How long to fire up the Quattro?

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ochd
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How long to fire up the Quattro?

Postby ochd » Mon Aug 07, 2017 12:45 pm

Another minor question, just for my hard-science scifi confidence...

I've ruled that it takes 1d6 minutes to start up an M drive and take off, with the potential to do it in 1d6 x 10 seconds (at -2 to the check) if need be. Does that sound reasonable? Of course, this only matters for combat or other situations where a quick getaway is crucial. I guess a TL7 or 8 reaction drive would take longer, maybe, but those would be the exception.

Also, I don't envision M drives having a "blast" effect like a reaction drive would. That is, like grav cars and so on, you could be stood next to a spacecraft or starship that is taking off and landing and not be adversely affected? Or maybe the manipulation of gravity might knock people of their feet?

Thanks,

Dan.
Jeraa
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Re: How long to fire up the Quattro?

Postby Jeraa » Mon Aug 07, 2017 12:58 pm

ochd wrote:
Mon Aug 07, 2017 12:45 pm
I've ruled that it takes 1d6 minutes to start up an M drive and take off, with the potential to do it in 1d6 x 10 seconds (at -2 to the check) if need be. Does that sound reasonable? Of course, this only matters for combat or other situations where a quick getaway is crucial. I guess a TL7 or 8 reaction drive would take longer, maybe, but those would be the exception.
The space combat chapter indicates a system can be shut down in a single round, or started up in a single round. Space combat rounds are 6 minutes long.

It could be a 2 step process, however. If the ship had been powered down, you would need to power up the power plant first before starting the engines.
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Re: How long to fire up the Quattro?

Postby Reynard » Mon Aug 07, 2017 1:04 pm

It's been described in other editions of Traveller so I envision MgT ships to also have lifters as a subsystem of the maneuver drive. Explains why so many images of downports having VTOL landing pads and how ships maneuver into landing bays when their image shows non-wheeled landing struts. As far I've experienced, there have been no stories describing people knock down when an air/raft next to them lifts off.

Usually I see the power system powered up and ready to feed the maneuver drive at a moment's notice with no more effort than turning the ignition key in a car only bigger. Closest I could see at taking off is running a Standard Operation System Checklist before launch but even that can be ignored in emergencies.
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Re: How long to fire up the Quattro?

Postby ShawnDriscoll » Mon Aug 07, 2017 2:17 pm

It's always good to have a picture of your ship taking off or landing, so players have an idea of the visual coolness that's involved with their ship. Pinterest has all the Traveller-inspired images you'd need for your game session's group.
ochd
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Re: How long to fire up the Quattro?

Postby ochd » Mon Aug 07, 2017 8:20 pm

Jeraa wrote:
Mon Aug 07, 2017 12:58 pm
The space combat chapter indicates a system can be shut down in a single round, or started up in a single round. Space combat rounds are 6 minutes long.
Ah, cool. That's pretty clear, then.

Given that rule is in the context of space combat (where minimum time units are 6 minutes), I think it's fair enough to utilise a 1d6 minute timeframe for non-space combat situations (e.g. trying to make a quick getaway from a starport).

Dan.
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Re: How long to fire up the Quattro?

Postby steve98052 » Wed Aug 23, 2017 2:33 pm

Although Maneuver drives do not have the plume of exhaust like reaction drives, in their first versions, at low technology levels, they do radiate a lot of excess heat because they operate inefficiently. So, although you may not be blasted off into space by a plume of exhaust, you might be baked by the radiated heat. That is only a problem at the technology level when Maneuver drives are first introduced; after that, the energy is used for maneuver thrust, not radiated as waste heat.
ochd
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Re: How long to fire up the Quattro?

Postby ochd » Sat Sep 02, 2017 9:55 am

A different subject, but related to M drive performance: could a 200t ship with 2G drive raise a crashed far trader from the bottom of a shallow body of water? Assume standard gravity and it has the necessary clamps and cables and so on.

Thanks,

Dan.
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Re: How long to fire up the Quattro?

Postby phavoc » Sun Sep 03, 2017 12:30 am

I would say no. The amount of M-drive is inconsequential because they are at the bottom of a gravity well and the M-drives aren't used for lift. The ships anti-gravity system is used for lift and the engines for movement. There is a 33% greater displacement which should be too great for the lift system. Now if it were the other way around, and both ships were empty of cargo and minimal fuel, then that would be potentially possible.

Even though mass is not considered in the drive system, you have to use something to measure things like this.
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Re: How long to fire up the Quattro?

Postby Jeraa » Sun Sep 03, 2017 1:44 am

The rules say differently. "The necessary clamps and cables and so on" is rather vague, however. Could count as a tow cable, or a docking clamp. Either way, it is possible.

