A lot of worlds over 1g gravity. How do 1G thrust ships take off?

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phavoc
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby phavoc » Thu Feb 07, 2019 8:36 pm

AnotherDilbert wrote:
Thu Feb 07, 2019 7:05 pm
phavoc wrote:
Thu Feb 07, 2019 6:18 pm
Continue your lies if you wish, I no longer care.
Lulz. If by "lies" you mean facts and full quotes rather than out-of-context snippets, you betcha. As far as I'm concerned you earned every bit of snark thrown your way.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby AndrewW » Thu Feb 07, 2019 9:05 pm

Ok, lets just all get along and play nice.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Condottiere » Fri Feb 08, 2019 1:33 am

phavoc wrote:
Wed Feb 06, 2019 5:23 pm
Condottiere wrote:
Wed Feb 06, 2019 2:00 pm

Flying wing.
The Yb-49. Too bad both prototypes were destroyed. The B-36 replaced it as the strategic bomber.
https://www.google.com/search?q=b-36+n ... --Mm8P8pM:

For scale purposes. The B-36 even had an oboard reactor for a prototype propulsion system.
Two problems.

Extra lead protection tends to effect take off weight.

The destruction of the aircraft would either spew radioactive material into the atmosphere, or on the crash site.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Fri Feb 08, 2019 12:59 pm

Condottiere wrote:
Fri Feb 08, 2019 1:33 am
For scale purposes. The B-36 even had an oboard reactor for a prototype propulsion system.

Two problems.

Extra lead protection tends to effect take off weight.

The destruction of the aircraft would either spew radioactive material into the atmosphere, or on the crash site.
I'm flying over your airpsace, shoot me down, I dare you!

On a more serious note: Would the military at that time have considered that a problem? Some armies seem to have no issues with the environmental effects of depleted uranium armor and ammo, and some won't use it for the same reasons. There's also an argument right now in some militaries about the "necessity" of switching to lead-free bullets after several towns near military shooting ranges have reported unsafe lead levels from expended bullets.
phavoc
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby phavoc » Fri Feb 08, 2019 1:33 pm

Moppy wrote:
Fri Feb 08, 2019 12:59 pm
Condottiere wrote:
Fri Feb 08, 2019 1:33 am
For scale purposes. The B-36 even had an oboard reactor for a prototype propulsion system.

Two problems.

Extra lead protection tends to effect take off weight.

The destruction of the aircraft would either spew radioactive material into the atmosphere, or on the crash site.
I'm flying over your airpsace, shoot me down, I dare you!

On a more serious note: Would the military at that time have considered that a problem? Some armies seem to have no issues with the environmental effects of depleted uranium armor and ammo, and some won't use it for the same reasons. There's also an argument right now in some militaries about the "necessity" of switching to lead-free bullets after several towns near military shooting ranges have reported unsafe lead levels from expended bullets.
It was built as a technology demonstration. They did think about the accident risk, but this was the ramp up to the cold war plus you have to remember nuclear was everyone's brains. The b36 was huge, and the US wanted long range bombers to attack the Soviet Union from the continental US. It flew and collected test data with its 1megawatt reactor. It was based in dallas where it was built from a damaged bomber.

At about ten tons the reactor took up a lot of payload, but with nearly unlimited range it seemed like a good idea at the time. Kind of like the nuclear powered cruise missile the Russians have claimed to built (or was that a torpedo?). In any case the b36 was replaced because it was very slow. First the B47, and then by the B52 and ICBM that could be based in the US. I do thinkbthe Russians ever built an equivalent. It sure did cost the US a lot.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Fri Feb 08, 2019 3:41 pm

AnotherDilbert wrote:
Thu Feb 07, 2019 12:22 am
Moppy wrote: ... and a specific allowance for anti-grav vehicles (which admittedly arent spacecraft) to ignore atmosphere and world size for performance.
Ah, I think I have found what you mean. I believe that is just an exception to the Airborne Movement Rule:
Core, p130 wrote:Airborne Movement
Most aircraft (vehicles that use the Flyer skill) are designed for a specific atmosphere and planetary gravity. This means aircraft can only fly on worlds with Size and Atmosphere types within 2 of their world of creation.
...
In any case, aircraft require a minimum Atmosphere code of 1 in order to function. Aircraft descriptions include the Size and Atmosphere types of their world of manufacture.

