US3661087A

US3661087A - Flare deployment system

Info

Publication number: US3661087A
Application number: US884084A
Authority: US
Inventors: Robert C Willard; Harold L Dauer; Ronald Clifford Noles
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1969-12-11
Filing date: 1969-12-11
Publication date: 1972-05-09
Anticipated expiration: 1989-05-09

Abstract

The deployment of a hot air suspended flare system is enhanced by a time delay venting and destruct system. As the balloon is deployed with the aid of a drogue chute, a lanyard attached to the chute extracts a safety wire from a firing device which ignites a length of safety fuze proportioned to ignite a first segment of stranded propellant after a predetermined time for cutting a vent in the balloon and at the same time igniting a second proportioned length of safety fuze. The second length of safety fuze, in turn, ignites a second pattern of stranded propellant which completely destroys the lifting power of the balloon.

Description

51 3,661,087 I451 May 9,1972

United States Patent Willard et al.

[54] FLARE DEPLOYMENT SYSTEM 3,411,401 11/1968 Harris.............,.... 3,172,330 3/1965 Lidmalm et 211...... 3,135,163

[72] inventors: Robert C. Wlllard, China Lake; Harold L.

6/1964 Mechlin, Jr. et al.

Dauer; Ronald Clifford Noles, both of Ridgecrest, all of Calif.

3,302,906 2/1967 Winker........,....... .....244/32 3,478,687 11/1969 Craig...................

[73] Assignee: The Unlted States of America as Primary Examiner-Samuel W. Engle represented by the Secretary of the Navy Dec. 11, 1969 Attorney-R. S. Sciascia, Roy Miller and Gerald F. Baker [22] Filed:

ABSTRACT The deployment of a hot air suspended flare system is enhanced by a time delay venting an [21] Appl. No.: 884,084

d destruct system. As the balloon is deployed with the aid of a drogue chute, a lanyard attached to the chute extracts a safety wire from a firing device which ignites a length of safety fuze proportioned to ignite a first segment of stranded propellant after a predetermined time for cutting a vent in the balloon and at the same time igniting a second proportioned length of safety fuze. The second length of safety fuze, in turn, ignites a second pattern of stranded propellant which completely destroys the lifting nm n fill g 2 M 0% ..4 1 29 v 418 R I51 35 7 n 14 P m m .4

N34 5 W22 T R m7 W o u T. 7 d l u e A 2 "m h P w C S m m m m m n A U e u r T m m. h S u n e m I R m m Tu W m M N m m& U n r H mm U .m n um m 0 mm H u h F g n i W a -l D 6 M m C o 1 d b e h n 0 r e W O p 7 mm mm 21. 0

2,675,882 4/1954 Bazzonietal..... 2,708,409 5/1955 Borcher........,....

PATENTEIJMAY 9 I972 SHEET 2 OF 2 Zinnnnnnnn QDU UDD FIG. 4

FIG. 3

FIG. 5

WEIGHT l l -VENT| N G |4-DESTRUCT LIFT INVENTORS ROBERT C. W/LL A R0 HAROL D L. BAUER RO/VAL 0 C. IVOL E5 5) Roy Mill er 4 TTOR/VEY Gerald E Baker AGE/V7 l I I00 I50 200 DEPLOYMENT TIME (SECONDS) FLARE DEPLOYMENT SYSTEM CROSS REFERENCE TO RELATED APPLICATIONS The disclosed method and apparatus was developed as a part of the illuminating flare system more fully disclosed in U.S. application Ser. No. 683,095, filed Nov. 8, 1967 and now US. Pat. No. 3,478,687 issued Nov. 18, 1969, the subject matter of which patent is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION In an effort to prolong the useful life of aerial flares, a hot air balloon device has been substituted for the usual parachute. As the hot air balloon suspended flare burns, the ratio of flare weight to balloon lift decreases to a point where the system begins to rise. Since illumination varies inversely as the square of the distance, any appreciable rise of the system is undesirable. Also, after the flare has completely burned out, it is desirable to remove the balloon from the air for aircraft safety.

The venting and destruct system according to the present invention is designed to cut a vent in the balloon at a predetermined time after deployment to check the ascent of the system and thereafter to completely destroy the remaining lift of the system at a time closely coinciding with flare burnout.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING FIG. I is a polar projection of a deployed balloon incorporating the invention;

FIG. 2 is an enlarged view partly in section of the ignition means indicated at A in FIG. 1;

FIG. 3 is a detail view partly in section of the ignition device;

FIG. 4 is a detail view partly in section of a first fuze, propellant strand junction;

FIG. 5 is a detail view partly in section of a second fuze propellant strand junction; and

FIG. 6 is a graphical illustration of system operation.

DETAILED DESCRIPTION OF THE INVENTION The destruct system 10 is shown schematically illustrated on a plan view of a deployed balloon 12 in FIG. 1. The ignition device which initiates operation of the system is indicated in circle A of FIG. 1 and is shown in more detail in FIG. 2.

Connected between ignition device A and junction B is a measured length of safety fuze 24 having a burn time of 220 t seconds. Between junction 8 and junction E the length of safety fuze 34 is proportioned to burn 80 t 10 seconds. Total burn time of

fuzes

24 and 34 should not exceed 330 seconds.

