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Combining the Cruise and Pegasus Missiles for Spy

Micro-Satellite Launching

(Part Two: Primary Sketch)

Mohammad Hassan Ziraksaz*

Islamic Azad University, Science & Research Branch, Tehran, IRAN

Pegasus development to provide a small Air to Space missile for launching

a spy micro-satellite from some countries facing special limitations such as

geographical problems, forbidden flight zones, time spending range and

technical problems to flight in some special zones is the main purpose of

this paper. Studies show that combination of Cruise and Pegasus missiles

is the best solution for overcoming these problems and limitations. This

paper, as the second part of this study, includes the Primary Sketch of the

launcher.

Introduction: Pegasus is an special launcher which

is not applicable in most of the countries

because of using special airplanes,

restriction of launch windows changing,

long time-step launching and flight

restriction over special zones and

boundaries. As it has been reported in part

one (AIAA-2003-5117), the purpose of

combining the Pegasus and Cruise

missiles is not only to overcome the

above mentioned problems but also to

develop its application for micro satellites

launching as well as increasing its

maneuverability.

In this paper two new configurations

are presented and their advantages and

disadvantages are described. The first one

includes a solid rocket and a turbojet

engine as the first and the second stages

of the launcher. In this configuration the

turbojet engine operates after the first

stage burn out (solid one) and the other

original stages of Pegasus operates after

turbojet engine burn out while in the

second sketch both solid rocket and

turbojet engine are restructured to provide

a single stage motor. It means that some

components of turbojet engine and solid

motor are contributed to provide a new

motor as a single stage named

Turbo-Solid stage. Of course using the

solid booster in both configurations could

be studied. Each of these sketches makes

some advantages and disadvantages.

Although the second one is more

complicated than the first one, but in the

first one there are some problems about

starting the turbojet engine and the ratio

of total weight to thrust of the missile.

The second sketch has some

problems on high temperature

performance and the amount of solid

propellant storage and its burning rate,

which affects the hot gases supplement

period while using liquid propellants

causes the hot gases supplement period

increment.

Controllability of combined missile

and its higher maneuverability than

Pegasus missile is one of the most

important advantages of this launcher.

*PhD Student, Faculty member of Aerospace

Engineering Division, Ziraksaz@mstco.net

Copyright © 2008 by the American Institute of

Aeronautics and Astronautics, Inc. All rights

reserved.

AIAA-2008-4975 AIAA-2008-5058

44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit21 - 23 July 2008, Hartford, CT

AIAA 2008-5058

Copyright © 2008 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

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In fact this missile combines the

advantages of both turbojet engine and

solid rocket motor. The second sketch is

more compact and therefore high thrust to

weight ratio. In fact the second sketch is a

turbojet engine which its combustion

chamber is a solid or liquid motor.

Therefore a great amount of high

temperature gases will be flown through

the turbine stages in high velocity.

Mission In most countries the available time

for micro-satellite direct launch and

insertion into LEO is too short to support

the ground launch process. In fact in some

cases the time is too short to initiate the

process. Therefore some of the existed

opportunities must be ignored because of

less available time.

The problem is more highlighted,

considering the fact that the available

time between two sequential opportunities

is short while the distance between the

trajectories is very long. Since moving the

ground launcher is impossible, using air

launchers such as Pegasus is

recommended. Of course there are several

reasons to improve the air launched

missiles rather than the ground launchers

but this is not author concern in this

paper.

On the other hand the short available

time and geographical boundaries'

limitations forces to use the neighbors' air

boundaries. Therefore regardless of all

reasons to use an air to space launch

missile to launch and insert a micro

satellite, bellow items must be considered.

• The launcher must be carried by an

airplane different from the Pegasus

carrier because of its unavailability. it

means that the launcher leaves the

airplane in lower attitude named as

primary position, PP.

• Launcher ability to fly from PP to the

correct launching position, CLP. CLP

is not the real Pegasus second stage

initiating position (RPP) yet.

• Launcher ability to fly from the CLP to

RPP.

Now the new launcher tries to

approach the same destination as

Pegasus', therefore the new launcher must

have two additional stages a new stage

and a corrected one. The new one is the

stage which helps it to fly from the PP to

the CLP and the corrected one is the stage

that must carry the missile from the CLP

to the RPP. In this regard two individual

systems are considered as the first and

second sketches which are briefly

described bellow.

