Author Topic: Thor Booster Variants  (Read 18947 times)

Offline edkyle99

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Thor Booster Variants
« on: 07/18/2016 03:45 AM »
This is going to take awhile, given the numerous Thor and Delta variants.

In 1955 the U.S. began Thor IRBM development as a stop-gap until Atlas could enter service.  Thor would use Atlas-derived propulson and warhead and an existing inertial guidance system.  It would have 2,400 km range to reach the Soviet Union from Western Europe.   Douglas Aircraft Company won the SM-75 Thor contract in December 1955.  The company delivered its first Thor from Santa Monica, California to Cape Canaveral on October 26, 1956. 

The early R&D Thors, named Douglas Missile 18, or DM-18, were powered by 135,000 lbf Rockeydyne MB-1 engines and topped by dummy nose cones. Thor 101 blew up on its LC 17B launch pad on January 25, 1957.  This was followed by three more failures.  Finally, on September 29, 1957, still less than two years after the program began, Thor 105 flew a successful long-range flight from the Cape.  One month later, Thor 109 flew the first full-range flight down the Atlantic Missile Range.   

All-inertial guidance system test flights began in December, 1957.  Reentry vehicle test flights began in February 1958 with Thor 120, which also debuted a new, less-tapered guidance section. 

Thor DM-18A, the operational variant without fins, numbered Thor 138 and higher, began flying in 1958.  The first crew training launch from Vandenberg, which was also the first long-range launch from that West Coast base, took place on December 16, 1958, when Thor 151 flew successfully over the Pacific Ocean.

Thor became operational in Great Britain during December 1959.   There, 60 Thors were deployed at four former airfield bases.  A total of 1,000 personnel manned each base.  Thors were stored horizontally in retractable steel shelters on an erector-launcher mount.   Missiles could be launched within 15 minutes of an order, in theory.   

Thors were retired from IRBM duty in August 1963 and returned to the United States where nearly all would be assigned to other duties.

 - Ed Kyle
« Last Edit: 07/18/2016 03:52 AM by edkyle99 »

Online kevin-rf

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Re: Thor Booster Variants
« Reply #1 on: 07/18/2016 05:11 AM »
Ed. I am looking forward to learning new things. Given the volume that needs to be covered, this will be a long thread!
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Offline kevind

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Re: Thor Booster Variants
« Reply #2 on: 07/18/2016 06:08 PM »
10 months from signing contract to delivery of first vehicle.  Probably could never be done that quickly today.

Offline gwiz

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Re: Thor Booster Variants
« Reply #3 on: 07/18/2016 06:46 PM »
It's debugging the software that takes the most time with today's vehicles.

Offline Old Space Dude

Re: Thor Booster Variants
« Reply #4 on: 07/24/2016 12:46 AM »
 During the first quarter of 1960, there were three Thor launchings from the cape which were said to be testing an
improved engine. Each flew what was called at the time an experimental low-drag fairing covering the Mk 2
re-entry vehicle. These looked very much like a Jupiter re-entry vehicle. Can anyone enlighten me on this?

Offline edkyle99

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Re: Thor Booster Variants
« Reply #5 on: 07/24/2016 03:50 AM »
During the first quarter of 1960, there were three Thor launchings from the cape which were said to be testing an
improved engine. Each flew what was called at the time an experimental low-drag fairing covering the Mk 2
re-entry vehicle. These looked very much like a Jupiter re-entry vehicle. Can anyone enlighten me on this?
DM-18C.  Had MB-3 Block 2 165 Klbf engine.  This was a test vehicle meant to demonstrate longer range.  It had a low drag fairing and a GE Mark 2 RV.  The fairing would not have shared anything with the Jupiter RV, because the Jupiter RV was a conical ablative reentry vehicle.  The Thor fairing was just a jettison-able fairing to reduce drag, while the stumpy heat-sink Mark 2 RV used by the operational Thors still lurked beneath.  All three launches were from LC 18B, which had a tactical launcher setup.  I'll add details later.

 - Ed Kyle
« Last Edit: 07/24/2016 02:12 PM by edkyle99 »

Offline edkyle99

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Re: Thor Booster Variants
« Reply #6 on: 07/24/2016 09:54 PM »
"Thor-Able" (orginally proposed as "Thor-Vanguard") was a Thor first stage topped by Vanguard second, and in some cases, third stages.  The second ("Able") stage was a pressure-fed nitric acid/UDMH stage powered by an Aerojet AJ-10 series engine. The third stage was a spin-stabilized Allegany Ballistics Lab X-248 "Altair" series solid motor.

