Author Topic: Thor Booster Variants  (Read 22539 times)

Offline edkyle99

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Re: Thor Booster Variants
« Reply #60 on: 12/21/2016 08:16 PM »
Extended Long Tank (ELT) Delta flew 93 times from 1972 until 1990, succeeding 89 times and orbiting all manner of important payloads. 

Extended Long Tank included a roughly 120 inch first stage tank stretch compared to the Long Tank stage.  It flew with both MB-3-3 and RS-27 engines.  Rocketdyne's RS-27 was essentially a repackaged H-1 engine salvaged from the large inventory of unflown Saturn IB engines. A total of 83 RS-27 engines flew.

Three different second stages flew atop ELT Deltas. 

The first was the AJ10-118F powered stage that was a holdover from Long Tank Delta. It was topped by the  65 inch diameter Agena shroud. 

The second was powered by the TR-201 TRW Lunar Module descent engine derivative.  This stage was the first to be suspended within an extended interstage cylinder, through the use of a "Miniskirt".  The design allowed use of a 96 inch diameter payload fairing.  It was informally named "Straight Eight" because, for the first time, the entire launch vehicle had a constant eight foot diameter.

The third was the AJ10-118K powered "ITIP" (Improved Transtage Injector Program) stage that began flying in 1982.  This stage used fatter tanks originally developed for Japan's N-2 launch vehicle.  Today's Delta 2 second stage is similar.

Spin-stablized Star 37D, 37E, and 48B third stage motors flew atop ELT Deltas aimed beyond LEO.  During the Shuttle era when Delta served as an STS backup, NASA carded Delta 3910/PAM-D and Delta 3920/PAM-D variants.  The PAM stage, a Star 48B spin-stable solid motor, was considered part of the "payload" just as it was on Shuttle. 

Delta 147, launched on December 17, 1978, used the first Delta Redundant Inertial Measurement System (DRIMS).  DRIMS improved the inertial measurement unit introduced with DIGS, but kept the DIGS guidance computer.  DRIMS added redundancy on all axes of motion.

ELT Delta's used the four-number model identification system.

                        Delta Model Numbers

        First Digit:  First Stage and Strap on Motor Types

        0:  Long Tank, MB-3-3 engine, Castor 2 motors (1968)
        1:  Extended Long Tank, MB-3-3 engine, Castor 2 motors (1972)
        2:  Extended Long Tank, RS-27 engine, Castor 2 motors (1974)
        3:  Extended Long Tank, RS-27 engine, Castor 4 motors (1975)
        4:  Extended Long Tank, MB-3-3 engine, Castor 4A motors (1989)
        5:  Extended Long Tank, RS-27 engine, Castor 4A motors (1989)

        Second Digit:  Number of Strap on Motors

        Third Digit:  Second Stage Type

        0:  AJ10-118F (Aerojet Transtage derivative, 1972)
        1:  TR-201 (TRW LM Descent Engine derivative, 1972)
        2:  AJ10-118K (Aerojet ITIP engine, 1982)

        Fourth Digit:  Third Stage Type

        0:  No third stage
        3:  Star 37D (TE-364-3, 1968)
        4:  Star 37E (TE-364-4, 1972)
        5:  Star 48B (TE-M-799, 1989)

 - Ed Kyle
« Last Edit: 02/04/2017 03:18 AM by edkyle99 »

Offline edkyle99

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Re: Thor Booster Variants
« Reply #61 on: 01/11/2017 08:27 PM »
Thor Burner 2A could not lift DMSP 5D1, a much upgraded, heavier military weather satellite.  Two Star 37 upper stage motors were needed to reach orbit.  Thus, the final five Thor LV-2F flights, launched between September 11, 1976 and July 14, 1980, flew as Thor Star 37/Star 37/ISS launch vehicles.  "ISS" stood for "Integrated Stage System", a hydrazine-based propulsion system on the satellite that provided 3-axis control during the solid motor burns and a final trim burn.  A Star 37XE motor served as the second stage while a Star 37S-ISS acted as the third stage.  A longer payload fairing with a blunter nose housed both stages and the payload.  The upgraded launch vehicle could lift roughly 500 kg to the DMSP sun synchronous orbit.   

