Notes and references
- Gronlund , Lisbeth and Wright , David . 1992 . “Depressed Trajectory SLBMs,” . Science & Global Security , 3 (1–2) : 101 The computer calculations are performed by integrating the equations of motion of the missile on a round, non‐rotating earth in the presence of an atmosphere (for the level of accuracy considered here, the effects of the earth's rotation on missile range can be ignored). The drag coefficient of the missile as a function of speed during boost phase is approximated by using measured values for the V‐2 rocket. For additional details see appendix B of
- Lewis , John W. and Di , Hua . 1992 . “China's Ballistic Missile Programs: Technologies, Strategies, Goals,” . International Security , 17 fall : 32
- Bermudez , Joseph Jr. 1990 . “New Developments in the North Korean Missile Programme,” . Jane's Soviet Intelligence Review , August : 343
- Bermudez , Joseph Jr. 1993 . “Ballistic Ambitions Ascendant,” . Jane's Defence Weekly , 10 April : 20
- 1988 . "Ballistic Missiles in the Third World,” . International Defense Review , November : 1423 Several sources report that North Korea acquired the Scud‐Bs from the Soviet Union. Steven Zaloga states they were acquired in the mid‐1970s
- Koptev , YA. 1993 . “How to Save the Russian Rocket Industry,” . Rossiyskiye Vesti [Moscow] , 17 August : 7 in FBIS‐SOV‐93–158, 18 August 1993, p. 9). Bermudez reports they were acquired from Egypt in the early 1980s ("Ballistic Ambitions").
- Throughout this paper, we follow the naming convention for North Korean missiles from Bermudez, “Ballistic Ambitions,” with the replacement of “NKScud” for “Scud” to distinguish them from variants of the Soviet Scud missiles.
- Bermudez, “Ballistic Ambitions.”
- In addition, Bermudez ("New Developments") states that one of the design parameters for the DF‐61 program in the mid‐1970s was a heavy‐gauge skin to protect the missile from damage during transport and handling, since the missile was to be mobile. This report suggests that the North Koreans would use steel for their other mobile missiles as well.
- Bermudez, “New Developments.”
- Sutton , George P. 1986 . Rocket Propulsion Elements , (fifth edition) , 40 New York : John Wiley and Sons . See for example,
- Lennox , Duncan . 1991 . “Inside the R‐17 ‘Scud B’ Missile,” . Jane's Intelligence Review , July : 302
- Lenhart , Warren and Masse , Todd . 14 February 1991 . Persian Gulf War: Iraqi Scud Ballistic Missile Systems , Congressional Research Service Report 91–173 F 14 February , 6
- 1991 . “Race To Find Iraq's ‘Scuds’ “ . Jane's Defence Weekly , 26 January : 91
- Cochran , Thomas . 1989 . Nuclear Weapons Data‐book Volume IV: Soviet Nuclear Weapons , 221 New York : Ballinger/Harper and Row . Bermudez, “Ballistic Ambitions”;
- Carus , W. Seth and Bermudez , Joseph S. Jr. 1990 . “Iraq's al‐Husayn Missile Programme,” . Jane's Soviet Intelligence Review , May : 204
- Lennox , Duncan . 1991 . “Iraq's ‘Scud’ Programme,” . Jane's Defence Weekly , 2 March : 301
- Jameson , Sam . 1993 . “North Korea Test Missile Able To Reach Japan,” . Washington Times , 12 June : A13 Bermudez, “Ballistic Ambitions.”
- 1991 . Milavnews , March : 23 Reported range/payload combinations are 500 kilometers/700 kilograms (Bermudez, “Ballistic Ambitions"); 550 kilometers/600 kilograms
- Emerson , Steven . 1991 . “The Postwar Scud Boom,” . Wall Street Journal , 10 July 640 kilometers/680 kilograms
- Lenhart and Masse . Persian Gulf War 6 Our estimate of the CEP for the separated warhead agrees well with estimates given for the Iraqi al‐Hussein missile: the Congressional Research Service gives a value of one to 1.5 miles (1,600 to 2,415 meters)
- 1992 . Patriot Performance Assessment in Desert Storm Roadmap , 15 July : 10 and Jane's Defence Weekly reports 1,600 to 3,200 meters ("Race To Find Iraq's ‘Scuds’ “). This estimate also appears to be consistent with data presented in the unclassified pages of the U.S. Army report
- The durability of the engine may limit how much the amount of fuel may be increased beyond that carried by the Mod‐C. Increasing the fuel increases the length of time the engine is burning and therefore subjects the engine to greater heating, which the cooling system on relatively simple engines like the Scud may not be able to withstand without modifications. The configuration of the al‐Hussein may suggest that the burn time, and thus the fuel, cannot be increased by more than about 25 percent. Iraq also reportedly built a missile called the al‐Abbas with 40 percent more fuel than the Scud‐B and a range of 900 kilometers with a 350 kilogram payload (Lennox, “Iraq's ‘Scud’ Programme"). However, it was not used in the 1991 Gulf War and there are indications that it may have had operational difficulties.
