Jump to content

PGM-17 Thor

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by Audin (talk | contribs) at 02:08, 3 January 2004. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Note: this article is in its fact collection stage...


Thor was the United States's first operational ballistic missile. It was deployed with thermonuclear warheads in the U.K. between xx and xx. It went on to spawn a string of space launch vehicles, the decendants of which fly to this day as the Delta series of rockets.

Development of the Thor was initiated by the US Air Force in 1954 as a Tactical Ballistic Missile. The goal was a missile system that could deliver a nuclear warhead over a distance of 1150 to 2300 miles with a CEP of 2 miles. This range would allow Moscow to be hit from a launch site in the U.K.

The initial design studies were headed by Cmdr. Robert Truax (US. Navy) and Dr. Adolph K. Thiel (Ramo-Wooldridge Corp, formerly Redstone Arsenal). They refined the specs to an IRBM with:

  • A 1750 mile range
  • 8' diameter, 65' long (so it could be carried by Douglas C-124 Globemaster)
  • A gross takeoff weight of 110,000 lbs
  • Propulsion provided by half of the Navaho-derived Atlas booster engine (due, largely, to the lack of any alternatives at this early date)
  • 10,000 mph maximum speed during warhead reentry
  • AC Spark Plug inertial guidence system with radio backup (for low susceptability to enemy disruption)

On November 30, 1955 three companies were given one week to bid on the project: Douglas, Lockheed, and North American Avation. They were asked to create "a management team that could pull together existing technology, skills, abilities, and techniques in 'an unprecedented time.'" On December 27, 1955 Douglas Aircraft Corporation was awarded the prime contract for the airframe and integration. The Rocketdyne division of North American Avation was awarded the engine contract, AC Spark Plug the primary inertial guidance system, Bell Labs the backup radio guidance system, and General Electric the nose cone/reentry vehicle.

Douglas further refined the design by choosing bolted tank bulkheads (as opposed to the initially suggested welded ones) and a tapered fuel tank for improved aerodynamics. The engine was developed as a direct descendant of the Atlas [[MA-3 (rocket engine)|MA-3]] booster engine. Changes involved removal of one thrust chamber and a rerouting of the plumbing to allow the engine to fit within the smaller Thor boat-tail.


Thor missile development

First operational american ballistic missile.

Missile initiated in 1954 as a Tactical Ballistic Missile with range between 1150-2300 miles CEP 2 miles (thus it could reach Moscow from a launch site in the UK).

1955 became IRBM.

Initial IRBM design study headed by Cmdr. Robert Truax (US. Navy) and Dr. Adolph K. Thiel (Ramo-Wooldridge Corp, formerly Redstone Arsenal).

Initial numbers:

  • 8' diameter, 65' long (could be carried by Douglas C-124 Globemaster)
  • 1750 mile range
  • 10,000 mph max during reentry
  • gross weight 110,000 lbs (with fuel and warhead)
  • use half of the Navaho-derived atlas booster engine (due to lack of any alternatives)
  • AC Spark Plug inertial guidence system with radio backup (for low susceptability to enemy disruption)

Three companies challanged to bid on 30 Nov 55: Douglas, Lockheed, and North American. Given one week to reply. Contractor expected to create "a management team that could pull together existing technology, skills, abilities, and techniques in 'an unprecedented time.'" Douglas awarded contract on 27 Dec 55 for airframe and integration. Rocketdyne div of North American Aviation awarded engine contract, AC Spark Plug inertial guidance, Bell Labs backup radio guidance, GE nose cone/reentry shield.

XSM-75 -> WS-315A -> Thor.

Tapered fuel tank to improve aerodynamics, bolted tank bulkheads.

MB-3 engine is a direct decendant of the Atlas MA-3. Remove one thrust chamber, rerouted plumbing. Turbopump development problems. Engine tests as of march 56 at Santa Susana Mountains. First example engine in June. First flight engine in Sept 56.

101. First airfram, 101, Oct 56. First launch from LC17-B. Pad B completed just barely before flight. Atlas blockhouse design borrowed. Pad A not complete at first launch. First flight 25 jan 57. Apogee of 6 inches. Contamination destroyed a LOX supply valve to fail, causing engine to lose thrust. Vehicle slid back down onto pad and exploded on thrust deflector below launch table.

