Chris there's not just the AT-AT and AT-ST walkers out there ..there's AT least a dozen more ...like this lot 😆
AT-TE..All-Terrain Tactical Enforcer
AT-RT..All Terrain Recon Transport
AT-M6..All Terrain MegaCaliber Six
AT-AP..All Terrain Attack Pod
AT-OT.. All Terrain Open Transport
AT-DP...All Terrain Defense Pod
AT-MA..All Terrain Mobile Artillery
AT-ACT ...All Terrain Armored Cargo Transport
And just cause ya asked about mountainous terrain they have this one 😆
MT-AT Mountain Terrain Armored Transport
There's  more besides those from the TV shows..books and comics.

Quote from: steelpillow on February 17, 2025, 01:10:53 PM

Quote from: perttime on February 17, 2025, 04:12:57 AMThe XFV-12 was an interesting concept, and it looked pretty cool too ... except for the A-4 derived cockpit and nose, and the F-4 intakes.

I wonder if they've figured out why it failed. The idea was to blow air down through the slots, entraining more air from above to boost the thermodynamic efficiency and hence the thrust.......

I seem to recall that the augmented thrust concept did not scale up well, and did not supply the anticipated levels of thrust.  Worked ok in small lab tests.   

Quote from: steelpillow on February 17, 2025, 01:10:53 PM

Quote from: perttime on February 17, 2025, 04:12:57 AMThe XFV-12 was an interesting concept, and it looked pretty cool too ... except for the A-4 derived cockpit and nose, and the F-4 intakes.

I wonder if they've figured out why it failed. The idea was to blow air down through the slots, entraining more air from above to boost the thermodynamic efficiency and hence the thrust.
The earliest attempt at this kind of induction thrust that I have found was an idea by aircraft pioneer JW Dunne, ca. 1901. It also failed for Rockwell's XFV-1, falling way below lab test predictions. But it would later work for Dyson with his airblade, that we now find everywhere.
Maybe today we could make it work for VTOL. What-if, indeed!

It failed because it doesn't work at full size. It works on models but it doesn't scale, none of the designs actually built that tried to use an entrained air concept functioned worth a damn. The Avrocar was the first, next was the Lockheed XV-4 and then the XFV-12, which was built even though it had already been demonstrated by the two previous machines that the concept didn't work. On the XV-4 the "lift system" took up the entire centre section of the fuselage. The system was so crappy that the second airframe was converted to using six J85s, four as lift jets and two for propulsion.
It could work on a drone, but it's ridiculously complicated when compared to a simple rotor system, and if it's a drone designed solely for attack, a waste of money. 

Quote from: PR19_Kit on February 16, 2025, 09:27:25 AMOh yes, I was heavily involved with its production. I was a founder member of the Support Group for the real train at the Shildon Museum, and Rapido asked us to help out in getting it correct. And it certainly IS correct. 

I've got two of them, an early one and a the later WhatIf version in the InterCity livery.

Colour me jealous! 

Quote from: jcf on February 17, 2025, 03:49:16 PMIt failed because it doesn't work at full size. It works on models but it doesn't scale,

Makes sense. Viscosity, Reynolds number and all that. Odd that such experienced pros didn't think of that and check it out first.

Doubt it'd work in a denser and more viscous fluid like water either, though that would be more down to the back-pressure where the jet hits the surrounding water. To get a jet boat to go fast you have to squirt it out above the waterline, not much opportunity for entrainment there.

Dunne's idea was a weird vortex system. The hull is a hollow tube with wide end caps and a prop pushing forwards. A propeller in the middle drives the fluid forwards to the bow, where it turns at the bow cap to run down the sides, then gets sucked back in at the stern cap to recirculate forward again. This entrains sufficient ambient fluid to generate thrust. Hiram Maxim (of machine-gun fame) dissed one of his ideas, and it was probably this one. Dunne also sketched a parachute with a coaxial rotor blowing up under it, same idea in mind.
But what-if...

Quote from: perttime on February 17, 2025, 04:12:57 AMThe XFV-12 was an interesting concept, and it looked pretty cool too ... except for the A-4 derived cockpit and nose, and the F-4 intakes.

