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  • Users: Pkruse
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  1. P

    Cheap Hydrostatic Testing Chamber

    Probably not for depths as shallow as you are talking about here, at least from the perspective of hull design. But depending on what sort of seals you select, it may be a good practice to prevent seals from leaking. If you are very concerned about leaking, you may try presurizing the system...
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    Cheap Hydrostatic Testing Chamber

    I'd design the hull for whatever pressures I desired, and then use the lake to test it. Just weight the hull down and lower it to depth on a rope. At this point, the hull need not have all the expensive stuff installed. You are just testing the hull. Designing for these pressures is very...
  3. P

    Automotive High compression turbocharged engines.

    Yes, Kozy, alcohol burns in a manner similar to high octane gasoline. It has less energy content, but if you increase the combustion chamber pressures, the increase in efficiency can more than make up for the lower energy content of the fuel. But burning it without matching the engine to the...
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    Automotive Ideal torque vs engine speed curve

    It is easy enough to Google them. All engine manufacturers publish technical data on their engines, including a number of curves. I’m normally most interested in the specific fuel consumption curves. That tells me at what rpm I want to run the engine for various loads. Normally, the...
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    Automotive High compression turbocharged engines.

    I have little knowledge of racing engines. My experience is with practical working engines. It is common to reduce the pressure ratio when adding boost. The idea is to give the combustion chamber a little more volume. Without the boost, that would mean less pressure. But with boost, you...
  6. P

    What role can mechanical engineering play in free range farming?

    Back when I was in college in the mid 1970’s, I had a friend with a ten acre vegetable farm. Farmers call that a “Truck Farm.” He was a rather sharp engineer, and he was drawing an income off those ten acres about equal to a good engineering salary at the time by doing some creative and...
  7. P

    Diesel-electric versus diesel

    An engineer doing a new clean sheet design of a diesel locomotive has to design some sort of power transmission system to transmit the power to the drive wheels at the appropriate speed. He will make many trade off’s and compromises to find the best overall system for meeting his design...
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    Scaling an Axial Compressor

    Aleph Zero: Sorry, I could not find anything published to the public domain as to how concepts of centrifugal compressor design is incorporated into axial compressor design, to produce a more efficient hybrid that looks like a regular axial compressor to the person who does not know the...
  9. P

    Scaling an Axial Compressor

    Then it is a misconception commonly held by all the engineers who design engines for real airplanes. I don't think you can name one engine currently in production in significant numbers that I can't in five minutes walk to the desk of at least one engineer who was on the design team. If I told...
  10. P

    Scaling an Axial Compressor

    Probably. But not from this phone. I'll get back to my computer tonight.
  11. P

    Scaling an Axial Compressor

    In general, when the length of the blades gets down to one inch, it is time to switch to a centrifugal stage. At that point the efficiency of the axial stage will be less than the centrifugal stage. Efficiency is not as simple as you say. It is a function of tip clearance/blade length ratio...
  12. P

    Oil pressure as it relates to efficiency

    Ranger Mike's information on the small block Chevy caused me to think of a friend of mine who has a local reputation of building the hottest engines. Most go into racing airboats, but some into NASCAR races. It is common for him to spend 50K on parts and machine work. He is also an excellent...
  13. P

    Oil pressure as it relates to efficiency

    Agreeing with Ranger Mike and continuing the discussion: Your friend has little understanding of the science behind what he has done with his engine. It is not hard to get 1000 hp out of an engine. You can buy everything you need out of a catalog, and your machinist will know what to do...
  14. P

    Seat belt force mismatch between test data and calculations

    The calculations do not model reality well. There is no way that the structure of the automobile can transmit 60 g to the person. It will start yielding and breaking up, which absorbs much energy and minimizes loads transmitted to the person. Anything over 40 g is not survivable under any...
  15. P

    What role can mechanical engineering play in free range farming?

    One more thing that might find an engineering solution. "Free Range" normally means that several ranchers are sharing the same land. Nobody put up fences to keep the cattle on the property of one rancher. So once per year all the ranchers get together and "mammy them up." This is where they...
  16. P

    What role can mechanical engineering play in free range farming?

