What Fusion Power means to the Project

[tsofian]

The original designers incorporated fusion power so teams would not need to chase fuel all the time. As with a lot of decisions they made there are a number of unintended consequences that cascade from this

First, you can use fusion to power your tunnel boring machines an they become the fabulous subterrenes that UFO/Secret Underground Base folks talk about. There are US Patent documents concerning these machines from the early 1970s so it is quite possible the Project had them nearly as soon as they got fusion.
It can also provide long lasting power to bases. Bases are going to need large power generators, so fusion is ideal. Having what basically amounts to unlimited energy
If this Lockheed reactor is used as the base for the big units at the bases there is little you can’t throw raw energy at.
The prototype was planned to be a 100-megawatt deuterium and tritium reactor measuring 7 by 10 feet (2.1 by 3.0 m) that could fit on the back of a large truck and would be about one tenth the size of current reactor prototypes. 100 megawatts is enough to provide power for 80,000 people.[2][14] A series of prototypes were constructed to approach this goal.
TX Reactor[edit]
Parameters:
• 7 m diameter × 18 m long, 1 m thick blankets
• 320 MW gross
• 40 MW heating power, 2.3 s
• n = 5×1020 m−3
• β = 1 (field = 2.3 T)
• V = 16.3 m3, 51 MJ total energy
• Ti = 9.6 keV
• Te = 12.6 keV

Water can be distilled or cleaned with reverse osmosis. Non-recyclable trash can be incinerated. Any hazardous chemicals except radiological and heavy metals can be ionized into simple elements. I’d assume each base would have redundant fusion plants


How much would a bolt hole need?

Here is my guess. Each Freeze tube needs 2 kW of power to maintain its temperature. Warming would need a much higher peak load so let’s say the standard 8 person hole could cruise on 30 kW and would peak at 100 kW during wake up.
A mention was made of using Radioactive decay heat in the form of RTGs for powering bolt holes. The only really good isotope for this is Pu 238. https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator
Given the energy densities of this material it would require over 100 kilograms of this material per bolt hole for peak energy demand. Batteries could help with this, but even at “cruise” power demand 2,000 bolt holes require far more Pu238 than has ever been manufactured (Pu239 is far more common).
This fusion plant isn’t too much bigger than a vehicle one.

[dragoon500ly]

Couple of questions...

What is the projected life-span of the two units? Would they require periodic refueling are would they be good for, say a 200 year life span?

[mmartin798]

The original designers incorporated fusion power so teams would not need to chase fuel all the time. As with a lot of decisions they made there are a number of unintended consequences that cascade from this

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.
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TX Reactor[edit]
Parameters:
• 7 m diameter × 18 m long, 1 m thick blankets
• 320 MW gross
• 40 MW heating power, 2.3 s
• n = 5×1020 m−3
• β = 1 (field = 2.3 T)
• V = 16.3 m3, 51 MJ total energy
• Ti = 9.6 keV
• Te = 12.6 keV

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.
.

How much would a bolt hole need?

Here is my guess. Each Freeze tube needs 2 kW of power to maintain its temperature. Warming would need a much higher peak load so let’s say the standard 8 person hole could cruise on 30 kW and would peak at 100 kW during wake up.

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.
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This fusion plant isn’t too much bigger than a vehicle one.

Just a question to clarify something for me. When you say "This fusion plant isn’t too much bigger than a vehicle one," what are you referring to? The T4B experiments resulted in the TX being physically as large as it is, large enough to park 6 V-150s inside, to (theoretically) produce 320MW. The output of a "standard" size vehicle reactor has to be around 150KW. Your bolt hole calculations make that reactor needing to output only about 150KW to be safe, so is the output the size you are refering to?

[tsofian]

The bolt hole plant needs to produce about the same energy as a vehicle power plant, not the same size as the big plants for the bases

[mmartin798]

With the 4e timeline and potential for other vehicles, we may have to reevaluate what is a "standard" vehicle reactor. I am of a mind that they created a standard size for classes of vehicles to maximize the economy of scale in manufacturing.

In 3e, you could easily standardize on a 150KW for V-150's and smaller, 500KW for small aircraft like Bell 206 and OV-10, and a 3MW for larger aircraft like C-130 and CH-47 as well as smaller ships. This would supply power in the same range as their conventional counterparts.

But if we look at more modern versions of the Commando vehicles(1) and HEMTT that could be used in 4e, they are pushing upwards of 300-350KW power plants even with the diesel-electric hybrid HEMTT A3. We could still use the same standard sizes from 3e if we assume these newer vehicles use two reactors, much like a Project C-130 would have to house four 3MW reactors to match the conventional power. But this begs the question, can you fit in two reactors? There is clearly a minimum size and I assume that the physical size does not grow linearly with output, but rather is some kind of logarithmic increase in size. So in my world, a 300KW reactor would not be twice as large as a 150KW reactor.

So what is a "standard" vehicle reactor?
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(1) The Commando Select, which comes in configurations similar to the V-150, is slightly larger and is part of the reason I assume the power plant is larger. The Commando Select is 6.63m long, 2.74m wide and 3.02m tall and has a higher ground clearance at 0.66m. It has a higher max road speed of 100km/h and a larger turning radius of 10.65m. Handles the same 60% grade and has a slightly less vertical obstacle of 0.56m.

[cosmicfish]

One of the reasons I always used GURPS to actually play the game was because there is a Vehicles supplement that lets you design from the ground up. I built an entire fleet of compatible vehicles, very convenient and well balanced.

[tsofian]

The full size fusion plants are 100 mW for 200 tons. So 2 tons to the mW. The WW2 era Packard Merlin produced 1400 hp and weighed 1600 pounds dry. Between oil and antifreeze and other fluids, not to mention gasoline I can see a "Standard" fusion power pack running 500 horsepower or around 400 kW running at 2 tons or so.

