Recent content by NTW

  1. NTW

    B How many horsepower?

    The power mentioned above for opposing rolling resistance and the drag is the minimum power needed to accelerate the vehicle to 300 mph. That acceleration will start with a high value, and continuously decrease as the speed increases, till the target of 300 mph is reached asymptotically. If you...
  2. NTW

    B How many horsepower?

    Not the case here, since aerodynamic drag and rolling resistance should be taken into account.
  3. NTW

    B How many horsepower?

    In my estimation, I accounted for the power lost to the transmission; thus, the 1600 HP is 'power to the ground', yes... If you have to keep that speed of 300 mph, even for the fraction of a second, you'll need the 1600 HP, for that fraction of a second... Good luck...
  4. NTW

    B How many horsepower?

    To the aerodynamic drag, you must add the rolling resistance. The rolling coefficient for tires on concrete is around 0.012 Now, for a car with a mass of 3400 lb (1544 kg) the power needed to keep the car moving horizontally at 300 MPH (134 m/s) fighting just the rolling resistance would be...
  5. NTW

    B How many horsepower?

    Assuming a frontal area of 1.5 m2, a coefficient of drag of 0.3 (a frequent value in sport cars) and an air density of 1.23, the power needed to keep the car moving at a constant 300MPH = 134 m/s against the aerodynamic drag would be: Power = drag × airspeed ⇒ Power = (½ × 1.5 × 0.3 × 1342 ×...
  6. NTW

    Could a ballistic missile be used to deliver cargo?

    I believe that a system of 'rocket mail' was used in Austria or in Switzerland, in the 1920s or so, to send letters to villages that were difficult to reach by land. And, in 1810, Heinrich von Kleist proposed (I suspect that tongue in cheek...) a 'Bombenpost' service, with hollow shells and...
  7. NTW

    Hydraulic motor-AC generator coupling

    Die Energie der Welt ist konstant (Clausius)
  8. NTW

    I Thoughts on Newton's Bucket and the relativity of rotation

    Just a comment: some years ago, I tried to read about the history of the 19th and 20th century research on the problem of inertia. There was a document, a book, by Immanuel and Benedikt Friedländer that seemed to be interesting, but in spite of my efforts, I wasn't able to find it in the...
  9. NTW

    B Jet propulsion in space?

    Perhaps all the bird wanted was a jetstream hike...
  10. NTW

    B Meaning of panchromatic

    Panchromatic is a b/w film that is red-sensitive. Older, orthochromatic films, are also b/w, but red-insensitive.
  11. NTW

    B How come weight difference doesn't cause problems in trade?

    Balance scales are widely used. The well-known 'Toledo'... Like this one... But I believe that the OP is right... These somewhat old-fashioned mass-comparing instruments have today been displaced by electronic scales that measure force, and not mass...
  12. NTW

    Parachutes for small planes -- so many lives saved...

    Well, you haven't provided a single case of a plane saved by the parachute after a low-level stall/spin. No wonder you didn't... Once you enter a spin below -say- 500 ft, you are doomed, parachute or no parachute. Not even the manufacturers of those systems dare to make that claim, because they...
  13. NTW

    Parachutes for small planes -- so many lives saved...

    If you know of a single case of a plane saved by the parachute after a low-level stall/spin, you should mention it... Extraordinary claims require extraordinary evidence...
  14. NTW

    Parachutes for small planes -- so many lives saved...

    That's not correct. On the contrary, almost all planes, specially light ones, can easily exit from a spin. It is a procedure covered in the pilot operating handbook. It usually consists in easing the stick forward and pushing right pedal for left spin or vice-versa.
  15. NTW

    Parachutes for small planes -- so many lives saved...

    Fatal accidents related to stall/spin use to happen at low altitude. If you have enough altitude for the deployment of a parachute, that altitude is also sufficient for a standard recovery maneuver. No need for a parachute...
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