Seeking advice on starting-state wind conditions using OpenRocket and RockSim

[MetricRocketeer]

Hi TRF colleagues,

This summer I intend to fly my new LOC/Precision Warlock and possibly my old LOC/Precision Minie-Magg at Potter NY with URRG. I would like to enter reasonable starting-state wind conditions for simulating rocket launches using OpenRocket and RockSim.

For OpenRocket:

What do people recommend for these open-ended wind conditions: Average windspeed; Standard deviation; Turbulence intensity?

For RockSim:

For preselected categories pertaining to wind conditions, these are the choices. (Even though I have chosen default metric units, the categories are given in miles per hour.): Calm (0-2 mph); Light (3-7 mph); Slightly breezy (8-14 mph); Breezy (15-25 mph); Very windy (20-30 mph) — that overlap is not my error, but rather RockSim indicates those numbers; Strong (30-57 mph); Damaging (58 mph and higher)

For preselected categories pertaining to wind turbulence, these are the choices: Constant speed; Fairly constant speed (0.01); Some variability (0.04); Very turbulent (0.09)

Finally, in your opinion, I should say that wind starts at what altitude? Here I can put in my own value.

I thank everyone for their advice.

Stanley

 

[311stylie]

Starting state wind altitude would be based on your weather predictions. Windy makes a great app that predicts wind at ground level and then about every 500 - 1000 foot above that up to almost 6500 ft. You can use that data to dial in Rocksim including variability. Side note, I just started using Rocksim Pro and it allows you to build a wind table so I just plug that Windy data straight into it. It's pretty cool. I'm currently looking for a good resource for winds above 6500 ft..

 

[Art Upton]

FYI, Can't launch in winds grater then 20mph via safety code.

 

[Antares JS]

I usually do slightly breezy and some variability because those are pretty typical conditions for where I live.

 

[Buckeye]

95% of my sims are zero wind. Sometimes I will add constant 10-15 mph to get a feel for stability off the rail and weathercocking, if my design is marginal.

I turn off all the wind variability, as it merely randomizes the results. Randomizing just a couple sims doesn't make a lot of sense. You need 100's or 1000's of simulations for stochastic analysis. I guess you can manually do that by brute force with OR and RS, but there are better tools for Monte Carlo splash patterns and such, like RS Pro and rocketpy.

 

[MetricRocketeer]

I usually do slightly breezy and some variability because those are pretty typical conditions for where I live.

Thank you, @Antares JS. Very helpful.

 

[MetricRocketeer]

... Sometimes I will add constant 10-15 mph to get a feel for stability off the rail and weathercocking, if my design is marginal....

Thank you, @Buckeye. Very helpful.

 

[MetricRocketeer]

Starting state wind altitude would be based on your weather predictions. Windy makes a great app that predicts wind at ground level and then about every 500 - 1000 foot above that up to almost 6500 ft. You can use that data to dial in Rocksim including variability. Side note, I just started using Rocksim Pro and it allows you to build a wind table so I just plug that Windy data straight into it. It's pretty cool. I'm currently looking for a good resource for winds above 6500 ft..

Hi @311stylie,

Thank you for your response.

I know about Windy, and it is indeed a good app, as you say.

I just wanted to know about wind conditions that would be useful for more or less average situations. That way, I could set RockSim and OpenRocket for such conditions and be fairly confident that I have reasonable settings. That is the information that @Antares JS and @Buckeye gave me above.

What you said about RockSim Pro is interesting and provides food for thought. I don't know if I want to spend the money for that app, but I suppose that I should consider it.

Stanley

 

[Handeman]

I'm with @Buckeye, I do my sims with 0 winds. That gives the highest possible altitude. That number and launch day conditions will determine if I fly it and what motor to use. Wind direction doesn't mean anything to the sims, but it can be huge out at the field. You have to learn to fly the field and sims don't really help much with that.

 

[Titan II]

Zero wind on the sim and common sense at the field.

