What altimeter / data logger do you recommend for kids?

[WillyB]

Folks, I’d love your advice on a good first altimeter / data logger to help my kids graph acceleration and altitude curves for their rocket flights. I'm looking for something that saves many datapoints per second, ideally with wireless data access.

I’ve read good things on the forum about the Jolly Logic AltimeterThree, but it’s not available. Similar with the FlightSketch Mini. The Eggtimer Ion looks promising but I want something ready-to-fly, not a kit.

Any suggestions?

Thanks!

-Will


P.S. here’s my full wish list of capabilities, but I realize this is probably asking for too much

• Logs lots of data, like acceleration and altitude captured many times a second
• Easy to get to the data; wireless data download would be great
• Doesn’t require special software (or if it does, it works on Chromebooks)
• Fits 25mm / 0.98” diameter or larger rockets
• Easy to use with a stock rocket (no special payload sections needed, etc)
• Ready to fly (I don’t have the skill or patience to assemble a kit)
• Forgiving (like it doesn’t start logging just because my kid jostled it, doesn’t break easily, etc)

 

[Spacedog49Krell]

The Featherweight Blue Raven meets most of your wish list. However, I do not look at it as a first time altimeter. It is a high speed flight computer at 500Hz.

If the Eggtimer Ion at 20-30 Hz speed meets your needs, there are people on the forum that can assemble the Eggtimer kits for you.

 

[BEC]

The list of things you can actually buy today for a price that you’d want kids using it is pretty much limited to the Eggtimer ION. However, it is barometric only. It has no accelerometer, so acceleration data are derived from the baro data. You get something but that’s not really the best way to do it. To get acceleration data from barometric only, you will have to calculate it yourself. Velocity is available through looking at how far the rocket goes between samples.

It will (just) fit in BT-50 with a small enough cell for power. Data are accessed with a web browser, so I presume a Chromebook will work (I’ve not tried this).

In looking at your requirement set, I do not think such a device currently exists to meet them all and never has. Both the FlightSketch devices and AltimeterThree require iOS or Android apps to use them so they will not work with a Chromebook. Only AltimeterThree is really set up to be flown “in with the laundry” rather than in a dedicated payload section with its plastic case. You can do it with others but improvisation and care are required.

There are a couple more small recording altimeters. Both are barometric only and not really designed to be flown outside of a dedicated compartment, though they are both tiny enough that you can do it. One requires a Windows computer to read/download the data. That is the Adrel ALT-BMP, otherwise known as the North Coast MaxAlt. But it’s tiny and easy to lose and you can buy three ION kits for the price of one of them. And there’s the Altus Metrum MicroPeak. Downloading data from it requires a Java app and a unique optically-based USB to serial interface device. I don’t know if it can run on a Chromebook or not.

There is another on the horizon in the Circuit Wizardry Starlight Mini, but that one is very much a work in progress from a software perspective and supply is sketchy. It also interfaces with a Java app. It’s being developed by a young fellow who just graduated from high school, so I don’t know what the near-term prospects for development and support are. It does have an accelerometer aboard as well as a barometric sensor, though.

Estes was for awhile, on their education web site, promoting a device called a Pocket Lab Voyager. But it’s big, expensive, and does nowhere near the claimed data rate. I don’t know about talking to it with a Chromebook. The iOS app was not great and using it via a Windows machine had a different set of problems when I tried it. I’ve not messed with it for some time….I need to get back to bugging those folks to see if they got some of the issues I had with it sorted.

If I were trying to do what you propose, at the moment, really the ION is the only viable choice in my opinion, even if you have to outsource assembly, though building them is not terribly hard for the most part. I’ve done three of them as well as some other Eggtimer kits. I’ve flown all the altimeters I’ve mentioned and have at least one of each in hand, so am speaking from experience in each case.

Oh, and welcome to the forum!

