US3736836A

US3736836A - Launching pad assembly for miniature rockets

Info

Publication number: US3736836A
Application number: US00164523A
Authority: US
Inventors: J Mcallister
Original assignee: CENTURY ENG
Current assignee: CENTURI ENGINEERING CO INC US; CENTURY ENG; Toray Industries Inc
Priority date: 1971-07-21
Filing date: 1971-07-21
Publication date: 1973-06-05
Anticipated expiration: 1990-06-05

Abstract

A launching pad assembly having an upright launching rod for releasably supporting a miniature rocket during the initial flight phases of ignition and liftoff. The launching pad assembly base has spaced support legs adjustable to launch the rocket at a predetermined angle to the ground. The assembly further includes a pneumatically operated electrical ignition system to activate the igniter of the miniature rocket with a minimal power supply operable at a position remote from the rocket. A safety key is provided which concurrently indicates continuity of the electrical system and prevents accidental activation of the igniter.

Description

United States Patent McAllister 51 June 5, 1973 541 LAUNCHING PAD ASSEMBLY FOR 2,785,852 3/1957 Bramming ..417/437 MINIATURE ROCKETS 2,421,893 6/1947 Lambert et al. .....89lli8l4 X ,838,629 6 1958 h s1 [75] Inventor: Jack G. McAllister, Minneapolis, 2 Panzen 200/ H Primary Examiner-Samuel W. Engle [73] Assignec: Centuri Engineering Company, Inc., Att0rneyEric P. Schellin and John A. Robertson Phoenix, Ariz. 22] Filed: July 21, 1971 [57] ABSTRACT {21] APPL 164,523 A launching pad assembly having anupright launching rod for releasably supporting a mmiature rocket dur- 7 ing the initial flight phases of ignition andflliftoff! The,

U-S- Cl. ..89/1-814, B, launching pad assembly base has paced upport legs 200/81 H adjustable to launch the rocket at a predetermined [51] Int. Cl. ..F4lf 3/04 angle to the ground The assembly further includes a {58] Field of Search ..46/74 A, 74 B; pneumatically operated electrical ignition System to 417/437,200/81 H, 89/ -8, activate the igniter of the miniature rocket with a L815 minimal power supply operable at a position remote from the rocket. A safety key is provided which con- [56] References Cited currently indicates continuity of the electrical system UNITED STATES PATENTS and prevents accidental activation of the igniter.

1,076,091 10/1913 Allen ..200/81 H 8 Claims, 9 Drawing Figures PATENTEDJUN 5 I973 SHEET 10F 5 INVENTOR.

JACK 6. MC ALLISTER I sa-5-1 ATTORNEYS PATENTEDJUH 51975 3,736,836

SHEET 2 [IF 5 JACK G. MC ALLISTER ATTORNEYS PATENTEUJUH 5 I973 SHEET 3 BF 5 INVENTOR.

JACK 6. MC ALLISTER ATTORNEYS PATENTEDJUH 5 I975 3.736.836 SHEET u 0F 5 ATTORNEYS PATENIEUJUH 5 I975 SHEET 5 OF 5 INVENTOR.

JACK 6. MC ALLISTER ATTORNEYS LAUNCI'IING PAD ASSEMBLY FOR MINIATURE ROCKETS This invention relates to miniature rocketry.

More specifically, the invention relates to a novel launching pad assembly adapted to releasably support a miniature rocket during the initial flight phases of ignition and liftoff.

In another respect, the invention concerns a miniature rocket launching pad assembly having an integral electrical system adapted to operate with a minimal power supply for activating the igniter of the rocket and incorporating novel means for controlling the electrical system at a position remote from the rocket.

In yet another aspect, the invention relates to a novel launching pad assembly utilizing a unique safety key for determining continuity of the electrical ignition system and preventing accidental activation thereof.

Since the beginning of the space age, miniature rocketry has steadily increased in popularity and today embraces many fields of endeavor. At the vocational or professional level, miniature rockets are utilized for meteorological surveys, photographic missions, and as a communications media. At the instructional level, miniature rockets are widely used for aeronautical research and the study of the related fields of science and physics. As an avocation encouraged by the National Aeronautics and Space Administration, miniature rocketry appeals to many enthusiasts. It is estimated that model rocketeers have launched more than million miniature rockets.

