Mike Dunlavey

4,189 reputation

714

bio	website	en.wikipedia.org/wiki/…
	location	United States
	age	68
visits	member for	1 year, 8 months
	seen	20 mins ago
stats	profile views	415

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)

	4,189 reputation	bio	website	en.wikipedia.org/wiki/…	visits	member for	1 year, 8 months
714 badges		location	United States		seen	20 mins ago

summary answers questions tags badges favorites bounties reputation activity

518 Comments

suggestions reviews revisions comments badges posts accepts all

May 1	comment	Would there be any possibility for anyone to survive when a Boeing 747 crashes to pacific ocean with its normal cruising speed? Pilots train for dead-stick water landings, as in US Air 1549. Size of the aircraft is not a factor.
Apr 26	comment	Why is the damping force on a spring oscillator linearly dependent on velocity? Cars these days have shock absorbers that are basically dashpots with viscous drag. There was a time when cars used straight friction devices to absorb the energy in up-and-down wheel motions. It just depends what type of energy-absorbing device you use.
Apr 26	comment	Why don't we see solar and lunar eclipses often? @Firzen: The new moon is visible during the day, provided you can block out the glare from the sun. This is most easy to see just after sunset or just before sunrise.
Apr 25	comment	Equilibrium of a sphere in a water tank To put @JohnRennie's comment another way, suppose the hole is obstructed by a circular stopper, held there by the weight of water above the hole. Then assume the sphere is trying to float but is tethered to the stopper. You want to know how much bouyancy it needs to just barely lift the stopper.
Apr 25	comment	Wind effect on driving a ground-based vehicle + for the wig :)
Apr 22	comment	Production vs. Collection, and Contaminants vs. Depositions, what might be missing in cold fusion research @user23467: If I were you, I would edit it in place, making it clean and to-the-point. I would also not beg any premise, such as "given X is impossible". Another course of action would be to delete the question, read everything you can find on the subject, and then maybe ask another question.
Apr 22	comment	Production vs. Collection, and Contaminants vs. Depositions, what might be missing in cold fusion research I think if Ron weren't burned out on this subject, he might point you to lenr-canr.org. The way I would say it is: It is correct to be skeptical of positive results. It is also correct to be skeptical of negative results. If something is not understood, it does not demand that you pick which side to "believe". At the same time, if the potential payoff is large, inquiry is certainly justified.
Apr 22	comment	Robot controling pouring process from a bottle @Slavisa: My point is, do you have a feedback loop? When I was in grad school 40 years ago, somebody programmed a robot to pour coffee in a cup by using a video camera connected to the computer. It could sense the rising liquid level and stop pouring at the right time. It's not much about physics, it's about heuristics and feedback.
Apr 22	comment	Robot controling pouring process from a bottle Is the robot working blind, or does it have any kind of sensors? My 4-year-old grandson loves pouring liquids, and he's a long way from caring about laminar inviscid flow, blah, blah...
Apr 20	comment	Physics behind the flow of gas coming out of a balloon @john1034: Float for a longer time? Do you mean it should stop ascending, or do you mean it should not burst? I'm only asking because balloons basically ascend until they burst. You could halt the ascent by letting out some of the gas.
Apr 18	comment	Conservation of momentum in two body collision @lily: the way to understand 2-body collisions is to look at the combined center of mass, which has a certain mass and velocity vector. It has the same mass and velocity vector after the collision as it had before. That's what conservation of momentum means. You take it from there.
Apr 16	comment	Concerning the curvature of an airfoil (shape) @l3win: I think you're basically right. The camber of the airfoil controls how much the flow can be diverted, and momentum flux generated, especially at low velocity and/or angle of attack, without stalling. Check here.
Apr 14	comment	Photon as the carrier of the electromagnetic force + Very nice. It might help if you could explain some terms unusual to us ignorencia, such as "cross section", "branching ratio", and "off mass shell". Thanks.
Apr 12	comment	Effective angle of attack of a wing Maybe you're saying this and maybe you're not, but when the yaw angle is zero, the wind "sees" just the chord slope of the wing. When the yaw angle is 90 degrees, the wind sees the dihedral angle of the upwind wing (and negative on the downwind wing). In between, it's in-between.
Apr 12	comment	Does a wing in a potential flow have lift? @Christoph: You're right. Thanks for pointing that out.
Apr 11	comment	Will this type of engine produce thrust? @Akash: No need to get carried away :) The J58-P4 engine of the SR-71 generated about 16 tons of thrust, but there's no mention of "plasma".
Apr 11	comment	Will this type of engine produce thrust? @Akash: In principle, though your heater would have to pump out as much heat as a gas flame if you want to get noticeable thrust.
Apr 10	comment	Make water droplets charged? + I think your mention of the Kelvin water dropper is right on target.
Apr 9	comment	Whats the anti-torque mechanism in horizontal take-off aircraft? @Jim: Lots of questions here about airplanes seem to arise because of not comprehending how heavy air is. In everyday experience, air seems ephemeral, but that's an illusion. It weighs about a $kg/m^3$ and even at low aircraft speeds it takes a lot of force to muscle it around. That force increases as speed squared, so it's practically as dense as water to a speedboat.
Apr 9	comment	Whats the anti-torque mechanism in horizontal take-off aircraft? It's just one of those things that pilots learn. Planes are usually designed with some built-in trim, to act as a compromise between different flight regimes, like takeoff (high power), cruise (medium power), and landing (low power). Like if you look at the rudder of a C172, you will see a little plastic tab near the bottom. That's a built-in trim tab so you need less right rudder on takeoff. As far as roll torque is concerned, the ailerons are plenty strong enough to manage it. It's not an issue.