Your ship is 200 tons. The 2-Gdrive is 2% of that, or 4 tons.
Far traders are 200 tons. Combined with your own 200 tons, that is 400 tons.
Since your 4 ton drive is 1% of your combined tonnage, your performance drops to 1g.

There is no separate "anti-grav system". I would therefore assume it is built into the drive. If the drive is capable of moving it, then it can.
ochd
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Re: How long to fire up the Quattro?

Postby ochd » Sun Sep 03, 2017 11:49 am

Thanks Jeraa.

I was thinking that lift is a function related to the M drive but not necessarily the same as horizontal movement. That is, while a ship with 2G acceleration is capable of VTOL, I imagine it doesn't accelerate as quickly doing so as it would taking off and climbing like an aeroplane. But then, what matters in this case is not what acceleration is achieved but whether the drives are capable of lifting 400tons of weight, which as you say the rules indicate they are.

phavoc: I'm curious as to your differentiation of anti-gravity vs movement. I thought they were both a function of the ship's maneuver drives. Also, I don't follow this sentence -- "There is a 33% greater displacement which should be too great for the lift system" -- where does your 33% figure come from?

Thanks,

Dan.
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Re: How long to fire up the Quattro?

Postby Reynard » Sun Sep 03, 2017 12:25 pm

I'm at work at the moment and can't access my collection of Traveller editions but I remember it's been said non-reaction drives are reactionless because they push or pull on either gravity wells (gravitic drives) or they interact with other exotic forces (Maneuver drives). There is no direct expulsion of matter or energy so no danger of exhaust backwash. That's why reactionless drives use energy from the power plant to produce motive ability rather than drawing on fuel mass directly which is ejected.

Firing up the maneuver drives should be almost as quick as starting a car and moving forward since it's feeding power to the drive and the drive acts.
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Re: How long to fire up the Quattro?

Postby phavoc » Sun Sep 03, 2017 5:44 pm

ochd wrote:
Sun Sep 03, 2017 11:49 am
Phavoc: I'm curious as to your differentiation of anti-gravity vs movement. I thought they were both a function of the ship's maneuver drives. Also, I don't follow this sentence -- "There is a 33% greater displacement which should be too great for the lift system" -- where does your 33% figure come from?

Thanks,

Dan.
The percentage is based on the displacemen's of the two vessels. A free trader displaces 200 tons and a far trader 300 tons, and you were asking about the free trader moving the far trader, hence the 1/3rd displacement difference.

The grav question has been around a long time in Traveller. Some argue that it should not be there, but various canon rules have called it specifically out. GURPS, for example specifically included mass in its antigravity equipment.

Some say that MGT does not, but if you look at the illustrations you'll see that in some cases no ship without vertical lift could ever maneuver into some of the areas it's shown. Nor could ships land unless they were tail sitters.

Maneuver drives provide thrust only. Assuming you had lifting surfaces you could operate like an aircraft, but most starship do not. There has to be some other mechanism to provide lift and maneuverability in a grav well. I've seen some argue that smaller thrusters that operate similar to maneuverify drives could be substituted, however when you havery antigravity tech that becomes a very backwards way of doing anything.
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Re: How long to fire up the Quattro?

Postby ochd » Sun Sep 03, 2017 9:36 pm

Ah, right. A far trader is 200 tons, at least according to my High Guard, so I was thinking of one 200 ton ship (not a Free Trader actually but the Harrier from Drinax) lifting another 200 ton ship. But if you were thinking of 300 tons I see where you're coming from ... except wouldn't it be 1/2 instead of 1/3, 300 being 1.5 X 200?

Anyway, that aside, is there some rule of thumb about what size/power of anti-grav is needed to lift weight x?

Thanks,

Dan.
phavoc
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Re: How long to fire up the Quattro?

Postby phavoc » Mon Sep 04, 2017 7:36 am

Yes, you are correct. I reversed the tonnage numbers.

For lift I don't have a firm rule ofbthumb, but generally would consider 20% the max.
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Re: How long to fire up the Quattro?

Postby Reynard » Mon Sep 04, 2017 11:41 am

MegaTraveller lists Anti-grav and Thruster maneuver drives by 'units', 65 Mwt, 13.5 m3 and 27 tons and 70 Mwt, 13.5 m3 and 35 tons respectively. There's no straight formula, you determine numbers of units by hull tonnage and Gs desired. You then take the thrust in Gs divided by vehicle loaded weight then subtract 1 for the maneuver thrust which, cross-referenced on a table, shows the ship or thrust based vehicle's max speed in a vacuum. For your question about lifting weight X, you can determine how much excess weight affects a ship/vehicle's performance until it can no longer operate.

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