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  1. K

    Decreasing Motor Torque Requirement With a Gearbox

    my goal is to rotate a 500kg(1100lbs) load to 90° in 1.5 seconds. This would be only the first question I would ask. Remember that work is defined by a mass moved over a distance in a specific time. So the bottom line is; no matter how you get there if you move the same mass the same...
  2. K

    Old plumber wisdom, is he right or not?

    Jonathan 212, I have run into the same scenario before. I believe I can also show were the old timers get their perception. Often old time plumbers did not run calcs. They operate from a series of "Rule of Thumb" basics. One of the things that used to be used (and still is in some circles) is...
  3. K

    Why isn't the Pneumatic Tyre used for suspension?

    As Chemair pointed out there is a lot more to vehicle comfort than just softness. I also rode a large Harley for many years. One of mine was a chopper that was converted to a "strut" rear suspension where the rear shocks were removed and replaced by a rigid post. It rode wonderful on a straight...
  4. K

    Automotive Car on Fire - Causes and Possible Methods of Prevention

    A couple of things to bring up as I am a late arriver on this thread. First, the incidence of vehicle fires. You would have to show that the increase of fires is greater than the increase of number of vehicles on the road. The evidence that I have seen is that when corrected to an incidence per...
  5. K

    Damping a trampoline on the 2nd floor

    Rocksolid, What is your physics background? Willem2's input is very good. The concept is impact impulse. With each bounce there is a force that needs to be dissipated (and returned in the case of a trampoline) which is what is bending the ceiling. Anything that you can due to divide the forces...
  6. K

    Automotive Idling or turning the engine off?

    Russ_Waters, Thank you for that. If I stay away from url shortening I cannot bring either to a direct download link. As Russ stated the Energy journal study is about peoples actions and perceptions. It can be searched in Volume 37, Issue 8, pages 2881 -2888 from August of 2009. If interested one...
  7. K

    Automotive Idling or turning the engine off?

    Hello again, There are two studies I located quickly one was published in the Journal of Energy policy in August of 2009. I could not find a good web link but it is visible and downloadable at : https://bit.ly/2wGkrcp There is also a study by SAE (this is the same one previously...
  8. K

    Automotive Idling or turning the engine off?

    It will take a little bit for me to track the studies down the last few that I have looked at showed that a gasoline engine broke even for energy at a 7 second shutdown and that Diesels broke even at near 10 seconds. There is some justifiable concerns with reduced starter motor life when city...
  9. K

    Storing Heat from a Radiator

    Two immediate thoughts come to mind. One you are definitely on the right track to introduce some thermal mass. As noted earlier a thermal wall of some type is of great use. It will warm when it is cooler than the space it is in (which should be close proximity to the burner and flue). Often...
  10. K

    How effective is a pocket car window breaker?

    That would be your answer. Very few cars have laminated side windows. The trend started appearing in 2017. The primary changer was that high end cars that were trying to improve the safety ratings needed better survivability in the difficult side impact tests. By using laminated glass the side...
  11. K

    How effective is a pocket car window breaker?

    You are correct, the antenna is on the outside. I think I mentioned it in the last paragraph of my first post ( # 28 of this thread I think). I use it almost as often as I do my punch. Here is a quick youtube of the idea, FactChecker is also correct it is about the sharpness of the material...
  12. K

    How effective is a pocket car window breaker?

    Your asking a very good question. I do not have any studies to share but I do have some input and good anecdotal evidence. First would be the configuration. Does each of the ones you are looking at have the same cutters and window spikes? Second would What are your realistic plans for...
  13. K

    How effective is a pocket car window breaker?

    Note two. The film on the inside of the window does not affect the hammer strike. That film is a simple low strength polymer. The high point load of the impact will immediately breakthrough and strike glass. The shattering effect that tempered glass exhibits is caused by a process similar to...
  14. K

    How effective is a pocket car window breaker?

    The previously mentioned spring type tools are very reliable and they work very well. Any of the side windows on your vehicle are tempered and they will come out in their entirety. Window films are a thin open polymer layer and they will tear free easily. One advantage is that tempered glass...
  15. K

    Automotive Points ignition output voltage and length?

