Saturday, July 31, 2004
Thursday, July 29, 2004
Wednesday, July 28, 2004
Tuesday, July 27, 2004
Monday, July 26, 2004
Wednesday, July 21, 2004
Tuesday, July 20, 2004
Monday, July 19, 2004
Friday, July 16, 2004
I have a booklet that is still available from The Kentish Knock Company and from ABE Books. The title is The Battlecruisers Essex and Sussex, Hypothetical Ship Designs from 1971. This booklet provides more information about my design methods, although it is now three years old. The basics are still a valid description of how I proceed. I have refined my process for computing power vs. speed, however, in that I make more use of an Excel spreadsheet.
My meager amount of knowledge of this subject, compared to someone like David Manley or David K. Brown, originated with the published works of William Hovgaard. He started his career as a Danish naval constructor, and finished his career as a professor at MIT. He had become an advisor to the U.S. Navy by the time of World War I.
William Hovgaard had three important books, in his series about warship design. The first that I had encountered was The Modern History of Warships (1920). The second was The General Design of Warships (1920). I had first seen these books at the University of Michigan, in the mid-t0-late 1960's. I never had expected to find the latter book, but the first had been reprinted, so I expected that I would eventually own a copy. To my surprise, in the fall of 2001, I was able to purchase a very fine copy, after I had bought a photocopy from the Library of Congress.
The third book was perhaps more influential, and went to multiple editions. It was The Structural Design of Warships. Given that I have not done the detailed design for a warship, this is the volume with which I have the least experience.
I have since supplemented my knowledge by study of D.K. Brown's books and the other books that do analysis of warship designs. At my level of understanding, we are reduced to needing to essentially interpolate from existing designs. What I have found really helpful are the published lists of weights for various battleships and battlecruises (primarily British). Perhaps I just need to expand my library, but there is much less information available about cruisers and destroyers weights distribution. For destroyers, I rely on Marsh's classic book, British Destroyers. It is good, but not as good as it would be if there were detailed weights for all the ships.
Thursday, July 15, 2004
I finally was motivated to do quick freehand drawings, on quadrille paper of the 29,000 ton battlecruiser and battleship designs. As I looked at the battlecruiser, I saw the hand of my friend Cliff, as he was quick to discard a conning tower, while I am a traditionalist, and tend to include at least a forward conning tower, if not an after "torpedo" conning tower, as well.
The top drawing is the fast battlecruiser, while the lower drawing is the battelship (my quick pencil sketches, done freehand).
The fast battleship that was intended to be built in parallel to the very fast battlecruiser was also 29,000 tons. The intended armament was 6-13.5in/45 guns. The idea was to restrict numbers of guns, so as to be able to carry less weight and devote more weight to armor and power.
The normal displacement was 29,000 tons, with dimensions: 620ft x 95ft x 30.2ft mean draft. The Cp was 0.59 and the Cm was 0.97 (Cp = prismatic coefficient and Cm = midship coefficient).
The weights would be allocated as follows:
Machinery 2,900 tons
protection 10,496 tons
Hull 12,180 tons
Armament 1,104 tons
Miscellaneous 2,320 tons
The ship looked like a Queen Elizabeth class battleship, as built, except with two turrets forward and one aft. There was still to be a conning tower and a tripod mast forward. The mainmast was a post, with a derrick for handling boats.
Wednesday, July 14, 2004
In one of my periods of wishful thinking about what was possible for powering ships, I conceived of a 38-knot light battlecruiser. The designed displacement was 29,000 tons and the armament was 4-13.5in/45 guns. The powerplant would generate 180,000 SHP. The speed-length ratio (V/sqrt(L)) was 1.3034. The dimensions were 850ft x 95ft x some draft. Let us assume a Cp=0.54 and a Cm=0.92. That would mean that the mean draft was 25.3ft. Two years later, I estimated it would take 209,235 SHP to reach 38 knots. Right now, I would not believe that 38 knots would be reachable under any circumstances.
The look of the ship was not that dissimular to the Courageous, except that the bow was raked. I gave her two funnels, with the fore funnel raised. There was no conning tower. The bridgework just rose at the start of the deckhouse. There was a tripod mast with a lower director top and then the main top centered on the mast. There was a light pole topmast with yards. There was also a mainmast that was sufficent to have a derrick. There was the usual distinctive top, with the triangular web pieces and then the pole topmast with a yard. The forecastle was very long, with a step foreward of the after turret. I didn't include any secondary armament, but there should have been at least some 4in guns for anti-torpedo work.
I had the mistaken idea, thirty years ago, that you could extrapolate a speed-length curve, based on SHP/ton of displacement. The problem is that "kind of works" for the residuary resistent (wavemaking), but it ignores the frictional resistence.
