The Spinner Calculator Help File describes the functions and operation of the calculator, but it is useful to have a few examples to follow.
Below are example analyses for three spinner weapons:
a simple bar spinner
a thick-walled drum spinner
a 'beater bar' spinner
Calculator Example: Simple Bar
A bar spinner is simple and robust. It is also easy to enter into the calculator.
We enter the following values into the 'Bar' row in the Weapon Elements section of the calculator:
Density: 7800 [the density of steel]
Width: 90 mm [3.5 inches]
Thick: 16 mm [5/8" inch]
Length: 500 mm [20 inches]
Pressing shows that the weight of the weapon is 5.6 kilograms [12.5 pounds].
With the default weapon motor settings [AmpFlow F30-150 motor at 24 volts with a 3:1 reduction] the weapon will spin up to a tip speed of 52 m/sec [116 MPH] with about 2600 joules of stored energy, reaching 2300 joules in 2.6 seconds.
Calculator Example: Thick Drum
A Minotaur-style drum is a single thick-walled tube with split impactors. The mass of the impactors must be calculated separately and added in at the corect distance from the rotation axis.
We start with the impactors by entering the following values into the 'Bar' row in the Weapon Elements section of the calculator to find the impactor weight:
Density: 7800 [the density of steel]
Width: 50 mm [2 inches]
Thick: 50 mm [2 inches]
Length: 200 mm [8 inches]
Pressing shows that the bar weighs 3.9 kilograms [8.6 pounds].
Press to clear the bar entries.
Next we enter the following values into the 'Tube' row of the calculator:
Density: 7800 [the density of steel]
Rad 1: 76 mm [outer radius 3"]
Rad 2: 25 mm [inner radius 1"]
Length: 200 mm [8 inches]
Pressing shows that the tube weighs 25 kilograms [55 pounds].
Now we add the previously calculated mass of the bar into the 'Impactors' row of the calculator:
Mass: 3.9 kg [total mass of impactors]
Radius: 102 mm [impactor mass center - about 4"]
Pressing shows that the combined weight of the weapon with impactors is 29 kilograms [64 pounds].
With the default weapon motor settings [AmpFlow F30-150 motor at 24 volts with a 3:1 reduction] the weapon will spin up to a tip speed of 21 m/sec [47 MPH] with about 2600 joules of stored energy, reaching 2300 joules in 2.6 seconds.
Calculator Example: Beater Bar
A rectangular 'Beater Bar' is tricky to calculate because it is a combination of four elements: two 'bars' and two long 'impactors'.
We start by entering the following values into the 'Bar' row in the Weapon Elements section of the calculator to find the weight of two impactors:
Entering two 12" long by 1" square steel 'Impactors' into the calculator:
Density: 7800 [the density of steel]
Width: 25.4 mm [one inch]
Thick: 50.8 mm [double thick = two impactors]
Length: 300 mm [12 inches]
Pressing shows that the two impactors weigh about 3 kilograms [6.8 pounds].
Next we enter the dimensions of the two bars in the 'Bar' row by leaving the width and thickness values alone and shortening the length to match the bars:
Density: 7800 [the density of steel]
Width: 25.4 mm [one inch]
Thick: 50.8 mm [double thick = two bars]
Length: 200 mm [8 inches]
Finally we enter the weight of the two impactors and the radius to their center of mass into the 'Impactors' row :
Mass: 3 kg [6.8 pounds]
Radius: 89 mm [3.5 inches]
Pressing shows that the total weight of the beater is 5 kilograms [11 pounds].
With the default weapon motor settings [AmpFlow F30-150 motor at 24 volts with a 3:1 reduction] the weapon will spin up to a tip speed of 21 m/sec [47 MPH] with about 2600 joules of stored energy, reaching 2300 joules in 2.6 seconds.
I'll mention that a weapon this size made from 1" square bar is very 'spindly' -- I would expect it to be made of thicker and wider material.
