Appendix AChamber Valve Characteristic

The position of a valve can be read by the MCC system from end switches; theyindicate the full open or close status (Fig. A.1). In a valve switch test characteristictime delays can be identified.

Fig. A.1 Time delay inmilliseconds for themanoeuvring of a valve(chamber valve hydrogen of aVulcain engine) (Photo: DLR)

Open

Close

250 256 371 248

Ope

ning

Com

man

d

Fee

d B

ack

Clo

sed

Dis

appe

ars

Clo

sing

Com

man

d

Fee

d B

ack

Ope

n A

ppea

rs

Fee

d B

ack

Ope

n D

isap

pear

s

Fee

d B

ack

Clo

sed

App

ears

W. Kitsche, Operation of a Cryogenic Rocket Engine, Springer Aerospace Technology,DOI 10.1007/978-3-642-10565-4, C© Springer-Verlag Berlin Heidelberg 2011

95

Appendix BChamber Igniter Characteristic

The chamber igniter is itself ignited by a pill of powder at its tip. A wire in a short-circuit conducting a current of 6 A for 50 ms ignites the pill. Thus the main powdercharge is ignited and the internal pressure (Fig. B.1) of the pyrotechnical elementincreases. At a pressure of about 120 bar, three membranes which had sealed theelement burst. Via three openings at an angle of 120◦ to each other the hot smokeis injected into the combustion chamber and ignites the fuel/oxidiser mixture. Thetime taken to reach 80% of the maximum pressure inside the igniter in this contextis called the ignition delay (Fig. B.1).

Figure B.2 is a series of photos showing the ignition of the fuel/oxidiser mixtureand the flame evolution in the combustion chamber. The photos were taken with ahigh speed camera (2000 frames per second) via a mirror below the engine.

0

20

40

60

80

100

120

140

0 100 200 300 400 500 600 700

Time [ms]

Pre

ssu

re [

bar

]

Fig. B.1 Ignition delay of a chamber igniter (Photo: DLR)

Fig. B.2 Ignition of a Vulcain-combustion chamber (Photo: DLR)

97

Appendix CMeasurement and Correction of the Ovalityof a Vulcain Nozzle

The measurement and correction of the ovality of the Vulcain nozzle has been per-formed regularly since 1993. The protocol (Fig. C.1) documents such a procedure.The diameter was measured at different circumferential positions (before and after)and with a special clamping device the nozzle exit was reformed into a shape closeto the circle.

Fig. C.1 Inspection sheet(Inspection sheet: VOLVO)

99

Appendix DCompare of Flow Schemes Vulcain/Vulcain 2

Fig. D.1 Compare of Flow Schemes Vulcain/Vulcain 2 (Photo: SNECMA)

101

Appendix EFlow Scheme of the Ariane 5 Main Stage

Fig. E.1 Flow scheme of the Ariane 5 main stage (Photo: SNECMA/EADS (formerly SEP/Aerospatiale))

103

Appendix FFlow Scheme of Vulcain 2

FC

EC

BO

R VC

BP

TM

CB

PT

M1

CB

PT

M2

LE

FP

1

LE

FP

2

BE

VC

EV

VG

H

EV

VC

H(V

CH

+VM

RH

)

EV

VG

O

EV

VC

O

EV

VP

(VP

O +

VP

H)

EV

BO

(BC

O +

BG

O)

EV

VG

C

FE

C

CE

VC

HG

VA

CO

GV

AC

BE

VB

CB

CO

2

CBGO2

CBGO1

SF

AV

GO

CB

CE

R

V U

L C

A I

NF

PO

E

F B S O

FB

SH

FP

HE

F C E R

V G H

V G OV

PH

VP

O

VG

C

VM

RH

LM

RH

L G O

LT

H

LT

O

CB

JPH

SF

AV

GH

F P O M

FP

HM

CB

H

CB

JTH

L G H

DM

CB

GH

AG

GG

LE

H

LE

OL F H

LC

H2

F P H R 1

AC

CP

CB

JTO

F P R O

CB

JTO

S

F E P 1

LE

P

Réchauffeur hélium

LP

RO

Mis

e à

jour

:

Sch

éma

fo

nct

ion

nel

flu

ides

pré

sen

té e

n p

has

e p

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ée

Hyd

rog

ène

liqu

ide

Hyd

rog

ène

gaz

eux

Oxy

gèn

e liq

uid

e

GO

X+G

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itio

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itio

nn

emen

t

Gaz

ch

aud

Gaz

ch

aud

+ G

He

Hu

ile G

AM

Hél

ium

gaz

eux

Ce document est la propriété de SNECMA . Il ne peut être reproduit ou communiqué sans son autorisation préalable et écrite

du d

ocum

ent o

ffici

el

Diff

usio

n p

rovi

soire

pour

info

rmat

ion,

en

atte

nte

d'un

e éd

ition

CB

CH

LC

H1

VC

H

TP

LH

2

SF

AV

CH

TP

LO

X

CB

CO

1S

FA

VC

O

LC

O

VC

O

L F P O

Mat

érie

ls

EC

CH

(co

nditi

onne

men

t GH

e)

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CH

(pu

rge

LH2)

CT

PC

H (

chas

se e

rgol

s)

FE

FP

(év

acua

tion

huile

GA

M)

PP

H (

Pre

ssur

isat

ion

RLH

2)

BM

H (

bala

yage

hyd

rogè

ne)

PG

D (

GH

e co

mm

ande

)

EV

SC

P (

purg

e S

CP

)

TP

CO

(pu

rge

LOX

)

LAO

(al

im.L

OX

)

LAH

(al

im.L

H2)

LAH

(co

nditi

onne

men

t GH

e)

ET

AG

E

EV

AE

(al

imen

tatio

n LH

e)

PP

O (

pres

su. R

LOX

)

LAO

+ E

VS

CP

(co

nditi

onne

men

t GH

e)

BM

O (

bala

yage

TP

O)

MO

TE

UR

EP

C A

5E

SY

NO

PT

IQU

E V

UL

CA

IN 2

0111

99

Fig

.F.1

Flow

sche

me

ofVu

lcai

n2

(Pho

to:S

NE

CM

A/E

AD

S(f

orm

erly

SEP/

Aer

ospa

tiale

))

105

Appendix GFlow Scheme of Vinci

Fig

.G.1

Flow

sche

me

ofVi

nci(

Phot

o:SN

EC

MA

)

107

Appendix HMixtures of Oxygen and Nitrogen Closeto Their Boiling Points

The main component of an oxygen (O2) supply to a rocket engine is the run tankwith liquid O2. If the tank is pressurised with nitrogen (N2) the condensation of N2at the surface of the liquid O2 has to be considered. The equilibrium of both fluidsclose to their boiling point is shown in the phase diagram (Fig. H.1).