- According to figure 2, reducing the structural weight of the Mod‐C by roughly 450 kilograms, which would result from replacing the steel body with aluminum, would give a range of less than 600 kilometers with a one tonne payload.
- Yong‐Chin , Nan . 1991 . “DPRK's Advanced Weapons Analyzed,” . Nuclear Developments , 31 May : 7
- 1991 . Hanguk Ilbo [Seoul] , 8 February : 8 Bermudez, “Ballistic Ambitions.”
- 1991 . “DPRK Reportedly to Build New Scud Missile,” . Nuclear Developments , 24 June : 7
- 1991 . Yonhap [Seoul] , 3 June
- Seib , Gerald . 1992 . “Missile Race in Mideast, Along With Nuclear Issue, Raise Concern,” . Wall Street Journal , 8 June : A6 Emerson, The Post‐war Scud Boom”;
- Gertz , Bill . 1991 . “Libya May Buy North Korean Missiles,” . Washington Times , 4 June : 4 Libya will reportedly pay $7 million each for the missile
- Reuters wire service, 18 April 1993.
- 1993 . Yonhap (Seoul) , 14 July in FBIS‐EAS‐93–134, 15 July 1993, p. 18;
- Wolfs‐thal , Jon . 1993 . “U.S. Prods Israel to Halt Talks with North Korea on Missile Sales,” . Arms Control Today , September : 24
- Fulghum , David . 1993 . “Mideast Nations Seek to Counter Air Power,” . Aviation Week and Space Technology , 7 June : 77
- Sanger , David . 1993 . “Missile is Tested by North Korea,” . New York Times , 13 June : 7
- Anderson , Jack and Binstein , Michael . 1992 . “North Korea: Loose Nuclear Cannon,” . IAEA (International Atomic Energy Agency) Daily Press Review , 31 March : 12
- Gertz , Bill . 1992 . “Iran‐Bound Mystery Freighter Carried Parts for Missiles,” . Washington Times , 16 July : A3
- Lim , C.W. 1993 . “North Korean Tells of Nuclear Accident,” . Washington Times , 25 August : A1 In 1990, construction of two bases for intermediate‐range missiles was reported near the Demilitarized Zone
- Gertz , Bill . 1991 . “Libya May Buy North Korean Missiles,” . Washington Times , 4 June : 4 Guam is 4,000 kilometers from North Korea.
- 1991 . Tbng‐a Ilbo (Seoul) , 25 August Bermudez ("Ballistic Ambitions") notes reports of a test failure in 1991 and a successful test (although not to full range) somewhat later. Other reports of a successful test prior to May 1993 include Gertz “Libya May Buy North Korean Missiles”;
- 1993 . “Defense Ministry Says May Nodong‐1 Test Successful” . Yonhap (Seoul) , 24 June in FBIS‐EA, 26 August 1991;
- 1993 . “North Korea Seen Successful in Test of Nodong‐1 Missile,” . Aerospace Daily , 29 June : 538 in FBIS‐EAS‐93–120, 24 June 1993, p. 19;
- Pitman , Joanna . 1993 . “Worried Tokyo May Buy Patriot Defense,” . Times (London) , 12 June For reports that no previous tests had occurred see
- Gertz , Bill . 1993 . “General Spotlights North Korean Threat,” . Washington Times , 15 September : A6 Sanger, “Missile Is Tested.” Reports that a Nodong exploded on the launch pad in May 1990
- Gertz , Bill . 1990 . “North Korean Missile Apparently Blows Up,” . Washington Times , 5 July apparently refer to U.S. satellite evidence
- Katell , Andrew . 1993 . “North Korea Suspends Move to Quit Nuclear Arms Pact,” . Boston Globe , 12 June : 4 Reuters wire service, 11 June 1993;
- Jameson . 1993 . “North Korea Test Missile” . Seoul KBS‐I Radio , 1 June
- 1993 . Yonhap (Seoul) , 15 June in JPRS‐TND‐93–018, 14 June 1993, p. 3;
- 1993 . “North Korea Seen Successful in Test of Nodong‐1 Missile,” . Aerospace Daily , 29 June : 538 in FBIS‐EAS‐93–113, 15 June 1993, p. 28;
- 1993 . Aviation Week and Space Technology , 5 July : 17
- 1993 . Yonhap (Seoul) , 14 July in FBIS‐EAS‐93–134, 15 July 1993, p. 18; Gertz, “General Spotlights Threat.”