The first four launches were good, but the July 14, 1980 finale was a disheartening failure.   Refurbished IRBM Thor 304 flew true, and the first Star 37 burn looked good, but at Stage 3 startup all telemetry was lost.  It was subsequently determined that connectors between the second and third stages had not disconnected due to a misalignment.  When the Star 37S motor ignited, the wiring harness was jerked out of the third stage and satellite, killing the flight control system.  The stage pitched down and failed to generate sufficient orbital velocity.  It turned out that an incident during launch vehicle erection - a broken pin that caused the rocket to suddenly drop a few centimeters - had most likely caused the connector misalignment.

Thor 304 was the final Thor IRBM to fly, and the final launch from Space Launch Complex 10 West. 

 - Ed Kyle
« Last Edit: 01/12/2017 01:19 PM by edkyle99 »

Offline edkyle99

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Re: Thor Booster Variants
« Reply #62 on: 02/05/2017 02:53 AM »
From 1975 through 1992, it was possible to see "Delta" lookalike rockets liftoff from Tanegashima, Japan.  A total of 24 Thor-based rockets, assembled in Japan under license from the U.S., flew for the National Space Development Agency of Japan (NASDA). There were three variants, all unique to Japan.

N-1 ("N" stood for "Nippon"), launched from 1975 through 1982, was an MB-3-3 powered Long Tank Thor Delta with three Castor 2 boosters.  An MHI built LE-3 pressure-fed hypergolic engine powered the second stage.  A Star 37N solid motor served as the third stage.  An Agena shroud topped the rocket.  N-1 could lift 1.2 tonnes to LEO or 0.36 tonnes to GTO.  It flew 7 times with one failure.  Notable successes included Japan's first geostationary orbit launch, of Kiku 2 (ETS-2) on February 23, 1977.   The lone failure occurred on February 6, 1979 when the fifth N-1's Star 37N third stage collided with its Experimental Communications Satellite (ECS-A) satellite payload shortly after spacecraft separation.

N-2, which flew 8 times during 1981-87, used an MB-3-3 powered Extended Long Tank Thor stage augmented by nine Castor 2 strap on motors.  The second stage was powered by a restartable Aerojet AJ10-118FJ pressure-fed engine (after NASDA's planned LE-4 engine stumbled during development).  The stage used new fatter tanks that would later be adopted by NASA's 3920 series and later Deltas, including today's Delta 2.  Star 37E served as a third stage motor.  N-2 used DIGS inertial guidance.  It could lift 2 tonnes to LEO or 0.73 tonnes to GTO.

H-1, which flew 9 times during 1986-92, introduced a new NASDA-developed common bulkhead liquid hydrogen fueled second stage that was powered by a brand new NASDA-developed LE-5 engine built by MHI and IHI.  The rocket was controlled, for the first time, by an inertial guidance system developed in Japan. H-1 could lift 2.25 tonnes to LEO or 1.1 tonnes to GTO. 

For a time during the post-Challenger accident period, McDonnell Douglas considered adopting Japan's upper stage, or at least the LE-5 upper stage engine, for use on U.S. Delta launch vehicles.

 - Ed Kyle
« Last Edit: 02/05/2017 01:59 PM by edkyle99 »

Offline Michel Van

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Re: Thor Booster Variants
« Reply #63 on: 02/05/2017 05:29 PM »
hi Ed Kyle

There were also another nations interested in license Delta rocket

Delta Made in Germany
Germany look into option to build license or buy Delta rocket during 1960s early 1970s
But I have not solid information about model, who gonna build it, how they want to launch from were.
It's very likely they had to launch from Cape Kennedy.

Source
Several German space books mention the German license Delta rocket
but just a sentence, not further information.

Europa Deltas
ESRO look after the Europa  fiasco for a alternative for launching there Satellite
in 1974 they contacted McDonnell/Douglas  for order on Delta 2314, 2914 and 3914
and construction of Delta launch pad on Kourou space port to be ready in 1977
The French Government and CNES were not amused of this Idea of ESRO...

Source in French language
http://www.capcomespace.net/dossiers/espace_europeen/ariane/ariane1/naissance_1970_1975.htm

Offline edkyle99

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Re: Thor Booster Variants
« Reply #64 on: 02/14/2017 02:20 PM »
Happy Delta 2 Day everyone!

The first Delta 2, a 6925 model with nine Castor 4A SRMs, the first Extra Extended Long Tank first stage, an AJ10-118K powered second stage, a Star 48B third stage motor, and a 9.5 foot diameter metal fairing, orbited GPS-2 1 from Cape Canaveral LC 17A on Valentine's Day (February 14) in 1989.  This was Delta 184, the first of 49 Delta 2 GPS launches, 48 of which would succeed.

