The Hellenic Navy (HN) (Greek: Πολεμικό Ναυτικό, Polemikó Naftikó, abbreviated ΠΝ) is the naval force of Greece, part of the Greek Armed Forces. The modern Greek navy has its roots in the naval forces of various Aegean Islands, which fought in the Greek War of Independence. During the periods of monarchy (1833–1924 and 1936–1973) it was known as the Royal Navy (Βασιλικόν Ναυτικόν, Vasilikón Naftikón, abbreviated ΒΝ).The total displacement of all the navy's vessels is approximately 150,000 tons.The motto of the Hellenic Navy is "Μέγα το της Θαλάσσης Κράτος" from Thucydides' account of Pericles' oration on the eve of the Peloponnesian War. This has been roughly translated as "Great is the country that controls the sea". The Hellenic Navy's emblem consists of an anchor in front of a crossed Christian cross and trident, with the cross symbolizing Greek Orthodoxy, and the trident symbolizing Poseidon, the god of the sea in Greek mythology. Pericles' words are written across the top of the emblem. "The navy, as it represents a necessary weapon for Greece, should only be created for war and aim to victory."...............The Hellenic Merchant Marine refers to the Merchant Marine of Greece, engaged in commerce and transportation of goods and services universally. It consists of the merchant vessels owned by Greek civilians, flying either the Greek flag or a flag of convenience. Greece is a maritime nation by tradition, as shipping is arguably the oldest form of occupation of the Greeks and a key element of Greek economic activity since the ancient times. Nowadays, Greece has the largest merchant fleet in the world, which is the second largest contributor to the national economy after tourism and forms the backbone of world shipping. The Greek fleet flies a variety of flags, however some Greek shipowners gradually return to Greece following the changes to the legislative framework governing their operations and the improvement of infrastructure.Blogger Tips and Tricks
This is a bilingual blog in English and / or Greek and you can translate any post to any language by pressing on the appropriate flag....Note that there is provided below a scrolling text with the 30 recent posts...Αυτό είναι ένα δίγλωσσο blog στα Αγγλικά η/και στα Ελληνικά και μπορείτε να μεταφράσετε οποιοδήποτε ποστ σε οποιαδήποτε γλώσσα κάνοντας κλικ στη σχετική σημαία. Σημειωτέον ότι παρακάτω παρέχεται και ένα κινούμενο κείμενο με τα 30 πρόσφατα ποστς....This is a bilingual blog in English and / or Greek and you can translate any post to any language by pressing on the appropriate flag....Note that there is provided below a scrolling text with the 30 recent posts...Αυτό είναι ένα δίγλωσσο blog στα Αγγλικά η/και στα Ελληνικά και μπορείτε να μεταφράσετε οποιοδήποτε ποστ σε οποιαδήποτε γλώσσα κάνοντας κλικ στη σχετική σημαία. Σημειωτέον ότι παρακάτω παρέχεται και ένα κινούμενο κείμενο με τα 30 πρόσφατα ποστς.........

Monday, April 7, 2014

Acoustic testing at NASA...[ 3952 ]


Space Launch System Core Stage Model 'Sounds' Off for Testing

A 5-percent scale model of the Space Launch System (SLS) core stage fires up for another round of acoustic testing at NASA's Marshall Space Flight Center in Huntsville, Ala.


A 5-percent scale model of the Space Launch System (SLS) core stage fires up for another round of acoustic testing at NASA's Marshall Space Flight Center in Huntsville, Ala. SLS, NASA's new rocket, will be the largest, most powerful rocket ever built for deep space missions. 
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The SLS core stage, towering more than 200 feet tall with a diameter of 27.6 feet, will store cryogenic liquid hydrogen and liquid oxygen that will feed the vehicle’s RS-25 engines.
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 The acoustic tests, which began in January, will show how powerful noise from the engines and boosters can impact the rocket and crew, especially at liftoff. Data from the tests will help verify the rocket's design and help develop an effective suppression system to stifle the sound. 
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The current test series, which began March 20, will be used to determine the noise reduction capabilities of the water suppression system at NASA's Stennis Space Center near Bay St. Louis, Miss.
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The system will be used for core stage "green run" testing. "Green run" testing ensures all stage and engine parts have been exposed to flight-like environments prior to use on a mission.
Image Credit: NASA/MSFC/David Olive

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