- “Japan Says North Korea to Finish Missile Soon,” Reuters wire service, 11 November 1993.
- 1993 . “Defense Ministry Says May Nodong‐1 Test Successful” . Yonhap (Seoul) , 24 June in FBIS‐EAS‐93–120, 24 June 1993, p. 19; Sanger, “Missile Is Tested.”
- 1993 . “Official Confirms North's Mobile Test Launch,” . Choson Ilbo (Seoul) , 3 December : 1 in FBIS‐EAS‐93–231.
- Gertz, “General Spotlights Threat.”
- 1993 . Kyodo (Tokyo) , 12 June in FBIS‐EAS‐93–112, 14 June 1993, p. 5; UPI wire service, 14 June 1993;
- 1993 . Yonhap (Seoul) , 15 June in FBIS‐EAS‐93–113, 15 June 1993, p. 28.
- Platkovskiy , A. 1991 . “North Korea Nuclear Program Viewed,” . Nuclear Developments , 12 September : 24 Range estimates appear to be based on the size and fuel capacity as derived from images of the missile. References include:
- 1991 . Komsomol‐skaya Pravda [Moscow] , 24 August
- 1991 . Kyodo (Tokyo) , 20 September
- 1991 . Proliferation Issues , 29 October : 7
- Lewis , Paul and Silverberg , David . 1992 . “West Worries China Will Sell Missiles,” . Defense News , 16 March : 1
- Seib , Gerald . 1992 . “Missile Race in Middle East Countries Despite U.S. Efforts to Stall Buildup,” . Wall Street Journal , 8 June : A6
- Katell . 1993 . “Nor Korea Suspends Move” . Aviation Week and Space Technology , 5 July : 17
- Sieff , Martin . 1993 . “Israel to Woo North Korea to Keep Missiles From Iran,” . Washington Times , 15 June : A8
- 1993 . “DPRK Reportedly Boosts Range of Nodong, Sells to Iran,” . Yonhap (Seoul) , 8 June in JPRS‐TND‐93–018, 14 June 1993, p. 27;
- Chang‐sun , Yi . 1993 . “Japan's Sense of Terror for Nodong‐1,” . Sinmun (Seoul) , 13 June : 7 in FBIS‐EAS‐93–112, 14 June 1993, p. 31; “North Korea Seen Successful,” Aerospace Daily.
- Since the combustion chamber and nozzle of the Scud‐B engine are roughly 0.4 meter in diameter there is room to cluster four of them in the 1.2 to 1.3 meter body diameter of the Nodong (estimates of engine size were derived from photographs provided by Israeli journalist Reuven Pedatzur of an Israeli Defense Force display of al‐Hussein wreckage in Tel Aviv).
- The fuel and oxidizer in these missiles were each stored in a single large tank; the Soviet design used a single large turbo pump that fed fuel to all four engines, but the Chinese version used a separate small pump for each engine (Hua Di, private communication).
- Hua Di, private communication.
- 1993 . Yonhap (Seoul) , 14 July Nan Yong‐Chin, “DPRK's Advanced Weapons Analyzed” gives values of 15.1 meters in length and 1.3 meters in diameter. The article states a range of 600 kilometers, which does not appear to be consistent with the dimensions. The author may have assumed the missile was a Mod‐C rather than a Nodong, the author may have intended a range of 600 miles rather than 600 kilometers.