Edit: update to reflect that the Eggfinder ION does not provide calculated accelerations in the dataset that can be downloaded after a flight.

 

[Azamiryou]

Both the FlightSketch devices and AltimeterThree require iOS or Android apps to use them so they will not work with a Chromebook.

Chromebooks can run Android apps. Performance tends to be poor, but should be functional enough for reading data and making charts.

"Should" is carrying a lot of weight there, though — I haven't used those altimeters nor their apps, so I can't confirm for sure that it works.

 

[BEC]

Chromebooks can run Android apps. Performance tends to be poor, but should be functional enough for reading data and making charts.

"Should" is carrying a lot of weight there, though — I haven't used those altimeters nor their apps, so I can't confirm for sure that it works.

Well, the .apk for the Android version of the FlightSketch app is on their web site. Perhaps someone can try it. I'm not likely to go buy a Chromebook just to see. I don't know if the current AltimeterThree app is still on GooglePlay or not.

AltimeterThree is really the closest thing to meeting all the OP's requirement, except for that pesky "you can't get one" thing....

 

[BEC]

Woot has a $50 Chromebook right now. Hmmmmmmmm.

Also I looked at a recent ION data file. No accelerations calculated. That’s just as well from just barometric data but that is one more of the OP’s desires the ION does not fulfill.

Edit: I did order one of those $50 (plus tax and shipping) HP Chromebooks from Woot. Yet another platform to get familiar with, I guess. I will see how well it talks to the ION (should be just fine, since it’s WiFi and serves a web page) and try to install the Android app for either AltimeterThree or FlightSketch just to see what that’s like. I probably won’t use it much, as I’m not a fan of giving my life away to Google these days….

 

[WillyB]

The Featherweight Blue Raven meets most of your wish list. However, I do not look at it as a first time altimeter. It is a high speed flight computer at 500Hz.

If the Eggtimer Ion at 20-30 Hz speed meets your needs, there are people on the forum that can assemble the Eggtimer kits for you

Thanks Spacedog! I appreciate it! I hadn't read about the Blue Raven before so I checked it out. It's not inexpensive, but I suppose you get what you pay for.

Thanks also for pointing out the Eggtimer sampling rate. I'm probably fine with that. I'm just trying to get my kids to start to understand data and graphs, and figured that by exploring some data and graphs around something they're already interested in (Rockets!) would be a good way to do it.

Honestly the data just needs to be plausible (so they can engage with it), it doesn't actually have to be right (none of us will actually know).

Thank you!

 

[WillyB]

Well, the .apk for the Android version of the FlightSketch app is on their web site. Perhaps someone can try it. I'm not likely to go buy a Chromebook just to see. I don't know if the current AltimeterThree app is still on GooglePlay or not.

AltimeterThree is really the closest thing to meeting all the OP's requirement, except for that pesky "you can't get one" thing....

Thanks BEC for your long and thoughful answer here. Yeah, the AltimeterThree does sound like the right thing, there's just that "you can't get one" issue that you mentioned.

I do think the Ion is appealing, I'm just not thrilled about building it from a kit.

You've given me a lot of good input here and I really appreciate it!

 

[cerving]

FYI, if you don't want to build our products there are people that have a side hustle doing that for you. Email us at [email protected] if you want the list.

 

[Azamiryou]

I'm just trying to get my kids to start to understand data and graphs, and figured that by exploring some data and graphs around something they're already interested in (Rockets!) would be a good way to do it.

Does the data have to be from their own flight?

1) You can use Open Rocket to get tons of simulated data. (Bonus, you can use the graphs to understand the effects of various changes.)

2) I'm sure people here would share data from their flights. You could get some from nominal and not nominal flights, and the kids can try to understand what happened. Data could include a wide variety of flights ftom LPR to HPR and various altitudes.

 

[BEC]

Thanks BEC for your long and thoughful answer here. Yeah, the AltimeterThree does sound like the right thing, there's just that "you can't get one" issue that you mentioned.