Each miniature rocket requires a launching system to facilitate flight. Essentially, the launching system comprises a platform, commonly called a launching pad, designed to releasably support and stabilize the rocket during the initial flight phases of ignition and liftoff, and an electrical system to activate the igniter which fires the rocket engine. Ironically, while rocket technology has developed at an accelerated pace, the development of launching systems has not kept stride.

Generally, launching systems for miniature rockets consist of two basic types. The first utilizes a relatively light-weight launching pad and a completely separate non-related electrical ignition system. In this configuration, the launching pad may or may not employ means for angular adjustment of the rocket relative to the ground. The second configuration utilizes a large bulky launching pad specifically designed to house the necessarily substantial battery pack. The type is usually devoid of angular adjusting means. In both cases, the electrical ignition systems are analogous, and consist of generally similar elements.

General safety recommendations require that the rocketeer or rocket launch operator be positioned at a minimum distance of 10 feet from the miniature rocket. However, a distance of 50 to 100 feet is generally considered superior and provides a better view of the rocket launch and flight. The rocket launch operator is provided at his remote station with a launch panel. The launch panel generally contains an electrical system activation or firing button, a light to indicate continuity of the electrical system and a key operated electrical switch to selectively engage either the firing button or the continuity light into the electrical ignition system. The primary function of the key switch is that of a safety to prevent accidental discharge of the rocket when the rocketeer is within unsafe distance of the rocket as, for example, when making last minute adjustments or installing the igniter. Due to the remote position of the launch panel from the miniature rocket to be launched and the necessary length of the electrical leads to connect between the panel and the rocket, the necessity for an outsized battery pack becomes readily apparent. The resistance in electrical leads of this length dictates that a large power supply, generally a six or twelve volt automobile battery, is necessary to provide adequate electrical energy to activate the igniter of the rocket.

The above-described typical prior art miniature rocket launching system is uneconomical and ungainly for several reasons. First, the rocketeer is required to purchase an expensive power supply and a launch panel incorporating expensiveelements, particularly the key operated electrical switch. Secondly, he is required to make numerous electrical connections and lay out an elaborate firing system at the launch site. Further, these systems provide little in convenience and compact stowage.

It would be highly advantageous, therefore, to provide a launching pad assembly for miniature rockets of substantially reduced weight and bulk, sufficiently convenient to operate and relatively economical to manu facture and utilize.

It is, therefore, an object of the present invention to provide an improved launching pad assembly for miniature rockets.

Another object of the invention is to provide an improved launching pad assembly having an integral electrical ignition system adapted to activate the igniter of a miniature rocket with a minimal power supply.

Still another object of the invention is to provide a launching pad assembly that is relatively lightweight, compact and readily stowable.

Yet another object of the invention is to provide a launching pad assembly that is particularly adapted for ease and convenience in field erection.

A further object of the invention is to provide a launching pad assembly of the above type which is adjustable to launch a miniature rocket at a predetermined angle to the ground.

These and other, further and more specific objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description thereof taken in conjunction with the drawings in which:

FIG. 1 is a perspective view of a launching pad assembly, constructed in accordance with the teachings of the present invention, with a miniature rocket in place and ready for launching;

FIG. 2 is a plan view of the rocket launching pad as sembly of the present invention;

FIG. 3 is a side elevation view of the device of FIG.

FIG. 4 is a front elevation view of the apparatus of FIG. 2;

FIG. 5 is a partial elevation view in section taken along the line 5-5 of FIG. 3 and specifically detailing the pivotal adjusting and mounting means of one leg thereof;

FIG. 6 is an isometric view partly in section of the electrical ignition system activator used in connection with the deviceof the present invention;

FIG. 7 is an isometric view of a combination safety key and continuity indicator specifically used in connection with the device of FIG. 1;

FIG. 8 is an elevation view in section taken along the line 8-8 of FIG. 2 and especially detailing the electrical ignition system incorporated within the launching pad assembly of the present invention; and

FIG. 9 is a plan view in section taken along the line right launching rod for releasably engaging the launching lugs of a miniature rocket and directionally stabilizing the rocket during the initial flight phases of ignition and liftoff. An exhaust deflector, preferably constructed of metal or other heat resistant material and having a first panel with a aperture therein to pass the launching rod and a second panel depending downwardly therefrom over the edge of the base, protects the launching pad from the hot exhaust gases of the rocket during the initial flight phases.