For the calculation of the dewpoint and boilingpoint curve (H.1) and (H.2), [16]were used; the vapour pressure Pi (T ) was calculated according to [21].

Boiling curve X ′1 = P − P2(T )

P1(T ) − P2(T )(H.1)

Dew curve X ′′1 = −P1(T )P2(T )

P1(T ) − P2(T )

1

P+ P1(T )

P1(T ) − P2(T )(H.2)

The symbols are:

T temperature of the mixture (here the temperature of the liquid O2),P pressure of the mixture (here the pressure in the vessel),P1(T ) vapour pressure of the first component (here N2),P2(T ) vapour pressure of the second component (here O2),X ′

1 liquid mole fraction of N2,X ′′

1 gaseous mole fraction of N2.

Temperature of the Mixture[ K]

Mixture of Liquids

Mixture of GasGas/Liquid Mixture

Pressure = 2 bar

75

80

85

90

95

100

0 0,2 0,4 0,6 0,8 185

90

95

100

105

110

115

120

Nitrogen Fraction of the Mixture

Mixture of Liquids

Mixture of Liquids

Mixture of Gas Mixture of Gas

Temperature of the Mixture [ K] Temperature of the Mixture [ K] Pressure = 1 bar Pressure = 6 bar

Gas/Liquid Mixture

Gas/Liquid Mixture

90 K Line 90 K Linie

90 K Line 75

80

85

90

95

100

0 0,2 0,4 0,6 0,8 1

Nitrogen Fraction of the Mixture

0 0,2 0,4 0,6 0,8 1

Nitrogen Fraction of the Mixture

Fig. H.1 Phase diagram of O2/N2 mixtures at 1, 2 and 6 bar (Photo: DLR)

109

110 Appendix H Mixtures of Oxygen and Nitrogen Close to Their Boiling Points

In fact the mixture is not homogeneous in time and space and is not at equi-librium. The pressure is defined by the pressurisation system; above the liquid itis constant, below the surface it increases with depth. The temperature around thesurface is dominated by the temperature of the liquid oxygen, normally close to90 K. If the tank pressure is held at 1 bar for a long time only very small fractions ofN2 can be found in the liquid. When the pressurisation is started the condensationat the surface begins and the N2 fraction increases.

We can assume that the condensed N2 remains mainly in the upper layers of theliquid (see below). After test, particularly when the pressure is reduced to 1 bar, theN2 as the more volatile component evaporates again. The typical evaporation rateof a vacuum insulated tank is 0.1% of the inner volume per day. For the oxygentank (200 m3) on the facility P5 that means 200 L per day. Hence it takes 7 days tore-evaporate the N2. But in the normal test cycle the tank is refilled the day after thetest. Due to this dilution the concentration of N2 decreases to a tenth part, which isa far more drastic decrease than that due to the evaporation. Nevertheless, for theengine test the N2 fraction in the oxygen means pollution. A sample taken during anormal test period had a fraction of 0.36% of N2 in O2.

Diffusion of Liquid N2 in Liquid O2

In order to check whether a fast diffusion can distribute the N2 fraction all overthe tank, we have to look for the solution of the diffusion equation (H.3) at theapplicable conditions. We also need the coefficient of N2 diffusion in liquid O2.

The diffusion equation has the same mathematical structure as the heat conductionequation (H.5) for which we find the general solution (H.6) in [16] and transfer itto the diffusion equation. For the diffusion coefficient D no measured value couldbe found in the literature or on the internet; therefore the Stokes-Einstein-equation(H.4) was applied.

Diffusion equation∂ c

∂ t= D

∂2c

∂ xi∂ x j(H.3)

where c is the concentration, t the time, and xi the position vector (or, more cor-rectly, the coefficients of the components of the position vector).

The Stokes-Einstein equation gives us

D = K B T

6 π μ R0= 97.6 × 10−9 Ns/m2 (H.4)

where K B = 1.38 × 10−23 as the Boltzmann number, T = 90 K as temperature,μ = 6.5 × 10−6 Ns/m2 as the dynamic viscosity (of O2 at 90 K, 6 bar) and R0 =10.4 × 10−11 m as particle radius (of N2).

We obtain the general solution for the concentration c(x, t) in the one dimen-sional case:

Appendix H Mixtures of Oxygen and Nitrogen Close to Their Boiling Points 111

c(x, t) = c0 + c1x +∑

n

{exp

(−D a2

nt)

(An cos(an x) + Bn sin(an x))}

(H.5)

with the constants c0, c1, an, An, Bn .The importance of N2 diffusion in the O2 tank is checked in an example. Assume

at time t = 0 a pure layer of liquid N2 is situated above a pure layer of liquid O2.Both layers have the same thickness, together d = 100 mm. (this complies with theN2 mass which normally condensates in our tank):

c(x, t) = cmax

2− 2 cmax

∑

n>0odd

{exp

(−D

(nπ

d

)2t

)1

nπsin

(nπ

dx)}

(H.6)

The statements at (H.5) and (H.6) are transferred from the solution of a heatconduction problem, here the adiabatic bar [16].

We can see (Fig. H.2) that the relative concentration c/cmax after 2 h of diffusionis still far from the homogeneous (50% of cmax at each point) state. Hence we canconclude that the process of diffusion cannot really distribute the N2 in the tankwithin the relevant small period of time. Pressurisation, depressurisation and fillingprovide a much stronger mixing process of the two components.

–5

–4

–3

–2

–1

0

1

2

3

4

5

0 0,2 0,4 0,6 0,8 1

For t = 2 hours

For t = 0

For t = infinite

Hei

ght a

bove

the

poin

t of c

onta

ct [c

m]

Relative concentration of oxygen after two hours

Fig. H.2 Diffusion in a layer of N2 and O2 (Photo: DLR)

Appendix IJet Pump

A fluid flow engine which increases the total pressure of a fluid is called a pump (fora liquid) or a compressor (for a gas) (Fig. I.1). A very simple engine of this categoryis the jet pump. It has a nozzle to create a jet (gas or liquid) of high velocity but lowpressure. Due to the low pressure the jet is able to suck in fluids from a somewhathigher pressure level. This fluid is carried along and energy is transferred from thejet to the fluid. Behind a mixing passage the flow is guided in such a manner thatthe kinetic energy is transformed into pressure energy, this pressure being higherthan the original pressure of the fluid. Hence we rightly state that the fluid carriedalong is compressed or pumped. The jet pump has no moving or rotating parts, itcan provide high power despite small dimensions and it is very suitable to suck offfluids from low pressure regions. For short term operation (e.g. 1 h) on a test facilitythe jet pump is preferred in comparison to other pumps (e.g. rotary vane pump) dueto lower investment and maintenance costs.

