Vehicle and flight · version 2.0

Vehicle design and flight simulation

Lay out the rocket around the motor you solved, or enter its mass, diameter and drag coefficient. The app flies it off the rail, through apogee and recovery, in the wind you specify. Apogee, top speed, stability margin and landing distance are listed at the top of the Flight page.

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Windows 11 (64-bit) and Apple silicon Macs (macOS 14 or later), version 2.0.1. The Mac app is signed and notarized; the Windows installer is not code-signed.

Flight page with the headline flight numbers above the trajectory drawn to scale — Flight page for the J360 motor in a 4.58 lb vehicle: 6,388 ft apogee, 1,074 ft/s (Mach 0.97) top speed, 19.0 g peak acceleration, 102 ft/s off the rail, lowest stability margin 1.57 calibers (0.85 in wind).

What it computes

Stability: Centre of pressure by Barrowman's method, centre of gravity through the burn, and the stability margin in calibers, also at the angle of attack the wind gives.
Drag: Build-up through Mach number for nose, body, fins and base, or a table computed on the CFD tab.
Trajectory: Launch rail and guides, thrust from the solved motor or an imported motor file, wind with layers aloft, apogee, and dual-deployment recovery to the landing point.
Second stage: A booster and a sustainer, and the booster's descent.
Dispersion: The flight repeated with spreads on wind, thrust, drag, lift-off mass and rail angle; the landing points and the ellipse that holds 95 % of them.
Sensitivity: How the results move with each input.
Loads: Normal force, shear and bending moment along the body at the worst instant, the tube bending stress, the fin root loads, and a fin flutter check.
Design: Lay out a vehicle around the motor, size the fins for a stability margin, or size motor and vehicle together for an apogee.
Launch replay: The whole flight to scale, zooming from the trajectory into the vehicle and the motor as it burns.

What you enter

The vehicle. Nose, body sections and transitions, fins, masses and the motor's position; or only the mass without the motor, the body diameter and a drag coefficient.
The motor. The motor solved on the Define page, or an imported .eng or .rse motor file.
The launch. Rail length and angle, and the wind at the ground and in layers aloft.
Recovery. Dual deployment, with a parachute sized for a descent rate if you want one.

Flight page with the vehicle given as a mass, diameter and drag coefficient only — The vehicle as a mass, diameter and drag coefficient only: 7,013 ft apogee and Mach 1.00 top speed with the same motor. Without a layout there is no stability margin (n/a).

What you get

The top of the Flight page lists apogee, top speed and Mach number, peak acceleration, speed off the rail, lowest stability margin, landing distance and direction, descent rate and lift-off mass. Below them are the trajectory to scale, the results tables, the loads, and the dispersion.

Landing points of 100 dispersed flights with the 95 percent landing ellipse and the nominal ground track — Dispersion of 100 flights: landing points, the nominal ground track, and the ellipse that holds 95 % of the landings (grid 2,000 ft).

Files

.pdf: Flight report: the vehicle, the motor, the flight numbers, warnings, and the dispersion when it was run.
.dxf: Build drawings: fin and nose templates, the fin marking wrap, and centering rings.
.mp4: Launch video: the whole flight to scale with the camera fixed or moving (licensed plans).
.png: The page's charts and drawings.
Imports: Motor files (.eng, .rse) and projects (.rplproj).

Limits

Barrowman's method assumes a slender body at small angles of attack.
Build-up drag is an estimate; a drag table from the CFD tab or your own data replaces it.
Dispersion reflects only the spreads you enter.
The fin flutter check is a screening estimate.
Flight results are preliminary; compare them with your own flight data.

Trial and licenses

The 30-day trial runs the vehicle and flight, with a watermarked PDF report. Saving projects, DXF build drawings, the vehicle's CFD and videos need a license. Personal ($10/month or $99/year, noncommercial work) and Business ($29/month or $290/year, commercial work) both include the whole application: liquid engines, solid and hybrid motors, vehicle and flight, and all of the CFD, with no plan-tier mesh cap. See pricing.

Other sections

Liquid engines Solid motors Hybrid motors CFD