Little Joe-II Pages |
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 Magazines, 1/100 A-002, & Quest Micro |  Pages from Part 1, with 1/100 A-002 model | 
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The following article was written by Tom Beach for American Spacemodeling Magazine (The NAR's Magazine, now named Sport Rocketry, which Tom is editor of). Tom's article accompanied the drawings that we did, and several photographs were also included. Some additional photos are included here than what were in the original article. For more photos, see Photos Page 1 and Page 2. For all of the drawings printed with the article, plus bonus drawings, go to the Drawings page.
Little Joe II The Little Joe II was a solid-fueled launch vehicle used to man-rate the Apollo Launch Escape System (LES). The LES was a set of solid motors mounted on a tower atop the Apollo Command Module. In the event of a catastrophic failure of a Saturn V or Saturn 1B launch vehicle on the pad or early in the boost phase the LES motors would ignite and pull the Apollo capsule, with its three astronauts, to safety. The Little Joe II provided a relatively inexpensive way to test the LES over the range of velocity and dynamic pressure conditions expected in a Saturn flight profile. A similar program to man-rate the Project Mercury Launch Escape System used a booster called the Little Joe, so the name Little Joe II was chosen for the Apollo test booster. The Little Joe II was designed and built for NASA by the Convair Division of General Dynamics. Five Little Joe II vehicles were flown; the first was a qualification test of the launch vehicle itself, and the last four were flight tests of the Apollo LES. The launches were conducted at the White Sands Missile Range between August 1963 and January 1966. Table 1 summarizes The LES qualification project also included two Pad Abort tests to simulate an abort while still on the launch pad. Although these tests do not involve the Little Joe II booster, photos of the pad abort vehicles (simply a Command Module and LES) provide data relevant to the Apollo payloads flown on the Little Joe II vehicles. The first pad abort mission (PA-1) was flown on November 7, 1963 using Apollo "boilerplate" capsule BP-6. The second (PA-2) was conducted on June 29, 1965 using the BP-23 that had previously been flown on the Little Joe II mission A-002. Both tests were successful, the LES carrying the CM to sufficient altitude for deployment of the main parachutes. Little Joe II Vehicle Description The drawing at right shows a typical Apollo/Little Joe II configuration. Although each of the five Little Joe II vehicles was unique in detail configuration and payload dimensions, they are similar in overall structure and paint patterns. This article will describe the differences between vehicles so that the modeler may construct any round. Vehicle station (STA) positions are measured in inches from the STA 0.0 reference point at the top of the upper forebody splice ring. Distances rearward are given as positive STA values; distances foreward (into the payload area) are negative STA values. |  |
| Propulsion The versatile Little Joe II could be flown with a variety of solid propellant motor configurations, depending on mission requirements. The body could hold up to seven large Algol 1D motors, or a combination of fewer Algols could be used with smaller Recruit TE-29 motors. All of the Recruits and some (or all) of the Algols were ignited at launch as the "booster" stage; the ignition of some Algols could be delayed until later in the flight to provide "upper stage" or "sustainer" thrust. The motor combinations used gave the Little Joe II a rapid liftoff, not at all like the slow liftoffs associated with Apollo Saturn launches. The Algol 1D motor was produced by Aerojet General. It had an average thrust of 96,530 pounds, a burn time of 42.1 seconds, and a total impulse of 4,068,000 lbf-sec (making it an "X430000-engine" in model rocket parlance). Mod II Algols had straight nozzles, and were used in the center motor mount only. Mod I Algols were equipped with nozzles that could be canted to a preset angle of up to 14°, and were used in the outer motor mounts. The Recruit motor was produced by Thiokol, had an average thrust of 37,100 pounds, a burn time of only 1.536 seconds, and a total impulse of 57,000 lbf-sec (making it a mid-range "R165000-engine"). Recruits mounted in the center position had straight nozzles. Recruits in the outer positions had canted nozzles (some sources list the cant angle as 6.5°; others say 9°).
