Isar Aerospace Spectrum: Orbital Flight Trajectory & Staging Flight Control

MISSION PARAMETERS STAGE 1 + 2

ORBITAL PROFILE

PITCH KICK ALTITUDE 1.2 km

PAYLOAD MASS 700 kg

STAGE 1 THROTTLE TRIM 100%

SIMULATION CLOCK RATE

STAGE 1 AQUILA PROPULSION

ENGINES: 9x Aquila SL (Propane / LOX)

SEA LEVEL THRUST: ~750 kN (83.3 kN ea)

VACUUM THRUST: ~850 kN

PROPELLANT: Bio-Propane + Liquid Oxygen

STAGE 2: 1x Aquila Vac (~95 kN, restartable)

Altitude 0.0km

Inertial Velocity 0m/s

Downrange Dist 0.0km

Dynamic Press (Q) 0.0kPa

Pitch Angle 90.0°

Acceleration 1.00g

Apoapsis / Periapsis 0 / -km

SPECTRUM STACK // SCHEMATIC

DIAMETER2.0 m

HEIGHT28 m

GLOW (MASS)~52,000 kg

STAGE 1 PROP100.0%

STAGE 2 PROP100.0%

STAGE STATES1 ARMED

MISSION SEQUENCING // MILESTONES

T+00:00 Liftoff (9 Aquila SL)
T+00:15 Pitch Kick & Gravity Turn
T+01:12 Max-Q (Dynamic Pressure)
T+02:24 MECO (Stage 1 Cut-Off)
T+02:27 Stage 1 Separation
T+02:30 Stage 2 Ignition (Aquila Vac)
T+03:15 Payload Fairing Jettison
T+08:50 SECO-1 (Transfer Orbit)
T+45:00 SECO-2 Orbit Circularization
T+52:00 Spacecraft Separation

Sovereign European Access to Space

Munich-based Isar Aerospace developed the Spectrum launch vehicle to give Europe independent, responsive, and flexible commercial orbital launch capabilities. Flying out of Andøya Spaceport in northern Norway (69.3° N), Spectrum directly serves polar, sun-synchronous (SSO), and highly inclined orbits without costly plane-change doglegs.

Spectrum stands 28 meters tall with a diameter of 2.0 meters, designed to loft payloads up to 1,000 kg into Low Earth Orbit (LEO) or 700–800 kg into Sun-Synchronous Orbit (SSO).

Aquila Engines & Clean Propellants

Spectrum is powered by in-house designed Aquila rocket engines burning liquid bio-propane and liquid oxygen (LOX). Propane delivers high volumetric energy density with clean combustion characteristics, substantially mitigating soot accumulation and environmental footprint compared to traditional kerosene (RP-1) cycles.

Stage 1 clusters 9 Aquila Sea-Level engines generating ~750 kN of liftoff thrust. Stage 2 employs 1 vacuum-optimized Aquila engine delivering ~95 kN with multiple in-space relight capability for precise circularization burns.

Atmospheric Ascent & Flight Mechanics

This flight simulator runs numerical integration incorporating:

• Gravity Turn Program: Initial vertical climb transitioning to a programmed pitch kick at ~1.2 km altitude, allowing gravity to gently tilt the velocity vector towards horizontal orbital insertion.
• Dynamic Pressure (Max-Q): Computed from atmospheric density $\rho(h) = \rho_0 e^{-h/H}$ and airspeed $q = \frac{1}{2}\rho v^2$, peaking near T+72s.
• Mass Depletion & Tsiolkovsky Equation: Continual rocket mass loss as 9 engines consume ~240 kg/s of propellant in Stage 1, driving acceleration up to 4.5g before MECO.