102. apr 57. 35 second flight. ended by range safety officer working from a faulty instrament which indicated an inbound flight, not outbound.

103. may 57. Exploded on pad during tanking due to faulty main fuel valve resulting in tank overpressurization leading to tank rupture.

104. aug 57. 92 seconds. broke up due to loss of guidance.

105. 20 sep 57. 21 months after start of construction. flew 1100 miles downrange. Removing weight of R&D instruments, range would be 1500 miles.

Later flights in 57 (10 all total) reached 2700 miles.

Deployed to UK in aug 58.

Atlas reentry system. Thor flew first, so tested atlas reentry vehicle designs.


June 4, 1962? A nuclear warhead atop a Thor rocket booster falls into the Pacific Ocean when the booster has to be destroyed.?

June 20, 1962 ? A second Thor rocket booster fails, and the nuclear device falls into the Pacific. ?


9jul62. Starfish Prime Event. Thor missile 195 launches Mk4 renentry vehicle containing W49 thermonuclar warhead to an altitude of 248 miles. Warhead detonates at altitude with yield of 1.45 MT. Dominic-Fishbowl.

Thor as launch vehicle

Thor Thor Able Thor Able Star Thor Delta Thor Agena A (Thor Hustler) Thor Agena B Thor Altair
Stage 1 Thor
MB-1
170,000lbf 		Thor
MB-1
170,000lbf 		Thor
MB-3
172,000lbf 		Thor
MB-3
170,000lbf 		Thor
MB-3
170,000lbf 		Thor
MB-3
170,000lbf 		Thor
MB-3
170,000lbf
Stage 2 - AJ10-42 AJ10-104 AJ10-118 Agena A Agena B X-248 (Altair)
Stage 3 - X-248 - X-248A5 - - -
Notes IRBM SLV, reentry vehicle test SLV SLV SLV SLV

116. Thor-Able. Carried Aerojet AJ-10-40 using Vanguard second stage engine (UDMH/inhubited white fuming nitric acid). Called Able. Three vehicles used to test GE advanced Atlas reentry vehicle. 116 lost due to turbopump failure in thor main engine.

"Bearing Walking" - movement of turbopump bearings axially in their mountings.

127. Thor-Able-Star. Three stage, Thor, Able I (upgraded), Altair X-248 solid upperstage. 84lbs Pioneer. Enter lunar orbit, take pictures with Tv camera. Launch 17 aug 58, exploded at 77 sec due to turbopump failure.

Thor-Agena

Developed for Corona program.

Thor as NASA vehicle

7 aug 59 Thor-Able III launches Explorer 6 to study Van Allen belts and take pictures with tv camera.

jan 59, The National Space Vehicle Program. "Our approach up to this ptime has been much too diverse in that we fire a few vehicles of a given configuration, most of which have failed to achieve their missions, and then call on another vehicle to take the stage. In this situation no one type of vehicle is tested with sufficient thoroughness and used in enough firiing to achieve a high degree of reliability."

Proposed four vehicles:

  • Vega: atlas + vanguard derived vehicle. never flew.
  • Centaur: First high-energy upper stage.
  • saturn I (rocket)
  • Nova (rocket), never flew. Prompted the development of the F-1 (rocket engine), which powered the Saturn V.
  • Delta: Based on Thor-Able. as "an interim general purpose vehicle" meant to be "used for communication, meterological, and scientific satellites and lunar probes during '60 and '61". To be replaced by Vega and Centaur when they came on-line. To emphasize reliability rather than performance by replacing components which have caused problems on Thor-Able flights. Name from radio code word for 'D', as it was the fourth alteration of Thor as a luanch vehcile behind Able, Able-Star and Agena. Variously known as Delta and Thor-Delta.

Original NASA Delta vehicle

april 59 nasa and douglas sign contract for development and production of 12 Delta launch vehicles.

Stage 1: Modified thor irbm. MB-3 Block I RP-1/LOX producing 152,000lbf. gas generator also lox/rp-1, exhaust out of pipe next to nozzle. Gimble mounted, two vernier for roll control.

