Steven Owens [email removed] writes:
> I was speaking of a slow, "single-shot" laser, i.e. pulse, wait
> one second, pulse, etc. A fast-pulsing laser would be functionally
> equivalent to a beam laser in terms of beam continuity, targeting, etc.
Right. Such a laser probably has a targetting mode where it fires more
rapidly at a *MUCH* lower energy. This could be built into many types of
"single-shot" pulse lasers at not much additional cost; in others it could
be supplied by a cheap solid-state continous wave or rapid-pulse laser as a
targetting device.
> Actually, I've played paintball in such surroundings. Photon
> doesn't do much for me. I just deleted about a paragraph's worth of
> ranting about how horrible photon is. This isn't the place. I've
> played paintball in one of the best indoor fields I've ever seen - it
> used to be a state mental hospital. Three floors, hallways, rooms,
> windows, stair wells, roofs, etc. Tons o' fun. Several games we
> played with LZ-marker smoke flares to provide an interesting
> environment.
That sounds interesting; as far as I know, there are very few paintball
places around here, and no indoor ones. Photon is, however, a relatively
popular trip for our Explorer Post (I am an assistant advisor for EP250) so
I get to go about as often as we can afford to. The scouts are interested
in paintball, so if you could give me any pointers towards a nearby,
affordable place (affordable to the average suburban teenager with no
accumulated equipment), I would be grateful.
Photon has quite a number of problems; every once and a while someone talks
about coming up with a competing game that fixes most or all of them. The
ones that bug me the most are the helmets, the lack of visual effects, and
the frequent delay in the audio feedback. Although I haven't played in many
different arenas, the size and layout makes quite a difference; I suspect
that the Baltimore Arena is about as small as is practical. I do know that
I didn't enjoy the only smaller one I have played in.
> >*Embarrassed blush* I am and have been for a long time a pretty good pistol
> >shot, but I made a complete fool of myself in the Naperville Photon Arena.
> >Shooting and being shot at are two very different things, and it takes a
> >long time to develop reflexes (and a lot of money, too).
True, and marksmanship doesn't count for much in Photon; the gun has an
acceptance angle wider than a 12 gauge's shot pattern. And at least in the
Baltimore Arena, the things have no sights worth mentioning.
Seth the Lesser [email removed] writes:
> On the other hand, keep in mind that the forward acceleration of 1G for a
> Type A doesn't translate to 1G of *lateral* acceleration; thrusters only get
> 40% of normal efficiency parallel to the plates, so that's only 0.4G lateral
> acceleration. You'd know better than I would, but isn't lateral
> acceleration more closely related to maneuverability and "crankiness" than
> forward acceleration is? 0.4G is an *awful* lot less than the 9G that you
> say an F-15 can pull in a tight turn.
Keep in mind that the thrusters can be overdriven by at least 500% for short
periods of time (short in a space combat time scale; this could be as long
as several minutes). For our hypothetical 1g trader, this means a 2g
lateral accelleration, and a 5g forward sprint. For a 6g combat craft, this
means a 12g lateral accelleration, and a 30g (!) sprint; such a craft would
be more limited by the intertial compensator's ability to keep the pilot
from being mashed into goo than anything else. Presumably the compensator
is a gravitic device, and can be overdriven like the drives can. I also
assume that overloading the drives and compensator like this consumes large
amounts of power.
In my opinion, this ability is the basis for the agility measure of a
spacecraft. A craft with no additional power available to overdrive its
thrusters and compensator has no agility; its ability to make rapid, drastic
changes in its position and vector are extremely limited. When additional
power is available, a ship has agility: in the case of a 6g combat ship, 100
seconds of 30g accelleration means a displacement of 150km (and a velocity
vector change of 3km/s)!
With respect to agility, I don't follow the standard MegaTraveller rules.
Instead I use my own: Agility is limited to the maneuver drive rating (ie:
a ship with Maneuver=1 has a maximum of Agility=1). Emergency Agility is
computed based on the assumption that all available power from weapons and
screens is routed to the drives. For merchants, auxiliaries, and other
underpowered designs, this usually results in an emergency agility no better
than their normal agility. Emergency agility is also limited to the
maneuver drive rating. Finally, for ships with a large proportion of cargo,
stores or fuel, agility may be computed for different configurations, as the
mass of the vessel changes. These are handled on a case-by-case basis.
