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    Wood burning train

    Locomotives and ships converted away from coal and wood burning engines mostly because the labor costs were much less with either a diesel or a gas turbine. This is the same reason ships got rid of their sails.
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    Why air flow created by ceiling fan goes downward?

    Mine are reversable, so the air could go either way. Look at the pitch on the blades and compare it to an airplane propeller.
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    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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    Maximum elastic energy in rope

    The dynamic kernmantle rope used for fall protection by climbers is specifically designed to absorb quite a lot of energy. To complicate things further, the climber has a whole lot of choices as to which rope to buy, each with different energy absorption characteristics. That is why the rope...
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    Power Transmission, Gear, Pulley

    Lots of ways to do that. The question is which means works best for this application. But then you have not told us anything about this application except the input and the output. The idea to look into block and tackle design is a good one, and the most obvious. But by the time you figure...
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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...
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    Gear ratio - Does it matter how you achieve it?

    An engineer starting a clean sheet design has a great many factors to consider before deciding how he/she wishes to configure the overall system. We already have much good information in this thread. I see nothing to argue with. So I’ll add a few thoughts based upon my experience. Heat...
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    Man-made vs natural flight

    This should be an interesting discussion. I look forward to following it. But one thing to consider is that with airplanes, the speeds are much higher. That means that sudden changes in direction or speed are seriously limited by physical considerations of F=ma. Some aircraft will routinely...
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    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...
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    Medical Why is ingesting salt bad?

    I'm an old guy with a blood pressure problem, so I've talked this one over at length with my doctor. I need some salt for my body to function properly. The trouble is that my normal diet provides much more than I need. So he told me to cut down. Then I get hauled to the emergency room in...
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    How to find the weight of an object given the force

    PhanthomJay is right. It would help to draw a free body diagram. You will also have to either know where the CG of the door is, or assume it to be in the center of the door. If that be so, the weight will work out to twice that required to open it. (Drawing the FBD and working the equations...
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    Tire pressure problem

    Back when I used to work heavy equipment, civil engineers would often ask me how much pressure a piece of equipment applied to the ground, so that they could design a concrete slab to park it on. I've seen all sorts of schemes to measure contact area to divide the axle weight by. But that...
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    Number of bolts required for a flanged coupling?

    You already have much good help in finding the simple solution, but it should be noted that in my experience shaft imbalance often becomes the dominant factor in real rotating flange design. Either because of a manufacturing error or because of a potential mechanical failure.
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    Thoughts balloon rocket launch

    Launching from altitude saves on total fuel required to reach orbit. Balloons can go much higher than you indicate. But so far, taking an airplane ride for an air launch seems a better idea. A few systems have done that. They can be placed with more precision and they can impart an initial...
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    Siphoning problem

    From what you have here, you can calculate only the pressure difference from one end of the hose to the other. You need to go back into your book and see how to get water flow rate given pressure and tube diameter.
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    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...
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    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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    Is existing relativity 100% correct, or are we waiting for something better?

    Why would we ever think that we have found the final absolute truth in all regards? Many have thought that about many things in the past, only to finally have someone expand our collective knowledge base further than most thought possible. Putting the sun at the center of the universe in the...
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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...
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    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...
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    Scaling an Axial Compressor

    Probably. But not from this phone. I'll get back to my computer tonight.
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    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...
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    Can you set the air on fire?

    If you get it hot enough, the nitrogen will oxidize. But when people make a statement like this they are really talking about something like a fuel/air bomb, where you fill the air with a flammable vapor and light it off.
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    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...
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    Punch speed and exerted g's

    The impulse delivered in a punch has very little to do with the speed or acceleration of the fist, and much more to do with what the puncher does with the rest of his/her body. A trained person can do much more damage with an elbow strike than with a punch, yet the speed and acceleration of the...
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    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...
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    Heat transfer in deep space

    Enthalpy gives a good answer, so I won't repeat it. You might Google the Space Shuttle to see how they got rid of heat. They dumped a huge heat load via radiation. The radiators lines the inside of the payload bay doors. That is why they were always in such a hurry to open the doors and...
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    Air burst testing with concrete (scaled down)

    Sounds like you might have to build a pneumatic cannon. Maybe with an intensifyer.
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    How does a shock absorber work or should work?

