1g Ships and Size:7 worlds...

[Enoki]

Better use of shock waves: XB-70 Valkyrie (Wikipedia)

The fold-down wingtips trapped the shockwave from the engine inlet under the aircraft to maximize compression lift.

Regrettably, advances in radar technology rendered it obsolete before it entered production.

Radar no. Surface-to-air missiles, yes. With first gen SAM's a supersonic aircraft could often outrun the firing and intercept envelope of the missile. Second gen and on, not so much.

 

[Grav_Moped]

Radar no. Surface-to-air missiles, yes. With first gen SAM's a supersonic aircraft could often outrun the firing and intercept envelope of the missile. Second gen and on, not so much.

It was designed to exploit the "blip-to-scan" hole in Soviet radar (outrun the tracking sweeps to prevent precise location). Soviets had high-altitude SAM capability (took out a U2) in 1960, though it might not have been terribly effective back then.

 

[Enoki]

It was designed to exploit the "blip-to-scan" hole in Soviet radar (outrun the tracking sweeps to prevent precise location). Soviets had high-altitude SAM capability (took out a U2) in 1960, though it might not have been terribly effective back then.

You mean the analog computers of the day. A radar could easily track it. The problem was early analog computers were too slow at processing data to keep up with very fast targets. The other problem was early SAMs were also slower and usually shorter ranged meaning they lacked the intercept envelope to take on targets moving at high Mach numbers, like the B-70.
The missile the Soviets were developing to intercept the B-70 at that time was the V-1000. It could intercept a target at 35 miles from the launch point up to 82,000 feet in under a minute. The fire control computer, the M 40 then M 50 was enormous.

It was also to serve as a limited ABM and had a pretty large conventional warhead to make a near miss as effective as a full intercept.
(I'm currently writing a book on SAM development from 1935 to 1955...)

 

[Grav_Moped]

You mean the analog computers of the day. A radar could easily track it.

That's the blip-to-scan issue. Radars could "see" them (as in, get a return from them), but the images on the displays relied on the target being in roughly the same spot on the display for consecutive sweeps to generate a bright "blip". If the target moved fast enough relative to the sweep rate, the resulting "blip" would show up as a faint streak of multiple distinct returns rather than a bright blip -- often faint enough to fade into the background and thus "invisibility".

Improved radars, and computerized image processing replacing the use of the cathode ray tube display itself for the processing, solved the blip-to-scan problem.

 

[Enoki]

That's the blip-to-scan issue. Radars could "see" them (as in, get a return from them), but the images on the displays relied on the target being in roughly the same spot on the display for consecutive sweeps to generate a bright "blip". If the target moved fast enough relative to the sweep rate, the resulting "blip" would show up as a faint streak of multiple distinct returns rather than a bright blip -- often faint enough to fade into the background and thus "invisibility".

Improved radars, and computerized image processing replacing the use of the cathode ray tube display itself for the processing, solved the blip-to-scan problem.

That makes zero difference to the guidance system that is using an analog computer to do the guidance. The operator simply selects the target and locks the fire control onto that target. In most cases, the fire control radar is conical scan with a very high PRF, or a monopulse with a high PRF, and in some cases continuous wave. In all three cases the pulse repetition frequency is so high it makes no difference against an aircraft. They can all track one without difficulty. Slew rates for radars even in the 50's was sufficient to keep up with most aircraft.
The problem comes when the analog computer time between calculations is in seconds and it takes so long to run the calculation that by the time it's finished, the system produces an error. That is, the computers were so slow back then that they couldn't keep up with very fast targets. A very fast plane at high altitude in the late mid to late 50's could literally outrun the computer.
Although beam riders couldn't really take on high altitude targets at long range, they could easily track a medium or lower altitude very fast plane and their engagement envelope was limited by the gather time for the missile, its relatively short range, and the speed of the missile itself.

An example of how this worked would be Nike Ajax. The time between guidance updates is about 5 seconds. That's how slow the analog computer used at the time was. Against a Lockheed X-7 drone, the missile system simply couldn't keep up with the speed of the target. It could track it just fine, but the computer couldn't tell the missile where to go to hit it because by the time it made the calculation, the missile wasn't where it was calculated to be. (The US Army actually hushed this whole thing up and classified it because it was a huge embarrassment).

