Atmospheric Reentry Heating Calculator
Aerothermodynamics: Model spacecraft atmospheric entry using the Allen-Eggers equations, peak g-load, deceleration altitude, and Sutton-Graves stagnation heat flux.
Entry Vehicle & Flight Path
Deceleration & Thermal Protection
Recommended Tools & Equipment
Tested hardware and components for high reliability
Frequently Asked Questions
Why do blunt heat shields experience lower heating than slender needles during reentry?
Discovered by H. Julian Allen in 1951, a blunt nose generates a detached bow shock wave far ahead of the vehicle. This bow shock dissipates 90% to 99% of the spacecraft's immense kinetic energy directly into heating the surrounding atmospheric air, leaving only 1% to 10% to conduct into the vehicle heat shield. Conversely, sharp slender cones keep the shock attached, pumping intense frictional heat directly into the skin.
What is the ballistic coefficient (β) and how does it determine reentry?
The ballistic coefficient β = m / (C_D * A) measures a vehicle's ability to overcome aerodynamic drag. A low-beta blunt capsule (β ~ 300-400 kg/m²) decelerates high in the tenuous upper atmosphere (60-80 km), spreading the g-forces and thermal load gently. A high-beta warhead (β > 2,000 kg/m²) plunges deep into the dense lower atmosphere before decelerating, experiencing extreme g-forces and brutal heat fluxes.
Why does a flight path angle change of just 1 degree have catastrophic consequences?
Peak g-load scales directly with sin(gamma). If entry angle is too steep (e.g. -7° instead of -2°), the vehicle penetrates dense air at hypersonic speed, generating lethal g-loads (>20 g) and thermal fluxes that overwhelm the TPS. If the angle is too shallow (e.g. > -1.0°), the vehicle skips off the upper atmosphere like a stone across a pond, stranding the spacecraft in an uncontrolled orbit.