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  1. J

    Function for the Thrust of a Ducted Fan

    You may find the information and calculations at the below site helpful. https://en.wikipedia.org/wiki/Axial_fan_design
  2. J

    Meteorology - USA Lower 48 National Winds Pattern Map Website

    For those interested but may not have found before, the below site provides a continuously updated animated map of wind pattern throughout the continental US PS I have a serious allergic reaction to a species of tree that grows NW of my location and during their pollination period I use this...
  3. J

    Wheel ground pressure vs wheel size

    What Larger Standard Tire Diameters are available?
  4. J

    Various objects under extreme g forces

    @windy miller, You are the OP so it would seem that you are the one to determine the criteria; although, I admit that is a difficult task; and, is why I posted my inquiry after pondering the issue for a while. Based upon your above criteria, it probably depends very much upon the configuration...
  5. J

    Converting PSI Pressure Loss in a Pipe to Fluid Loss Rate

    Using std 8" sch 40 PVC pipe dimensions; and, PVC material physical data from the below reference, I calculate about 0.65 Gal / 10 psi will be expelled due to pipe diametrical and longitudinal contraction while reducing the test pressure from 150 to 0 psig with an initial 1300 gallon pipe filled...
  6. J

    Converting PSI Pressure Loss in a Pipe to Fluid Loss Rate

    Do you have a pass/fail leak criteria for your pipe system; and, if so, who is determining this criteria i.e. is it your's internally or is it a customer's specification.
  7. J

    Various objects under extreme g forces

    For the sake of discussion, what would be your criteria for "completely obliterated"?
  8. J

    How to calculate this torque? (steel ball in a spiral tube)

    @Baluncore Thankfully, my issue is now fully resolved and we still have full correlation. My late night investigation just revealed that: Atan(L1/(D2*PI) = 33.995°, so using D2*PI() is the correct interpretation for my analysis. Sometimes the hardest part of getting an answer to an issue is...
  9. J

    How to calculate this torque? (steel ball in a spiral tube)

    Note: I have done multiple edits of this post so see the below post for my latest input.
  10. J

    How to calculate this torque? (steel ball in a spiral tube)

    @Baluncore , After all of our work I hardly believe I am posting this. Last night, I began to consider that I had made an error in my above calculation by using D2*π as the distance the ball traveled for each wrap of the helix in my in my F = E/n/(D2*π) calculation; when, I should have used: F...
  11. J

    Number of pins? & Point of contact?

    How do you plan to get the aluminum sheet to conform to the pin set's profile contours?
  12. J

    How to calculate this torque? (steel ball in a spiral tube)

    @vxiaoyu18 , Hello, from Houston, Texas, USA, the temperature is 23° C and it is raining. I am happy we managed to find a solution for your issue and learn a bit for ourselves as well. This is what worldwide collaboration can achieve in solving problems . It is a shame that some of our...
  13. J

    How to calculate this torque? (steel ball in a spiral tube)

    @Baluncore , I had no doubt that your solution is correct; but, if my actually would match it results. At the same time, it is nice to have a correspondence of two methods. This morning I fell into the mode of: Well, if my other method wasn't going to work then it was time to grab sometime off...
  14. J

    How to calculate this torque? (steel ball in a spiral tube)

    @Baluncore I submit the below for you review and comment ( I have no confidence it is fully accurate; but, the 45° correlation is interesting)
  15. J

    Ethical Discussion -- Engineering used to create innovation versus destruction

    I think in all such cases the issue comes down to personal integrity and the definition of that can vary considerably from one society and one individual to another. For engineers, I believe they must always be consider the consequences of their choices of professional activities; but, that is...
  16. J

    How to calculate this torque? (steel ball in a spiral tube)

    @Baluncore I now believe you are correct, another quick review of my method now convinces that there is no simple geometric calculation solution to this issue; and, beyond that all I can say is that to me, what you have done is amazing work.
  17. J

    How to calculate this torque? (steel ball in a spiral tube)

    @Baluncore I am glad to see your calculation. Well done. Now, it is time for me to see if I can develop a realistic version of mine for comparison. Obviously my final q equation should be in line with your's.
  18. J

    How to calculate this torque? (steel ball in a spiral tube)

    The issue was that when the helix axis becomes horizontal α = 0°, that is the point at which there will be no torque on the helix due to the ball wt. and my current program does not do that. I am now going to work to correct that issue. That is correct.
  19. J

    How to calculate this torque? (steel ball in a spiral tube)

    You are right, I got s and .004 switched somehow in the above equation. I think I need to back away from this for a bit to clear my mind.
  20. J

    How to calculate this torque? (steel ball in a spiral tube)

    Above you state that the ball "radius" is .045m but the: helix tubing inside diameter = .5*(D3 - D2) - 2*s = .5*(.226 - .118) - 2*.004 = .046m So is the above a typo and ball "diameter" = .045m
  21. J

    Torque required to spin a hollow cylinder

    The torque you calculate from your I equation is the torque required to accelerate (or decelerate ) the rotational speed of the pipe from one rpm speed to another rpm speed; but, must also include any external rotational resistances, such as the pipe's supporting roller's contact and bearing...
  22. J

    How to calculate this torque? (steel ball in a spiral tube)

    @Baluncore, Good catch, I understand your point and you are correct. While first developing my calculation, whenever α rotated below α (34°) I was getting negative tangent force values, so I worked out a method to correct that issue. However, while now looking at a diagram I drew today, it...
  23. J

    How to calculate this torque? (steel ball in a spiral tube)

    Well I have a new analysis (much better than my last effort) that seems to work but does not correlate with the Bernoulli or a modification of that equation as discussed above. The sin(α + β) equation simply converts angle inputs in terms of "β" to be converted into an equivalent rotation of "α"...
  24. J

    Time-dependent axial deformation

    Other than a force from an impact force being resisted by the inertia of a body you can not create a force on an object without a simultaneous force from the opposite end. From here I am going to leave to the other forum members to address this with you. With only one other viewer than my...
  25. J

    Time-dependent axial deformation

    "the fact that forces propagate at the speed of sound in solid materials" A contact shock wave will propagate through a rod at the speed of sound of the material; but, I am not sure that is true for an applied force which is applied at both ends of the object and will simultaneously and...
  26. J

    How to calculate this torque? (steel ball in a spiral tube)

    I fully agree. On the issue of the cancellation of the radius, I observed that in the Bernoulli formula discussion but was unable to really comprehend it; so, I need to go back and take another look at that issue.
  27. J

    How to calculate this torque? (steel ball in a spiral tube)

    Good work, I also see that you revised the helix pitch angle to = asin(L1/.44 (one wrap of the helix coil)) = 33.99°, which seems to make makes sense to me as well.
  28. J

    How to calculate this torque? (steel ball in a spiral tube)

    I have calculated the torque based upon the Bernoulli's method and there is a problem for your application and there is an issue for it relative to your application because as α approaches 90° its calculated torques for your ball M*g increase unrealistically, i.e. for α = 80° its calculated...
  29. J

    How to calculate this torque? (steel ball in a spiral tube)

    No problem It was strictly a terminology issue. Below is a formula I have developed based upon my last best theory (i.e. the pitch angle and tangent force determined with the helix axis vertical and then modified by the the helix angle; and, the ball contact radius being from the helix axis to...
  30. J

    How to calculate this torque? (steel ball in a spiral tube)

    I am working on an equation for the torque and noticed that the above dimensions in your Post#31 do not appear to be correct because they indicate that the helix tube length is shorter than the helix length. What am I misreading? Edit: I used the calculation to determine the tubing length and...
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