Triangular spaced support legs depend from the base and provide means for adjusting the base and concurrently the launch angle of the rocket in two planar directions about normally horizontal intersecting axes. A first leg is pivotally attached about an axis perpendicular to one of the intersecting axes in one direction and horizontal in the opposite direction. The second and third legs are pivotally attached about an axis perpendicular to the second axis in one direction and disposed at an angle from the vertical in the opposite direction. Adjustment of the first leg about its pivotal attachment alters its effective vertical height and therefore rotation of the base about the second of the two intersecting axes. Manipulation of the second and third are analogous. However, these legs effect the rotation of the base about the first of the axes.

In addition to providing changes in the launch angle of the rocket, the adjustable legs also may compensate for a vertical launch on uneven terrain. The second and third legs are provided with stops to limit their arcuate motion in the forward direction such that both legs will lie in a single plane perpendicular to the first of the axes and thereby have equal effectual length to expedite the vertical alignment on level terrain. The second and third legs are interchangeable within their respective pivotal mounting attachments to the base and are foldable, in the rearward direction, alongside the base for compact stowage of the launching pad. To enhance this arrangement, the first leg may be folded forwardly underneath the base to provide an extremely. compact unit. In a preferred embodiment, the base is constructed of upper and lower channel members detachably secured to form a box-like structure. The entire electrical ignition system is housed within this structure. At one end thereof are a pair of contact terminals adapted for electrical connection with the igniter of the miniature rocket. Abutting this end are two relatively small batteries, preferably D-size photoflash batteries,

further detailing the electrical ignipositioned end-to-end in series. One of the contactterminal protrudes inwardly to make electrical contact with the first battery.

A unique pneumatically controlled closure switch is carried within the base proximate the end opposite the contact terminals. The closure switch has a stationary contact which firmly abuts the exposed pole of the second battery. Within the closure switch is a second contact constructed of an elongate strip of resilient conductor material such as spring-tempered copper. One end of the elongate contact is permanently secured while the opposite end rests in a normally open position with "respect to the stationary contact. An electrical conductor communicates between the fixed end of the elongate contact and the second of the two contact terminals at the first end of the launching pad base. An inflatable sac is positioned behind the resilient contact and contained within an enclosure such that as the sac is inflated with any pneumatic fluid, such as air, pressure is exerted upon the resilient contact urging it into position to effectively close the switch. The means for operatively manipulating the closure switch, which is positioned at a remote operators station, consists of a generally elongate body having a longitudinal bore. An elongate plunger is slideably operable within the aforementioned bore. As the plunger is partially withdrawn from the body bore, air enters this bore through a second reduced diameter bore extending longitudinally within the plunger. Air is expelled from the body bore into a flexible conduit which communicates between the bore and the inflatable sac when the operator puts a finger over the bore of the plunger and pushes inwardly.

A safety key is also provided to prevent accidental ignition while the rocket is being prepped, and alternately to provide a continuity check prior to energizing the ignition system. The safety key, in accordance with a preferred embodiment thereof, has a generally rectangular elongate body constructed of non-conductive material, such as a synthetic polymer. Carried at one end thereof is a filament type lightbulb. Either end of the safety key is insertable through the top of the base into the closure switch. When the lightbulb end of the safety key is inserted into the closure switch, the electrical contacts thereof, respectively make electrical connection with the fixed contact and the secured end of the elongate contact to effectively close the switch. However, resistance of the filament within the lightbulb is sufficient to drop a portion of the potential of the battery such that the remaining potential appearing across the igniter is insufficient to activate it. The relative brightness of the filament indicates continuity of the electrical system and also the energy potential of the batteries. Activation of the switch brings the free end of the elongate contact into position against that contact of the lightbulb which is in electrical connection with the fixed contact of the closure switch to bypass the filament resistance and apply full electrical potential to the igniter, thus permitting sufficient current to flow through the igniter to effect ignition of the rocket engine.

Insertion of the other end of the safety key into closure switch positions an insulator between the fixed contact and the elongate contact to prevent accidental activation of the igniter. With the insulating end of the safety key inserted into the closure switch, the model rocketeer may prep his rocket in relative safety. After the rocket is prepped and just prior to retreating term is remote launch station, the rocketeer removes the safety key and reinserts the lightbulb end thereof for a final continuity check and to place the rocket into condition for launching.

