REPORT ON MEETING (SANITIZED) ON FEBRUARY 4, 1958, - INFORMAL DISCUSSION OF LTA AERODYNAMIC CONSIDERATIONS

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03642A001300040017-5
• Release Decision: RIPPUB
• Original Classification: C
• Document Page Count: 20
• Document Creation Date: December 22, 2016
• Document Release Date: June 14, 2012
• Sequence Number: 17
• Publication Date: March 7, 1958
• Content Type: MEMO

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CONFIDENTAL
To:
From:
Subject:
SUMMARY
March 7, 1958
Report on Meeting with on February 4, 1958 - Informal
Discussion of LTA Aerodynamic Considerations
The concepts proposed in Proposal 11510-B for powered plastic balloons
were discussed with thS people in an informal table discussion.
Because of the rather radical departure from the existing blimp technology and
use of the possible startling gains in performance which would be possible,
elt it would be well to have an interchanae_of thoughts and opinions between
The meeting would give a chince to ask questions regard-
ng present and planned airship programs and airship requirements. The meeting
would also allow to discuss accomplishments in the free and captive plastic
balloon field and to discuss pertinent parts of the design problem, including
materials, fabrication techniques, performance capabilities, power plants, con-
trol techniques, configuration, etc.
BuAer's interest appeared principally in two areas:
(1) To increase airship speed to 90-95 knots
(2) 20,000 ft altitude capability for an AEW ship.
It was pointed out how the boundary layer concept of aerodynamics allows an
Insight into the mechaOsm of air flow about airships and considerable gain
in both speed and duration will be possible through the use of flow separation
prevention techniques. To achieve these_aains, an aerodynamic research program
such as the one proposed is necessary. experience would indicate the
feasibility of the plastic material in increasing the altitude capability and
for carrying the loads, but the weathering qualities of the material are not
known now and need to be investigated.
Butter acknowledged that the as presented for the first year appeared
technically feasible; the funding for the program is to be done by ONR and
should be expanded to include materials research.
I. Participant?
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II. Introduction
-2- March 71 1958
The introduction was made by on the purpose of the meeting,
and he was most generous in telling about the co capabilities as well as
the historical and current association of the u.op1e (present at the meet-
ing) with the stratosphere balloon programs.
He then presented who first outlined and then went into
greater detail on why we have submitted proposals for powered lighter-than-
aircraft, what our experience has been in the this area, what we hope to aqcomplish
by our suggested program; and, finally, he solicited guidance from the
airship people on what they felt would be the future trend in LTA. programs and
whether what we have proposed and would present (at the meeting)actually made
sense.
He acknowledged that we were experienced mainly in free balloons which, however,
were capable of carrying tremendous loads to extreme altitudes. We have ex-
tended the principles learned here to captive balloons, which are also capable
of carrying considerable loads to lower altitudes (in the order of 5,000 ft),
however, capable of withstanding winds of fairly high velocity (in the order
of 50 knots). e have in a logical extension of free balloon work, made a
low cost study in which the feasibility and application of powered
plastic balloons were considered. The approach taken was a fundamental one,
at the recommendation of the sponsor and with the concurrence of the project
people. As a result of this study, and of additional later work, it appears
that the *wring of a plastic balloon is feasible and that, by a rather modest
program, a significant break-through could be made in the LTA concept.
For example, by the use of boundary layer control (here defined as the preven-
tion of flow separation and the extension of the laminar region), it will be
possible to reduce the fineness ratio from the 4.17:1 to a much lower ratio,
perhaps 1.5:1. In so doing, the volume to weight ratio is improved and the
configuration is such that it will be less cross wind dependent.
The problem of flow separation will be solved by suction, ring stabilization
and stern propulsion. Combining the ring stabilizer with the propeller would,
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in effect, be a ducted propeller with increased efficiency. Since the static
thrust of a ducted propeller is almost double that of an unshrouded propel-
ler, low speed controllability would be greatly improved. Then, combined
with the use of the more efficient materials now available, the size ship
required for a given task is greatly reduced and performance is appreciably
improved.
These, then, were the concepts upon which our proposals were based.
