mph at 40,000 feet
(Mach 2.31), 1327 mph at 35,000 feet. Landing speed was 173 mph
Initial climb rate was 42,800 feet per minute. Service ceiling was
57,000 feet. Normal range was 575 miles. Maximum range with maximum
external fuel was 1809 miles. Weights were 23,646 pounds empty,
38,700 pounds combat weight, 35,500 pounds gross, and 41,831 pounds
maximum takeoff. Dimensions: wingspan 38 feet 3 1/2 inches, length 70
feet 8 3/4 inches, height 20 feet 3 1/4 inches, wing area 697.8 square
feet. Maximum fuel load was 1440 US gallons. Armament consisted of
one Douglas MB-1 (AIR-2A or 2B) Genie unguided missile with a nuclear
warhead and four Hughes GAR-3 or GAR-4 (later redesignated AIM-4E and
AIM-4G respectively) radar or infrared-homing missiles. All these
missiles were housed within the internal weapons bay. In later
installations, a single 20-mm M61A1 rotary cannon replaced the Genie
nuclear-tipped missile in the internal weapons bay.

Sources:

The Illustrated Encyclopedia of Aircraft Armament, Bill Gunston,
Orion, 1988.

United States Military Aircraft Since 1909, Gordon Swanborough and
Peter M. Bowers, Smithsonian, 1989.

The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.

Fighters of the United States Air Force, Robert F. Dorr and
David Donald, Temple Press Aerospace, 1990.

American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday,
1982.

Post-World War II Fighters, 1945-1973, Marcelle Size Knaack,
Office of Air Force History, 1986.

The World Guide to Combat Planes, William Green, MacDonald, London, 1966

The World's Fighting Planes, William Green, Doubleday, 1964.

The Aircraft of the World, William Green and Gerald Pollinger, Doubleday,
1965.

General Dynamics Aircraft and their Predecessors, John Wegg, Naval
Institute Press, Naval Institute Press, 1990.

Joe Baugher AT&T Bell Laboratories
2000 North Naperville Road Naperville, Illinois 60566-7033