    I find it interesting to get engineers and physicists involved in the same discussion. One is concerned with the pure science, while the other with practical application. As an engineer I use the science to the extent that it is useful, as often it is. But other times I do stuff simply...
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    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...
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    Skydiver balloon

    Could fill it with Hydrogen, which is lighter than Helium. The balloon will not burst at the desired height because it is designed with enough surplus capacity to contain the gas after it expands.
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    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...
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    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...
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    LIL 5 year old boy falling a 50 feet to another persons arms

    You don't show your work, but I got a similar answer.
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    Apparent Weightlessness

    I don't think it was a part of anybody's design constraints to achieve apparent weightlessness on the Shuttle. That was just a consequence of achieving a stable orbit.
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    How does a shock absorber work or should work?

    The really nice thing about viscous damping is that it is linear. Friction damping is called Coulomb damping. An example is found commonly in a washing machine to damp out the drum during the spin cycle. Another is the anti sway mechanism in a trailer hitch to prevent a trailer from fish...
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    How does a shock absorber work or should work?

    There are many types of shock absorbers in many types of mechanical designs. All have one thing in common, which is that they absorb energy. The viscous damping you site absorbs energy by heating oil. Other EA systems absorb by friction, or by deforming material, or by tearing it. A common...
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    Power generated by water flowing over a dam

    The simple answer to your question is that water flowing over a dam generates no power at all. But to figure potential power generation, figure power flowing into the turbine from head height and mass flow rate going into the turbine. Then figure power of water flowing out by the flow rate...
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    Propulsive Efficiency

    At cruise, the ideal would be to have an exit velocity one mph higher than the air speed. We can’t quite do that, but that is the theory. The most subsonic engine would be to have a large fan with as high of a bypass ratio as possible. Then nearly all the thrust will be from the huge mass of...
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    Firebrick wrapped with aluminum foil

    Any one of several things can happen since we are getting close to the melting point of the aluminum. At the very least it will deform and maybe fall off. It will certainly oxidize rapidly, which will result either in it turning to powder and falling off, or it could catch fire and burn away...
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    Firebrick wrapped with aluminum foil

    Is the burner hot enough to melt or burn the foil?
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    News Public opinion regarding US Gun laws.

    Ben: honestly, I don't normally think about it any more than I think about how many hammers a carpenter might own. I attended a funeral for a very old lady who was much loved and well respected in the community. She had a large extended family and they all came from out of town. They were...
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    Pushing a car & rolling resistance of tires

    That is a reasonable number for rolling resistance, which relates to the coefficient of dynamic friction. It would take more to get the car started. Think of a locomotive, which could never start a train of cars at the same time because the coefficient of static friction is too high. But...
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    News Public opinion regarding US Gun laws.

    Gun laws vary a great deal from one state to another. Nobody knows how many we have. Your number is probably for registered guns. Most estimates I've seen are about 2.5 guns per person. From my anecdotal experience I'd say it is probably higher. Most folks I know have at least one or two...
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    Engineering I was VERY interested in aerospace engineering, but everyone tells me

    Anything in the energy field is full of many opportunities for a young engineer. Petroleum engineering has already been mentioned. But aero guys are in great demand in the gas turbine and jet engine world, and they are very hard to find. Billions are being spent to develop new science...
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    Lack of what you can tolerate?

    If those were the only choices, I'd stay single.
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    Egg drop help (Design choice)

    I've seen the cone idea work well for an 80 ft drop in which you win if the egg survives and you have the shortest drop time. Put fins on it and let it fly like an arrow or rocket. They used several sheets of paper laminated with glue for more thickness. Edit: the cone needs to crush on...