> kaladorn@fox.nstn.ca wrote:
> ** Counter:
I don't know about that, huge GEVs will a require a hell of a lot of hop to
make it tactically viable, but you still are left dealing with very rough
sloped terrain as per Allan's point.
And regarding mines that would be an easy fix, to make mines effective against
GEV. In fact the standard US AntiTank mine (M21) alreay has a device that you
attach to the top to kill tanks that don't actually run them over with threads
but pass over the middle. It's a little stick that can be easily made to look
like any other weed. You bend over the stick and it detonates the mine sending
a plate charge right into the underside.
Instead of making things bigger I'd worry about making them smaller and
keeping the signature down. At technology most always we be more effective
pound or pound then tank technology. Wanna wast your money on bolos ofr
100 ton tanks? I'll put mine into shoulder or back-of-donkey fired
fusion
missiles, micro-nukes of other hyper-kinetic killing rounds.
> Allan wrote:
Chemical propellent is still pretty efficient. You launch a load into the air
and let gravity drop it where you want it. I think you'll always be able to
launch heavier warheads using chemical (or mass driver) propellent. In fact,
mass driver artillery may be a better bet for grav vehicles, particularly if
they are already using fusion power for the anti-grav units. Recoil
won't be a problem.
** Pardon? Unless you eject a counterbalancing projectile, you'll still have
recoil. The only time that might change (and this changes ALL the rules) is if
tech is advanced far enough to make intertial compensators for guns AND power
cheap enough in mass and cost to make this practical. Otherwise, and MDC gets
no better than a CPR gun (well, not much anyway) as a launcher. Newton still
applies.
> 3) Can we build a hovercraft that ways 80 tons, carries the kind of
You also have to ask yourself "why".
** I could. This was just my skepticism about Oerjan's thought that this could
be done.
What do you gain out of ground effect tank. Ground effect tanks are actually
not THAT useful, David Drake not withstanding. There is a very real limit to
the slope a GEV could scale, regardless of the slope's potential traction. You
raise the skirt too much and you lose lift. For that matter, you can't easily
tilt the vehicle. I think you could probably kill a GEV with deep, wide
trenches. True, that kills tracked AFVs too, but I'd imagine that narrower
trenches would have a nasty effect on
GEVs but allow tracked vehicles to pass. Likewise, anti-tank "dragon's
teeth" wouldn't need to be as big. This is just off the top of my head, too. I
sure wouldn't want to be infantry riding beside a GEV. You couldn't be that
close (due to the ground effect) and imagine standing beside one when it gets
hit in
the side with an anti-tank weapon. Ever play table air hockey? Imagine
you're an ant and the GEV is a puck! Nasty!
I think that tracked movement would still be more efficient. You don't have to
lift and propel the tank, just propel it forward. I think a tracked vehicle
would be able to move faster than a GEV given the same power plant. Of course,
ground pressure would be more of a problem in a tank, as the weight is spread
over a smaller area.
** Counter: 1) GEVs could have limited hop capability to pass over trenches
and some obstacles. They are less likely to set off mines (more distributed
weight, higher off the ground).
2) Speed - even with a set amount of max power for the vehicle, and a
GEV wasting a bunch for lift, it'd still potentially go faster for several
reasons. Low friction makes for efficient energy usage for travel. So the
power you do put in gives a much better return. Also, with a tracked vehicle,
you'll hit a limit of speed due to churning up the ground. The speed limit for
GEV, assuming the power is available, is higher and a product of aerodynamics.
With enough power, you can probably scale almost the same range of terrain a
track layer can. AND
cover lots of terrain it can't - rivers, lakes, areas of loose sand or
dirt or mud, landing zones, streams, defiles, trenches (with a hop, or with
some built up velocity), swamps. Many places conventional tracklayers get
stuck, it'd fly. It's fans are inside armour. Not so some of the spindles and
cogs on track layer systems.
3) GEV may well allow heavier armament. Why? Assume power is cheap and
plentiful (fusion/A-matter) - and fans can produce mucho lift by
advanced design - the limiter of tank weight then may become ground
pressure. You hit a point beyond which a tank will sink into the earth.
Because GEVs spread this weight, they can operate with a greater total mass
than a tracklayer unless the entire tank underbelly
is one big track - which probabaly has bad problem associated with it
in terms of complexity and manouvreability.
In the abscense of fusion power, the situation is different. And unless the
GEVs have fins and ducts, tracklayers will corner harder and faster. But the
GEVs should have the advantage in the long run sheerly because a GEV tank can
then double as a PBR and can operate in more terrain types. They may never
replace tracklayers, but then again... they just might. You'd be foolish as a
nation not to at least have them in your force to use as raiders and assault
units.
> 4) GEVs can move through swamps and if packing non-recoil weapons
That's about the only type of terrain where it has an advantage. Okay, mud and
snow would be advantageous.
** Mud. Mud = most places in spring or fall. Snow = most places in winter.
Both places track layers do badly.
But you still have that whole "slopes cause spilling of air out of the
curtain" problem.