Cavity

Jet NozzlePressure Supply Exit

Mixing Passage Suction Flange

Fig. I.1 Gas jet pump on the facility P5 (Photo: DLR)

The convergent/divergent jet nozzle is driven at high pressure (e.g. 40 bar) andprovides a supersonic jet of low static pressure. The jet increases in diameter andimpinges the inner wall of the mixing passage. Up to that point it sucks in gas fromthe cavity and creates here a pressure decrease. At the impingement point (respec-tively circle) a sonic shock or a series of shock patterns occurs. Via the suction flangefurther gas is sucked in. Behind the mixing passage the jet is further compressed andleaves the jet pump as a subsonic jet.

For the design of a jet pump and for the computation of the operational parame-ters the equations of balance for energy and mass are applied, as well as functionsof gas dynamics and empirical coefficients.

113

114 Appendix I Jet Pump

One operational mode of a jet pump is the zero-suction-mode. This mode meansan operation at closed suction valves; the cavity is evacuated and no suction flowis possible. We study a full supplied jet pump (reference point) in this mode. Asnormal the jet impinges the inner wall, the Mach number MA in this point dependingon the diameter of the jet at that point. The sonic shock causes a strong loss of totalpressure. The ratio of total pressure behind the shock to the ambient pressure isequivalent to the pressure ratio (static/total) at the exit. For computation purpose wemake a variation of MA, compute the pressure loss across the shock and computethe pressure ratio at the exit (Fig. I.2). In the solution MA has to match the correctstatic pressure at the exit which adapts to the ambient pressure. The area and thestatic pressure of the jet at the impingement point can be computed as well fromMA and hence follows the suction pressure in zero-suction-mode.

For the supply of the jet pump with 14 kg/s N2 at 288 K the computation of thezero-suction-mode is summarized in Table I.1. Even without knowledge of the losscoefficients in the supersonic jet and in the mixing passage, we have good agreementof the computation with the measurement during operation.

Fig. I.2 Computation sections of the jet pump (Photo: DLR)

In the normal operation the suction flow has to be considered. The lower thesuction pressure of the pump the higher the performance. Flow and pressure can beshown as a characteristic of the jet pump. On the other hand the flow also depends onthe leak ratio of the connected device (e.g. a vacuum chamber) and on the pressureloss in the line between. The behaviour of this device is also given as a character-istic. The intersection of both characteristics is the reference point of the jet pump(Fig. I.3).

To calculate the properties of the mixture of jet and suction flow (Table I.2) weapply the balance of mass and energy and assume that the entropy of the mixture is

Table I.1 Gas dynamic parameters in zero-suction-mode

Static pressure Total pressure Area Mach numberSection [bar] [bar] [m2]

E 0 Supply 40 40E 1 Nozzle throat 21.13 40 0.0015 1E 2 Nozzle exit 0.1924 40 0.0201 4.24E 3 Directly before the shock 0.02 40 0.0935 6.232E 4 Directly before the shock 0.9052 1.012 0.0935 0.4023E 5 Directly behind the shock 1 1.012 0.283 0.13E 6 Suction flange 0.02

Appendix I Jet Pump 115

Characteristic of a Jet Pump

05

10152025303540

0 1 2 3 4 5 6 7 8

Suction Flow [kg / m3]

Su

ctio

n P

ress

ure

[m

bar

]

Fig. I.3 Characteristic of a jet pump (Photo: DLR)

Table I.2 Gas dynamic parameters at 3 kg/s suction flow

Static Total Masspressure pressure Area Mach flow

Section [bar] [bar] [m2] number [kg/s]

E 0 Supply 40 40 14E 1 Nozzle throat 21.13 40 0.0015 1 14E 2 Nozzle exit 0.1924 40 0.0201 4.24 14E 3 Directly before the shock 0.0287 20.9 0.1083 5.28 17E 4 Directly before the shock 0.93 1.04 0.1083 0.403 17E 5 Directly behind the shock 1 1.04 0.283 0.2375 17E 6 Suction flange 1.04 3E 7 Surface of the jet 1.04

equal to the sum of entropy of both flows. Indeed, we know the impulse of the massflow but not the forces on the inner surface and therefore we do not use the balanceof impulse.

(mcp TG

)Jet + (

mcp TG)

Suction Flow = (mcp TG

)Mixture (I.1)

mJet + mSuction Flow = mMixture (I.2)

(m s)Jet + (m s)Suction Flow = (m s)Mixture (I.3)

s = cP ln (Ttotal/Treference) − RN2 ln (Ptotal/Preference) (I.4)

The specific heat cP of both components (N2 and air) is considered as equal, mis the mass flow and Ttotal and Ptotal are total temperature and pressure of the gas.Total in contrast to static is used her in the sense of gas dynamics (see Remark I.1).The specific entropy s refers to Treference = 288 K and Preference = 1 bar. RN2 is thespecific gas constant of nitrogen.

116 Appendix I Jet Pump

Remark I.1 The technicians on the test facility also use the term static for a pneu-matic system when no consumer load is active (no consumption). The system is,e.g. adjusted to 20 bar before the consumer is activated, the pressure may dropthen, e.g. by 2 bar when the consumers are active. This use of the term must notbe confused with the context of gas dynamics. In general all pressure values in theAriane program (another context of terms) are given as absolute values relative tothe vacuum pressure of 0 bar.

Because jet and suction flow have both Ttotal =288 K and Ptotal suction flow =1 barwe can conclude by (I.3) and (I.4):

(m ln

(Ptotal

Preference

))

jet=

(m ln

(Ptotal

Preference

))

mixture(I.5)

From (I.5) we can compute the total pressure before the shock and with thetotal temperature and mass flow we continue our computation analogue to the zero-suction-case.

The calculated suction pressure was 28.7 mbar, and 115 mbar was measured. Thedifference is only 86 mbar (8.6% relative to 1 bar ambient pressure) but, on the otherhand, the result of this nominal case is just in the order of the measured values.However, the system was designed for a pressure of 200 mbar in the casing, and themeasurement was taken at 300 mbar.

