Missing Figures
In The fall of 2004 I purchased a boat and outboard. The company that built the boat also had the responsibility of mounting the out board. Unfortunately the company built the transom of the boat to high and this had a major effect on the boats performance. With the prop so close to the water’s surface the out board would ventilate ever time I tried to get the boat up on step. It would also ventilate on tight turns at high speeds. Unless I wanted to ship the boat back down to Seattle for modifications I would have to find a propeller that would operate effectively near the surface. The follow is some of the things I learned while solving this problem.
As the propeller rotates (fig 3-1) it forces water down and back as this is happening water must move into the void created by the spiraling blades. This creates a pressure differential across the blade- Low pressure on the back side and high pressure on the front side. This causes water to be sucked into the propeller and accelerated out the back (fig 3-3) much like a house-hold fan (fig 3-2). This action creates the thrust that drives a boat.
It is common knowledge that water boils at 100deg C (212deg F) at sea-level atmospheric pressures. Water will also boil at much lower temperatures if the pressure is reduced. This is the key to understanding cavitation. As an object move though the water at increasing speeds the fluid on the side and back of the object experiences a decrease in pressure. On a propeller this area of low pressure is on the back side of the leading edge.(see fig 3-1)
Pluse-
If this decrease in pressure is great enough it can cause the sea-water to boil (Vaporize). Once these bubbles of vaporized water travel down current to the front of the propeller they enter the high pressure side of the blade and are condensed back into liquid very rapidly. These small implosions of water vapor can cause cavitation burns on theblade and lower unit of the outboard. (see fig 4-21)
4-21
From a functional stand point these bubbles can compromise the outboards performance. As the water vapor travels from the back to the face of the blades they can decrease the water load on the prop (water contact surface with the propeller blades).
Design the turtle brought up ever before seen challenges. You could not use candle for light as the flame will use up air. Designers need to find way to move on all 3 axis. Lastly and most importantly it had to be airtight. There were unique solutions that to us now seem obvious. To solve the light issue a type of wood fungus called fox fire, this created its own issue in that if it fisted over it would stop working meaning that the mission would have to go forth in summer. To move on all the axis the torte had 3 impellers, one on top and 1 on either side. The craft also had a rudder. Moving up and down was achieved by having a tank in the bottom that could be flooded with water to sink and pump water out to rise meaning that you can change the amount of weight. Making a watercraft was basically done by building something that they already knew would hold water a barrel, essentially the turtle was a large barrel. Another design element was the lead keel that kept the craft upright.
Thus Sealed Air is situated at a critical standpoint. It can either continue to deal exclusively in the manufacture of high-end coated bubbles emphasizing performance over price, or segment the market by introducing an inferior, inexpensive uncoated bubble. To this end, this report will analyze the industry, competition, and company internal environment to assess the viability of targeting this low-end market segment. A strategic marketing plan for launching an uncoated product will follow.
American author, Stephen Crane often wrote about different predicaments that his fellow men encounters. “The Open Boat” is a fictional account of his experience as a correspondent shipwrecked while on expedition to the Cuban revolutionaries in 1897 (http://www.poetryfoundation.org/bio/stephen-crane) where he spent over 30 hours on a life boat with three other passengers. This realistic story depicts how four men are forced onto a 10 foot dingy after their ship sinks. Crane takes a realist approach when describing the natural elements such as unsettling winds and the raging seas which represent the uncaring and unforgiving nature of life. Clearly, Crane narrates the role as the correspondent, while he provides dialog to provide an understanding on how the other passengers are feeling. “The Open Boat” demonstrates that man cannot survive the natural elements and hardships while isolated in the sea without an understanding of nature.