Turning now to the drawings in which the presently throughout the several views, FIG. 1 illustrates a launching pad assembly generally designated by the reference character embodying the invention as it would appear in the ready state to launch the miniature rocket 11. The launching pad assembly 10 includes a base member 12 supported by a first leg 13, a second leg 16 and a third leg 17. The triangular spaced support legs are pivotally attached to the base member 12 for axial adjustment thereof as will be hereinafter described in further detail. A launch rod 18 is carried by and extends upright from the base member 12. The conventional miniature rocket 11 comprises an air frame or body tube 19 having a nose cone 20 at its leading edge and a tail section 21 in which is housed the propellant or the rocket engine. Fins 22 carried near the rearward end of the body tube 19 stabilize the miniature rocket 11 during flight. A launching lug 23, essentially a small elongate tubular member attached to the air frame 19 and in axial alignment therewith, slidably engages the launching rod 18 to support and stabilize the miniature rocket 11 during the initial flight phases of ignition and liftoff. An exhaust deflector having a horizontal panel 27 supported above the base 12 and an aperture therein which passes the launch rod 18 and a second panel 29 extending downwardly from the horizontal panel 27 and constructed of metal or other heat-resistant material, protects the launch pad assembly 10 by deflecting the hot exhaust gases outwardly therefrom.

Ignition wires

30 and 31 communicate between the electrical ignition system of the launch pad assembly and the igniter for the rocket engine. The electrical ignition system will be disclosed in the detailed description of FIGS. 6-9. Also shown is the pneumatic operator control for remotely manipulating the electrical system and the flexible conduit that communicates therebetween.

FIGS. 2-5 specifically illustrate and detail the rocket launching pad. The base 12 consists of a lower elongate channel member 36 and an upper elongate channel member 37 secured at the first end by a screw 38 and a knurled thumb nut 39. The second end of the base is similarly secured by a pair of screws and knurled thumb nuts as will be hereinafter described in detail in connection with the second leg 16 and the third leg 17. The base 12 is adjustable in two planer directions about one substantially horizontal axis as indicated by the dashed line 40 and another substantially horizontal intersecting axis as indicated by the dashed line 41 which will become apparent in the following detailed description of the triangular spaced support legs.

The first leg 13 terminates at the lower end with a foot 42 and at the upper end with a pair of spaced

flanges

43 and 46 which straddle the

respective sides

47 and 48 of the base 12. Pivot pins 51 and 52 extend inwardly from the

flanges

43 and 46 respectively and are pivotally carried within

semicircular recesses

51 and 52 respectively in the upstanding side portions of the lower channel shaped member 36. The first leg 13 is pivotal about the axis as shown by the dashed line 53 which is substantially perpendicular to the axis 40 and horizontal to the axis 41. The upper portions of the

flanges

43 and 46 are slideable yet frictionally retained between the downwardly depending sidewalls of the upper channel member 37 and outboard, downwardly directed

tabs

54 and 55. When the leg 13 is pivoted about its axis 53, as indicated by the arcuate doubleended arrow 58, if effectively alters the distance of the first end of the base member 12 from the ground level thus effectively pivoting the base 12 about the axis 41 to provide angular adjustment in one planar direction.

A downwardly directed extension 59 depends from the upper channel member 37 proximate the second end thereof. Similarly, a downwardly directed extension 60 extends from the lower channel member 36 parallel to the upper extension 59. Corresponding bores 61 and 62 carried respectively within the upper extension 59 and the lower extension 60 provide pivotal mounting means for the leg 16. The leg 16 terminates at its lower end with a foot 63 and at its upper end with a panel section 66 shaped to fit between the

extensions

59 and 60.

A bore 65 extends through the panel 66 in substantial alignment with the bores 61 and 62 as carried respectively within the upper extension 59 and the lower extension 60. A screw 66 extends upwardly through the bores 62, 65 and 61 to form a pivotal axis for the leg 16. The pivotal axis for the leg 16, as indicated by the dashed line 69, is perpendicular to the axis 41 in one direction and disposed at an angle thereto in the opposite direction. Movement of the leg 16 in the direction of the oblique arcuate double-ended arrow 70 effectively rotates the base 12 about the axis 40 for angular adjustment thereof in a second planer direction. A knurled thumb nut 67 threadedly engaging the screw 66 provides means for clamping the panel 60 between the upper extension 59 and the lower extension 60 to optionally retain the leg 16 at any selected pivotal posi tion as indicated by the arrow 70. The third leg 17 is substantially analogous to the second leg 16 terminating at its lower end with a foot 63a and at its upper end with av panel 66a supported between an upper downwardly directed extension 59a and a lower downwardly directed extension 60a. A transverse stop member 71 extends across the front of the lower channel member 36. Extending the width of the channel member 36, the stop member 71 abuts the panels 66 and 66a to limit the forward arcuate motion of the