Wern't they just being used for ease of production on the prototype ? Or has my memory gone over time ?

It does look "cool" as you say. I built the Anigrand one (who appear to have a fair bit of new stufff coming out) many years ago.

Quote from: Weaver on February 17, 2025, 11:54:17 AMI'll have a crack at answering that.

We do know something about the science that sci-fi settings use, because we can see what's possible and what isn't on the screen and in the background books and materials.

I can't get into it like that I'm afraid. Brains just not wired that way. It's fiction and thus everybody's interpretation can be different. Howeveer I'm obviously in the minority on the Board so I Think we'll just have to agree to disagree H 

Quote from: NARSES2 on February 18, 2025, 05:47:04 AM

Quote from: Weaver on February 17, 2025, 11:54:17 AMI'll have a crack at answering that.

We do know something about the science that sci-fi settings use, because we can see what's possible and what isn't on the screen and in the background books and materials.

I can't get into it like that I'm afraid. Brains just not wired that way. It's fiction and thus everybody's interpretation can be different. Howeveer I'm obviously in the minority on the Board so I Think we'll just have to agree to disagree H 

I think the difference between sci-fi and fantasy is that sci-fi still has a logical scientific framework, just with a few things changed, such as advanced, and variably improbable technologies. The consequences of that technology should be logical, although there's plenty of bad sci-fi that ignores inconvenient inconsistencies. Fantasy, on the other hand, has magic, which is allowed to break cause and effect in completely inconsistent ways. However, if you can't see it that way, then fair enough: you're entitled to your point of view.

Quote from: Weaver on February 18, 2025, 08:21:02 PMI think the difference between sci-fi and fantasy is that sci-fi still has a logical scientific framework, just with a few things changed, such as advanced, and variably improbable technologies. ... Fantasy, on the other hand, has magic, which is allowed to break cause and effect in completely inconsistent ways.

Then of course there's the old saw that "any sufficiently advanced technology is indistinguishable from magic". Mix in a bit of what we regards as pseudoscience, such as telepathy, or find a home for your fairies in some handy parallel Universe, and you blur the distinction. Which is why the whole mess if firmly classified as the F&SF - Fantasy and Science Fiction - genre. F is one end of the piece of string, SF is the other.

"Fantasy is the impossible made probable. Sci-Fi is the improbable made possible." - Rod Serling

"Science fiction is something that could happen - but you usually wouldn't want it to. Fantasy is something that couldn't happen - though you often only wish that it could." - Arthur C. Clarke

Any kind of tank that is either gigantic or has more than one turret is a bad idea.

Quote from: seadude on February 19, 2025, 11:34:40 AM"Fantasy is the impossible made probable. Sci-Fi is the improbable made possible." - Rod Serling

"Science fiction is something that could happen - but you usually wouldn't want it to. Fantasy is something that couldn't happen - though you often only wish that it could." - Arthur C. Clarke

I like those. Very useful descriptors, thanks.

Quote from: Rick Lowe on February 19, 2025, 08:32:08 PM

Quote from: seadude on February 19, 2025, 11:34:40 AM"Fantasy is the impossible made probable. Sci-Fi is the improbable made possible." - Rod Serling

"Science fiction is something that could happen - but you usually wouldn't want it to. Fantasy is something that couldn't happen - though you often only wish that it could." - Arthur C. Clarke

I like those. Very useful descriptors, thanks.

They are indeed 

Quote from: kerick on February 19, 2025, 06:52:34 PMAny kind of tank that is either gigantic or has more than one turret is a bad idea.

I think some of the 1930's types with separate mg turrets were reasonable designs, but that was from a period where the tank was mainly seen by a lot of armies as an infantry support vehicle.

Multi turreted tanks and utterly useless as it seems ...russian  T-28 ...T-35 ...KV-VI super heavy tank..not real ..SMK ..KV-4..KV-7 T-100 ...those are all russian by the way.
Bet the more I'd look the more I'd find...there's so many bad ideas in the world of armoured vehicles we could have GB which would last a yr 😉 😀