For isentropic compression of 3 kg/s from 29 mbar to 1 bar a power of 1512 kWis required. The supply of the jet pump (40 bar, 14 kg/s) is 7536 kW which means anefficiency of η = 1512/7536 = 0, 2. This efficiency is much less than for any otherhydraulic/mechanic pump, the reason for the low efficiency being the high entropyproduction across the sonic shock.

The characteristics of the jet pump were measured in pre-tests in which the endof the suction line was closed except for a combination of orifices. The casing wasnot connected to the jet pump.

The mass flow during operation depends on the leakage of the casing. As soon asthe casing pressure is below 0.52 bar a critical pressure ratio is reached at the pointsof leakage and the leak flow does not increase further more (except if the leak areaincreases). The desired pressure in the casing can be adjusted by the regulationvalves which quasi-create a desired pressure loss in the line. Hence we have

Pcasing = Psuction + �Pline + �Pvalve (I.6)

The pressure loss at a sonic/subsonic transfer is not avoidable. The highest losscan be assumed across a normal shock (perpendicular to the flow), planar obliqueshocks (wedge like) having less pressure loss and the oblique shock at the tip ofa cone again having less pressure loss. The loss across shocks at the inner wall ofa tube (as we have it in a jet pump) is a bit less than at a normal shock but stillsignificantly higher than in a wedge like flow. In particular in a jet pump of highpower (e.g. for the vacuum chamber of an upper stage engine) it is desirable to

Appendix I Jet Pump 117

reduce the pressure losses across the sonic shocks. For that purpose an rotationallysymmetric centre body is integrated behind the mixing passage. The sharp cone hasthe perfect gas dynamic performance; it causes a slight deviation of the flow anddecelerates the flow to a low Mach number. But the tip would have to bear a veryhigh thermal load and therefore the centre body normally has a blunt nose whichcreates a detached shock in front of it.

Appendix JFluids of the Test Process

For the operation of a test facility it is of essential importance to consider carefullythe properties of the fluids used within the operation (test). We use the term fluidsbecause some substances are used in liquid as well as in gaseous form. Further onthe possibility of freezing of the fluids must also be checked. The most importantfluids on a test facility for a cryogenic rocket engine are listed in Table J.1.

At ambient condition (15 ◦C, 1 bar) the hydrogen and helium is much lighter thanair the gas climbs up and may accumulate at the ceiling of a closed room.

Remark J.1 In the design of the test cell of the facility P5 the roof is lower on theside of the tower of the building and higher the on the outward side. Due to thisdesign the ascending hydrogen is deflected from the building. On the other hand,unfortunately, rain water on the roof is directed towards the building. Any holes inthe test cell roof directly cause problems because the penetrating water is collectedin the thrust cone like in a giant funnel and than directed to the engine where it cancause failures on electrical and electronic components.

Even in the liquid state (20 K, 1 bar) hydrogen is relative light, its specific densityequals the density of rock wool. The specific density of liquid oxygen is of the orderof water.

Remark J.2 On the facility P5 in November 1991 severe damage occurred due to abroken water line. The chute for the hydrogen tank filled up temporarily almost tothe top. The tank was at that moment not far from floating. The empty steel tank of200 tons and its hydrogen filling of approximately 30 tons were much less than itsdisplacement of more than 600 tons of water. Thanks to the fact that the tank wasnot totally covered by water and that the connections to the facility did not break,no greater damage to the test facility occurred.

Remark J.3 The routing of the oxygen feed line is vertical for several metres and isequipped with flow turbines. To fill the line from the top is harmful for the turbines,and therefore an alternative filling procedure was developed. In order to avoid awater hammer in the oxygen feed the closing times for the valves in this line haveto be defined with extra care.

119

120 Appendix J Fluids of the Test Process

Table J.1 Fluids in the test process of a cryogenic test facility

Hydrogen Helium Oxygen Nitrogen

Specific density at15 ◦C and 1 bar

kg/m3 0.0841 0.167 1.337 1.17

Ratio of the specificheat Cp/Cv = κ

1.41 1.66 1.4 1.4

Specific density at theboiling point

kg/m3 70 125 1140 810

Molecular weight M kg/kmol 2.016 4.003 32 28.01Specific gas constant

RS

J/(kg K) 4124.16 2077.02 259.82 296.83

Triple point bar 0.072 – 0.0015 0.125kg/m3 80 or 0.13 – 1306 or 0.01 867 or 0.68K 13.95 – 54.4 63.15

Critical point bar 13.16 2.3 50.9 33.98kg/m3 31.57 70 405.8 281K 33.2 5.2 154.8 126.3

Evaporation heat r at1 bar

kJ/kg 460 20.59 238.7 198.2

Melting point at 1 barTm

K 14 1 54.8 63.3

Boiling point at 1 barTb

K 20.4 4.2 90.2 77.3

Specific heat atconstant pressure cp

kJ/(kg K) 14.32 5.23 0.917 1.038

Air Propane Water hydraulic oil

Specific density at15 ◦C and 1 bar

kg/m3 1.21 1.88 1000 869

Ratio of the specificheat Cp/Cv = κ

1.4 1.14 1.33

Specific density at theboiling point

kg/m3 581 1000

Molecular weight M kg/kmol 44.1 18Specific gas constant

RS

J/(kg K) 287.00 188.53 461.91

Triple point bar 0.0061kg/m3 1000 or 0.005K 273

Critical point bar 42.42 221kg/m3

K 370 647Evaporation heat r at

1 barkJ/kg 426.5 2258

Melting point at 1 bar K 86.5 273.15 (213)Boiling point at 1 bar K 231 373.15Specific heat at

constant pressurekJ/(kg K) 1.005 1.595 1860

Appendix J Fluids of the Test Process 121

When heat is introduced into a cryogenic fluid, and this is mostly the case becausethere is no perfect insulation, evaporation and a pressure increase occurs. Thereforeany segment for a cryogenic fluid has to be equipped with safety components (burstdisc, safety valve) and the process has to be conducted in such a manner that thefluid is never locked.

In cases of direct contact of different fluids the reactivity (e.g. detonating gas)has to be considered. In cases of extreme temperature differences condensation andicing has to be expected. These effects can also occur on the outer surface of tubesand engine components.

Remark J.4 During the first start up of a sub-system involving liquid helium, atsome tubes a lot of air was liquefied. Besides water, liquid N2 in fact also raineddown from the tubes.