 

[lakeroadster]

I run 3 separate sims: 4 mph, 10 mph and 20 mph. Then export each as an Excel spreadsheet and compare the data. The "Angle Of Attack" just as the rocket exits the launch rod will guide you as to the maximum wind speed is for each rocket.

​

 

[dmaaero]

https://www.ventusky.com/?p=34.1;-80.3;5&l=wind-10m

I'm currently looking for a good resource for winds above 6500 ft..

 

[sr205347d]

Starting state wind altitude would be based on your weather predictions. Windy makes a great app that predicts wind at ground level and then about every 500 - 1000 foot above that up to almost 6500 ft.

Windy.com will show forecast wind all the way up to 45,000 feet. Select a location, then Sounding. Look at the SkewT.

 

[sr205347d]

I'm currently looking for a good resource for winds above 6500 ft..

Another source would be https://aviationweather.gov/gfa/#winds




Select Products, Wind/temp data.

 

[311stylie]

Windy.com will show forecast wind all the way up to 45,000 feet. Select a location, then Sounding. Look at the SkewT.View attachment 638546

SR, sorry I didn't clarify, I was talking about the android app, not the website. If you have a trick for the app I'm all ears
But to your point and the other suggestions above, for plugging in a table into RockSim Pro the websites work wonderfully. Good tips.

 

[sr205347d]

SR, sorry I didn't clarify, I was talking about the android app, not the website. If you have a trick for the app I'm all ears
But to your point and the other suggestions above, for plugging in a table into RockSim Pro the websites work wonderfully. Good tips.

My android phone gives me the same info.

 

[311stylie]

Awesome! I will check it out. I vaguely remember that the app does SkewT now, I think they added it last year sometime. I researched how to read them then never used it. Looks like it's time learn it again. Thanks SR!

 

[sr205347d]

Awesome! I will check it out. I vaguely remember that the app does SkewT now, I think they added it last year sometime. I researched how to read them then never used it. Looks like it's time learn it again. Thanks SR!

For the wind, just tap on the screen and drag to the desired altitude. It will give the wind. No need to know anything about SkewT.

You can select the date/time too.

 

[sr205347d]

From another thread: https://www.markschulze.net/winds/

 

[Voyager1]

If you wish to take OpenRocket to the next level, you could employ the Multilevel Wind add on. This allows you to enter in the wind direction and speed at the multiple altitudes which will (hopefully) help improve the accuracy of the sims. Not quite as graphically satisfying as RockSim Pro, but it is free!

https://github.com/rocketsam2016/MultiLevelWind/releases/tag/latest

This wind information can be sourced from apps like Windy or from the aviation forecasts available from your government meteorological sites.

 

[sr205347d]

From another thread: https://www.markschulze.net/winds/

Here is the thread: https://www.rocketryforum.com/threa...iction-based-on-winds-aloft-forecasts.185800/

 

[MarsLander]

The "Angle Of Attack" just as the rocket exits the launch rod will guide you as to the maximum wind speed is for each rocket.

How do you do that?

 

[lakeroadster]

How do you do that?

Open Rocket​

Flight Simulation​

Plot/export​

Export Data​

 

[MarsLander]

Open RocketFlight SimulationPlot/exportExport Data

Sorry, I got that ^^...I meant how do you use the data as a "guide you as to the maximum wind speed is for each rocket."

 

[lakeroadster]

Sorry, I got that ^^...I meant how do you use the data as a "guide you as to the maximum wind speed is for each rocket."

The rocket needs to recover quickly to a less than a 5 degree angle in a 4 mph wind.​

Pick a motor that produces this result.​

 

[MarsLander]

The rocket needs to recover quickly to a less than a 5 degree angle in a 4 mph wind.

Is this extensible?

 

[lakeroadster]

Is this extensible?

As related to... ?​

 

[MarsLander]

Wind speed…

 

[lakeroadster]

Wind speed…

Just change the speed in the simulation. 4 mph, 8 mph, 12 mph​

​

 

[MarsLander]

Just change the speed in the simulation. 4 mph, 8 mph, 12 mph

What’s the criteria for different speeds?