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Mechanical Engineering

G B Reid MIMechE, SIMarEST

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Everything posted by G B Reid MIMechE, SIMarEST

  1. This made my day Dudley! The kid in me: - Fantastic!!!! The Engineer in me: - It may be able to run, but would you want it to...? The way I (have always) see(n) it is it has far too high a centre of gravity, far too narrow a track and - from the animation - a hyper extending knee joint, so if it did run, the would likely break its front legs, or fall over which - even stationary - is not a "nice" concept, but at speed... I never could "square" the design being an "all terrain attack transport".......Now the Walkers on the other hand... (AT-ST)...seem a far more "considered" desi
  2. I believe this is known as a "hydraulic bouyancy lifting engine" (the Hindenburg was an Air-buoyancy lifting engine) The easiest way to calculate the usable force is to try it out with a tube set vertically in water and catch the water that comes out over a set period of time (say 10 seconds)...the usable energy (Work) can then be calculated back from the volume of water that has been ejected. Work done is Force times distance (W = Fs). The volume of the water lifted would be linked to the mass of the water x G...this would be calculated as energy gained (PE) = mgh. With regards to t
  3. This is a system that has been used for many years to provide an upthrust in dredging. This displaced water at the top provides a negative pressure at the bottom which is automatically pressure adjusted, and very - often dangerously - powerful! The pressure needed to create the bubbles at depth is slightly greater than the depth of the water, so there is still a net loss...but that does not mean that the system cannot be utilised do a specific end...but it should not be seen as a route to perpetual motion...e.g....if you can get compressed air bottled at a sufficiently low cost, you could
  4. Pool circulation requirements are well documented in various standards, and vary depending on the geographic area...basically, UV light exposure (and intensity) of the water has a significant affect on the requirements. Once you have the recommended pool water circulation/filtration rate, it is a relatively straightforward calculation. I think from memory (so may be completely wrong!) for a low use pool in the UK there was a minimum filtration rate of 3 x volume per 24 hours...but (again from memory) on my kids (very large) paddling pool I ended up going for 8 x volume due to surrou
  5. Bob I have been an engineer for the last 30 years, and I still do not specialise...for me, there's just too much I find interesting! (Certainly in the UK,) many companies offer "Graduate Schemes" to help address exactly the predicament you find yourself in. These take you into the real world and offer additional training where you will utilise your degree skills and knowledge and develop the necessary skills to develop in engineering. You may find this helps, or you may even find yourself being pulled in other directions. One of the absolutely wonderful things about Mechanical E
  6. Hi there I'll try to help out without giving you the answer...(if I do, you'll be no better off than before!) Most of the information you have is superlative! You know the chain pitch, and the chain length. You also know the length of the drive wheel and the speed with which the drive wheel is rotating (from your text 93.33 rpm). As you have calculated the rpm of the T20 wheel, and you know the diameter of this wheel and the pitch of the chain, can you think of any way to translate this into the speed of the chain across the wheel...? If you can figure this out, everythin
  7. I would definitely head for the roller screw option - they completely eliminate backlash which - for your apparent application - would be very important. The above said, I agree strongly with DrD....discuss with your suppliers and bear in mind that their answers will be loaded heavily to get you to buy; not necessarily what is best for you, but what will be best for them. If you always have that at the back of your mind, it should enable a good, informed decision. Good luck!
  8. In short contact pressure. The Dog point you would tend to want to either locate in a hole, or provide resistance with minimal surface damage (such as on a retractable height adjuster on a stand...it will grip, but not damage) The cup point will dig in to the surface a little...providing a little firmer grip at the "cost" of damage to the surface. Generally more used for semi-permanant fixing. There are various other ends available too!
  9. Interesting project... ...I would be inclined to use the pendulum to build energy in a store - such as a spring or elastic band - in order that it acts as a sink and releases. You use the basic F=ma...so you can increase the F.... the trick would moderate the release so that you don't loose it all in wheelspin... Thinking aloud....you could use the pendulum to ratchet a gravitational potential accumulator which would naturally release the energy in a controlled fashion giving maximum acceleration while preventing wheelspin...? Good luck!
  10. Of course they can cause vibrations...it is exactly the same as a flute! the AMPLITUDE of the vibrations, however, is going to be so low as to make them negligible! It is likely to whistle, but the only ay it could be anything other than a minor peculiarity is if it hit a resonant frequency...which SHOULD be checked for as a matter of course... (Tacoma Narrows Bridge)...check your shell frequencies and you should be fine.
  11. The beauty of Engineering is its cross-disciplinary nature. I wouldn't suggest an architect design an aeroplane, but a structural engineer could!
