Free new parachute calculator!!!! We need feedback.

[Valkyrie Recovery Systems]

Attention Hobby Rocket Flyers!

Discover the heights you can reach and precisely plan your next launch with our Brand-New Descent and Drift Calculator! Designed specifically for the passionate rocket hobbyist, this tool aims to elevate your rocket flying experience by providing detailed estimations on descent rates, times, and drift distances.

Why Check Out Our Calculator?

• Tailored to Hobbyists: Whether you're launching small rockets in your backyard or heading out to larger fields, our calculator is built for all levels of hobby rocket enthusiasts.
• Enhance Your Launch Planning: Get accurate descent estimations to ensure your rocket's safe return to Earth. Perfect for testing different parachute configurations and understanding wind impact.
• User-Friendly Interface: We've made it super simple to enter your rocket's parameters and get instant calculations.

But we're not stopping there! We believe in continuous improvement and the power of community feedback. That's why we're inviting YOU to test drive our calculator and share your thoughts. Your insights could help shape the future of rocket hobby flying!

Try it out now: https://www.valkyrierecoverysystems.com/simple-chute-calculator-for-rocketry-under-construction.html

We Want to Hear From You! After you've given it a go, please let us know what you think. Did it enhance your planning process? How can we make it even better? Your feedback is invaluable to us.

Join the adventure and be part of the journey to perfect hobby rocket flying. Let's launch rockets smarter, not harder!

 

[ljwilley]

Cool! Will have to give it a try for my next rocket launch!

 

[mtnmanak]

Very nice tool - well done!

Love the simplicity of it.

Some ideas if you are iterating (none of these are show-stoppers, just nice to have):

- Would be nice to be able to choose the measurement units - metric vs. imperial, inches vs. feet, fps vs. mph
- May be a good idea to see if pre-populating some of the fields with common values would work. Drag co-efficient could probably pre-populate at 1.6, wind speed at 5 and landing altitude at 0, for example. This would make the process quicker for people who just want to use default values and not have to put those in every time. Also, it may help people that don't actually know what the drag coefficient is - at least some default would get them up and running.

 

[mtnmanak]

Another suggestion - have some info on the page about what recommended outcomes should be - what is a good descent velocity for a drogue? For a main? you could even incorporate that into the results with a comment in each line - something like "Great descent speed!" or "Warning: This descent speed may be considered too fast!"

And, well, it would seem like it would be good for business if, after the sim it gives the user some recommended parachutes to check out that would work for their rocket

 

[mtnmanak]

Maybe a toggle switch for single-deploy/dual-deploy? I think if I just make the drogue info "0" and make the apogee and deployment altitude the same, it would give me single-deploy results, but it is confusing right now. If toggling is not the desired solution, maybe two columns - single-deploy sim on one side, dual-deploy on the other? If nothing else, some comment on the page that explains how best to use the tool for a single-deploy scenario.

 

[Valkyrie Recovery Systems]

Maybe a toggle switch for single-deploy/dual-deploy? I think if I just make the drogue info "0" and make the apogee and deployment altitude the same, it would give me single-deploy results, but it is confusing right now. If toggling is not the desired solution, maybe two columns - single-deploy sim on one side, dual-deploy on the other? If nothing else, some comment on the page that explains how best to use the tool for a single-deploy scenario.

Those are all great suggestions! This is an initial version of what we are hoping to get to. It will never have the resolution or complexity of what we use for commercial contracts, but we are hoping to develop something that gives a good representation of potential fall speeds, times and wind drift. This will hopefully help everyone with drogue sizing, main's deployment height and potential recovery distance. It may take a little while to get to a point where the calculator is user-friendly while also providing all of the important information we are wanting to. Current resolution this calculator is working on is every 100ft in altitude and only 100 simulation runs. Our commercial system is currently at 1/100 sec and 100k-1mil simulation runs, which is a little too much for hobby use IMO.

 

[RocketDestroyer]

I notice that it is possible to set a negative numbers for all of the values. It would be nice to limit the numbers to positive values. Probably just me but I can't find on your site where you specify the coefficient of drag for you chutes?

 

[kjhambrick]

Nice !

Compares nicely to Blue Raven Data and my hand calcs for a flight from last Saturday !

Thanks !

-- kjh

 

[NTP2]

I agree on having a default CP because I don’t have a clue on how to get the CP for a parachute.

 

[Buckeye]

This would be the ultimate capability for me:

Use the Windy API to retrieve wind vector vs. altitude for a specific lat/long location and date/time. Then, create a kml file of the drift to plot in Google Earth.

Current resolution this calculator is working on is every 100ft in altitude and only 100 simulation runs. Our commercial system is currently at 1/100 sec and 100k-1mil simulation runs, which is a little too much for hobby use IMO.

Basic descent calculators simply use the terminal velocity equation. I assume you are updating air density at 100 ft intervals.

I don't know anything about commercial systems, so what are you solving exactly that requires 100 to 1 million simulation iterations? Are you solving some differential equations or adding stochastic variability?

 

[Valkyrie Recovery Systems]

I notice that it is possible to set a negative numbers for all of the values. It would be nice to limit the numbers to positive values. Probably just me but I can't find on your site where you specify the coefficient of drag for you chutes?

