The latest released photographs of the Shihab 3 missile show a new warhead shaped like early generations of US and Soviet warheads. This may indicates that intends to fit a new type of weapon into the Shihab 3 warhead.
On August 11th, Iran announced a test of a new version of the Shihab 3 missile, described by Iranian sources as "More accurate". Iran also released a video showing a missile taking off from a towed launcher indistinguishable from the Shihab 3 launchers paraded last year during the "Martyr's Day" celebrations. Somewhat confusingly, senior Iranian officials denied to Jane's Defense Weekly in its August 18th issue that the test involved a live firing, insisting that it had been merely a dry "Field exercise". Another source, the Website newsletter "Middle East New Line" (MENL), elaborates on the JDW disclosure, describing the test as a "Dry" field exercise of the entire Iranian command, control and communication (C3) structure - from political leadership down to the Iranian Revolutionary Guards troops that responded to an alert in the military base in Dasht-E-Kabir near Esfahan, took the Shihab3 missile from its silo and loaded it on the launcher.
The most surprising piece of information in this welter of confusing and contradictory reports about the events of August 11 is without doubt the ample video footage of the missile launch released by Iran. The silhouette of the ascending missile was new. From the reentry vehicle (RV) base down to the fins, the missile looked like the long familiar "Shihab 3" as seen in previous flight tests. The front section of the missile, however, was radically different. Instead of its usual 'Dunce Cap" RV of all the shihab missiles displayed to date (Figure 1 below), the August 11 images show a completely different RV, consisting of a conical front section, a cylindrical mid section, and a flared skirt at the rear section (Figure 2). This three-section geometry is remindful of the early single warhead RV's of both Superpowers during the 1960's - the "Baby Bottle" shape of the early Polaris and its Soviet equivalent, the SSN6 (R-27).
Close up images showed further details. The front end of the new RV sports a rather large hemispherical ablation nose tip. The front cone is made of two subsections, with slightly different cone angles. The cable raceway along the missile is longer than in previous version, and emerges from the rear skirt rather than from the missile itself, as in the previous version of the Shihab 3. All these indicate a completely redesigned RV, both externally and internally.
Changing the configuration an RV is not trivial. It impacts on the controllability of the entire missile during its boost phase, and on the trajectory, dynamics and viability of the RV during re entry. It even affects the range to some extent. Hence, if the Iranians decided to take this step, they must have had compelling reasons to do so. Once compelling reason would be the installation of a new weapon with a center of gravity (CG) well to the aft. The weapon may require an instrument section of its own, for safety, arming and fusing (Hence the elongated cable raceway), which would move the CG of the whole RV even further to the back. With the CG of the payload moved significantly rearward, a purely conical RV could lose stability. A sharp angled "Skirt" or flare at the rear of the RV corrects this problem by moving the center of pressure (CP) to a point behind the new CG, recovering the aerodynamic stability of the whole assembly. To obtain such a flare, the mid section of the RV must be made cylindrical or nearly so, with a diameter that would allow sufficient flaring towards the RV base section. The Iranian images leave an impression that the diameter of the cylindrical section in the new RV is about 2/3 of the basic diameter of the Shihab 3. Thus, the upper limit on the diameter of the weapons for which the new RV is designed is about 0.8 meters.
The new RV 's aerodynamic drag is probably higher than that of the previous configuration, which could reduce the range slightly. On the other hand, it could be considerably more stable, justifying the Iranian claim that the missile is "More accurate".
The new shape will cause a modest forward shift of the CP of the whole missile. This might pose a control problem towards the end of the boost phase, when the CG of the missile travels well forward. There is little doubt that the Iranians had to redo some of the missile's control programming in order to accommodate the new RV and regain the original flight characteristics. That they managed to do so shows that the control system is programmable - another indication that the Shihab 3 avionic suit is probably more sophisticated than the hardwired gyro - cum- mechanical clockwork of the original SCUD family.
The existence on the new RV is not necessarily an indication that a new weapon is already operational. At the least, however, it indicates that the weapon's systems architecture, geometry, weight and balance have been defined, and that an integrated system engineering effort of the weapon/missile assembly is now proceeding towards detailed design and implementation. Testing the new RV at such an early stage would be needed to obtain flight data and verify design parameters.
