United States Patent (19) 11 4,132,170

Hardy et al. 45 Jan. 2, 1979

(54) FUEL-AIR TYPE BOMB 2,445,312 7/1948 Cooke et al. ............................. 102/6
t ep 2,742,856 4/1956 Fieser et al. ............................. 102/6
(75) Inventors: Periam B. Hardy; Lewis L. Gay; 3,208,891 9/1965 Eschrich et al. ... ... 149/89 X
Erd L. Husler, all of Boulder, 3,377,219 4/1968 Stiefel et al. ........................... 149/89
OO. 3,499,384 3/1970 Zernow et al. .......................... O2/6
- 3,505,957 11/1970 Tich
tal. ....................... 102/6
73) Assignee: Beech Aircraft Corporation, Wichita, '7' E.C. 85%
Kans, 3,596,602 8/1971 Gey et al... . . 102/90
2 1) Appl. No.: 115,119 3,596,603 8/1971 Gryting as a as a sa & a a sa A a so a sas a aa 102A6

22 Filed: Feb. 12, 1971 E.

torney, Enlaid
l, irn- H. Brown
L. B , Jr.
51 Int. C.? ............. w w a as a a as a F42B 25/12 rney, Agent, or Firm-Edward L. Brown, Jr
52 U.S. C. .......................................... 102/6; 102/66; 57 ABSTRACT
102/90 a 8
58) Field of Search ......................... 1026, 39,66. Amally
fiel-air type bomb with
non-explosive, whicha contains
bursting aiquid fueling
charge centrall
149/89-91 located within the fuel; the bursting
(56) References Cited shocks the fuel into a highly reactive mixture with the
U.S. PATENT DOCUMENTS ising air while simultaneously disseminating the
1,287,372 12/1918 McGaw ................................. 102/66 s
uel at aO supersonic rate over a large area, which causes
2,195,965 4/1940 Holm .......... "o increasing blast effects.
2,372,264 3/1945 Firth ........................................ 102/6
2,445,311 7/1948 Cooke et al. ........................ 102/6 X 13 Claims, 2 Drawing Figures

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8.
U.S. Patent Jan. 2, 1979 4,132,170

