Recent content by Speed

Russ, my post was factual and dispassionate. Read Clausius' posts and decide if that is the case for him. Do think again about who should "cut it out". I will not have my name sullied just so that a certain poster's feelings don't get hurt. As for your comment about variations in g, the...

Structural issues aside, pumps and space elevators are among the most efficient methods of getting mass to orbit on a W/kg basis. Clausius, you forgot to account for a variation in g. Your equation is also missing a few constants. Also your assumptions are inconsistent with your...

The suggestion is not new. However the problem with pumping air through pores in the wing is that large amounts of complex ducting and pumps will be required. Space in the wing normally reserved for fuel tanks will also need to be cut down.

Shear stress opposes relative motion in the fluid. Tau = shear stress; mu = viscosity; v = velocity; z = thickness of layer. Hope this helps.

You were given the kinematic viscosity, you need the simple viscosity, which is the kinematic viscosity multiplied by the density. The shear shress equation is based on the definition of shear stress for a Newtonian fluid. Tau = mu*v/z

Viscosity = 256.94 Pas Friction due to shear stress, F = 102776v Cube mass, m = 21.6kg m g (1 - Sin \theta) = 102776v v = 4.0988ms-1

You need to determine how the drag varies with speed. Then for a first approximation, you relate that to the power output of your engines: P = \frac{1}{2} \rho v^3 LW Cd Bear in mind that your drag coefficient would have to include viscous, wave and profile drag terms.

I remember reading an article a while back that bookies & betting houses are the best predictors of the future we humans have. This article came out about the time of the US election, and stated that bookies have rarely if ever predicted the outcome of the US elections wrong, and for Bush's...

No, the whole point is that bending and torsion are coupled here. Even if you do not apply a torsional load to the beam, because of the coupling if you bend it, it will twist. Likewise if you twist it, it will bend. Only in very special cases are bending and torsion not coupled. Often...

It is not so straightforward for J-beams. The bending deflection of J-beams is coupled with the torsional deflection, in all but the most special loading (via shear centre) case. You will need to pick up a structural mechanics book, I'm afraid, because it is not easy to explain how to do the...

Unfortunately, the more turbulent the airflow over a cooling surface, the better the heat transfer rates from the surface. There are several methods of precipitating turbulent flow; but the most popular for cooling systems is just a more powerful fan, because it kills two birds with one stone by...

Thanks for your answers all. What I am trying to ask is how evolution produces large changes in a population, where the individuals would be mostly similar to each other. I know some posters have commented on the implausibility of an "evolutionary goal" - however for the sake of this discussion...

Suppose it turns out that humans with a set of eyes behind their head, or humans with 2 pairs of hands were better than current morphologies. How would evolution even begin to evolve humans with such features? We don't have any mutations that can produce something remotely close to a second...

Can we see the full question?

The density or weight of the metals won't be much of an issue if you mine them on site. It is however true that denser metals offer better protection against radiation than lighter ones like Al or Ti.