Re: Trailers

Barclay, Tom wrote:

> Oerjan said:
> 
>>The grav trailer needs its own near-full-sized grav engine. Simply
>>providing the lifting force isn't enough; it also needs the
>>side-to-side maneuvering capability as well or it'll whip out in
every curve
>>the main vehicle makes (imagine driving with a loaded trailer on
smooth >>ice, with smooth tyres... then remove the ground friction :-/
). 
> 
>==> I concur, though you may find because you're hauling it behind, if
you
>were going at speed, drag would possibly keep is straight behind you
>(think dragging a glider behind a plane). 

If you go *straight ahead* at speed, the trailer will stay straight
behind you thanks to air drag. If you brake, or turn, it won't stay
there any more than a glider will stay straight behind a towing plane
which slows down or turns. (Which is to say "not at all" even at
supersonic speeds, unless the glider also has a full set of maneuvering
surfaces *and* either a pilot of its own or is remote controlled from
the towing plane.)

>>The only thing which keeps a usable grav trailer from being a
straight-up
>>robotic vehicle is that it'd take its maneuvering commands from the
>>main vehicle instead of from an on-board computer brain. GEV trailers
>>have exactly the same problem.
> 
>==> Well, yes and you don't need to wire big perceptual brains into
them
>either...

Modern UAVs and cruise missiles don't have big perceptual brains
either, but they're quite capable of following routes determined by
someone else. They do, however, need full-sized propulsion and
maneuvering systems.

 >>Maybe the AG unit (or GEV) unit in the trailer is powered by some
>>sort of electrical PTO from the main vehicle 
> 
>That assumes a *seriously* over-sized powerplant on the main vehicle,
>though. Very unlikely, unless the main vehicle is purpose-built for
>towing grav/GEV trailers.
> 
> ==> Unlike modern military wheeled tow vehicles? 

You mean that modern military wheeled tow vehicles are *not*
purpose-built for towing trailers? (OK, they're purpose-built to tow
anything that needs towing, not just trailers...) 

>Have you noticed many of them have an awful lot of  overpower to tow
>heavy trailers... 

John's original post allowed *all* vehicles to tow trailers...
including MBTs and SPGs. No, I haven't noticed any awful lot of
overpowering on MBTs or SPGs; in fact most tankers and artillerists
I've talked to complain that their vehicles are *under*powered.

>and they've got to drag them versus friction on the surface (yes
wheels >aren't too bad... but an air puck has to be better). So if the
lift energy can >be supplied, the energy to pull might be less. 

1) Unless you're going extremely fast, the energy required to lift the
thing is very much larger than the energy required to move it
horisontally. We're talking multiple orders of magnitude of difference
here.

2) An air puck requires less energy than a wheeled vehicle to start
moving at all, but it requires a lot *more* energy when you want it to
*stop* moving as well as when you want it to start moving in a
different direction from where it is currently going because you don't
have any ground friction to help out. In FT terms, the wheeled vehicle
uses Cinematic movement while the grav floater uses Vector movement :-/

>==> And if you are towing it behind something with the same kind of
>powerplant that can lift a 250 metric ton main battle tank (aligned
>crystaliron armour, a 200 gigawatt pulse laser, a GMS, and multiple
>smaller armaments, plus an ECM suite) but which has no armour (ie a
>grav truck or tractor) or which only has minimal armour and some
>engineers aboard (CEV), this seems quite believable to me.

See above. John's original proposal allowed *that very 250 metric ton
MBT with 200 GW laser and ECM" to tow *exactly the same trailer* as the
PURPOSE-BUILT tractor I noted as an exception to the "seriously
overpowered" rule.

Regards,

Oerjan Ohlson
oerjan.ohlson@telia.com

"Life is like a sewer.
What you get out of it, depends on what you put into it."