The tour de force SAM system of the early to mid-50's was the S-25 Berkut system around Moscow. That shows you what having unlimited funds can buy! Each missile site could locate and track 6 targets simultaneously with its single pair of TWS Yo-Yo radars. These were tied into 6 analog computers each controlling one missile in flight to a target. For the time period, it was an amazing system.
Problem was it cost a national fortune to build it. The system made the Manhattan Project look downright cheap. This is something to keep in mind when building large ships and military forces in Traveller for wargame type scenarios. Even the polities in the game don't have unlimited cash...

The two have a six segment beam as they rotate that forms an X in the sky that marks the target. Each segment tracks a separate target feeding to a separate computer.

 

[Grav_Moped]

That makes zero difference to the guidance system that is using an analog computer to do the guidance. The operator simply selects the target and locks the fire control onto that target. In most cases, the fire control radar is conical scan with a very high PRF, or a monopulse with a high PRF, and in some cases continuous wave. In all three cases the pulse repetition frequency is so high it makes no difference against an aircraft. They can all track one without difficulty. Slew rates for radars even in the 50's was sufficient to keep up with most aircraft.
The problem comes when the analog computer time between calculations is in seconds and it takes so long to run the calculation that by the time it's finished, the system produces an error. That is, the computers were so slow back then that they couldn't keep up with very fast targets. A very fast plane at high altitude in the late mid to late 50's could literally outrun the computer.
Although beam riders couldn't really take on high altitude targets at long range, they could easily track a medium or lower altitude very fast plane and their engagement envelope was limited by the gather time for the missile, its relatively short range, and the speed of the missile itself.

An example of how this worked would be Nike Ajax. The time between guidance updates is about 5 seconds. That's how slow the analog computer used at the time was. Against a Lockheed X-7 drone, the missile system simply couldn't keep up with the speed of the target. It could track it just fine, but the computer couldn't tell the missile where to go to hit it because by the time it made the calculation, the missile wasn't where it was calculated to be. (The US Army actually hushed this whole thing up and classified it because it was a huge embarrassment).

The issue I'm discussing is initial detection, not targeting. If the guy at the strategic-level scope doesn't see it, he can't tell the guy launching the missile to try to lock on in the first place.

 

[Enoki]

The issue I'm discussing is initial detection, not targeting. If the guy at the scope doesn't see it, the guy launching the missile won't know to target it in the first place.

Initial detection is no big problem. You detect the aircraft for most SAM systems at that time out at 50 to 100 miles so you have lots of time to track them. The surveillance radar site hands off the target to the SAM site that then starts engagement with their fire control radars as the target comes into range. For the mid to late 50's this range would typically be 30 to 60 miles out from the site for high altitude targets.

 

[Grav_Moped]

Initial detection was the problem. The surveillance radars displayed the radar returns directly on the cathode-ray tube display, and the way they rendered the image was that a reflection made a blip at a point on the display proportional to the strength of the reflection. "Noise" also made blips. Repeated adjacent reflections from the same target from multiple sweeps made a large bright blip (due to phosphor decay lag and the imprecision of the electron beam) and were recognizable as targets (aircraft). Repeated non-adjacent reflections from the same target (because the aircraft moved far enough between sweeps that the individual return blips didn't "blend together") looked like a faint dotted line that could be mistaken for background noise.

 

[Condottiere]

1. Predictive: I vaguely recall hearing that some mole revealed Gary Power's flight plan.

2. With the Ef One Seventeen over Yugoslavia, not clearing the path beforehand, an observer near the Italian airfield, and using the same plath path.

3. Also, cheaper to load a nuclear warhead in a one use intercontinental missile, and less embarrassing if any of the crew survived shootdown.

 

[Grav_Moped]

That is, the radar system didn't "know" that subsequent reflections of the same aircraft were in fact coming from the same object, it was just painting dots on a matrix of phosphor dots using an electron beam. Object permanence was a matter between the time delay of the dots dimming before the next blip from the electron gun lit them back up, and the operator's skill.

It wasn't until the radar images needed to be combined (for SAGE on the US side) and presented as a whole, that computers got to the point of "knowing" that the blip at x₁,y₁ was the same object as the blip at x,y from a fraction of a second earlier.

 

[Grav_Moped]

2. With the Ef One Seventeen over Yugoslavia, not clearing the path beforehand, an observer near the Italian airfield, and using the same plath path.

And throwing literally everything they had in the path, straight up, blind.

 

[Condottiere]

He did open up the bomb bay.

If I'm not mistaken, they design them toothed now.

 

[whartung]

For what it's worth, there was an interesting starship in T4 that I don't believe I've seen anywhere else -- the "Military Landing Ship Infantry."

That's a pretty cool ship, exactly the kind of exotic kit you can get out of something like FF&S.

