OpenRocket... A few items for my wish list.

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K'Tesh

.....OpenRocket's ..... "Chuck Norris"
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First I'd like to say thanks to the guys who are making OR such a wonderful product! My builds wouldn't be quite so fun as they are w/o it's assistance in fin design and testing hypothesis on my upscale builds.

Next, I'd like to ask for the following features:

A way of putting in the number of sides on a fin (say a Hexigon, so 6, etc...). Then you indicate what the lengths are of the respective edges... say starting from the root edge, then working clockwise around the fin (label them with letters that can be changed to names). With that you should get a finite number of possible fin shapes, and you simply choose the one that is your match. This eliminates having to figure out what the coordinates are (which is a major source of frustration for me). In the case where really bizarre shapes appear, perhaps you could also have a distance to point number (say A/B corner to C/D corner) for additional clarification.

A tutorial on creating freeform fins would be helpful. [EDIT] I did one myself... You can find it here.

Alternate colors for the 3D background... A lot of my rockets are mostly white, they blend in with the background, so it's hard to get an idea of odd shapes (e.g. when different diameter tubes are butted up against one another).

Thanks Guys!
Jim
 
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Also, it would be nice if the arrow keys on the keyboard could increment the adjustment sliders like in RockSim. Oh, and get the physics of boattails figured out. Give me those two things and I don't think I'd ever use RockSim again.
 
TUbe fins as mentioned earlier. Free-form nose cones. Just as you free-form a fin. Ability to angle a MMT. Ability to create and store parts (fins, free-form NCs, specific length of tubes, etc.)
 
The trick with tube fins and pods is that somebody needs to have the resources to do a bunch of research and create force models for them.

I would like to see the ability to enter a scale factor for motor thrust. It would make it possible to handle canted motors.

And since it is, as I understand it, a 6-DOF simulator, I would like to be able to use it to actually can't the motors and see what happens when one of them doesn't light, or when you accidentally stuff the wrong motor in one tube...but I realize that is a niche request.


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I have a question I have been meaning to ask for some time now. I have been analyzing a rocket designed by a young member of our club and was looking at the angle of attack during the flight and noticed the AOA in OR always stays positive. I ran the same design in RockSim and see the AOA oscillates, as expected. I have checked several other models and get the same results, which doesn't seem correct. Am I missing something here?

AOA_Openrocket.jpg

AOA_RockSim.jpg
 
I have a question I have been meaning to ask for some time now. I have been analyzing a rocket designed by a young member of our club and was looking at the angle of attack during the flight and noticed the AOA in OR always stays positive. I ran the same design in RockSim and see the AOA oscillates, as expected. I have checked several other models and get the same results, which doesn't seem correct. Am I missing something here?

Being a full 6 degree of freedom simulation, there is not any one "positive" direction for angle of attack; thus it takes the magnitude.
 
OpenRocket actually does adjust the sliders with arrow keys. You need to click in the text box you want to change. Then the up and down arrow keys increment by 1 in whatever unit you're using. I find that using in/64 and mm are pretty useful units to use on smaller rockets, and inches and cm on larger rockets.

Boat tails work just fine. I suspect you're interested in having fins on the boat tails right?

Kevin

Also, it would be nice if the arrow keys on the keyboard could increment the adjustment sliders like in RockSim. Oh, and get the physics of boattails figured out. Give me those two things and I don't think I'd ever use RockSim again.
 
All of the above plus fins on transitions! My rockets are often all transitions.


Richard
 
To "fake" fins on transitions, I apply my OR fins to the smaller diameter tube, and use the "Position relative to" to adjust them into the right place.

OR doesn't seem to take the impossibility of two objects occupying the same space in mind, and allows it. That's how I managed to get it to accept fins for my Velociraptor downscale's boat tail, as you can see in this old image below...

10184319346_24ed2eb050_c.jpg


As an added bonus, if you print the fin templates, you get TTW fin tabs already factored in.
 
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My wish list item? Selecting from multiple pre-saved launch conditions as a flight configuration. It'd be nice to save profiles for, say, a 800mm 1/8th rod angled downrange, 1.5m rail, 3m rail... similarly, I imagine users may want one profile for their local field's elevation, and a different one for a planned high-power launch e.g. BALLS.