17

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INVENTOR.
 4,132,170 2
1.
outward into the air, culminating in a large fire ball. The
FUEL-ARTYPE BOMB overpressure effect of the explosion on the target area is
equally devastating as the previously mentioned two
This invention relates to aerially delivered destruc event FAE.
tive bombs in general, and more particularly to a bomb 5 In the prior art two event FAE devices there was
which will herein be referred to as a fuel-air mixture much concern about the burster charge causing the fuel
type bomb, as opposed to a bomb, the explosive power to preburn before the second event of detonation. This
of which is provided by a concentrated highly explosive is of no concern in the present invention since the
material not dependent upon an outside source of oxy burster charge shocks the fuel to a sufficient degree to
gen. The conventional high explosive bomb has a de 10 cause immediate detonation as the fuel is dispersed. The
structive effect over only a very limited target surface present invention will not function under static firing
area, whereas the fuel-air bomb has a destructive effect conditions with the presently used burster charges since
over a much greater surface area. the fuel needs the additional dispersing effect of air
pressure breaking up the fuel to obtain enough oxygen
BACKGROUND OF THE INVENTION 15 for complete detonation. While the liquid fuels used are
Certain Government Agencies and their contractors called monopropellants, they normally need some addi
have in recent years produced and tested fuel-air type tional oxygen assistance or increased pressures and
bombs, also known as FAE devices, all of which have temperatures for detonation.
had critical disadvantages. The early bombs tested have The single event FAE bomb eliminates any separate
carried either pressurized propane or ethylene oxide as 20 time delayed detonators or their related structure. Con
fuel to provide the ultimate explosive effect, when trary to the previously mentioned two event FAE's, the
mixed with air. The fuel was dispersed into the air by greater the terminal velocity of the single event bomb,
means of a high brisance explosive. Fuel dispersal by the more damaging the effect of the explosion.
means of a high brisance explosive resulted in the for At the forward end, the bomb housing carries a se
mation of a doughnut shaped cloud of fuel-air mixture 25 quence initiating proximity fuse of any desired type,
which cannot be efficiently detonated by detonators connected by prima cord or electrical detonator extend
located in its void central area. For this reason such ing well into the burster explosive in the central cham
bombs necessarily have had to carry numerous cloud ber.
detonators, together with a means for distributing these When the bomb closely approaches the target the
detonators into various locations within the surround 30 proximity fuse is activated, igniting the bursting charge
ing doughnut shaped cloud prior to actuating the deto which ruptures the walls of the housing dispersing the
nators. Since the downward velocity of travel of the fuel into on-rushing air with a sufficient shock to deto
bomb hardware, after fuel dispersal, is much greater nate the fuel at the same time.
than that of the doughnut shaped cloud, it has not been It is therefore the principal object of the present in
possible to properly distribute the detonators into the 35 vention to provide a single event fuel-air explosion. A
doughnut shaped fuel-air mixture without retarding the further object is to provide a FAE bomb with no termi
terminal velocity of the bomb. By reason of this limita nal velocity limitations.
tion, the bombs must use a parachute or other speed An additional advantage is the use of a liquid fuel
retarding device prior to target impact. which is non-gaseous and stable at standard tempera
Such parachute lowered bombs are subject to wind tures and pressures, thus eliminating the necessity of a
drift, enemy detection and dispersal prior to bomb deto pressurized fuel chamber.
nation, hanging up in the trees, etc. Our invention will be more clearly understood when
Another type of two event FAE device, covered in the following description is read in connection with the
our U.S. patent application Ser. No. 89,140, utilizes a accompanying drawings, in which:
low brisance central burster explosive with an unpres 45 FIG. 1 is a central longitudinal sectional view though
surized monopropellant liquid fuel which is stable in the a bomb embodying our invention; and
liquid state but highly explosive when atomized in the FIG. 2 is a transverse sectional view of the same,
air. By using a low brisance burster charge the cloud taken along the plane indicated by the line 2-2 in FIG.
formation is not torus shaped but rather hemispherical 1.
with a substantially uniform fuel-air density. With a 50 Referring to FIG. 1 of the drawings, the illustrated
uniform cloud the second event detonation can be han preferred embodiment of our invention includes a load
dled with a single or dual detonator rather than the carrying housing designated as a whole by the numeral
complex multiple detonator system previously men 10. A combination nose cone and fuse supporting mem
tioned. ber, designated as a whole by the numeral 11, is suitably
55 secured to the forward end of the housing 10. A tail