Frank Fox had seen my fantasy ship that had hoped to reach 45 knots, and gently demonstrated that it couldn't be done. The fastest that was feasible was about 33 knots (as I recall). The problem was that the length was too short (770ft). If you want speed, you must have length with enough displacement to carry a large power plant.
Tuesday, July 13, 2004
I was just rereading what D.K. Brown says about torpedo gunboats. By the early 1890's the Navy thought that they were too slow, and they turned to the early torpedo boat destroyers. D.K. Brown says, though, that in any sort of a seaway, the TGB's could outrun the early destroyers, which had too little freeboard. This was not corrected until the River class boats, which had a lower speed and a raised forecastle.
D.K. Brown says that the TGB's could have formed the basis for building, rather than the enlarged torpedo boat, which was in fact used. He says that they were better ships than they were given credit for at the time.
Saturday, July 10, 2004
I will be scanning and writing about a group of ship designs that I did up to the spring of 2001. I have long had a design pattern for battlecruisers and fast battleships during the period of 1905 to 1914. Most or all of these designs have three round funnels, with a forward tripod mast with a top and director. I have liked the sort of tiered bridge structure with a pilot house that protrudes forward, as the highest level. Good examples of real ships that these are similar to are the Barham (8-15in) and Tiger (8-13.5in).
Friday, July 09, 2004
Looking at my drawing, I realized that Colonel Cuniberti's battleship design looked more like an armored cruiser than a battleship. Perhaps it was the four funnels or it might have been the 24 knot speed. The gun layout also resembles a pre-dreadnought armored cruiser, with the wing turrets, with single and twin guns.
I probably need to play with the parameters, to see if I can make some compromises to make my rendering of the design closer to what Colomel Cuniberti intended. I would like to have thicker belt and barbette armor, in particular, while maintaining a good speed. I need to break out my copy of D.K. Brown's book, Warrior to Dreadnought, to get some additional data that might be of help.
Wednesday, July 07, 2004
I thought it would be good to illustrate the sort of drawing I do as an aid to doing the general design of a warship. I generally do the drawing on quadrille paper. If I wanted to do a cleaner drawing, I would print it and trace on the back, with ink. I would then rescan that traced drawing.
Sketch of Colonel Cuniberti's battleship design.
I just tried to see what I could do with Colonel Cuniberti's battleship proposal from 1903. I must admit that D.K. Brown is correct that "it can't be done", as originally proposed. I have made some compromises to see how close I could come to the original design, and I have made the result available for download. This are only the weight calculations. I have not attempted the power calculations. The lowest displacement I could get was 18,014 tons normal. That is with very lightweight construction for the hull, pared down protection, and cruiser-style machinery. My designed SHP is 37,500 tons.
I found that I had a Word document, from three years ago, that sort of explains my methods for doing a general design. The example is rather extreme, a large battlecruiser with 20-inch guns. Actually, the displacement is rather light for the size of the ship, but this is the most accessible example that I have. I will make other documents available for download, over time.
Obviously (I would think), a trained naval architect who is also a naval history enthusiast, such as David Manley, could probably do a better job of doing a general design. I suspect that the sort of data that is really needed to do a good job might not exist. I have some hope that "ship's covers" might be obtained that would provide much of what is needed to analyze classic Dreadnought designs, so that we might be able to do a better job in our design work. The "Anatomy of a Ship" books would seem to be another good source of data.
I don't know if anyone else has been interested in designing their own 1905-1927 era warships, but I have been interested in doing that for a very long time. All that is really needed is to do the general design. That involves doing a layout, weights analysis, and power calculations. The last is the most time consuming of the design process (at least the way I do it). I am just going to outline the process, for this post.
The weights analysis can be done, with some work, using an Excel spreadsheet. I have been using an Excel spreadsheet for the power calculations as well. I mechanized a process for doing the calculations that I learned from Frank Fox (he is interested in more than just 17th Century ships).
I use the weights spreadsheet to do the displacement calculations, as well, so that I define the fundamental dimensions there. Then, I do a scale drawing. I have found that a 1-inch = 100 feet drawing is adequate. For greater accuracy, you can always do a larger scale drawing, but there are so many approximations involved, that I only do a larger scale drawing for smaller vessels.
I actually clone an existing spreadsheet, to start the process. However, the basic outline is that I have the dimensions and summary weights on the left. On the lower right, I do the hull armor calculations. On the upper right, I do the turret and gun weight calculations.
To do decent estimates of turret and gun shield weights, you need to do some larger scale drawings that you can measure. It is also helpful to refer to real ship data for which there are weight noted. I have use both R.A. Burt's book, British Battleships of World War One and John Roberts' Battlecruisers book. The book that got me started on doing general design was William Hovgaard's classic book, The General Design of Warships. I was amazed that I was actually able to buy a copy at a reasonable price. Another source is paying some fairly big bucks to get the Library of Congress to make a good photocopy for you. I did that first, before I knew that the book might be available.