  12. I had a look round and I can't find anything definitive. I always used to find the GRC a great resource, but its become a nightmare to navigate...this may be a start... https://www.grc.nasa.gov/www/k-12/airplane/shaped.html I would suggest it's a hybrid. On a flat plate, you have the face effects, and then the vortices draging against the back. This will have a "resolved face effect" and the same rear vortices. You may be able to find a reasonable facsimile by combining the two..? Good luck!
  13. Hi DrD Thank you for offering to assist! I was undertaking a personal development course, and had not been supplied the "bridging material" that was essential for understanding. This lack of bridging manifested as difficulty in Taylor and Binomial expansions...but it turned out to be a lack of fundamental understanding of the subject which was addressed when the bridging materials were eventually supplied (six months after the start of the course!) I got a very good pass, but not the grade I would have got had I been supplied the full content in good time! C'est la vie!
  14. I agree with Abdulrahman-1....there are a couple of other observations though.... From the images (which are not overly clear where I would like to look...), there appears to be a LOT of iron filings in the female gear..although it may be the way the light is reflecting... They SHOULD NOT BE THERE and erosion of the gears should have been picked up during routine maintenance. Also, there appears to have been some sort of fluid ingress to the gears...neither should have rusted, and both show evidence. The grease should have kept the fluid out, and at worst allowed "black" rust due to
  15. Hi Zhwan. I myself am a member of IMechE. I cannott give you advice specifically on the form as everyone's experience differs, so it would be unique to you. The accompanying notes that are available for the forms are very useful in indicating what the Institute is looking to see...but by far the most useful assistance you will get is from the IMechE membership department themselves. They are very helpful to prospective members and are very keen to grow their membership....that said, they do also want to maintain standards. They will help guide you through the process. Good luck
  16. Okay...first you need to get your sketch right...it is important on this as the overhang (the "loading doorway") is a counterbalance that ensures the load is only applied in the correct way against the rollers....don't forget the cantilever masses either. Once you add the counterbalance the rollers will be loaded in the correct way and it should simply be a case of taking moments - both sides as a double check. Good luck
  17. It is difficult to say for certain, but normally in motors of any sort, the windings overheat and the varnish breaks-down (either burns off or melts) resulting in localised short circuits, identifiable by reduced resistance. ...I could be wrong, but your figures seem to back this up!
  18. One of the most popular - with huge amounts of evidence on its accuracy - is ANSYS....but there are many: COMSOL and NASTRAN at two others I've used int eh past...all three are excellent! Be warned through....FEA (or FEM as you term it - "Analysis" or "Modelling" depending on the acronym used...same thing though) is fraught with dangers! if the constraints are set incorrectly, you can get figures that look right and even seem right, but are completely wrong! NAFEMS - the regulatory body for Finite Element Modelling - recommends NEVER undertaking FEA until the hand calculations have
  19. Okay....this is a bit of a role reversal....I'm far more used to offering guidance and answers than asking the questions, but here it goes.... Can anyone give a reference to a good, easy-to-follow(!), text of Taylor and Binomial expansion of Differential equations? Specifically that used in "Variational Calculus". This is something I have covered in the dim and distant past...and as the saying goes..."it's not what you know, its what you think you know and don't realise you have forgotten!"...alas, it appears I have forgotten! I have some texts on the subject, but alas insufficient
  20. Hi there! This is definitely NOT advisable! The roof is calculated out for the wind loading and the snow loading (as appropriate) with a margin of safety....it is NOT designed to be loaded in addition to this...not without appropriate calculation and checks! If you add static loading to the roof, it significantly lowers the design load of the structure from "environmental Factors"...basically, if it snows, it could collapse, if it is windy it could collapse and if there is a sandstorm (as appropriate) - Insurance would not pay out in a failure of this nature (not to men
  21. Very simple....no snow loading, so.... ...Determine your static load by means of "worst case hail or sand loading"...corrected for angle of roof. Calculate your bend as a simply supported beam (Roark's formulae by Young is a good source for bending...) and add additional support and reinforcement as required to ensure within your tolerance (may be local building regs. or use Eurocodes or US codes as a guide if not available - there are more favourable ways of getting a headache than having a roof fall on your head!). Calculate the vector loading from a single side of the
  22. What you seek is a pipe flaring tool - sometimes known as a pipe swaging tool...they are commonly mechanical, but are available in hydraulic...I haven't seen a pneumatic version, but there is no reason why this shouldn't be available too...particularly for use around Oxygen pipework (hydrocarbons spontaneously ignite in oxygen so you would avoid the use of hydraulics in case of an oil leak). Hope this helps
  23. hmm...not quite following this...can you write the equation mathematically using brackets to ensure clarity...?
  24. this image is not of high enough resolution to analyse...but it does look like a combination of cyclical crack propagation (fatigue) and overheating...can you upload a high res image in jpeg?
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