jfb@ihlpm.att.com (Joseph F Baugher) (12/20/90)
From: jfb@ihlpm.att.com (Joseph F Baugher)
A couple of months back, someone on the net asked about the airplanes in the
X series. I got interested and started digging through some references.
Here's what I came up with. I hope someone finds this useful or at least
interesting. Enjoy!
The X-series was introduced in 1948, at the same time that the F fighter
series was introduced. It was intended to designate aircraft acquired by
the military solely to gather experimental data in the exploration of new
technologies. By now the X-series has reached the 31st entry. Here they
are!
Bell X-1 Formerly XS-1. Air-launched supersonic
rocket-powered research aircraft
XS-1 was first aircraft to exceed the speed
of sound.
X-1A reached speed of Mach 2.5.
Total of six built.
Bell X-2 Formerly XS-2. Air-launched supersonic
rocket-powered research aircraft. Two built.
First aircraft to attain a speed of 2000 mph.
Douglas X-3 Stiletto Single-seat jet-powered high speed research
aircraft. Designed to achieve Mach 2 speeds.
Two Westinghouse XJ34-WE-17 turbojets. Long
needle nose housing most of the test
instrumentation. Pressurized cockpit with
downward ejector seat (which was also an
electrically-operated lift for pilot entry and
exit). Short and stubby wings of thin cross
section. Titanium used in various critical
airframe components. Disappointing performance
due to low thrust of engines. Found to be
only marginally supersonic, even in a dive.
706 mph at 20,000 ft in level flight. USAF
cancelled the program after only six flights.
NACA made a few more flights after USAF
cancellation, and the sole X-3 built was
eventually consigned to the Air Force Museum.
Northrop X-4 Formerly designated XS-4. Tailless research
aircraft. Two Westinghouse J-30-WE-17
turbojets. Two built.
Bell X-5 Formerly designated XS-5. Variable sweep
research aircraft. Based on Messerschmitt
P1101 prototype which had been partially
completed at the end of World War 2. Two
built.
Convair X-6 Projected nuclear-powered research version of
B-36.
Lockheed X-7A High-altitude unpiloted ramjet test vehicle.
Aerojet X-8A Aerobee Upper atmosphere unpiloted test vehicle. Over
100 built.
Bell X-9 Shrike Rocket test vehicle for GAM-63 Rascal air to
surface missile.
North American X-10 Tail-first test vehicles for SM-64 Navajo
cruise missile.
Convair X-11 Designation given for test vehicle for SM-65
Atlas intercontinental ballistic missile.
Convair X-12 Designation given for test vehicle for SM-65
Atlas intercontinental ballistic missile.
Ryan X-13 Vertijet Experimental vertical take off jet aircraft.
Delta wing. Took off and landed vertically from
a trolley. Only two built.
Bell X-14 Jet-deflection STOL test aircraft.
North American X-15A Single-seat, rocket-powered high speed and
high altitude research aircraft. One 57,000
lb. st. Thiokol XLR 99 liquid-fueled rocket
engine. Launched from pylon under the wing
of a B-52, lands on a pair of retractable
skids under the rear fuselage. Retractable
nosewheel under forward fuselage. Reached
speeds of 4104 mph and altitudes of 354,200
feet. Three built. X-15A-2 is modification
of second X-15A with longer fuselage,
redesigned windshield, and provision for two
large external tanks carrying additional fuel.
Bell X-16 Twin-jet high-altitude research aircraft.
Was actually a cover for a CIA project to
develop a spyplane. Project was cancelled in
favor of Lockheed U-2 before any example could
be completed. Two J57-PW-37A turbojets.
Lockheed X-17 Unpiloted nose-cone entry research vehicle.
26 built.
Hiller X-18 Tilt-wing VTOL research aircraft.
Curtiss-Wright X-19A Twin-engined V/STOL experimental aircraft
Two Lycoming T55 shaft turbines driving four
tilt rotors, one mounted on each "winglet"
Rotors orient vertically for takeoff, then
tilt horizontally for conventional flight.
460 mph at 20,000 ft.
Boeing X-20 Dynasoar Rocket-launched orbital glider. Ten ordered.
Project cancelled before any could be delivered.
Northrop X-21A Five-seat laminar-flow research aircraft.
It is an extensively-modified Douglas WB-66D
Destroyer with 25 degree swept wings of much
greater area with slots and metering holes
to suck the boundary layer air from the wing
surface through a pumping system. Two 9490 lb.
st. General Electric XJ-79-GE-13 70 turbojets in
pods attached to the rear fuselage. Crew of
pilot, two flight engineers in front cockpit,
and two flight engineers in center fuselage
beneath the wing. Two built. 528 mph
at 40,000 ft. Laminar flow wing did provide
for increased range, but the maintenance
difficulties associated with need to keep
wing slots spotlessly clean proved too costly
for any practical application.
Bell X-22A Four-engined V/STOL experimental aircraft.
Four General Electric YT-58 turbines powering
dual tandem ducted props. Ducts tilt
vertical for VTOL, horizontal for conventional
flight. Ducts have lifting surfaces when
horizontal for forward flight. 345 mph.
Martin X-23 Unpiloted lifting body reentry test vehicle.
Four built.
Martin X-24 SV-5P piloted lifting body prototype. One
XLR22-RM-13 rocket motor.
Bensen X-25 X-25A was gyrocopter, X-25B was gyro-glider,
and X-25 was discretionary descent vehicle for
USAF evaluation.
Schweizer X-26 X-26A was designation given to four Schweizer
SGS 2-32 sailplanes acquired by US Navy for
tests. X-26B was powered version adapted by
Lockheed for quiet aircraft research.
Lockheed X-27 Designation reserved for proposed USAF
evaluation of CL-1200 Lancer adaptation of
F-104 Starfighter. Project cancelled.
Pereira X-28 Home-built seaplane acquired for US Navy
evaluation. One Continental C90 engine.
Grumman X-29A Single-seat research aircraft to study swept-
forward wing technology. Fly-by-wire control
system, variable-camber trailing edge, composite
material construction. One 16,000 lb. st. GE
F404-GE-400 turbofan. Mach 1.87 (1230 mph) at
altitude. Two built.
X-30 National Aerospace Plane (NASP) testbed project.
Contractor not yet selected.
Rockwell/MBB X-31A Joint German/American fighter maneuverability
demonstration aircraft. One 10,600 lb. st.
GE F404-GE-400 turbofan. Cranked delta wing,
canard surfaces, vector thrusting, and fly-by-
wire control systems. 598 mph at 35,000 ft.
Sources:
Various issues of Aviation Week
The Observer's Book of Aircraft, William Green.
United States Military Aircraft Since 1909, Gordon Swanborough and
Peter Bowers.
Joe Baugher *************************************
AT&T Bell Laboratories * "Callahan, I outa bust your ass *
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ihlpm!jfb
jfb200@cbnewsd.att.com
Who, me? Speak for AT&T? Surely you jest!