I'm working on a Delta 2 (EELT) card, which I'll post here soon.

 - Ed Kyle
« Last Edit: 02/14/2017 02:39 PM by edkyle99 »

Offline edkyle99

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Re: Thor Booster Variants
« Reply #65 on: 02/15/2017 02:24 PM »
During the mid-1980s, McDonnell Douglas shut down the long-running Delta production line as NASA moved payloads to Space Shuttle.  The 1986 Challenger disaster changed everything.  Soon, the U.S. Air Force was asking for an expendable launcher that could orbit the GPS satellites originally slated for STS.  McDonnell Douglas won the resulting Medium Launch Vehicle competition over General Dynamics (Atlas K), Martin Marietta (Titan 3 Commercial), and Hughes (Jarvis).

After pondering use of Japan's H-1 liquid hydrogen upper stage, McDonnell Douglas pulled an early 1980s proposal off the shelf to create "Delta 2".  The rocket was built around a stretched "Extra Extended Long Tank" first stage that was 148 inches longer than the "Extended Long Tank" version.  It carried 96 tonnes of propellant, a 16 tonne increase.

The first, interim Delta 6000 series vehicles used RS-27 engines and upgraded steel-case Thiokol Castor 4A strap on motors.  The ultimate Delta 7000 series rockets used new RS-27A engines that were more efficient in vacuum and new GEM-40 Graphite Epoxy Motors developed by Hercules.  All versions used the existing Aerojet AJ10-118K ITIP-powered second stage.  Star 48B served as the third stage for GPS missions.  A new 9.5 foot diameter standard fairing housed most payloads.  The old 8-foot fairing flew a few times.  McDonnell-Douglas also developed a 10 foot diameter metal shroud based on the company's Titan 3C fairing.

Delta 2 initially used the existing DRIMS guidance and control system, but on December 30, 1995 Delta 230 became the first to use the Redundant Inertial Flight Control Assembly (RIFCA).  RIFCA, built around six ring laser gyroscopes and six accelerometers, provided triple redundant guidance, flight control and mission sequencing functions.

The first Delta 2, a 6925 identified as Delta 184, orbited GPS-2 1 from Cape Canveral LC 17A on February 14, 1989.  Seventeen  6000-series Deltas flew.  Delta 212, the last in 1992, was the final flight of a Saturn H-1 derived RS-27 engine.  Delta 201, the first 7925, orbited the first of the heavier GPS-2A satellites on November 26, 1990.  All told, Delta 2 performed 49 GPS launches with one failure.

In December 1994, NASA requested bids for a Medium Light Expendable Launch Vehicle (Med-Lite).  McDonnell-Douglas's offered Delta 732X and 742X, which used three and four GEM-40 boosters respectfully.  In 1997 a new 10 foot diameter composite payload fairing (10C) began flying for Iridium.  A stretched 10L version was developed for NASA beginning in 2002, ending use of the Titan-derived fairing. 

From 1989 through 2011, Delta 2 was the most often-flown, versatile, productive, and reliable U.S. launch vehicle.  It became the longest-lived essentially unchanged U.S. launcher, even though its ownership and production sites moved twice.  It flew from three launch pads at two launch sites.  It was common to see multiple Deltas stacked simultaneously.  151 Delta 2 rockets flew by the end of 2011 with two failures, making Delta 2 one of the most successful orbital launchers in history.  In addition to its bread-and-butter GPS work, Delta 2 orbited commercial, non-U.S. government, and NASA satellites. 

For NASA, Delta 2 did something no previous Thor/Delta had done - it reached into deep space, to Mars, and to asteriods.  The list of payloads includes Mars Pathfinder, Odyssey, Spirit, Deep Impact, and many others.  Commercial payloads included Iridium and Globalstar "little LEO" satellites.

In 2003, Delta 7920H and 7925H began flying.  They used powerful GEM-46 solid rocket motors reassigned from the terminated Delta 3 program (about which more soon).  They launched the Opportunity Mars rover, the SIRTF/Spitzer space telescope, the planet Mercury orbiter MESSENGER, asteroid Vesta and Ceres orbiter Dawn, gamma ray telescope GLAST, and lunar orbiters GRAIL A and B.

Although Delta 2's Cape launch site was closed after 2011, the Delta 2 story is not over.  Two more launches from Vandeberg AFB SLC 2W remain on tap.  If both succeed - never a given - the rocket's consecutive success string would reach 100.