I do think the Ion is appealing, I'm just not thrilled about building it from a kit.

You've given me a lot of good input here and I really appreciate it!

You’re welcome. Rocket altimeters, especially for LPR/MPR, are one of my “things” as you can probably tell. Feel free to ask detailed questions about any of these.

It also occurred to me just now that I should have also mentioned the PerfectFlite Pnut. It’s barometric only as well, and requires a Windows app (the Mac app is only 32 bit and so won’t run under any recent version of MacOS) to read/download/export the data. But it’s already built and mostly robust. It is much closer in size to the ION than the other units I went on about. It comes with a LiPoly cell for power (charges via USB) in contrast to the ION which basically leaves the powering of it (and charging the power source) as an exercise to the student — I mean user.

The Pnut is one of the choices that is used for American Rocketry Challenge teams, but is the only one of them that offers downloadable data that can be subsequently plotted.

Supply is spotty — you have to keep an eye on perfectflitedirect.com — but since it’s used for ARC, it is available from time to time. See rocketcontest.org to see what ARC is about.

 

[Tractionengines]

If you want to look at data... There are those of us who post flight logs to the Flightsketch website. You can look through the flights and download a CSV File to do your own analysis. Just be sure to get permission from the flyer before using the data in any sort of public way....

Here is the link to my data. (There's a "bad file" or 2, where I got trash data. Then a few testing files where I was using a vacuum to test...and getting others to help troubleshoot it.) Feel free to use any of my real flights in any way you and your kids want to...There's things they can look for. Failed parachute deployment, early or late ejection charge firing, dual deploy vs apogee deploy, etc.

https://flightsketch.com/flights/?user=Tractionengines

Have fun.

 

[BEC]

Likewise I have hundreds of flights up there dating back to when the first FS Minis were in beta test in March of 2019 all the way to a few flights at NARAM-65 and one at my club launch last Saturday: https://flightsketch.com/flights/?user=bcawley1 Note that the accelerometer wasn't added to the Mini for some time and the firmware updated to show its data came later (June of 2020), so the early flights are barometric data only.

 

[Art Upton]

You’re welcome. Rocket altimeters, especially for LPR/MPR, are one of my “things” as you can probably tell. Feel free to ask detailed questions about any of these.

It also occurred to me just now that I should have also mentioned the PerfectFlite Pnut. It’s barometric only as well, and requires a Windows app (the Mac app is only 32 bit and so won’t run under any recent version of MacOS) to read/download/export the data. But it’s already built and mostly robust. It is much closer in size to the ION than the other units I went on about. I comes with a LiPoly cell for power (charges via USB) in contrast to the ION which basically leaves the powering of it (and charging the power source) as an exercise to the student — I mean user.

The Pnut is one of the choices that is used for American Rocketry Challenge teams, but is the only one of them that offers downloadable data that can be subsequently plotted.

Supply is spotty — you have to keep an eye on perfectflitedirect.com — but since it’s used for ARC, it is available from time to time. See rocketcontest.org to see what ARC is about.

Pnuts are in stock FYI:

https://www.perfectflitedirect.com/pnut-altimeter/

 

[NTP2]

People can solder egg timers for you.

 

[Spacedog49Krell]

Pnuts are in stock FYI:

https://www.perfectflitedirect.com/pnut-altimeter/

The major competitions using the Pnut are finished for this year. Stock should be available for the next 2-3 months.

 

[WillyB]

Does the data have to be from their own flight?

1) You can use Open Rocket to get tons of simulated data. (Bonus, you can use the graphs to understand the effects of various changes.)

2) I'm sure people here would share data from their flights. You could get some from nominal and not nominal flights, and the kids can try to understand what happened. Data could include a wide variety of flights ftom LPR to HPR and various altitudes.

Thanks Azamiryou!

