Lifeboat Concepts

[Linwood]

I'm looking for some ideas and maybe a bit of design help for lifeboats - craft w/ more capacity and endurance than a re-entry pod but (thinking as a corporate accountant) as cheap as possible. The craft should be capable of carrying at least two emergency low berths (plus a standard low berth for the pilot) and sustaining power to the berths for at least three months. Other systems should be as basic as possible - cockpit basic sensors, minimal computer, etc. So far the three possibilities I've come up with are:

1) 1-ton power plant and a 1-G maneuver drive. That's probably the most efficient approach for a lifeboat w/ several emergency low berths (say for a passenger liner). May not be the best for a very small design.

2) Reaction thrusters and battery power. This assumes an initial thruster burn to set a course, a couple of course corrections, then a final thruster burn for landing. It also assumes a battery power pack can last weeks to months at a low discharge rate which doesn't seem to be defined by the MGT2 High Guard rules.

3) Reaction thrusters and a solar sail. This might be the best design for a deep-space accident where the nearest world might be years away. Assuming the sail can collect enough sunlight in deep space to continue to operate the craft....

Any thoughts?

 

[AnotherDilbert]

1) No need for vast 1 Dt drives, we can do much smaller drives.

2) Batteries can last you hours, not weeks, so forget about them.

3) Solar sails are locomotion, not power. Solar panels provide power. Neither will work away from a star, and very badly outside the habitable zone. A solar panel can keep you alive in a low berth for a long time, so we probably want that as a backup system.

4) Emergency low berths are expensive and power hungry at MCr1 and 1 Power each. The craft below would cost almost MCr 10 with emergency low berths. Perhaps worth it since it displaces less cargo per passenger.

Basic limitations: Smallest craft is 10 Dt. Minimum fuel is 1 Dt for 4 weeks.
Perhaps something like this:

10 Dt, 2G, 11 Low berths, MCr 2.8
No cockpit, relies on automation provided by Virtual Crew/0 (the single most expensive component).
Repair Drones to keep the craft working, operated by Expert software.
1 Dt cargo, normally filled with fuel for another 4 weeks.
Power plant with emergency power, plus a small battery, and solar backup.

 

[AnotherDilbert]

A slightly different concept uses a Stable as a minimum lifesupport environment to carry 20 people awake:

Like the last, but 15 Dt with a 10 Dt stable capable of keeping 20 people alive in discomfort.

 

[mancerbear]

Is the spreadsheet you're using available anywhere, AnotherDilbert?

 

[Linwood]

I didn't realize fractional-dton drives were allowed, AnotherDilbert. That opens up a number of interesting possibilities!

Also wondering why ordinary low berths are less power-hungry (per person) than emergency low berths. Seems a bit odd but I don't mind taking advantage of it.

I suspect my imaginary corporate accountant would axe the holographic controls as a needless luxury. But a backup computer and Virtual Crew 0 both make sense. Especially for groups of passengers who may not have Pilot skill.
Thanks!

 

[phavoc]

Depends on the type of lifeboat you want to carry. If your lifeboat is meant to stash people temporarily while help arrives, you can create lifeboats with simple acceleration couches or benches. The cruise ship Oasis of the Sea can hold 6,300 passengers and 2,400 crew. It uses the following:

As the size and capacity of modern cruise ship has increased there Oasis of the seas mega lifeboats becomes a potential problem of having sufficient space to fit the required number of lifeboats. The cruise ship Oasis of the Sea is fitted with 18 of the new mega lifeboats. A total of over 44 of the traditional 150 persons lifeboats would have to be fitted to accommodate the same number of passengers. The overall length of the Oasis of the Seas has an overall length of 360m. The typical length of a 150 person lifeboat would be approximately 9.6m. So if fitted at a single level they would take up a length of over 210m (noise-to-tail) on each side of the vessel.

The new CRW55 mega lifeboat has a catamaran hull with a length of 16.7m, breath of 5.6m, weights 17tonnes in stowed condition and 45tonnes when fully loaded with passengers and crew. It is fitted with two 170hp diesel engines providing a top speed of 6 knots and twin rudders for increased manoeuvrability.

More info here - http://www.rclcorporate.com/oasis-class-ships-revolutionize-the-lifeboat/

If you just need your lifeboat to survive planetary landing once, you have some design options that aren't part of the rules system. You don't need a full 1G motor, you just need to put-put around at say .25G or even a zippy .5G. Using continuous thrust even .25G is going to give you some get-up and go. Plus it's a lower energy requirement. Basically don't try to build a lifeboat using the design rules because they aren't applicable really to special needs. It's far better to simply create one and assign it a reasonable size, cost and operational standards. A lifeboat is dead meat in space.

