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 four spinner weapons:
a simple bar spinner
a thick-walled drum spinner
a 'beater bar' spinner
an asymmetric 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.
Calculator Example: Asymmetric
Q: Hey, I want to build an asymmetrical beater bar weapon. I plan to use a Badass 1360 Kv motor, 21.6 voltage battery, and a 2:1 ratio gearbox. Can you guide me through using the team run amok spinner weapon calculator? I'm confused on how to use it to make an asymmetrical beater bar.
A: The Spinner Calculator lets you assemble and model a symmetric design from the geometric shapes available in the calculator, but an asymmetric design requires specialized center of mass and rotational inertia functions that the calculator cannot perform. You'll need a CAD program for that.
When you have your asymmetric weapon design, here's how to enter it into the calculator for modeling:
The CAD program you use to design your asymmetric beater bar will be able to provide the weapon Moment of Inertia.
Enter the Moment of Inertia into the Asymmetric: MOI field in the Weapon Elements section of the calculator and leave the other fields blank.
In the Brushless Weapon Motor section enter your 'BadAss' motor data:
Kv: 1360
Ri: 13 mΩ
Volts: 21.6
Reduction: 2 to 1
Click
The calculator will not have enough information to calculate Weapon Mass or Tip Speed but will give Weapon Speed and Kinetic Energy. Your CAD program can provide weapon mass, and if you want tip speed go back up to Weapon Elements and enter your weapon radius in the Impactors field, leaving the mass at zero.
