6-Degree-Of-Freedom Simulation Software
For Rocket Professionals

Answering that question is one of the key things that the new RS-PRO software will help you determine. Without knowing this, you may not ever get permission from the FAA or Office of Space Transportation (OST) or Range Safety at Cape Canaveral approval to launch your rocket.

The figure below is a plot showing 300 potential impact points of a particular rocket. The distribution of the impact points illustrates not just a nominal impact point, but provides a level of confidence with respect to the likelihood of an impact in any given region. Such data is indispensable in pre-launch safety analysis and is also of use in determining possible locations for wayward rockets. This is one of the main reasons to use RS-PRO.

Above Image: This is a typical splash-pattern generated by
RS-PRO. It shows the likely location where the rocket will land. You can also plot in distance from the launch point, or latitude/longitude coordinates.

Constructing these "splash pattern" plots is not easy due to various uncertainties that can occur during the launch, or due to changing wind conditions.

What RS-PRO™ does is to inject 18 constantly shifting variables into the launch simulation, and then predicts how these will affect the landing location of the rocket. For example, any margin of error in any of these parameters will change the flight trajectory of your high altitude rocket and where it may land:

• Mass Of The Rocket
• Moment Of Inertia
• Product of Inertia
• Center Of Gravity Location
• Axial Force Coefficient
• Normal Force Coefficient
• Center of Pressure Location
• Fin Cant Angle
• Total Impulse Of The Motor
• Propellant Mass
• Thrust Axis
• Wind Direction
• Wind Velocity
• Launch Rail Azimuth Angle
• Launch Rail Elevation Angle
• Ignition Failure Likelihood
• CATO Of The Rocket Motor Likelihood
• Deployment Failure Likelihood
• Chute Failure Likelihood

RS-PRO takes all eighteen of these variables into account at the same time! Based on these uncertainties, it create a likely landing zone where the rocket will touch down.

Above image: The splash pattern is a result of randomness caused by the uncertainties that you input. There are 18 different variables that can be adjusted.

Above Image: In RS-PRO you'll set the initial starting state of the launch. Not only can you adjust the elevation and azimuth angles, but your rocket can have an initial velocity, or it can be drifting with the wind
(balloon launch).

Above Image: To increase the accuracy of the simulations, you'll be able to input your own values for Cd versus Mach numbers. If these values are unknown during the design phase, RS-PRO can also estimate them for you, so you can get preliminary simulation results.

Above image: You can click on each point in the splash pattern. This will bring up detailed information about that particular point. You'll be able to see what uncertainties caused the rocket to land in this location. This will help you to determine which uncertainties are most critical to the launch; and you'll be able to take precautions to minimize them from occurring.

Above image: RS-PRO will export a data file of the landing points in the splash pattern. This data file is in .KML format, which can be dropped onto the free GOOGLE Earth software™ This allows you to get an aerial photo of where your rocket is likely to land.

Sample file: Download now, and drop the file onto the Google Earth software. Launch site is located in central Colorado, USA.

Above image: There is an abundance of information that can be gleaned from the trajectory plot in Google-Earth. For example:

1. See the launch and the ideal landing point on an accurate aerial photograph.
   
   
2. Get accurate coordinates for the launch and the landing points.
   
   
3. Visualize the landing "zone," which is the area bounded by the uncertainty points. Check to make sure that the rocket will land in a safe area. You can click on each uncertainty point and get the errors that would cause the rocket to land in that spot.
   
   
4. See the ground track of the rocket. With it, you can make sure it won't travel over populated areas.
   
   
5. Check out the ascent trajectory. Get a perspective on how high your rocket is really going to fly.
   
   
6. View the descent path. This gives you an indication of the wind direction and speed.
   
   
7. The spacing of the vertically lines are 1 second apart. So you can get a quick idea of time-of-flight.
   
   
8. You can also rotate the scene, zoom in/out and tilt the camera angle so you can see the terrain around the flight zone.