legs

16 and 17 wherein the

legs

16 and 17 lie in a single plane parallel to the axis 41. The rearward arcuate motion of each leg, however, may be continued until the legs lay aside the base 12. The forward arcuate motion of the leg 13 may be pursued until the leg abuts and is substantially parallel to the under surface of the base 12. With the legs so positioned relative to the base, the launching pad presents a compact configuration which greatly facilitates stowage. For simplicity of manufacture and assembly of the device of the present invention, it is noted that the legs 15 and 17 are identical and therefore interchangeable within their respective mounts.

An upright transverse panel 73 having three triangular shaped parallel spaced panels extending forwardly therefrom is carried proximate the second end of the base 12. An upright elongate box-like structure 79 at the junction of the upright panel 73 and the centermost triangular panel 77 provides support means for the launching rod 18. The upright panel 73 and the associated

triangular panels

76, 77 and 78 provide a support for the exhaust deflector 29 in a spaced relationship from thebase l2 and further facilitate heat dissipation.

FIGS. 6-9 specifically detail the electrical ignition system of the present invention as preferably carried within the launching pad assembly 10. The box-like base member 12 formed from the lower channelshaped member 36 and the upper channel-shaped second end bulkhead 90 permit insertion of the electrical leads from the igniter of the miniature rocket.

The closure switch for the electric ignition system is enclosed within an area defined by a first upright panel 91 and a spaced second upright panel 92 within the base member 12. The first upright panel 91 has an aperture 93 therein to permit protrusion of the electric pole 82 of the battery 81. A stationary contact 96 is affixed to the upright panel 91 over the aperture 93 to make electrical contact with the protruding electrical pole 82. An elongate resilient contact 97 having a fixed end 98 and a movable end 99 is spaced from the fixed stationary contact 92. An electrical conductor lead 100 is electrically secured at one end to the resilient contact 97 and at the other end to the isolated contact terminal 87. An inflatable sac 101 is positioned between the resilient contact 97 and the second upright panel 92. When the sac 101 is inflated with pneumatic fluid such as air, the sac expands to bear against the upright panel '92 thereby displacing the resilient contact 97 and urging the movable end 99 thereof toward the stationary contact 96.

The manipulative control device 32 for the electric closure switch hereintofore just described is best viewed in FIG. 6. The control device 32 comprises a generally elongate body having a first end 103 and a second end 106 and a longitudinal bore 107. A plunger 108 is slideable within the bore 107 and carries angular sealing rings 109 to prevent escape of pneumatic fluid between the bore 107 and the plunger 108. A longitudinal bore 110 substends the length of the plunger 108. The control device herein specifically illustrated as the preferred embodiment, utilizes air as the pneumatic fluid. As the plunger 108 is partially withdrawn from the bore 107, air enters the bore 107 through the second bore 110. When the plunger bore 110 is sealed as, for example, by a finger of the rocketeer, and pushed downwardly into the bore 107, the air therewithin is expelled through the flexible conduit 33 into the sac 101 to displace the resilient contact 97 as hereinbefore described. To facilitate partial withdrawal of the plunger 108 from the bore 107, a compression type coil spring may be placed within the bore 107 to exert force against the plunger 108. The pneumatically controlled closure switch permits the rocketeer to be at a position safely remote from the launch site of the rocket and yet utilize a minimal electrical energy source for activation of the rocket igniter. The compactness of the electrical system and the abbreviated length of the electric leads eliminates the prior art necessity of outsized batteries to overcome the resistance in overlength electric leads. The pneumatic closure switch controller further acts as a safety to prevent accidental premature activation of the igniter due to the deliberateness necessary for manipulation of the controller.

FIG. 7 specifically illustrates a safety key for use in connection with the electrical ignition system of the present invention. The safety key generally designated by the reference character 111 has an insulating body portion 112 having an upper end 113 and a lower end 116. An electric lightbulb 117 is carried within the body 111. The lightbulb 117 has a conventional glassenclosed filament 118 proximate the upper end thereof and exposed electric contacts119 and 120 extending from the filament.

