Air/Raft Power

[Timerover51]

While working on a discussion in another thread, I went back to look at the data on the standard Air/Raft, and finally decided to ask about something that has bugged me for years. Per Supplement 8: Library Data (A-M), the following is stated regarding the Air/Raft.

Range in time or distance is effectively unlimited; refuelling (sic) (recharging) can be accomplished from a starship power plant in a few hours every ten weeks or so.

First, refueling does not strike me as the same as recharging. You charge a battery, you do not refuel it.

Second, if it is being refueled, what is it being refueled with? Does it have a small fusion plant, and if so, why the need for a ship to refuel? All it should need is a source of Hydrogen.

If it is being recharged, and only needed this every ten weeks of operation, where is the battery pack for these incredibly efficient and lightweight batteries?

Last question, why is it not offered in an enclosed version?

 

[Whipsnade]

First, refueling does not strike me as the same as recharging. You charge a battery, you do not refuel it.

There are fuel cells which are refueled.

Second, if it is being refueled, what is it being refueled with?

Liquid electrolytes such as those found in RFC/Redox type fuel cells. The liquid in question needs to be reprocessed via an energy input.

Does it have a small fusion plant...

Not the CT version.

... and if so, why the need for a ship to refuel? All it should need is a source of Hydrogen.

It needs power from the ship to reprocess the liquid electrolyte within it.

If it is being recharged, and only needed this every ten weeks of operation, where is the battery pack for these incredibly efficient and lightweight batteries?

Not a battery pack. A fuel cell.

Last question, why is it not offered in an enclosed version?

It is. It's just called something else, just as how a SUV isn't called a sedan.

CT'81, LBB:3, starting on Page 22 under the Heading of Grav Vehicles you can read about the air/raft, GCarrier, and Speeder. The last two are enclosed.

The air/raft is straight out of the Dumerest series. It's meant to be a little utilitarian runabout much like the first jeeps. It barely reaches 60mph, doesn't handle the weather too well, and you can throw a tarp over the top if you want. If you want something more comfortable or capable, start earning the money to buy it!

 

[BlackBat242]

I suspect that the Air-raft is actually considered to be powered by a small drive using plasma fuel - hence the need to be refueled via a starship's power plant (or a ground-based power plant). It doesn't have a "Mr Fusion" plant, it has a set of plasma containment bottles*.

That's what makes sense to me, anyway.


As for the "open top", that's the most common (and cheapest) model - I have slightly more expensive enclosed models, more expensive pressurized models, and yes, even 6-ton & 8-ton models of all of the above.

The book's equipment lists are not a limit, they are a starting point!



* Don't let the bottles get shot!

 

[Whipsnade]

I suspect that the Air-raft is actually considered to be powered by a small drive using plasma fuel - hence the need to be refueled via a starship's power plant (or a ground-based power plant). It doesn't have a "Mr Fusion" plant, it has a set of plasma containment bottles*.

I like that. Consider it stolen.

The book's equipment lists are not a limit, they are a starting point!

Oh yes, very much so. That's the reason for the 1:1 1977 US dollar to Imperial Credit conversion. Apart from weapons, what are there maybe 60 items to buy in the LBBs? There needed to be a way for referees to quickly price all the other items their players would need/want to buy.

 

[Hyphen]

FWIW, I had a go at using Striker to create the ubiquitous TL 9 air/raft. Sorry Bill, I assumed it had a fusion pp.

trendi AirCar, TL 9 Air/raft (Striker)

Description: The AirCar has a crew of 1 (driver) and can carry up to 3 passengers. It mounts no weapons.

Statistics

Dimensions: Height: 1.3m Width: 3.0m Length: 4.5m (1.3 disp. ton)
Total usable volume: 12.3 cu m Weight: 8.35 tons (can float).

Price: Build, Cr144,000 (Sale, Cr500,000; Profit Cr356,000).

Movement: Max 360kmh/300cm, Cruise 270kmh/225cm, NOE 90kmh/75cm (loaded)
Max 1590kmh/1325cm, Cruise 1192kmh/993cm, NOE 130kmh/108cm (unloaded).
(Note that this theoretical speed is limited by a speed governor).

