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Link to thread of next article. Re: NASA Looks Toward Visionary Interstellar Travel. Date: 1997/12/09
In article <348CA74F.3FBC6B95@interaccess.com> Paul Dietz <dietz@interaccess.com> writes: > ale2 wrote: > > > > We might rent the Concord, it has those nice long landing gear so the > > plane's belly sits high off the ground. Lots of room for a rocket or > > rocket plane. > > Not enough payload, I think, and I doubt it's going to be able > to achieve anywhere near its current top speed with a booster > hanging off the bottom.
I have an old book "The Encyclopedia of Aviation and Space Sciences" aimed at young minds. They have the specifications for the Concord:
(to guess the fuel load take 376 - 162 - 28 =186,000 lbs)
and some other facts about its flight
If the Concord were built of titanium it would be capable of Mach 2.7.
Assume a fuel payload of 186,000 lbs. and assume that 1/3 (i could be way off here) of it is used to get to maximum altitude, drop rocket, and get back home. That would mean that a usable payload of about 124,000 + 28,000 lbs or 152,000 lbs of rocket lifting capacity. Reduce this number by say 25% (big guess) because of reduced performance because of the rocket drag, but you still have 114,000 lbs of rocket payload, not shabby.
As for reduced speed, let the rocket account for 25% extra drag. As the drag force goes as v^2 we can approximate the reduced speed with the rocket using the given top speed of Mach 2.2 and the 25% approximation above.
Thrust = constant times (v_1)^2 = 5/4 times constant times (v_2)^2
v_1 = Mach 2.2 --> v_2 = Mach 1.96 still not shabby, and if one can kick in the afterburners we might recover or boost the cruise speed of Mach 2.2.
> > Do modern fighter aircraft get below Mach 1 before firing rockets or > > dropping bombs? > > Getting ordnance to separate cleanly at high speed is a > serious problem. Rockets solve the problem by brute force. > With bombs, you want to release subsonic, I think, to get > reasonable accuracy.
I don't think this is a big problem, bet you a 6-pack. So we will drop some dummy rockets from the Concord and pay the pilot hazard pay. Would not cost much to try.
> > > Or maybe it's because of the poor performance and > > > economics of solids, vs. ground-launched liquids?
As Jim said, I'm not sure what you are trying to say here.
RRe: Trinary Addition - Is it possible. Date: 1997/12/13
In article <66s15m$o8k$1@agate.berkeley.edu> Nicolaas Vroom <nicvroom@innet.be> writes:
> An Analog Computer works instantaneous compared with a Digital Computer > (assuming there is only one arithmetic unit) which works sequentially. > A third type of computer is a Hybrid Computer (a combination of both) > which was (?) very often used for flight simulators.
Anyone know if it is possible (and advantageous) to use an analog computer to do some form of lattice QED or QCD simulation?
Re: Trinary Addition - Is it possible. Date: 1997/12/19
In article <66vp3q$9in$1@cnn.Princeton.EDU> shocklee@rogue.Princeton.EDU (Paul D. Shocklee) writes:
> ale2 (ale2@psu.edu) wrote: > > : Anyone know if it is possible (and advantageous) to use an analog > : computer to do some form of lattice QED or QCD simulation? ... >To model a quantum field > theory like QED or QCD, one would need the circuit elements to incorporate > quantum effects in a non-trivial way.
Well I'm encouraged, at least you did not say it was impossible!
&Tinker Toy spin. Date: 1997/12/16
I call the function TTS = exp[-iwt] exp[-iNf/2] (here f is the cylindrical coordinate phi) my Tinker Toy Spin. If one sets TTS equal to some complex constant C of unit magnitude one can get the pretty graph of a helicoid (plot those points x, y, and t (suppress z) that satisfy TTS = C).
With a rudimentary knowledge of relativistic transformations one can figure out what this function looks like in different relativistic frames.
There are some pretty interesting transformations one can apply to TTS. Freeze time and take a region of the space part of this function which includes a piece of the z axis and bend that piece of the z axis into a loop or any other closed curve with the possible addition of a twist. Now continue this new function into all space in some minimal way.
&Something Feynman Wrote. Date: 1997/12/16 (likeness of Feynman by my daughter)
After summing up the rudiments of quantum mechanics Feynman tries to answer a question that readers might have at this point of his book (page 1-10, Vol III Feynman Lectures on Physics) . He writes,
"One might still like to ask: "How does it work? What is the machinery behind the law?" No one has found any machinery behind the law. No one can "explain" any more than we have just "explained". No one will give you any deeper representation of the situation. We have no ideas about a more basic mechanism from which these results can be deduced. ... And no one has figured a way out of this puzzle. So at the present time we must limit ourselves to computing probabilities. We say "at the present time," but we suspect very strongly that it is something that will be with us forever--that it is impossible to beat that puzzle--that this is the way nature really is."
