Why the Ares 1-X test ISN'T a true success
October 29, 2009

Two years ago in my Nov. 4, 2007 The Ares-1 can't fly article and 15 months before in my Why the 5-segments SRB can't work article, I've clearly explained in full details and with plenty of evaluations and calculations, why the Ares-1 (the final version, NOT the 1-X) can't fly.

Apart the (possible) stability issues for a so tall rocket, in last 2 years I've always said (in my article and on several space forums and blogs) that "it [the Ares 1-X] WILL leave the launch pad, but ONLY because it will NOT have the 5th segment's "extra mass" and has a lighter dummy upperstage", so, the successful 1-X test ISN'T a surprise for me.

So, the (only apparent) "successful" launch of the Ares 1-X, last wednesday, DOESN'T "contradict" my articles and statements, but, unfortunately for NASA and the american taxpayers (that have paid several billion$ in last four years for the Constellation's R&D) the early data about the 1-X test, CONFIRM that an SRB5 based Ares-1 NEVER can fly (or, surely, NOT with an Orion atop it).

Despite the problems with one of the first stage parachutes that caused a damage to it at the splashdown (probably to the, less strong, dumb 5th segment) and the not perfect stage separation (a staging issue probably due to the unsolved SRB vibrations and/or the “burping” effect) the 1-X test has demonstrated that, a so tall rocket, can be launched without any (or, maybe, already solved by the Ares' engineers) steering and roll issue (that was a NASA concern in a 2006 press release) and that (maybe, due to a low wind speed the day of launch) also the liftoff-drift issue has proven unexisting (despite it has been launched from the SRB support much closer to the launch tower).

However, the ($445 million) Ares 1-X test has been very useful (that's why I've always suggested, in this article and on several forums and blog, to anyhow accomplish the 1-X test, no matter what is the Ares-1 future) not only for the data and info gathered by its 700 sensors (that we are waiting to know) but, mainly, because, the 1-X specs and the launch data, we already know (the upperstage mass and the max altitude reached) allow us to extrapolate these data to evaluate "how much mass" the real Ares-1 could lift and, ultimately, if the Ares-1 can fly, then carry a very heavy Orion to LEO.

As written two years ago in the early text of my Ares-1 article (and without any known data about an SRB launched alone, since never happened before last wednesday) I've evaluated that "a single (3.3 Mlbs. peak thrust) standard 4-segments SRB can lift a 240 mT upperstages' mass to 45 km. of altitude, at 3G" and (curiously...) the upperstage mass ("dumb" 5th segment simulator, forward skirt, forward skirt extension, frustum, the upper stage simulator and the crew module, with associated Launch Abort System, mass simulators) used by NASA in the 1-X test, has been exactly: 1,800,000 lbs. liftoff weight less 1,300,000 lbs. of the standard 4-segments SRB = 500,000 lbs. (or 227 tons) that's pretty close to the (240 tons) upperstage mass suggested two years ago in my article, while, also the max acceleration of the 1-X, has been close to what I predicted (3G).

But, unfortunately (for NASA and its Ares-1) I was too optimist in my evaluation of the max upperstage mass that a standard SRB can lift to 45 km. (the same altitude where the Shuttle's SRBs are jettisoned) since, the 1-X test has clearly revealed (as reported in this article) that (in its 123 seconds burning time) a standard SRB can lift 227 tons of mass to only 21.92 miles (35 km.) of altitude (at 3G) or only an (extrapolated) 176.5 tons to 45 km. (at 3.85G) or only an (extrapolated) 144.5 tons to 55 km. (that is the altitude where the Ares-1 first stage ends burn, and will be jettisoned) at 4.7G (probably too much for the astronauts, also excluding the expected 1st stage "vibrations" issue).

This (relatively) "weak" result is probably due to the fact, that, an SRB releases its max power only in the early 80 seconds of the flight, while, in the last 43 seconds the SRB's thrust falls very quickly, with the SRB's (very heavy) 87 tons dry mass that (clearly) remains unchanged and limits very much the rocket's performance.

Of course, the final Ares-1 first stage, in 2017 or later, will not use the standard SRB but the enhanced 5-segments SRB version, that, according to the (September 10, 2009) first ground test of the new ATK motor could add a +7% of peak thrust (3.6 million lbs.) vs. the (3.3 million lbs. peak thrust) old SRB (a thrust figure that's pretty close to a past 4+1 SRB test accomplished by ATK in 2003) so, by comparison the new SRB5 should lift up to 155 tons of upperstages mass to 55 km. of altitude.

Unfortunately, the SRB5 doesn't add only a +7% of thust, but, also a + 24% of liftoff weight, for a total mass (according to one of latest NASA Ares-1 overview) of 733 tons (including the frustum) or 143 tons MORE than the (590 tons) mass of a standard SRB.

So, the question, about the Ares-1 first stage, is: "who must lift this extra liftoff mass?"

Clearly, about 42 tons of this extra mass will be launched thanks to the +7% of extra thrust of the SRB5, but, the (residual) 101 tons of (propellant + segment) extra mass, must be subtracted from the max upperstage mass of about 155 tons that an SRB5 can lift to 55 km. of altitude leaving only 54 tons for the 2nd stage, interstages, Orion, Service Module, fairing and LAS mass.

And, since the (residual) "54 tons" total mass (clearly) ISN'T enough for the job, the ($35 billion R&D price) 5-segments SRB Ares-1 can't fly.

 



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