SUMMARY OF THE INVENTION assembly rigidly secured to the aft end of housing 10 is
Prior to the present invention it has been felt that to blydesignated as a whole by the numeral 12. The tail assem
achieve a fuel-air explosion, you must first dispense the 12 supports a plurality of outwardly spring pressed
fuel in an aerosol cloud before the second event of retractable stabilizing fins 13.
detonation. The present invention has achieved a fuel 60 Housing 10 includes a rigid circular end plate 14 at
air explosion without the second event, under dynamic one end and a circular rib 15 at its opposite end. Con
conditions. The burster explosive (first event) not only centric cylindrical walls 16 and 18 have their opposite
dispenses the fuel into the atmosphere but simulta ends secured to the end plate 14 and nose cone 11 in
neously begins the detonation of the fuel at a supersonic sealed, leak tight relationship, as by welding or other
rate. Detonation at a rate less than supersonic causes the 65 means. The two walls thus define two separate, concen
fuel to burn with no blast effect. What in effect happens, tric sealed chambers 19 and 20. The inner wall 16 can be
is an expanding fuel-air explosion is caused which constructed of materials other than aluminum such as
spreads in size from time zero pushing the burning fuel plastic, stainless steel, and brass. When utilizing certain
 4,132,170
3 4.
burster explosives that can be placed directly in the fuel, detonator holding screw within the fuse 28 and retrac
the inner wall 16 can be eliminated. While the drawings tion of the screw permits a stab pin detonator to be
only illustrate a centrally positioned burster explosive, spring rotated into alignment with an impact firing pin
an implosion type of charge could also be used which in the fuse. This completes safe arming of the fuse firing
would surround outer wall 18. 5 circuit after the bomb has left the carrier. Details in the
An elongated rigid stiffener and swaybrace 22 is se construction of fuse 28 are not shown and are not con
cured longitudinally to the exterior surface of outer sidered necessary because they are well known to those
housing wall 18, as shown. On its outer surface stiffener familiar with this art, and the specifications for the
22 carries lugs (not shown) and fixed, fore and aft M158 fuse are fully disclosed in Army Manual TO 11A
aligned eyelets 23 and 24 which serve as guides for a 10 1-31 OP1664 (Vol. 2)-PP471-473. Furthermore, almost
fuse arming lanyard 25. any type of military qualified proximity fuse can be used
The forward end of the nose cone 11 centrally carries with this bomb, as previously explained.
a rigidly fixed, internally threaded fitting 26, which As the bomb during its free fall approaches the target,
receives and supports the inner end of a tubular fuse fuse 28 makes target impact before housing 10 reaches
support 27. A conventional proximity fuse 28 is fixed on 15 the target proper. Impact of the fuse 28 forces the fuse
the forward outer end of the support 27. firing pin into the stab detonator within the fuse. The
The fuse illustrated is a standard stab detonator type, detonator fires and sends an explosive shock wave
identified by the Department of Defense (Army) as an along the prima cord 29 into the central burster charge
M158 fuse. Its operation is well known in the art. The in chamber 19 and fires that explosive.
fuse illustrated can be classed as a proximity fuse be 20 Explosion energy is transmitted to the liquid fuel in
cause it is positioned ahead of the nose of the bomb, and chamber 20. The hydrostatic pressure generated by the
it is detonated by impact before the bomb housing actu central burster explosion ruptures and shatters the walls
ally contacts the target. of both chambers 19 and 20, and disperses liquid fuel
Furthermore, the fuse support 27 may be eliminated particles into the onrushing surrounding air. At the
and an entirely different type of proximity fuse secured 25 same time the shocking effect of the explosion energy
to the nose cone. Other suitable fuses are the Radar
Proximity Fuse Mark 43 TDD, the Infra-Red Air Prox begins to detonate the fuel, and as the fuel detonates, it
imity Fuse, or the omni-directional, stab pinpercussion expands the size of the exploding fuel until there is
complete detonation of all the fuel. The time interval
cap, explosive train fuse FMU 68, all of which are in for
common use by the Department of Defense, and are of 30 detonation is approximiately 10 milliseconds as com
well known construction. pared with to 2 milliseconds for an H.E. bomb.
Regardless of the type of fuse needed, the explosive Tests show that complete detonation of the fuel gen
element of the fuse is connected to a length of prima erates a shock wave which produces an overpressure of
cord 29, which extends through fuse support 27, 300 psi radially outward 10 feet from hardware impact
through fitting 26, and well into a body of explosive 35 point, 200 psi radially outward 20 feet, and 100 psi radi
with which chamber 19 is packed. The inner end of the ally outward 30 feet.
prima cord fuse train is designated by numeral 30. Tests show that complete detonation of the fuel also
The explosive burster charge utilized in chamber can generates an extremely high overpressure in a down
be any type of explosive in a sufficient amount to create ward direction. Calibrated crush indicators, rupture