** Sure. Powerful fans could push you up a slope even if you are heavy. This
whole argument of mine hinges on the presence of cheap efficient fusion. But
the GZGverse already presupposes that. So I'm not just inventing the idea.
> On Tue, 30 Nov 1999 13:56:15 -0500, kaladorn@fox.nstn.ca writes:
If I have anti-grav technology, I can make a perfect recoil adjuster.
Just make a gravity field in front of the vechical that will pull it with the
same force as the gun generates. Forces will cancel. This assumes pretty fine
control of the gravity fields as I need to make the field appear and disappear
pretty fast, and fine tune it some, but thats fine.
Also, the recoil from most tank guns just isn't that large compared to the
acceleration of an 80 ton tank.
Take a 1kg projectile, moving at 10000 km/hr (~9x the speed of sound).
That would push the 80,000 kg tank backwards at 0.125 km/hr. If the
round was 10kg, and we fired 10 of them a minute, it would still only
be 12.5 km/hr. If the tanks internal engines can't counteract that
much acceleration, they have a problem.
Its not just the speed of the GEV/Grav tank. Unless you are aiming the
weapon EXACTLY perpendicular to the ground, there is also an angular
(downward) force on the vehicle. Take your example (and assuming your math is
correct (as my mind is too fried to do the math right now).
If the vehicle is not grounded, your GEV/Grav tank has 10,000kg of
force that is torquing the vehicle (trying to make it rotate on axis), unless
its gun is aimed through the center of gravity (doubtful unless it is a fixed
weapon). Today's wheeled-tanks have a heavy suspension to counter act
this.
A GEV/Grav unit would have more problems, since the additional pressure
would be spread over a larger area (kinetic transfer by touch vs kinetic
transfer by pneumatic or gravitic means). If the vehicle grounds to fire, this
negates much of the advantage of
GEV/Grav units (i.e. the ability to operate in mud, snow, water, and
other soft terrain without getting stuck; and speed). While this cannot be
overcome, it indicates the added complexity of
GEV/Grav units. Also, you would not want to be infantry behind one when
it fires.
That having been said, I like GEV/Grav units. Given the cheap energy
that seems apparent in the GZG universe, they make sense for certain missions.
For soft terrain such as snow, mud, marsh, coastal areas, cultivated land
(not orchards), soft sand, etc. GEV/Grav make sense. Tread and wheeled
vehicles can get stuck easier. GEV/Grav would be especially useful in
amphibious assaults. For mountains and light woods (fruit orchards, edges of
forests) tread makes the most sense. It has the mass and power to push through
light trees and up broken slopes. GEV's have trouble of air leakage around the
skirt if
the angle is too steep. GEV/Grav units would have trouble generating
enough force to push through wooded areas. Also, tread has the advantage of
being the cheapest ways to carry heavy loads (tread spreads the ground
pressure over a larger area than wheeled and is much less expensive then
GEV/Grav).
For urban wheeled makes the most sense. They are easier on the highways,
usually lighter than treaded units (so bridges and sinkholes are less of a
problem), and often quicker on pavement than treaded units. Wheeled units are
also the least expensive option. For hard flat ground, all units work fine.
Grav units would seem to be a jack-of-all-trades. They can work in
most
terrains (even vacuum), they can do a pop-up attack (SG2), and they are
fast (DS2). But the big disadvantage would be cost. Using the DS2 construction
rules Grav units cost BIG! I would also think that they would be
hard/expensive to maintain. If away from the supply depot and something
breaks, it would be hard to jury-rig a solution. Also, it may require a
full maintaince bay to fix grav vehicles, where as other units may be able to
be fixed in the field.
Just some thoughts.
> On Tue, 30 Nov 1999 13:56:15 -0500, kaladorn@fox.nstn.ca wrote:
> ** Pardon? Unless you eject a counterbalancing projectile, you'll
As explained, you'll still have recoil. Just not a lot...
> ** Counter:
On the other hand a bouncing mine into those fan blades is going to cause a
mess. And as we've talked about elsewhere, "bouncing" isn't ground effect,
would require lift, and that isn't likely.
> 2) Speed -
Granted you have speed.
> AND
Yep, that too. Just hope you don't have hills and undulating terrain between
the lakes and swamps. *S*
> 3) GEV may well allow heavier armament.
That's something I hadn't considered.
Of course, there's still the hockey puck phenomenon any time the thing is hit
by a projectile (even a non penetrating one).
> In the abscense of fusion power, the situation is different. And
Except for hills and rough terrain. It would depend on the planet, but on
earth it wouldn't be much use outside of lakes, swamps, and deserts.
> ** Sure. Powerful fans could push you up a slope even if you are
But, as mentioned elsewhere, you have to have lift, not just ground effect, in
order to get it up a slope. Lift is probably not even possible in a fusion
world.
> But, as mentioned elsewhere, you have to have lift, not just
This reminds me of the famous Dalek cartoon, dalek at the bottom of a flight
of stairs saying 'Thats the end of world domination'
In the Slammers books the GEV's operate on rough terrain but this may be
wishful thinking. IIRC on full blow the tanks can lift a couple of feet and
they often ground the skirts during radical moves.
