The Trials
Upon completion, the trials were with the new ship on the program.
On 4 June 1940 graduated from the America the builders trials successfully.
On June 9, the liner started from Newport News to the north, in the direction of Rockland off the coast of Maine in order to complete a further series of tests on the Measured mile course in the U.S. Navy. Maritime Comission, builders, owners who were Navy many demands from all sides meet.
To ensure optimal conditions, a stop in Boston was inserted where the hull was cleaned and painted in a dry dock.
Aerial view during builders trials off Virginia Capes.
-Picture: United States Lines-
On 13 and 14 June 1940 then was the moment of truth. America would be all ambitious demands?
The extensive testing required the future transatlantic liner from everything. Maneuverability and speed were determined on a fixed price at a specified distance, tested the brakes at a free fall anchor of the anchor, the helm was tested for function at high speed and sharp turning maneuvers, simulating an emergency stop from full speed.
Following these tests followed an eight-hour endurance test for machines.
The results were in almost all areas more than satisfactory and exceeded the requirements. Excellent maneuverability, acceleration recorded from the water of the new ship. The America briefly reached a top speed of 25.3 knots at a power of 42850 hp and an average maximum speed of 24.5 knots over a longer period.
America in Boston drydock for underwater hull painting and cleaning.
-Pictures: National Archives-
Because of the past at the same time fuel consumption below expectations, paid the Maritime Comission of the builders yard of the maximum bonus that was advertised for less than the consumption.

There were also discrepancies in the results of the planning, such as soot and heavy oil residues satisfactorily keep the bold design of the chimneys, which proved to be suitable as insufficient by the upper aft deck.
A solution had to be found quickly and so it was decided the problem in the easiest way to solve and reduce deposits on the deck by simply increasing the chimneys. Whole 5 meters higher towered the two chimneys of the extension in the sky, which did not change the design of the ship insignificant.
Above: Cachet of first trip of S.S. America from Newport News to Boston.
-Picture: courtesy of Bill Lee-





Left: Naval Trial Couse at Rockland Harbour, Maine and its "measured mile course".
America during a sharp left turn on a rudder test (note the list to starboard).
-Picture: National Archives/ US-Lines-
Anchor chains are cooled with water after a successful test of the anchor windlass brakes stopping the anchor from free fall.
-Picture: National Archives-
Heavy fog during the trials. A crew member rings the ships bell..
-Picture: National Archives-
Back to overview page -->
America with low funnels in James River.
-Picture: United States Lines-
America during speed trials on a straight track after a rudder test, as the course of the wash in the distance suggests.
-Picture: National Archives/US-Lines-
Left: The ratio of needed power in relation to achieved speed of America extrapolated from model tests in 1940.
Particularly important here are the curves of the R.P.M. (rounds per minute of the propeller) and the S.H.P. (shaft horse power, the actual transmitted horsepower to the shafts).

You can see that the required horsepower for increasing speed climbs exponentially while the revolutions per minute of the propellers climbs linearly. So with increasing speed, the ratio between added speed and  needed horsepower and therefore the fuel consumption is becomming more and more inefficient.
To achieve a speed of 22 knots  America needs about 28,000 hp. But to achieve a speed just 3 knots higher (25 knots), the required power is doubled to56,000 hp.
To find an economical medium between speed and needed power, the cruising speed of 22.5 knots of America is at the point at which the curve of horsepower, and the curve of revolutions of the propellers per minute cut (red circle).
-----------------------------
This chart refers only to model tests and theoretical extrapolations BEFORE the trials. After the trials, there was a slightly more efficient power to- speed ratio of the real ship. For a general idea of the performance curves of America this diagram still is  a useful overview.
advertisement:
© 2012-2013 ssamerica.bplaced.net | Impressum | Contact | Site Map | technical problems
advertisement:
German version:
Please Note: Text on this page is only electronically translated.
This will be replaced by a better translation as time allows.