Grav Vehicles
Vehicles using the Flyer (grav) skill employ anti-gravity technology rather than traditional methods of flight and so are unaffected by the Atmosphere and Size of worlds they travel on.

Grav vehicles still have a stated top speed, implying drag.


The Vehicle Handbook says:
VH, p16 wrote:Streamlined
High performance grav vehicles can be designed with aerodynamic hulls that allow them to travel at much greater speeds.
Does Mongoose 2 antigrav produce "thrust" in the conventional sense? It moves a certain thing at a certain speed, but how?

Is the maximum speed determined by power, or stability?

Since their aerodynamic hulls can be both open-topped and streamlined, and since I don't believe that open topped an air/raft is even remotely aerodynamic stable, what exactly is "streamlining"? Clearly from the art it has a pointed nose, but does it also include a computer that automatically trims the vehicle to keep it from tumbling?

Related question is how you breathe at mach 1 in a convertible, which lends credibility to anti-grav being a magic bubble.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Fri Feb 08, 2019 3:42 pm

AnotherDilbert wrote:
Thu Feb 07, 2019 12:22 am


Grav vehicles still have a stated top speed, implying drag.


The Vehicle Handbook says:
VH, p16 wrote:Streamlined
High performance grav vehicles can be designed with aerodynamic hulls that allow them to travel at much greater speeds.
Does Mongoose 2 antigrav produce "thrust" in the conventional sense? It moves a certain thing at a certain speed, but how?

Is the maximum speed determined by power, or stability?

Since their grav craft can be both open-topped and streamlined, and since I don't believe that open topped an air/raft is even remotely aerodynamic stable, what exactly is "streamlining"? Clearly from the art it has a pointed nose, but does it also include a computer that automatically trims the vehicle to keep it from tumbling, or keep it "gravitically stable" (whatever that means) as you fly over iron deposits and the local gravity increases suddenly. (edit: I know it can work in all gravity, but it has ample time during engine start to adjust to local gravity. I'm thinking of sudden slight changes, like hitting a pebble in a car. While stable aircraft become more unstable at higher speeds, unstable ones might not, and I don't know how grav-stability works).

Related question is how you breathe at mach 1 in a convertible, which lends credibility to anti-grav being a magic bubble.
core rulebook wrote:Vehicles using the Flyer (grav) skill employ anti-gravity technology rather than traditional methods of flight and so are unaffected by the Atmosphere and Size of worlds they travel on.
That's from core rules, and means atmosphere or vacuum, the speed of a grav-vehicle is unchanging.

edit: I wonder what the effect of weather is on grav-craft? If they're buffeted by winds they must have some kind of air resistance, but it's possible it negates that in the direction of travel, as otherwise vacuum or atmosphere would alter its speed.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby AnotherDilbert » Fri Feb 08, 2019 4:30 pm

Moppy wrote: Does Mongoose 2 antigrav produce "thrust" in the conventional sense? It moves a certain thing at a certain speed, but how?
We don't know any details. I believe it's just thrust, because of earlier editions and it doesn't break physics.

Moppy wrote: Is the maximum speed determined by power, or stability?
No idea. The bit VH about streamlining increasing top speed implies power and drag determines top speed.

Moppy wrote: Since their aerodynamic hulls can be both open-topped and streamlined, and since I don't believe that open topped an air/raft is even remotely aerodynamic stable, what exactly is "streamlining"? Clearly from the art it has a pointed nose, but does it also include a computer that automatically trims the vehicle to keep it from tumbling?
Streamlining, to me, means reducing air resistance, drag.
According to VH the air/raft would be faster if it were "Streamlined", so I assume it isn't classified as such.
I assume an air/raft has some built in computer to make it easy to operate. Otherwise It would be quite difficult to fly?

Moppy wrote: Related question is how you breathe at mach 1 in a convertible, which lends credibility to anti-grav being a magic bubble.
The air/raft isn't all that fast, it has a cruise speed of about 150±50 km/h (medium) according to the Core book.

To move at Mach 1 grav vehicles has to be both hi-tech and streamlined according to VH.

I would not assume anything about breathing unassisted in a Mach 1 airstream, whether we can build such a vehicle or not.