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Structure All Little Joe IIs had the same body construction. Both the forebody (STA 0.0 to STA 227) and the aftbody (STA 227 to STA 350) were built from corrugated aluminum skin panels stabilized by internal structural rings. The corrugated aluminum skin eliminated the need for longitudinal support stringers, resulting in a lightweight, inexpensive structure. Each body subassembly was made up of 12 panels, each panel 10 corrugations wide (plus overlap), riveted together to give a total of 120 corrugations around the body. These panels were formed by Alcoa Aluminum Company on the same equipment used to make corrugated aluminum siding and roofing, so modelers who use plastic model railroad siding to simulate the corrugations on their models are doing essentially the same thing General Dynamics did. There were three primary thrust support structures within the vehicle. The main thrust bulkhead (bottom at STA 347) formed the rear of the aftbody and had seven 36" diameter motor mount openings for the Algol motors (or, with adapter fittings, Recruit motors). Six external "T"-cross section thrust longerons (two long, four short) transfered thrust loads from the base bulkhead to the aftbody skin. The lower fin mounting lugs were also part of the main thrust bulkhead. The upper fin mounting lugs were the only externally visible parts of another aftbody support bulkhead that was located at STA 278.8. A splice ring was located at the top of the aftbody. The forebody support bulhead was located at STA 34.75 and held the tops of the Algol motors in place. The six tie-down lugs and two launcher mast fitting hooks on the exterior of the forebody were anchored to this bulkhead. Most of the Little Joe II's electrical equipment was attached to this bulkhead or located in the open space above it. Access to this equipment compartment area was provided by three doors in the outer skin. Splice rings were located at the top and bottom of the forebody. Air conditioning for the Little Joe II while on the launch pad was provided by hose connections to two small doors located on the aftbody, and to one of the equipment compartment access doors in the forebody . Photos of the Little Joe II on the launcher often show air conditioning hoses connected to these doors, or show the doors with the hose adapters in place (e.g., NASA photo 65-HC-991). The Little Joe II had two wiring tunnels, one running the length of the whole body, and one running just the length of the aftbody. The wires were simply laid into negative corrugations (corrugation depressions or "gutters") and sheets of aluminum were attached over the top. Fairings allowed the wires to pass around outside the splice rings at STA 227 and around the base thrust bulkhead. The bottom fairings had umbilical connectors which provided contact to the ground support cables. The only substantial body detail differences between the five Little Joe II vehicles were the positions of externally mounted antennas. Table 2 specifies the antenna types and positions for each vehicle. Both the forebody and aftbody had noticeable rivet lines; longitudinal lines located along the body panel splices, and circumferential lines where internal support rings and bulkheads were located. Modelers interested in rivet level details on the body skin are advised to get an enlargement of NASA photo 64-H-2456, or to visit and photograph one of the two remaining Little Joe II vehicles. |
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|  12-51-1 body, for A-002 (short fin root fairings) NASA Photo # 64-H-2456
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Two versions of the Little Joe II were produced. The 12-50 series vehicles were unguided, utilizing fixed fins for stability (not unlike gigantic, metallic, model rockets). The 12-51 series vehicles had active guidance control: An Aerodynamic Control System utilizing fins with movable elevons; and, in some cases, a Reaction Control System using hydrogen peroxide fueled thrusters. Fairings mounted around the roots of the fins on 12-51 series vehicles housed the RCS and part of the ACS equipment. The rest of the ACS hydraulic system was mounted internally and externally on the fins. The first 12-51 vehicle (12-51-1) for flight A-002 used a short fin-root fairing; later 12-51 vehicles had larger fin-root fairings to accomodate a dual-supply hydraulic system. The Aerodynamic Control System allowed 12-51 series vehicles to perform pitch-up maneuvers prior to abort to increase dynamic pressure on the test vehicle. The Reaction Control System utilized eight 600 pound thrust motors, and was designed for use at liftoff (while airspeed was low) and at high altitudes where the ACS would be ineffective. |
