Technical Information for Active Duty IUSS Analysts, and for Former System Analysts Still Interested
By Bruce Rule - Aug 26, 2014
This document, discussions of submarine pressure-hull collapse events and numerous other subjects have been posted on this site to protect this information from what otherwise would be almost inevitable loss. Such archiving hopefully with provide these assessments to the active-duty “System” personnel for application to analyses of future acoustic events.
The primary reasons the SCORPION Court of Inquiry (COI) got 14 of the 17 conclusions they drew from analysis of acoustic detections of the SCORPION events WRONG in 1968/69 was their failure to examine System detections of the THRESHER loss event in 1963, and to research the dynamics and energy-release levels of implosions of large structures that occur at great depth. All should learn from the COI's mistakes.
1. Vanishing Point Analysis (VPA) (Google Vanishing Point Detection for Architectural Photogrammary) of the LADA Class submarine image shown by http://img461.imageshack.us/my.php?image=shaft0zo.jpg indicates the 7-bladed, skewed propeller turns within a circle that is 29-percent (plus/minus two percent) of the total width of the stern-planes at the projected point of intercept. If the LADA stern planes have the same span as the AMUR 1650 Class submarine (export version of the LADA)(36.5 feet or 11.1m), the diameter of the right-hand turning (stern view) LADA propeller is 10.6 feet (3.2m) plus/minus four percent. COMMENTS: this would appear to be a photo-interpreter's (PI's) technique; however, it has been the writer's experience that at least some PI's are not aware of – or do not apply – this very useful approach to image analysis which can provide otherwise unrecoverable information for acoustic-based engineering assessments that have often been confirmed to have been as important as the primary objective of such analyses. 9This is yet another example of the value of doing analyses that relate to acoustics, i.e., don't rely on others; know how to do a VPA, and do it yourself. Note: picking the vanishing point is not easy; when asked to do so in a high value case, several PI's got it wrong. It is a skill not dissimilar to reading a gram.)
2. The relationships between the horsepower (hp) rating of tbe Kolomna D42 diesel engines and dc generator driven by those engines is 0.78. That relationship is based on known values for the 1720 hp 1DL42 engine and the 1000 kW PG-142 generator, both late-1950s technology still employed by early Project 877 KILOs. Some (later) Project 877 KILO Class units have two 4DL-42M diesel engines, each rated at 2,000 horsepower. This power rating could be the upper limit possible with single-stage turbo-charging. The use of two-stage turbo-charging with air-cooling after each stage to achieve Mean Effective Pressures (MEPs) in excess of 2.0 (290 psi) could enable non-reversing, in-line, 6-cylinder Kolomna D42 (ChN30/38) series engines to develop more than 2,000 horsepower at 750 rpm.
3. www.kolomnadiesel.com/eng3/ed2_osob.shtml states that the Power Factor for the Kolomna D49 ED2 diesel-generator, a candidate engine for the cancelled/suspended LADA/AMUR Class submarine, was increased to 0.80; hence, this confirmed value can be used with the published hp ratings of current production Kolomna diesel engines to reliably determine the kW ratings of associated generators, or vice-versa. In the case of the V8 ED2, an engine hp rating of 1750 at 1000 rpm converts to an engine-driven generator rating of 1045 kW. (1750 hp times 0.80 divided by 1.34 equals 1045 kW) The D49 ED2 directly drives a 6-pole generator to produce 50 Hz ac power which can then be converted to dc power for submarine propulsion. This constant-speed diesel driving an ac generator is the approach now taken by designers of advanced diesel submarine propulsion systems.
4. The footprint (required deck area) of the 1750 hp V8 D49 (ChN 26/26) ED2 engine plus the generator intended for use in the LADA/AMUR 1650 is about 50 square feet (4.6sgm). This compares with a footprint of 90 square feet (8.4sgm) for a 1720 hp 1DL42 (ChN 30/38) engine plus generator system which is similar to the diesel-generator used in Project 877 KILO Class submarines. The use of a 1,000 rpm V8 diesel-(ac) generator in LADA/AMUR hulls instead of an in-line, 6-cylinder 700 rpm diesel-(dc) generator reduced the required deck area by nearly half and increased available electrical power by about five percent. The displacement of the V8 D49 engine with bore and stroke of 260mm is 31.5 percent less than the displacement of an in-line, 6-cylinder D42 engine with a bore of 300mm and a stroke of 380mm. Even if the LADA/AMUR 1650 never enters series production, the size and power characteristics of the V8 D49 suggest it could be used in future Russian diesel submarine designs.
