David Merriman’s 57″ Seaview part 9B
Back to part 9A
This SEAVIEW model, like other vehicles traveling near the surface, expends a significant form of energy overcoming ‘wave making’ drag; that phenomena where the elasticity of the liquid/gas interface point (waters surface, boy’s and girl’s) interacts with the vehicle, causing drag. This wave making effect all but diminishing to zero once the vehicle has descended to a point greater than three hull diameters below the surface.
As a practical matter, though, even depths as shallow as ‘periscope depth’, are enough to negate most of the wave making drag. By the way, on no r/c model submarine I have ever operated, nor the diesel boat and SSBN submarines I have served aboard, have I seen a more pronounced bow wave than that originating from the bow of the SEAVIEW when operating at speed on or near the surface. Lots of drag going on down there!
PRINCIPLES OF OPERATION OF A PRACTICAL SUBMARINE
A surfaced submarine can dive without changing its weight. It does so by forcing itself beneath the surface employing the horizontal planes and hull to produce an amount of dynamic ‘lift’ downwards to overcome the added buoyant force represented by those structures pulled beneath the waters surface. Such a maneuver generates a great deal of drag and requires maintenance of a considerable amount of thrust. This ‘dynamic diving’ type submarine must remain in motion, constantly fighting the upward buoyant force, else it would bob to the surface like a cork. Not very ‘scale-like’ in my opinion, and requires an inordinate amount of energy to stay submerged.
Most toy r/c submarines are dynamic divers.
Yes, there is inherent safety with this method: the submarine will usually surface the moment power is backed off. And, indeed, such models, through elimination of a ballast system and its attendant complexities, are simpler to construct and maintain; dynamic diving type r/c submarines are cheaper to purchase, easier to build, and require less maintenance than their static diving cousins.
However, ‘real’ r/c submarines assume ‘submerged trim’ by employing a means of taking on water to increase the weight of the submarine. The weight of that ballast water equal to the buoyant force represented by those structures of the submarine that are above the water in surface trim. This type submarine is described as a ‘static diving submarine’ – no dynamic force is required to keep this type boat submerged. When the boats submerged buoyancy is countered by the submarines weight it is said to be neutrally buoyant, or, in ‘submerged trim’.
With a statically diving submarine, such as the SEAVIEW discussed here, its weight is variable. The submarine takes on enough weight (in the form of ballast water) to counter the buoyant force presented by those structures above the normal waterline of the surfaced submarine. The submarine on the surface is light enough (an empty ballast tank) to permit those portions of the hull still in the water to produce a buoyant force capable of supporting the dead weight of the above waterline structures of the submarine. Surface trim.
This is as high out of the water I was willing to get this model SEAVIEW. To get the freeboard any higher in surface trim would have involved a massively sized ballast tank and consumption of significant amounts of liquefied gas to empty that tank (Propel – the same stuff used as an air-brush propellant).
Surface trim on the big seventeen-foot effects miniature was nearly to the bottom sill of the bow observation windows … impossibly high … which would put nearly three-quarts of the SEAVIEW’s hull sticking above the water in surface trim! I settled for a surface trim (ballast tank empty) that put the waterline just below the missile deck/hull break line as illustrated here. Isn’t she a beaut!
Permit me to put right an error I issued previously. Specifically, my observation that the SEAVIEW’s big manta-fins contributed to the SEAVIEW’s underwater roll problem, or ‘snap-roll’. Snap-roll is a term describing phenomena that evidences as a dangerously high inboard rolling rate caused by vehicle appendage lateral forces generated as the submarine enters a high speed underwater turn. Well, as I discovered lately, the SEAVIEW manta-fins actually contribute to dynamic stability of the SEAVIEW in a high-speed turn.
This constitutes not only a correction of fact, but also an apology to the Twentieth-Century Fox design staff, in residence during the pre-production phase of the, Voyage To The Bottom Of The Sea motion picture, and to my reader’s.
CORRECTION! As I was preparing this article, working up an analysis of the cause/effect issues relating to the SEAVIEW’s in- water performance – specifically, a study of the forces encountered by the canards/manta-fins at the bow as they cut through the high slip flow of water about the yaw axis, and the lateral and torsional forces these surfaces produce as a consequence of that water flow – I failed to correctly interpret a force-diagram.
(I lack the skill to employ mathematical analysis. Nor do I have the ability to instrument, record, and chart the forces on or near the body in motion. The magnitude of the forces acting on the body are unknown to me. However, I can and do ascertain direction and causation of those forces as a consequence of vehicle motion through the fluid. I graphically represent the vectors of force resulting from hull and appendage impingement with the fluid: diagrams, that when represented correctly, permit me to understand why the submarine behaves the way it does).
I mistakenly inverted the direction of the torque moments present at the tips of the SEAVIEW’s manta-fins. Which led to a flawed analysis, a dumb mistake, that led me to declare in this forum that the SEAVIEW’s manta-fins exacerbated the unwanted, sometimes dangerous rolling turn. A wrong statement!
