BeastPower Defined

[Timerover51]

I put this up on another thread, but because it does give a way to determine exactly how much power is 1 BeastPower, I thought that a separate thread might get more visibility.

From T5.0.9 rules, page 254, bottom right-hand corner.

On the chart, human output ranges from 0.01 to 0.03 BP depending on Speed.

From Wikipedia, the following human to watt output is given, which seems about right. The information is from the Marks' Standard Handbook for Mechanical Engineers 11th Edition , Mc-Graw Hill, New York 2007

Over an 8-hour work shift, an average, healthy, well-fed and motivated manual laborer may sustain an output of around 75 watts of work.[2]

One Horsepower is equivalent to 745 watts, so a human could be rated at one-tenth a horsepower output. This means that Traveller rates a human at about one-fiftieth of a Beastpower at 0.02 on the average. Cranking the number through, that means a Beastpower is equal to 5 horsepower.

Confirming that this is about correct is the following quote, again from Page 254, bottom right-hand corner.

For beasts and beast-drawn vehicles, 1 ton (a measure of volume) is also 1000 kg in a wheeled cart on level ground.

Based on the chart on the page, it takes 1 BeastPower to haul a wheeled cart/wagon loaded with 1 mass ton of material at 5 kilometers or 3 miles per hour. From a wide range of sources including Garnet Wolseley's Soldier's Pocket Book and various U.S. Army manuals, a wagon holding a ton on took between 4 and 6 horses or mules to haul it on level ground. This again gives a result of 1 BeastPower is equal to 5 Horsepower.

Therefore, when it comes to power, 1 BeastPower is equal to 5 Horsepower or putting it into Kilowatt terms, 1 BeastPower is equal to 3725 watts, or 3.725 Kilowatts.

Now, when it comes to weight, a very highly developed aircraft internal-combustion engine from World War 2 could generate about 1 horsepower per pound of engine. That was the peak output, and could be sustained for no more than 5 to 15 minutes without damaging the engine. Sustained output would be half of that. Diesels are going to weight about twice that in a lightweight aircraft Diesel. That would be the weight of the engine, and does not include the power train to get the output to where is it used.

For steam power plants, you have to figure on the volume of the boilers as well as either the steam reciprocating engine or the turbine, with or without reduction gear for the turbine. No reduction gear means either that the turbine is running very slowly if being used to power a ship, with a corresponding increase in size and mass, or the screw is running at an inefficient high speed and wasting power. One reason that the U.S. Navy retained reciprocating engines for its battleships longer than most countries was the range requirement for Pacific operations. At lower cruising speeds, the reciprocating engine was more efficient in fuel use. The U.S. Navy had also taken the reciprocating engine to a very high state of development, so that it could be run at a high power output for a sustained time without excessive engine wear and tear. The conversion from coal to bunker grade fuel oil helped with the range issue by roughly halving the weight of fuel burned per horsepower-hour. The conversion from coal to oil also considerably reduced manning requirements in the engine room. If you are designing a steam-powered ship fueled with coal, you need to allow for stokers for the boiler room and stokers to move coal from distant bunkers to the ready-use bunkers by the engine room. Then there is also the time required to coal the ship.

I hope that all of this is a help to someone, and I do have a fair amount of data on engines of various types, along with steam power plants for ships. There are also some quite simple rules of thumb for determining power requirement for conventional aircraft and helicopters, along with ships.

 

[Ulsyus]

Impeccable work Timer.

While I may not need it now, someone will and I'll likely need this at some point, so I reckon your efforts will go to good use in someone's campaign. Top job!

 

[OjnoTheRed]

Great work - yes, that will certainly come in useful somewhere when pondering scaling of energy somewhere.

 

[AnotherDilbert]

Yes, this is what the system says. But, like the rest of the VehicleMaker system, it gives completely unreasonable results.

Example: A bog standard Wheeled Car: TL-6, 2 Dt, Speed 5 has, according to the table 250 BeastPower, which would be 1250 hp.


I would say that BeastPower is better left undefined, as to not strain our credulity unduly.

 

[Sebastion Russ]

Displacement Tons

To be fair to the vehicle maker, 2 Dt would be an 8ft by 8ft by 16ft vehicle. If my car had those dimensions, I would be pissed if it could not hit 1200hp.

A standard car is closer to 5ft wide by 4ft high by 10ft long. a 8x8x16 would be closer to a (very) heavy pickup truck.

 

[AnotherDilbert]

To be fair to the vehicle maker, 2 Dt would be an 8ft by 8ft by 16ft vehicle.

As I said, unreasonable results...