    There is a peculiar form of truth to this. Electronic control units can provide much better engine control than older style engines. They are better at providing economy and performance. However there is a lot to be observed from the advantages of modern engines and the way they also have...
  16. K

    Automotive Air-fuel ratio

    To tack onto Jack Actions comment about more cooing as there is more matter present to carry away the heat when an engine operates at a higher stoichiometric ratio. One must also consider that more matter in the same volume increases the density. A Higher density medium can transmit more power...
  17. K

    Springs to reduce the torque?

    It is reasonable to carry a motion to an extreme and consider the overall effect. In your case I believe I see your point in easing the force at extreme limits of motion. Adding a spring to "soft couple" a motor to an appendage can function but most often is done with a resilient coupling...
  18. K

    Exotic Bicycle Designs and Engineering

    UPS is rolling out a pilot program in Seattle and select other cities around the world. Novel in that they are a bike with a trailer. Load both cruise to the area. Drop the trailer. Return transfer loads and repeat. Interesting.
  19. K

    Misc. Interference Between Two Speakers -- Real Life Version of a HW problem

    Sorry about the delay in my getting on this thread. Are you still projecting this idea? I have had good results doing reinforcement projects for demonstration. One of the most important points is that humans have Binaural hearing. Start by calculating the wavelength of the Hz sound you are...
  20. K

    Automotive Why is carbon fiber safer than steel for the cars?

    This is an excellent question. It is one that involves thinking outside of our perceived limits. First a little side note for the engineering types among us. There is no "absorbing" of force, it can be dissipated, redirected, or translated but not absorbed. I am sure there are other ways it...
  21. K

    Automotive Why is carbon fiber safer than steel for the cars?

    My current field of work is in emergency services. In that respect we work to evaluate injuries with respect to three separate collisions. The 'first" collision is the vehicle encountering another object. This is the impact that initiates the chain. The "second" collision is the body...
  22. K

    How to approach the design for a boat step by step?

    Anorlunda is correct. There is no difference in determining the characteristics of the stability profile. Do be very careful that you do not fall into the common mistake of calculating one hull and not consider the other hull. The supplemental effect is amplified by the separation of the two...
  23. K

    Power required to compress air in a gas turbine

    I would have to do a little more to show the actual calculations. But Russ Waters was almost exactly right on the 2/3 power finding. I know from working in industrial use of a LM 1500 which in Aero use is a J79. These old school engines produce approximately 45,000 hp at the combustors. The...
  24. K

    How is DWT in container ships achived?

    The DWT is a rating not a limit. How they get to that point is a complicated process. I would recommend getting a little more understanding of Metacentric height or GM. The heal angle of a ship and the righting moment developed at that angle is related to the height of the center of Gravity...
  25. K

    Wood/Glass/Metal Soldering steel

    Tom G hints at one of the most common issues I see. Solder will flow from a place of low temperature to a place of high temp. It will not however flow when it is not liquid. To get an effective solder joint make sure the base metal is fully up to temp. When one accepts the temptation to melt the...
  26. K

    Automotive Automotive MAF sensor vs temperature

    Is this a kit type DIY ECU or are you creating it? You must also understand that the ECU operates with multiple feedback loops. This is one of the simpler ones if any of them are. The MAF determines the amount of air entering the engine. The throttle position sensor establishes what power level...
  27. K

    How to ventilate a room with no windows with one inline fan?

    The rest of the design stuff is mostly in the acoustic part of your design. As Anorlunda pointed out the more bends the more friction. This friction will create noise (a very small amount but observable at some level) however a larger baffle arrangement will allow more external noise. You will...
  28. K

    Pressure upstream and downstream of a filter

    In a nutshell the rest of the answer can be predicted by the use of the system and the flow rates. A clogged filter will act very similar to an orifice plate. A good system design will have some allowance for clogging and still maintaining system serviceability. This "overdesign" combined with...
  29. K

    Puzzling issue in gas mileage improvement

    Thanks again for all the good input. It looks like we mostly centered on the same point as was of concern to me. That being that 2mpg was a 10% change in average energy. Thus the look for a cause. Ranger Mike thanks for that link . I was not aware of that study good info. As of today I found...
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