There's also Fast drug that can be administered to the passengers. It compresses 60 days into 1, with no additional tech needed. That allows you to cram a lot of people into a small area. For something like that, instead of couches you could have people standing vertically with crash webbing as their 'walls'. This would allow for densely-packed lifeboats. But this model isn't necessarily a universal one. It works well for non-military ships with large civilian complements (like a liner). Military ships or anything that needs multiple lifecraft to survive battle damage would lean towards much smaller capsules capable of carrying just a few people. Fast drug works for long-term waits, but you'd probably also have more convential designs that allow for landing on planets.

But look towards the lifeboat tech that is out there in the real world and adopt some of the ideas for your 52nd century universe.

 

[baithammer]

2nd edition doesn't let you have fractional thrust values but allows for a 0 thrust one for station keeping setups such as stations and used for atmospheric braking.

A manoeuvre drive with Thrust 0 allows for station
keeping to maintain position (such as with an orbiting
station) but is not sufficient to move the hull any great
distance.

Low berths use 0.5t per person where as the emergency berths use 0.25t per person, but the low berths have an advantage on power as per 10 passengers 1 power is used while emergency berths use 1 power per 4 passengers. ( Have a feeling the emergency berths are supposed to have emergency battery power.)

Much like Central Supplies Cyroberth which has a 1 week battery supply.

It also assumes a battery power pack can last weeks to months at a low discharge rate which doesn't seem to be defined by the MGT2 High Guard rules.

Its covered in the battery rules where the battery is built with the amount power needed over a period of time, basically calculate the power needed over the time needed and use it to determine the battery required.

Batteries are often better performing at low energy draw over time or very big power draw at smaller time scale, has the added advantage of not needing fuel and its possibility of fuel explosion.

As for sizing you need to take into account economy of scale, the degree of emergencies faced in normal operation and wether or not the majority of the population can access docking arrangements.

 

[AnotherDilbert]

Is the spreadsheet you're using available anywhere, AnotherDilbert?

No, it's my own. It's not "finished" and not user-friendly, so I have not published it.

 

[AnotherDilbert]

I suspect my imaginary corporate accountant would axe the holographic controls as a needless luxury. But a backup computer and Virtual Crew 0 both make sense. Especially for groups of passengers who may not have Pilot skill.

The Virtual Crew/0 software has very limited skill, Pilot-0. I suspect any real Pilot will miss a real cockpit, and despise these sorts of soap-bubbles. But they are cheap...

 

[Reynard]

Wait, three months? A billion kilometer trip only takes a week to arrive at most mainworlds at 1g while an inaccurate jumps takes about a day. What is the intention of this lifeboat? Your other parameters seem to verify your regularly expect extremely deep space excursions something commercial vessels would not do. They tend to hug the 100D limit at both ends of a jump.

I dug out my copy of FASA's King Richard which features a lifeboat design for a luxury liners carrying a large number of crew and passengers. I'll convert up to HG2e standards and see how it looks.

 

[AnotherDilbert]

A regular utility boat can be used as a lifeboat in a pinch.

This 10 Dt example has a 6 Dt cargo-bay that can carry 6 Dt cargo, 6 Dt fuel, or seat 24 people on foldable benches.
It has a cockpit and Virtual Crew software, so can be piloted or can pilot itself.
Since it is an interface craft it is streamlined and has extendable fins.
It has a heavy-duty hull (aka regular) with light armour (proof against handguns).
2G, power plant with emergency power and a tiny battery.
All for the princely sum of MCr 2.6.

No long-term life-support or airlock, but there is always fast drug as Phavoc points out. And a bucket?

 

[Reynard]

Well, my turn. A dedicated and cheap lifeboat. I took some inspiration from the vague description from the King Richard packet.

The sphere design is for plugging in to a dedicated docking space. The aerofins give better control when re-entering Atmospheres of 4+ and normally are retracted for proper fitting in their dock. Not 3 months as desired but 4 weeks will get most to a world from anywhere in a system and most likely within reach of rescue operations. The lifeboat will carry 20 passengers and is crewed by 2-3 of the launching ship's crew assigned to that boat. Traveling in a micro-gravity is not an issue since people have endured hundreds of days in such conditions compared to 30 days max. These boats carry enough life support for the duration.

Commercial Lifeboat TL 9 MCr. 6.611
Hull: 15 ton, sphere, non-gravity hull, light
Armor: 0
M-Drive: Thrust 1
Power Plant: Fusion ( TL 8 ), Power 10
Fuel Tanks: 4 weeks operation
Computer: Computer 5
Software: Maneuver/0, Library
Sensors: Basic
Systems: 5 Emergency Low Berths, Stateroom, Aerofins
Cargo: 0.1 tons

 

[AnotherDilbert]

Commercial Lifeboat TL 9 MCr. 6.611
Hull: 15 ton, sphere, non-gravity hull, light

I can't argue with the savings from the non-gravity hull. For something that is not supposed to be used it might be worthwhile, 5% of the total cost of the craft is quite noticeable. Good idea!

The spherical hull is good for mounting on the outside of a non-streamlined, but a bit difficult to accommodate inside a streamlined ship, that is why I used a more boxy Close Structure configuration.


