space shuttles and its advancements seminar report

Space Shuttles and its Advancements

Dept. of Mechanical Engg. MESCE Kuttippuram

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INTRODUCTION

The successful explortion of space requires a system that will

reliably transport payloads into space and return back to earth; without

subjecting them an uncomfortable or hazardous environment. In other

words, the space crafts and its pay loads have to be recovered safely

into the earth. The space shuttle used at older times were not re-usable.

So NASA invented re-usable space shuttle that could launch like a

rocket but deliver and land like an aeroplane. Now NASA is planning

to launch a series of air-breathing planes that would replace the space

shuttle.



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A BRIEF HISTORY OF THE SPACE SHUTTLE

Near the end of the Apollo space program, NASA officials

were looking at the future of the American space program. At that

time, the rockets used to place astronauts and equipment in outer space

was one-shot disposable rockets. What they needed was a reliable, but

less expensive, rocket, perhaps one that was reusable. The idea of a

reusable "space shuttle" that could launch like a rocket but deliver and

land like an airplane was appealing and would be a great technical

achievement.

Photo courtesy NASA Liftoff of the space shuttle



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NASA began design, cost and engineering studies on a space

shuttle. Many aerospace companies also explored the concepts. In

1972 NASA announced that it would develop a reusable space shuttle

or space transportation programme (STS).NASA decided that the

shuttle would consist of an orbiter attached to solid rocket boosters

and an external fuel tank because this design was considered safer and

more cost effective.

At that time, spacecraft used ablative heat shields that would

burn away as the spacecraft re-entered the Earth's atmosphere.

However, to be reusable, a different strategy would have to be used.

The designers of the space shuttle came up with an idea to cover the

space shuttle with many insulating ceramic tiles that could absorb the

heat of re-entry without harming the astronauts.

Finally, after many years of construction and testing (i.e.

orbiter, main engines, external fuel tank, solid rocket boosters), the

shuttle was ready to fly. Four shuttles were made (Columbia,

Discovery, Atlantis, Challenger). The first flight was in 1981 with

the space shuttle Columbia, piloted by astronauts John Young and

Robert Crippen. Columbia performed well and the other shuttles

soon made several successful flights.

The space shuttle consists of the following major components:

Two solid rocket boosters (SRB) - critical for the launch

External fuel tank (ET) - carries fuel for the launch

Orbiter - carries astronauts and payload



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THE SPACE SHUTTLE MISSION

A typical shuttle mission lasts seven to eight days, but can

extend to as much as 14 days depending upon the objectives of the

mission.

A typical shuttle mission is as follows:

1. Getting into orbit

Launch – the shuttle lifts off the launching pad.

Ascent.

Orbital maneuvering burn.

2. Orbit-life in space.

3. Re-entry.

4. Landing.

The difference between space shuttle and hypersonic planes is

mainly in the first function that is getting into orbit. We will study

only about the first function of the space shuttle.

1. GETTING INTO ORBIT

To lift the 4.5 million pound (2.05 million kg) shuttle from

the pad to orbit (115 to 400 miles/185 to 643 km) above the Earth, the

shuttle uses the following components:

Two solid rocket boosters (SRB)

Three main engines of the orbiter

The external fuel tank (ET)

Orbital maneuvering system (OMS) on the orbiter

Let's look at these components closely.



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Solid rocket boosters

The SRBs are solid rockets that provide most of the main

force or thrust (71 percent) needed to lift the space shuttle off the

launch pad. In addition, the SRBssupport the entire weight of the

space shuttle orbiter and fuel tank on the launchad. Each SRB has the

following dimensions.

Height - approximately 150 ft (46 m)

Diameter - 12 ft (3.7 m)

Weight:

o Empty - 192,000 lb (87,090 kg)

o Full - 1,300,000 lb(589,670 kg)

Thrust - 2.65 million lb (11.7

million N wing dimensions,

parameters and parts:

Because the SRBs are

solid rocket engines, once they

are ignited, they cannot be shut

down. Therefore, they are the

last component to light at launch.

