Douglas X-3 Stiletto

https://en.wikipedia.org/wiki/Douglas_X-3_Stiletto

The Douglas X-3 Stiletto was a 1950s United States experimental jet aircraft
with a slender fuselage and a long tapered nose, manufactured by the Douglas
Aircraft Company. Its primary mission was to investigate the design features of
an aircraft suitable for sustained supersonic speeds, which included the first
use of titanium in major airframe components. Douglas designed the X-3 with the
goal of a maximum speed of approximately 2,000 m.p.h, but it was, however,
seriously underpowered for this purpose and could not even exceed Mach 1 in
level flight. Although the research aircraft was a disappointment, Lockheed
designers used data from the X-3 tests for the Lockheed F-104 Starfighter which
used a similar trapezoidal wing design in a successful Mach 2 fighter.

The Douglas X-3 Stiletto was the sleekest of the early experimental aircraft,
but its research accomplishments were not those originally planned. It was
originally intended for advanced Mach 2 turbojet propulsion testing, but it fell
largely into the category of configuration explorers, as its performance (due to
inadequate engines) never met its original performance goals. The goal of the
aircraft was ambitious—it was to take off from the ground under its own power,
climb to high altitude, maintain a sustained cruise speed of Mach 2, then land
under its own power. The aircraft was also to test the feasibility of
low-aspect-ratio wings, and the large-scale use of titanium in aircraft
structures. The design of the Douglas X-3 Stiletto is the subject of U.S. Design
Patent #172,588 granted on July 13, 1954 to Frank N. Fleming and Harold T.
Luskin and assigned to the Douglas Aircraft Company, Inc.

The X-3 featured an unusual slender, streamlined shape having a very long,
gently-tapered nose and small trapezoidal wings. The aim was to create the
thinnest and most slender shape possible in order to achieve low drag at
supersonic speeds. The extended nose was to allow for the provision of test
equipment while the semi-buried cockpit and windscreen were designed to
alleviate the effects of "thermal thicket" conditions. The low aspect ratio,
unswept wings were designed for high speed and later the Lockheed design team
used data from the X-3 tests for the similar F-104 Starfighter wing design. Due
to both engine and airframe problems, the partially completed second aircraft
was cancelled, and its components were used for spare parts.


Role
Experimental

Manufacturer
Douglas

Designer
Schuyler Kleinhans, Baily Oswald and Francis Clauser

First flight
15 October 1952

Retired
23 May 1956

Status
Preserved at National Museum of the United States Air Force

Primary users
United States Air Force
NACA

Number built
1

The first X-3 "hop" was made on 15 October 1952, by Douglas test pilot Bill
Bridgeman. During a high-speed taxi test, Bridgeman lifted the X-3 off the
ground and flew it about 1 mi (1.6 km) before settling back onto the lakebed.
The official first flight was made by Bridgeman on 20 October, and lasted about
20 minutes. He made a total of 26 flights (counting the hop) by the end of the
Douglas tests in December 1953. These showed that the X-3 was severely
under-powered and difficult to control. Its takeoff speed was an unusually high
260 kn (482 km/h). More seriously, the X-3 did not approach its planned top
speed. Its first supersonic flight required that the airplane make a 15° dive to
reach Mach 1.1. The X-3's fastest flight, made on 28 July 1953, reached Mach
1.208 in a 30° dive. A plan to re-engine the X-3 with rocket motors was
considered but eventually dropped.

With the completion of the contractor test program in December 1953, the X-3 was
delivered to the United States Air Force. The poor performance of the X-3 meant
only an abbreviated program would be made, to gain experience with low aspect
ratio wings. Lieutenant Colonel Frank Everest and Major Chuck Yeager each made
three flights. Although flown by Air Force pilots, these were counted as NACA
flights. With the last flight by Yeager in July 1954, NACA made plans for a
limited series of research flights with the X-3. The initial flights looked at
longitudinal stability and control, wing and tail loads, and pressure
distribution.

NACA pilot Joseph A. Walker made his pilot checkout flight in the X-3 on 23
August 1954, then conducted eight research flights in September and October. By
late October, the research program was expanded to include lateral and
directional stability tests. In these tests, the X-3 was abruptly rolled at
transonic and supersonic speeds, with the rudder kept centered. Despite its
shortcomings, the X-3 was ideal for these tests. The mass of its engines, fuel
and structure was concentrated in its long, narrow fuselage, while its wings
were short and stubby. As a result, the X-3 was "loaded" along its fuselage,
rather than its wings. This was typical of the fighter aircraft then in
development or testing.