Since we had the background experience as noted earlier, and since we had the
company support, capable people in the necessary fields of interest (materials
research, manufacturing, quality control, government inspection and specifica-
tions, structures, aerodynamics and field operations), we felt it would not
be out of order to suggest changes in the state of the art, changes nite
advantages and based on sound fundamental principles. However, since
has rience in LTA and would be a possible future user, we wanted to
ask Do these ideas make sense? Or, conversely, what i looking
for in an airship?
was the spokesman for the------]expup and indicated that the
position of the LTA field was as follows: For some years the question of high
altitude capability has been the subject of discussions. As long as the
main objectives have been in the ASW area, a requirement for low altitude capa-
bility only has existed. However, now, when AEW work is being considered, the
altitude limitations of present LTA is a real problem. Other people in the
Navy might have requirements for extreme altitudes; however, he did not now
have such a requirement - but he could immediately use a LTA having a 20,000
ft altitude capability.
Such a LTA should have certain capabilities, especially insofar as wind capa-
bilities are concerned. For example, present blimps have a 60 knot limitation
on speed - and many times winds of 50 knots are encountered over the ocean.
A new airship should have a 90 knot capability, since speed and maneuverability
are especially critical in ASW warfare. At the present time, the ZPG-2 airship
Is a good ASW vehicle and there is no need for the development of a new one.
substantiated the remarks made by and added some remarks
about the present altitude capabilities (which are rather low).
made some comments on a long range wind tunnel program to study
the blimp aerodynamics, as well as a continuing program on the study of new
fabrics and design techniques. The ASW airship should include many of the
Improvements resulting from these programs. The mounting of the engine on the
fins, stern or in the wake has been studied - the stern mounting scheme, in
addition to aerodynamic advantages, offers the distinct advantage of physical
separation from the instrumentation (important in sonar problems).
discussed the "Aerocap" captive balloon capabilities and sizes.
e presen sizes being designed are up to 40 ft length (134,000 ft3), with
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a lifting capability of 5,000 lb to 2,000 ft above the surface. The above
balloon is being developed on an AEC program and will be delivered in May.
The load capability will be extended to 20,000 lb, with first deliveries to
be made by the end of the year.
The concepts in these captive balloons will be to utilize the plastic materials
to their best advantage. Because of this efficient use of material, the size
of balloon required will be smaller (and therefore more economical); and, be-
cause of the above, the weight of the balloon system will be reduced conserva-
tively by a factor of 2 or 3 over standard construction methods.
Pneumatic (inflated) fins will be used for heading control, since these balloons
are unpovered; however, it is felt that the principles shown can be extended to
powered airships.
discussed in some detail the various aspects of power require-
ments for the powered balloons, including some comments on the discrepancy
between the theoretical and the actual requirements (the latter being much
greater than predicted). In considering possible means for reducing the power
requirements, the work. of Prandtl, and the later compilation of Schlicting,
on boundary layer control is valid (and among the better reference sources).
These references conclude that blunt bodies (vs. pointed, streamlined bodies)
are not necessarily disadvantageous as long as the flow along the body is con-
trolled. The greatest drag occurs vhen the flow separates from the after body
(iiparting unrecoverable turbulent energy to the wake); thus, if this is
prevented, the drag will result mainly from the surface friction. Then, since
a blunt body has less surface area than a streamlined body, there is an addi-
tional reduction in drag. Also, a properly designed stern propeller can recover
a portion of the longitudinal wake energy caused by skin friction. Keeping the
flaw entirely laminar would be highly desirable but probably not attainable;
however, any gain in area of laminar flow would be an advantage over the
existing situation, and the proposed "fatter" body has a much larger favorable
pressure gradient than a streamlined body in its forward regions.
Present airships use about a 4.17:l fineness ratio, which has apparently proven
satisfactory; but, for the design proposed, the fineness ratio would be some-
where between the present fineness ratio and a sphere. The design would depend
on the results of the investigation, but it would include the results of the
study of the aerodynamics, structures, propulsion and control.
The aerodynamic problems would be attacked in full scale (tethered) balloons
through the measurement of boundary layer profiles. It is felt that the
extrapolation of data from small scale wind tunnel models will not give the
quantitative data necessary (mainly because tunnel turbulence masks the
phenomena being investigated). The similarity concepts of Reynolds number
have to be very carefully considered. For example, in consideration of the
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CONFIDENTIAL
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equation RN raiLp?VIP, the L term, if considered as a diameter, is no longer
appropriate. The momentum thickness, &, or the displacement thickness, cr ?
should be used (Prof. Hazen suggests that it be based on the length of run).
Maintenance of laminar flow along the forward body will be improved because
of the favorable pressure gradient. Turbulent separation will be prevented
by stern propellers, ring tails, and/or boundary layer suction and will be the
major gain.
