{"id":285033,"date":"2010-02-05T17:11:05","date_gmt":"2010-02-05T22:11:05","guid":{"rendered":"tag:www.armscontrolwonk.com,2010-02-05:57f256023a9af1385990be02cc9db91e\/6fecc357739a25c0b579c7ced8170f1d"},"modified":"2010-02-05T17:11:05","modified_gmt":"2010-02-05T22:11:05","slug":"iran%e2%80%99s-missile-development-trajectory-75","status":"publish","type":"post","link":"https:\/\/mereja.media\/index\/285033","title":{"rendered":"Iran\u2019s Missile (Development) Trajectory [75]"},"content":{"rendered":"

Iran\u2019s aerospace program has been so active in the last few years <\/a> it should be possible to say something about their development philosophy: the technological arc or trajectory they are following. For instance, why did they \u201cjump\u201d from SCUD<\/span>-type missiles to the Shahab-3-type? Why didn\u2019t they put a higher priority on clustering engines in order to achieve greater ranges before moving on to the Shahab-3? Many of my friends believe they should have. A large portion of their argument is centered on the fact that they believe Iran would have established a missile capable of hitting Israel much sooner if they had done that, perhaps as early as the mid-1990s. Of course, such arguments place an extraordinary amount of emphasis on such a military objective, especially when Iran\u2019s nuclear program was much, much less advanced.<\/p>\n

I\u2019ve always thought, however, that Iran did make a strategic decision about the direction its missile development program was going in. But it was not a military-strategic decision but an industrial-strategic decision even if there were military advantages to be had further down the road. I believe Iran decided they needed to assimilate the technology for producing large engines indigenously and that this was a much higher priority for them than early production of a longer range missile. New images released at the same time as the \u201cKavoshgar-3\u201d sounding rocket (with its animal passengers) was launched. Two amazingly important images were released:<\/p>\n

\"\"
\nA new, large, two-stage rocket with the Iranian space agency logos on it. The second stage appears to be the same stage (and nose fairing) as the Safir\u2019s second stage.<\/em><\/p>\n

Assuming that the smaller diameter second stage is the same as the Safir\u2019s second stage (with a diameter of 1.25 meters), then the much larger first stage is consistent with a diameter of 1.95 meters. That is, of course, considerably smaller than twice the Shahab-3\u2019s diameter of 2 times 1.25 (or 2.5) meters. So it is fair to ask \u201cWhat can you put in there?\u201d I think the answer is a cluster of four \u201cNodong engines.\u201d And, voila, the Iranians show a new rocket power plant with a cluster of four Nodong engines at the same gathering where Pres. Ahmadinejad watched the Kavoshgar-3 launch:<\/p>\n

\"\"
\nAn Iranian rocket scientist unveils the new cluster of four Nodong engines, known as the Phoenix (if Google translate is working properly). The yellow struts above the engines are for transmitting the thrust to the rocket’s airframe. Their presence implies that the first stage will use jet vanes for thrust vector control.<\/em><\/p>\n

Phoenix, the name of the new power plant, is an interesting name. I’m not sure what the Iranian mythological implications are but as a Westerner, to me it means rebirth in fire. Perhaps they are implying the rebirth of this engine design in a new form. Of course, it is always dangerous to use one cultural point of view to analyze another culture\u2019s literary allusions. <\/p>\n

The yellow struts rising above the engine cluster (and their multiple turbopumps, perhaps four? one for each engine?) are for fastening the power plant to the rocket body and for transmitting the thrust they develop. They are angled slightly outward for increased structural strength. Pads at the top of the struts are the connections with corresponding strong points inside the first stage. But is the first stage wide enough to accommodate this cluster?<\/p>\n

To answer that question, I have had to go through a chain of photo-interpretation; each of which undoubtedly contributes a certain amount of uncertainty or error to the final answer. First, I had to determine the diameter of the Nodong engine. (I know these are Shahab-3 engines, but I am so used to calling them Nodongs, it would be too painful to switch. Let it be known that I think these engines are indigenously produced in Iran, though Iran probably bought or licensed the production line for them from North Korea.) I get a diameter for the combustion chamber, just below the strong points for the struts, of 0.57 m.<\/p>\n

Then, transfer this diameter to the image of the Phoenix power plant:<\/p>\n

\"\"
\nThe top of the Phoenix power plant, showing the combustion chambers and the full diameter of the struts. Calculations by the author indicate that this cluster of four engines would certainly fit inside the large rocket body shown above.<\/em><\/p>\n

Using this combustion chamber diameter as a reference point on length, I get a total separation between opposite pads at the top of the struts of 1.87 meters. Of course, a rather long chain of analyses was needed to estimate this length. And even the assumption that the farthest right strut pad and the farthest left strut pad represent the full diameter of the support system introduces a certain amount of uncertainty (though that is reduced by a cosine theta effect). Nevertheless, this is remarkably close to my estimate for the diameter of the new rocket\u2019s first stage. Close enough to convince me that this is the new first stage\u2019s power plant.<\/p>\n

Note that there are at least superficial differences between this rocket\u2019s first stage and the DPRK\u2019s U’nha-2\u2019s first stage. If nothing else, Iran has designed the airframe itself. (I am being extra cautious about this, my own feeling is that Iran has designed the entire first stage itself. But that is such a key step in my understanding of Iran\u2019s missile development trajectory, that I am hesitant to state it as a conclusion.)<\/p>\n

So what do I think has happened? First, Iran purchased a production line for Nodong engines (and the other components of the Shahab-3 missile) from North Korea. However, though the years of producing them, flight testing Shahabs, and modifying them with the design and production of the Safir and other rockets, Iran has fully assimilated this technology <\/a> and they are moving on to the next stage of development\u2014clustering large engines (they obviously gained some highly important experience with the cluster of two engines on the Safir\u2019s second stage)\u2014 and they are probably doing this largely on their own.<\/a><\/p>\n

Note: a future post will estimate the range of this missile using the “hypothesis” developed here.<\/p>\n

<\/p>\n","protected":false},"excerpt":{"rendered":"

Iran\u2019s aerospace program has been so active in the last few years it should be possible to say something about their development philosophy: the technological arc or trajectory they are following. For instance, why did they \u201cjump\u201d from SCUD-type missiles to the Shahab-3-type? Why didn\u2019t they put a higher priority on clustering engines in order […]<\/p>\n","protected":false},"author":5379,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-285033","post","type-post","status-publish","format-standard","hentry","category-news"],"_links":{"self":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/posts\/285033","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/users\/5379"}],"replies":[{"embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/comments?post=285033"}],"version-history":[{"count":0,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/posts\/285033\/revisions"}],"wp:attachment":[{"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/media?parent=285033"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/categories?post=285033"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mereja.media\/index\/wp-json\/wp\/v2\/tags?post=285033"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}