the reports about Sound barrier in Gas dynamic lecture.

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Sound Barrier
Student Name: Rawa Abdullah Taha
Class: two – Group A
Course Title: Gas Dynamics
Department: Mechanic and Mechatronics
College of Engineering
Salahaddin University - Erbil
Academic Year 2019 – 2020

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ABSTRACT
The sound barrier is an important subject of motion and mechanic. The
sound barrier is created because of the high speed. For example, when a
plane travels at a high speed, the sound speed decreases. We can see it
with our own eyes that seen with white clouds around the plane . it ould
be the barrier that created because of his high speed. So that we can say
as a illumination for understand better, The sound barrier or sonic
barrier is the sudden upsurge in aerodynamic drag and other undesirable
effects experienced by an aircraft or other object when it approaches
the speed of sound. While aircraft first began to be able to reach close to
the speed of sound, these effects were seen as constituting a barrier
making faster speeds very difficult or impossible, The term sound
barrier is tranquil sometimes used today to refer to aircraft
reaching supersonic flight.

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TABLE OF CONTENTS
Abstract 2
Table of Contents 3
Introduction 4
Introduction 5
Introduction 6
Introduction 7
Introduction 8
Conclusion 9
References 10

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INTRODUCTION
Several public whips such as the bullwhip or stockwhip are able to move
faster than sound: the tip of the whip surpasses
this speed and causes a sharp crack-literally
a sonic boom. Firearms made after the 19th
century generally have a supersonic muzzle
velocity.
The sound barrier may have been first breached
by living beings some 150 million years ago.
Some paleobiologists report that, based
on computer models of
their biomechanical capabilities, certain long-
tailed dinosaurs such
as Brontosaurus, Apatosaurus,
and Diplodocus may have been able to flick
their tails at supersonic speeds,
creating a cracking sound.
This finding is theoretical and disputed by
others in the field.Meteors entering the
Earth's atmosphere usually, if not always,
descend faster than sound.
Figure(2): Apatosaurus
Early problems: The gradient of the propeller on many early aircraft may
reach supersonic speeds, producing a noticeable buzz that differentiates
such aircraft. This is undesirable, as the transonic air movement creates
disruptive shock waves and turbulence. It is due to these effects that
propellers are known to suffer from dramatically decreased performance
as they approach the speed of sound. It is easy to demonstrate that the
power required to improve performance is so great that the weight of the
required engine grows faster than the power output of the propeller can
compensate. This problem was one that led to early research into jet
Figure(1) :Stockwhip

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engines, notably by Frank Whittle in England and Hans von Ohain in
Germany, who were led to their research specifically in order to avoid
these problems in high-speed flight. Nevertheless, propeller
aircraft were able to approach the critical Mach number in a dive.
Unfortunately, doing so led to numerous crashes for a variety of reasons.
Most infamously, in the Mitsubishi Zero, pilots flew at full power into the
terrain because the rapidly increasing powers acting on the control
surfaces of their aircraft overpowered them. In this case, several attempts
to fix it only made the problem worse. Likewise, the flexing caused by
the low torsional stiffness of the Supermarine Spitfire's wings caused
them, in turn, to counteract aileron control inputs, leading to a condition
known as control reversal. This was solved in later models with changes
to the wing. Worse still, a particularly dangerous interaction of the
airflow between the wings and tail surfaces of diving Lockheed P-38
Lightnings made "pulling out" of dives difficult; however, the problem
was later solved by the addition of a "dive flap" that upset the airflow
under these circumstances. Flutter due to the formation of shock
waves on curved surfaces was another major problem, which led most
famously to the breakup of de Havilland Swallow and death of its
pilot, Geoffrey de Havilland, Jr. on 27 September 1946. A similar
problem is thought to have been the cause of the 1943 crash of the BI-
1 rocket aircraft in the Soviet Union.
38-Lockhead P):Figure(3
gLightin
All of these effects, while unrelated in most ways, led to the concept of a
"barrier" making it difficult for an aircraft to exceed the speed of
sound. Erroneous news reports caused most people to envision the sound
barrier as a physical "wall", which supersonic aircraft needed to "break"

