Quantify error due to ablation

[cmflannery]

Determine if error due to throat ablation can be ignored in CFD analysis. Baseline Q-class motor using APCP fuel.

[cmflannery]

• Ablative Cooling Study

Regression due to ablative cooling can be estimated with this plot and the chamber pressure. Ablation is only estimated at the throat (graphite).

Chamber pressure ~= 4.815 MPa Burn time ~= 7.5 s

• from motor calc sheet

Estimated graphite regression ~= 0.17 mm/s

• based on chamber pressure & plot above

Total estimated regression ~= 0.17 mm/s * 7.5s = 1.275 mm

[cmflannery]

Closing as "won't fix" - Ablative cooling for such a short burn time does not result in significant loss of thrust due to throat area increase.