So, here’s the straight poop: In fact, the manta-fins produce a counter torque (outboard rolling moment, counter of the vehicles turn) that works to negate the de-stabilizing inboard torque produced by the SEAVIEW’s sail and ‘V’ shaped ‘Cadillac’ fins at the stern. The manta-fins contribute to the dynamic roll stability of the SEAVIEW in a tight turn. As the submarines angle of attack about the yaw (turning) axis increases, and starts to ‘skid’ into a turn, a situation occurs at the manta-fin tips (those tips well below the vehicles longitudinal center of rotation) where the inboard manta-fin tip begins to generate an upward moment (force) and the outboard manta-fin tip produces a downward moment. These two forces induce a torsional moment that works to right the boat in the turn; the manta-fins improve the boats roll stability dynamically in a turn.
The only vice I can lay at the feet (fins) of the manta-fins is that they work to de-stabilize the boat in the pitch plane and contribute a great deal of flow and wave-making drag.
The SEAVIEW, as an r/c submarine, can be made to be dynamically stable in pitch and yaw as it travels submerged – without need of non-scale ‘stabilizing’ fins or control surfaces.
To sum it up:
A surfaced submarine displaces exactly its own weight of water. A submerged statically diving submarine in ‘neutral’ trim also displaces exactly its own weight of water. The difference between a surfaced and submerged statically diving submarine is simply the weight – the submerged statically diving submarine weighs more than the surfaced submarine.
We further categorize a submarine as either being a dry-hull or wet-hull type. The dry-hull employs the entire hull structure (or significant portion of the hull structure) as the watertight enclosure.
The wet-hull type submarine only uses the hull as a fairing – only those items within the hull that must be in a dry environment (crew, engines, electronics, accommodations, etc.) are encased within an inner protective hull(s).
Good examples of ‘real’ submarines that are of the dry-hull type are modern American SSN’s and SSBN’s. A nation that builds ‘real’ wet-hull type submarines is the former Soviet Union (Russian Republic); most of their combatant submarines are wet-hull (also referred to as ‘double-hulled’, submarines).
I operate most of my r/c submarines as wet-hull types. Such is the case with the DeBoer Hulls SEAVIEW kit featured here. That models hull envelope does not represent a watertight enclosure at all, water is free to enter and exit through the many flood and drain (either side of the keel, at the bottom of the hull) and limber holes – those long, near vertical slit openings either side of the superstructure.
With a wet-hull type submarine the actual displacement is the sum of the displacement of the individual items within the hull as well as the hull structure (in this case the nominal SEAVIEW GRP kit hull thickness is about one-eighth-inch). As a static diving type submarine this model has aboard a ballast tank to change the submarines weight, the means by which the SEAVIEW model assumes either surfaced or submerged trim.
Get it straight out there: the effects miniatures of the SEAVIEW were not painted ‘blue’ they were a simple primer gray in ‘color’. Never blue. Don’t paint a model of the SEAVIEW blue. So many of you armchair ‘experts’ spout off periodically, with unjustified authority, that some shade of blue is the color of the vessel. No – what you guy’s see as you watch this thing on the big or little screen is an effect of light absorption, as the red end of he spectrum is attenuated by the water. The SEAVIEW isn’t blue! Got it!?
The deeper beneath the surface of water we go the more ‘blue’ things appear. In water, as on land, what we ‘see’ is a portion of the light sources spectrum reflected off the subject. Items illuminated by sunlight (or studio lights burning at sunlight temperature, or film or prints corrected to read tungsten and other low temperature light sources as sunlight) read to our eyes a true representation of a color.
Daylight standard, if you will. That’s why you don’t bounce color chips against a custom paint mix under a light source other than the one the model will be displayed under. A gray color chip (yes, yes … smart-ass, I know that white, black, and grays are not technically ‘colors’ … just work with me as I try to make a point here) taken to any significant depth of water (assuming that the topside sun is our only light source) will throw back less red, so the object appears blue to us as that’s the significant portion of the sunlight that has the ability to punch through water. Is that chip blue? No! It’s gray – we simply see it as blue at depth. The rate of the red attenuation is proportionate with water depth. Simply put, water is a light filter that attenuates the warm end of the spectrum first. A few hundred feet down and just about all light is blocked. It’s black down there, boy’s and girl’s!
The DeBoer SEAVIEW cruising along at ‘periscope depth’. I’ve already installed the pitch vanes in the nozzles to correct for the boats natural tendency to ‘dive’ while moving ahead submerged. Now, when the ballast tank is flooded and the boat settles into submerged cruising, it does so with little operator input from the transmitter. The submarine is surprisingly responsive to sailplane deflection as I work at the transmitter to change or hold depth. ven at a ‘flank’ bell the SEAVIEW holds pitch angle well, and it does that near the surface too, where other submarines become a bit more temperamental.