Another thing wish list would be Cd override. There are some designs that don't Barrowman-sim, but have had their approximate drag coefficient empirically discovered, and it'd be nice to plug those in to at least 1DoF simulation to get a sense for appropriate motors and delay times.

And yes, tube fin support would be great :)
 
OR doesn't seem to take the impossibility of two objects occupying the same space in mind, and allows it.

Thanks for that tidbit, I was spliting my transition in 2 with a .01 BT between for locating fins which was very tedious but that makes it much easier. Have you compared to see if it adversely affects the sim?


Richard
 
The trick with tube fins and pods is that somebody needs to have the resources to do a bunch of research and create force models for them.
In my experience, Rocksim really nails it with tube fins. With my MPR tube fin launches, the altimeter measured altitude has been amazingly close to predicted. After seeing an impressive looking HPR tube launch at the local field, I worked on an idea for an easy to build, durable, high drag, low altitude (i.e., an APCP burner for show) rocket designed for tube launch, I built and flew this sub-scale prototype. Rocksim predicted it was stable, which I didn't really believe, and predicted the ideal motor delay would be a C6-3 (draggy!). It was perfectly stable, super draggy, and the C6-3 was the perfect delay. BTW, note the span diameter, a perfect fit in a 4" mailing tube:

14244843461_7b98c64f2b_o.jpg
 
Regarding tube fins. My daughter's rocket "Nuclear Fallout" was designed on OR. In order to simulate 3 tube fins she simply created six fins with the tube profile. Prior to launch, SS/EA 6BBL 71 Cuda copied it in Rocksim. The flight simulations were so close the difference wasn't worth mentioning, and definitely not worth the cost.

https://www.rocketryforum.com/showt...FALLOUT&highlight=Introducing+Nuclear+Fallout
 
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Regarding tube fins. My daughter's rocket "Nuclear Fallout" was designed on OR. In order to simulate 3 tube fins she simply created six fins with the tube profile. Prior to launch, SS/EA 6BBL 71 Cuda copied it in Rocksim. The flight simulations were so close the difference wasn't worth mentioning, and definitely not worth the cost.

https://www.rocketryforum.com/showt...FALLOUT&highlight=Introducing+Nuclear+Fallout
Nice! I always like to compare results between Rocksim and Openrocket, but since I create tube fin rockets in Rocksim, Openrocken won't accept them. Could you make the .ork file available here so I can see what she did?

EDIT: BTW, I'm also an Austrian School of economics proponent.
 
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Latest wish... A way of running 'all' motors on a simulation.

Here's how I imagine it... You have a 24mm powered rocket, and you want to pick the best 95mm "E" or "F" motor. You select 24mm diameter, and/or 95mm length "E" motor, and the simulation runs all commercial motors in the database. After running the simulation, you can choose altitude (high or low), or speed at deployment, and it ranks them for you. Alter the angle or the wind, and run it again, and again it picks your best option.
 
Latest wish... A way of running 'all' motors on a simulation.

Here's how I imagine it... You have a 24mm powered rocket, and you want to pick the best 95mm "E" or "F" motor. You select 24mm diameter, and/or 95mm length "E" motor, and the simulation runs all commercial motors in the database. After running the simulation, you can choose altitude (high or low), or speed at deployment, and it ranks them for you. Alter the angle or the wind, and run it again, and again it picks your best option.
I second that great idea with an added suggestion to allow it to be limited by chosen manufacturer(s) to match reload casing types on hand or brand preference. With the very powerful PCs these days, why not let them do most of the work?
 
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Buy ROCKSIM guys ...

and you will have a lot of the features you want. Small price to pay considering how you spend on rocket motors.

Rocksim does have some shortcomings. It is not a full 6-DOF simulator (unless you pay for the $1000 'pro' version), for example. It don't believe it has an equivalent to OR's listeners which let you modify the simulation. And I find it less intuitive to use. The main advantage it has seems to be support for tube fins and pods.
 
From my perspective, I'd rather spend the hundred bucks on motors...
 
That didn't make any sense. At all.


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I'm reading that as an implication is that people who use OR are clowns and don't deserve to spend the difference in cost on rocket motors.
 
I'm fine with clown shoes as long as I get quality open-source, extensible, modifiable, and redistributable software.

Also, there is only one choice on Linux.
 
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