02.10.2004, 01:02
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Zitat:The feasibility of a Shihab 3 based satellite launcherFoto IRIS-Launcher : <!-- m --><a class="postlink" href="http://www.me-monitor.com/files/Shihab3basedsatellitelauncher_files/image002.jpg">http://www.me-monitor.com/files/Shihab3 ... age002.jpg</a><!-- m -->
By Israel Briman and Arie Malta
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In 1998 Ali Shamkarni, the Iranian Minister of Defense, claimed that the next Iranian missile (dubbed Shihab-4 by Western observers) and following the recently tested 1300 km Shihab–3, was actually a satellite launcher. Various sources have further described the Iranian satellite to be a reconnaissance or communications satellite. Iranian television even showed a mockup of the Iranian satellite and the satellite launcher (see the accompanying photo). The word IRIS is shown painted on the satellite launcher model.
Based on the enclosed photo, and assuming that the model of the launcher is interdimensionally correct, we performed an analysis of the orbital launch capabilities of the (presumed) IRIS satellite launcher. This computation was based on following engineering assumptions, partly evident from the photo and partly based on known Iranian rocket technology and on averaged numbers for the physical characteristics of the pertinent rocket motors that are openly published:
The length to diameter ratio of the IRIS launcher is about 12.
The launcher has 3 rocket stages.
All rocket stages use liquid propellant.
All stages have the same diameter.
A careful study of the photo indicates that the fins at the bottom of the launcher are very similar to those used in the NoDong / Shihab-3 ballistic missiles. The Shihab-3 fins include jet vanes, typical of German / early Soviet rocket designs
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It was thus initially assumed that the IRIS satellite launcher uses the NoDong liquid propellant rocket engine and the 1.3 – 1.35 m diameter NoDong / Shihab-3 fuel and oxidizer tanks[i] for the first stage. This first stage would carry about 13 tons of liquid propellant, most probably composed of Nitric Acid and kerosene, as oxidizer and fuel respectively. Based on the 1:12 diameter to length ratio, the two upper stages of the launcher could carry up to 6.0 and 1.5 tons of propellant respectively. Factoring in the weight of the structure, tankage and the rocket motors themselves, the IRIS satellite launcher would then have a launch-weight of about 24-25 tons.
Using a specific impulse[ii] of 230 seconds at sea level (the standard value for this propellant combination) and an acceptable motor performance, the 95 sec burning NoDong engine generates about 29 tons of take-of-thrust. As noted below the NoDong engine is sometimes presented with 110 sec burning time: generating only 26 tons of take-off-thrust. We assume that the same liquid rocket engine is used in the second stage. The third stage motor is to be activated after throwing away the (by then) superfluous guidance and control electronics package, and the satellite fairing, shown in the picture. According to analysis such an IRIS launcher could place about a 5 kg satellite into a Low Earth Orbit (LEO). This definitely is not the satellite depicted in the photo.
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