I suppose the data doesn't HAVE to be from their own flight, but I'm trying to get them engaged and interested in understanding graphs and data, and I think it will be a lot easier to get them engaged if it's data from their own flight. And also I'd like them to explore how the flight data changes with a more powerful engine, etc. So I do want it to be from their own flight. And I want to get them more engaged with electronics too.

That said, I just took a look at OpenRocket and it looks fantastic! Thank you for the tip!

I love your idea of sharing data from various flights. That's really interesting. Especially the combination of normal and abnormal flights. I saw the post from Tractionengines below where he shared some flight data (https://flightsketch.com/flights/?user=Tractionengines). Are there other places you know of where people share data like that?

Thanks!

 

[WillyB]

If you want to look at data... There are those of us who post flight logs to the Flightsketch website. You can look through the flights and download a CSV File to do your own analysis. Just be sure to get permission from the flyer before using the data in any sort of public way....

Here is the link to my data. (There's a "bad file" or 2, where I got trash data. Then a few testing files where I was using a vacuum to test...and getting others to help troubleshoot it.) Feel free to use any of my real flights in any way you and your kids want to...There's things they can look for. Failed parachute deployment, early or late ejection charge firing, dual deploy vs apogee deploy, etc.

https://flightsketch.com/flights/?user=Tractionengines

Have fun.

Oh, super cool. I looked through a few of these. Thank you for sharing!

 

[Spacedog49Krell]

Attached are two flights of my MiniMean, half a Mean Machine, on an E12-6 and a G40-10. The flight computer records 10 channels at 250Hz. Lots of interesting gyro and accelerometer data that you won't see with a barometric only sensor at 20-50Hz. During the first 300ms you can see what happens as the rocket slides up the launch rod, then as it transitions from the launch rod to free flight. The 250Hz data rate is easier to manipulate over a 500Hz to 1000Hz data rate system.

 

[WillyB]

Attached are two flights of my MiniMean, half a Mean Machine, on an E12-6 and a G40-10. The flight computer records 10 channels at 250Hz. Lots of interesting gyro and accelerometer data that you won't see with a barometric only sensor at 20-50Hz. During the first 300ms you can see what happens as the rocket slides up the launch rod, then as it transitions from the launch rod to free flight. The 250Hz data rate is easier to manipulate over a 500Hz to 1000Hz data rate system.

Thanks Spacedog!

Is that from the Featherweight Blue Raven?

 

[Spacedog49Krell]

Thanks Spacedog!

Is that from the Featherweight Blue Raven?

No, it's from an early InSight 200+ from Russia. I was their Technical/Sales person in the US until the fighting in Ukraine started.

 

[BEC]

Well, UPS just dropped off the box with the HP Chromebook from Woot. I guess I'll be looking into Android apps on there, as well as confirming that it talks to the Eggtimer ION over WiFi. But I have a couple of other data-related things to do first (sharing some data from one flight of a Starlight Mini with the developer) and we're still in the middle of putting things away after Sod Blaster VI. So ping me in two or three days to see what I've figured out.

 

[BEC]

Am typing this on the Chromebook. I installed the AltimeterThree Android app, but it crashes on startup...so I haven't managed to see if it will actually work. Will now try communicating with an ION and pop back here to report if it works. Of course I'll have to get off here first since the ION uses its own WiFi "network" to commuicate.

Added (and being typed from my iPad): it took a little fussing, but it worked. One can communicate with an ION with a Chromebook. Of course the Chromebook needs to have something installed that will open a .csv file once you download the data…and getting it from the downloads folder to Google Sheets was not intuitive…at least for this non-Google user.

I have also learned that Chromebooks are Linux boxes behind the scenes and more recent ones give you a way into there. One of the things THAT opens up is the ability to sideload Android apps from .apk files, so I could at least try to run the FlightSketch app on it. I should also be able to (if there’s room, this cheap Chromebook doesn’t have a bunch of storage) load LibreOffice, which will give me non-Google tools to deal with, among other things, .csv files.