The rocket, in two-stage form, was created by Ramo-Wooldridge Space Technology Laboratories (as the prime contractor) to test ICBM ablative reentry vehicle techology before Atlas and Titan were ready.  In 1958 it flung GE Advanced Reentry Test Vehicles more than 10,000 km to prove the ablative technology.  It was the first time that a big USAF liquid fueled rocket had staged successfully.  The two-stage rocket was controlled by an autopilot rather than an active guidance system.

Someone at STL quickly realized that Thor-Able could be turned into an ICBM (briefly named "Thoric") - that it would be able to carry the lighter RVs and warheads soon to appear.  The idea was rapidly quashed by the chain of command, which also removed STL from the Thor-Able prime contractor role in favor of Douglas.

Thor's first orbital attempts were part of ARPA's "Operation Mona", better known as "Pioneer" - the name assigned by NASA when it assumed control after the first launch.  Pioneer was the first U.S. attempt to reach the Moon.  Adding radio guidance to the Able second stage and an ABL X-248 third stage created the "Thor-Able 1" variant to do the attempt.  Three attempts in 1958 failed to reach the moon, but did manage to loft Pioneer 1 to record altitude where it collected data on the Van Allen belts.

"Thor-Able 2" was a two-stage variant with BTL guidance in the Able stage that boosted GE "RVX-1" (or "Precisely Guided Reentry Test Vehicle") scaled ablative reentry vehicles on multiple ICBM-distance flights  in 1959.  RVX-1 looked a lot like the Mark 3 and 4 RVs that later topped Atlas and Titan ICBMs.  The Navy managed to recover some of these, proving the design.

Thor-Able 2 with a third stage orbited NASA TIROS 1, the first weather satellite, in 1960.  Thor-Able's 3 and 4 orbited NASA's Explorer 6 and Pioneer 5 in 1959 and 1960, respectfully.  These used an improved AJ10-101A second stage engine.

Thor-Able served as the starting point for NASA's highly successful Thor-Delta, which first flew in 1960.

 - Ed Kyle
« Last Edit: 07/24/2016 10:01 PM by edkyle99 »

Offline Antilope7724

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Re: Thor Booster Variants
« Reply #7 on: 07/25/2016 12:42 AM »
From the Defense Technical Information Center website, this pdf:

"A Satellite and Space Vehicle Program for the Next Steps Beyond the Present Vanguard Program. - Dec 10, 1957 - Naval Research Laboratory. - 130 pages

Diagrams in PDF:

pg 110 - Fig. 30 - Thor-Vanguard vehicle
pg 114 - Fig. 34 - Improved Thor-Vanguard three-stage vehicle.
pg 117 - Fig. 37 - Improve Thor-Vanguard four-stage vehicle


http://www.dtic.mil/dtic/tr/fulltext/u2/339967.pdf

Offline Antilope7724

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Re: Thor Booster Variants
« Reply #8 on: 07/25/2016 01:11 AM »
From the Defense Technical Information Center website, this pdf:

"Preliminary Plan for Operation Fish Bowl (Atomic Test using Thor missile). - Nov 1961 - Air Force Special Weapons Center, Kirtland Air Force Base, New Mexico"


Diagram in PDF:

pg A10 - Fig. 4 - (Thor) Typical Launch Emplacement and Control Area


http://www.dtic.mil/dtic/tr/fulltext/u2/a469481.pdf

Offline Antilope7724

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Re: Thor Booster Variants
« Reply #9 on: 07/25/2016 01:36 AM »
From Archive.org:

"Design feasibility report: Thor test booster for the NASA manned space capsule"
Douglas Aircraft Company - Dec 1958

Diagrams in PDF:

Pg 13 - Figure 1 - Thor Test Booster for NASA Capsule - Outboard Profile

Pg 14 - Figure 2- Thor Test Booster for NASA Capsule - Detail of Adapter Section

https://archive.org/details/nasa_techdoc_19780072545

Offline edkyle99

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Re: Thor Booster Variants
« Reply #10 on: 07/31/2016 12:34 AM »
At the dawn of the Space Age the highest priority U.S. space program was U.S. Air Force Weapons System 117L, also known as the Advanced Reconnaissance System. One component of WS-117L was the "Corona" photographic "spy" satellite, which returned exposed film in small "satellite recovery vehicles".

