Thor Booster Variants

[leovinus]

i found program called Thor-Ophos

it's German 1960s project for high energy stage to be launch on Thor booster.
(how far this project is involved in German licence build Thor-deltas, i don't Know)

OPHOS abbreviation for "Optimierte Hochenergetische Stufe" (eng: Optimized Highenergetic [Rocket]stage)
and was proposed by Bölkow GMBH (other source Bölkow Entwicklungen KG) later MBB
the studies began in 1961
it had pressure fed engine with radial thrust chamber and E-D nozzle delivers 39,000N (8,800 lb) thrust.
And use a fluorine/hydrogen propellant combination as for Thor

Proposed version:
OPHOS I E (fluorine/hydrogen) pressure feed Isp Vac = 475 sec
OPHOS II E (hydrogen/oxygen) pressure feed Isp Vac = 455 sec
OPHOS III P (hydrogen/oxygen) turbopump feed Isp Vac = 462 sec

seems that OPHOS IIIP was proposed as Third stage of Europa Rocket.

Source
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19710065891_1971065891.pdf

Nice, but the NTRS link does not seem to work :/
Attached a few pages from "Missiles and Rockets" with an Ophos mention.

[Blackstar]

I'm at Vandenberg. Found these. Have not checked to see if they are in the Peter Hunter collection.

[WallE]

Thor 354, which gained some notoriety. It was the maiden flight of the Thrust Augmented Thor featuring three Castor SRMs and it was carrying a CORONA KH-4. One of the SRMs failed to start at liftoff. The Thor lifted from SLC-1E (aka LC-75-3-5) and steered downrange but eventually the dead weight of the non-operative SRM dragged it off course and the Range Safety destruct command was sent at T+127 seconds. The cause of the failure was a simple mistake by a technician during prelaunch preparations--he forgot to connect the electrical umbilical attaching the SRM to the main LV, thus it had no power and could not operate.

The prevailing winds blew the cloud from the explosion of the Thor east over Arizona where it was seen and widely reported on, including in a LIFE Magazine article. There had also been an Atlas launch on February 28, 1963 when Missile 188D performed a successful Nike-Zeus target missile test. The next two TAT launches failed as well, in less dramatic fashion, and the fourth attempt on May 18 finally succeeded.

Pictured above we see Thor 296 and 327. The first successfully launched Discoverer 18 on December 7, 1960. The second launched Discoverer 37 on January 13, 1962 but the Agena engine failed to start and orbit was not attained.

The failure rate of Thors used on military programs in this period was unacceptably bad compared to civilian Deltas although to be fair they did also outnumber Delta 3-1. Nonetheless, the 3/19/64 Explorer launch attempt was only the second unsuccessful Delta launch and there had been 22 successes in a row prior to it.

[catdlr]

Jun 17, 2025  CAPE CANAVERAL
Rare photos from our archive, a look at our two THOR rockets in Hangar C and more!  Yes, it's time to get to know THOR!

[catdlr]

[WallE]

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.  Despite several subsequent cleanup efforts, Johnston Atoll, managed by the U.S. Fish and Wildlife Service since 2000, is still affected.

Bluegill Prime must be easily one of the top five rocket disasters of all time. What specifically happened is that the LOX valve only opened part-way at engine start, preventing combustion and mainstage operation from taking place. RP-1 continued to enter the combustion chamber and started a fire from contacting the hot engine. After burning for several seconds, the RSO blew up the warhead. Note that the warhead and missile had separate flight termination systems and only the former was actually activated. The warhead destruct nonetheless ruptured the fuel tank below it and caused all its contents to spill out in a huge fireball. As you will see in the video, the lower portion of the Thor continued to burn for a bit more time until the LOX tank ruptured. Postflight examination of missile hardware found that foreign debris had blocked up part of the pneumatic control lines and prevented the main LOX valve from opening properly.



Initially the fire is mostly fuel-rich and at 0:07 it looks like some of the LOX ducting in the thrust section ruptured as it gets a lot more LOX rich at that point.

[WallE]

Video of the 9-18-68 Delta failure, caused by an open circuit in the pitch gyro that led to loss of control. Pitch oscillations that began shortly after liftoff can be seen and right before destruct they appear to have lost T/M data. This was most likely due to booster tumbling which caused the T/M antennas to lose their lock on the ground; that can also be noted in the videos of GOES-G where they announce that they lost T/M once it started tumbling.

NASA Deltas overall were super reliable compared to Air Force Thors and no Delta experienced a first stage failure until this one. One story I heard was that NASA played it conservatively and avoided using certain high performance missile parts that were prone to reliability issues.

[WallE]

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.

The ground guidance station transmitted error commands to the Thor as someone set a switch on a console incorrectly a result of which the missile was directed to point downward and to the left of nominal. The upper stage separated and began its burn on time but was facing the wrong direction and ended up sending the Transit satellite into the Pacific Ocean rather than orbit. Thor worked similar to Atlas in that the early part of the launch was autopilot only and it would later enable guidance steering commands. And yes it was radio guidance like all SLV Thors; only the missile variant used inertial guidance.

[catdlr]

Family Tree

https://forum.nasaspaceflight.com/index.php?topic=59222.msg2719835#msg2719835

[Blackstar]

LB posted this upthread, but I'm reposting. Jim knows a lot of missile men, so maybe he can confirm if their heads are always this flat.

[Jim]

LB posted this upthread, but I'm reposting. Jim knows a lot of missile men, so maybe he can confirm if their heads are always this flat.

I knew a lot of missilers.   They were like moles, squinty eyed from the sunlight and poor social skills due to being under ground.  They were horrible instructors at Officer Training School because they were frakked at the world for their bad career choices.