Remark J.5 In a combustion chamber for research purpose running on liquidhydrogen/oxygen, an annular icing around the injection elements was detected. Fueland oxidiser are ducted through the injection plate and thus keep it at a very lowtemperature despite the combustion downstream. In the recirculation zone directlybelow the injection plate (face plate) there is of course water as the product of thecombustion. This water, cooled down, deposits as ice at the face plate.

If a gas gets in contact with a cryogenic fluid, condensation and mixing canoccur (see Appendix H). Due to the contact a pressurisation gas normally coolsdown, increases in density and decreases in pressure. Sometimes the term collapsefactor is used to describe this effect but this is no mysterious phenomenon and it isnot necessary to measure the factor empirically; it can be explained and calculatedwithin thermodynamics.

Another term used for an effect in the context of cryogenic fluids is cryo-pumping. Remark 5.4 describes impressively what happens when a gas comes intocontact with a surface whose temperature is lower than the saturation temperature ofthe fluid. The gas increases in density, condenses to liquid and the pressure decreasesif this occurs in a closed cavity, or further gas is sucked in if the cavity is open.

The most meaningful diagram concerning the thermodynamic state of a fluidis the enthalpy-entropy-diagram (h-s-diagram, Fig. J.1). In particular, a status orprocess close to the two-phase area (liquid/gaseous) can be visualised properly inthe h-s diagram. At normal condition (1 bar, 0 ◦C) hydrogen, oxygen and nitrogenare far from their two-phase area. But the processes in a cryogenic rocket engine arerunning close to that area or traverse the two-phase area.

Extremely high temperatures (e.g. the H2 fraction in the exhaust of the rocket)are not included in Fig. J.1. The properties of hydrogen in this state are given inTable J.2.

At extremely high pressures (e.g. in a bottle at 250 bar, 0 ◦C) the gas has no idealbehaviour any more. In the given example the compressibility factor z = pv/(RST )

is 1.13.

122 Appendix J Fluids of the Test Process

0

100

200

300

400

500

0 2 4 6 8 10

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 10 20 30 40 50 60

20,4 K

0°C

1 bar

300 bar

High Pressure BottleAmbient Condition

Saturation Line

Enthalpy [kJ/kg]

Entropy [kJ/(kg K)]Area of Turbo Pump Process

Combustion Chamber Inlet

115 bar

140 K

Entropy [kJ/(kg K)]

Enthalpy [kJ/kg]

158 bar 115 bar33 K

PumpingProcess

Fig. J.1 Enthalpy-entropy diagram of hydrogen (Photo: DLR)

Table J.2 Hydrogen at normal conditions and at high temperature [5]

Pressure bar 1 100Temperature K 273.15 3000Density kg/m3 0.0887 08117 × 10−3

spec. Enthalpy kJ/kg 3573 48460spec. Entropy kJ/(kg k) 52 81.67Cp kJ/(kg K) 14 18.49Cv kJ/(kg K) 10 14.35Speed of sound m / s 1261 4026κ = Cp/Cv 1.41 1.29

Appendix KPressure Transducer

In the typical pressure transducer on the test facility and on the rocket engine,strain gauges are widely used to transform pressure (as the physical parameter)into voltage (as an electrical parameter). The strain gauge is a flexible membranewith thin wires glued to the surface. The strain gauges are arranged in the mannerof a Wheatstone bridge. The membrane is deformed according to the pressure andthe deformation changes the resistance of the strain gauges (Figs. K.2–K.4) andhence a measurement voltage is available on the Wheatstone bridge. As an exam-ple, in Fig. K.1 the strain gauges (resistors) R1, R4 are expanded and R2, R3 arecompressed if the membrane is deformed.

Measured Voltage

Sensed Voltage

Supply Voltage

R1 R3

R2 R4

Fig. K.1 Strain gauge in a Wheatstone bridge measurement element (complementary resistancesfor temperature compensation are not shown) (Photo: DLR)

The measured voltage is proportional to the supply voltage. On test facilities thesupply is normally far from the sensor and a loss in the cable must be considered.Therefore the effective supply voltage is also measured on the sensor by means ofa so-called sense line. That means there are six wires (plus screen) in one sensorcable (Table K.1). A higher resistance of the sensor would reduce or avoid a voltageloss but it has the disadvantage that dynamic pressures cannot be measured becausethe capacity of the cable combined with a high resistance of the sensor causes aconsiderable damping in the measurement chain.

123

124 Appendix K Pressure Transducer

Fig. K.2 Strain gauge in a pressure transducer (Photo: DLR)

Fig. K.3 Disassembled pressure transducer (Photo: DLR)

Fig. K.4 Sensor with cut casing (Photo: DLR)

Table K.1 Typical parameters of a pressure transducer

Supply voltage 12 VCable voltage loss 2 VSensed voltage 10 VResistance of the cable 60 OhmResistance of the sensor 300 OhmMeasured voltage at full signal 20 mV

Appendix LMeasurement Chain

The design of a measurement chain depends on the parameter to be measured (tem-perature, pressure, vibration etc.) and on the measurement mode (range, acquisitionrate, precision etc.).

Normally the chain from the sensor into the computer has several plugged andfixed cable connections and has at least one unit for amplification and signal adjust-ment. Normally the analogue signal is converted at the entrance of the computer.Inside the computer the signal is treated again for different purposes (archiving,regulation, display, monitoring).

Sensor Plug

Cable tree

Plugged connection

Rigid connection

Arrangement array

Amplifier rack

Filter

A/D converter

Computer

Fig. L.1 Typical measurement chain between a pressure transducer and the computer system(Photo: DLR)

125

Appendix MValve Control Circuit

Most the valves on the facility as well as on the rocket engine are opened/closed bymeans of a pneumatic actuator. The activation of the actuator is again controlled bya pilot valve, an electrically driven open/close valve which switches the in/outlet ofthe actuator to a pressure gas source or to a venting line (atmosphere). The electricalactuation of the pilot valve is realised by a chain of electrical components betweenthe valve and the control computer.

Fluid Valve

Pneumatic Actuator Venting Line

Pressure LinePilot Valve

Electical Power

Junction Box

RelayRack

Battery

Signal Sources

MCC System

Back Up System

Manual System SystemSelection

Fig. M.1 Typical valve control circuit for an open/close valve (Photo: DLR)

The outer tube of the vacuum sections (Fig. M.3) is a rigid, welded or well sealedtube of stainless steal. The outside of the conventional insulation (Fig. M.4) looksalmost the same, but here we have a thin aluminium cover which protects the hardfoam insulation.

