JSBSim L-4S-5 Flight Simulation
Based on digitized data from the orginal paper a JSBSim model is built and run. Here we compare the simulation results to charts in the technical papers.
Download a copy of the Lambda-4S JSBSim configuration:
Table of Contents:
- Mass Table
- First Stage Thrust
- First 5 km Altitude/Downrage Plot
- First Stage Performance
- Second Stage Performance
- Third Stage Performance
- Combined 1st–3rd Stage Performace
Mass Table
This is the mass and moment of inertia table output by JSBSim’s initialization report:
| Vehicle Component | Weight [kg] | CG-X [m] | CG-Z [m] | Ixx [kg·m²] | Iyy [kg·m²] | Izz [kg·m²] |
|---|---|---|---|---|---|---|
| Base Vehicle | 23.0 | 0.556 | 0.000 | 0.3 | 0.4 | 0.4 |
| 0 Nose Faring | 10.0 | 0.500 | 0.000 | 2.6 | 2.2 | 2.2 |
| 1 3rd Stage | 273.9 | 1.941 | 0.000 | 69.6 | 235.2 | 235.2 |
| 2 2nd Stage | 619.4 | 5.999 | 0.000 | 334.6 | 978.0 | 978.0 |
| 3 Right Booster | 190.5 | 13.401 | 0.523 | 18.3 | 538.0 | 538.0 |
| 4 Left Booster | 190.5 | 13.401 | -0.523 | 18.3 | 538.0 | 538.0 |
| 5 1st Stage | 1089.4 | 12.329 | 0.000 | 588.6 | 6671.0 | 6671.0 |
| 0 Solid Fuel | 312.0 | 13.400 | 0.523 | 16.6 | 874.5 | 874.5 |
| 1 Solid Fuel | 312.0 | 13.400 | -0.523 | 16.6 | 874.5 | 874.5 |
| 2 Solid Fuel | 3887.0 | 12.000 | 0.000 | 1127.7 | 21294.5 | 21294.5 |
| 3 Solid Fuel | 1845.0 | 5.000 | 0.000 | 535.3 | 2727.6 | 2727.6 |
| 4 Solid Fuel | 547.5 | 2.000 | 0.000 | 80.5 | 770.2 | 770.2 |
| 5 Solid Fuel | 88.0 | 0.500 | 0.000 | 10.1 | 6.8 | 6.8 |
| Totals: | 9388.2 | 9.393 | 0.000 | 3093.2 | 185157.8 | 184883.4 |
First Stage Thrust
Total thrust of the first stage and strap-on boosters compared to the published L-4S-2 vehicle data.
The differences here are likely becuase of a couple of factors. I tried to use data that best fit the L-4S-5 vehicle, but here we’re compairing to L-4S-2. They should be pretty similar, but are many years apart. Secondly there is going to be a difference in the approximate sea-level thrust and the actual thrust JSBSim will compute based on altitude and nozzel expantion ratio.
First 5 km Altitude/Downrage Plot
The trajectory paper included several downrange vs altitude charts. The difference cases are for a variaty of launch angles. This should define an expected operating envelope for our vehicle.
First Stage Performance
The first stage, though burnout compared to the flight overview numbers.
Second Stage Performance
Third Stage Performance
Combined 1st–3rd Stage Performace