Not all systems are populated, containing a technological civilisation, or a human-habitable world so even if you can move to the habitable zone around the star you might have to wait for rescue. I think a solar panel as a backup to the power plant is a really good idea and a perfect companion to low berths.

 

[phavoc]

Something else to consider, especially if you consider the lifeboat to be a one time use object is that of an expanding one. There are a number of objects like trailers designed to increase their square footage by 200% when they are activated.

A lifeboat could be the same way. The area where the passengers are going to be doesn't need to be opeed up until use. So the 10m lifeboat would expand to 30m, with collapsed seating for the occupants. The lifeboat could still be designed to land on a planet by the inclusion of a one-time use anti-grav generator.

 

[Linwood]

A lot of awesome concepts here. Thank you all very much!

 

[Reynard]

I figure a commercial lifeboat is just that, an efficient and 'economical' unit especially for commercial vessels that normally don't take routes to out of the way systems or people wanting some security on a budget and willing to take a small chance. Carrying 20 people means it's not normally for Traders. Corporations have it to put their customers minds at ease knowing travel is very safe.

I mentioned a 'dedicated' docking space as both fluff and serious. It says this space was designed for these types of lifeboats rather the generic tonnage. The sphere fits in maintaining the ship's hull configuration while made for a fast ejection. The time it takes to launch represents getting often inexperienced passengers on board, secured in their assigned berth and the crew doing any prep and launch sequence. Picture the lifepods from Star Wars (and not Spaceballs) launching.

 

[phavoc]

Further muddying the waters would be that liners have a lesser or greater need (there are a number of variables here) to be able to self-transport passengers to/from a world or station. That would mean that some, if not all, have a limited number of small craft set up to transport passengers and cargo. These small craft could also be used to evacuate people from a stricken vessel.

Some 'lifeboats' would do double duty. The question might be would you store emergency equipment on the subcraft or have it stored in the launch bay so that it could be rapidly loaded in the event of an evacuation. Military lifeboats would need to have all gear stowed aboard since they are combat vessels. Civilian ones can get away with it a bit better since they aren't (usually) under fire and would have more time to evacuate.

 

[steve98052]

I've been on cruise ships a few times, and cruise ship lifeboats serve double-duty as tenders for ports that don't have piers for large ships. So, to equip a Starship with life floats, the analogous design would be a passenger craft perfectly suitable for carrying people to shore excursions on planets that don't have high ports -- but also usable for maintaining passengers for a long period of time in the event of a mishap that required evacuation.

Of the way I would design it would be a variation on the standard passenger shuttle. The changes that I would make would be to add to the power plant slightly, to give it the capability of running at the greatly reduced life support level that would be needed to maintain a few crew awake and active (but probably very bored), but all of the passengers at one-sixtieth metabolism due to Fast Drug. I would also boost the fuel storage to the point that it had enough endurance for the ship to wait for a rescue mission, even if the rescuers took a long time to locate the ship, such as in cases of a misjump.

Of course, a misjump to deep space would most likely mean all hands lost; presumably only a misjump to a star system would be survivable. On the other hand, if a ship stocked enough Fast Drug and had enough power plant endurance, it could launch a distress signal even from deep space, with the years it would take for the distress signal to reach the nearest inhabited world, and still expect to be rescued. Such a design would make the most sense at technology levels where unreliability of jump drives made misjump a meaningful hazard of travel.

 

[Reynard]

Remember the iconic 20 ton launch is also designated a lifeboat. In a dire emergency you pack it with people. It's normally a cargo hauler with no actual accommodations for passengers. The life support is meant for very short durations of hours and at best they are used as lifeboats within the 100D range of a planet similar to the 2 person reentry pod. Most other small craft can do the same thing and passenger craft lets you ride in some comfort. Problem also is they carry very few people safely or long duration.

A true lifeboat is first and foremost an emergency craft designed to get a large number of people to safety for the volume and cost. You strip it to the essentials of emergency transport. That's why emergency low berths are great. Passengers/crew are out of the way and as safe as possible in a small volume and not consuming volume in the form of life support. No need to constantly replace perishables and water or tax the air supply. Transporting 22-23 people in a space 3/4 the volume of a launch isn't bad. Unlike a reentry pod, a lifeboat is reusable as any small craft except a distributed hull version if it were to go planetside.

I think I made this as compact as possible. You could have larger versions. The passenger capacity is to haul an optimal number of people mostly on larger vessels that have high passenger capacity to their volume. Larger ships can afford the tonnage for multiple lifeboats.

 

[Condottiere]

Establish the minimum standards required under Imperium law and/or planetary registry, then you can figure out where you can cut corners.

Our standard lifeboat tends to be more a maid of all work.

The most efficient variant would have a manoeuvre drive that is directly connected to the batteries, that are recharged by either an emergency fusion reactor or solar panelling, depending on your distance to a light source.