The structure considered will consider plastic materials of types shown most
suitable. The support of the engine in a stern mounting is shown possible from
the consideration of the equation for a pneumatic beam, F = APRi. A consider-
able advantage is gained through the use of a low fineness ratio, since the
influence of the radius of the base of the beam (R) varies as the cube and,
inversely, as the length of the beam (L).
A stern drive is being considered using a ducted propeller. The propeller
assembly would be moveable or the flaw deflected to provide the control, thus
the fins would be eliminated. Such a scheme would provide a means of abetting
the flow maintenance and would provide a positive control without having fins
extending beyond the diameter of the blimp. The reduced exposed area would then
make the gust loadings less, and low speed controllability would be greatly
improved.
Mayer asked whether an inflated ring (propeller duct) had been considered.
The answer given was that it had been considered but that it is believed to
be less clean aerodynamically in an area where the aerodynamics are very im-
portant.
A question on whether we considered the limiting RN for laminar flaw as criti-
cal was answered to the affirmative. Some work at the David Taylor Model Basin
on 18 inch diameter sphere in both water tank and wind tunnel has shown a
correlation with the work of Fagg. This work shows the stability occurring
up to RN of 6 million; the airship we propose would have a RN of 16 million
(based on ship length).
Hollenberg questioned the length of laminar flow. He said that laminar flows
have been maintained to RN of 6-8 million but that the airship industry (with
all their experience) has been unable to extend the laminar flow beyond this.
Any irregularity in the surface trips the flow, including dust particles, but
it is especially sensitive to waviness.
Froehlich agreed that this was true, but bodies with the very strong favorable
pressure gradients have not heretofore been investigated at large body Reynolds
numbers. Theory indicates that the area of laminar flow is larger for bodies
with very strong favorable pressure gradients (ref. Schlicting, p. 344).
'GNP:0'411A'
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March 7, 1958
noted that various types of boundary layer control could
be used, including suction, venting, ejection of flow, etc.
ipointed out that the program (which studied the feasibility) had
been mainly concerned with the progress made in the last 10 years in free
balloons and how the knowledge gained might be utilized for a vehicle having
greater maneuvering (powered) capability. The study had looked at the funda-
mental problems which would have to be solved to arrive at an optimum vehicle.
Since a study of the boundary layer profile would be a necessary part of the
investigation, it appears that the captive type balloon would give meaningful
data if it were high enough to get above the earth's boundary layer or ground
effect. Possibly, a better technique would be one of selecting a calm day and
towing the balloon through an essentially calm atmosphere. has made
full scale flight boundary layer profile measurements on gliders. He has shown
that atmospheric motion is essentially of a larinAv nature, as compared to wind
tunnels where the motion is turbulent to varying degrees. Since the nature
of the air has a large influence on the growth of the boundary layer, it is
essential that tests be conducted in as near a laminar flow as possible.
talked about the work done by the Bureau of Aeronautics in making
wake surveys (using a pitot rake) of the BACA work on profile measurements,
and of the current work of on the full scale measurements of flaw
characteristics (using an operational blimp). He acknowledged that very little
was known about the boundary layer (and boundary layer control) on bodies of
this size and that much remained to_be done.
then discussed the very high altitude powered balloons, in which
a limited amount of lateral control might be used to maintain position, tra-
verse a latitude line, or maintain a flight vector different from the free
wind. If one considers what might be done today, utilizing only available
(and proven equipment), a modest capability appears possible. Considering,
for example, electric propulsion with silver cell batteries as the source of
power, a Class "C" shaped balloon (of the volumes. noted) would give the per-
formance shown in Figure 1. The battery weights were taken as 15% of the gross
weight and the efficiencies of the component parts were taken as follows:
electric motor, 75%; gearing, 95%; propeller, 75%.
An interesting attribute shown in this curve is the independence of the
performance (shown) on the altitude. A drag coefficient of 0.05 was assumed.
This value represents a conservative figure for conventional design with flow
separation control.
Figure 2 dhows a very interesting plot of the gross weight vs. the volume for
various altitudes. By plotting the weight of a 2 mil balloon (as shown), the
net weight carried can be immediately seen.
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For the very modest speeds being considered., power requirements at the higher
altitudes might be as low as 3-1/2 H.P. Because of the choice of electric
power, intermittent operation is possible (and probably desirable).