A T-fitting 30 (see FIG. 4) is placed at junction B and a length of propellant strand 28 is threaded through seams of the balloon, looped at C and threaded through a further seam to point D.

The safety fuze 34 terminates in the vicinity of junction E in a coupling 40 (FIG. 5) and therefrom a length of propellant strand 48 is threaded through balloon seams in a manner similar to 28 above. Loops are formed at suitable intervals in placing the

strands

28 and 48 to prevent breakage when the balloon blossoms.

The system is actuated by a primer cap (see FIG. 3) struck by a spring plunger 20 when freed by removal of safety wire 14. As shown in FIG. 2, safety wire 14 is passed through a hole in the outer end of firing pin 16 of igniter l9 and a lanyard 18 is attached to loop 14, the other end of lanyard 18 being attached to a drogue chute which is designed to pull the balloon out of its package. In practice, the cable 14 is severed in the balloon packing process at a point indicated by dotted line 15 so that, when the drogue chute has fully extended the balloon,

further pull of the drogue chute will remove cable 14 from firing pin 16 allowing it to be projected by spring 20 against primer means 22, thus i iting the safety fuze segment 24.

Safety fuze segment 5 is cut of sufiicient length to take approximately 240 seconds to burn down the intersection with the stranded propellant section 28 shown in FIG. 3. The T- shaped fitting 30 is crimped onto the first safety fuze segment 24 and on the second safety fuze segment 34 in line therewith. At right angles to the strands of safety fuze the fitting is fastened to a length 28 of stranded propellant 28 which is layed out in the seams of a gore of the balloon so that a right angled vent is cut in the balloon when the propellant strand 28 is ignited.

The segment 34 of the safety fuze is dimensioned for about a 30 second time delay before the main destruct strand is ignited. Safety fuze segment 34 ignites the main destruct propellant strand 48 through a fitting 40 as shown in FIG. 4. Propellant strand 48 burns rapidly up one gore, around the second tiered hem of the balloon and ignites two further segments as shown in FIG. 1, to completely destroy the lift of the balloon.

To determine the desired lengths of fuze segments 24 and 34 a roll of safety fuze (approximately 50 feet) is unrolled and a 1 foot piece is cut from each end. These pieces are burned and the burn time averaged to approximate the average burn time/foot of the roll (approximately 45 sec/ft).

In FIG. 5, the venting and destruct times are shown in relation to the plot of balloon lift and system weight during deployment. As the system is released from the aircraft, system weight is at a maximum and balloon lift is nil. The jettisoning of fairings and fittings and the rapid burning of the heat generator cause a rapid weight loss in the first few seconds of deployment time and thereafter weight decreases fairly linearly as the flare candle is consumed until minimum weight is attained at candle burnout.

Within several seconds after deployment the balloon blossoms and begins to gain in lift as air within is heated by the heat generator. Maximum lift occurs only shortly after the heat generator is consumed. Thereafter lift approaches zero in an asymptotic fashion and the system drifts slowly earthward as lift falls below weight. At about 240 seconds, however, weight is diminishing faster than lift and the system at this point would rise appreciably were it not for the venting according to the present invention.

What is claimed is:

1. Pyrotechnic control means for deployment of a hot air balloon or the like having a plurality of segmental fabric gores joined by felled seams, said control means comprising:

first and second measured lengths of safety fuze;

means for timely ignition of the first of said lengths of safety fuze;

first and second measured lengths of propellant strand serially connected to said lengths of safety fuze;

ignition of said first of said lengths of safety fuze resulting in substantially simultaneous ignition after a predetermined time of said second length of safety fuze and said first measured length of propellant strand; and

ignition of said second length of safety fuze resulting in ignition after a predetermined time of said second length of propellant strand;

said lengths of safety fuze being threaded in spaces formed by selected ones of said seams; and

said lengths of propellant strand being arranged in a first smaller pattern and a second larger pattern respectively; so that, when said first length of propellant strand is ignited after the time delay inherent in said first safety fuze, a small hole is cut in said fabric; and when said second length of propellant strand is ignited, after a time delay inherent in said second safety fuze, a second hole is cut in said fabric such that all lift of said balloon or the like is effectively eliminated.

Claims

1. Pyrotechnic control means for deployment of a hot air balloon or the like having a plurality of segmental fabric gores joined by felled seams, said control means comprising: first and second measured lengths of safety fuze; means for timely ignition of the first of said lengths of safety fuze; first and second measured lengths of propellant strand serially connected to said lengths of safety fuze; ignition of said First of said lengths of safety fuze resulting in substantially simultaneous ignition after a predetermined time of said second length of safety fuze and said first measured length of propellant strand; and ignition of said second length of safety fuze resulting in ignition after a predetermined time of said second length of propellant strand; said lengths of safety fuze being threaded in spaces formed by selected ones of said seams; and said lengths of propellant strand being arranged in a first smaller pattern and a second larger pattern respectively; so that, when said first length of propellant strand is ignited after the time delay inherent in said first safety fuze, a small hole is cut in said fabric; and when said second length of propellant strand is ignited, after a time delay inherent in said second safety fuze, a second hole is cut in said fabric such that all lift of said balloon or the like is effectively eliminated.