I have attached a 'master list' of vendor's drag coefficients. I believe everything is correct and complete on here, but let me know if you find something wrong.

 

[kjhambrick]

I have attached a 'master list' of vendor's drag coefficients. I believe everything is correct and complete on here, but let me know if you find something wrong.

Wow !

Thanks for that list !!

-- kjh

 

[RocketDestroyer]

I have attached a 'master list' of vendor's drag coefficients. I believe everything is correct and complete on here, but let me know if you find something wrong.

Thank you. This is great info.

 

[kjhambrick]

Here is some hard data from my flight last Saturday.

Pretty windy last Saturday: Austin Bergstrom 2024-03-02 (This history is as close as I could find for our Hutto Site).

On the Pad and in the tree with GPS coordinates for each:



The wind was 12 mph and I am not sure about winds aloft.

Density Altitude Apogee was 3612 ft

The distance between the pad and the tree is 1382 ft

The Valkyrie App says 1357 ft !



Pretty dang good for the wind speed SWAG on my part !

-- kjh

This is liftoff looking NNE. Wind was from the SSW. 'My' 10-ft rail is the one just to the left of the smoke column.

Note how far the smoke column has drifted !



EDIT: I need to subscribe to windy.com !

EDIT[2]: These are the launch site environmental conditions:

# Launch Site = AARG Hutto, TX site
# Launch Date = 2024-03-02
# Launch Time = 12:48:02.939
# Site Latitude = 30.614698 deg
# Site Longitude = -97.497814 deg
# Site Altitude = 640 ft
# Site Temperature = 75 F
# Site Pressure = 992.88 mb
# Site Pressure Alt = 561 ft
# Wind Speed = 12 mph ( estimated )
# Rail Length = 10 ft
# Relative Humidity = 47 %
# Speed of Sound = 1134 ft/sec # ./sos.sh 75 -> Mach( 75 F ) = 345.48 m/sec ( 1133.5 ft/sec, 773 mph )

This is the Blue Raven Altitude Data for the Flight:

Note that Inertial Altitude is meaningless after Apogee.

 

[TonyL]

I just tried the calculator and it does not work for me? It says "Please select a valid value. The two nearest valid values are 0 and 1.", and oddly the way it is implemented, it won't let me take a screen shot of it, as it does not seem to have focus and it evaporates as soon as something else does get focus. It does not highlight anything to show where the problem is, and the 'valid values' suggested don't make sense either.

I really like this calculator concept. The first thing that came to mind when I read the thread title was exactly this.

One suggestion is to not just auto-populate the wind entry boxes every 5kft. One could argue that above 60kft it really does not need that much altitude resolution. Maybe every 20k above 60k?
A 'populate defaults' button would be handy. One can debate forever what the defaults should be, but maybe a place for default wind and default direction would be handy?
one other thought on units: upper winds are typically reported MSL, it would be nice to be able to enter wind data directly rather than have to convert to AGL. That or a selector for MSL vs AGL.
br/
Tony

OK I have poked at it a little more and it does not seem to like decimal values? I used integers for rocket weight and drag coefficient and the error stopped appearing, however now when I click the button it does nothing? I tried it with a pretty simple data set and still does not seem to work. The page does not look like the screen shot in a previous post.

my screen shot issues may be more of a windows thing, this is what I see for a rocket weight of 0.8 lbs. If I change it to 1.0 lbs, the error goes away but there is no output.

 

[Valkyrie Recovery Systems]

I just tried the calculator and it does not work for me? It says "Please select a valid value. The two nearest valid values are 0 and 1.", and oddly the way it is implemented, it won't let me take a screen shot of it, as it does not seem to have focus and it evaporates as soon as something else does get focus. It does not highlight anything to show where the problem is, and the 'valid values' suggested don't make sense either.

I really like this calculator concept. The first thing that came to mind when I read the thread title was exactly this.

One suggestion is to not just auto-populate the wind entry boxes every 5kft. One could argue that above 60kft it really does not need that much altitude resolution. Maybe every 20k above 60k?
A 'populate defaults' button would be handy. One can debate forever what the defaults should be, but maybe a place for default wind and default direction would be handy?
one other thought on units: upper winds are typically reported MSL, it would be nice to be able to enter wind data directly rather than have to convert to AGL. That or a selector for MSL vs AGL.
br/
Tony

OK I have poked at it a little more and it does not seem to like decimal values? I used integers for rocket weight and drag coefficient and the error stopped appearing, however now when I click the button it does nothing? I tried it with a pretty simple data set and still does not seem to work. The page does not look like the screen shot in a previous post.

my screen shot issues may be more of a windows thing, this is what I see for a rocket weight of 0.8 lbs. If I change it to 1.0 lbs, the error goes away but there is no output.
View attachment 634331

We just returned it to the previous version. Now we are back working out the bugs on the one you just tried; and trying to figure out why it didn't work properly. Try again though with our 'previous' version. Thank you for alerting us though.

Ben
CEO
Valkyrie Recovery Systems

 

[Absouloot]

Great job Ben! I will echo a previous comment, I do like the simplicity. I will plan to take it out to our next launch and try it out!

So, for the next iteration, allow the user to drop a pin on something like Google Maps, and then with the calculations, pin point where the rocket will land!