For the X-3, the roll coupling flight was the high point of its history. The
aircraft was grounded for nearly a year after the flight, and never again
explored its roll stability and control boundaries. Walker made another ten
flights between 20 September 1955 and the last on 23 May 1956. The aircraft was
subsequently retired to the U.S. Air Force Museum. Although the X-3 never met
its intention of providing aerodynamic data in Mach 2 cruise, its short service
was of value. It showed the dangers of roll inertia coupling, and provided early
flight test data on the phenomenon. Its small, highly loaded unswept wing was
used in the Lockheed F-104 Starfighter, and it was one of the first aircraft to
use titanium. Finally, the X-3's very high takeoff and landing speeds required
improvements in tire technology.

Specifications (X-3)

General characteristics
Crew: 1
Length: 66 ft 9 in (20.35 m)
Wingspan: 22 ft 8 in (6.91 m)
Height: 12 ft 6 in (3.82 m)
Wing area: 166.5 sq ft (15.47 m2)
Aspect ratio: 3
Empty weight: 14,345 lb (6,507 kg)
Gross weight: 20,800 lb (9,435 kg)
Max takeoff weight: 22,400 lb (10,160 kg)
Powerplant: 2 × Westinghouse XJ34-WE-17 afterburning turbojets, 3,370 lbf (15.0
kN) thrust each dry, 4,900 lbf (22 kN) with afterburner

Performance
Maximum speed: 613.5 kn (706 mph; 1,136 km/h) at 20,000 ft (6,100 m)
Maximum speed: Mach 0.987
Range: 432 nmi (497 mi; 800 km)
Endurance: 1 hour at 512.7 kn (590.0 mph; 949.5 km/h)at 30,000 ft (9,100 m)
Service ceiling: 38,000 ft (12,000 m) absolute
Rate of climb: 19,000 ft/min (97 m/s)
Wing loading: 124.9 lb/sq ft (610 kg/m2)
Thrust/weight: 0.4762 lbf/lb (0.004670 kN/kg)




*

"Stormin' Norman" wrote in message
...

On 12 Jun 2018 06:30:08 -0700, Miloch
wrote:

Although the research aircraft was a disappointment, Lockheed designers
used data from the X-3 tests for the Lockheed F-104 Starfighter which
used a similar trapezoidal wing design in a successful Mach 2 fighter.

A great example of how we learn more from our failures.

What, the X-3 or the F-104? https://tinyurl.com/y7h2vuq2

https://en.wikipedia.org/wiki/Lockhe...#Safety_record

https://m.dailykos.com/stories/2015/...04-Starfighter

In article ,
"Byker" wrote:

"Stormin' Norman" wrote in message
...

On 12 Jun 2018 06:30:08 -0700, Miloch
wrote:

Although the research aircraft was a disappointment, Lockheed designers
used data from the X-3 tests for the Lockheed F-104 Starfighter which
used a similar trapezoidal wing design in a successful Mach 2 fighter.

A great example of how we learn more from our failures.

What, the X-3 or the F-104? https://tinyurl.com/y7h2vuq2

https://en.wikipedia.org/wiki/Lockhe...#Safety_record

https://m.dailykos.com/stories/2015/...ight-stuff-F-1
04-Starfighter
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The Lockheed F-104 was not a too bad design for what it was conceived
High altitude bomber interception. The Spanish Ejercito del Aire that
used it in this function was satisfied. But using it as a low-altitude
fighter bomber was criminal stupidity for the BundesLuftwaffe. Political
reasons have motivated the choice and German pilots paid it with their
lives. A very bad joke at the time in Germany was "What is an optimist?
A Starfighter pilot who stop smoking so he will not die from cancer".
The problems for the Starfighters of BundesLuftwaffe were several : a
lot of new pilots with very little flying experience, a lot of new
maintenance men without experience of complex fighters, a lack of a
sufficient number of older experienced men (no flights between 1945 and
1956) to help the new one, an aircraft with an ejection seat conceived
for high altitude flight and totally inadapted to low altitude high
speed flight (corrected later). You add that the aircraft was used in a
role it was not conceived for, and you understand why the Starfighter
was known in Germany as the widow-maker.