The propulsion calculations require determining the wave-making resistance and the surface friction resistance. There are more modern methods available that seem to depend on interpolating from a database of ship characteristics. The classic method uses graphs from Speed and Power of Ships and Schoenherr coefficients from Morton Gertler's A Reanalysis of the Original Test Data For the Taylor Standard Series. This book occasionally comes on the market. I found a copy a few days after Frank Fox had recommended the book to me. Explaining the method will have to wait for later, as it is quite involved. Essentially, for a range of speeds, the residual resistance and frictional resistance are calculated and summed. From this "effective horsepower", then we can estimate the actual horsepower needed, given some assumed efficiency. I have some example spreadsheets that illustrate the method (sadly, I lost a lot of this sort of work in October 2002 when I had a hard disk failure that wasn't adequately backed up).
Tuesday, July 06, 2004
Several years ago, I had some communication with David K. Brown, the retired naval constructor and author. My understanding is that he thinks that battlecruises with light side armor are acceptable (with "splinter protection") if the "vitals" are sufficiently protected. That is really the modern protection design pattern. I think that he would prefer at least 6inch side armor, if it could be had, for a battle cruiser. What really needs to be protected are the magazines. I would add that something besides Cordite should be used as your gun propellant, as well. Nitrocellulose would seem to be a good candidate. Cordite is BAD, and should be avoided at all costs. Four British battlecruisers, as well as other ships, were lost due to the use of Cordite. The problem was not the lack of armor, but the unstable propellant in use. As Admiral Fisher would say "armor is vision", so more armor is not that bad, if you can provide a good speed and a heavy armament. Ships like the Derfflinger were good, but needed something larger than 12inch guns.
Sunday, July 04, 2004
Actually, they were called "Jane's All the World's Fighting Ships", but let's not be picky. I have the 1898 reprint and a REAL (former Brooklyn Navy Yard copy) 1903 volume. I was positioning myself to get 1899 and 1904 copies, when all that got swept away by the "economic downturn". I had seen the 1904 volume in 1966, but the University of Michigan library did not take care of it. It essentially ended up as dust (they didn't take care of the acid paper problem).
I just unpacked the box that had my copy of All the World's Fighting Ships 1903. Of course, I wanted to be able to write about the article by Colonel Cuniberti. His "ideal battleship" has a raised forecastle, with a ram forefoot and a "cruiser spoon" stern. The rudder is balanced, and the deadwood is cutaway, quite radically. The bottom slopes up to the forefoot from the first funnel (the Moltke and Göben were like that. There are two pole masts and four funnels. There are conning towers, fore and aft, with a minimal amount of bridgework around them. The guns are arranged in lozenge fashion. On the raised forecastle is a twin 12inch turret. On the quarterdeck is another. At the forecastle deck level, there are twin 12inch turrets at the deck edge, on either side. They align between the second and third funnels. There are four single 12inch gun turrets. They are at the quarterdeck level and form a square. They are forward and aft of the amidships turrets. There is no "secondary armament", just an anti-torpedo battery of 12-12pounders and 6-"pom-poms" that can be dismounted.
The belt is complete. The thickness is 12-inches, at the waterline. The six amidships turrets are protected by a raised citidal that is 12-inches thick. Forward of the citidal, there is 6-inch armor to the bow.
Colonel Cuniberti's dimensions were:
Length: 521-1/2 feet
Beam: 82 feet
Mean draft: 27-1/2 feet
I have come around to the view that if the form and parameters are only moderately outrageous, it might be possible to have a ship that comes close to these parameters. I suspect that fuel capacity would be small, the hull would be rather light weight, and the machinery to a lighter weight than would be typical in British pre-dreadnought battleships. I did a spreadsheet to try the design, and I must admit it could be done, although it would be pretty radical.
Saturday, July 03, 2004
Anyone who is interested in German warships during the period 1905-1918 needs to read Deutsche Grosskamschiffe 1915-1918. What I was interested in is the information about planned ships that were never built, and the evolution of ideas, during the war. The last drawings in the book look a lot like the panzerschiffe Deutschland/Lützow, built postwar. There may be something better, than this book, but this is the work that I know on this subject.
Thursday, July 01, 2004
Ever since I saw the photograph of the torpedo boat destroyer Viper making 36 knots on trials, I was attracted to the picture. The Viper is shown squatting at the stern, with the forefoot out of the water. It is amazing to me. It really was a hotrod, as built. It had direct drive turbines, and too much power for the size of the hull. I was inspired to paint the picture, and it can be seen at HMS Viper painting.