{"id":188858,"date":"2010-07-18T05:47:00","date_gmt":"2010-07-18T10:47:00","guid":{"rendered":"https:\/\/www.panix.com\/~msaroff\/40years\/2010\/07\/18\/sorry-but-the-numbers-do-not-work\/"},"modified":"2010-07-18T05:47:00","modified_gmt":"2010-07-18T10:47:00","slug":"sorry-but-the-numbers-do-not-work","status":"publish","type":"post","link":"https:\/\/www.panix.com\/~msaroff\/40years\/2010\/07\/18\/sorry-but-the-numbers-do-not-work\/","title":{"rendered":"Sorry, But the Numbers Do Not Work"},"content":{"rendered":"

The USAF is looking at an air launched missile to intercept ballistic missiles during boost phase<\/a>. (paid subscription required<\/span>, but you can find a shorter version here<\/a>)<\/p>\n

Raytheon is pitching something called the Network-Centric Airborne Defense Element (NCADE), a, “two-stage missile with an extended-range Amraam solid-fuel rocket motor as the first stage, a separation joint, and a second stage with a divert attitude control system and guidance-unit electronics and an AIM-9X seeker.”<\/p>\n

It’s unclear to me what the range would be, but an AIM-9X (Sidewinder) missile seeker head does give us an idea as to the maximum speed of the missile: about Mach 2.5, about 850 m\/s, because of the hemispherical seeker head at the front of the missile. (see picture of AIM-9X forebody courtesy of Wiki)<\/p>\n

Beyond that speed, the drag, to say nothing of the heat generated, would be excessive.<\/p>\n

It’s why higher speed radar guides missiles have a conical or ogival nose cone.<\/p>\n

Well, if we work with the basic information for the launch performance of a Minuteman ICBM, 2 Gs at launch, this gives you 42 seconds until the ICBM is flying faster than the interceptor.<\/p>\n

In reality, the time for the ballistic missile to reach mach 2.5 would be less, as acceleration increases as fuel is burnt.<\/p>\n

This is not a viable interception time unless you know exactly<\/span> when and where the launch is occurring, and you are close enough to make the intercept within 30 seconds from launch, about 25 km.<\/p>\n

Also note that the Minuteman is an old missile, and newer designs, such as the now retired LGM-118A Peacekeeper, flew out faster, and were ejected from the silos with an expulsion charge at a not insignificant speed, so the interception time is realistically far less than 30 seconds.<\/p>\n

This really does not sound to me like a viable platform.<\/p>\n","protected":false},"excerpt":{"rendered":"

The USAF is looking at an air launched missile to intercept ballistic missiles during boost phase. (paid subscription required, but you can find a shorter version here) Raytheon is pitching something called the Network-Centric Airborne Defense Element (NCADE), a, “two-stage missile with an extended-range Amraam solid-fuel rocket motor as the first stage, a separation joint, …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1096,1025],"tags":[],"class_list":["post-188858","post","type-post","status-publish","format-standard","hentry","category-missile-defense","category-technology"],"_links":{"self":[{"href":"https:\/\/www.panix.com\/~msaroff\/40years\/wp-json\/wp\/v2\/posts\/188858"}],"collection":[{"href":"https:\/\/www.panix.com\/~msaroff\/40years\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.panix.com\/~msaroff\/40years\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.panix.com\/~msaroff\/40years\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.panix.com\/~msaroff\/40years\/wp-json\/wp\/v2\/comments?post=188858"}],"version-history":[{"count":0,"href":"https:\/\/www.panix.com\/~msaroff\/40years\/wp-json\/wp\/v2\/posts\/188858\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.panix.com\/~msaroff\/40years\/wp-json\/wp\/v2\/media?parent=188858"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.panix.com\/~msaroff\/40years\/wp-json\/wp\/v2\/categories?post=188858"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.panix.com\/~msaroff\/40years\/wp-json\/wp\/v2\/tags?post=188858"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}