Main engines

The orbiter has three main engines located in the aft (back)

fuselage (body of the spacecraft). Each engine is 14 feet (4.3 m) long,

7.5 feet (2. 3 m) in diameter at its widest point (the nozzle)

Photo courtesy NASA

One of the space shuttle's main

engines



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The main engines provide the

remainder of the thrust (29 percent) to lift

the shuttle off the pad and into orbit.

The engines burn liquid hydrogen

and liquid oxygen, which are stored in the

external tank(ET), at a ratio of 6:1. They

draw liquid hydrogen and oxygen from the ET at an amazing rate

equivalent to emptying a family swimming pool every 10 seconds!

The fuel is partially the burned in a pre-chamber to produce high

pressure, hot gases that drive fuel pumps. The fuel is then fully burned

in the main chamber and the exhaust gases (water vapor) leave the

nozzle at approximately 6,000 mph (10,000 km/h). Each engine can

generate between 375,000 and 470,000 lb (1,668,083 to 2,090,664 N)

of thrust; the rate of thrust can be controlled from 65 percent to 109

percent maximum thrust. The engines are mounted on round bearings

that control the direction of the exhaust, which controls the forward

direction of the rocket.

External fuel tank

As mentioned above, the fuel for the main engines is stored in

the ET. The ET is 158 ft (48 m) long and has a diameter of 27.6 ft (8.4

m). When empty, the ET weighs 66,000 lb (30,000 kg). It holds about

1.6 million lb (719,000 kg) of propellant with a total volume of about

526,000 gallons (2 million liters).

Photo courtesy NASA



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The ET is made of aluminum and aluminum composite

materials. It has two separate tanks inside, the forward tank for

oxygen and the aft tank for hydrogen, separated by an intertank

region. Each tank has baffles to dampen the motion of fluid inside.

Fluid flows from each tank through a 17 in. (43 cm) diameter feed line

out of the ET through an umbilical line into the shuttle's main engines.

Through these lines, oxygen can flow at a maximum rate of 17,600

gallons/min (66,600 l/min) and hydrogen can flow at a maximum rate

of 47,400 gallons/min (179,000 l/min). During the first few shuttle

missions, the ET was painted white, but this was stopped to reduce the

weight.

Orbital maneuvering systems

The two orbital maneuvering systems' (OMS) engines are

located in pods on the aft section of the orbiter, one on either side of

the tail. These engines are used to place the shuttle into final orbit, to

change the shuttle's position from one orbit to another, and to slow the

shuttle down for re-entry.



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The OMS engines burn monomethyl hydrazine fuel

(CH3NHNH2) and nitrogen tetroxide oxidizer (N2O4). Interestingly,

when these two substances come in contact, they ignite and burn

automatically (i.e., no spark required) in the absence of oxygen. The

fuel and oxidizer are kept in separate tanks, each pressurized by

helium. The helium is used to push the fluids through the fuel lines

(i.e., no mechanical pump required). In each fuel line, there are two

spring-loaded solenoid valves that close the lines. Pressurized

nitrogen gas, from a small tank located near the engine, is used to

open the valves and allow the fuel and oxidizer to flow into the

combustion chamber of the engine. When the engines are shut off, the

nitrogen goes from the valves into the fuel lines momentarily to flush

the lines of any remaining fuel and oxidizer; this purge of the line

prevents any unwanted explosions. During a single flight, there is

enough nitrogen to open the valves and purge the lines 10 times.

Either one or both of the OMS engines can fire, depending

upon the orbital maneuver. Each OMS engine can produce 6,000 lb

(26,400 N) of thrust. The OMS engines together can accelerate the

shuttle by 2 ft/s2 (0.6 m/s

2). This acceleration can change the shuttle's

velocity by as much as 1,000 ft/s (305 m/s). To place into orbit or to

de-orbit takes about 100-500 ft/s (31-153 m/s) change in velocity.