In 'The Warrior' Slick attacks from a hill top fire base and the tank gets
driven into several gullies but still keeps going, though I think the driver
is constrained by the terrain in the story. The thought of a 150 tonne hockey
puck running down a 1:6 slope doesn't sound that controllable even with fusion
powered fans.
In mountains you'd be pretty much stuck to the roads and ineffective as in
Afghanistan.
> ** Sure. Powerful fans could push you up a slope even if you are
Allan's right here. A hovercraft's lift fans (underskirt air pumps, really)
would actually be acting AGAINST the vehicle's travel up the
hill -
both because of the part of the lift vector effectively acting backwards when
the vehicle tilts, and because the fans will be acting to pull the
skirts at the front of the vehicle off the ground - thereby letting out
the air cushion OR requiring a huge increase in power from the lift fans to
compensate - which would have a corresponding increase in the rearward
portion of the lift vector which the pusher propellers would have to
overcome... It's a losing proposition - even with super fusion engines
with near unlimited power. You still won't get enough LIFT from the lift fans
(in the aerodynamic sense) 'cause of aerodynamic limitations to fly a
tank up a hill. Now, maybe if you have lift motors like the YAK38/42(?)
aircraft, or what the JSF concept has in mind, which are really powerful and
act only when the vehicle needs to go over something... Our GEV has
several super-high energy jet-type engines pointing downwards mounted in
the hull, which literally blast it over obstacles but keep off the rest of
the time to conserve fuel - these are reaction motors (ie a jet) not
"aerodynamic lift" propulsion fans (like a helocopter rotor or an airplane
propeller).... - so it doesn't rely on the "ground effect" at all for
clearing obstacles.
anyway, it's late (5am) and i'm fried... so off to bed:)
Later, gents.
> Los wrote:
> And regarding mines that would be an easy fix, to make mines effective
You also have induction fired AT mines (tank changes local magnetic field), IR
sensitive mines and trip wire (sort of) mines. The last two are commonly
placed on the side of a road, some of them actually fire an
IAVR. The Russians even developed an anti-helicopter mine, no doubt
based on the rotor's air displacement. GEVs anyone?
Thomas Barclay wrote in reply to Allan:
> launch heavier warheads using chemical (or mass driver) propellent.
In
> fact, mass driver artillery may be a better bet for grav vehicles,
....which you have, if you have grav propulsion at all.
> What do you gain out of ground effect
Imagine
> you're
Of
> course,
Considering that many modern AT mines have magnetic and acoustic sensors as
well as seismic ones, the lower pressure won't help you too much. Yes, the
hovercraft is (could be, at least) higher off the ground
than a tracked vehicle, but that'll only protect the crew - an AT mine
going off under it will cripple the skirts and/or fans, effectively
M-killing it.
> 2) Speed - even with a set amount of max power for the vehicle, and a
Low ground friction also less efficient accelleration and wider turn
arcs. High speed, low maneuverability - particularly if you put heavy
armour on the vehicle.
I think you're overestimating the importance of fusion power, too. A
bit like having a miniature nuclear reactor powering your tanks IMO :-/
Regards,
On Thu, 2 Dec 1999 08:43:21 -0000, "Tim Jones"
<Tim.Jones@Smallworld.co.uk> wrote:
> In 'The Warrior' Slick attacks from a
Well, someone mentioned that Gibson wasn't much of a technologist. Neither is
Drake. *L* The books are fun, but he should have used anti-grav instead
of ground effect.
In a message dated 12/2/99 4:43:52 PM Eastern Standard Time,
> oerjan.ohlson@telia.com writes:
> I think you're overestimating the importance of fusion power, too. A
Darn--and I've been designing all those FGP tracked vehicles, too! Oh
well, I guess it's back to the old drawing board......NOT. I actually use the
FGP's in some designs because of supply reasons (not everyplace will have a
plentiful supply of petrochems, but water is
pretty abundant).
Seriously, I do not think that you can easily overestimate the effect that
small, pwerful, portable fusion plants would have on vehicle (and weapon)
design and tactics, logistics, and just about everything else. Going out on a
limb, I would say that comparing CFE armies to FGP would be like
horse-and-buggy vs WW2 motorized. Not a great analogy, but something
like that anyway.
Rob
Rob
> Rob Rob wrote:
> > I think you're overestimating the importance of fusion power, too.
A
> > bit like having a miniature nuclear reactor powering your tanks
> Seriously, I do not think that you can easily overestimate the effect
Thomas seemed to say that the fusion reactor is compulsory for the kind of GEV
units he envisions. *That* is where I think he overestimates its
importance - there are other small, nearly as powerful power plants
that aren't nearly as nasty if they get hit... and sooner or later they *will*
get hit.
Yes, fusion is very nice - at least if you have a heavy water plant or
similar to manufacture the deuterium and tritium you need to fuel the
FGPs. Hydrogen on its own doesn't fuse very well at all :-(
Regards,