Armour: Front, 4; Rear, 3; Sides/Belly, 2 (no deck).

Target Size DMs: Low +2, no high hits.

Equipment: Nil.

Power: 1.1MW fusion power plant consumes 1.65 litres per hour, fuel capacity enough for 10 weeks 5 days at max (3000 l). Grav generators produce 11 tons of thrust, being 0.31Gs total.

Cargo: 4 cu. m (4000kg/4 tons).

Designer's Notes: this version is a lot faster than the original, but we're still only talking light aircraft speeds. Maybe (as Bill suggests) I should replace the power plant? At least I was able to get it to function for the canonical 10 weeks duration.
Even using a fusion pp, the original price is undercut by Cr456,000. Obviously the Vilani like their mark-ups.

[Taken from Tavonni Specialities ==> trendi ==> Vehicles ==> trendi AirCar]

 

[Enoki]

Unlike the rules, I generally have the air raft enclosed like a sedan, SUV, or minivan. The convertible version is the exception. Who would want one that's open topped for general use? That flies in the face of weather, temperature at altitude, atmosphere, and general comfort.
If you were paying the kind of cash necessary to purchase one I'd think most of the time you'd want one that is enclosed for comfort.

I also allow the enclosed ones to be pressurized meaning they can move much higher in a planet's atmosphere and even into low orbit. That makes them far more useful. They aren't for interplanetary or even trips to satellite worlds as this would take far too long and there are no "facilities" on an air raft for such a trip. But, you could do it if you were desperate or dumb as range is nearly unlimited in that sense.

The "speeder" I prefer to call a "gravcoupe" as it sounds more sporty and upscale. This version is like a high end sports car. It's much faster (sonic) and maneuverable than the family truckster...

Anyway, that's my view on them. Otherwise, they're much like the rules describe them.

 

[Timerover51]

FWIW, I had a go at using Striker to create the ubiquitous TL 9 air/raft. Sorry Bill, I assumed it had a fusion pp.

trendi AirCar, TL 9 Air/raft (Striker)

Description: The AirCar has a crew of 1 (driver) and can carry up to 3 passengers. It mounts no weapons.

Statistics

Dimensions: Height: 1.3m Width: 3.0m Length: 4.5m (1.3 disp. ton)
Total usable volume: 12.3 cu m Weight: 8.35 tons (can float).

Price: Build, Cr144,000 (Sale, Cr500,000; Profit Cr356,000).

Movement: Max 360kmh/300cm, Cruise 270kmh/225cm, NOE 90kmh/75cm (loaded)
Max 1590kmh/1325cm, Cruise 1192kmh/993cm, NOE 130kmh/108cm (unloaded).
(Note that this theoretical speed is limited by a speed governor).

Armour: Front, 4; Rear, 3; Sides/Belly, 2 (no deck).

Target Size DMs: Low +2, no high hits.

Equipment: Nil.

Power: 1.1MW fusion power plant consumes 1.65 litres per hour, fuel capacity enough for 10 weeks 5 days at max (3000 l). Grav generators produce 11 tons of thrust, being 0.31Gs total.

Cargo: 4 cu. m (4000kg/4 tons).

Designer's Notes: this version is a lot faster than the original, but we're still only talking light aircraft speeds. Maybe (as Bill suggests) I should replace the power plant? At least I was able to get it to function for the canonical 10 weeks duration.
Even using a fusion pp, the original price is undercut by Cr456,000. Obviously the Vilani like their mark-ups.

[Taken from Tavonni Specialities ==> trendi ==> Vehicles ==> trendi AirCar]

Hmm, you have room for 3 cubic meters of what I assume is Liquid Hydrogen, and 4 cubic meters of cargo. Where is the Liquid Hydrogen tank and the necessary insulation to keep it liquid? Your plant is using 1.65 liters of presumably Liquid Hydrogen an hour for a 1.1 Megawatt plant. I did some number crunching a while back on fission and fusion energy yields. I did use Deuterium, rather than standard Hydrogen.

