Rockets and how they work By Jan-Erik Rønningen Norwegian Rocket Technology [...

Rockets and how they work

By Jan-Erik RønningenNorwegian Rocket Technology[ [email protected] ][ www.rocketconsult.no ]

Version: 1.30 2008

Contents

Rocket history Rocket Principle Fundamental Rocket Elements The Solid Propellant Rocket The Liquid Propellant Rocket The Hybrid Rocket Motor

Rocket History 1 The Chinese is claimed by many to be the

inventor of the black powder (about 200 B.C) and thus the rockets

Newer findings indicate that it is India that should be honored instead

However, old Chinese documents describe long tradition in making various black powder charges for use in firecrackers and rockets mostly for frighten bad spirits during religious happenings and during various festivals and celebrations.

The Chinese also developed rockets and flame torches to be used in combat against their main enemy, the Mongols.

Rocket History 2 The Arabs learned the art of rocketry

from the Mongols and the Europeans from the Arabs.

The Europeans developed the rocket technology further, i.e. between the 14th and 16th century: A English munch named Roger

Beacon improved the black powder prescription for use as rocket propellant, fire crackers and for use in canons.

A French man improved the hit accuracy of his artillery rockets by launching them from tubes.

An Italian (Fontana) experimented with rocket powered surface torpedoes which could ran into the cavalry or set ships on fire. One successfully did!!

Rocket History 3 The interest of the rocket as a weapon

went into a hibernation during the 17th century, mainly because of the poor accuracy compare to the more accurate and destructive canon. Further improvements were necessary.

A new dawn of rocketry appeared during the 18th century and especially some hundred years after Sir Isacc Newton had published his famous three laws.

During the 19th and 20th century many men were to become well know: Ziolkowsky, Hermann Oberth, Robert H. Goddard, Eugen Sänger, Werner von Braun, Korolev and many more

Rocket History 4 After the WWII the race for space

between USA and former Soviet escalated and accelerated the development of rocket technology to what we know and use today.

Sputnik I – World first artificial satellite launched 4. October 1957

Apollo 11 and Neil Armstrong – First man on the Moon20. July 1969

Vostok 1 and Yuri A, Gagarin – First man in space 12. April 1961

The Rocket Principle 1

Newtons 2. law:

Newtons 3. law: force = opposite force

amdt

vmdF

)(

Rocketdt

dp

Exhaustdt

dp

dt

vmd

dt

dp exhaust

Rocket

)(

The Rocket Principle 2 A chemical rocket is a reaction device

that brings with itself the oxygen needed for combustion and thus for generating thrust for positive propulsion

Rocket Elements – Main Parts

Convergent Divergentsection section

t ei

c

VeVtVc

c : chamberi : entrancet : throate : exitV: velocity

F

Rocket Elements - Thrust

impulseexhaustexhaustexhaust

exhaust

productsreaction

rocket

Fvmvdt

dm

dt

vmd

dt

dp

_)(

Ambient Pressure

Ambient Pressure

Ambient Pressure

Exit Pressure

)(_ aeeeforcepressure PPAPAF

)(_ aeeeforcepressureimpulse PPAvmFFF

F

Rocket Elements - Nozzle Flow

[4]

or

0

:expression above thetingDifferenta

const. lnlnln

:eq.1 of logaritm natural thenow take weproceeding Before

[3]

:as writtenbe can 2 eq. flow, ldimensiona-one and change potential no assume weSince

height :z and )( weight specific : speed, : vdensity, : pressure,:p

:where

line) streama along (const. [2] 0)(5.0

:friction) no (assuming equation Bernoullifamous the toleading

flow, particle fluidsteady a describe toutlilized be canlaw second Newtons

[1] .

:states mass of onconservati theconduit, a varying ghflow throu fluida When

2

2

A

dAd

v

dv

v

dv

A

dAd

vA

v

dv

v

dp

g

dzvddp

constvAm

0! dA/dv 1, MaWhen

[10] 1dv

dA

:gives eq.8 of grearrangin A

1 Ma :flow Supersonic

1 Ma :flow Subsonic

:conclude can we whichFrom

[9] )1(

dp

:us gives eq.8 and 4 Eq.

[8] )1(

1

v

dv

:form toeq.7 withmerged befurther can 3 Eq.

[7] 1

:as writtenbe 6 eq. now with can 5 Eq.

