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DEPARTMENT OF AERONAUTICAL AND ASTRONAUTICAL ENGINEERING

W. C. Nelson, ChairmanHarm Buning, Acting Chairman,~ Ioq

With the commemoration of its Golden Anniversary in October, 1964, the

Department is entering its second half century of instructional and research

activities in the field of aeronautical and astronautical engineering. During

recent years the curriculum has continued to be modified to keep in step with

the fast changing developments in the aeronautical and aerospace industries.

Fundamental theoretical and experimental studies are carried out in the

,several departmental facilities both on the Central and North Campuses. A

summary of these activities follows.

Aerodynamics Laboratory. The characteristic blunt shape of currently used

reentry bodies has created considerable interest in the nature of the flow

around such bodies. Research is carried out to determine the dynamic

stability of blunt bodies in supersonic as well as in subsonic flows. Some

understanding of these problems is obtained by observing the characteristic

motions and wakes behind disks falling through a liquid (see photographs).

Other studies on this type of body involve measurements of the effect of tur-

bulence on the laminar heat transfer in the stagnation point relion.

In' a study of the behavior of electric arcs in air streams 8uch an arc

with currents up to 1000 amp. was successfully stabilized in a supersonic

flow by means of a crossed magnetic field. The properties of the arc, such

aa current, voltage drop, arc slant, and magnetic field strength, were

measured.

Other experimental studies involve the statistical 8tructure of the unsteady

flow near the wall in a turbulent boundary layer. This work is part of a long-

range 8tudy of boundary layer turbulence, probing into the causes of aircraft

cabin noise and problem8 associated with underwater sonar detection method8.

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Theoretical invet5ti~ations dl~al with the aHvlTlptutk iu\'iscid hypt"rsunic

flow at large distanct's Crf)m a bll1nt budy; th(.. viscuus hypt.rt4onic Wakt' im-

mediately downstr~an1 of a sh'nd~' r C(.IO~; r(.laxat ion pht'non\rna of dilute

plasmas; and the struC"tlll'e of weak curved shockwavl's.

Information and Control Engint'ering. 1'ht~ rt'st'arch activitit.s of the stafC

include the areas of contrul theory. systemR random process theory. data

communication. telemetry. and the general desiqn and applicath>n oC analog

and hybrid cornputt-rs (lo~ic control~ed analog computers) to broad arf!as

including automatic and manual control. strl1ctu\-al dynamic~. non1in~~r- ,

systems. and simulation of airc raft and sP,"CEf ve'bi~~.r.IJ. Rest.arch in co~ts:ol,.. . :~~ ... -. -

is principally in th('. cu~:r nt1 y ac-tivlo a rea: of optimal r'ont rul theory and- compu-

tational methods. The area of application is very broad and includt's at'rospaceo

systems.

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Propulsion l.abnratory. "h~ staff c::ontinues its {undamt'ntal Rtudies of detona-

tive combustion process.'s. This general art'a of study is prompted by com-

bustion. i'1stai)ility p:roblem~' in liqui~ propellant rp~~ttt :q1otors.. w~~hcan,.. ~': ,9__.,." _ .~,, "f' _ "_ - _, . - _ .0:'" to , '~. . -,.

result in de,s~rU(:*ion of tile anotorrand the resulting failure of a mission.

Specifically. one t.heoretical and experimental program involves tbe investiga-

tiol\. of steep press.urf! waves passing 9ve1\ liquid fuel drops i~ a surro~nding. , J) . "! ..

la8~ous oxidizer. Here it is important- to asse""s the influence of the resulting- , . ...'. ',,'

. combustion' on ,the ~hockwave as this inay be the main cOf1tributing factor to

combustion instability. Another phas80f this work concerns itself with. the

details of an interaction between the.- detonation wave and the surrounding

compressible medium.

Modern and future propulsive devices involve the simultaneous flow of

liquid or solid particles with the gas phase. Theoretical and experimental

studies are underway to investigate the differences in velocity and temperature

between particles and gas and the resulting affect on the performance. The

problem is also pertinent to the radiation {rom rocket exhausts and the wakes

-=-=--- -or-hype-r-some reentry bodte-s-.- -.- ,-. --

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In high velocity wind tunnels and in certain types of space rocket motors

and power generators there is the problem of gases condensing to liquids

or solids. Information with regard to the rate of condensation is required.

Studies of these phenomena are being conducted in an arc-discharge hyper-

sonic wind tunnel along with theoretical studie s utilizing advanced digital

computers.

The structure of rocket exhausts at very high altitude is an important

problem from the standpoint of heating the rocket base. communication with

and detection of the rocket. This problem area is being studied spectro-

graphically in the laboratory using a DC arc-generated jet. Theoretical

studies are in progress which seek to account for the particle-like nature

of the gas flow at the very low pressures realized.

Extensive space endeavors and the requirement for higher temperature

aerodynamic facilities has led to the need for an understanding of the energy

exchange processes between an electric arc and gases. Toward this end a

fundamental study of the heat conduction from an alternating current arc to

the surrounding gas flow is being conducted. Also, efforts are being expended

to increase the operating level of a 3-phase AC arc heater to higher tempera-

tures and pressures as a potential source for an hypersonic wind tunnel.

High Altitude Engineering Laboratory. The staff of this laboratory is con-

tinuing its work in aeronomy and high altitude radiation investigations. The

research activities led to the firings of sounding rockets at such far-flung

locations as Fort Churchill. Kwajalein. and from aboard .he USNS Croatan

at southern latitude s. Firings were also carried out at Wallops Island,

Pacific Missile Range and Keweenaw Point. Michigan.

The experimental program of research on atmospheric radiation processes

included aircraft and balloon flight tests of the NIMBUS high and medium

resolution infrared radiometers, which were accepted as payloads on the

NIMBUS and TIROS satellites to be launched later this year. Laboratory

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work involved the development ofa technique to calibrate radiometers in the-I

spectral range 0.4 to 4 microns. A high resolution (5 cm ) infrared inter-

ferometer is being developed for Fourier spectroscopy investigations of

planetary atmospheres. The theoretical program includes studies of radia-

tive heating and cooling in the stratosphere and mesosphere and the deter-

mination of atmospheric temperature structure from satellite radiation

measurements.

The major effort of the aeronomy program is the measurement. in

sounding rocket experiments, oJ the neutral composition to 200 km with a

massenfilter-type mass spectrometer. The quadrupole mass spectrometer,

adapted for longtime satellite usage, has been accepted for installation on

the Polar Orbiting Geophysical Observatory, the first one of which is to be

launched in the summer of 1965.

The refraction technique program is involved in the evaluation of the

operational capability of an instrument for a meteorological satellite. which

measures the refraction of starlight as viewed through the atmosphere from

which density, temperature and pressure can be inferred.

In the area of structural mechanic sand aeroelasticity the primary research

interests are panel flutter and nonlinear vibrations. Both problems have be-

come important because of the large degree of flexibility of modern aerospace

structures prompted by the necessity of minimum weight design. Panel

flutter can occur in the outer surfaces of such vehicles when they encounter

large dynamic pressures in the supersonic flight range. Nonlinear vibration

analysis is dictated by large amplitude motion which may occur.

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