    The biggest problem is rounding up the cattle. That is often done on horseback like it was 150 years ago. It is also a problem getting them proper nutrition. They typically mix molasses with whatever other nutritional supplemental their natural diet might be lacking, and deliver that to large...
  17. P

    How would one calculate Tug of war forces between two vehicles?

    Like many real engineering design applications, you are missing a whole lot of information required for an accurate solution. What we so in this in cases like that is to bracket the solution with a max and min solutions. For max, assume a coefficient of friction of unity between the tires...
  18. P

    Wheel stud design for truck

    You also need to decide what type of rim you are using. For some, all the loads go thru the bolted connection, but not for other designs.
  19. P

    Need to interview an engineer for assignment!

    I do the mechanical design of gas turbines. I've worked many different jobs in the last 4 decades involving many aspects of mechanival, marine, and civil engineering. I tend to change jobs simply for the opportunity to learn new things. I've studied anything and everything that interested...
  20. P

    Force calclulations on a drum

    Center of drum to center of rope. 51 inches. But if you measure carefully, the Lebus shell will probably make that number a little different. Just measure total diameter including the rope layer and divide by 2. Then subtract one inch.
  21. P

    Force calclulations on a drum

    What sort of hoist system is this? If a crane or elevator, then all sorts of standards and requirements apply.
  22. P

    Trying to find force on a chain.

    Pwr & rpm give you torque at the motor. Multiply that by the gear ratio to get torque at the gear box output shaft. Divide that by the radius of the first sprocket to get max tension in the chain. If you have the gear box efficiency, then reduce the number by that amount, otherwise assume...
  23. P

    Boilers: Bolts and Studs

    I'm assuming that all material in this project is certified. They used the same nickel super alloys you see in a jet engine from the same suppliers.
  24. P

    Boilers: Bolts and Studs

    I saw the assembly of a high temperature Boiler Code application the other day. They used nickel and Chrome alloys for the high temperatures. I found the flanges to be particularly interesting. They were using UNF threads, which is not common in boilers, and they were using threaded rod with...
  25. P

    Costa Rica Earthquake

    We don't have a forum for Civil Engineering, so I post this here and invite the moderator to move it if it better fits someplace else. They had a very strong earthquake yesterday and today it is minor news because they had no deaths directly related to it and very little damage. One guy did...
  26. P

    What determines optimal wheel size?

    Steel on steel rolling design is much different from pneumatic tires. It is more like roller bearing design. Care must be taken to make sure contact stresses are acceptable. Wheel diameter figures significantly in that set of tradeoffs.
  27. P

    Mooring line for wind turbine model

    Or maybe a thin wire rope like that sold on fishing tackle shops for leader material.
  28. P

    Mooring line for wind turbine model

    Specta fibers might work well.
  29. P

    Adjustable spring?

    Back in the days of vacuum tubes and massive analog instrumentation, a different spring was designed for every instrument mounted in the airplane. This resulted in thousands of spring part numbers. The Russians had a different idea and mounted all instruments with the same spring. It was a...
  30. P

    Number of Teeth for Planetary Gear Train Question

    That may be true. I seem to remember something like that from my training many decades ago. It was derived from the basic geometric relations that enable the gears to mesh correctly. But your application is not the common one. You have an extra planet. So I would not use any standard...
  31. P

    Wall Strength of a Shipping Container

    If you can't drill a very small hole and patch it with epoxy, you can get a thickness measurement with ultasound. Anyone who inspects boilers, pressure vessels, or fuel tanks should have the equipment. NACE inspectors often use it, too.
  32. P

    Number of Teeth for Planetary Gear Train Question

    Any of the gears can have any number of teeth within the physical constraints of your application. I start with the desired gear ratio. Then I decide if I want to fix the ring or the planet carrier. Then I work backwards to see how many teeth I need, making sure that I remain within the...
  33. P

    Number of Teeth for Planetary Gear Train Question

    I've never seen a ring gear that was not round.
  34. P

    Wall Strength of a Shipping Container

    14 ga is common, but I've found some that are heavier. Find a machinist's depth gauge and drill a small hole big enough for the gauge. Hold a plate on one side and measure the depth thru the wall to the plate. Quick and easy way to measure the thickness.
  35. P

