ISO 13643-5:2013 download.Ships and marine technology Manoeuvring of ships Part 5 Submarine specials.
This partol ISO 13643 defines symbols and terms and provides guidelines forthe conduct of tests to give evidence about the manoeuvring ability in the vertical plane of submarines and models. It is intended to be read in conjunction with ISO 13643-1.
2 NormatIve references
The following documents, In whole or In part, are normatively referenced In ISO 13643-5 and are Indispensable for Its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) apphes.
ISO 13643-1, Ships and marine technology — Manoeuvring of ships — Part 1: General concepts, quantities and rest conditions
3 Terms and definitions
For the purposes of ISO 13643-5, the following terms and definitions apply.
meander test
manoeuvring test to establish a submarine’s manoeuvnng characteristics and to verily the submarine’s dynamic stability in the vertical plane
3.2
vertical overshoot test
manoeuvrlng test to determine the effectiveness of the stern planes when initiating and terminating changes of depth
3.3
neutral level flight test
manoeuvring test to determine the trim angle and the hydroplane angles at which the submarine maintains a Constant dived depth at any given speed during submerged operation
Mote I to entry: Neutral level flight lx obtaIned
— for submarines with retracted bow planes by usinga definite trim angle and a definite angle of stern planes, and
— for submarines with non-retractable bow planes, by using definite angles of the bow and stern planes for arbitrary trim angles (preferably s s 09.
3.4
crItical speed test
manoeuvring test to determine the speed at which the effect of the hydroplanes Is reversed during submerged operation
5 General test conditions
In addition to the general test conditions outlined in ISO 13643-1, the following specific test conditions shall he complied with.
— During the test, including the approach phase, each successive position of the ship shall be recorded at suitable time intervals (usually every second).
— The submarine shall be trimmed according to the results of the neutral level flight test (see Clause 8).
— Dived depth and water depth shall be sufficient (a clearance of at least one boat’s length to the surtace and to the bottom shall be maintained). For model tests, surface and bottom effects shall be excluded by the use of suitable measures.
— The bow plane angle shall remain unaltered.
— There shall be no relocation of mass (e.g. due to movements of the crew) during the conduct of any test. Unavoidable shifts of mass are to be compensated and recorded.
6 Test 5.1 — Meander test
6.1 Description
A series of tests for different Initial speeds must be conducted since damping and time constants of the motion of the submarine are speed dependent, and a boat that proves to be stable at low speeds may become unstable at higher speeds.
For safety reasons, the series of tests shall be commenced with a low Initial speed. V0.
The submarine shall approach on a steady speed, V0. before commencing the test. During the test. the propulsion plant settings must remain unaltered and the heading kept as constant as possible. Heading and rudder movements shall be recorded throughout the test (Ideally, at Intervals of 1 s). If the submarine is equipped with planes acting simultaneously in the horizontal and the vertical directions
(e.g. X-planes), these planes should be controlled in such a way that a steady heading is maintained as a matter of priority.
After the submarine has been moving ahead for at least iwo minutes without signilicant movements of rudder and planes, the stern planes are set to the specified test stern plane angle, M. as last as possible and must be held there until the (rim angle has deviated from the initial trim angle, O, by the specified execute change of trim angle, jSO. At this point, the stern planes are reversed to the initial posItion and held until the test is completed.
The stern plane impetus moves the submarine from Its equilibrium condition. Test stern plane angle. and execute change of trim angle, shall be selected in such a way that the stern plane impetus acts as quickly and powerfully as possible, and the submarine has at least three measurable trim amplitudes, O In the case of a subsequent oscillation. Only data after completion of the simulation are to be evaluated,
Because of the stern plane Impetus, the submarine turns about Its transverse axis and. In doing so. changes its trim and dived depth in the direction in which the planes were acting. Submarines with high damping approach a different dived depth without oscillation about the transverse axis. If the damping is less, the submarine starts to oscillate about the transverse axis. As long as the oscillation is damped. the submarine is stable and approaches a different constant dived depth. On the other hand, if the trim amplitude, 0A. increases, the submarine is dynamically unstable. The mean dived depth may alter also.
If the submarine demonstrates pronounced Instability, the test Is to be stopped Immediately for safety reasons.
8 Test 5.3 — Neutral level flight test
8.1 DescriptIon
8.1.1 Modeltest(M)
Moments and forces are measured at the supporting structure and recorded for the submerged submarine model, preferably initially on even keel when at a standstill with the stabilizing fins and stern planes set to 6cj = I) and 5 = 0 (inItial condition). Now the submarine model is accelerated to a test speed Va at which the bottom and surface effects are still negligible. Then, the changes of the vertical force and the trim moment relative to the initial condition arc measured and recorded.
In successive test steps with other trims, the initial condition at standstill is to be determined again.
The angles of the stabilizing fins and the stern plane, as well as the trim angles or bow plane angles, have to be varied in suItable increments (for instance, trim angle increments oIO,5°, stabilizing fin/hydroplane angle increments of 1°). For stern planes with fixed post and movable part, It is recommended to set both to the same angle (ösx = 65). The angles have to be selected so as to provide positive and negative values for the quantities of the vertical force and the trim moment when one parameter is maintained (trim angle or hydroplane angle) so that the zero value may be interpolated for evaluation purposes.
The angle of the stabilizing fin and/cr fixed post of stern planes derived from the model tests according to .Z.1 servesas input forthe detailed design.Thetrim angle and/orhydropbneanglesatwhich thesubmarine is assumed to maintain a constant dived depth at all speeds should be ascertained by full-scale tests.
8.12 Full-scale test (S)
8.1.2.1 General
A submerged cruising condition is to be found at which not only the total force and the total moment but also the difference between weight and buoyancy and the static trim moment are zero At relatively high speeds, the difference between weight and buoyancy and the static trim moment have almost no influence on the dynamic behaviour of the boat Therefore, the neutral level flight condition can be determined comparatively simply by extrapolation.
8.1.22 Submarines with retractable bow planes
The submerged submarine is compensated at a speed of about twice the critical speed. VCR (see Clause91. by use of the trimming and compensating systems, so that depth keeping is possible with retracted bow planes at a stern plane angle between t 1.5° and a trim angle between -1° and 0°. The actual quantity and the centre of gravity of compensating water have to be measured and recorded.
After that, the submarine shall be kept on a constant dived depth by use of the stern planes. Approaches at test speeds, V1, of about 50 %. 60 %. 65 %. 75 %. and 90 % of the maximum speed are conducted successively. These test speeds. V01. are selected such that an almost even distribution of test stern plane angles. 65, and trim angles. O, is obtained when plotted as a function ofthe inverse squareofthe test speed. V0. The test speed. Vffi. the rebted stern plane angle, 65. and the resulting trim angle, 0s shall be recorded.
After evaluation as per U2.2.L the test speed is set again to about twice the critical speed, VCR. The submarine is trimmed and compensated until it finally maintains a constant depth with a stern plane angle, óso. and trim angle, Os. for neutral level flight determined by the evaluation. The quantity and the centre of gravity of compensating water shall be measured and recorded.
In order to verify the angles 8so and 8sj for neutral level flight, the submarine speed will be Increased in increments up to a speed. V01, of 75 % of the maximum speed without changing the setting of the stern planes. Dived depth and trim angle are to be measured and recorded at suitable time intervaLs. After that, the stern plane is used to maintain depth, ii necessary.