Operationally, such a balloon might be associated with a ship. It could be
packed into a small volume and then launched at the appropriate time. Wind
effects could be negated by steaming downwind; and/or, a launching platform
could be used in the same way free balloons are now launched.
In reply to a question fron
the program envisioned by
was outlined into the two basic areas, as follows:
I. Aerodynamics of Airship
A. Theoretical:
Carry out the necessary theoretical work associated with
laminar and turbulent boundary layers and solve the dynamic
stability equations associated with the airship shapes under
consideration.
B. Experimental:
Field verification, with full size models, of the theoretical
work.
C. Document results in a report which will be applicable to
future airship designs.
II. Altitude Expansion
Demonstrate the feasibility of propelled stratospheric vehicles with
an electrically-propelled balloon of modest capability.
then pointed out the need for continuing improvements - the Navy
needs the 1959 models now. He also pointed out some of the operational problems
which they face - with the wind and the low altitude capabilities of the present
blimps being the worst problems.
He then consented further that our present proposals appeared to break down
into two main areas of endeavor: (1) a small blimp with stern propulsion and
improved aerodynamic characteristics and (2) a very high altitude balloon hav-
ing propulsion as an auxiliary feature for some mobility.
In answer to a nuestinn nf definition of low altitude, he defined 7,000 ft as
low altitude. then said that he wanted an airship that would be
useful up to 20,000 ft. Therefore, as a definition of terms, 0-20,000 was
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defined as the low altitude (which would be immediately useful tcr-----1 /
and above this would be the high altitude (which at this time would be mainly
of academic interest). The -20 ltitude would satisfy both ASW and AEW
requirements at this time, pointed out that, conservatively, a
2 to 4 time improvement in duration and reduction in drag is possible with
the program suggested; and the performance required certainly appears feasible.
asked what we proposed for materials which could give a blimp
vs c cou ? be taken out of the hangar at 7?F into a 35 knot wind which slams
it into the hangar without damaging the balloon.
said that the law altitude balloons (0-20,000 ft) could utilize present
Mylar stronger than the polyethylene films) but of thicker gauge. Also, a
new "weatherable" Mylar, having a weathering life of at least a year, has been
recently tested. in Florida. An even more recent development is the Type "R"
film which villbsme an expected life of 10 years. The schemes can also be
used for increasing the weathering life. For example, metalizing surface
treatment might yield an increase in weathering life by a factor of 4 or 5.
Pigmenting would be another means for increasing the life. Other combinations
of materials (i.e., Fortisan and Dacron) might be used to supplement properties.
Whitnah showed samples of a "scrim" material, used in some of our work, which
was made of Fortisan and polyethylene. The strength figures associated with
this material agreed with the Goodyear work, according to Mr. Marcellino.
We have not used the Dow materials, since the early Saran materials were
rather difficult to work with, requiring an oil surface coating to prevent
"blocking", having a tendency for tears to propagate, and being very critical
in being heat-sealed. We have not had contact with Dr. Grebe of the Styrofoam
Division of Daw Chemical, who is reportedly interested in blimps.
mentioned that we have had an active balloon materials research
program in progress for over two years. Since balloons pass through the
troposphere, it was necessary to consider in great detal the effects of low
temperature and that much of this research has concerned itself with this
aspect.
said that up to six years ago was pretty much in the dark
on materials. However, with the program started then, they have learned
much about the properties of materials and haw they should be handled. For
example, material crease (strength) was a problem which was investigated
thoroughly, and which resulted in a MIL specification for the testing of
materials generally and creases specifically. This specification covers
the use of Dacron material, which fits into practical aircraft experience.
The present construction technique, using a multiplicity of panels seamed
together, was admittedly a disadvantage; a technique which would eliminate
the seams would be welcome. The reason for the use of multiple panels was
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somewhat
hazy,
but it appears to have been done for two reasons - the first,
as a means for rip-stopping and, the second, for prevention of rotation of
the blimp body. (Note: diagonal strength is important in bodies of high
fineness ratio - this is one of the requirements we hope to reduce with our
lover fineness ratios.)
