Micro IMU/Accelerometer datalogger like the FS Mini available anywhere?

[Seatechnerd83]

I have a MD 38mm rocket I've designed to go as fast and as high as humanly possible while still being robust enough to survive hopefully 10s of flights. It's maiden flight was at LDRS 41 on an I175 DMS motor to mach .95 and 6k feet and it landed directly in the MIDDLE of a corn field half a mile away so I'm quite confident in it for future flights. I currently only fly it with a 2s stick lipo and an eggfinder mini in it's payload bay. (Rocket design is a 24in 38mm wildman tube, with the WM 38mm FG nosecone. Payload bay is a 5in coupler section with end caps that is pushed into the booster section above a perforated aeropack retainer, with a hole directly in the middle to allow the 1/4in kevlar shock cord to pass through it to the streamer.) The rocket is designed to hold I500 sized motors. (although only Loki research motors actually ship with delays long enough to use the big motors and I dont have any hardware for LR motors and sadly dont plan on getting any anytime soon.)

Anyways, TLDR I need a tiny flight datalogger for my rocket and the FS mini is out of stock and is pretty much unobtanium for me. Preferably It has it's own battery, or It has the ability to take 7.4v from my 2s lipo already on board. (rocket's name is Lawn Dart 2.0 btw.)

 

[SolarYellow]

I think you can hook up an OpenLog data logging module (logs GPS data to micro SD card) to the Mini and it will log the GPS output. It's similar size and weight to a FS Mini.

 

[Adrian A]

I have a MD 38mm rocket I've designed to go as fast and as high as humanly possible while still being robust enough to survive hopefully 10s of flights. It's maiden flight was at LDRS 41 on an I175 DMS motor to mach .95 and 6k feet and it landed directly in the MIDDLE of a corn field half a mile away so I'm quite confident in it for future flights. I currently only fly it with a 2s stick lipo and an eggfinder mini in it's payload bay. (Rocket design is a 24in 38mm wildman tube, with the WM 38mm FG nosecone. Payload bay is a 5in coupler section with end caps that is pushed into the booster section above a perforated aeropack retainer, with a hole directly in the middle to allow the 1/4in kevlar shock cord to pass through it to the streamer.) The rocket is designed to hold I500 sized motors. (although only Loki research motors actually ship with delays long enough to use the big motors and I dont have any hardware for LR motors and sadly dont plan on getting any anytime soon.)

Anyways, TLDR I need a tiny flight datalogger for my rocket and the FS mini is out of stock and is pretty much unobtanium for me. Preferably It has it's own battery, or It has the ability to take 7.4v from my 2s lipo already on board. (rocket's name is Lawn Dart 2.0 btw.)

The Blue Raven is excellent at data logging, small, and will accept your battery. And it will handle dual deployment and more once you expand into that.

 

[Art Upton]

I think you can hook up an OpenLog data logging module (logs GPS data to micro SD card) to the Mini and it will log the GPS output. It's similar size and weight to a FS Mini.

Egg Timer says the Mini can't support the Open Log as their is no room for it on the board.
Quote " It is functionally identical to the Eggfinder TX transmitter, except that there’s no place to add an OpenLog datalogger (just no room…)"

Perhaps however there is a way to hack it into the data stream from off the board via the GPS pins on the rear I bet. The pins in the rear of the mini have the GPS data on them before they go to the Hope RF TX board.

(based on what I just read today in preparation for building before I get mine that I ordered; they have you test by tapping Serial data off those pins to make sure the GPS is working before you add the Hope RF board)

 

[Art Upton]

Ok, this will log the Velocity and other details, $20 for the kit, not that hard to put together:

https://eggtimerrocketry.com/home/altimeters-av-bay/
Go down to : Eggtimer ION WiFi-Enabled Flight Logging Altimeter Kit $20

 

[SolarYellow]

Egg Timer says the Mini can't support the Open Log as their is no room for it on the board.
Quote " It is functionally identical to the Eggfinder TX transmitter, except that there’s no place to add an OpenLog datalogger (just no room…)"

Perhaps however there is a way to hack it into the data stream from off the board via the GPS pins on the rear I bet. The pins in the rear of the mini have the GPS data on them before they go to the Hope RF TX board.

