“This is the dam control room…”
posted by robert - December 22nd, 2004 at 8:34 AMSaw an article in passing on CNN.com this morning, about Boeing launching a prototype of one of their new Delta 4 Heavy booster assemblies. Nothing really spectacular about it — still old-school rocket technology, etc. etc. — except for this bit:
The successful launch was a critical milestone for the Delta 4 Heavy, which features three of the company’s common core boosters joined side-by-side. Fired simultaneously, each of the three hydrogen-powered Rocketdyne-built RS-68 main engines generates 17 million horsepower, about the equivalent of 11 Hoover Dams.
It’s that last line that gets me. How exactly does Hoover Dam generate something that is best described in dam horsepower? As a reasonably sharp tack, I deduce that the authors of this article (or, really, the CNN.com science desk staff) must be talking about some slightly muddled metric regarding the dam turbine output capacity. Then again, it’s possible that there’s some obscure tie-in to the dam water flow rate. I’m not entirely sure. And even if the dam horsepower angle is technically correct, surely there is a better way to compare these things. Joe America is going to read this article and try and figure out how exactly the comparison is meaningful to him …other than somehow giving the impression that 3 Delta class boosters strapped together and fired simultaneously pack quite a dam wollop.
December 30th, 2004 at 1:36:18 pm
With respect to 11 Hoover Dam equivalents, the discoverer of the above statistic probably means ‘equivalent of Hoover Dam electrical power output in Watts’ noting 1 hp equals 745.69987158227022 W.
That being said, I’m not entirely certain why anyone would care to know the power output of a throttlable liquid fuel rocket engine; it roughly corresponds to propellant mass flow rate times enthalpy of reaction times some obscure coefficient expressing efficiency of the engine and says little about its fitness as a first-stage rocket engine lifting off from sea level.
Surely maximum thrust in a vacuum would sufficiently astonish the average onlooker. Moreover, if one wished to convey the awesome lift potential of the Delta IV Heavy, perhaps they’d mention the maximum payload the rocket could insert into geosynchronous orbit.
This mass could be expressed in kegs of Sam Adams if need be.