127

128 Appendix M Valve Control Circuit

Buffertank

Pneumaticlines

Pilot valves

Fig. M.2 Rack of pilot valves (Photo: DLR)

Fig. M.3 Automatic valves for cryogenic lines (integrated in a vacuum box) (Photo: DLR)

Appendix M Valve Control Circuit 129

Fig. M.4 Automatic valves for venting lines (integrated in “conventional” insulation)(Photo: DLR)

Appendix NOxygen Detector

Design

The measuring cell consists of a plastic casing which houses two electrodes emergedinto an electrolyte. The cathode is a gold plated grid, the anode is a cylinder made ofsintered lead. The tightness of the component is good but gas tightness is guaranteedby a thin Teflon diaphragm.

Fig. N.1 Gas analyser rack with oxygen detectors (blue casing) (Photo: DLR)

131

132 Appendix N Oxygen Detector

Measurement Principle

When the anode comes into contact with oxygen a reduction – oxidation reaction isinitiated. Due to the reaction a potential difference (voltage) is created between theelectrodes. The voltage is proportional to the partial pressure of the oxygen. Becausethe cell is influenced by temperature an adjustment by means of a thermistor isnecessary. The voltage at the contacts is amplified and displayed.

References

1. S.A Durteste, Transient model of the VINCI cryogenic upper stage rocket engine, AIAA JointPropulsion Conference, Cincinnati, 2007

2. J. Gastal, J.R.L. Barton, VULCAIN: A cryogenic engine for ARIANE 5, lecture series 1993-01 von Karman Institute for Fluid Dynamics

3. A. Haberzettl et al., VULCAIN 2 flight load simulation device, EUCASS European Conferencefor Aerospace Sciences, Moscow, 2005

4. D.T. Harrje, F.H. Reardon, Liquid propellant rocket combustion instability, NASA SP-194National Aerospace and Space Administration, U.S.A, 1972

5. R.C. Hendricks et al., NASA TN D-7808 Cleveland, OH, 19756. C. Hujeux, W. Kitsche, Evolution of the rocket engine testing process, AAAF Association

Aeronautique et Astronautique de France, Versailles, 20027. INERIS Retour d’expérience issu de la mise en ouvre d’un réservoir d’hydrogène liquide haut

pression, Journée technique, 07.10.20038. Exploitation of various internet websites9. P. James,Technological readiness of the vinci expander engine, IAC International Astronauti-

cal Congress, Glasgow, 200810. W.H. Kitsche, Simulation of flight conditions on a test facility for rocket engines, EUCASS

European Conference for Aerospace Sciences, Brussels, 200711. W.H. Kitsche, Pollution control on a test facility for a cryogenic rocket engine, EUCASS Euro-

pean Conference for Aerospace Sciences, Versailles, 200912. K. Koch, Analysis of signals from an unique ground-truth infrasound source observed at IMS

station IS26 in southern germany, Pure Applied Geophysics, 167, 401–412, Basel, 201013. C.R. Koppel et al., A platform satellite modelling with ecosimpro: simulation results, AIAA

Joint Propulsion Conference, Denver, 2009, AIAA 2009, 541814. P. Magnant, B. Juery, and N. Chazal, PF52 test facility for cryogenic engines and subsystems,

SpaceOps Conference, Huntsville Alabama 2010, AIAA 2010-225315. R.E. Martin, Atlas II and IIA analyses and environments validation, Acta Astronautica

35(12), 199516. I. Müller, Grundzüge der Thermodynamik mit historischen Anmerkungen, 3. Auflage

(Springer, Berlin, 2001)17. G. Ordonneau, F. Lévy, Low frequency oscillation phenomena during VULCAIN shutdown

transient, AIAA Joint Propulsion Conference, Salt Lake City, 200118. Holy Spirit, Bible (Christian Church, Worldwide)19. G.P. Sutton, Rocket Propulsion Elements (Wiley, New York, NY, 1986)20. M. Williamson, Dictionary of Space Technology (Adam Hilger, New York, NY, 1990)21. W. Wagner, Multifluid Package (Ruhruniversität Bochum, 2003)

133

Index

AAcceleration, 63Acceptance, 11–12, 81, 87Acoustic chamber, 68Acoustic load, 67–72Acoustic panel, 68Actuator, 11, 53, 55, 64, 127Adjustment instruction, 88Air, 120Altitude

conditions, 7, 61, 69facilities, 69facility, 7, 37, 39, 60–62simulation, 60–61

Amplification, 54, 125Amplifiers, 16Analogue gauge, 47Analogue signal, 50, 125Anemometer, 18Anomaly, 25, 75, 77–78Ariane 5, 9–12, 103Ariane 5 ECA, 72, 78Ariane program, 6, 11Arianespace, 9–10ARTA (Ariane Research and Technology

Accompaniment), 12Attitude control system (SCA), 12Automation, 48

BBalance of impulse, 115Battle ship tank, 64Bearing, 21, 27–28Bench access, 85Bipropellant, 28Boiling point, 4, 109–111, 120Boltzmann number, 110Booster(s), 63, 65–67

shut down, 65–66

Boroscopic inspections, 16Boundary layer effects, 60Bubble counter, 18Buffeting, 69Buffeting effect, 69Bunker, 7, 39, 47, 49, 54, 84–85Burner system, 73Burn time, 7Burst disc, 19, 70, 84, 121

CCabling plan, 16, 88Campaign, 10–16, 70Carbon dioxide, 42Cavitation, 27, 65Centre body, 117Challenger, 17Chamber ignition, 11, 30Chamber valve, 27–30, 95Characteristic of the load, 35Chemical propulsion system, 1, 27Chemical reaction, 60Chill down, 4, 27–28, 42–43

criteria, 28, 42phase, 4, 24, 27

Chromatograph, 23Chronology, 88–89Chugging, 33–34Cleaning procedure, 19–20, 23–24Cleanliness

check, 16, 19criteria, 23–24level, 20requirements, 24

Closed loop, 30–31Collapse factor, 121Combustion, 30, 33, 36, 60, 121

chamber, 19, 35, 46, 60, 97pressure, 29, 34–35

135

136 Index

Commissioning, 79, 81–82Component level test, 7Compressibility factor, 121Concentration, 24, 55, 110–111Condensation, 21, 45, 109–110, 121Condenser, 60Conditioning procedure, 23Configuration management, 80–82Control

building, 40, 49, 75bunker, 39, 49, 54desk, 7element, 31, 53parameter, 16, 30room, 7, 47–50, 55, 78, 92technique, 48

