Compare two possible overall speed increases for a two-stage windmill drive. Both alternatives share the first-stage ratio you enter; the calculator shows the second-stage ratio required for each.
Windmill Form 2 Interactive Calculator
Enter sail RPM, two total step-ups and a shared first-stage ratio. The tool reports ideal speeds and implied stage-two ratios; it does not select tooth counts or model losses.
Equation Used
- Entered ratios are output/input speed magnitudes.
- Low and high totals are sorted numerically.
- Stage one is shared by both alternatives.
- All stages are rigid and lossless.
- Tooth counts, efficiency, wind power, load and structure are omitted.
Two-Stage Alternative Ratio comparison
The visual uses connected tangent pitch circles for one shared first stage and two labeled alternative second stages.
What This Calculator Represents
Two ideal total-ratio alternatives factored through one entered first stage.
Ratio Factoring
Rhi=max(Ra,Rb)
N=NsailR
R2=R/R1
Worked Scenario
At 12 rpm, totals 6.6667 and 8.3333 with R1=2, outputs are 80 and 100 rpm and implied second stages about 3.33 and 4.17.
Assumptions and Limits
No tooth selection, shaft loads, losses, wind power or millstone performance is calculated.
Frequently Asked Questions
Are inputs always low then high?
The calculator sorts them.
Is stage two designed?
No; only its ratio is inferred.
Are losses included?
No.
Are both paths simultaneous?
No; they are alternatives.
Is sail speed predicted?
No.
Can this design gearing?
No.
References
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