The safety key 111 is insertable into the closure switch through an appropriately shaped aperture 121 in the upper surface of the base member 12. It is especially noted that the aperture 121 will accommodate the upper end 113 or, alternatively, the lower end 116 of the safety key 111.

Insertion of the upper end 113 of the insulator body portion 112 into the closure switch renders the switch inoperable. With the launching pad assembly now in the fail-safe condition, the model rocketeer may attend to all electrical connections and adjustments preparatory to launching the model rocket with relative safety of accidental or pre-ignition. After the preparatory phases of launching are completed, the safety key 111 is withdrawn from the base member 12 and the lower end 116 is inserted through the aperture 121. When so inserted, the electrical contact 119 makes electrical connection with the fixed end 98 of the resilient contact 97 while the second contact 120 makes electrical connection with the stationary contact 96. The relative brightness of the filament of the safety key indicates continuity of the electrical system and the potential of the battery. While effectively closing the switch, the filament has a sufficient resistance to drop a portion of the potential of the electrical system such that the remaining potential appearing across the igniter is insufficient to activate it. Subsequent operation of the control device 32, as hereinbefore described, urges the movable end 99 of the resilient contact 97 toward the stationary contact 96. For purposes of safety the resilient contact 97 is of insufficient length for the free end 99 thereof to reach the stationary contact 96 and at the rest position is spaced from the electric contact 120 of the lightbulb 117. When the closure switch is activated, however, the free end 99 is urged against the contact 120 which commonly is in electrical connection with the secured contact 96 to effect a direct electrical connection between the elongate contact 97 and the stationary contact 96 to energize the igniter and ignite the rocket motor.

The insertion of the insulator end of the safety key into the closure switch and the unique design of the manipulative control device provides the rocketeer with the advantage of a double safety during all phases of preparation for launching the miniature rocket. The manipulative control device further provides the rocketeer with a safety while he completes his final continuity check and until he retreats to his remote operators station where, at a safe distance from the ignition blast of the rocket, he need only manipulatively operate the control device.

As will be observed by those skilled in the art, the launching pad assembly and the integral electric ignition system of the present invention avoids many of the practical difficulties which attend the previous prior art methods and devices. In particular, the invention provides a streamlined compact unit free from bulky battery packs and lengthy electrical firing leads, for ease of operation and compact convenient storage and transportation. Similarly, the device described herein provides for a double safety and a continuous continuity check without resorting to sophisticated expensive equipment.

Various changes in the precise form of the invention chosen for purposes of illustration in the drawings, will readily occur to those skilled in the art. For example, the base is described as a rather elongate configuration with the batteries placed end-to-end which could be modified into a substantially rectangular configuration by placing the batteries side-byside. The location of the pneumatically controlled closure switch and the contact terminals might also be varied. These and many other features which do not constitute the essence of the invention, could be modified or substituted with art recognized equivalence. To the extent that such changes and modifications do not depart from the spirit of the invention, they are intended to be included within the scope thereof which is to be determined only by a fair interpretation of the following claims.

Having fully described and disclosed the present invention in what I consider to be the presently preferred embodiment thereof so as to enable those skilled in the art to understand and practice the same,

I claim:

1. In a miniature rocket launching pad including a base presenting a chamber defined by upper and lower channel members and inner and outer end panels; and an igniter; an electrical ignition system comprising:

a. a battery in said chamber having a pole at one end in conductive engagement with a contact terminal connected to said igniter and located on the exterior of said inner end panel and another pole at the other end in conductive engagement with a fixed terminal on the exterior of said outer end panel;

b. a second contact terminal on the exterior of said inner end panel and connected to said igniter;

c. a elongate resilient contact having one end anchored to said lower channel member with its other end normally spaced from said fixed terminal;

(1. a conductor extending between said elongate resilient contact and said second contact terminal;

e. an inflatable sac depending from said upper channel member and in operative engagement with said elongate resilient contact, whereby inflation of said sac moves the end of said elongate resilient contact into engagement with the fixed terminal, and

f. a manipulative control device for introducing air under pressure into said sac.

2. The electrical ignition system of claim 1, wherein said manipulative control device comprises:

a. an enclosure having an aperture therein and constructed to entrap a quantity of pneumatic fluid and controllably expel said pneumatic fluid through said aperture; and

b. a resilient conduit communicating between the aperture of said enclosure and said sac.