 - Ed Kyle
« Last Edit: 03/16/2017 02:55 AM by edkyle99 »

Offline Jim

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Re: Thor Booster Variants
« Reply #66 on: 02/15/2017 02:52 PM »
Ed, the 10 foot composite fairing was developed for Iridium.  The long composite was developed for NASA.

Offline edkyle99

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Re: Thor Booster Variants
« Reply #67 on: 03/16/2017 02:52 AM »
During the post-Challenger era, McDonnell Douglas studied liquid hydrogen fueled upper stages for its Delta launch vehicle.  In 1986, it briefly considered  Japan's H-1 LH2/LOX upper stage for the U.S. Air Force Medium Launch Vehicle (MLV) program before deciding on the "Delta 2" approach.  Two years later, it proposed a new LH2/LOX upper stage to be built by Martin Marietta for the MLV-2 program (won by GD Atlas 2).  The company continued to study the idea until, on May 10, 1995, it announced that it would develop "Delta 3" using more than $200 million of its own funds, with a planned first launch in 1998.

Soon, Delta 3 held contracts for 18 launches through 2002, including NASA/NOAA GOES N, O, and P and five ICO Global Communications launches.

Delta 3 used a 4 meter diameter "Delta Cryogenic Upper Stage" (DCUS) and more-powerful Alliant 46 inch diameter Graphite Epoxy Motors (GEM-46) to lift the heavier stage and payload.   The first stage had a shorter but fatter kerosene fuel tank (4 meters rather than 2.4 meters diameter) so that Delta 3 would fit within the Delta 2 service tower.   A Pratt & Whitney RL10B-2 engine with a large Snecma-built extendible nozzle powered DCUS.  At liftoff, the boosters and RS-27A main engine would together produce more than 1 million pounds of thrust.  The rocket could lift 3.8 tonnes to GTO.
 
Delta 3 was assembled in Pueblo, Colorado.  Japan's Mitsubishi Heavy Industries made the 4 meter diameter second stage liquid hydrogen tank and first stage kerosene tank using tank tooling from its H-2 stage. 

On December 15, 1996, McDonnell Douglas and Boeing announced their intention to merge under the Boeing name.  The merger was consummated on July 1, 1997.  The merger would have decisive consequences for the Delta 3 program, though that was not initially apparent.

A relatively smooth development program was followed by a troubled flight program.  Delta 259, the first Delta 3, launched from Cape Canaveral SLC 17B (the only pad rebuilt for the type) on August 27, 1998 with the Galaxy 10 communications satellite.  At about T+50 seconds, the rocket began to suffer 4 Hertz roll oscillations, using up the GEM-46 TVC hydraulic fluid.  The rocket pitched over and broke apart at T+72 seconds.  Flawed roll control equations were found to be the cause.
 
The second Delta 3, Delta 269, launched with the Orion 3 communications satellite on May 5, 1999.  This time the flight proceeded flawlessly through the first RL10B-2 burn, pushing the stage and payload into a parking orbit. After a coast period, the RL10B-2 engine restarted for a planned 162 second burn, but it shut down after only 3.4 seconds, stranding Orion 3 in LEO.  An investigation found that the RL10B-2 engine's combustion chamber had burst during the restart due to defective brazing of a welded reinforcing strip.  Pratt & Whitney subsequently modified its brazing process and its inspection methods.

Delta 3 finally succeeded on August 23, 2000 when Delta 280 launched the 4,348 kg DM-F3 mass simulator to subsynchronous transfer orbit.  By then, however,  Boeing was committed to its Sea Launch commercial launch partnership and had begun to develop Delta 4 for the EELV program.  In 2000, Boeing bought Hughes Space & Communications, the satellite builder that held the bulk of the Delta 3 backlog.  Then the commercial satellite market collapsed, leaving Boeing deeply overextended.  Something had to give, and the first of those somethings was Delta 3, which was quietly shut down after Delta 280.

In the end, Delta 3's primary accomplishment was to prove RL10B-2 in flight for Delta 4, and to prove DCUS, which was the first all-new high energy upper stage developed in the U.S. since the 1960s.  The Delta 4 Medium "Delta Cryogenic Second Stage" was largely derived from DCUS.

This should end the "as-flown" portion of this thread.  It only took eight months to get here!