The energy from the fusion of 235 units mass of Deuterium is equal to 582.8 MeV, or 2.914 times that of U-235 or Pu-239. The fission of 2 ounces or 57 grams of U-235 or Pu-239 will supply 132.4 kilowatts of power for every hour for a year. The fusion of an equivalent mass of Deuterium will supply 385.8 kilowatts of power for every hour of a year. To supply a constant power of 10 Megawatts for an entire year of 8760 hours would require the fission output of 151 ounces of U-235 or Pu-239 or 51.85 ounces of Deuterium.

For a 1.1 Megawatt output, for an entire year of continuous use, it would require the fusion of fractionally over 5.7 ounces of Deuterium. By the way, where are you getting rid of the very hot fusion plasma you are constantly creating while operational?

I have problems with the idea of very small fusion power units, because you have to have some way of converting the fusion energy into electrical energy to power things.

 

[aramis]

There are fuel cells which are refueled.



Liquid electrolytes such as those found in RFC/Redox type fuel cells. The liquid in question needs to be reprocessed via an energy input.



Not the CT version.



It needs power from the ship to reprocess the liquid electrolyte within it.



Not a battery pack. A fuel cell.



It is. It's just called something else, just as how a SUV isn't called a sedan.

CT'81, LBB:3, starting on Page 22 under the Heading of Grav Vehicles you can read about the air/raft, GCarrier, and Speeder. The last two are enclosed.

The air/raft is straight out of the Dumerest series. It's meant to be a little utilitarian runabout much like the first jeeps. It barely reaches 60mph, doesn't handle the weather too well, and you can throw a tarp over the top if you want. If you want something more comfortable or capable, start earning the money to buy it!

Traveller Fuel Cells are, like NASA fuel cells, combustion via catalysis cells consuming hydrogen and oxygen, producing water and electricity.

They are not "battery-like" - and they need to exhaust the steam that results. NASA does so into the potable tank...

 

[McPerth]

While working on a discussion in another thread, I went back to look at the data on the standard Air/Raft, and finally decided to ask about something that has bugged me for years. Per Supplement 8: Library Data (A-M), the following is stated regarding the Air/Raft.



First, refueling does not strike me as the same as recharging. You charge a battery, you do not refuel it.

Second, if it is being refueled, what is it being refueled with? Does it have a small fusion plant, and if so, why the need for a ship to refuel? All it should need is a source of Hydrogen.

If it is being recharged, and only needed this every ten weeks of operation, where is the battery pack for these incredibly efficient and lightweight batteries?

Last question, why is it not offered in an enclosed version?

In MT, where those things are more detailed, we can find 2 open air-rafts in 101 vehicles:

• #69: TL10. 0.75 Font displacement, 4 cramped seats. Powered by fuel cells, 4 days autonomy. KCr 295
• #97. TL15. 4 dton displacement. 7 roomy seats. Fusion powered, 60 days autonomy. KCr 275.

For a 1.1 Megawatt output, for an entire year of continuous use, it would require the fusion of fractionally over 5.7 ounces of Deuterium.

As I've Heard MT is based on Striker, I guess fuel consumption is the same (or at least not too different). If so, remember MT power plants are known by their ridicously inefficiency...

 

[atpollard]

As I've Heard MT is based on Striker, I guess fuel consumption is the same (or at least not too different). If so, remember MT power plants are known by their ridiculous inefficiency...

Sorry, I can't resist ...

"How efficient is YOUR sustained fusion power plant?"
I can't get a net surplus of energy from any of my attempts.

 

[McPerth]

Sorry, I can't resist ...

"How efficient is YOUR sustained fusion power plant?"
I can't get a net surplus of energy from any of my attempts.

I didn't say "Fusion Power Plants", but "Power Plants" in general...

If you need an example (in this case about fision power plants), see the ship shown in this thread (MT version, MgT one is only as comparison).

I don't expect fusion to be different (and neither do subsequent versions of Traveller). I don't know where did Timerover51 take his numbers about the deuterium needed, but he uses to show more knowledge than myself on most those matters,

 

[RandyB]

The book's equipment lists are not a limit, they are a starting point!