I would question the need for both drives however. There's a bit of logic with the premise that the HEPLaR is a backup to the thruster plate drive, with a concern about reliability. But 11 hours isn't really that much maneuver time in the big scope of things. Plus the added maintenance of both drives. Better to wait out the reliability and then pick one over the other. I'd also imagine once the Thruster Plate tech did get reliable enough, they'd refit these ships to yank the HEPLaR out of it, either as a safe way to simply decommission it, or for using the extra space.

 

[Straybow]

Back to the original question, on a size 7 world with comparable density, surface gravity would be 7/8 G. A 1G ship could take off and reach orbit in 12 minutes, and then accelerate to orbital velocity in another hour (maybe less).

 

[Spinward Flow]

Back to the original question, on a size 7 world with comparable density, surface gravity would be 7/8 G. A 1G ship could take off and reach orbit in 12 minutes, and then accelerate to orbital velocity in another hour (maybe less).

Correct. That performance profile has never been in doubt or at issue.
The problem is ... what do you do at Size: 8-A when surface gravity is 1G+ if you've (only) got a 1G maneuver drive?

The simplest solution is to ... reach for 2G maneuver drives (minimum) and the problem "goes away" ... but not everyone likes that answer (see: Free Trader, Fat Trader, et al.). The advantage of 2G+ maneuver drives is that you can VTOL into any suitable "parking spot" on a terrestrial surface, whether that's at a starport berth or not. Note that this capability would be required for fuel skimming ocean water in atmosphere (unless the downport includes slipways into water rivers/ocean, no doubt for a service fee).

An alternative solution is to make use of orbital shuttle transfer services (Cr10 per ton of cargo, Cr10-120 per passenger) (LBB2.81, p9), allowing you to keep your 1G maneuver starship orbital rather than needing to land at the downport. However, this alternative requires a minimum level of starport infrastructure support (unlikely to be found at type D, almost unheard of for type E, and definitely not available for type X). Even type C starports can be hit or miss with orbital shuttle transfer services (some will, some won't, depends on location and local tech levels for support). It's only once you get up to type A and B starports that you're basically guaranteed access to orbital shuttle services should you need them.

Being able to land at a downport and take off for orbit again can become a "barrier to profitable commerce" with some mainworlds along a particular trade route (such as the Spinward Main, for example). It is therefore the responsibility of 1G starship operators to know which mainworlds along a particular route need to be "bypassed" as not worth the cost of conducting trade operations at that location (the true "backwater" worlds) in order to avoid them and the damage to their balance sheets that jumping into (and out of?) those systems will do to the annualized accounting of operations for the year in terms of profits and losses.

And then there's the fools who LAND ONCE and are never able to lift off ever again afterwards with their starship ...

 

[mike wightman]

For a size 8-A world build your starport at altitude and use your streamlining to generate enough lift to fly to orbit. Traveller ships fly in atmosphere like planes, they do not fly like rockets.
Evidence - all the illustrations and the deck orientations.

 

[Grav_Moped]

For a size 8-A world build your starport at altitude and use your streamlining to generate enough lift to fly to orbit. Traveller ships fly in atmosphere like planes, they do not fly like rockets.
Evidence - all the illustrations and the deck orientations.

Counter-argument: What's the lift-to-drag ratio of a Type A Free Trader?

I mean, the Type R has wings, so maybe it can manage. They don't look like they'd provide adequate lift at reasonable takeoff speeds, but it's at least hanging a lampshade on the problem.

 

[atpollard]

Counter-argument: What's the lift-to-drag ratio of a Type A Free Trader?

I mean, the Type R has wings, so maybe it can manage. They don't look like they'd provide adequate lift at reasonable takeoff speeds, but it's at least hanging a lampshade on the problem.

With enough velocity even a BRICK will fly.

 

[mike wightman]

Counter-argument: What's the lift-to-drag ratio of a Type A Free Trader?

I mean, the Type R has wings, so maybe it can manage. They don't look like they'd provide adequate lift at reasonable takeoff speeds, but it's at least hanging a lampshade on the problem.

Enough for it to fly into orbit.
A 1g continuous thrust engine that requires no oxygen from the atmosphere or reaction mass is not something that needs to worry about airframe aerodynamics, not when its TL9 control surfaces and flight computer can take care of it with only a streamlined hull.

 

[mike wightman]

With enough velocity even a BRICK will fly.

Yup, and a 1g continuous thrust engine with TL9 control surfaces and flight computer make it achieve orbit.