If my car had those dimensions, I would be pissed if it could not hit 1200hp.

I doubt it...

Truck, 13-16 litre engine, 370-730 hp, Torque 2000-3500 Nm.

Even large road trucks don't have or need over 1000 hp. Especially in the 60's (TL-6).

 

[Timerover51]

To be fair to the vehicle maker, 2 Dt would be an 8ft by 8ft by 16ft vehicle. If my car had those dimensions, I would be pissed if it could not hit 1200hp.

A standard car is closer to 5ft wide by 4ft high by 10ft long. a 8x8x16 would be closer to a (very) heavy pickup truck.

A couple of vehicle examples. All data taken from U.S.Army vehicle manuals.

A 1951 Cadillac ambulance, 246 inches long by 81 inches wide by 75 inches high, gross weight of 7220 pounds, had a recommended top speed of 65 miles per hour, and had a 141 horsepower engine at peak output for power. It had a crew of 2 and could carry 10 passengers.

A World War Two 2.5 ton amphibious DUKW 6 X 6, 372 inches long by 96 inches wide by 106 inches high, with a gross weight loaded of 19,850 pounds, had a 104 horsepower engine. The recommended top speed on roads was 50 miles per hour. The cargo capacity was 2.5 tons, 5000 pounds, and it had a crew of 2.

I have not tried to put either of these vehicles through Vehicle Maker. If someone wants to, feel free to do so.

 

[Timerover51]

I put the DUKW through Vehicle Maker Beast Power determination using both volume in dTons and straight mass. The volume is dTons is 7, while the mass in metric tons is slightly over 9, so I used 9. The speed of 59 miles per hour equates to 80 kilometers per hour, so between the 50 and 100 kilometers per hour of the chart.

For 7 dTons of volume, the Beast Power chart gives me a required power of between 875 and 1512, so figuring the 80 kilometer per hour speed at six-tenths of the difference between those two numbers, I get 1257 Beast Power needed.

For 9 tons of mass, the range between 50 and 100 kilometers per hour is 1125 and 1944. Again figuring six-tenths of the difference between the two, I get 1616 Beast Power needed. Actual horsepower of the DUKW was 104, or just about 21 Beast Power, treating 1 Beast Power as equal to 5 horsepower. The Beast Power requirement overstates the actual horsepower needed by between 60 and 80. That is a fair overstatement.

I did a quick approximation for the M3 Stuart Light Tank at 28,000 pounds or 12.7 metric tons, and capable of hitting 36 miles per hour, equivalent to 58 kilometers per hour. As it is an armored vehicle, +2 is added to the speed column, so the required Beast Power for 50 kilometers per hour is 4459 or 22,295 horsepower. The actual engine horsepower used was 242. The required horsepower is overstated by a factor of 92.

As the Beast Power formula for peak output is Tons (it looks like either mass tons or volume dTons can be used) times a Speed Number to the Third Power, I am not sure I want to figure out the Beast Power required for an Iowa-class Battleship at 52,000 tons loaded and easily capable of over 50 kilometers per hour at that loaded figure.

Edit Note: As horsepower is a measurement of mass being moved and not volume, Beast Power should be computed the same way. Power is not moving volumes, but moving mass.

 

[AnotherDilbert]

I put the DUKW through Vehicle Maker Beast Power determination using both volume in dTons and straight mass. The volume is dTons is 7, while the mass in metric tons is slightly over 9, so I used 9.

The VehicleMaker system uses volume:

Tons is the calculated Volume Tonnage.

 

[Timerover51]

Here are a couple of rules of thumb when it comes to horsepower needed for armored vehicles and propeller-driven aircraft.

For Armored Fighting Vehicles, AFV, less than 5 horsepower a ton makes if barely moving, while 5 to 10 horsepower per ton makes it a slow mover. Over 10 horsepower per ton gives it reasonable agility, while over 15 horsepower per ton makes it quite agile, assuming adequate suspension and track width.

For propeller-driven aircraft, an aircraft could take off with a ratio of 15 pounds of aircraft total weight per 1 horsepower of take off power. A lot of aircraft engines had a take off rating that could be maintained for between 5 to 15 minutes. You could take off with a heavier load if you had a long enough runway, and did not have to gain altitude very fast. This does assume near sea-level conditions. Higher altitudes, or in the case of Traveller, a Thin atmosphere would reduce take off weight due to reduced lift. Dense atmosphere would allow for heavier take off weights, but reduce top and cruising speed due to increased drag.

Now, remember, these are rules of thumb for first approximations of power required. You will find vehicles that are outside of these ranges, some by quite a lot. The final power required depends on the complete design, were power is just one part.