For the program, Lockheed Missiles and Space Company developed a new upper stage named "Hustler", later renamed "Agena".  Agena A was more than a rocket stage, it was an orbiting platform for Corona - a spacecraft in its own right.  It was powered by a Bell 8048 UDMH/IRFNA turbopump-fed engine.  The engine was not restartable, so after separating from Thor the stage would coast for a couple of minutes to apogee before beginning its burn.  Agena's forward section housed an inertial guidance system that used horizon sensors to provide updates.  Cold-gas thrusters located in its aft section provided flight control. 

Fifteen Thor-Agena A launches occurred between February 28, 1959 and September 13, 1960.  All launched toward near-polar orbits from converted Thor IRBM pads 75-3-4 and 75-3-5 at Vandenberg AFB.   The missions were given the "Discoverer" cover name.  Discoverer was said to be a scientific research effort, but it was actually a Corona development program.   

Development was hard-won.  One Agena A stage was destroyed even before the first flight in the "Discoverer Zero" pad accident on January 21, 1959. *   Six of the 15 Thor-Agena A launches failed to reach orbit, and a seventh launch failed to achieve the proper orbit due to a guidance system failure.  Brand-new Agena was most-often the culprit.  Not until Discoverer 13, flown in August 1960, would a capsule be orbited and successfully recovered - the first man-made object recovered from space.  Discoverer 14 returned film containing images taken by the spacecraft's Keyhole camera.  The images covered 1.5 million square miles of Warsaw Pact territory and revealed the presence of 64 previously unknown airfields, 26 surface to air missile sites, and a previously unknown launch center at Plesetsk.

 - Ed Kyle

* A sneak circuit triggered during a pre-launch test caused the stage to fire its ullage rockets. Agena 1019 was subsequently scrapped, but the Thor 160 booster was refurbished and used on the Discoverer 12 flight in 1960.
« Last Edit: 07/31/2016 03:16 PM by edkyle99 »

Offline edkyle99

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Re: Thor Booster Variants
« Reply #11 on: 08/02/2016 04:33 PM »
Thor DM-18C was a special test vehicle that was powered by an upgraded Rocketdyne MB-3 Block 2 (LR-79-NA-11) engine that produced 165,000 pounds thrust.  A GE low drag fairing topped the missile, covering the standard GE Mark 2 reentry vehicle.  DM-18C tested the improved, higher thrust engine and demonstrated modest range improvement.  Three launches, all from Cape Canaveral LC 18B, took place during January-February, 1960 (Thors 256, 259, and 263).  All were successful.

MB-3 Block 2 would soon begin to power Thor space launch variants.

 - Ed Kyle
« Last Edit: 08/02/2016 07:19 PM by edkyle99 »

Offline edkyle99

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Re: Thor Booster Variants
« Reply #12 on: 08/05/2016 12:34 AM »
In 1960, ARPA and the U.S. Air Force began flying Thor-Able-Star, originally named "Thor-Epsilon" which used the Aerojet General "Able-Star" pressure-fed hypergolic second stage powered by an AJ10-104 series engine.  Developed for primary customer the U.S. Navy, Able-Star was the world’s first re-startable stage.  It was a fat version of the Able stage, carrying more than twice as much propellant. 

Thor's tapered guidance section was replaced by a stepped interstage adapter.  MB-3 Block 1 150 Klbf engines apparently powered the initial Thor boosters, with MB-3-2 165 Klbf engines replacing them at some point.  A lightweight STL guidance system topped the second stage.  Nitrogen jets provided three-axis flight control of the stage during coast periods. 

Thor-Able-Star flew 19 times during 1960-65, including 11 launches from the Cape and 8 from Vandenberg AFB.  It performed the first in-space stage restart during its first flight on April 13, 1960.  After the stage completed its initial 258 second burn, it and its Transit 1B payload coasted for 19 minutes before the stage performed a second, 13 second long burn to raise the orbit. 

Early flights orbited the U.S. Navy's initial Transit (navigation) and U.S. Army's Courier (communications) satellites, along with Solrad/GRAB electronic intelligence radar signal "spy" satellites flown piggyback with Transit.  The final two of six Cape-launched Transit satellites were powered by SNAP 3B nuclear power sources (radio-isotope thermoelectric generators or "RTGs") - the first time that RTGs were launched into orbit.  Thor-Able-Star also orbited ANNA 1B (Army, Navy, NASA, Air Force) a satellite that carried beacons for use in ground surveying.   