With regard to life of the blimp materials
pointed out that the
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present envelopes have been used as long as
years;
certainly, 6 years is
not too long. Ideally, the airships should be moored outside continuously r
this is now being done -4- 114'."4 'put not at (where there are adequate
hangaring facilities). pointed out that the life is a rough function
of fatigue characteristics of the material rather than the weathering charac-
teristics.
showed some curves on the relative sizes of a balloon of 1.5:1 ratio
gore as compared to 4.17:1 for equal volumes. The comparison was quite
was obvious. 7-nrahahl]mentioned that we had given some thought to the design
striking - th ease of maneuvering, especially in and out of hangars,
of a small airship to be used in conjunction with the submarine hunter-killer
mission of aircraft carriers. He stated that several ships could be carried
deflated in crates aboard a ship. Rapid inflation equipment could be designed
to reduce operatipnal difficulties, and the proposed shorter shape in a size
of 50,000 cu ft should not be difficult to handle. Perhaps the stern propulsion
unit, along with a gondola, could be attached to a gas bag considered to be
more or less expendable.
personnel mentioned that inflation in 30-40 knot wind would be necessary,
along with a 95 knot speed and a duration of 15-18 hours. Helicopters are
now liked because of their readiness factors, but they do have noise, fatigue,
and vibration problems. Helium storage aboard ships is a difficult problem
to cope with.
granite suggested was rather light on the materials aspects; Capt.
r-Than7suggested that the program we outlined was good but that it should
include more on the study of materials. Also, he suggested that the first
program be completed and reviewed before getting into the development models
to assure that the gains will be worthwhile.
asked a question about the objectives of the program we proposed.
These were listed as follows:
1. Payload - 400 lb
2. Altitude - 7,000 ft
3. Free ballooning capability - 2 hours
4. Cruise range - 100 miles (at Vmax)
5. Vmax - 50 knots
6. Operational capabilities - field inflatable in 15 knot wind;
volume approximately 25,000 Cu ft.
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It was pointed out that this was a specific task requiring modest performance.
Therefore, it does not give a true picture of the capabilities possible with
a plastic balloon utilizing the advanced techniques.
pointed out that there has been disinterest in vehicles at high
a they have slaw velocities since, as a correlarly, their maneu-
verability would be low. He did comment on the difficulties of enemy counter
actions above the 4ol000 ft altitudes.
mentioned that a solar powered stratospheric ship would be an
eventual goal to aim for and that three conditions were in favor of such a
development:
1. Large areas for the collection of the sun's energy
were available
2. At stratospheric heights there would be a minimum of
weather to content with; studies indicate that winds
are light in the 60,000-8o,000 ft altitude
3. Decreased temperature and increased radiation allow
a solar battery to operate much more efficiently;
(Demoreat has flown a solar battery on a stratospheric
balloon to demonstrate this effect)
A logical first step in this direction would be the carrying out of the pro-
gram entitled "Electrically Propelled Balloon", as previously described.
Research on the use of solar energy for this purpose should be initiated.
Ultimately large airships, perhaps carrying infrared detection equipment on
an operational basis could be designed. A study was made of the horsepower
required to maintain a station in the Mediterranean area during the months
of July and January for a family of airship sizes from 10,000 lb gross weight
to 50,000 lb gross 'weight. January is expected to be the worst month and
July the best. Figures 4, 5 and 6 indicate optimum altitudes and the follow-
ing maximum power requirements for the family of sizes considered:
July
January
Optimal Altitude
60,000 ft
75,000 ft
Maximum Power
Requirement Range
60 - 190 H.P.
6o - 360 H.P.
It was questioned whether could construct a balloon as described within
a year, and it was pointed out that the techniques used in plastic balloon
work differed from the standard blimp construction techniques and the ability
to move fast was one of the desirable features. Also, it was pointed out
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that, from the cost standpoint, the technique uses permits economical
construction fnmn temporary and easily changed tooling.
The meeting was adjourned, with general technical approval from on
the first year of the proposed program. Financial support of the program
was to be discussed later by
In the afternoon session, the participants were:
The conversation was limited to engineering discussions, mainly on materials,
design and fabrication techniques.
personnel showed a chart of the weight-strength characteristics of
materials, stating that the plastics appeared equal to coated synthetic cloths.
Whitnah stated that a combination of nylon and polyethylene (7 oz nylon, 2 oz
polyethylene) has a strength of 400 lb/in., a value much higher than those on
the BuAer chart.
Sealing of plastic materials was discussed with regard to the different
methods required for different plastics. Polyethylene, for example, is very
easy to seal because it has a fairly large tolerance in the range of sealing
temperatures; whereas, materials such as Saran are very touchy in this respect.
Generally, there is a reduction in the strength at the heat seal because of
the degradation (and loss of molecular alignment) due to the melting. Special
methods are available whereby these effects are minimized by rapid heating
and cooling while the films are physically held in juxta position.