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Payloads Most of the payloads carried by Little Joe II vehicles were "Boilerplate" Apollo capsules. A boilerplate is a test article with the same size, mass, and center of gravity as a production spacecraft. The boilerplates do not include all the active systems of a production spacecraft, but they usually include equipment to measure and record engineering data during the test. The first mission (QTV) carried a dummy Apollo supplied by General Dynamics. The final mission (A-004) carried SC-002, a "Block I" production model Apollo spacecraft. On all missions (except A-001 & QTV) the Command Module was covered by a Boost Protective Cover (BPC). The BPC protects the CM during boost and would be jettisoned along with the escape tower during a normal Apollo launch. The BPC has two parts; a rigid forward section, and a rear "soft" cover. Many photos of Little Joe II vehicles on the launcher show the soft BPC either partially or completely missing (not yet mounted). The Launch Escape System is made up of three separate solid-fueled motors. The main launch escape motor that actually pulls the CM away from the booster has four canted nozzles, a thrust of 147,000 pounds, and a burn time of 3 seconds (a "U-engine"). A pitch control motor, mounted near the LES nose and pointed horizontally, also ignites at abort to deflect the capsule away from possible booster debris. The pitch motor has a thrust of 2,850 pounds and a burn time of 0.5 seconds (a wimpy "M-engine"). Between the main escape motor and the pitch motor is mounted the tower jettison motor, with two nozzles canted out through the sides of the LES (where they appear as elliptical openings). This motor fires to pull the LES away from the CM, either after an abort or after successful second stage ignition during a normal flight. The separation motor has a thrust of 32,000 pounds and burns for 1 second (a "Q-engine"). On all missions (except A-001 & QTV) the Launch Escape System was equipped with nose canards. These canards, part of the escape tower nose structure, were folded flush during boost. Eight seconds after escape motor burnout the canards swung out to flip the Launch Escape Vehicle (CM + LES) around and stabilize it in a heat shield-forward attitude, allowing more reliable CM parachute deployment. |
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The Little Joe II body, fins, and fairings were left in their natural aluminum finish. The base ring skin and splice rings were also natural metal color, but were darker than the body. The upper splice ring at STA 227 usually appears darker than the lower ring in photographs, but this is probably an effect of overhead lighting on the slighlty slanted surface. The "UNITED STATES" lettering at +Y and -Y was black. The General Dynamics plaques on the base ring had black lettering on a polished aluminum background. The base of 12-51 series vehicles (including fairing bottoms and fin trailing edges) were covered with RTV silicone rubber as thermal protection, and had an off-white color. The 12-50 series vehicles had bare metal bottoms. The Algol nozzles were painted white, but Mod I (canted) nozzles appear to have had a black, flexible covering around the throat area of the nozzle (possibly as protection for the nozzle cant angle adjustment mechanism). The color of the Recruit motor nozzles is unknown, but they appear dark in photos. The dummy Apollo payload carried on the QTV mission was silver in color, with a shifted variation of the standard black roll pattern on the dummy SM. All other Apollo payloads were painted white with standard black roll patterns. Large "black dots" that appear at the rear of the boilerplate Service Modules, and on the mating ring below the SC-002 SM, were actually vent holes for pressure equalization. Note that, except for the A-001 mission, the Command Module was covered by a Boost Protective Cover. The Command Module had the same black-on-white roll pattern that was on the BPC, but the CM also had a 6" tall reddish-orange stripe around the base (the A-001 BP-12 CM did not have this stripe). The Command Modules (not the BPCs) also had "UNITED STATES" and American flag markings in two places. The Launch Escape motors (except for the dummy on QTV, which was white) were painted with black-on-white roll patterns. A-001 had a unique LES roll pattern, but subsequent missions had a standard LES roll pattern. LES nozzles were black. The launcher used to fly the Little Joe II vehicles was painted a slightly orange shade of yellow. |
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Table 1 lists the launch date, vehicle number, motor configuration, and payload for each mission. Additional notes on each flight are given below. | |||
 | QTV: This first flight of the Little Joe II was a Qualification Test Vehicle to prove the design of the launch vehicle. The dummy CM+SM+LES it carried had no abort capability but the vehicle was aimed to pass through the "transonic abort" test window as a rehearsal for the next flight. After successfully passing through the test window a radio command was sent to fire explosive charges that would rupture the Algol motor casing to terminate it's thrust and destroy the vehicle -- but the command had no effect, and the vehicle impacted intact downrange. |  S-63-15699.jpg |  S-63-15701.jpg |