- We assume here that the same fuel and oxidizer are used as in the Mod‐B and Mod‐C and are used in the same proportions.
- Ed Blanche, Associated Press wire service, 22 October 1993; Reuters wire service, 28 October 1993.
- It is possible North Korea might test the missile with a very small payload to suggest a greater range capability than it actually had,
- Lewis and Di, “China's Ballistic Missile Program.”
- Lewis and Di, “China's Ballistic Missile Program.” China switched to stabilized platform guidance in the late 1970s with the development of the DF‐5/CSS4.
- 1993 . Yonhap (Seoul) , 14 July in FBIS‐EAS‐93–134, 15 July 1993, p. 18.
- 1993 . Chicago Sun Times , 20 April : 46 reported that Iran stopped shipping oil to North Korea in 1992 after the Scuds it had received (presumably Mod‐Bs or Cs) were found to be defective.
- Emerson , Tony . 1993 . “Nuclear Nightmare,” . Newsweek , 29 November : 20 Bermudez “Ballistic Ambitions”;
- Lewis and Di, “China's Ballistic Missile Programs.”
- This calculation assumes the first stage is made of steel to provide the structural strength to support the second stage, and has a fuel fraction of 0.8. The second stage fuel fraction is 0.77. If the fuel fraction of the second stage could be increased to 0.80 to 0.81 (for example, by using aluminum alloy for the body) the range would increase to 1,950 to 2,050 kilometers.
- 1993 . "North Korean Missile Eyed With Skepticism,” . Aviation Week and Space Technology , 18 October : 101 Some Japanese military officers are reportedly skeptical that North Korea's current technical and industrial capabilities are sufficient to produce such a missile
- Hoffman , David . 1993 . “Israel Agrees to Suspend Contacts with North Korea,” . Washington Post , 17 August Following the reported test of the Nodong missile in May of this year, Israel held three meetings with North Korea to discuss economic aid in return for commitments not to sell the missile to countries in the Middle East. Israel suspended the meetings under pressure from the U.S.
- Wolfsthal , Jon . 1993 . “U.S. Prods Israel to Halt Talks with North Korea on Missile Sales,” . Arms Control Today , September : 24
- Sanger , David . 1993 . “New Missile Defense In Japan Under Discussion with U.S.,” . New York Times , 18 September : 1 In addition, Japan has begun to consider developing or buying tactical missile defenses
- Opall , Barbara and Usui , Naoaki . 1993 . “Japan, U.S. Pursue Ballistic Missile Defense,” . Defense News , 4 October : 3
- Finnegan , Philip . 1991 . “Gulf War Exposes Effectiveness of Countermeasures,” . Defense News , 12 August : 1
- Postol , Theodore . 1991/92 . “Lessons of the Gulf War Experience with Patriot,” . International Security , 16 (3) winter : 119
- Lewis , George and Postol , Theodore . 1993 . “Video Evidence on the Effectiveness of Patriot During the 1991 Gulf War,” . Science & Global Security , 4 (1) : 1
- Bunn , Matthew . 1988 . “The Next Nuclear Offensive,” . Technology Review , January : 28 A bent nosetip on the MaRV produced the same type of lateral accelerations that the Nodong warhead would experience (see for example
- A Nodong warhead with a ballistic coefficient of 72,000 N m‐2 (1,500 lb ft‐2) would have a speed 30 to 60 percent faster than the al‐Hussein missile at altitudes of 10 to 30 kilometers, resulting in lateral forces 70 to 250 percent greater.
- Fetter , Steve . 1991 . “Ballistic Missiles and Weapons of Mass Destruction,” . International Security , 16 summer : 5
- Fetter , Steve , Lewis , George and Gronlund , Lisbeth . 1993 . “Why Were Scud Casualties So Low?” . Nature , 361 28 January : 293
- Lennox , Duncan . 1991 . “Inside the R‐17 ‘Scud B’ Missile,” . Jane's Intelligence Review , July : 302 This article contains a number of detailed photographs of the missile, which were used to derive some of the dimensions of the missile used below.
