Frequently Asked Questions (FAQ)

How Do I Simulate Multi-Stage Rockets?

RocFlight can handle an infinite number of stages, however the user must set the initial conditions appropriately for each stage. For the first stage enter your vehicle data such that it reflects the entire rocket. The diameter used here should be the diameter of the largest stage of the configuration, and the vehicle mass should be that of the entire vehicle minus the first stage motor. Do not forget to include the weights of the upper stage motors in the vehicle weight you enter for the first stage.

Run the simulation for the first stage and then go into the trajectory data file and determine the point at which you want to ignite the second stage. Record the value of the rocket's velocity, angle, altitude, and range at this point so that you can use these as your initial launch conditions when you go to simulate the second stage. If you wish to use the conditions at motor burnout for the start of your second stage, then these are conveniently provided on the Trajectory Summary data form. This process can be repeated as many times as is needed.

Why Isn't the Velocity Negative After Apogee?

The acceleration and velocity in RocFlight are defined with respect to a reference frame traveling on the nose cone of the rocket vehicle. After apogee the nose cone rotates towards the ground and velocity is considered positive in the direction the nose cone points. The acceleration indicated, is the acceleration that would be felt by an observer (pilot) traveling with the vehicle. Positive g's push the observer to the rear of the rocket and negative g's force the observer forward in the rocket.

Why is the Thrust Negative?

The only way for the thrust to be negative is if the user specifies a negative value in their thrust versus time curve, or if the user specifies a very low design exit pressure and/or a very large exit diameter. In this situation the pressure thrust term could be negative and have a magnitude larger then the momentum thrust, thus causing the total thrust to go negative.

How Do I Use Files I Created in wRASP?

You can use the Excel spreadsheet tools provided on the RocFlight website to convert your current wRASP rocket and motor files into the native RocFlight format. These spread sheets have embedded macros that convert the spreadsheet data into data files written to a user specified directory. Follow the directions under the File Support section at www.RocFlight.com.

What Do the Letters Stand for in the Rocket Names?

The leading letters in each rocket vehicle name stand for the manufacture of that rocket kit. Below is a list of each of these acronyms as reproduced from the wRASP vendor file.

U Unknown
NONE no manufacturer
AAA AAA Model Aviation Fuels
ACE ACE Aeronautics
AP Apogee ; P ; AP
APA Apogee/Aerotech
AT Aerotech ; A ; Aero ; AEROT ; AT-SU ; AT-RMS ; AT-EJ ; A-RMS ; A-J ; A-M ; A-WL ; AT-MWL
AIL Aerotech/ISP/LOC
APS Advanced Propulsion Systems
ASP Aerospace Specialty Products
AVI Aero Ventures Industries
BAH Boyce Aerospace Hobbies
BAM BAM Industries
BD Binder Design
BSR Black Sky Research
CEN Centuri Engineering, Inc.
COR Cosmodrome Rocketry
COX Cox Hobbies, Inc.
CR Cluster R
CT Cotriss Technology
CUS Custom Rocket Company
DB Dragon's Breath
DCD Dynacom Composite Dynamics, Inc.
DD Dangerous Dave's
EA Edmonds Aerospace
EGN Energon ; ENG
ES Estes Industries, Inc. ; E
FSI Flight Systems, Inc. ; F
HL Hobby Lab
HLP Hobby Labs Prototype
HT Hypertek ; H
IA Impulse Aerospace
ID Impulse Dynamics
ISP Industrial Solid Propulsion
JH Jim Hart
LOC LOC/Precision
LOCC LOC Custom Engineering
MB Microbrick
MSH Mountainside Hobbies & Manufacturing
MRC Model Rectifier Corporation
MRED MRED Industries, Inc.
NCR North Coast Rocketry
NRI Nordic Rocketry Incorporated
ORW Orion Rocket Works
PD Prodyne
PER Public Enemy Rockets
PH Pratt Hobbies
PI Propulsion Industries
PJ Plasmajet
PML Public Missiles Limited
QU Quest ; Q
RF Rocketflite
RM Rocketman
RNS Rockets n' Stuff
RRD Rocket R&D
SCR Scratch
SMI S.M.I.
SRW Seattle Rocket Works
SJ Synerjet
THOY Tiffany Hobbies of Ypsilanti
TLP The Launch Pad
TRM Kosdon Truly Recyclable Motors ; K ; KOS ; KTRM ; KOS-TRM
USR U.S. Rockets
V Vulcan Systems ; VU ; VUL ; V-TR2 ; Vulcan ; V-SS
VB Vaughn Brothers Rocketry
WR Wasatch Rocketry

Rocket Files Will Not Load?

The rocket files are probably not appearing because you have another application associated with the '.roc' file extension right now. RocFlight does not take over any previously associated file extensions when it is installed. To fix this problem you'll need to change the name associated with this file extension. To do this from Win 98 follow the directions below:

1. Go to start menu
2. Choose Settings....>Folder Options....>File types
3. Go to the file name that is associated with the .roc file extension (it may be SpaceCAD)
4. Click on the Edit Button
5. Delete whatever name appears in the 'Description of Type' entry field
6. Choose OK

This will should make the '.roc' extension appear as a general ROC file in the list of file types. The programs that previously used this file extension will still be able to use it, however now '.roc' files will not appear as files that can only be opened by that particular program.

Error Loading Database Files at Startup?

If an error occurs when attempting to either save or access files from one of the databases it is most likely because: (1) you have moved the RocketFiles, MotorFiles, CdFiles, or CaseFiles folders out of the working directory (where the executable resides) or (2) you have renamed one of the four previously mentioned folders. To fix this problem make sure these folders are present in the working directory and named exactly as shown above.

Error While Trying to Create New File from Database Editor?

If an error occurs when attempting to create a new file from the Database Editor it is probably because you have either deleted or overwritten the template file provided in each of the separate data folders. To obtain a new template file contact RocFlight Software Company at service@rocflight.com. You can also create your own template file simply by adding a file to the problematic data folder called 'template' which contains the format of the other files in the folder only without any data entered.

Burn Time Mismatch Error?

In order for the simulation to proceed the last thrust history time point must be equal to the burn time specified on the Motor Data input form. If this is not the case the program will terminate and prompt the user to resolve this issue. If using an imported motor when this occurs, simply access the problematic file using the Database Editor and correct the discrepancy.

(c) 2008 RocFlight Software Company