RASAero: General question

[MetricRocketeer]

Hi TRF colleagues,

I have a general question about RASAero, please.

I am reasonably proficient in using OpenRocket and RockSim. (I don't think that I am overstating my credentials.) I value these wonderful programs, and I could not function as a devoted sport rocketeer without them both. However, I have never used RASAero. I have RASAero II installedon my computer, but I have barely looked at it.

So my question is this. Is RASAero a crucial program for serious involvement with sport rocketry? I will even make my question less extreme. Is RASAero important for our hobby? Am I missing out on something by not using it? Does it contribute information that OpenRocket and RockSim do not?

Thank you.

Stanley

 

[G_T]

Personally I prefer RasAero for analyzing rocket behavior and for sims. I have a lot more experience though with the earlier version of RasAero. Plots such as CP vs mach number and CP vs yawing angle are useful to me. I don't know if the newer Rocksim, or OpenRocket, have that sort of data presented.

Besides, RasAero matched up to reality a lot better for me.

Gerald

 

[rocket_troy]

I pretty much mirror Gerald's comments.

No metric units though (which is painful), so you might not like it.

TP

 

[mikec]

RASAero is important for extreme (fast and/or high) flights, but massive overkill for most sport rocketry.

 

[H. Craig Miller]

RASAero is important for extreme (fast and/or high) flights, but massive overkill for most sport rocketry.

Hopefully, it won't be too long before OpenRocket can import and export RASAero II files.

 

[Buckeye]

So my question is this. Is RASAero a crucial program for serious involvement with sport rocketry? .... Is RASAero important for our hobby?

You ask questions in a very strange manner.

RASAero has more detailed and probably accurate drag and Cp models. If your rocket is flying fast, far, and for a long time, then RA is a good choice.

English units only (blech) with limited significant figures.

Most annoying to me is the need to enter the total mass of rocket (rocket + motor) in ready-to-fly condition. The software will not automatically add the mass of the motor when you prepare for simulation (but it will automatically adjust the CG when a motor is selected. Weird.) So, you have to manually look up motor masses from other sources. This makes what-if studies with different motors very tedious.

 

[Buckeye]

Hopefully, it won't be too long before OpenRocket can import and export RASAero II files.

Exporting make sense, since OR is a better design/CAD package. However, importing RA files into OR has limited value, since the secret sauce of RA is at simulation time.

 

[user 30299]

Exporting make sense, since OR is a better design/CAD package. However, importing RA files into OR has limited value, since the secret sauce of RA is at simulation time.

Totally agree . . .

RASAero is not for the impatient types. You definitely want to read the manual, and start with a simple rocket, before
sitting down to give the program a test run.

 

[Chuck Rogers]

Exporting make sense, since OR is a better design/CAD package. However, importing RA files into OR has limited value, since the secret sauce of RA is at simulation time.

Generally, that is what is done. The rocket is initially laid out in OpenRocket or Rocksim, and then entered into RASAero II for more accurate Drag Coefficient (CD) and Center of Pressure (CP) predictions, and more accurate Flight Simulations, in particular at Supersonic Mach numbers and at high altitudes. This became almost a standard procedure on the Tripoli Class 3 Committee for analysis of Class 3 rockets. This is very common for extreme rockets and College/University teams. For professional use Users typically go from CAD files to directly (manually) entering the data into RASAero II.


So what is really useful is exporting a RASAero II file.


Some caution though. RASAero II includes additional Fin Airfoils which are not included in OpenRocket or RockSim, and many of these Airfoils are important for Supersonic rockets. (Note that I haven't checked the most recent updated release of OpenRocket.) The actual rocket Fin Airfoil may have been approximated by another Airfoil in OpenRocket or RockSim. So after importing the file into RASAero II, the rocket Fin Airfoil data should be checked.

Below are the Fin Airfoils included in RASAero II:
Hexagonal
NACA
Double-Wedge
Biconvex
Hexagonal Blunt-Base
Single Wedge
Rounded
Square


Additionally, for the very accurate Rail Guide and Launch Shoe drag models in RASAero II, the Rail Guides and Launch Shoes inputs should be checked and/or re-entered into RASAero II.