When maneuvering in space, there is no reason why the spaceship has to keep
its nose pointed along its current velocity vector; this is in sharp
contrast to an aircraft. The most efficient means of turning is to point
the main drive in the right direction and blast away.
In the description below, the "nose" of the craft is at the front of the
roll axis, which is also the thrust axis of the main drive. The yaw axis
points up and down (up defined relative to the pilot) at a 90 degree angle
to the roll axis. The pitch axis points port and starboard, (also defined
relative to the pilot) at a 90 degree angle to the roll and yaw axes.
Probably most pilots would start a turn by rolling the craft into the plane
of the turn (so that the yaw axis points to the center of the turn) and
pitching up. As the ship passes its intended vector heading, the main drive
is run up to the desired thrust. Pitch-up continues, sometimes up to 180
degrees as the main drive is used to change the ship's velocity vector.
As the velocity vector approaches the desired heading, the pilot pitches the
craft down, towards the new heading, possibly decreasing the main drive
thrust to the desired cruise output. Delicate adjustments can be made to
the final vector by using pitch and yaw. Precise piloting would establish
the new vector without overshooting or yaw corrections, and would leave the
ship with its nose pointed along the new velocity vector.
From this position, the main drive could be used to accellerate the ship
along its new course; a simple 180-degree pitch or yaw maneuver will allow
the ship to "swap ends" and decellerate, or another turn can be started. In
some situations, "barbecue mode" may be desirable. This is where the ship
is placed in a continous slow roll; this may be done to allow sensors or
weapons to sweep through 360 degrees, or to equalize thermal effects, or to
mimic gravity. If "barbecue mode" is started, the roll will have to be
stopped before any course changes.
In an atmosphere, a spacecraft's performance will be affected by its hull
streamlining (or lack thereof). Way back in the early days of Classic
Traveller, Paranoia Press published the Serpent Class Scout/Courier. One of
the interesting features of this ship was variable-geometry (swing-wing)
wing and tail surfaces. I have always assumed that an "AF" (airframe) hull
implies aerodynamic lifting and control surfaces of some type; such craft
would all be able to use wing lift to help them turn. They may be variable
geometry like the Serpent Class, or lifting bodies, or relatively
conventional airframes like the current Space Shuttle.
There is no reason that winged spacecraft and grav vehicles operating inside
an atmosphere could not maneuver using wing lift. Vehicles without wings,
in particular many spacecraft and grav vehicles would have to use engine
thrust to perform the turns. Grav vehicles would have their grav plates
oriented so that the primary axis of thrust is down or at an angle down and
aft (so that the vertical component provides the lift to keep the craft
airbourne, and the horizontal component maintains level cruising speed).
Such craft could turn the same way aircraft do, by banking into the turn and
increasing their grav module's output.
The thruster plates on a spacecraft are probably oriented based on a
compromise between atmospheric operations (flight in a world's atmosphere
and scooping operations on a gas giant) and convenient take-off and landing
operations, and convenient deep space operations. Ships for which
atmospheric operations are the most important part of their mission
(including world interface and fuel shuttles, fighters which have an
atmospheric mission, or vessels which are expected to frequently scoop for
fuel) will probably have AF hulls, with aerodynamic lifting surfaces and
flight controls, and thruster plates oriented along their line of flight.
Most other types of ships which are intended to land on a world would use
type SL hulls, and have their thruster plates aligned to provide thrust
perpendicular to their decks and landing gear (so that the thrusters provide
the most thrust as "lift" in atmospheric flight). This also allows ships
to land and taxi comfortably with their decks level. When maneuvering in
space, flight attitude is mostly irrellevant.
Unstreamlined craft (type USL) are not intended to in an atmosphere at all;
I typically rule that except for planetoids (which may not land on a world
at all), they may operate in an atmosphere as long as their speed is kept
below 120kps. Thruster plates on these designs are typically oriented for
maximum convenience; if regular landings are anticipated the thrusters will
be providing "lift" for flight, so the landing gear, decks, and access will
be aligned accordingly.
Bertil Jonell [email removed] writes:
> So while a good scout ship (2G) should be able to outclimb almost anything
> TL8 or less (except SAM's:) almost anything including a WWI fighter should
> be able to outturn the scout ship.