For some people, their first impression of the 3D flight profile is that it is just eye-candy, and they wouldn't assign a high value to it. That is very shortsighted.

Big rockets that fly to high altitudes are very expensive. Rarely does one person have the money to cover this cost themselves. Do you? Your project will probably require outside sources of funding. The best and most valuable reason to have the 3D flight profile is that it can be used to make exciting presentation to others. Can you imagine how critical this could be in securing funding ($$$) for your project? Your sponsors will see how diligent you've been in planning the flight and that you've covered every possible contingency.

Equally important, you can use the graphics in your public relations campaign for your project. Newspapers eat this stuff up, as often they don't have a clue what the planned flight will look like.

Plus, you can use RS-PRO's powerful rocket graphics to make detailed illustrations of the rocket itself, showing how advertising logos could be placed on the model for maximum effect (see the picture below). Your financial sponsors will be more readily support the project because they'll be able to see how it benefits them!

RS-PRO can be a powerful tool for you to get the money you need for your project!

If I purchase RS-PRO, do I also need to buy RockSim?

No. RS-PRO can do everything RockSim can do plus a whole lot more. RS-PRO can even open up Rocksim design files.

Does RS-PRO replace RockSim v8?

RS-PRO will be separate from RockSim. RS-PRO picks up where RockSim leaves off. While it retains all of RockSim's design capabilities, its flight simulator is designed to handle rockets that fly at faster speeds (up to Mach 10), and those that fly higher (up to 632 km above sea level).

The second main difference is that RS-PRO predicts flight performance in 6-degrees of freedom, where RockSim is limited to 3-degrees of freedom. This allows it to better predict the flight trajectory of the rocket.

Finally, RS-PRO is designed to estimate the landing zone (called a splash pattern) where a rocket is most likely to land based on 18 launch uncertainties. The earth is modeled as a rotating oblate spheroid, which is a must on rockets on high sub-orbital flights. Like in real life, a rocket launched straight up will land a bit to the west due to the rotation of the earth underneath it.

RockSim is intended for basic rocket analysis. It has proven itself over and over by thousands of rocketeers that it is a great low-price program for designing rockets and getting a detailed performance analysis. RockSim is here to stay and will be continually upgraded with new design features.

What happened to the SPLASH software?

Apogee Components has discontinued the SPLASH program. While SPLASH was a great program, it did not have an interface to enter the design of the rocket vehicle and the motors they used. It was not always easy or convenient to enter this data. The new RS-PRO software takes the best part of SPLASH -- its 6-DOF simulator -- and combined it with RockSim's easy-to-use design interface and its motor definition program called "Engine Edit." The result is a one-stop program to design high performance rockets.

In merging the SPLASH software into RS-PRO, we discovered several major errors in the SPLASH algorithms. As such, SPLASH should no longer be used for any launch predictions. These errors were corrected in RS-PRO. If you compare the results from SPLASH and RS-PRO, they will be different because of these errors.

What are the limitations of RS-PRO?

"RS-PRO is new, and there is still some work to be done on the aero; all aero-predictions from the release of the beta-version are preliminary." User discretion is advised.

Here are the known issues as reported by the beta testers from the USAF 45th Test Wing based at Patrick Air Force Base in Florida:

(a) MIRRORED CP INCORRECT FOR CYLINDERS. For the range of AoA=90 to180 deg (the rocket going sideways to tail-first orientation), and in the condition of a cylinder (stripping all the fins off any rocket), RS-PRO uses "mirroring" of the CP (returns FORWARD to the nose at 180-deg), when actually, it should continue drifting AFT to the tail, as AoA approaches 180 deg.