Orbital adjustments take about 2 ft/s (0.61 m/s) change in velocity.

The engines can start and stop 1,000 times and have a total of 15 h

burn time.



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As the shuttle rests on the pad fully fueled, it weighs about

4.5 million pounds or 2 million kg. The shuttle rests on the SRBs as

pre-launch and final launch preparations are going on through T minus

31 seconds:

1. T minus 31 s - the on-board computers take over the launch

sequence.

2. T minus 6.6 s - the shuttles main engines are ignited one at a

time (0.12 s apart). The engines build up to more than 90 percent

of their maximum thrust.

3. T minus 3 s - shuttle main engines are in lift-off position.

4. T minus 0 s -the SRBs are ignited and the shuttle lifts off the

pad.

5. T plus 20 s - the shuttle rolls right (180 degree roll, 78 degree

pitch).

6. T plus 60 s - shuttle engines are at maximum throttle.

7. T plus 2 min - SRBs separate from the orbiter and fuel tank at

an altitude of 28 miles (45 km). Main engines continue firing.

Parachutes deploy from the SRBs.

SRBs will land in the ocean (about 140 miles (225 km) off the

coast of Florida.

Ships will recover the SRBs and tow them back to Cape

Canaveral for processing and re-use.

1. T plus 7.7 min - main engines throttled down to keep

acceleration below 3g's so that the shuttle does not break

apart.

2. T plus 8.5 min - main engines shut down.

3. T plus 9 min - ET separates from the orbiter. The ET will

burn up upon re-entry.



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4. T plus 10.5 min - OMS engines fire to place you in a low

orbit.

5. T plus 45 min - OMS engines fire again to place you in a

higher, circular orbit (about 250 miles/400 km).

SPACE PLANES AND REPLACEMENT OF SPACE

SHUTTLE

To replace the space shuttle NASA is planning to launch a

series of space planes that named as X series planes. Some X series

planes are given below

The X-37, which will test many space plane technologies,

including re-entry capabilities.

The X-34, a sub orbital vehicle that will test technologies to

reduce cost, time and personnel for space launches.

The X-33, a reusable launch vehicle (RLV) that is a prototype

for a space shuttle replacement.

In this the third one that is X-33 is the one that will replace

the space shuttle in the future. Despite the shuttle's many

accomplishments, the fact remains that it is extremely expensive to

launch into space. Each pound of payload in the shuttle's bay costs

$10,000 to launch. According to NASA, each of the space shuttle's

two solid rocket boosters carries about 1 million pounds (453,592 kg)

of solid propellant. The large external tanks hold another 500,000



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gallons of super cold liquid oxygen and liquid hydrogen. These two

liquids are mixed and burned to form the fuel for the shuttle's three

main rocket engines. The cost of this huge amount of propellant, and

of recovering and replacing the solid rocket boosters for every mission

is extremely expensive. NASA's solution to the problem is the X-33.

The X-33 is a prototype for a unique single-stage-to-orbit

vehicle. Its wedge-like shape is unlike any spacecraft that has

preceded it. At its base, the X-33 is 77 feet (23.5 m) wide, and the

vehicle is 69 feet (21 m) long. The purpose of this design is to allow

the spacecraft to hold all of the needed propellant onboard the ship,

thus eliminating the need for solid rocket boosters. By eliminating the

boosters and the main fuel tank, NASA will trim much of the liftoff

weight that makes space shuttle missions so expensive. Launch costs

for the X-33, or a derivative of the X-33, are expected to be only a

tenth of the cost of launching the space shuttle.

Two more tests will follow, and successful testing could lead

to a more efficient space-access vehicle. NASA officials say that

the scramjet engine would be a major step forward for NASA and

would arguably provide a safer, more flexible, less expensive way to

get people and cargo to space.



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HYPER SONIC PLANES WITH AIR BREATHING

ENGINES

Living in air

The futuristic X-43A prototype looks like a flying surfboard.