Convergent/divergent nozzle, 19Cooling system, 58–59, 70, 73Cooling water, 56, 58Corrosion, 20Crack detection, 16Critical point, 120Critical pressure, 33, 116

ratio, 116Cryo circuit, 27Cryogenic engine, 4, 24, 57Cryogenic fluid, 4, 27–28, 74, 84Cryo pumping, 121

DData acquisition, 16, 53–54Data base, 14, 16, 25Data exploitation, 89Demineralised water, 23Design phase, 27Design point, 9, 35–36Detonator, 70Development, 9–12, 46–47Development test, 9, 10–11, 31Diffuser, 60Diffusion, 105, 110–111Dismounting, 89Diverse redundancy, 85Documentation, 13–14, 77–78, 87–90Double failure, 85Double-walled tank, 42Dry run, 15, 26–27, 77, 89, 92Durability, 11Dynamic forces, 71Dynamic seal, 16–17Dynamic viscosity, 110

EEfficiency, 1, 77, 115Ejector, 7, 56–57, 61–62, 70–71

jet, 56–57, 60Electromagnetic valve, 53Emergency shut down, 85, 88Engine

characteristic, 30control, 30, 53cycle, 4, 25exhaust, 60regulation, 11test, 2–3, 7, 9, 23, 25–38, 110

Engine level test, 7Entropy, 114–115, 121–122Entropy-enthalpy-diagram, 121Entropy production, 115Erection, 24, 39–40, 79, 83, 87ESA (European Space Agency), 9–10, 46, 92Evaporation heat, 120Evaporation rate, 110Evaporator, 74Exhaust

cooling, 59, 73guide tube, 73guiding, 56, 57–59jet, 3, 12, 57, 58–60

Expander cycle, 4–5, 33, 37–38Explosion proof, 83

FFacility operation, 83Facility operator, 83, 88–89Facility system, 15, 75, 89–90Failure

case, 74, 83test, 11

Feed back, 50, 53, 89, 95Feed line, 44–46, 63–64, 66–67Feed system, 4, 43–46Fibreglass, 71Film cooling, 11Filter, 20–21, 23, 125Fire

brigade, 84–85detection, 85fighting, 74, 85–86

Flare stack, 74Flight

acceptance, 9conditions, 6, 63–72line, 45, 66

Index 137

Flow scheme, 101, 103, 105, 107Fluid circuit, 20, 23–24Fluids, 4, 42, 84, 109, 119–121Flushing, 27, 33FMECA, 80, 83Fog, 75Foreign gas, 20–21, 23Fuel

oxidiser combination, 19storage, 39tank, 3, 39transfer, 15

Functional aspects, 21Functional test, 16–17

GGas

analyser, 24, 55, 131detector, 17, 55dynamics, 60, 113, 115generator, 4–5, 22, 28–31, 33

cycle, 4–5Gaseous oxygen, 21Gauges, 16, 47, 123Gimbal, 12, 89

HHazard area, 75, 83–84Heat

conduction, 43, 110jacket, 38transfer, 74transition, 61

Helium, 16–17, 23–24, 119–121Hermes, 10Homogeneous redundancy, 85Hot run, 4, 13–16, 18–19, 24, 26–34, 40–41,

43, 47, 52, 56, 59, 65, 67–68,71–72, 84, 88–89

Hot run sequence, 52Humidity, 20–21, 23–24, 42, 74Hydraulic actuator, 12, 64Hydraulic dummy, 45Hydraulic oil, 26, 120Hydrogen, 4, 43, 46, 56, 119–122

IIgniter, 29, 53, 90, 97Ignition

delay, 97system, 37, 57, 74

Industrial return, 9Inert gas, 17, 27, 55Injection element, 21–22, 35, 121

Injector plate, 21–22Inlet pressure, 29, 38, 63–65, 67Inspection, 13–24, 42, 58, 85Inspection request, 88Instruction manual, 89–90Insulation, 42–43, 127, 129Integration, 13, 15, 89Interface, 13, 26, 46, 53, 63Internal leak, 18, 24, 55Interventions, 88–89Isentropic compression, 115

JJet pump, 60, 113–117

LLaunch table, 57Launcher, 1–4, 9–10, 12, 63–64, 66, 69–70Launch pad, 3–4, 11, 75Launch procedure, 28Lead item, 81Leak

detector, 17flow, 18, 71, 116measurement, 16–18rate, 71ratio, 71–72, 114

Leakage, 16–18, 55, 116Life time, 42, 59, 78Lift off, 63Lighting arrester, 75Lightning, 75, 77Light pen, 48Limitations and constraints, 77Limits of operation, 35Liquefied, 60, 121Liquid oxygen, 4, 21, 22, 64, 66, 110, 119Load simulation device (LSD), 69–72Logbook, 13–14, 25

MMach number, 60, 114, 117Maiden flight, 6Main engine, 41Main frame computer, 49, 50Main stage, 103Majority logic, 32Malfunction, 9, 11, 17, 31, 85Management process, 15Manual, 13, 47, 51, 88–90Mass flow, 7, 30, 33–35MCC (measurement, control and command

system), 12, 15, 28–32, 46–55

138 Index

Measurementchain, 16, 45, 53, 123, 125device, 75request, 15–16, 88

Melting point, 120Men rated, 10Microscopic examination, 23Mixture ratio, 29–30, 34–35, 37, 47Modifications, 79, 81Molecular weight, 120Monitored parameter, 31–32Monitoring, 3, 31–32, 40, 54–55

NNCR (non-conformance reports), 15, 78–79Net positive suction head (NPSH), 43Nitrogen, 23–24, 109–111, 120–121Non conformance, 15, 78–79Normal shock, 116Nozzle extension, 19, 69, 72Numeration system, 87

OObjective, 3, 10–11, 77, 79, 89Oblique shock, 116Open loop, 30Operational

aspects, 3–8, 19, 37, 39, 87behaviour, 34, 65cycle, 3–4, 6, 10–11, 28limit, 35–36mode, 77, 114point, 3, 9, 11–12, 30–31, 33, 35–37

Operator, 12, 46, 88–89, 92Oscillation, 31, 33–34, 45, 65–67Output specification, 88Ovality, 99Overpressure, 23Oxidiser, 7, 27, 41–46, 121Oxygen, 21–24, 28–30, 32–34, 64–66,