(b) USER-DRIVEN LABELS for "STABLE" vs. "MARGINAL". When an unwary user manually adjusts the "Static Margin Reference" (to "user ref. dia, below", or "max frontal", or "nose cone base", on front tab), RS-PRO will report the word "Marginal", based only on this arbitrary ref. dia.. Example: If an unsafe rocket w/ 0.5-caliber stability is reported "Marginal" (unsafe), the user may inadvertently change the reference to the NOSE diameter (1"), vs. BOOSTER diameter (3"), tripling the reported Static Margin, and RS-PRO will drop the "marginal" warning (toggling the logic on the value of 1.5 calibers). The rocket will be unsafe (marginally stable), but RS-PRO will imply it as "stable" because the user changed the arbitrary ref. dia.. Solution: Use max-diameter of the rocket for the reference area.

(c) SOMEWHAT LOW C_a (Axial Drag Coefficient). The subsonic base drag for typical blunt-tail rockets (power-off) is about 0.18 (0.15 to 0.2), while RS-PRO seems to run M<1 base drag around 0.06, reducing total C_a by ~0.1 (~20%). The forebody subsonic drag also seems to run a little low and indifferent to nose shapes, producing 0.19 to 0.29 for both streamlined (0.2) and ugly fuse/warhead nose shapes I've documented around 0.4 to 0.45 or so. The net effect, preliminarily, seems to be about a 50% overestimation of trajectory range. Much of the low forebody C_a appears to be the drop in from Mach 0->1 (common in skin friction calculations, but not seen in windtunnels).

(d) FIN EFFECTS MAY BE SOMEWHAT HIGH (Debatable). Overestimating the fin CP contribution at low ("linear range") AoA's (0-10 or 20 deg), pulls the CP estimation too far back at low AoA (reporting ~5.5 calibers for a rocket I have wind-tunneled at ~4 calib). Note: All CP estimates RS-PRO agree at the "Barrowman" AoA (90 deg), so the debate is only in deviation from Barrowman at low AoA. The effect seems similar to DATCOM, which is also an ongoing debate for this phenomena.

(e) SCATTER PLOT ZOOM (This is a cosmetic issue). Still can't zoom into the "ellipse of craters in the dirt", after doing an uncertainty run, to report to the customer (FAA, DOD, etc.) the "Circular Error Probable (CEP)".

Can I get an educational discount?

One of our main target markets for this software is universities and students. As such, we will be pricing it at the absolutely lowest bargain-basement rate. We cannot discount it any further for individual students or teachers. You may want to check out our Rocketry Grant program that provides assistance to educational organizations and rocketry clubs.

Can you donate a copy to our research project?

Sorry. If we donated a copy to your project, we'd have to donate one to everyone just to be fair. You may want to check out our Rocketry Grant program that provides assistance to educational organizations and rocketry clubs.

Is there a trial version of RS-PRO?

At this time, we are not planning on releasing one. The purpose of a demo is to allow a potential buyer to test the program to see if it is usable for their purposes. We think that this can be evaluated by using the free RockSim trial version. You see, the basic design interface is identical to RockSim. And the upward trajectory of RockSim is pretty accurate. The other features unique to RS-PRO are shown on this page.

Where can I learn how to use RS-PRO?

On the CD-ROM that you'll receive when purchasing RS-PRO, you'll find a series of videos that will walk you through the steps to lean how to use RS-PRO. If you'd like to view these videos immediately in a lower quality, compressed format, please visit our RS-PRO tutorial page.

What are the system requirements for RS-PRO?

They are the same as for RockSim (click here for details).

Can I install RS-PRO on more than one computer?

No.

What do you mean by "Software Activation?"

You can install RS-PRO as soon as you get the CD-ROM. But to actually run the software, it must be turned-on by us through a process known as activation. We will not do this until payment is received, and USA citizenship is verified.

Are there any restrictions to using RS-PRO?

Yes. You must be a USA citizen, and also be living in the USA to purchase RS-PRO. Why? Because we don't yet have an export license from the US State Department. This is something we would like to do in the future, so please check back to this page often.

What level of detail are the landing dispersion/splash patterns?

RockSim pro simulation are based on the Box-Muller algorithm. This translates to 3 sigma distribution.