 - Ed Kyle
« Last Edit: 03/16/2017 08:45 PM by edkyle99 »

Offline ZachS09

Re: Thor Booster Variants
« Reply #68 on: 03/31/2017 09:43 PM »
Wasn't there a Delta II 7930 design conceptualized? It was supposed to be like a Delta II 7920, except that the hypergolic-fueled second stage was replaced by the larger LH2-fueled second stage. This is NOT the Delta III I'm referring to, because according to http://www.spacelaunchreport.com/thorh13.html:

"Designers initially contemplated a "Delta 7930" design similar to the MLV II bid.  It was a Delta 2 with a 3.2 meter diameter liquid hydrogen second stage powered by a single RL10 engine.  This rocket would have been able to lift 2.6 tonnes to GTO.  It also would have adhered to Delta's long-term incremental growth tradition."

If this 7930 design DID fly, then the interstage of the first stage would have to be modified to fit the larger diameter of the second stage.
« Last Edit: 04/01/2017 02:35 AM by ZachS09 »
"Liftoff of Falcon 9: the world's first reflight of an orbital-class rocket."

Offline brickmack

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Re: Thor Booster Variants
« Reply #69 on: 04/02/2017 04:44 AM »
I found this on my computer. Can't find anything else, but it does show there was some work put into it. Also wondering about that double-barrel version. Also found mention of a Delta III variant using 3 large SRMs in place of the GEMs, and a Delta Lite using a Delta K with 2 of those large SRMs serving as first and second stage (looked about the size of Castor 120, MD's version of Athena?)

Offline edkyle99

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Re: Thor Booster Variants
« Reply #70 on: 04/02/2017 06:25 PM »
I found this on my computer. Can't find anything else, but it does show there was some work put into it. Also wondering about that double-barrel version. Also found mention of a Delta III variant using 3 large SRMs in place of the GEMs, and a Delta Lite using a Delta K with 2 of those large SRMs serving as first and second stage (looked about the size of Castor 120, MD's version of Athena?)
This image came from a February 1990 article in Flight International by Tim Furniss, which can be found here:
https://www.flightglobal.com/FlightPDFArchive/1990/1990%20-%200300.PDF

This article ran about a year-and-a-half after McDonnell Douglas had offered an RL-10 upper stage based bid for MLV II, a contract won by General Dynamics Atlas II.  These early studies eventually led to the 1995 decision to develop Delta III.  Interestingly, Delta III ended up with about the performance shown for the right-most "double-barrel" design in the article.  McDonnell Douglas got there by using more powerful GEMs rather than two RS-27A stages strapped together!

 - Ed Kyle
« Last Edit: 04/03/2017 04:01 PM by edkyle99 »

Offline edkyle99

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Re: Thor Booster Variants
« Reply #71 on: 05/24/2017 02:31 AM »
I've compiled the flown Thor variant "baseball cards" here.
http://www.spacelaunchreport.com/thorflew.html
also accessible here
http://www.spacelaunchreport.com/thorh.html
and here
http://www.spacelaunchreport.com/library.html

 - Ed Kyle

Offline WallE

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Re: Thor Booster Variants
« Reply #72 on: 05/24/2017 12:15 PM »
Ed might want to fix his page on Atlas orbital failures because the link has been broken for months.

Offline edkyle99

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Re: Thor Booster Variants
« Reply #73 on: 05/24/2017 01:40 PM »
Ed might want to fix his page on Atlas orbital failures because the link has been broken for months.
Thanks.  Should be there now.  Feel free to contact me offline, by email, for things like this.

 - Ed Kyle

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Re: Thor Booster Variants
« Reply #74 on: 05/26/2017 09:45 PM »
I've compiled the flown Thor variant "baseball cards" here.
http://www.spacelaunchreport.com/thorflew.html
also accessible here
http://www.spacelaunchreport.com/thorh.html
and here
http://www.spacelaunchreport.com/library.html

 - Ed Kyle

Can I stick this launch vehicle baseball cards in the spokes of my  bike wheels? ;D

Offline WallE

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Re: Thor Booster Variants
« Reply #75 on: 07/24/2017 06:01 PM »
The first Fishbowl launch was a successful R&D flight with no warhead.  The second launch, carrying an active warhead, was "lost" by a defective range safety tracking radar and had to be destroyed 10 minutes after liftoff.  Three subsequent Thors, all carrying nuclear warheads, suffered propulsion system failures and had to be destroyed by range safety.  Two of those destructions occurred downrange, a minute or more into flight, dropping some radioactive contamination on and near Johnston Island.  The third failure, on July 25, 1962, was a true Cold War disaster.

No missile parts were recovered from "Bluegill" and the debris dispersal of the warhead was not tracked. Although it was far out to sea and radioactive material did not reach land, there were nonetheless several Navy ships in the area.