Permeability or diffusion can be controlled through the use of a suitable
film and through proper sealing techniques. The occurrence of holes in the
film can be governed by the use of inspection techniques or, better yet,
through the use of laminated films. As an aside, the leakage problems at
altitude are less severe for the sane hole area than at sea level because
the mean free path of the molecules is longer and, consequently, fewer gas
molecules escape from the balloon. This factor would certainly be important
for long duration flights.
The heavy loads can be carried by balloons through the utilization of the
"Natural Shape". This is the scheme promoted by Professor Upson, the Uni-
versity of Minnesota, and , in which the shape is so made
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that the lateral stresses are minimized (theoretically going to zero) and all
the loads are taken in the longitudinal direction.
Gust velocities of 30-35 ft/sec must be considered in the design.
Reference was made to a report by a (formerly with Goodyear, now
with North American Aviation) on the ballonet design. The designs considered
in this report apparently were based strictly on the differential pressure
between the gas and the atmosphere (say 3/4 in. of water); and they did not
take into account the other perturbing factors which might be considered. Also,
a factor of safety of about 2 or 3 was applied (by. Goodyear) to assure complete
safety. This apparently is a standard practice with Goodyear.
Since stresses and strains are a function of both the loading and the time, a
means of establishing a working stress is to take the "quick-break" strength
of the fabric as 100% and then working at the 25% level as a working stress.
Actually, experience is at about 1/2 of the 25% level. For material testing
purposes, Goodyear uses a cylinder of material approximately 10 inches in
diameter, which is then inflated to failure.
The use of Dacron versus cotton materials was discussed. Recent tests were
made on cylinders (made of the above materials) of approximately 4 ft diameter
and 10 or 15 ft long for bending and torsional stresses. As a measuxe of the
elongation, the cotton material (at 19% of the ultimate stress) had 1/3 of the
elongation of the Dacron (at 17%_of the ultimate stress). This was true on
sone 2,000 test cy t 20% of the ultimate stress, the elongations tend
to become closer. now has a program to get data at the 35% level; how-
ever, no results are ye available. They are expected to become available in
about six months.
In answer to a question regarding the use of many individual segments of
materials in the construction of present blimps, it was indicated that if
they were all in the same direction it would give a twist to the balloon.
The application is therefore not for rip-stop purposes. It was once proposed
that a balloon be made of a single sleeve of material; however, a special
loom would be required and this was not economically feasible.
The measurement of stresses in D astic structures are to be measured (in a
current program at using a vibrating mass system to give mate-
rial tension.
The penumatic beam technique can be used in the empennage of plastic balloons.
The equation used to determine the strength of the cantilever beam is given as:
Fl = K 6P WB AB #E1
CONFIDENTIAL
Declassified in Part - Sanitized Copy Approved for Release 2012/06/14: CIA-RDP78-03642A001300040017-5
Declassified in Part - Sanitized Copy Approved for Release 2012/06/14: CIA-RDP78-03642A001300040017-5
CONFIDENTIAL
To:
-13- March 7, 1958
where: the factor K is a function (of the tangent) of the angle of deflection,
e. This function shows a light decrease of E: with increase in e9 .A is the
width of the base, AB is the area of the base, andi is the deflection term.
A Goodyear study on the wrinkling of balloons in flight showed that approxi-
mately 1-1/2 times the stress at the start of wrinkling is required to reach
the ultimate (critical).
Mayer' s earlier work in the blimp program apparently involves a study of the
deflection equations, and he indicated that there was a gain in strength in-
versely as the 4/31s power of the fineness ratio.
The final discussion was on how we would control the balloon. The proposal
was indefinite on this point and had therefore raised questions in the minds
of the BuAer people. They were particularly interested in the mechanisms
whereby we proposed to do the controlling d iso on what our basic design
criteria was. This, it was pointed out by ople, would come out of the
study program. Several methods were mentione one of which will probably be
used in the preliminary design.
Copies to:
CONFIDENTIAL
Declassified in Part - Sanitized Copy Approved for Release 2012/06/14: CIA-RDP78-03642A001300040017-5
Declassified in Part - Sanitized Copy Approved for Release 2012/06/14: CIA-RDP78-03642A001300040017-5
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Declassified in Part - Sanitized Copy Approved for Release 2012/06/14: CIA-RDP78-03642A001300040017-5
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Declassified in Part - Sanitized Copy Approved for Release 2012/06/14: CIA-RDP78-03642A001300040017-5
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