109–111, 119–121, 131–132Oxygen pump, 11, 16, 28, 32, 36

PParticles, 20–21, 23–24Passenger Test Request, 89Passive insulation, 42Performance, 15, 34–37

map, 11, 29, 31, 34–37Periphery, 46, 50, 53Periscope, 47Phase diagram, 109Physical data, 16Pilot burner, 11, 56

Pilot valve, 22, 53, 127–128Piping diagram, 88Pneumatic actuator, 24, 53, 64, 127Pneumatic system, 115Pogo oscillation, 66–67Pollution, 4, 19–24, 110Post test check, 89Powder charge, 97Power consumption, 40Pressure

gauge, 47, 74loss, 63, 114, 116–117pressurisation system, 3, 21, 43, 63, 110profile, 26, 28, 63–65ratio, 114, 116transducer, 123–124

Procedure, 2–3, 12–15, 23, 25–28, 77–82Progress meeting, 81–82Propagation of the sound, 76Propane, 73, 120Propane tank, 73Propellant, 1, 3–4, 28, 30, 76Propulsion cycle, 4, 28Propulsion system, 1, 3–4, 34, 37, 46Punctual check, 32Purge lines, 39Purity, 19, 23Pyrotechnical element, 20, 25, 29, 53, 97

QQuality, 77–78Quality assurance, 9, 14, 25, 81

RRAMS, 83Ratio of the specific heat, 120Raw value, 54Real time, 31Reception, 71Red button, 52Redline, 31–32, 77

margins, 77Reference point, 35, 114Regulation, 11–12, 15, 30–31, 35, 37, 47, 50,

53–55algorithm, 31, 55cycle, 31valves, 47, 53, 70, 116

Reignitability, 37Reliability, 6, 10–11, 19, 21–22, 40Relief valve, 64Re-liquidation, 73Remote control, 48–49, 84Reproducibility, 77

Index 139

Rest position, 83–84Review board, 78Reviews, 15, 77, 81Risk

analyse, 15, 79–80management, 79–80, 83

Rock wool, 119Roll torque, 12Rotary vane pump, 44, 61, 113Rules, 14, 31, 91–93Run tank, 7, 41–43, 45–46

SSafe state, 52Safety

component, 121engineer, 75inspection, 85officer, 85principle, 84radii, 83status, 83system, 7, 83, 85valve, 84, 121

Satellite, 3, 9Saturation temperature, 121Sealing, 16, 21Sense line, 54, 123Sensor

failure, 31signal, 41, 50, 54

Sequence, 14, 29–33, 49, 50–52Service pressure, 83Shaft speed, 32, 35–36, 54Shock pattern, 113Shock wave, 69Shut down, 3–4, 37–38, 52–53, 65–67

sequence, 11, 29, 31–33Shuttle, 6, 10, 17, 57Signal conditioning system, 53–54Single-point failure, 85Sonic shock, 69, 113–115, 117Sound level, 68Sound measurement, 68–69, 76Space shuttle, 6, 17, 57Space shuttle main engine, 6, 57Specification of the campaign, 88Specific

density, 119–120gas constant, 115, 120heat, 115, 120impulse, 4, 21

Specimen, 7, 12–16, 25

SPF, 83Standards, 92Start up transient, 29–30Steady state, 34Steam generator, 7, 39, 60Stoichiometric point, 29Stokes-Einstein-equation, 110Storable propellant, 76Storage device, 46Strain gauges, 123–124Subsonic, 33, 69, 113, 116Suction flow, 114–116Suction line, 71, 116Suction system, 57, 60, 70–71Supersonic, 33, 69, 113–114Surge effect, 45Switch board, 48–49

TTank, 39, 41–43, 45–46, 63–64, 109–111

runs, 63Test

abort, 31–32, 47, 77analysis, 15area, 75campaign, 11–16, 70cell, 39, 56–58, 60–61, 119conduction, 75, 91configuration, 25–27, 80, 88–89execution, 9, 12, 14, 89facility, 3–8, 39–43, 46–48green light, 78–80leader, 13–16, 52objective, 3, 79, 88–89period, 9–24, 78phase, 85plan, 77, 93position, 56process, 79–80, 85, 119–122readiness, 15, 27, 77–78, 80

meeting, 15, 77–78, 80report, 15, 88–89request, 14–15, 25–28, 87–89requirer, 14–15, 25, 77–78, 81

Thermal behaviour, 70Thermal load, 25, 42, 57, 117Throttle, 11, 30, 63–64Thrust

frame, 56vector, 53, 59

control, 53, 59Tightness, 17, 24, 70, 74, 91, 131TNT equivalent, 83

140 Index

Torque meter, 12Total pressure, 113–115Total temperature, 115Traceability, 77Training matrix, 91Transport, 1, 10, 13, 40, 89Triple point, 120Turbine, 16–17, 29–30, 37–38Turbo pump, 29–30, 32, 35, 63, 65

starter, 29Turbulence, 60Two-phase area, 121

UUltrasonic bath, 23Uninterrupted power supply, 40Upgrades, 78Upper stage engine, 37, 60, 116

VVacuum

chamber, 7, 37, 60, 114, 116insulated, 7, 42, 66, 110section, 42–43, 127test cell, 69

Validation process, 14, 54

Valve control, 127–129Vapour pressure, 66, 73, 109Venting line, 127, 129Venting point, 27, 33Video monitor, 55Vinci, 5, 37, 61, 107Viscosity, 110Visual inspection, 16, 18–19Voltage loss, 123–124Vulcain, 4–5, 7–11, 13–14, 21–24, 101, 105

WWatch dog, 40, 80Water

hammer, 33, 65, 119tower, 39, 58

Weather conditions, 73–76Wheatstone bridge, 123Wind, 76–77Work instruction, 12–15, 90Work plan, 88

ZZero-suction-case, 115Zero-suction-mode, 114

About the Author

Wolfgang Kitsche works as a senior test leader at the test centre for rocket enginesof the German Aerospace Center (DLR), Institute of Space Propulsion, Lampolds-hausen, Germany. Impressed by the manned space flights of NASA in the 1960she decided as a young boy to become an aircraft engineer. He studied aerospaceengineering at the Technical University of Berlin and focussed on propulsion andthermodynamics. Several internships in the field of physics of propulsion at VFW-Fokker, Bremen and some years work on turbo machinery at Borsig, Berlin extendedhis theoretical knowledge before he entered his current position, which he oncecalled in an interview a present from heaven (see Job 1.21).

141

142 About the Author