The 6/20/62 attempt was known as "Starfish" and it must be one for the record books. The dummy RVs mounted to the Thor caused the turbine exhaust to be deflected back up into the thrust section, heating and softening the engine mounts until they failed, at which point the engine broke loose and rammed into the LOX tank above. The Thor broke up 59 seconds into launch, and the RSO destruct command was sent six seconds later, destroying the warhead and raining down plutonium. Navy divers recovered 251 missile parts from the shallow waters around Johnson and Sand Island, some of which were contaminated with radioactive material.

Thor 180, the missile for that "Bluegill Prime" shot attempt, was fitted with a W50 thermonuclear warhead capable of producing a 400 kiloton explosion.  A  propellant valve stuck at ignition, causing a leak that fed a rapidly expanding fireball that enveloped Thor on its launch pad.  The range safety officer fired the destruct system, destroying the Thor, the warhead, and the launch emplacement, which burned for some time, contaminating the island.

On "Bluegill Prime", what happened was that the Thor's main LOX valve only opened part-way, which prevented the engine from achieving stable mainstage combustion. It apparently lifted about a quarter to half an inch before settling back down on the pad. At this point, RP-1 spilling into the hot combustion chamber started a fire. The Range Safety Officer was also an inexperienced newbie, and he should have actually just sent the manual cutoff command which would close the RP-1 valve and stop the flow of fuel that was feeding the fire. Instead, he issued the destruct command and blew the entire missile up. The video of Bluegill Prime is on Youtube, it's pretty crazy. The RSO destruct ruptures the Thor's fuel tank and explodes the warhead, but the LOX tank and thrust section are still intact. After a few more seconds, the LOX tank goes up in a ball of white flame.

After that, "Bluegill Double Prime" was to take place on September 23, but concern over Wally Schirra being exposed to high altitude radiation on his Mercury flight delayed the test until October 16. The Thor suffered a flight control system failure at 85 seconds and did a cartwheel before being finally destroyed by RSO action at 156 seconds. At this point, the Air Force were ready to tell Douglas that their rocket was a piece of junk and they needed to find some other option. Unfortunately, there weren't many other choices. Redstone lacked the range needed for the tests and Polaris was too new and not many of them were available, also it needed extensive modifications for the mission.

Thor was given one last chance and "Kingfish" succeeded on November 1. In the end, the failures don't seem to have been the fault of the Thor itself, which was highly reliable by 1962, but radar tracking problems and the pods attached to the base of the missiles which were adversely affecting their aerodynamic profile.

Offline fs10inator

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Re: Thor Booster Variants
« Reply #76 on: 08/01/2017 09:54 PM »
I wanted to add a little, but probably worthwhile note on the LE-3:

The engine was tested in space by mounting the LE-3-powered second stage to a M-3C rocket. This combination was called the Engineering Test Vehicle, and flew the LE-3 twice to test its performance, once in 1974, and once again in 1975.

Note the N-1 MST in the background.

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Re: Thor Booster Variants
« Reply #77 on: 10/11/2017 04:42 PM »
Delta A introduced MB-3 Block 2 engines that produced 170 klbf liftoff thrust.  Delta A, which flew twice in 1962, also featured a shorter interstage between Thor and Able to shave weight.  The improved Delta actually stood 4 to 5 feet shorter than the original Thor-Delta. 
 - Ed Kyle
Coming back to this topic one year late. But I think it's better to ask here than in the Q&A section. I'm trying to go in to the details of the Delta-A development. Couldn't find much info at NTRS, DTIC and the open archives. So here some of the points which are giving me a serious headache:
I have see different statements regarding the Delta-A guidance. Some say it still used a BTL-300, others BTL-600.
I have been reading again and again that Delta-A's second stage had restart capability. True or not? If yes it seems that there was no need to use it for the HEO of Explorer IX and XV. (How about Delta-B?)
Missiles and Rockets (Sept 24th, 1962) stated that Delta-A (and maybe Delta-B) used RJ-1 fuel instead of RP-1. True? If so, when this was reverted to RP-1?
Same source (see here https://archive.org/details/missilesrockets1119unse - search for 'reliable delta') states 1st stage thrust as 165k lbf. Usually one can read of 170k lbf. Maybe interim for DSV-2A only?
Geschichte und Geschichten aus sechs Jahrzehnten Raumfahrt:
http://www.raumfahrtkalender.de

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