Thor-Able-Star flew from Vandenberg AFB Complexes 75-1-1 and 75-1-2 during 1963-65.  The sites were later renamed Space Launch Complex (SLC ) 2 East and 2 West, respectively.  All eight Vandenberg launches carried Transit navigation satellites, aimed toward near-polar orbits.  They used SNAP 9A RTGs, which were loaded with more Plutonium 238 than the SNAP 3B RTGs.  The SNAP 9A design was discontinued after the Transit 5-BN-3 flight failed to reach orbit due to an Able-Star stage failure.  The RTG disintegrated in the atmosphere releasing about 1 kg of Plutonium 238.  The final five Transit-O ("Oscar")  missions, all successful from a launch vehicle perspective, used solar powered satellites.

Thor Able-Star's early flight record was spotty, with five launch vehicle failures, two by Thor and three by Able-Star, during the first 10 flights.  But only one of the final nine Thor Able-Stars, the one that carried the last nuclear powered Transit, failed, and the Thor first stage itself flew successfully during the final 14 flights. 

Although August 13, 1965 saw the last flight of Thor-Able-Star, the basic stage structure would subsequently migrate to NASA's ever-improving Delta launch vehicle.  Today's Delta 2 second stage still uses the basic design. 

 - Ed Kyle
« Last Edit: 08/06/2016 02:59 AM by edkyle99 »

Offline edkyle99

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Re: Thor Booster Variants
« Reply #13 on: 08/17/2016 11:49 PM »
NASA’s Milton Rosen coined the rocket name "Delta".  He chose “Delta” because it would be the fourth Thor-based space launch vehicle after Thor Able, Thor Able-Star, and Thor Agena.  Rosen had led the Naval Research Laboratory’s Viking sounding rocket and Vanguard satellite programs.  He transferred to NASA in October 1958 along with 157 NRL Vanguard program employees to form the Agency’s new Goddard Space Flight Center. 

Thor-Delta was an adaptation of Thor-Able 2 (originally "Thor-Vanguard").  It was meant to serve as an "interim" launch vehicle for NASA, until larger Atlas launch vehicles (Atlas Vega and Atlas Centaur were the plan at the time) were brought on line.  A cold gas-jet attitude control system was added to the previous Able second stage to create Delta.  With this system, Delta could coast and reorient itself in space after its pressure-fed AJ-10-118 engine had performed its burn.  This improved the accuracy of solid fuel third stage spin-up insertions.  Both upper stages were tweaked and weight was shaved from Thor itself.  A Bell Telephone Laboratories BTL-300 radio guidance system was added in an equipment compartment atop the second stage to control the vehicle. Typical missions saw the second stage coast for several minutes after its burn before aiming and spin/separating the ABL X-248-A5 third stage.

Goddard ordered 12 Thor-Deltas from Douglas Aircraft and the other stage contractors in April 1959.  The first, carrying Echo 1 from Cape Canaveral’s Complex 17A on May 13, 1960, failed.  A re-try in August with Echo 1A succeeded.  So did the third, and fourth, and so on until all of the final 11 were successful.  They orbited five Tiros, two Explorer, one Orbiting Solar Observatory, Ariel 1 the first U.K./U.S. satellite, Echo 1A, and Telstar 1 the famous experimental AT&T active repeater communications satellite. With such unprecedented success, NASA removed the "interim" label and ordered more, improve Thor-Deltas, about which more later. 

 - Ed Kyle
« Last Edit: 08/18/2016 02:49 AM by edkyle99 »

Offline edkyle99

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Re: Thor Booster Variants
« Reply #14 on: 08/24/2016 06:32 PM »
More-capable Thor Agena B began flying on October 26, 1960.  It launched 43 times, failing eight times, during its five-years of service.  It used an upgraded DM-21 Thor first stage powered by an MB-3 Block 2 (initially) or Block 3 engine that produced 165 to 170 Klbs of liftoff thrust.  The original Thor guidance section was replaced by a shorter, lighter adapter section.  The Agena B second stage, which was powered by the restartable 16 Klbf thrust Bell 8081 (initially) or 8096 engine engine, was 60 inches in diameter and weighed about 14,770 lbs fueled.  It carried two times more propellant than Agena A and used a more powerful, more efficient engine that also gained payload capability by being able to restart.  Like Agena A, Agena B was a spacecraft in its own right, able to maintain attitude while operating on batteries for up to two weeks. 

The improved launch vehicle orbited Keyhole 2 through 5 (mostly) film return spysats and three "Ferret" electronic intelligence satellites.  It also flew several times for NASA, orbiting second generation weathersat Nimbus 1, Canadian ionespheric satellites Alouette 1 and 2, and NASA's Echo 2 and Explorer 31.  Alouette 1, the first non-U.S. or U.S.S.R. built satellite, operated for a then-unheard-of decade.