Oh yes, very much so. That's the reason for the 1:1 1977 US dollar to Imperial Credit conversion. Apart from weapons, what are there maybe 60 items to buy in the LBBs? There needed to be a way for referees to quickly price all the other items their players would need/want to buy.

And, having read through the CT Adventures and Double Adventures recently, many of them had additions to the equipment list relevant to the adventure. Mission on Mithril even included the Laser Pistol.

 

[atpollard]

I didn't say "Fusion Power Plants", but "Power Plants" in general...

If you need an example (in this case about fision power plants), see the ship shown in this thread (MT versión, MgT one is only as comparison).

I don't expect fusión to be different (and neither does subsequent versions of Traveller). I don't know where do Timerover51 take his numbers about the deuterim needed, but he uses to show more knowledge tan myself on most those matters,

I was mostly teasing.
I do the same thing ... apply some real world assumptions to an imaginary technology and draw conclusions about it's realism.

Like I said, I am guilty of the same thing. It is just still funny to hear about the 'inefficiency' of fusion compared to a 'theoretical value' when real people are working so hard to really achieve it and would do cartwheels of joy to achieve those results.

(I am probably just easily amused.)

 

[whartung]

Where is the Liquid Hydrogen tank and the necessary insulation to keep it liquid?

It sits on top of the right hand rear view mirror.

By the way, where are you getting rid of the very hot fusion plasma you are constantly creating while operational?

There's some Q-Tips crammed in the cigarette lighter to take care of this. Every 6 months you replace them with some of the extra Q-Tips stored in the non-locking glove box, behind the old mints and vintage AAA map (which just won't fold properly).

Ya know, going out on a limb, I'm betting that the designer applied the rules as written and came up with this design. Apparently the rules don't specify in detail how things such as L-Hyd is insulated or where excess heat is vented.

If you'll kindly point the tables out, then I'm sure they can be reincorporated in to the design.

Otherwise, I think it's fair to assume that since THIS IS A GAME, that it's a valid design and suitable for adventuring.

As I've mentioned in the past, most of Traveler is that things are powered with a light hum of minimal environmental impact rather than Joe Citizen running around with an H-Bomb on the brink of going critical, and accidentally lighting off continent wide wild fires when the vehicle passes to close to a tree or ignites the concrete with the blinky lights that it lands upon at the house.

 

[aramis]

In MT, where those things are more detailed, we can find 2 open air-rafts in 101 vehicles:

• #69: TL10. 0.75 Font displacement, 4 cramped seats. Powered by fuel cells, 4 days autonomy. KCr 295
• #97. TL15. 4 dton displacement. 7 roomy seats. Fusion powered, 60 days autonomy. KCr 275.

As I've Heard MT is based o nStriker, I guess fuel consumption is the same (or at least not too different). If so, remember MT power plants are known by their ridicously inefficiency...

Inefficiency inherited from Striker. It's the 250MW = 1 EP specified in striker that really kills things... not because it's any the worse than HG, but that more stuff uses power...

 

[Whipsnade]

FWIW, I had a go at using Striker to create the ubiquitous TL 9 air/raft. Sorry Bill, I assumed it had a fusion pp.

Great design! It's been greedily horded in my Black Hole of Quality.

I've no problem with fusion, I just took a stab at explaining the Library Data. It's always fun to try and make canon "work" rather than just shoehorn canon into a mental straightjacket while throwing out all those bits which don't fit some preconceived notion.

Traveller Fuel Cells are, like NASA fuel cells, combustion via catalysis cells consuming hydrogen and oxygen, producing water and electricity.

There are more real world fuel cell designs than those employed by NASA, so there will be more fuel cell designs in the OTU than the few shown in canon.

FF&S isn't the whole of current or "make-believe" technology.

 

[Enoki]

Exactly how much power one of these vehicles requires would be based on two things:

First, it has to produce enough to negate the weight of the vehicle loaded so it can float in whatever gravity is present. So, on Earth you'd need 1G of acceleration for the mass of the vehicle on the grav plates. This might have to be more than 1G if you are using the grav system to gain altitude rather than using lift.

