I don't want to be seen to be interefering in a argument but at what point
does a hovertank stop been a tank and start been a ship.
It's called the Zubr and its better armed than some warships (not suprisingly
since thats what it is)
foxxaero.homestead.com/indrad_068.html
It is quite feasible to build a hovertank. It's just that it would NOT
look like a land bound MBT but more like a HOVERCRAFT/WARSHIP.
> Adrian wrote:
> I don't want to be seen to be interefering in a argument but at what
When it grows too big to move down a normal highway without knocking down the
lightposts on both sides at the same time? <g> Tanks are primarily *land*
vehicles, after all...
> It's called the Zubr and its better armed than some warships (not
The Zubr isn't a "tank"; it is a landing craft capable of carrying an
(understrength) tank platoon. At 57.3m long and 25.6m wide it is roughly
the size of an OGRE... but without the OGRE's heavy armour and armament.
Later,
If you didn't care about floating on water (as most MBT's don't) then you can
have larger ground pressures and a more compact footprint. But as you shrink
the footprint and increase the ground pressure, you need more power to stay
aloft until you reach something like a Harrier which can be held aloft on pure
thrust. You reach a ciritical point as more powerful power plants require more
space and weight in general, so
unless there is a breakthrough in power/weight ratio for power plants
there is a limit to how much thrust (airflow) you can generate.
Zubr vs. M1 Abrams
For example - M1 Abrams MBT - ground pressure = 13.50 PSI (pounds per
square inch), size is 26 feet long, 12 feet wide.
The tracks are substantially narrower than the full width of the tank.
Average person = ~3 PSI
The Zubr has dimensions of 57.3m of length and 25.6 meters of beam for 1466.88
m2 of area. It is listed with a displacement of 555 metric
tons, which gives a surface pressure of 1223565 lbs /2272304 in sq. =
0.538 PSI. If you were willing to let it reach the ground pressure of an MBT,
the dimensions would shrink to a 30 foot x 21 foot (roughly 9.5 meters x 6.5
meters) footprint. Think of packing 555 tons onto the footprint of two large
trailers.
Slammer's tanks are described as 170 tons and have roughly a 9m x 4m
footprint and so would be roughly 1/3 the weight on 2/3 the area of a
compacted Zubr and fall about 6-7 PSI. The overall dimensions are
roughly the same as an M1 Abrams but is 3 times heavier but has a ground
pressure of only half that of the M1.
So the answer is future hover tanks can look like tanks. The reason they look
like ships today is the requirement that they float above
water, which requires a very low ground/water pressure to achieve. If
you don't worry about trying to float on water, you can have a very
dense/compact vehicle similar to a modern MBT.
--Binhan
________________________________
From: owner-gzg-l@lists.CSUA.Berkeley.EDU
[mailto:owner-gzg-l@lists.CSUA.Berkeley.EDU] On Behalf Of Adrian
Sent: Wednesday, May 25, 2005 1:21 PM
To: gzg-l@csua.berkeley.edu
Subject: Hover tanks
I don't want to be seen to be interefering in a argument but at what point
does a hovertank stop been a tank and start been a ship.
It's called the Zubr and its better armed than some warships (not suprisingly
since thats what it is)
foxxaero.homestead.com/indrad_068.html
It is quite feasible to build a hovertank. It's just that it would NOT
look like a land bound MBT but more like a HOVERCRAFT/WARSHIP.
> On Wed, May 25, 2005 at 03:42:04PM -0600, B Lin wrote:
Well, yes. Part of the problem with this argument is that hovertanks
really don't make sense _unless_ you regularly have to sprint at high
speed and/or cross substantial open water, and can make them light
enough to do that; for any given output from your power plant, you can connect
it to a conventional track drive mechanism and get much more armour into a
more compact chassis at the price of going rather more slowly.
(Hammers' Slammers basically ignore this by having practically infinite power
output, very lightweight armour technology, and terrain that's
peculiarly well-suited to hovercraft.)
R
Actually, I don't think that HS has "lightweight" armour technology as Iridium
and Osmium are the two densest metals known. The hulls and turrets of HS tanks
are cast Iridium and since the size is roughly 9 meters by 4 meters for the
hull, it is a rather heavy object. Also the listed weight for a HS tank is 170
tonnes, roughly 3 times what an Abrams weighs for roughly the same dimensions.
An Abrams has a 1500HP turbine engine (21HP/ton). VTOL aircraft and
helicopters have dramatically higher power requirements - for instance
the CH-54 Skycrane with a max weight of 21 tons has two Pratt & Whitney
JFTD12-4A, 4500 HP engines (about 428 HP/ton).
The Harrier with 13 tons max weight has a Pegasus engine capable of 21,000 lbs
of thrust (note that the Harrier can not take off vertically when fully loaded
as the thrust to weight ratio is not greater than 1 to
1.)
The LCAC (Landing Craft, Air Cushion)for the US Marines uses 4 turbine engines
producing 12,280 BHP for a craft that is 200 tons full load (61
HP/ton). The footprint of an LCAC is 88 feet x 47 feet, roughly 8 times
the size of an M1 Abrams, but only 3 times the weight.
Inferring that a smaller footprint requires more power to maintain a vehicle
off the ground, to get something like a HS tank off the ground using the
stated footprint would probably require something closer to
the power/weight ratio of a helicopter (428 HP/ton) or about 72,760 HP
of engine power or 340,000 lbs of thrust to go purely VTOL.
For reference, a PTG10 Gas turbine from GE has an output of 15,000 BHP and the
dimensions of 30' x 8' x 13' and weighs 32 tons. And the
Rolls-Royce Trent 900 engine which powers the Airbus 380 generates
70,000 lbs static thrust and has a fan blade diameter of 112 inches (almost 10
feet).
The ability to generate a huge amount power in a compact enough space will
essentially require fusion plants or some equivalent to make hover tanks
practical, as fuel and space requirements are a major stumbling block. For
example the LCAC has a fuel capacity of 5000 gallons. It burns 1000 gallons an
hour to run its engines.
--Binhan
[quoted original message omitted]