Thor Agena B flew from three VAFB pads, flying 17 times in 1961 and 18 times in 1962.

Most of the NASA launches took place a year or two after Thor Agena B was done with its Pentagon work.  The NASA launchers appeared to use Agenas that were similar to the three Ferret launchers, with longer cylindrical equipment sections rather than the partially tapered sections used by the KH Agenas.

 - Ed Kyle
« Last Edit: 09/10/2016 02:50 PM by edkyle99 »

Offline Blackstar

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Re: Thor Booster Variants
« Reply #15 on: 08/24/2016 07:53 PM »
I think that the Agena B could restart only once or twice. When they developed the Agena D it had a multi-start capability.

Offline edkyle99

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Re: Thor Booster Variants
« Reply #16 on: 08/25/2016 02:11 AM »
I think that the Agena B could restart only once or twice. When they developed the Agena D it had a multi-start capability.
Yes.  As near as I can tell, most of the Thor Agena B missions, which either went to LEO or to slightly elliptical orbits with low perigees, used a single restart for a total of two Agena burns.  The first burn was usually something like 234-ish seconds duration, while the second burn at first apogee would only last a few seconds.  Agena B was the second stage to restart in orbit (Able Star was first), but it was the first turbopump powered stage to restart.

 - Ed Kyle
« Last Edit: 08/25/2016 02:14 AM by edkyle99 »

Offline Old Space Dude

Re: Thor Booster Variants
« Reply #17 on: 08/28/2016 12:51 AM »
  As I understand things, the Thor-Delta used an improved first-second stage separation system that was tested on the last two Thor-Able launchings.

  The Thor-Ablestar launch failure of April 1964 has always seemed to be something of a mystery as to what
exactly went wrong.

  I have always thought that the Thor-Agena -D launch of the Star-rad payload of October 1962 must have looked like the 1962 Ferret vehicles, with just a simple nose cone atop  the Agena.

  Any comments?

Offline gwiz

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Re: Thor Booster Variants
« Reply #18 on: 08/28/2016 09:45 AM »
That's what the pictures in the Peter Hunter collection show.

Offline edkyle99

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Re: Thor Booster Variants
« Reply #19 on: 08/28/2016 03:09 PM »
  As I understand things, the Thor-Delta used an improved first-second stage separation system that was tested on the last two Thor-Able launchings.

  The Thor-Ablestar launch failure of April 1964 has always seemed to be something of a mystery as to what
exactly went wrong.

  I have always thought that the Thor-Agena -D launch of the Star-rad payload of October 1962 must have looked like the 1962 Ferret vehicles, with just a simple nose cone atop  the Agena.

  Any comments?
The Star-rad shroud had a similar conical section, but it sat straight upon the equipment section of the Agena.  The Ferret shrouds included a short cylindrical section (maybe 15-20 inches tall) below the cylindrical section.  Both shrouds had a similar brass color.

The April 1964 Thor Ablestar failure (Thor 379) is listed in Peter Hunter's records as having been caused by an incorrect switch position that caused "erroneous guidance signals to be sent to Thor".  This led to loss of control at some point during the ascent.  I don't know enough details about the guidance system to understand exactly what happened.  My understanding is that the Thor phase of flight was under the control of an autopilot rather than a guidance system.  The guidance system, which was on the Ablestar stage and was described as a "lightweight" guidance system assembled under the guidance of Space Technology Lab (later The Aerospace Corp), would have taken control after the first couple minutes of flight, or perhaps not until after staging.  At that point, it would have been sending "guidance signals ... to Thor".  It was a may have been radio guidance or it may have been a simplified inertial system.  Thus If it was radio guidance, the "incorrect switch position" could have been at a ground-based guidance computer.  One description of this failure states basically that the wrong program was run.

EDIT:  A bit more information.  Guidance was a Space Technology Lab radio guidance system that used a Burroughs J-1 computer on the ground to integrate trajectory based on doppler shift measurements from a transponder on the vehicle.  Trajectory corrections were transmitted to the vehicle during the second stage of flight. 

I'm adding a couple of low resolution trims from the high resolution Peter Hunter images that are being steadily added to L2.  The Ferret example used an Agena B while Star Rad rode on an Agena D.

 - Ed Kyle
« Last Edit: 08/28/2016 07:46 PM by edkyle99 »

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