The Android version of Firefox, on this Chromebook, is s l o o o w w .

 

[NTP2]

Am typing this on the Chromebook. I installed the AltimeterThree Android app, but it crashes on startup...so I haven't managed to see if it will actually work. Will now try communicating with an ION and pop back here to report if it works. Of course I'll have to get off here first since the ION uses its own WiFi "network" to commuicate.

Added (and being typed from my iPad): it took a little fussing, but it worked. One can communicate with an ION with a Chromebook. Of course the Chromebook needs to have something installed that will open a .csv file once you download the data…and getting it from the downloads folder to Google Sheets was not intuitive…at least for this non-Google user.

I have also learned that Chromebooks are Linux boxes behind the scenes and more recent ones give you a way into there. One of the things THAT opens up is the ability to sideload Android apps from .apk files, so I could at least try to run the FlightSketch app on it. I should also be able to (if there’s room, this cheap Chromebook doesn’t have a bunch of storage) load LibreOffice, which will give me non-Google tools to deal with, among other things, .csv files.

The Android version of Firefox, no this Chromebook, is s l o o o w w .

I use one for school, they work well for the intended use of using google cloud products as they have a good internet connection, I can even use onshape on them, but they make the price work with bad onboard performance.

 

[BEC]

Firefox on Linux on the Chromebook is tolerable (am typing on that now while watching the repressurization of the Dragon after the commercial EVA by Jared and Sarah) on my iPad. Much better than running the Android version here on the Chromebook.

I tried to install OpenRocket in Linux but once I found where the downloaded file actually was when I ran the installer it failed. I'll move that discussion over to one of the OpenRocket threads. I'm not sure how much trouble it will be worth to try to make that work on this machine.

 

[NTP2]

Firefox on Linux on the Chromebook is tolerable (am typing on that now while watching the repressurization of the Dragon after the commercial EVA by Jared and Sarah). Much better than running the Android version.

I tried to install OpenRocket in Linux but once I found where the downloaded file actually was when I ran the installer it failed. I'll move that discussion over to one of the OpenRocket threads. I'm not sure how much trouble it will be worth to try to make that work on this machine.

I’d suggest Crome, if you can tolerate it (I don’t care personally but I know some have strong opinions)

 

[BEC]

I’d suggest Crome, if you can tolerate it (I don’t care personally but I know some have strong opinions)

Of course Chrome is there by default. I'm just not a fan of being Google's product, hence the Firefox installation which I am running as I type this, while the SpaceX broadcast is running on my 13 inch iPad Air.

 

[NTP2]

Of course Chrome is there by default. I'm just not a fan of being Google's product,

Ok just know that it runs better with Chrome you can always change later if you need it (this place is not a good test but if it’s the most intensive thing then you will be fine)

 

[BEC]

Yeah, probably. On this machine, I don't know what I'm going to do with it really. . I did install the Android app for iLaunch, so I will try that when that device is released. I have a little Lenovo Thinkpad with Windows 10 on it that I use as my take-it-to-the-field computer for reading Adrels and the Starlight Mini I have. It also has OR on it and I can do field sims there.

Well, the Polaris Dawn EVA phase is over. I think I'm going to try to go to bed for awhile. It's just after 5 AM here.

 

[Art Upton]

Ok just know that it runs better with Chrome you can always change later if you need it (this place is not a good test but if it’s the most intensive thing then you will be fine)

Chrome can go direct to the hardware I bet , since it's the maker's browser. Firefox would have to use software calls.
Think back to early MS dos PC days, of word processors that had to use MS-DOS calls vs ones that went direct to the keyboard and screen hardware.*

* I leaned from Peter Norton how to write Assembler compiled machine code sub-routines to get fast performance in higher level code I was writing. Peter used to publish the "PC Tech Journal" and yes I had to read every one of them.