3. The electrical ignition system of claim 1, wherein said manipulative control device comprises, in combination:

a. a generally elongate body having a first end and a second end, and a longitudinal bore subtending said first and second ends;

b. an elongate plunger slidable within the bore of said body and sealingly engageable therewith, and extending longitudinally from the first end of said body; and

c. a substantially flexible conduit communicating between the second end of said body and said sac.

4. The electrical ignition system of claim 3, including check valve means for the entrance of pneumatic fluid into the bore of said body between said plunger and the second end of said body.

5. The electrical ignition system of claim 4, wherein said check valve means includes a longitudinal bore substending the length of said plunger.

6. The electrical ignition system of claim 1, in combination with a safety key adapted to controllably prevent accidental activation of said igniter and further adapted to indicate continuity of said electrical ignition system, said safety key comprising an electrical power indicator insertable into an aperture in said upper channel member between said fixed terminal and resilient contact and communicating therewith, said indicator effectively bridging said fixed terminal and resilient contact to indicate the adequacy of the potential accross said contacts, said indicator having a resistance to drop a sufficient portion of the potential such that the remaining potential appearing is insufficient to activate the igniter.

7. The electrical ignition system of claim 1, in combination with a safety key adapted to controllably prevent accidental activation of said igniter and alternately adapted to indicate continuity of said ignition system, said safety key including:

a. a non-electrical conductor body portion having an upper end and a lower end; and

b. an electrical filament carried by said body portion and having a first terminal and a second terminal extending therefrom proximate the lower end, said lower end insertable into said upper channel member between said fixed terminal and resilient contact such that the first terminal of said filament communicates with said fixed contact and said second contact terminal communicates with the anchored end of said elongate resilient contact to effectively close said switch, said filament responsive to the adequacy of the potential across said contacts and having a resistance to drop a sufficient portion of the potential such that the remaining potential appearing is insufficient to activate the igniter.

8. The electrical ignition system of claim 7 wherein operative manipulation of said sac urges the movable end of said elongate resilient contact against said fixed terminal to bypass said filament and apply full potential to said igniter.

Claims

1. In a miniature rocket launching pad including a base presenting a chamber defined by upper and lower channel members and inner and outer end panels; and an igniter; an electrical ignition system comprising: a. a battery in said chamber having a pole at one end in conductive engagement with a contact terminal connected to said igniter and located on the exterior of said inner end panel and another pole at the other end in conductive engagement with a fixed terminal on the exterior of said outer end panel; b. a second contact terminal on the exterior of said inner end panel and connected to said igniter; c. a elongate resilient contact having one end anchored to said lower channel member with its other end normally spaced from said fixed terminal; d. a conductor extending between said elongate resilient contact and said second contact terminal; e. an inflatable sac depending from said upper channel member and in operative engagement with said elongate resilient contact, whereby inflation of said sac moves the end of said elongate resilient contact into engagement with the fixed terminal, and f. a manipulative control device for introducing air under pressure into said sac.

2. The electrical ignition system of claim 1, wherein said manipulative control device comprises: a. an enclosure having an aperture therein and constructed to entrap a quantity of pneumatic fluid and controllably expeL said pneumatic fluid through said aperture; and b. a resilient conduit communicating between the aperture of said enclosure and said sac.

3. The electrical ignition system of claim 1, wherein said manipulative control device comprises, in combination: a. a generally elongate body having a first end and a second end, and a longitudinal bore subtending said first and second ends; b. an elongate plunger slidable within the bore of said body and sealingly engageable therewith, and extending longitudinally from the first end of said body; and c. a substantially flexible conduit communicating between the second end of said body and said sac.

7. The electrical ignition system of claim 1, in combination with a safety key adapted to controllably prevent accidental activation of said igniter and alternately adapted to indicate continuity of said ignition system, said safety key including: a. a non-electrical conductor body portion having an upper end and a lower end; and b. an electrical filament carried by said body portion and having a first terminal and a second terminal extending therefrom proximate the lower end, said lower end insertable into said upper channel member between said fixed terminal and resilient contact such that the first terminal of said filament communicates with said fixed contact and said second contact terminal communicates with the anchored end of said elongate resilient contact to effectively close said switch, said filament responsive to the adequacy of the potential across said contacts and having a resistance to drop a sufficient portion of the potential such that the remaining potential appearing is insufficient to activate the igniter.