Note that grav vehicles can be used in vacuum, I do not believe that means the occupants of an air/raft can breathe in vacuum. (Earlier editions noted that vacc suits were needed.)
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby AnotherDilbert » Fri Feb 08, 2019 4:55 pm

Moppy wrote:
core rulebook wrote:Vehicles using the Flyer (grav) skill employ anti-gravity technology rather than traditional methods of flight and so are unaffected by the Atmosphere and Size of worlds they travel on.
That's from core rules, and means atmosphere or vacuum, the speed of a grav-vehicle is unchanging.
Quite, but so is the top speed of conventional aircraft and ground vehicles. It's a very simple system.

Moppy wrote: edit: I wonder what the effect of weather is on grav-craft? If they're buffeted by winds they must have some kind of air resistance, but it's possible it negates that in the direction of travel, as otherwise vacuum or atmosphere would alter its speed.
Since the premiss is true for all vehicles, you have to assume the same conclusion for all vehicles?

We simply have next to no detail about how things work in MgT2, so we can't really conclude much of anything based on MgT2 alone.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby phavoc » Fri Feb 08, 2019 5:10 pm

Moppy wrote:
Fri Feb 08, 2019 3:42 pm
Does Mongoose 2 antigrav produce "thrust" in the conventional sense? It moves a certain thing at a certain speed, but how?

Is the maximum speed determined by power, or stability?

Since their grav craft can be both open-topped and streamlined, and since I don't believe that open topped an air/raft is even remotely aerodynamic stable, what exactly is "streamlining"? Clearly from the art it has a pointed nose, but does it also include a computer that automatically trims the vehicle to keep it from tumbling, or keep it "gravitically stable" (whatever that means) as you fly over iron deposits and the local gravity increases suddenly. (edit: I know it can work in all gravity, but it has ample time during engine start to adjust to local gravity. I'm thinking of sudden slight changes, like hitting a pebble in a car. While stable aircraft become more unstable at higher speeds, unstable ones might not, and I don't know how grav-stability works).

Related question is how you breathe at mach 1 in a convertible, which lends credibility to anti-grav being a magic bubble.
core rulebook wrote:Vehicles using the Flyer (grav) skill employ anti-gravity technology rather than traditional methods of flight and so are unaffected by the Atmosphere and Size of worlds they travel on.
That's from core rules, and means atmosphere or vacuum, the speed of a grav-vehicle is unchanging.

edit: I wonder what the effect of weather is on grav-craft? If they're buffeted by winds they must have some kind of air resistance, but it's possible it negates that in the direction of travel, as otherwise vacuum or atmosphere would alter its speed.
I forget which book had stated that the air/raft is capable of reaching low-orbit, but the people would need to be wearing vac suits since it is unpressurized. MGT v1 revised Vehicle Handbook says about streamlining - Streamlined: Any closed grav vehicle can be designed with a high-speed Streamlined hull. This costs 300% of the Base Cost, loses 10% of the vehicle’s Spaces and multiplies Speed by five.

That seems a bit excessive of a speed boost, implying that open-topped vehicles are very unstreamlined. Early TL8 grav vehicles with a light chassis have a top speed of 300 kph. But that's the standard rule.

300kph is about 185mph. You'd definitely need a windscreen if you were facing forward, and passengers would need to be strapped in. Beyond that people have handled it before (WW2 fighters and bomber gunners for example). Though I would say for passengers who aren't unlucky airmen that they'd probably rebel and insist on some sort of light windscreen. Basically it should be possible, but certainly not practical. At mach 1 a person would not be able to take the airflow on their body, unless they were encased in a special suit and helmet that provided enough protection like a space suit (even then something would have to protect them from the wind flow jerking their head or body parts around and injuring/killing them.

Grav craft, just like aircraft and spacecraft, would be susceptible to weather. An air-raft flying through a storm, especially an open-topped one, could be lashed with high winds, rain, even lightning. There definitely should be a risk and piloting rolls. It's fair to ask if a craft of that type would be affected by water (it would be nearly similar to submergence).