 | A-001: The first test with an active LES, it repeated the trajectory of the QTV mission. The thrust termination blast was successful, destroying the Little Joe II, and the abort was acceptable, although the capsule did re-contact booster debris during the abort. Excessive oscillation of the capsule caused one of the three main parachutes to rip away at deployment, but the capsule landed successfully on the remaining two 'chutes. Later missions employed canards on the LES to stabilize the CM in a heat-shield-forward attitude and prevent excessive oscillations. |  S-64-17762.jpg |  S-64-17494.jpg |
 | A-002: The objective of this mission was to boost the boilerplate Apollo to a velocity, altitude, and pitch angle that would produce a greater dynamic pressure on the escape vehicle than would be expected during a "hot" Saturn V boost. The abort actually occured outside the targeted test window, but at an even greater dynamic pressure than expected, so the test was a success, with the CM landing safely under three 'chutes. Dynamic pressure is represented by the symbol "Q", so this was labeled a "Max-Q abort". This Little Joe II was equipped with the Aerodynamic Control System to provide pitch-up before abort. It also had an active Reaction Control System, but only to test the system for to the next mission. |  64-H-2456.jpg |  64-H-2805.jpg |
 | A-003: The objective of this mission was a high-altitude (about 20 miles) abort, but a control system failure prevented this. At launch, fin 4 locked over to maximum deflection. The other fins and the RCS system tried to compensate, but were unsuccessful, and the roll rate of the vehicle increased until centrifugal forces resulted in disintegration of the Little Joe II at 12,400 feet. The LES sensed the failure and initiated an emergency abort, successfully pulling the BP-22 capsule away for a safe recovery, a consolation prize for the Apollo engineers. Upon impact in the desert, the unignited upper stage Algol motors were observed to ignite violently, throwing burning and unburned propellant within a radius of several hundred feet. Nice prang. |  S-65-19755.jpg | .jpg) 65-H-823.jpg |
 | A-004: The last mission carried an early production model Block I Apollo spacecraft (CM and SM). The LES was modified (by removing nose ballast and tilting the escape motor nozzles to produce a net thrust vector 3.4° off vertical) and the Little Joe II was pitched-up prior to abort to insure that the Launch Escape Vehicle (CM+LES) would tumble during the firing of the abort motors. This resulted in the soft BPC ripping off and escape motor thrust impinging onto the CM, but the abort was successful and the capsule was recovered in fine shape. This was the only Little Joe II mission with a successful ignition of "upper-stage" Algols, the two sustainer Algols igniting 36.4 seconds into the 42.1 second burn of the two booster Algols. The 12-51-3 Little Joe II used ACS control only; the holes for the RCS motors in the fin-root fairings were covered with octagonal plates riveted in place. |  65-HC-991.jpg |  S-66-18201.jpg |
| Remaining Little Joe II Hardware A total of eight Little Joe II vehicles were built by General Dynamics. Airframes 12-50-3, 12-50-4, and 12-51-4 were not flown and two of them still exist on display. One of the 12-50 series vehicles is on display at the Lyndon B. Johnson Spaceflight Center near Houston, Texas. The vehicle is sitting on the Little Joe II launcher used in White Sands, and is mated with the Boilerplate capsule BP-22 (flown on A-003), a Launch Escape Tower, and a Block II Service Module. Strangely, the vehicle is not equipped with the fixed fins that would be expected on a 12-50 series model, but instead sports the movable-elevon fins and the lower part of the fin-root fairings that belong on vehicle 12-51-4. A bit confusing, but still an excellent opportunity for photographing details of the body, fins, and fairings (as long as you understand the situation). The short wiring tunnel cover plate is not on the aftbody. The roll patterns on the LES and SM are incorrect, and the CM lacks a Boost Protective Cover. Because the vehicle is sitting atop the launcher, modelers cannot reach it to make measurements. Little Joe II number 12-51-4 is on display at the International Space Hall of Fame Museum in Alamogordo, New Mexico, topped by a Block II SM, dummy capsule, and dummy escape motor. A set of fixed fins and just the tops of fin-root fairings (the bottoms of which are on the Houston Joe) are mounted on the vehicle. The display provides excellent photo opportunity for those interested in body details and fixed fins, and the vehicle is mounted low enough to allow measurements of the bottom sections. The Boilerplate BP-23 Command Module (flown on A-002 and Pad Abort-2) is on display at Marshal Space Flight Center at Huntsville, Alabama. It lacks a BPC and has an incorrect paint pattern, but the LES tower framework and the lower part of the LES motor provide useful scale data. |
