8,097 reputation
1728
bio website en.wikipedia.org/wiki/…
location United States
age 70
visits member for 3 years, 7 months
seen 19 hours ago

BS Mechanical Engr.
PhD CS(AI)
CS Prof (4yr)
Numerous consulting jobs.
15 yr at http://www.pharsight.com
Published book on CS & several articles
4 kids, 2 grand
Pilot(student)

P.S. The picture is a Beta-prime distribution. It shows the program speedup factors you can get if you see a problem twice in 2, 3, 4, and 5 samples.


Jan
26
comment Am i trying to fly by pulling myself up by my hair?
You might try a lever arrangement, so the downwash is not hitting the scale.
Jan
26
comment Can a car steer on a frictionless surface?
@EmilioPisanty: I don't think the front wheels on a car (on the frictionless surface) can change the car's pointing direction, because those wheels are not free to precess at right angles to the direction in which they are turned, because the car cannot bank (as a motorcycle can). You would need to have a gyroscope mounted in the vehicle, and it would need to be free to take on a bank angle. The amount it would need to bank would depend on its angular momentum.
Jan
22
answered Where does the loss of kinetic energy of the wind flowing over an airfoil go?
Jan
20
revised How does a supersonic flight speedometer work?
added 69 characters in body
Jan
20
answered How does a supersonic flight speedometer work?
Jan
20
comment Alternative air transportation and magneto-aerodynamics
There have been "flying saucer" aeronautical projects, of varying degrees of success.
Jan
20
comment Helicopter, Tricopter, Quadccopter - what's really happening here? Are there generalized advantages on a small scale?
For efficiency, the longer and thinner the blades, the better. Smaller rotors are less efficient, thus less flying duration. If you have an odd number of lifting rotors, you have net torque, so you need a tail rotor. Planes with lifting rotors can hover, but planes with wings have to fly in circles if they want to stay in one place. Put all those considerations together.
Jan
16
answered How size of objects lifted by the wind depends on the speed of the wind?
Jan
15
revised transfer of heat from lower to higher temperature
added 122 characters in body
Jan
15
answered transfer of heat from lower to higher temperature
Jan
14
comment Problem regarding Archimedes Principle
It's a spring-mass-dashpot system (ignoring the dashpot). You can figure out the amount of mass, and you can figure out the spring constant (dForce/dY). Then look up the equation.
Jan
9
comment Turning an Airplane. What actually causes the circular motion in a banked (roll) turn?
@David: Your instinct is right. The tail acts as a weather-vane, which is the same as saying if the fuselage gets sideways to the relative wind, the tail (vertical stabilizer) feels that wind, creating a torque to turn the craft's nose into the wind. (Losing that tail is a good way to crash, because then nothing can stop the plane from going sideways.)
Jan
6
comment Different sized pneumatic Pistons
@TwoShorts_: I don't know what else to say. At the same pressure, force is proportional to area.
Jan
6
comment Turning an Airplane. What actually causes the circular motion in a banked (roll) turn?
@David: Neither. When you ride a bicycle in a circle, what causes the turn? It is the fact that you are leaning. That creates a sideways force. If there is a sideways force, there is no way you can go in a straight line - you have to turn. Banking an airplane and leaning a bicycle are the same thing. All the tail does is keep you pointing in the direction of travel.
Jan
6
answered What are the preferred height and diameter proportions for a rocket model?
Jan
6
answered Different sized pneumatic Pistons
Jan
6
comment Different sized pneumatic Pistons
Well then you can answer it yourself. Just suppose one piston has a surface area of 1 square centimeter, and the other is the size of a football field, and the air pressure on each one is the same per square centimeter. Suppose each one is actually a suction cup. Which would be harder to lift?
Jan
6
comment Different sized pneumatic Pistons
You mean with different area? Force is pressure times area.
Jan
5
answered Dropping Objects of Different Masses
Jan
4
awarded  Guru