Personal Watercrafts or "jet skis" are basically Personal Watercraft (PWC) are basically small inboard boats able to travel at high speeds due to large amounts of power and very light weight. Alomst all PWC's are under 600 lbs and most of todays PWC's have at least 90 hp.Not only are PWC's some of the fastest water vehicles they are also some of the most maneuverable water vehicles. This is because PWC's propultion is based on a jet that also is it's turning mechanism. When the driver turns the handlebars the jet (via cables) turns in the direction of the handlebars so the stern is pushed in the opposite direction. This allows the driver to turn at a much tighter angle than traditional boats with keels and rudders.The main drawback to this maneuverability is the fact that if there is no thrust coming from the engine the ability to turn is effictively zero meaning that anytime the driver presses the kill switch (a large red button) they lose all ability to steer. This is extremely dangerous whenever an inexperienced person may drive the PWC back to dock or into shore. PWC's have no brakes and have no ablilty to stop other than turning around. They have an extremely efficient ability to hydroplane (when most of the PWC is above water) and it takes most PWC's a few hundred feet to come to a stop after being at full throttle. This is because 600 lbs + a rider is traveling at a very high speed with only minimal friction to slow them down (since PWC's are made to travel with very little friction).
For a plane to create lift, its wings must create low pressure on top and high pressure on the bottom. However, at the tips of the wings, the high pressure pushes and the low pressure pulls air onto the top of the wing, reducing lift and creating a current flowing to the top. This current remains even after the wing has left the area, producing really awesome vortices.
Pressure relief valves are used to safely contain pressurized gases and liquids. Throughout the years there has been an increased demand for safety in industrial and other related operating practices. These valves are one of the many devices that have been created in conjunction with standardized design and operating practices, for the provision of this very protection. In the past, vessels that now would obviously require relief valves were heated often resulting in drastic increase in pressure within the vessel. This resulted in an extremely dangerous outcome physically for all the parties involved.
The boat floats on the water according to Archimedes Principle which states an immersed object is buoyed up by a force equal to the weight of the fluid it displaces. The force applied downwards by earth’s gravity coupled with the upward force of buoyancy allows the boat to float. The boat consists of separate components each having their own center of mass, or center of gravity. The boat, the occupant(s), the engine or oars, and the fishing gear all combine to create a whole unit. The center of mass for the whole system is the average of the center of mass of each component. These components may move relative to each other but as a whole cannot change its velocity or momentum without the application of an external force. Newton’s first law of motion states that an object at rest stays at rest unless a force is exerted upon it. For the boat to move through the water a force must be exerted upon it. The forces that move the boat can be the current of the water, the rowing of the oars, the engines propeller, and wind. As the boat moves through the water a Doppler Effect is created. The Doppler Effect applies to all
This chart shows the relationship between the fanning friction factor and the Reynolds number over a wide range of flow rates, from which the roughness parameter (e/D) for the piping system can be estimated.
Take your manufacturing process to the next level with STOBER Drives ServoFit motion control applications.
To understand how this motor works, we must understand the relationship between electricity, and magnetism or simply put electromagnetism. Direct electric current in a simple description: There are two requirements for current flow. The first is a source of electrical potential energy or EMF (electro motive force,). The second is a conductor that provides a complete loop to carry the current. The reason a conductor will conduct is found on the atomic level. A conductive atom’s valance shell is not completely full electrons will flow from atom to atom because of this. When these electrons move from one atom to another that is electrical current (a brief description that is).
Most people have some sort of familiarity with submarine crafts; most of which are most likely related to the navy. This is a very accurate depiction of submarines, as they are primarily used for this, however, they are used in areas of scientific research as well. The purpose of this web page is to go into the history of the submarine to see how it has developed over time. We will also look at how a submarine works, from a physics standpoint.
Anytime you're out in the water there is a chance something dangerous will happen. People can become stranded without a way to reach shore. Sadly anytime you are in water there is a risk of drowning, yet most drowning incidents occur in freshwater. It is smart to always be prepared and safe when near water.
Capillary action can only occur when the adhesive forces are stronger than the cohesive forces, which creates surface tension in liquid. The kinetic energy produced when the liquid is heated, allows the attractive forces between the molecules to weaken and this causes them to move past each other more freely. This results in the liquid flowing more easily. Therefore temperature increases capillary action and capillary flow because of the decrease in cohesive force. The intermolecular forces between the molecules are less packed due to the increase in temperature and the surface tension in the liquid will decrease as the temperature increases and this will help the flow of the liquid through the capillary tube.
Anytime you are out in the water, there is a chance something dangerous will happen. People can become stranded without a way to reach shore. Sadly, anytime you are in water, there is a risk of drowning, yet most drowning incidents occur in freshwater. It is smart to always be prepared and safe when near water.