[6] and

:density withpressure of s variation torelated is sound of speed

theless), friction and (adiabatic flow isentropic assume We

[5] 1

:gives [4] [3]

2

2

2

2

22

2

2

Mav

A

Ma

Ma

A

dA

MaA

dA

A

dAMa

v

dp

a

vMa

pa

A

dA

ddpv

v

dp

s

Flow

Flow

Pe>Pa (under expansion)


M~0 M=1 M>3P=Pk Ph~0.5Pk PeSubsonic Transonic Supersonic

Pe=Pa (optimum expantion)

Pe<Pa (over expansion)

Entrance Throat Exit


0.15 0.2 0.25 0.3X-posisjon

-0.05

0

0.05

Y-p

osi

sjon

AM3.43.23.02.82.62.42.22.01.81.61.41.21.00.80.60.40.20.0

Laval dyse, ekspansjonsforhold=8.3

Machtall konturer [-]

Rocket Elements - Total Impulse

0,00

5000,00

10000,00

15000,00

20000,00

25000,00

30000,00

35000,00

0,000 1,000 2,000 3,000 4,000 5,000 6,000 7,000

Time (s)

Th

rus

t (N

)

b

tb

t tFdttFI 0

)(

Static Firing a Rocket Motor

NSR 30kN Hybrid Rocket Motor, 20s test

Rocket Elements - Specific ImpulseSpecific Impuls Values for Various Chemical Propellants

830

1442 14701825 1880

22002600 2630

3240

3796

10000

0

2000

4000

6000

8000

10000

12000

75% KNO3 +15% S +10% C

H2O2 +KMnO4

65% KNO3 +35%

C6H14O6

75% KClO4+ 17.5%Asphalt +7.5% Oil

82%NH4NO3 +

11% HTPB +7% Additives

60% NG +40% NC

78%NH4ClO4 +

15% HTPB +7% AL

RFNA + RP1 LO2 + HTPB LO2 + LH LH2 + U235

Sp

ec

ific

Imp

uls

[N

s/k

g]

Non Chemical

Rocket Propellant Condition Exampel of Use ISP [Ns/kg]Black Powder (75%KNO3 + 15%S + 10%C) Pressed Powder Fireworks 830Hydrogen Peroxide H2O2(l) + Potassium Permanganat KMnO4(s) Liquid/Solid Hobby Rockets 1442Candy Propellant (65%KNO3 + 35%C6H14O6) Hot Casted Hobby Rockets 147075% KClO4 + 17.5% Asphalt/Tar + 7.5% Oil Casted Hobby Rockets 182582% NH4NO3 + 11% HTPB + 7% Additives Casted Gassgenerator 1880Double Base (60% Nitroglycerine + 40% Nitrcellulose) Extruded Missiles 220078% NH4ClO4 + 15% HTPB + 7% Al Casted Ariane 5 SRB 2600RFNA + Kerosene (RP1) (1.43 Mixtureratio) Liquid X-1 Rocket Plane 2630LOX + HTPB Liquid/Solid Launch Vehicle 3240LOX + LH (3.40 Mixtureratio) Liquid Ariane 5 1.stage 3796LH + Solid Core Nuclear Reactor (Fisson of U235) Liquid/Solid Nerva Test Motor 10000

d

bsp m

tFI

The Solid Propellant RocketConstruction:

Motor Case Thermal Insulation

Propellant NozzleIgniter

Solid Propellant Rocket

PARAMETER CHARACTERISTIC VALUE RANGE

Specific Impulse [m/s] 2000-2600

Burn rate [mm/s] 1-15

Chamber Pressure [MPa] 7-20

Combustion Efficiency [-] 0.95-0.98

Thrust to Weight Ratio High

Throttle? Difficult

Stop and Restart? Not Practical

Lifetime? Long (7 to 15 years)

The Solid Propellant RocketPropellant Mixing:

300 gallon approx. 1200kg of propellant

The Solid Propellant RocketPropellant Grain Geometry:

Advanced Grain Burn Evolution

The Solid Propellant RocketAriane 5 Solid Rocket Booster:

DATA for one SRBPropellant: HTPBPropellant Mass: 237T(158 cars)Motor Mass: 273T(182 cars)Thrust: 5400kN (about 550T!!!!)Burn Time: 130s (2.16min)Mass Consumption: 1.82T/sTVC: +/-6deg vectorable nozzle

The Liquid Propellant RocketConstructions:

The Liquid Propellant Rocket



Burn Rate [mm/s] N.A



Thrust to Weight Ratio Low

Throttle? Easy

Stop and Restart? Easy

Lifetime? Very Long (> 10 years)

The Liquid Propellant Rocket

The Hybrid Rocket

NozzleCombustion ChamberPressurized Nitrogen or Helium

Start/stop Valve and pressureregulator

Valve Electronics

Check Valve Solid Grain“Mixing” ZoneInjector

Liquid

Flow Valve and Regulatorwith control electronics

The Hybrid Rocket



Regression rate [mm/s] 0.2-5



Thrust to Weight Ratio Medium

Throttle? Easy

Stop and Restart? Easy

Lifetime? Very Long (>10 years)

The Hybrid Rocket

Combustion Principle – The Candle Light

Air Air

Paraffin Wax

Liquid

Gas (H, C)

The Hybrid Rocket

How is it to work as an “rocket scientist”?

Rockets and how they work By Jan-Erik Rønningen Norwegian Rocket Technology [...

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