I don't think that AG has any sort of magical bubble field around it. Basically I think there's an oversight in the design system for things like that.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Fri Feb 08, 2019 7:15 pm

Mongoose 2 allows any light grav vehicle to be open topped and has a note saying they require computer stabilisation. You certainly could exceed mach 1. That's information given to me by a friend who has the vehicle book so apologies if misquoted. As has been said, it could be a rules oversight.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby AnotherDilbert » Fri Feb 08, 2019 7:29 pm

Open topped is not defined in the system, it's a no cost choice for the designer.

VH, p16 wrote:Open Frame
The smallest Light Grav Vehicles can be built as an open frame with passengers effectively sitting on top or astride it. The g/bike is a good example of such a vehicle. They tend to be extremely fast but, without adequate computer-assisted controls, utterly lethal.

Both Open Frame and Streamlining increase speed, so a TL13+ streamlined gravbike can be supersonic.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Sat Feb 09, 2019 2:30 am

AnotherDilbert wrote:
Fri Feb 08, 2019 7:29 pm
VH, p16 wrote:Open Frame
The smallest Light Grav Vehicles can be built as an open frame with passengers effectively sitting on top or astride it. The g/bike is a good example of such a vehicle. They tend to be extremely fast but, without adequate computer-assisted controls, utterly lethal.
Both Open Frame and Streamlining increase speed, so a TL13+ streamlined gravbike can be supersonic.
Air/rafts are light grav. I'm amused by the idea of an open frame supersonic small air/raft. What size is "smallest"? I don't have vechicle book but modifiers like open frame usually give a cost per space, allowing size upgrades.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Condottiere » Sat Feb 09, 2019 4:37 am

1. There's an air/chair, somewhere.

2. A radioactive rocket is fire and forget; but you need to train to fly a nuclear plane.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby AnotherDilbert » Sat Feb 09, 2019 10:24 am

Moppy wrote: What size is "smallest"?
Open Frame can be max 3 Spaces, so perhaps two people and a little (250 kg) cargo.
Image

Note that only Open Frame explicitly mentions computer-assisted controls.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Sat Feb 09, 2019 3:43 pm

Image

Fighter jet can do "brakes off to mach 1" in about 30 seconds. Just imagine open frame at 0.99 mach :-)
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby AnotherDilbert » Sat Feb 09, 2019 4:30 pm

Moppy wrote: Just imagine open frame at 0.99 mach :-)
A Vacc Suit might make it a little more survivable?

How do pilots survive ejecting at supersonic speeds?
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Moppy » Sat Feb 09, 2019 5:37 pm

AnotherDilbert wrote:
Sat Feb 09, 2019 4:30 pm
Moppy wrote: Just imagine open frame at 0.99 mach :-)
How do pilots survive ejecting at supersonic speeds?
They usually don't, but ejection involves a lot more forces than regular flight.

Wikipedia gives all these awesome mach 2 speeds for jet fighters but that's for unloaded aircraft that don't have to save fuel or maneuver. Most jet dogfights were subsonic. Typical modern mission might be subsonic intercept and mach 1.6 sprint to launch missiles - no dogfight. I'm uncertain about the exact capability of the newest planes which have a supersonic cruise mode (mainly the F-22 and Typhoon).
Last edited by Moppy on Sat Feb 09, 2019 5:44 pm, edited 1 time in total.
phavoc
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby phavoc » Sat Feb 09, 2019 5:44 pm

Ejecting at supersonic speeds is usually a death sentence. A handful of people have survived, but most die. These are typical pilots though, and they aren't suited in something like a space suit. The last US pilot ejected from an F15 at Mach 1. He nearly died. Weapons officer did die

An SR71 had a flight incident and ejected its pilots at Mach 3. They were wearing space suits. One survived the other didn't.

The old B58 hustler had crew escape capsules for each crew member to protect them from high speed ejections. Not sure what the XB70 had, though since it was never production might not have gotten the full treatment.
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Re: A lot of worlds over 1g gravity. How do 1G thrust ships take off?

Postby Condottiere » Sat Feb 09, 2019 5:50 pm

The aircraft designers have to adjust the ejection process to mitigate the environment; eighty years ago, you slid back the canopy, if one existed, climbed out, and jumped.

The ejection seat, if I recall correctly, was an answer for Germany's new jets.

In Traveller terms, the whole cockpit is an ejection capsule, probably with embedded inertial compensators; more barebones would be incorporating that into, let's call it the throne seat, which only would require it for a turn.

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