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with a sharp needle nose on the front of the fuselage. Rocketry and
artillery experts' products routinely exceeded Mach 1, but aircraft
designers and aerodynamic engineers during and after World War II
discussed Mach 0.7 as a limit dangerous to exceed.
Early claims: During WWII and immediately thereafter, a number of
claims were made that the sound barrier had been broken in a dive. The
mainstream of these purported events can be dismissed as instrumentation
errors. The typical airspeed indicator (ASI) uses air pressure differences
between two or more points on the aircraft, typically near the nose and at
the side of the fuselage, to produce a speed figure. At high speed, the
various compression effects that lead to the sound barrier also cause the
ASI to go non-linear and produce
inaccurately high or low readings,
depending on the specifics of the
installation. This effect became known as
"Mach jump" Before the introduction
of Mach meters, correct measurements of
supersonic speeds could only be made
externally, normally using ground-based
instruments. Many claims of supersonic
speeds were found to be far below this
speed when measured in this fashion.
Figure(4)
Haroldthat Lts.utteringissued a press releaseRepublic AviationIn 1942,
and Roger Dyar had exceeded the speed of sound duringE. Comstock
. It is widely agreed that this was due)tThunderbol47-P(test dives in the
51-North American Ptheto inaccurate ASI readings. In similar tests,
, a higher performance aircraft, demonstrated limits at MachMustang
0.85, with every flight over M0.84 causing
.nto be damaged by vibratiothe aircraft
Thunderbolt47-Figure(5):P

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Breaking the sound barrier: In 1942, the United Kingdom's Ministry of
Aviation began a top-secret project with Miles Aircraft to develop the
world's first aircraft capable of breaking the sound barrier. The project
resulted in the progress of the prototype Miles M.52 turbojet powered
aircraft, which was designed to reach 1,000 mph (417 m/s; 1,600 km/h)
(over twice the existing speed record) in level flight, and to climb to an
altitude of 36,000 ft (11 km) in 1 minute 30 sec.
A huge number of advanced features were incorporated into the resulting
M.52 design, many of which hint at a detailed knowledge of supersonic
aerodynamic. In particular, the design featured a conical nose and sharp
wing leading edges, as it was known that round-nosed projectiles could
not be stabilised at supersonic speeds. The
design used very thin wings of biconvex
section proposed by Jacob for low drag.
The wing tips were "clipped" to keep them
clear of the conical shock wave generated
by the nose of the aircraft. The fuselage
had the minimum cross-section allowable
around the centrifugal engine with fuel
tanks in a saddle over the top.
Figure(6):Miles M.52
The first ''official'' aircraft to break the sound barrier: The British Air
Ministry contracted an agreement with the United States to exchange all
its high-speed research, data and designs and Bell Aircraft company was
given access to the drawings and research on the M.52, but the U.S.
reneged on the agreement and no data was forthcoming in return. Bell's
supersonic design was still using a conventional tail and they were
Figure(7)

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battling the problem of control, They utilized the information to initiate
work on the Bell X-1. The final version of the Bell X-1 was very similar
in design to the original Miles M.52 version. Also featuring the all-
moving tail, the XS-1 was later known as the X-1. It was in the X-1
that Chuck Yeager was credited with being the first person to break the
sound barrier in level flight on October 14, 1947, flying at an altitude of
45,000 ft (13.7 km). George Welch made a plausible but officially
unverified claim to have broken the sound barrier on 1 October 1947.
Breaking the sound barrier in a land vehicle: On January 12, 1948, a
Northrop unmanned rocket sled became the first land vehicle to break the
sound barrier. At a military test facility at Muroc Air Force
Base (now Edwards AFB), California, it reached a peak speed of
1,019 mph (1,640 km/h) before jumping the rails.
On October 15, 1997, in a vehicle designed and built by a team led
by Richard Noble, Royal Air Force pilot Andy Green became the first
person to break the sound barrier in a land vehicle in compliance
with Fédération Internationale de l'Automobile rules. The vehicle, called
the Thrust SSC ("Super Sonic Car"), captured the record 50 years and one
day after Yeager's first supersonic flight.
Figure(8):Thrust SSC

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CONCLUSION
During the article I spoke briefly about the sound Barrier and
brought up several different examples and described it in
general in its history of sound barrier . I get that information
that we can creat oun sound barrier when you using the whips
with high speed and you see the reaction of it ,that made a white
cloud around this things anythings that going faster than sound
-s the science of higha,speed it might be created the sound barrier
speed flight became more widely understood, a number of changes led to
erstanding that the "sound barrier" is easily penetrated,the eventual und
with the right conditions. Among these changes were the introduction of
increasing-, and engines of everarea rule, theswept wingsthin
aircraft could routinely break thebattleperformance. By the 1950s, many
sound barrier in level flight, although they often suffered from control
. Modern aircraft can transitMach tuckh asproblems when doing so, suc
.sthe "barrier" without control problem

10. 10
REFERENCES
.7Nemiroff, R.; Bonnell, J., eds. (19 August 200]1[
John Derry: The Story ofRivas, Brian, and Bullen, Annie (1996),]2[
., William KimberBritain's First Supersonic Pilot
..ilot)PnknownUheT(Mutke, Hans Guido.]3[
,)Enthusiatr(Aird P. "Saga of the Rocket ShipsHallion, Dr. Richa]4[
February 1978. Bromley, Kent, UK: Pilot Press Ltd.,–November 1977
.1977
,. New York: Farrar, Straus and GirouxfThe Right Stuflfe. Tom.Wo]5[