5. Since 1978, the Special Boiler-Building Design Office has been the leading Soviet/Russian developer of propulsive systems with Electro-Chemical Generators (ECGs). It drew on the experience of the Urals electrochemical works and NPO Energia who developed ECGs for spacecraft. In that way, a Kristall-20 engine for submarines made its appearance, using oxygen and hydrogen. The latter is present in bound form: an intermetallic compound. Second-generation Kristall-27 and Kristall-273 engines can now be installed on new diesel-electric submarines, increasing their endurance to 45 days. Without divulging all secrets of Russian shipbuilding, we may say that the endurance of Sankt Peterburg (LADA Class) is exactly 45 days. Comment: This may be the new submarine engine Viet Nam is waiting for. (See earlier post that subject)
6. To commutate effectively, an armature slot pitch (the span of the slot plus the tooth) of a dc motor should not be less than one inch (2,54cm) and no more than 1.25 inches (3.18cm). Using a measured diameter of 6.4 feet (1.95m) for the outer casing of the PG-141, the probable diameter of the armature should be about four feet (1.2m). These values suggest the number of slots in the PG-141 dc motor armature should be within a range of 120 to 150. The PG-141 – or variants thereof – were used by JULIETT, BRAVO and INDIA Class submarines, and are now being used by Project 877 and 636 KILOs and by the Project 955 BOREY SSBN.
7. Because of the advantages of using a diesel-generator system with a line-frequency significantly greater than 50 Hz (makes possible the use of smaller and lighter dependent motor-driven systems that can operate at very high speeds), the feasibility of using a D49 engine operating at 1,000 rpm to drive a 48-pole generator to produce 400 Hz power was investigated with the following results: To insure the physical integrity of the generator rotor, its peripheral speed should not exceed 12,000 to 13,000 feet-per-second; hence, the rotor diameter should be no greater than about 50 inches (1.27m). This dimension requires a 3.25 inch (8.3cm) span for each field pole and a span of 1-1.5 inches (2.54-3.8cm) for the stator slots. With these span dimensions, each time a field-pole passes one slot and moves to another, there will be a significant variation in the magnetic flux which often produces what is called tooth-ripple in the generated voltage, i.e., voltage with a high harmonic content which can cause heating (and noise) problems in dependent motor-driven systems. Unless these problems can be overcome for relatively high kW power systems such as the D49, it appears unlikely Russian diesel submarines currently in production will use 400 Hz as the primary ac line frequency as was the case with the ALFA Class Soviet SSN. To also take advantage of the size reduction provided by higher speed of the driving turbine – as will the OHIO REPLACEMENT US SSBN (by using two high-speed turbo-generators) – two configurations are suggested for Soviet/Russian nuclear submarine 400 Hz power systems: (1) 6000 rpm turbines driving 8-pole generators or (2), for smaller systems, 12,000 rpm turbines driving 4-pole generators. COMMENTS: (1) An early US nuclear submarine twin-bus SSTG design employed turbines operating at 7320 rpm to drive 6-pole generators (through a reduction gears at 1200 rpm to produce 60 Hz power, and (2), German diesel submarines, U212 and U214, use MTU 16V T8396 diesel engines that operate at a constant speed of 1,800 to drive four-pole ac generators to produce 60 Hz power. The ac output of these RWE Piller GmBH 750 kW generators is rectified for use by dc power consumers. AC-to-dc power systems have significant size, weight and safety advantages over traditional dc-only systems.
8. The purchase of THE FIVE COLORS OF TIME by I. D. Spassky, Chief Designer at RUBIN, is suggested. Circa 10 years ago, the book assigned a color to each of the eras of Soviet submarine construction with the most recent era – about about 10 years ago – being assigned the color grey, for obvious reasons. In chronological sequence, the periods are: white, red, blue, golden and grey. An earlier Spassky book is available through Amazon.com. In that 2001 book, Spassky noted that future diesel-electric propulsion systems will employ highly efficient propulsion motors with excitation systems using permanent magnets.î The use of propulsion motors with permanent magnets in LADA/AMUR Class submarines is confirmed by www.ckb-rubin.ru/eng/project/submarine/noatomp/index.htm As previously reported, www.kolomnadiesel.com/eng3/d49.shtml states: PERMASYN was determined to be the propulsion motor of choice for the latest generation of submarines class 212 of the German and Italian Navy. PERMASYN motors are advanced synchronous motors with permanent-field excitation specifically designed for submarines. Spassky also notes that the reserve propulsion capabilities of then future generations of nuclear submarines would be foldable or retractable columns or other designs (BOREY) that do not disturb the streamline shape of the hull (VICTOR, ALFA), and during the design of main propulsors, water-jet propulsors would find a wider application (BOREY). COMMENTS: (1) Spassky obviously knew whereof he wrote, and (2), this is yet another example of the value of reviewing foreign technical literature that discusses submarine systems. Such literature – as in this case – often provides a preview of “coming attractions.” (3) Over almost 50 years, the writer has observed what could be called an “entrenched myopic mentality” that denigrated the potential value of open source information, i.e., why bother with unclassified information when you have classified data. It is time to abandon that concept.