Allowing the scoutship's thrusters to be overdriven by 500% for short
periods of time, my agility modification would allow a Maneuver=2, Agility=2
ship to pull up to 10g for short periods of time (however, again using my
modification, the most a typical scoutship of Maneuver=2, Agility=0 ship
could manage is 2g). Airframe hulls would be able to contribute some wing
(or body) lift to the turn, too.
[email removed] (Steve Hunter) writes:
> I may be utterly wrong, be 1G acceleration on modern day
> military aircraft would surely be common (or even exceeded) .. if
> they are structurally capable of 9G turns, and commonly do 4-6G
> turns ..... can anyone tell me for sure?
The engine thrust to weight ratio for modern combat aircraft can slightly
exceed 1:1 (or about 1g of accelleration) for high-performance jets at full
thrust (usually this means with the afterburners lit) with moderate loads
(air-to-air missiles and fuel only). Planes in this category include the
F-15 Eagle, F-16 Fighting Falcon, all models of the Harrier, the French
Mirage 2000, and the Russian Yak-36mp Forger (and possibly the MiG-21/bis
Fishbed). Most other aircraft have a much lower thrust to weight ratio;
these aircraft weight many times more than their engine thrust.
The Harrier and the Forger are unique in that they have rotatable nozzles to
direct the engine thrust downwards, so that they can take off and land
vertically; they are sometimes called "jump-jets", V/STOL (Vertical or Short
Take-Off and Landing) or STOVL (Short Take-Off and Vertical Landing)
aircraft.
When an aircraft turns, it uses its wings, not its engine, to alter its
flight path. The airplane banks into the turn, and the lift from the wings
provides the force which turns the aircraft. A modern combat jet can
generate lift forces up to nine times the aircraft's weight. This force
does not come without cost, however; producing this lift also causes drag
which slows the aircraft down, and increases its minimum (stall) speed. The
following table may help, it shows stall speed in knots (nautical miles per
hour), angle of bank in degrees, and g load for a hypothetical aircraft:
Stall Speed: 120 170 208 240 268 294 317 339 360
Angle of Bank: level 60.0 70.6 75.5 78.5 80.4 81.8 82.8 83.6
G Load: 1 2 3 4 5 6 7 8 9
Nine g is about the practical limit for human pilots in g-suits (at least
until someone invents the intertial compensator); therefore manned aircraft
are rarely stressed for higher loads than this (research aircraft are an
exception, I believe that the Bell X-1 was stressed for up to 12g in either
direction). Missiles and drone aircraft can also exceed the 9g "limit"
quite easily.
A spacecraft maneuvering in outside the atmosphere is a whole different ball
of wax; there is no air, no lift - no aerodynamic forces whatsoever. Any
forces which act on a ship have to come from the ship's engines. There are
similarities, because both an aircraft and a spacecraft need to be able to
control their motion in all three dimensions.
Scott Kellogg, please correct me if I made any horrible errors in the above;
I'm not a pilot, just a pilot-wanna-be, simulations programmer, and gamer!
> we may have something more like options on a computer
> console (it would be quite complex to maneuver a large bulk in zero-g)
I don't think so. There is nothing inherently more difficult about
maneuvering any large mass in zero-g than maneuvering the same large mass
here on Earth. The required judgement and reflexes will be *DIFFERENT* but
not impossible to learn nor out of the scope of human abilities.
In many ways this sounds like the quest for "inherent stability" which
several early heavier-than-air flight experimenters got hung up on.
Stabilizing a moving vehicle in three dimensions was considered so difficult
as to be beyond human ability; therefore any such aircraft would have to be
inherently stable under any flight condition without human control input.
All of our space-flight experience to date has shown that human judgement
and skill is up to the task of flying spacecraft; I don't see why larger
spacecraft and higher technology should change this.
Finally, direct human control is exciting and involving from a story-telling
point of view. And since we are, in the end, telling stories and not
predicting the future, this is the final and most important criteria. In my
opinion it is simply more exciting have a pilot fly the starship with some
type of flight controls. It is draws the players more into the game and
their characters to say "the ship is overloaded; you wrestle with the
controls and it responds sluggishly" than to say "the computer informs you
that docking will be delayed because the ship is overloaded".
[email removed]
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Science-Fiction Adventure
in the Far Future