The First Sketch Stages: The first sketch includes 4 stages

each helps the launching process to take

place consequently. The main

characteristics of each stage are presented

bellow:

First Stage:

The first stage of this air to space

missile which is used as an air launch

vehicle is a solid propellant engine. This

stage must be initiated as quickly as the

launcher release from the airplane take

place. The purpose of this stage is to help

the launcher not only to travel far from

the airplane but also providing sufficient

speed to initiate the second stage turbojet

engine and consequently attitude

correction. Then the launcher will travel

from PP to the secondary point, SP.

Second Stage:

The second stage is a turbojet engine.

Using this stage the launcher acts as an

airplane because of its feature. In fact the

launcher is a cruise missile. The launcher

not only has a wing, connected to the

second stage, but also has an internal

intake to use the free stream air because

of its air breathing nature.

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This stage helps the launcher to fly

from SP to the CLP the correct launching

position, where there are some restrictions

such as forbidden flight zones,

geographical boundaries' limitations and

the other problems which make the air

plane flight impossible.

Third and Forth Stages:

The third stage of this new type air to

space launcher is the same as the original

Pegasus missile second stage, but

different in range. In Pegasus missile, the

second stage is used to ascend and fly

from RPP to its 3rd stage initiating

position while in this new type launcher,

the mentioned stage is used to fly from

CLP not from RPP.

Of course the destination is the same.

The forth stage of the combined

launcher is the same as the 3rd stage of

Pegasus'.

The First Sketch Expected

Launching Process This type of launcher will be used for

launching the Spy micro-satellite when

there are some technical flight problems

for approaching the launching zone or the

launching zone is out of the boundaries.

However in both cases there is a specified

point that the aircraft mission will be

terminated. At this point the Air to Space

launcher will be released from the

aircraft. It falls through air and after

providing the safety range its first stage

ignition and the second stage idling start

will be occurred, while its velocity is

subsonic.

Fig.1. Schematic Draft of Combined Air to Space launcher - First Sketch Stages

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This is the beginning of launcher’s

mission. The main purpose of the first

stage is the same as the first stage of

original Pegasus. But there is additional

purpose. This stage will provide the

sufficient condition for cruising process

too. It means that the first stage will be

used not only to accelerate the missile to

take a distance from the released point but

also to provide the best condition to fully

operate the turbojet engine (the second

stage).

Since the aircraft carrier could not

approach the “real launching zone”

therefore, the second stage, which is an

air breathing engine, will be used to

approach the “real launching zone”. The

second stage needs sufficient time to

initiate and start, therefore the turbojet

engine will be started when the first stage

ignition is occurred but it will be in idling

situation.

Proper wings are used for

aerodynamic lifting and maneuvering.

The main wing is connected to the second

stage. The second stage full load

operation will take place after the first

stage burn out. In this case missile is able

to flight as a cruise missile and makes any

required maneuvers to approach the

proper zone, which is the “real launching

zone”. In fact this stage is used not only

to overcome the aircraft disabilities to

flight over special zones such as some

mountains, zones or any restricted and

forbidden zones, but also to fly in

neighbors' boundaries, where the carrier

aircraft can not fly.

After approaching the proper zone,

the third stage ignition, a solid propellant

motor, will take place to ascend the

launcher. Provided impulse and

separation devices help to separate the

turbojet engine. The firing and relevant

case will be separated in the beginning of

missile ascending process.

The forth stage ignition will occur to

ascend the launcher to floating orbit. At

the end of this stage sufficient impulse

will be provided to insert the Spy micro

satellite into the floating circular orbit,

which is near the final orbit. After

burning out the forth stage, the injected

spy micro satellite will try to be installed

properly by correcting its orbit and its

attitude.

The Second Sketch Stages: The first sketch has 3 stages of solid

propellant and a stage of turbojet engine,

which can be a turbofan too. Considering

the mission, fast traveling from PP to SP

and consequently to CLP is the desire.

Since the missile pay load is a micro

satellite therefore the missile weight and

its size is not as much as Pegasus'. But the

missile has to travel very fast while the

second stage, the turbojet engine, may not

be able to provide such a speed because

of its thrust provided range. In this regard

there is another alternative which can help

the system to overcome this feature. This

new type stage which is introduced in this

paper is a combined engine.

This engine not only is a turbojet

engine but also is a solid propellant

motor. In fact some components of

turbojet engine and solid motor are

contributed to provide a new motor as a

single stage motor named as Turbo-Solid

stage. There are three individual sketches

for this new type engine each of them has

some advantages. Since Turbo-Solid is

used in this missile then the first and

second stages are combined to provide a

single stage, therefore the air to space

launcher has three stages.