The significant maneuverability problems with this boat occur as a consequence of a turn while submerged. Sea-trails taught me to ‘ease’ the SEAVIEW into high speed submerged turns. To put the rudder hard over while running at any significant speed rolls the boat into an uncontrollable dive to the bottom. (American LOS ANGELES class attack submarines have the same problem). Other than that, and the SEAVIEW’s woefully poor backing down ability, it handles pretty much like any other r/c submarine.
I’ve been reading the positive reports about the big DeBoer GRP ENTERPRISE A kit. I’m not at all surprised; I found the quality of parts and accuracy of outline of his fifty-seven-inch long TV SEAVIEW kit to be, with the exception of the sail and the threadbare fittings for the Observation Compartment interior, excellent. With a little work the DeBoer SEAVIEW kit can be built into a very good looking and running r/c submarine – it steals the show, wherever I operate it.
I write for those of you who are not content with the quality of your work. The articles I author here are rich in content; they serve as textbooks containing the methodologies, tools, consumables and techniques I use to make models. This SEAVIEW article is typical. Within these pages I show you how to take a good kit and improve on it.
Article writing is a tricky business, a balancing act, if you will. Too much dry detail my audience drifts off ; too little attention to the specifics of the craft and I failed my mission as teacher. So, I write to a formula of technical discussion and hard-nosed opinion. It helps to keep you involved. Yes, I’ll sometimes take a point a bit over the top. But, don’t be mistaken, I always say what I believe – I don’t make shit up just to get your ear.
These are the facts, opinions, loves, and hates of one David Merriman the Third. I’m the real deal. I’m your Teacher about all things relating to model building.
Throughout my adult life I faced obstacles that could have hindered my ability to practice my craft. But, I’m serious about model building; I overcame those obstacles and pressed on. I NEVER let anything, or anyone get in the way of my practicing of the craft. I continued building models in the few free hours I had, be it off-hours in the barracks, aboard submarines, ships, Dive lockers, military housing, or ‘in transit’. I always found a way to build.
At the Mariner’s Museum in Newport News Virginia. I was attending a model boating regatta where, I’m glad to report, the SEAVIEW stole the show. Owing to the near continuous airing of the TV shows both young and old spectator’s alike knew what this submarine was and enjoyed watching it run above and below the surface of the lagoon, situated at the foot of the museum buildings entrance. An excellent day, an appreciative crowd, and fellow r/c boating enthusiasts. Ellie and I had a great time. It was hard to give the boat up to the customer a few weeks later – we loved that boat!
BIBLIOGRAPHY AND SOURCES
I would be remiss not to offer you additional reading/viewing assignments to supplement what you’ve learned so far here. For more information relating specifically to the hobby of r/c submarine building and operation I have several resources for you:
‘Simply Submarines‘, Edited by Chris Jackson, Traplet Publishing, ISBN 1-900371-40-5. This stands today as the user-friendliest book on the subject available, and I recommend it to any one wishing to know more about the activity of r/c submarining. Excellent treatments dealing with buoyancy, propulsion, water tight seals, hull fabrication and many, many other topics vital to both the novice and expert.
‘Building Model Warships of the Iron and Steel Eras’, Edited by Peter Beisheim, Chatham Publishing/Naval Institute Press, ISBN 1-50114-094-3. Another collection of articles by noted model warship builders. Though only one of the nine articles is dedicated to r/c submarining, the book contains a vast array of different building techniques. If you fancy yourself a scratch-builder (or want to learn how), this book is a must-have.
‘Model Submarine Technology‘, Norbert Bruggen, Traplet Publications, ISBN 1-900371-04-9. www.traplet.co.uk/traplet/ An excellent resource for the advanced model builder already possessing a good grounding in mechanical systems, machine fabrication, and electronic design, fabrication and checkout. Many of the principles discussed are illustrated through drawings, text, and substantiating mathematical expressions. This book will be heavy sledding for anyone with less than a two year engineering school background.
I offer a sixty-minute videotape, titled, ‘Introduction To R/C Submarining’. Watch this to get a good overview of the hobby as it stands today. $29.00, includes shipping in the US and Canada. D&E Miniatures, 835 Holly Hedge Ave., Virginia Beach, VA 23452. Dmeriman@aol.com.
Another source of r/c submarining videotapes is, Ray Mason Productions, 9 Pine Drive, East, Nesconset, NY 11767. email@example.com
Of course, the topic of this article has been the fine fifty-seven-inch long SEAVIEW model offered by Dennis DeBoer. Contact him for availability and pricing for that and other fine products. DeBoer Hulls, Box 395, 608, and 13th Street, Springfield, SD 57062. firstname.lastname@example.org
Rick Teskey offers a nice fifty-two-inch long GRP SEAVIEW kit. Rick Teskey Productions, 785 Palace Place Street, Oshawa, Ontario, L1H 1M5, Canada. email@example.com. Rick also offers a twenty-four-inch wide FS-1 and a large PROTEUS kit from the movie, Fantastic Voyage. Ask him about his other projects while you’re at it.