7,738 reputation
1628
bio website en.wikipedia.org/wiki/…
location United States
age 70
visits member for 3 years, 3 months
seen 21 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.


Nov
12
comment Turning an airplane - coordinated turn and inclinometer (“the ball”)
@Marco: Pretty soon, we'll get told to take this to chat, but if you're in a long boat, moving at fair speed through the water, and somebody suddenly bends it horizontally, so it suddenly feels a force pushing it to the side, that's going to produce some lateral acceleration, and you'll feel it (I hope you agree). Same thing in a plane, whether or not you're in a bank. OK, I'll give you the last word :)
Nov
12
comment Turning an airplane - coordinated turn and inclinometer (“the ball”)
Gosh @Marco, my powers of explanation must be exhausted, and I assume you have read and re-read Stick and Rudder, the best little book on the subject. So, sorry I couldn't help more.
Nov
12
comment Turning an airplane - coordinated turn and inclinometer (“the ball”)
@ColinK: OK, another try... The plane hanging from the pendulum is not pointed into a hurricane, but a real plane is. Pushing the rudder to one side causes that strong wind to press more against one side of the plane than the other, and the sides are flat, so the plane experiences lateral lift, not due to the wings but due to the sides of the fuselage in the wind. That lateral lift is what the ball shows. Does that help?
Nov
11
comment Turning an airplane - coordinated turn and inclinometer (“the ball”)
@Marco: The way the pilot makes the ball move like that is by pressing the rudder this way and that, that's all. He doesn't have to - he's just showing what happens if he does.
Nov
11
comment Turning an airplane - coordinated turn and inclinometer (“the ball”)
@Marco: That's an excellent video. In addition to illustrating adverse yaw, they are showing what happens when you are in the turn, and you apply the rudder (to a greater or lesser degree than required to counteract adverse yaw). Most planes have a self-righting tendency, by design, meaning that even in the middle of a turn, you have to apply some aileron to maintain the bank, and the corresponding rudder.
Nov
3
comment What are the properties and impediments of a liquid air fueled engine?
@AlanSE: Yeah, it's hard to beat a gas-battery hybrid with regenerative braking. Then the bigger issue is the ultimate source of the energy in the fuel. Fossil - bad. Other stuff - not bad.
Nov
2
comment What alternative shapes may a rocket heading into orbit have?
It's funny that fish, if they move with any speed, all look like fish - small cross section, smooth, etc. Form follows function.
Nov
2
comment What are the properties and impediments of a liquid air fueled engine?
It's just another way to carry along energy that has to come from somewhere else - battery, hydrogen, flywheel, compressed air, etc. etc. Actually, if fluid hydrocarbons can be made in a carbon-neutral cycle (without taking away people's food), they are still probably the best, when used in hybrid vehicles.
Nov
2
comment Velocity required for Horizontal Rain
If your objective is to observe horizontal rain lines, just put a heavy weight in the back of the car, to make it tilt up. Then drive the right speed.
Nov
2
comment Force applied off center on an object
Check out Center of Percussion.
Nov
1
comment Uncertainty Principle for Information?
@Mark: You said it more precisely than I did.
Nov
1
comment Uncertainty Principle for Information?
Information theory has at least two general approaches, Shannon's, and Kolmogorov's. Also, since quantum processes are reversible, that makes information a conserved quantity.
Oct
31
comment Is there an intuitive explanation for the Southward force caused by the Coriolis Effect on rotating spheres?
I'm puzzled by it too, although there's an obvious effect. If a projectile starts at 1 meter away from the north pole and moves due east or west, very quickly it will be moving south.
Oct
30
comment Conservation of energy in objects at terminal velocities
The answers are right. When an object moves through the air, it imparts energy to the air. Just think of an ordinary household fan.
Oct
29
comment Is flying really easier on smaller scales?
Nice work, Alan, but it seems to me the concept "flying is easier" is too undefined. I mean, it's "easy" for me to climb a ladder (store energy) and then jump off (fly). An acorn does the same thing :) You seem to be focused on insects and/or battery powered robots. Regardless, why don't you take some flying lessons? It's not too expensive, lots of fun, and puts your science knowledge to work.
Oct
26
comment Is flying really easier on smaller scales?
@AlanSE: I guess so, but I think of the Pan Am Clipper versus the 172 I fly sometimes.
Oct
26
comment Is flying really easier on smaller scales?
+ Yes. The word "easier" needs a definition. A dust mote "flies" with no more energy than the brownian motion of the air. OTOH airplanes have some kind of power law that gives them more range with greater size.
Oct
23
comment Weightlessness by a parabolic flight
+ I was taught to distinguish between weight and mass, but I can see your point. If you're teaching non-technical students, that can be too fine a distinction.
Oct
23
comment Weightlessness by a parabolic flight
I can't believe I misspelled "astronaut" twice :)
Oct
22
comment Weightlessness by a parabolic flight
Isn't that a bit pedantic? It's common to say astronaughts in orbit are experiencing weightlessness. If I throw a ball in the air, while it's in the air, it's experiencing exactly the same weightlessness as the astronaught.