    Wall Strength of a Shipping Container

    Destructive testing is really rather easy. Apply the test load with a wire rope. Run the wire rope through a sheave mounted on the floor of the container. React the sheave load through the floor to ground. Then apply a horizontal load from outside the container. For a load device, I’ve used...
  36. P

    Wall Strength of a Shipping Container

    I find this interesting. I've put hundreds of hooks, racks, and shelves in shipping containers. Sometimes we would have nearly a thousand pounds hanging from one hook. I never analyzed the stresses and never had a failure.
  37. P

    Simple Hydraulic circuits

    A system should have a place where air naturally accumulates. If the cylinder is mounted vertically, that would be the place. Put the air bleed there. If in a simple system you have no such point, then don't worry about it. The air will wash back to tank and automatically purge itself from...
  38. P

    Lean burn in cars

    I have pondered that at length over the years. The only hypothesis that has survived is that the engine is working less efficiently and therefore has to work harder.
  39. P

    Dozer Engine Torque and Horsepower Calculations

    Here is another example. I have put the same engine model onto three different pieces of equipment. One required 120 HP, another 400, and another 750. This is a common industrial diesel. All applications performed extremely well, even though the manufacture killed the warranty on all but the...
  40. P

    Dozer Engine Torque and Horsepower Calculations

    Good point, Chris. I always study the books first. Then I talk with the mechanics and operators. Then I talk with the job planners and check actual records. I might find that some operators always get more work done. So I'll go figure out what they are doing differently. After I develop...
  41. P

    Dozer Engine Torque and Horsepower Calculations

    Chris: I understand where you are coming from, but in today’s environment that is rather outdated advice. The reason that fleets are hiring engineers is to do better than the book. I was an engineer for a fleet big enough to employ four and sometimes five engineers for about 25 years. Our...
  42. P

    Dozer Engine Torque and Horsepower Calculations

    This is one place where theory and practice don't match well. The reason is that it is extremely hard to model the dynamics of hitting the dirt while moving.
  43. P

    Bushes, interference fit

    Check your Machinery's Handbook. Many pages of standard tables.
  44. P

    Truck-mounted Hyraulic crane

    This would be a fun design project, and fairly simple for an engineer familiar with noble cranes. What is not so simple for someone not familiar with them is to figure out which standards and codes apply in your jurisdiction, and then performing the required tests and certifications that you...
  45. P

    Motor and planetary gears

    Motor and load will not see the same torque. They will be different by a factor equal to the gear ratio. If you are trying to balance the sum of the moments in a free body diagram, then don't forget that the difference on torque is taken out by the gear box case.
  46. P

    Controllable Force & Speed Linear Actuator

    I'd suggest dropping the concern for controlling force. Don't think of the actuator applying a specific force. The load will provide the force and the actuator will match it. You only need select one that has the ability to provide a safe margin over the max force provided by the load...
  47. P

    Electrostatic Discharge in Hydraulic Systems

    Filter systems: I can't say enough good about depth type filters installed in a bypass loop on the low pressure side. Since they handle only a small percentage of the flow, you can put a very good filter in place, and the depth type filters can contain a large amount of particles before you...
  48. P

    Automotive Significance of snap rings in a turbo

    You have already heard good answers. Snap rings are cheap and effective means of holding such things as bearings and seals in place. But a general comment about turbo machinery is probably in order. Two things cost probably the most in the design phase. They are how things change dimensions...
  49. P

    Very fast linear actuator

    I once had to design a lenses switching system in a very high dollar optical system that hangs under an F16 jet. I used a lead screw with 5 leads. Put a very expensive anti friction coating on the threads and spent a great deal of money eliminating nearly all the back lash. System has been...
  50. P

    Electrostatic Discharge in Hydraulic Systems

    Dieseling seems to be a much greater explosion hazard, and we already protect our systems from that, so I'd have no concern with ESD causing an explosion. All my high pressure filters are metal, so I'd have to see some good data before I'd worry about holes in those. I like to put depth...
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