Stage 2: Aerojet AJ-10-118, 7700lbf, UDMH/nitric acid. Pressure fed via helium. Gas jet attitude control system (had been deleted from earier variants of Able). Aerojet engine cost $4million to build, 4 times initial bid. Very reliable, still flying. Used Bell Labs BTL-300 radio guidance system.

Stage 3: 'Altair' Spin stabalized by turntable on top of second stage. Spun up to 100rpm by two solid rockets before seperation. Unguided otherwise. ABL X-248 solid rocket motor. 2800lbf for 38 seconds. weighed 500 lbs. Wound fiberglass casing.

Performance: place 650 lbs into leo of 115 to 230 miles or 100lbs to GTO.

11 of 12 flights successful. $43 million development and launch support cost. $3million over budget. Goddard spaceflight center orders 14 more deltas during <=62.

Flights:


1 13may60 9:16pm gmt. Payload: echo 1. pad 17a. Good first stage. second stage attitude control system failure. vehicle destroyed.
2 12aug60. good flight. echo 1A placed into 1035 mile, 47degree inclination orbit.
3 23nov60. Tiros 2. good lfight.
4 explorer 10. placed into elliptical 138,000 mile orbit. 78lbs.
5 12july61. tiros 3.
6 16aug61. explorer 12 Energentic Perticle Explorers. EPE-1. highly elliptical orbit.
7 8feb62. tiros 4.
8 7mar62. OSO-1 (orbiting solar observatory). 345 mile, 33 degree orbit.
9 26apr62. Ariel 1. Ariel 1 was seriously damaged by Starfish Prime
10 19jun62. tiros 5
11 10jul62. Telstar 1. Also damanaged by Starfish Prime.
12 18sep62. tiros 6

Delta Evolution

Delta A

Block II MB-3 engine, 170,000lbf vs. 152,000lbf.

13. EPE2

14. EPE3

Delta B

Upgraded AJ10-118D upper stage--3 foot tank stretch, higher energy oxidizer, solid-state guidance system. Delta program goes from 'interim' to 'operational' status. 200lbs to GTO.

15. 13dec62. Relay 1, second nasa communications sat. nasa's first active one.

16. 13feb63. pad 17b. Syncom 1. Thiokol Star 13B solid rocket as apogee kick motor.

20. july63? Syncom 2. Geosyncronous orbit, but inclined 33degrees due to the limited performance of the Delta.

Delta C

Third stage Altair replaced with Altair 2--its engine having been developed as the ABL X-258 for the Scout vehicle. 3" longer, 10% heavier, but 65% more total thrust.

Thrust Augumented Thor-Agena D

Developed to handle the growing recon sats of the Corona program. Three Castor solid rocket strapon boosters. 53,000lbf each. Lit on the grouns and jettisoned after burnout.

Delta D

Thrust Augumented Delta. A Delta C with the TAT core+boosters.

25. 19aug64. Syncom 3. First true Geosyncronous sat. 26. Intelsat 1

Delta E

Thrust Augumented Improved Delta. 1965. 100lbf more to GTO than Delta D. Castor II vs Castor boosters. Same thrust, longer duration. MB-3 Block III core engine, 2000 lbf more thrust. AJ10-118E second stage widened from 33 to 55 inches diameter. Double burn time. Additional helium tanks allow for almost unlimited restarts. Two available third stages: Altair 2 or FW-4D. The latter caused the delta to be known as a Delta E1. New payload fairing from agena.

First Delta E. 6nov65. launches GEOS 1.

Delta G

Two stage delta Es. used for Biosatellite 1 and 2 flights.

1. 14dec66. biosatellite 1. 2. 7sep67. biosatellite 2

Delta J

4jul68. Explorer 38. Used larger Thiokol Star 37D motor as third stage.

Long Tank Thor

Tapered fuel tank changed to cylinderical. Both tanks lengthened. Core stage 14 feet longer. 49,000lbs more propellant.

Delta L

FW-4d motor fir third stage.

Delta M

Star 37D for stage 3.

Delta N

Two stage version.

'Super Six'

Deltas with three extra strap ons. 1000lbs to GTO.

  • Thor from Encyclopedia Astronautica
Retrieved from "https://en.wikipedia.org/w/index.php?title=PGM-17_Thor&oldid=2072601"