Second, you have to have some amount of acceleration to drive the vehicle forward. This has to overcome the vehicle's drag in whatever atmosphere is present along with be sufficient for it to reach whatever speed it is intended to move at. Much like cars, this would depend on purpose. Something "sporty" would have to have better acceleration and top speed than something intended as a delivery van.

How much power that is...?

 

[Timerover51]

I don't expect fusión to be different (and neither does subsequent versions of Traveller). I don't know where do Timerover51 take his numbers about the deuterim needed, but he uses to show more knowledge tan myself on most those matters,

My apologies for not citing my source. It is The Effects of Nuclear Weapons, Compiled and edited by Samuel Glasstone and Philip J. Dolan ,Third Edition 1977. I have it in hard copy as a Department of Army Pamphlet. You can get the first few chapters, here.

http://www.abomb1.org/nukeffct/index.html

It covers the yield of both fission and fusion reactions.

 

[Timerover51]

Exactly how much power one of these vehicles requires would be based on two things:

First, it has to produce enough to negate the weight of the vehicle loaded so it can float in whatever gravity is present. So, on Earth you'd need 1G of acceleration for the mass of the vehicle on the grav plates. This might have to be more than 1G if you are using the grav system to gain altitude rather than using lift.

Second, you have to have some amount of acceleration to drive the vehicle forward. This has to overcome the vehicle's drag in whatever atmosphere is present along with be sufficient for it to reach whatever speed it is intended to move at. Much like cars, this would depend on purpose. Something "sporty" would have to have better acceleration and top speed than something intended as a delivery van.

How much power that is...?

One Kilowatt is equal to 3414 BTUs, and one BTU is equal to approximately 778 foot-pounds. Assuming not-quite perfect efficiency, then figure that one Kilowatt will lift 3,000 pounds to 750 feet above ground level on Earth. With an Air/Raft massing, loaded, at 8 metric tons or 17,636.981 pounds, to lift an Air/Raft to 750 feet will take about 6 Kilowatts. For every additional 750 feet, another 6 kilowatts will be required.

The forward speed of an Air/Raft is given at 100 Kilometers per hour, with some capable of 120 kilometers per hour, so about 62 to 75 miles per hour. That is about the top speed of some of the early biplanes, with a lot of drag producing wires, struts, and landing gear. The biplanes needed about 100 or so horsepower to achieve that speed. The Air/Raft might have a bit more frontal area for drag, so you might need somewhere around 150 or so horsepower to move it. One kilowatt is equal to 1.34 horsepower, assuming perfect efficiency. Allowing for inefficiency and drag, I will assume that an Air/Raft will need 150 to 200 kilowatts of power for forward motion.

It would appear that an Air/Raft will need a power plant capable of generating at least 24 kilowatts of power for every 900 meters of altitude capability, and at least 200 kilowatts for forward power. Drag will be less in thinner air and greater in denser air, so performance may vary based on the planet's atmosphere. For a 9000 meter altitude capability at 120 kph, it will require about 440 kilowatts of power. If you divert power from the forward propulsion plant to altitude, you can, of course, go higher.

 

[McPerth]

Exactly how much power one of these vehicles requires would be based on two things:

First, it has to produce enough to negate the weight of the vehicle loaded so it can float in whatever gravity is present. So, on Earth you'd need 1G of acceleration for the mass of the vehicle on the grav plates. This might have to be more than 1G if you are using the grav system to gain altitude rather than using lift.

Second, you have to have some amount of acceleration to drive the vehicle forward. This has to overcome the vehicle's drag in whatever atmosphere is present along with be sufficient for it to reach whatever speed it is intended to move at. Much like cars, this would depend on purpose. Something "sporty" would have to have better acceleration and top speed than something intended as a delivery van.

How much power that is...?

In this MT is ridcously efficient (I guess also inherited from Stiker), as grav needs less energy than the potential energy gained by the lift object. You can see the numbers in this thread (and maybe have some laughts at it).