a supersonic detonation of the fuel; as for example 4 lbs. 40 discs, gauges, piezo-electric shock transducers, and
of Nitroguanidine are required to detonate 265 lbs. of other diagnostic equipment set in deep fox holes, cov
Normal Propyl Nitrate (NPN). While both low or high ered bunker arrays, etc., have shown terminal effects
brisance explosives can be used, the explosive Ni equal to or greater than target damage at ground level
troguanidine, considered a borderline high brisance and above. This extreme downwardly directed over
explosive, has been very successful. Any high explosive 45 pressure can only be explained by theory. The time
that has a shock output equivalent to 4 lbs. of Ni interval of the overpressure is substantially greater than
troguanidine will function with the presently used fuels with conventional high explosive bombs, therefore the
and bomb containers. If the thickness of bomb wall 18 damage effect is greatly increased.
were increased, the same shocking effect could be In summary, the above described invention provides
achieved with a less amount of explosive. SO a bomb which is so constructed that it utilizes a rela
The fuels which have been successfully used include tively safe, normally non-explosive, normally liquid,
Normal Propyl Nitrate (NPN), Ethyl Propyl Nitrate unpressurized rocket fuel to produce a long pulse
(EPN) and mixtures of both (58%-60% C2H5NO3 and highly destructive terminal effect on targets; a bomb
from 40%-42% CHNO3). Any other liquid fuels of which simultaneously forms and detonates fuel-air mix
the class which are non-gaseous and stable at normal 55 ture under dynamic conditions without any terminal
temperatures and pressures but when dispersed in the velocity limitations.
air become highly explosive could be used. Having described the invention with sufficient clarity
to enable those familiar with this art to construct and
OPERATION use it, we claim:
When the described bomb is mounted in a bomb rack, 1. An aerial dropped FAE ordinance device compris
eyelet 46, through which arming lanyard 25 is threaded, 1ng:
is connected to the rack. a fuel container;
When the bomb rack is actuated to jettison the bomb, a nitrated organic monopropellant liquid fuel filling
secured eyelet 46 pulls aft on lanyard 25, which is con the container;
nected to slide pin 47 of fuse 28, and pulls pin 47, out of 65 explosive means integral with the container and fuel;
its propeller blocking position. Free fall of the bomb proximity fuse means supported on the container for
causes air driven propeller 48 of fuse 28 to spin. A pre detonating the explosive means in a dynamic envi
determined number of propeller revolutions retracts a ronment;
 4,132,170
5 6
said explosive means being of a sufficient energy level ing of the liquid fuel in an atomized form into the
to disseminate the fuel into the dynamic atmo dynamic atmospheric environment and
spheric environment in the atomized form and to detonating the fuel in the atomized form from time
supersonically detonate the fuel in the atomized zero with respect to the atomization thereof,
form from time zero with respect to the atomiza
5 thereby having no time delay between the atomiza
tion thereof, thereby having no time delay between tion and detonation of the liquid fuel.
8. A method of creating a fuel-air explosion as set
the atomization and detonation of the fuel. forth in claim 7, wherein the impact valocity of the
2. An aerial dropped FAE ordinance as set forth in confined quantity of fuel is no less than 450 FPS or
claim 1 wherein the liquid fuel is selected from the O greater than 1100 FPS.
group consisting of ethyl nitrate, normal propyl nitrate, 9. A method of creating a fuel-air explosion as set
and a mixture of ethyl nitrate and normal propyl nitrate. forth in claim 7, wherein the confined quantity of fuel is
3. An aerial dropped FAE device as set forth in claim gravity dropped in a bomb shaped container at impact
velocities of no less than 400 FPS.
1, wherein the fuel is Normal Propyl Nitrate. 15 10. A method of creating a fuel-air explosion as set
4. An aerial dropped FAE device as set forth in claim forth in claim 7, wherein the confined quantity of fuel is
1, wherein the fuel is Ethyl Propyl Nitrate. gravity dropped in a bomb shaped container at impact
5. An aerial dropped FAE device as set forth in claim velocities of no less than 450 FPS, and the fuel is inter
1, wherein the explosive means is Nitroguanidine. nally shocked by the explosive means which is centrally
6. An aerial dropped FAE device as set forth in claim 20 positioned within the container.
1, wherein the fuel is a mixture of normal propyl nitrate 11. A method of creating a fuel-air explosion as set
and ethyl propyl nitrate. forth in claim 7, wherein the fuel is Normal Propyl
7. A method of causing a fuel-air explosion compris Nitrate.
ing the steps of: 12. A method of creating a fuel-air explosion as set
placing a container having therein a nitrated organic 25 forth in claim 7, wherein said explosive means is ignited
monopropellant liquid fuel, a proximity fuse and an by a proximity fuse immediately above the target.
13. A method of creating a fuel-air explosion as set
explosive in a dynamic atmospheric environment; forth in claim 7, wherein said explosive means is Ni
shocking the fuel upon detonating the explosive with troguanidine.
a sufficient energy level to thereby cause dispens 30

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