It’s thin, has a wingspan of 5 feet (1.5 m), measures 12 ft (3.7 m) long

and 2 ft (0.61 m) thick and weighs 2,800 pounds (1,270 kg). A

working version of the X-43A will be about 200 ft (61 m) in length

but still relatively lightweight, en most unique feature of the X-43A is

its engine.

abling it to carry heavier loads into space. But the most unique feature

of the X-43A is its engine.

Photo courtesy NASA

The dimensions and views of the X-43A



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The best way to understand an X-43A’s air-breathing engine

is to first look at a conventional rocket engine. A typical rocket engine

is propelled by the combustion created when a liquid oxidizer and a

hydrogen fuel are burned in a combustion chamber. These gases create

a high-pressure, high-velocity stream of hot gases. These gases flow

through a nozzle that further accelerates them to speeds of 5,000 to

10,000 mph (8,047 to 16,093 kph) and provides thrust.

The disadvantage of a conventional rocket engine is that it

requires a lot of onboard oxygen. For example, the space shuttle needs

143,000 gallons of liquid oxygen, which weighs 1,359,000 pounds

(616,432 kg). Without the liquid oxygen, the shuttle weighs a mere

165,000 pounds 74,842 kg . NASA has determined that it can easily

drop the weight of a vehicle at launch if they were to take away the

liquid oxidizer, which would quickly drop the weight of the vehicle to

about 3.1 million pounds. That's still a heavy vehicle, but it would

mean a huge reduction in cost of launching a vehicle into orbit.

Solution to this is its air-breathing engine. An air-breathing

engine requires no onboard oxygen. The X-43A will scoop up oxygen

as it flies through the atmosphere. In an Earth-to-orbit mission, the

vehicle would store extra oxygen onboard, but less than what a space

shuttle requires. The scramjet engine is a simple design with no

moving parts. The X-43A craft itself is designed to be a part of the

engine system: The front of the vehicle acts as the intake for the

airflow, and so, if you remove the liquid oxygen, wouldn't the fuel be

unable to combust and provide thrust? You have to think outside the

normal operation of a conventional rocket engine. Instead of using



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liquid oxidizer, an air-breathing rocket, as its name suggests, will take

in air from the atmosphere. It will then combine it with the fuel to

create combustion and provide thrust.

An air-breathing rocket engine, also called a rocket-based,

combined cycle engine, is very similar to a jet engine. In a jet engine,

the compressor sucks in air. The engine then compresses the air,

combines it with a fuel, and burns the product, which expands and

provides thrust. A jet engine can only be used for up to Mach 3 or 4

before its parts will begin to overheat. In a supersonic combustion

ramjet, or scramjet, an air inlet draws in air. The air is slowed and

compressed as the vehicle speeds through the atmosphere. Fuel is

added to the supersonic airflow, where the two mix and burn. Fuels

most likely to be used with the air-breathing rockets include liquid

hydrogen or hydrocarbon fuel

Taking flight

As mentioned before, scramjet-powered aircraft don’t carry

oxygen onboard. That means that they can’t lift off like conventional

spacecraft. The X-43A will require a booster rocket to get it up to a

hypersonic speed, at which point it will be released and sent flying on

its own. This rocket boost is necessary for the scramjet engine to

work.

As efficient as air-breathing rockets are, they can't provide the

thrust for liftoff. For that, there are two options being considered.

NASA may use turbojets or air-augmented rockets to get the vehicle

off the ground. An air-augmented rocket is like a normal rocket

engine, except that when it gets a high enough speed, maybe at Mach



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two or three, it will augment the oxidization of the fuel with air in the

atmosphere, and maybe go up to Mach 10 and then change back to

normal rocket function. These air-augmented rockets are placed in a

duct that capture air, and could boost performance about 15 percent

over conventional rockets. Further out, NASA is developing a plan to

launch the air-breathing rocket vehicle by using magnetic levitation

(maglev) tracks. Using maglev tracks, the vehicle will accelerate to

speeds of up to 600 mph before lifting into the air.