Taken together, the new RV plus the Iranian's deliberate disclosure of its existence are fraught with significance. First, it indicates that the Iranian's have frozen an overall design of a definitive Shihab 3 payload. Second, it stands to reason that the payload is not a simple charge of explosives - such a charge could simply be cast into the front end of the previous warhead, rather than undertaking the complicated route of reshaping the RV to fit the weapon. Third, it discloses a respectable degree of proficiency in missile engineering (Or access to such proficiency). Fourth, it tells something about the missile's level of sophistication. Fifth, the release of the such an extensive and detailed photographic material is by itself a clear message, not only of self-confidence, but also of warning: The Shihab 3 is approaching maturity not only as a missile, but also as an integrated weapon system. Clearly, Iran is sending here a powerful warning, and is willing to show its hand to do so. That she decided to broadcast such a forceful message at this time indicates a serious measure of concern and alarm on Iran's side.
Is the new RV an indigenous Iranian design? This is hard to say. A new RV design requires not only proficiency in the relevant engineering disciplines, but some considerable infrastructures including, among other important installations, a hypersonic wind tunnel. The Iranians may have achieved indigenous proficiency since acquiring the original No Dong from North Korea. Past media reports claimed that Iran received missile knowhow from Russia. This could still be going on. It may be significant that Pakistan's Ghauri missile, another version of the ubiquitous No Dong, retains it "Dunce Cap" warhead in all images released by Pakistan to date. On the other hand, there have been persistent reports about a new North Korean long-range missile. Some of those reports spoke about a "Baby Bottle" shaped missile. Does this new Iranian "Baby Bottle" missile indicate that the design came from North Korea? Or that Iran is helping North Korea by testing her missiles on Iranian soil? There is no evidence to date to confirm or dismiss such speculations.
The claim that the August 11th event was a "Dry" rather than a "Live" test is in apparent contradiction to the release of flight images. Perhaps the flight shown in the images did not take place on August 11th, but earlier. The Iranian's pattern of test information disclosure is not consistent. In some cases, announcement of flight tests were accompanied by extensive video footage. In other occasions, no images were released. Perhaps the August 11th release is of a previously undisclosed test material.
Yet there may be another explanation to this apparent contradiction. It is tempting to speculate the there was indeed a national level command and control exercise, but that it culminated not in a dry run by with a live test of a new version of the Shihab3. This would better explain the description of satisfaction by the "Entire Iranian leadership" who "Attended the test" and felt they had "broken a new ground", as described in MENL. It is hard to see the Iranian leadership wasting their time or exhibiting such a degree of enthusiasm over a relatively lackluster dry run of C3 and logistics systems. This speculation is reinforced by the August 11 images (Figure 3). The missile is seen taking off from a launcher deployed in a ravine, with the typical dry vegetation of Middle Eastern summertime covering the slopes. The launcher is position in a small patch of excavated ground bulldozed clean of vegetation, to reduce the risk of the vegetation catching fire from the missile's rocket motor. The photographic evidence does not show any tracking instrumentation on the surrounding hills. The location is obviously not a test range launch pad, but rather a carefully selected operational launch point, with the ravine's slopes offering a measure of protection from hostile air attack. In this sense, the test was indeed a "Field Exercise", as claimed by the Iranian officials.
There is yet one more clue in the released images. The launch seems to have taken place not far off from a body of water, which can be seen in the far distance in Figure 2. It stands to reason that the Iranians fire their missiles overland, to locate the impact point and measure accuracies. Hence, the body of water can't be the Persian Gulf or the Indian Ocean, but rather a lake. There is one sizable lake west of the city of Esfahan, in the Zagros Mountains. If the launch point was located on the north shore of that lake, the range to an impact point in Iranian Baluchistan could be about 750 miles, or 1200 Km - a satisfactory range for a command performance for the national leadership. According to the Israeli Ha'aretz daily (August 20), the test was not successful. This might explain the backpedaling of Iranian officials, who initially labeled the even as "A Test" (A term hitherto reserved exclusively for live tests) and later downplayed it into an "Operational Exercise". In the past, the Iranians were reluctant to admit failures in the Shihab 3 program.
There can be little doubt that the August 11th test was highly significant, whatever sequence of events actually took place. Iran displayed an advanced missile capability and was willing to sacrifice military secrecy to do so. In showing her hand to technical audiences in the West, Iran sent a powerful - and perhaps a frantic - message. In all, the impression is of a tense leadership, striving to avert a perceived danger toitself, nervously brandishing all its swords to ward off an imagined impending attack.