And of the course in the other direction, there are complex geometries in OpenRocket and Rocksim which cannot be entered into RASAero II, and have to be approximated in RASAero II.


But typically that is what is done, lay out the rocket in OpenRocket or Rocksim, and then enter the rocket into RASAero II for more accuracy in the aerodynamic predictions and the flight simulations.


Thus I (and others) are looking forward to the export a RASAero II file feature in OpenRocket.



Charles E. (Chuck) Rogers
Rogers Aeroscience

 

[H. Craig Miller]

Some caution though. RASAero II includes additional Fin Airfoils which are not included in OpenRocket or RockSim, and many of these Airfoils are important for Supersonic rockets.

OpenRocket only has very basic airfoil computations. Always verify the actual rocket Fin Airfoil in RASAero II.

Additionally, for the very accurate Rail Guide and Launch Shoe drag models in RASAero II, the Rail Guides and Launch Shoes inputs should be checked and/or re-entered into RASAero II.

OpenRocket will be able to export launch lug and rail button data for use in RASAero II. But, OpenRocket does not support launch shoes at this time.

And of the course in the other direction, there are complex geometries in OpenRocket and Rocksim which cannot be entered into RASAero II, and have to be approximated in RASAero II.

OpenRocket will be able to recognize geometries that are not supported by RASAero II, and the user will be given a warning.

On the OpenRocket import of RASAero II files side, although it may not be regularly used, that feature is a necessary learning tool to determine how best to integrate data from the two programs, including surface smoothness, motor data, and even launch conditions, as well as program limitation issues such as how recovery devices are triggered.

Chuck's input has been very helpful in understanding how to accomplish this goal.

 

[Chuck Rogers]

On the OpenRocket import of RASAero II files side, although it may not be regularly used, that feature is a necessary learning tool to determine how best to integrate data from the two programs, including surface smoothness, motor data, and even launch conditions, as well as program limitation issues such as how recovery devices are triggered.

That is a really good point. It is probably really helpful in that regard.

Chuck's input has been very helpful in understanding how to accomplish this goal.

You are very welcome! I'm looking forward to the RASAero II import/export feature.


Charles E. (Chuck) Rogers
Rogers Aeroscience

 

[MetricRocketeer]

RASAero is important for extreme (fast and/or high) flights, but massive overkill for most sport rocketry.

Hi @mikec,

Thank you for your input. Also, just what do you mean by "massive overkill for most sport rocketry"?

But to answer my own question, I think you mean that RASAero is more than what you need unless you are aiming for extremely high or fast flights. Right?

Stanley

 

[Neutronium95]

Hi @mikec,

Thank you for your input. Also, just what do you mean by "massive overkill for most sport rocketry"?

But to answer my own question, I think you mean that RASAero is more than what you need unless you are aiming for extremely high or fast flights. Right?

Stanley

I personally only ever really use RASAero to simulate rockets that are likely to exceed Mach 2. Openrocket is more than good enough for flights slower than that.

 

[John Kemker]

That is a really good point. It is probably really helpful in that regard.



You are very welcome! I'm looking forward to the RASAero II import/export feature.


Charles E. (Chuck) Rogers
Rogers Aeroscience

Chuck, is there any chance that future versions of RASAero will use SI units in addition to Imperial/US units of measurements?

 

[Chuck Rogers]

Chuck, is there any chance that future versions of RASAero will use SI units in addition to Imperial/US units of measurements?

John:

We'll try to add it in the next minor update, but it may likely have to wait until the next major update.


Charles E. (Chuck) Rogers
Rogers Aeroscience

 

[John Kemker]

John:

We'll try to add it in the next minor update, but it may likely have to wait until the next major update.


Charles E. (Chuck) Rogers
Rogers Aeroscience

Thanks, Chuck!

I currently run RASAero under Linux using WINE.