Following liftoff and after the vehicle reaches twice the speed

of sound, the air-augmented rockets would shut off. Propulsion would

then be provided by the air-breathing rocket vehicle, which will inhale

oxygen for about half of the flight to burn fuel. The advantage of this

is it won't have to store as much oxygen on board the spacecraft as

past spacecraft have, thus reducing launch costs. Once the vehicle

reaches 10 times the speed of sound, it will switch back to a

conventional rocket-powered system for a final push into orbit.

Because it will cut the weight of the oxidizer, the vehicle will

be easier to maneuver than current spacecraft. This means that

traveling on an air-breathing rocket-powered vehicle will be safer.

Eventually, the public could be traveling on these vehicles into space

as space tourists.

Two more tests will follow, and successful testing could lead

to a more efficient space-access vehicle. NASA officials say that the

scramjet engine would be a major step forward for NASA and would

arguably provide a safer, more flexible, less expensive way to get

people and cargo to space.



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The Marshall Center and NASA's Glenn research center

Cleveland are planning to design a flight-weight air-breathing rocket

engine in-house for flight demonstration by 2005.

That project will determine if air-breathing rocket engines can

be built light enough for a launch vehicle.

Photo courtesy NASA

Magnetic levitation tracks could one day be used to

launch vehicles into space.



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ADVANTAGES

Reduces launch cost

Vehicle will be easier to maneuver the current spacecraft.

Air-breathing rocket-powered vehicle will be safer



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CONCLUSION

By using air breathing engine we can reduce the launch cost.

Moreover air breathing rocket vehicle safer as compaired to

conventional rocket.



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REFERENCES

1. www.howstuffworks.com

2. www.howspaceshuttleworks.com

3. spacecraft system engineering- Peter Fortescue and John

Stoaark



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ABSTRACT

In its 23 year history, the NASA space shuttle program has

seen exhilarating highs and devastating lows. The fleet has taken

astronauts on dozens of successful missions, resulting in immeasurable

scientific gains. But this success has had a serious cost. In 1986, the

challenger exploded during launch procedures, and on February 1st of

2003, the Columbia broke up during re-entry over Texas.

This seminar report would be covering the following points:-

A BRIEF HISTORY OF THE SPACE SHUTTLE.

THE SPACE SHUTTLE MISSION.

SPACE PLANES AND THE REPLACEMENT OF SPACE

SHUTTLES.

This seminar will be taking a brief look into the latest space

planes namely the “HYPER SONIC PLANES WITH AIR

BREATHING ENGINES” that are being planned to be rolled out by

NASA for space exploration purpose.



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ACKNOWLEDGEMENT

First of all I thank the almighty for providing me with the

strength and courage to present the seminar.

I avail this opportunity to express my sincere gratitude

towards

Dr. T.N. Sathyanesan, head of mechanical engineering department,

for permitting me to conduct the seminar. I also at the outset thank and

express my profound gratitude to my seminar guide Mr. Mohan C.C.

and staff incharge Asst. Prof. Mrs. Jumailath Beevi. D., for their

inspiring assistance, encouragement and useful guidance.

I am also indebted to all the teaching and non- teaching staff

of the department of mechanical engineering for their cooperation and

suggestions, which is the spirit behind this report. Last but not the

least, I wish to express my sincere thanks to all my friends for their

goodwill and constructive ideas.

Aju S.S.



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CONTENTS

1. INTRODUCTION 1

2. A BRIEF HISTORY OF THE SPACE SHUTTLE 2

3. THE SPACE SHUTTLE MISSION 4

4. SPACE PLANES AND REPLACEMENT OF SPACE SHUTTLE 10

5. HYPER SONIC PLANES WITH AIR BREATHING ENGINES 12

6. ADVANTAGES 17

7. CONCLUSION 18

8. REFERENCES 19

space shuttles and its advancements seminar report

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