First Stage Type-A:

The Turbo-Solid engine type-A is a

turbojet engine whose combustion

chamber is replaced by a can annular

combustion chamber. Of course there isn't

any liquid can combustor in this sketch

but each of the cans is a solid propellant

motor with its specific characteristics

such as propellant type, burning rate,

grain, configuration and all requirements.

This sketch is schematically illustrated in

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fig.3. In this type solid propellant cans

provided hot gases in high temperature

without using air because of its nature to

use oxidizer inside. But the compressed

air is used to increase the total mass flow

rate and consequently the provided thrust.

First Stage Type-B:

The Turbo-Solid engine type-B is a

conventional turbojet engine using liquid

fuel to burn in combustion chamber but

there is an extra solid propellant chamber

to charge the liquid fuel combustion

gases. In fact there arte two individual hot

streams one of them is provided by the

turbojet engine while the other one is

provided by the solid propellant chamber.

To avoid the interaction between

liquid fuel hot gases and solid propellant

gases also flow turning into the

combustion chamber, the solid propellant

hot gases injects into the turbine through

different nozzle. To do so, two individual

inlet ports are considered for turbine inlet

nozzle: liquid combustion gases port and

the solid one. This type of Turbo-Solid

engine not only can act as a common

turbo jet engine but also can act as a

mixed liquid and solid propellant motor

since it is a bipropellant: solid and liquid.

First Stage Type-C:

The Turbo-Solid engine type-C is a

different engine. In fact it is a turbojet

engine which does not have compressor

and combustion chamber. Instead it has a

solid chamber which is connected to the

turbine via turbine inlet nozzle directly.

This type is not air breathing and works

with combustion gases provided by the

solid propellant chamber.

The fact that there is not compressor

and combustion chamber any more makes

the engine' weight lower than the previous

types, therefore more solid propellant can

be carried. Considering the fact that

operating the engine, solid fuel will

consume and motor major weight is the

stored solid propellant then the engine

weight will decrease during engine

operation, therefore missile can accelerate

more.

Second Stage:

There is no more changes in first

sketch, then the second stage of the

second sketch is the same as the third

stage of the first sketch, which is the same

as the original Pegasus missile second

stage, but different in range. It means that

the second stage of the first sketch, the

Fig.2. Air to Space Launcher - The First Sketch Expected Launching Process

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Turbo-Solid motor, Type A

Turbo-Solid motor, Type B

Turbo-Solid motor, Type C

Fig.3. Schematic Draft of Combined Air to space launcher - Second Sketch Stages

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third stage of the first sketch and the

second stage of the original Pegasus

missile has three different ranges but the

same destination point.

Third Stage:

The third stage of the combined

launcher (both sketches) is the same as

the third stage of Pegasus.

The Second Sketch Expected

Launching Process This Air to Space launcher is the

modified type of the first sketch to make

the launcher more compact and efficient.

After releasing from the air craft, which is

not the main Pegasus carrier and therefore

is not able to release the launcher in

proper position and attitude, the first

stage, the Turbo-Solid engine, initiates.

The ignition takes place when the

launcher is sufficient far from the aircraft,

PP, for safety reasons. The Turbo-Solid

engine helps launcher to travel from PP to

CLP not to SP.

Since the Turbo-Solid engine is able

to travel far distances very fast, then the

launcher is able to change its trajectories

even to the far trajectories.

Approaching the CLP, first stage

burns out and the second stage, a solid

Propellant stage, initiates to travel from

CLP to Pegasus 3rd stage initiation point.

The other steps are the same as the

Pegasus steps. The relevant schematic

diagram of the Second Sketch Expected

Launching Process is illustrated ion fig.4.

Fig.4. Air to Space Launcher - The Second Sketch Expected Launching Process

References: • Ziraksaz. M. H., Combining the

Cruise and Pegasus Missiles for Spy

Micro-Satellite Launching, 39th AIAA

Joint Propulsion Conference, AIAA-

2003-5117.

• Gordon C. Oates, Aircraft Propulsion

Systems Technology and Design,

AIAA education series, 1989.

• Jack D. Mattingly, Aircraft Engine

Design, AIAA education series, 2002.

• Jack D. Mattingly, Elements of

Propulsion: Gas Turbines and

Rockets, 2006.

• George P. Sutton, Rocket Propulsion

Elements, JOHN WILEY & SONS,

INC., 2001.