- The export version of the Scud‐B, the R‐17E, may use UDMH fuel with N2O4 rather than IRFNA as the oxidizer. The density of N2O4 is 1.44 g cm‐3 and the optimum mass ratio (N2O4/UDMH) is about 2.6. Four tonnes of propellant would therefore have a volume of 3.4 m3. Using N2O4 could increase the specific impulse by several per cent compared to using IRFNA. Assuming N2O4 is used instead of IRFNA would make only small changes in our model and would not affect our conclusions. In particular, the estimated length of the Nodong would increase by 0.5 meters, and the booster mass would increase by about 60 kilograms.
- Huzel , Dieter K. and Huang , David H. 1992 . Modern Engineering for Design of Liquid‐Propellant Rocket Engines , 20 Washington DC : AIAA . IRFNA III‐A is 83.4 percent HNO3 and 14 percent NO2, and IRFNA IV HDA is 54.3 percent HNO3 and 44 percent NO2. The optimal mass ratios (IRFNA/UDMH) for these two oxidizers are 3.13 and 2.85, respectively. The density of UDMH is 0.789 g cm‐3 and for IRFNA (III‐A) is 1.57 g cm‐3
- This ratio agrees with Carus and Bermudez's claim that the al‐Hussein tanks were increased by 0.45 and 0.85 meters over the Scud‐B (Carus and Bermudez, “Iraq's al‐Husayn Missile Programme"). The ratio may be increased above optimum to keep the combustion chamber from overheating.
- These quantities are related by the expression, where T is thrust in newtons, g0 is 9.8 m sec is specific impulse in seconds, is the propellant mass in kilograms, and, is the booster burn time in seconds.
- Carus and Bermudez, “Iraq's al‐Husayn Missile Programme.”
- Gronlund and Wright . “Depressed Trajectory SLBMs” . Science & Global Security , 3 (1–2) See equations (D‐3) and (D‐4) in
- It is equivalent, but simpler, to do this calculation using the two components of burnout velocity as we do here rather than using the magnitude and direction of the burnout velocity, which is more standard.
- We ignore the other contributions to guidance and control errors, such as errors in the burnout height, which will give small contributions to the total.
- Platus , D.H. 1977 . “Dispersion of Spinning Missile due to Lift Non‐Averaging,” . AIAA Journal , 15 July : 909 Net lift forces can occur even if the reentry vehicle is spinning (see, for example,
- Daniels , Doreen H. April 1965 . Ballistic Correlation Altitudes for Reentry Winds and Nonstandard Air Densities , April , Dahlgren, Virginia : U.S. Naval Weapons Laboratory . Using a constant perturbation whose magnitude is chosen to give the observed dispersion is a standard technique used to estimate the effects of other atmospheric effects on reentry dispersions (see, for example,
- This is illustrated by the difference in CEPs of the two cases calculated for the Mod‐C missile. While increasing the reentry speed increases the lift forces acting on the warhead, which are proportional to V2, it also reduces the time these forces act on the warhead, which leads to smaller dispersions. The calculations for the two Mod‐C cases assume that the magnitude of the lift coefficient is the same in both cases; as discussed below, however, increasing the ballistic coefficient may give rise to additional lift forces.
- Hall , D.W. and Nowlan , D.T. 1978 . “Aerodynamics of Ballistic Reentry Vehicles with Asymmetric Nosetips,” . Journal of Spacecraft and Rockets , 15 January/February : 55 For a discussion of some of these issues, see
- Kobayashi , W.S. and Saperstein , J.L. 1982 . “Low‐Temperature Ablator Tests for Shape‐Stable Nosetip Application on Maneuvering Reentry Vehicles,” . In Thermophysics of Atmospheric Entry , Edited by: Horton , T.E. 148 New York : American Institute of Aeronautics and Astronautics .
- Sellars , J.R. 1961 . “Reentry and Recovery,” . In Ballistic Missile and Space Systems , Edited by: Seifert , H.S. and Brown , K. 452 New York : John Wiley & Sons .
- This value of β is large because the weight of the reentering warhead and attached missile body is large. It assumes a value of the drag coefficient of 0.2
- The drag and ballistic coefficients are related by, where Cd is the drag coefficient, is the acceleration of gravity, is the mass of the warhead, and A is the cross‐sectional area of the warhead perpendicular to the direction of motion.
- Regan , Frank J. 1984 . Re‐entry Vehicle Dynamics , 230 New York : American Institute of Aeronautics and Astronautics .