Oberth Specific Energy Comparison
Compare specific orbital-energy gains from the same instantaneous prograde burn at two supplied speeds.
Description
The same prograde impulse produces a larger specific energy gain when applied at a higher initial speed.
The same prograde impulse produces a larger specific energy gain when applied at a higher initial speed. This local energy comparison illustrates the Oberth effect without propagating a transfer.1
Compare specific orbital-energy gains from the same instantaneous prograde burn at two supplied speeds.
When to use Oberth Specific Energy Comparison
Use this tool to compare specific orbital-energy gains from the same instantaneous prograde burn at two supplied speeds.
Prepare the orbital state or model parameters in one reference frame. Confirm compatible distance/time units and the stated angular and gravitational-parameter conventions.
How to use Oberth Specific Energy Comparison and understand its results
- Prepare the orbital state or model parameters in one reference frame. Confirm compatible distance/time units and the stated angular and gravitational-parameter conventions.
- Enter periapsisSpeed, comparisonSpeed, progradeDeltaV using the field table and calculation rules, then run the tool.
- Read periapsisEnergyGain, comparisonEnergyGain, energyGainMultiplier. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| periapsisSpeed | Periapsis speed | number | Required |
| comparisonSpeed | Comparison speed | number | Required |
| progradeDeltaV | Prograde delta v | number | Required |
Enter nonnegative periapsis and comparison speeds in a common unit and a positive prograde deltaV. The tool calculates both energy gains in squared speed units and their ratio. Equal speeds produce a multiplier of one; the label periapsis does not force that speed to be greater.
energyGain = speed × deltaV + deltaV²/2 Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| periapsisEnergyGain | Periapsis energy gain | number |
| comparisonEnergyGain | Comparison energy gain | number |
| energyGainMultiplier | Energy gain multiplier | number |
{
"input": {
"periapsisSpeed": 30,
"comparisonSpeed": 10,
"progradeDeltaV": 2
},
"output": {
"periapsisEnergyGain": 62,
"comparisonEnergyGain": 22,
"energyGainMultiplier": 2.8181818181818183
}
}Limitations and assumptions
Both burns are instantaneous and aligned with motion. The calculation does not determine periapsis, propellant, transfer geometry or attainable burn locations.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Powered Flyby Velocity Budget: Budget a local powered-flyby velocity vector change and specific kinetic-energy change from supplied periapsis speeds and angle; no B-plane trajectory is solved. For a complementary task, use Hohmann Transfer Budget: Compute both coplanar Hohmann burn magnitudes, total impulse, and half-period coast time for circular endpoints.
References
-
Oberth Specific Energy Comparison — tool.io
Similar or alternative tools
- Powered Flyby Velocity Budget
Budget a local powered-flyby velocity vector change and specific kinetic-energy change from supplied periapsis speeds and angle; no B-plane trajectory is solved.
- Hohmann Transfer Budget
Compute both coplanar Hohmann burn magnitudes, total impulse, and half-period coast time for circular endpoints.