If there is too much power in a particular vehicle it can be used to run other devices and such.

This is a very rough guess, based on far too little research

[cosmicfish]

If the intention is to use the fusion plant in place of the diesel motors generally found in military vehicles of these types, then (fusion plant + fuel storage) must be <= (diesel engine + transmission + diesel fuel and tank). If the goal is to use a single fusion plant for multiple vehicles then it must be smaller still, to allow for form factor issues, although some clever engineering can help as well - if you can divide the power system into subsystems, you may be able to reconfigure the system chassis without actually needing different functional components. But if your replacement fusion system exceeds either the volume or weight envelopes of the original then performance may be impaired, perhaps severely.

And regardless, aviation engines are a poor comparison. They are relatively high horsepower, low torque, with maintenance requirements that would be totally unacceptable for an exploratory ground vehicle. The diesel engine in the V-300 I know weighed a little less than a ton and produced only 260 or so HP... along with over 600 lb-ft of torque. The fuel tank was only around 600lb, if I recall correctly, but when you add the transmission 2 tons would probably be a reasonable total SWaP estimate for the V-300, with the V-150 presumably scaled to about half of that.

[Gelrir]

The engine, transmission, batteries, fuel tank, engine oil tank, and radiator of a V-150 weigh 1400 kg (the engine is the same as on early M113 armored personnel carriers). This is presumably replaced with the fusion generator, its fuel supply, an electric motor, and possibly a different radiator (depending on how you envision the reactor working).

--
Michael B.

[mmartin798]

It's probable that there would be one electric motor per axle. That is was the HEMTT A3 had and is still what Oshkosh uses on vehicles using the same PowerPulse diesel-electric drive. That would make the reactor the single point of failure, not the motor.

http://www.trucktrend.com/cool-trucks/1107dp-diesel-electric-hybrid-hemtt-oskosh-a3/

[ChalkLine]

Many of the concept designs have one electric motor per wheel hub. This lowers the sprung weight and means your power supply doesn't dictate how far your suspension travels.

[tsofian]

A quick look says electric motors are really massive

[ChalkLine]

Yep, it's a trade off. It's also a good, mature technology though.

How widespread are these fusion reactors just before the apocalypse? Really, keeping them purely for after-disaster teams just to retain an edge is a terrible crime

[mmartin798]

For comparison, let's just replace the Cat C15 diesel in the HEMTT A4 with a 500HP BALDOR 3PH Motor. Both generate 500HP, the C15 at about 2000 RPM and the BALDOR at 3600 RPM. The C15 engine without any of the exhaust treatment gear attached is 49in tall and 57 in long. The BALDOR is 40in tall and 67in long. The C15 dry weight tips the scales at roughly 3500 lbs, the BALDOR has a shipping weight (couldn't find the comparable dry weight) of 4780 lbs. So it is about a half ton heavier and almost a foot longer, but you gain a lot of head space.

[Gelrir]

An electric vehicle doesn't need the same horsepower as an internal combustion engine for the same performance; in some modern high-performance electric cars, they get by with about half the rated horsepower of an internal combustion-engined car.

For example:

https://youtu.be/6YuTpPr3Uv0

and:

https://auto.howstuffworks.com/how-does-horsepower-figure-into-electric-cars.htm

"Remember, the Tesla Roadster S is about as fast as a Corvette Z06 with almost half its horsepower."

So I don't think the correct "conversion" (for identical performance) is to swap in an electric motor of the same horsepower.

--
Michael B.

[nuke11]

You should be researching in-hub electric drive motors. These are the current trend in hybrid electric wheeled AFV's. They have also been tested for tracked vehicles as well.

They replace a standard AFV wheel hub. They are based on a 100kW continuous traction motor with a liquid cooled brake inside the hub.

Also from about 8 years ago the E-Drive Stryker is a good research project as well.

[mmartin798]

Felt obligated to do the math and stuck with the HEMTT A4, since I have all the specs I need for the calculations. Looking at maximum torque at the wheels; taking into account the engine torque, transmission and transfer case gear ratios; we get a total torque at the wheels of 15 252 Nm or 1906 Nm per wheel, since you can just divide it if you are assuming straight line thrust.

Looking at some Moog DB-22000 series motors, this puts us right in the middle of the pack. If we go with a DB-22000-E at each wheel, we get 2539 Nm of torque in a package that is 181 lbs and measures 5" in diameter and is 5.15" long. Since this is a frameless motor, we can add about another 5" or so for the frame, cooling system and other monitoring and diagnostic components and still fit inside the 17" rim with room to spare. If we assume the mass of each motor goes up to 250 lbs each, we only top out at 2000 lbs, which is about 1000 lbs less than the diesel it would replace.

Since the HEMTT A4 has the same performance specs, twice the axels and twice the mass of a V-150, the motors for a V-150 would probably be the same size with a proportional weight savings.

[nuke11]

I'm under 2 lines of thought for fusion conversion of a vehicle at the moment, leaning towards option I.

Option I conversion: simply take out the internal combustion engine and add fusion power source, electric motor and conversion plate to the existing transmission and drive train. Quick and simple conversion that does not require major alterations to the vehicle.

Option II conversion: this one is based on in-hub electric drive motors at all wheels. Take out the internal combustion engine, transmission and most of the drive train. Modify the wheel hubs and suspension.

Note: "Fusion power source' would include inverter(s), possible storage batteries.

[tsofian]

I like the idea of going whole hog and using hub motors.

I assume there is some battery power available, but since the fusion plant runs all the time there is less need for them. I'd say that one thing all Morrow vehicles include is an electrical patch panel that allows the many hookups that could be valuable