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| Acknowledgements The authors would like to thank Wayne Hendricks, George's teammate, whose interest in modeling the Little Joe II set in motion the creation of this data presentation. We would also like to thank Joyce Guzik, Tom's teammate, for her assistance on trips to gather measurements of the Little Joe II in Alamogordo. Finally, we wish to express our appreciation to the following people for helping us locate data about the Little Joe II (the list is long, but Tom has been collecting Little Joe II info since 1978): Mr. J. B. Hurt, Little Joe II Project Program Manager, General Dynamics, Convair Division, San Diego, California Mr. W. W. Petynia, Program Manager, National Aeronautics and Space Administration (NASA), Johnson Spaceflight Center, Houston, Texas Mr. Robert Turner, Assistant Curator, International Space Hall of Fame Museum, Alamogordo, New Mexico Mr. Tom Winston, Photo Library Archivist, NASA Photo Library, Johnson Spaceflight Center, Houston, Texas Ms. Lois Morris, Assistance Archivist, The Fondren Library, Rice University, Houston, Texas Ms. Nancy Dumas and Mr. Jim Eckels, Public Affairs Office, Army White Sands Missile Range and the late Herb Desind, for access to his enormous collection of NASA photos. |
| Photo Descriptions:
NASA Photo 65-HC-991 (color) Mission A-004 vehicle on launch pad. Fin-root fairing tops are not yet in place. Removed before flight: Plastic and tape that covers the elevon actuators, fin tips, and parts of the escape motor; yellow covers on LES nozzles; small red and yellow dots on the BPC; and air conditioning adapters that are visible on upper and lower access doors | | ||
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NASA Photo S-65-19888 (B&W) Other side of A-004 vehicle on launcher. The structure in the background is a rail-mounted gantry that is rolled in to assemble and service service Little Joe II vehicles on the launcher. |  | ||
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NASA Photo 66-H-24 (B&W) Mission A-004 launch. Two Algols and five Recruit motors are firing at this point. This is actually only half of NASA photo 66-H-24; the other half (not shown here) shows recovery crew inspecting the CM after landing. | .jpg) | ||
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NASA Photo S-65-19752 (B&W) Mission A-003 vehicle on launcher. Fin-root fairings are not attached yet so the RCS and ACS plumbing is visible. The soft Boost Protective Cover is not yet in place, revealing the CM paint pattern. The tape on the SM and LES, and the black ball covering the LES nose tip were removed prior to launch. |  | ||
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NASA Photo 65-H-823 (B&W) Disintegration and emergency abort of mission A-003. In picture 1 you can see the full deflection of fin #4 and the top of an Algol motor poking through the side of the vehicle. Picture 3 shows the successful abort; note the pitch motor plume. Photo 65-H-823 is a sequence of four photos covering the abort. |  | ||
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NASA Photo 64-H-2456 (B&W) Little Joe II vehicle 12-51-1 (mission A-002) checkout. The fin actuator fairings and some of the fin-root fairings are not yet in place. The antenna plates at STA 131.05 are not mounted yet (one of them will partially cover the "D" in UNITED STATES). Note guy wires attached to the tie-down lugs to stabilize the vehicle. | | ||
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NASA Photo 64-H-2805 (B&W) Mission A-002 launch. Two Algols and four Recruits are firing. Note the short fin-root fairings that were used on this vehicle only. | | ||
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NASA Photo S-64-31084 (B&W) Little Joe II 12-51-1 (mission A-002) . Body during horizontal checkout. Note the RTV base coating, the fin attach lugs, and the openings where Algols and Recruits will be mounted (ballast weight was mounted in the center position on this flight). |  | ||
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NASA Photo S-64-17494 (color) Mission A-001 launch. One Algol and six Recruits are firing. Note the shininess of the Little Joe II's aluminum skin compared to the flat black and white of the Apollo payload. | | ||
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NASA Photo S-63-15699 (color) QTV Little Joe II 12-50-1 on launch pad. Note the antenna arrangement, the dummy LES tower structure, the capsule vanes (nearly edge-on), the sharp CM-SM joint, and the orientation of the SM roll pattern; all are features unique to this vehicle. | | ||
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NASA photo 63-LJII-8 (B&W) QTV on launch pad. Note the capsule vane and the antenna on the side of the SM. |  | ||