Like someone who believes in a God never seen I also have faith that there exists an explanation which answers the question, "how does it work". Further, if someone of good science background could read all possible one page compositions (about 10E800), composed using only words from a medium sized dictionary, then one would know "how does it work".
&Further Questions. Date: 1997/12/16
1. If one were to focus on a simple quantum mechanical phenomena, say an electron scattering off a crystal, one might think, how many different ways can such a process be described such that quantum mechanics is implied? How complicated can it be?
2. We soon learn that the wave function for a localized particle is made by superposing a large number of plane waves. Almost magically this addition of waves gives a function that is zero almost everywhere and finite in some small region. I have wondered for some time if there is something going on in those regions where the wave function is practically zero?
Link to thread of next article. &A weak argument for neutrino mass. Date: 1997/12/16
The question of neutrino mass has been in and out of the news for years and my hunch is that neutrinos have mass just as the other fundamental fermions do. My hunch rests on the following observation that for a given family the heaviest particles are the ones which interact with the largest number of forces. Consider the first family of quarks and leptons. The up and down quarks are most massive and interact via four forces. The electron is next massive and interacts via three forces. Following the pattern (granted, not much of a pattern) the neutrino, interacting via only two forces, will be the least massive particle.
&Elastodynamics Compared With Electrodynamics. Date: 1997/12/16
The equations of linear elastodynamics (in this case for an isotropic, homogeneous elastic body) are close to those of classical electrodynamics. Compare ,
In (3) m and l are constants, r is the mass density, u is the displacement field, and F is the body force density. The symmetry is also spoiled somewhat because in solids the transverse wave speed and the longitudinal wave speed are different.
One can compare many phenomenon in electrodynamics with similar ones in elastodynamics, for example, a transverse electromagnetic wave with a transverse wave in an elastic solid. Let the vector potential A be compared to the displacement field u then the partial time derivative of u, u,t is likened to the electric field E and the curl of u is likened to the magnetic field B.
If one could grab and shake a single point of an infinite elastic solid one would get a displacement field u nearly identical to the vector potential A of the analogous situation, a short oscillating dipole (at least for the far field).
Unfortunately the comparison of electrodynamics and elastodynamics starts to breakdown when we try to consider relativistic or gauge transformations of Am as compared with u.
&Electrons, Photons, and the Pendulum. Date: 1997/12/16
In image has formed when I think of the electron and photon fields which I neither improve upon or part with for now. It goes something like this, take a piece of space and triangulate it. At each vertex place a system such as a physical pendulum. Let the potential energy of the pendulum at the ith vertex go as -cos(qi) (q i measures the angular displacement of the ith pendulum from some reference point). Let each edge of the triangulation be a coupling between the two vertices associated with it (remember there is a pendulum at each vertex). Let the form of coupling go as asin(qj - qi) where a is some small negative number and q j and q i are the coordinates of the pendulums at the vertices of this edge.
Now such a system will have three fundamentally different modes of motion which are exhibited by a single physical pendulum,
The basic idea being that charge and the electromagnetic field are somehow different modes of some underlying "stuff". I suspect that if superstring theory is correct something like the above will be made clear.
&Fun With Capacitors and Inductors, Massive and Massless Fields. Date: 1997/12/16
In a great book* the physics of the anchored string is considered. This system is interesting because it has the same dispersion curve as that of a massive quantum. Also interesting is that depending on which plane the string vibrates in one can also have massless modes. A single system with both massive and massless modes, like spacetime?
With a simple combination of inductors and capacitors one can produce electrical systems with both massless and massive modes. In the following L = inductor, C' and C are capacitors. Also the systems are meant to continue tothe left and the right for some distance. If one wants the ends of thesystem can be connected together. Wow** see below. These systems can then be coupled into 2 dimensional arrays. And so on
into systems of higher effective dimension **(Consider a 3 dimensional array of such massless or massive systems that forms a large cube. Identify loose ends in the following manner:
top side identified to left side, right side identified to front side, back identified with bottom. One would have interesting modes where a "plane" wave pulse would travel up then right then back then up and repeat).
The massive and massless systems can be coupled in many ways, for example let the mutual inductance between the ith inductor of each system be given by some function of time t, M_i(t). A possibly interesting form of M_i(t) would be to make it a step function between the values 0 and 1, with the times that M_i(t) = 1 random and of short duration. It is interesting to consider how the system would evolve for different initial conditions assuming all elements to be loss-less.
*Vibrations and Waves in Physics, by Iain G Main, 3rd edition.
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