(based on what I just read today in preparation for building before I get mine that I ordered; they have you test by tapping Serial data off those pins to make sure the GPS is working before you add the Hope RF board)

https://eggtimerrocketry.com/wp-content/uploads/2021/07/OpenLog-and-Eggfinder-Users-Manual.pdf

 

[Art Upton]

https://eggtimerrocketry.com/wp-content/uploads/2021/07/OpenLog-and-Eggfinder-Users-Manual.pdf

That is not showing the MINI TX, but the standard TX in those instructions , the OP has a Mini. Also it will not give velocity data like the ION will, you can still connect it to the Mini's pins with it "off board' mounted elseware.

 

[SolarYellow]

That was the point. The instructions mention using the Mini, and I'm sure the "three wire" hookup instructions are applicable. It just has to be mounted separately, which is not a big deal. The FS Mini is about the same size and weight as an OpenLog. Maybe heavier, with the battery.

 

[BEC]

If the OP doesn't need any data that would come from an accelerometer (flight event timing, measured rather than calculated accelerations) then an Eggtimer ION could work, as Art suggests.

It has some quirks (which I've gone into elsewhere here on TRF I think) but for getting some performance data on something like is described in the first post, it could do the job. But since the thread title asks for an IMU, I think he's looking for accelerometer-based data, too.

And yes, I know an accelerometer is an IMU, but since a substitute for an FS Mini is sought, hopefully the OP does, too....

When I saw this thread, I pinged Russ Parrish at FlightSketch. He has hardware on hand for more Minis (and Comps) but something is preventing him from testing them, loading firmware and getting them otherwise made available, and I'm not clear on what that might be.

I also pinged John Beans about when/if we'll see more AltimeterThree, as it would surely do what the OP asks for, too. Last I heard (and it was quite some time ago) he, too, had hardware in hand but there was some kind of software/firmware hangup (if I remember correctly).

Sadly, so far, neither Russ nor John has replied.

If events and some flight statistics (apogee, altitude at ejection as well as times for boost, coast, apogee to ejection, overall flight time) are helpful but no graphing of flight data are OK, then AltimeterTwo could be an option. These ARE available.

 

[Seatechnerd83]

The Blue Raven is excellent at data logging, small, and will accept your battery. And it will handle dual deployment and more once you expend into that.

I haven't really considered blue raven yet due to cost. But since it's kinda just the best, especially if I want to convert this rocket to non-motor eject, I'll probably have to save up my rocket budget for a blue raven.

 

[SolarYellow]

I definitely plan to get on the Blue Raven bus eventually, probably even two of them, but only for mach-busters or air starts. The price takes me out of that market if I don't need those capabilities.

 

[cerving]

That was the point. The instructions mention using the Mini, and I'm sure the "three wire" hookup instructions are applicable. It just has to be mounted separately, which is not a big deal. The FS Mini is about the same size and weight as an OpenLog. Maybe heavier, with the battery.

If you just want to log the GPS data, yes, you can do a 3-wire hookup to the Mini's header to an OpenLog (3V3, GND, TXT-->RXD). You wan't get velocity and acceleration out of it, and the GPS' ASL altitude will most likely be lagging way behind your flight until sometime on the way down.

If you just want to log data and aren't doing any deployments and aren't going to use GPS, the ION will be fine. If you want GPS, deployments, altimeter logging, and GPS logging, you can get an Eggtimer Quasar and an OpenLog module... and they're on sale right now.

 

[Seatechnerd83]

If you just want to log the GPS data, yes, you can do a 3-wire hookup to the Mini's header to an OpenLog (3V3, GND, TXT-->RXD). You wan't get velocity and acceleration out of it, and the GPS' ASL altitude will most likely be lagging way behind your flight until sometime on the way down.

If you just want to log data and aren't doing any deployments and aren't going to use GPS, the ION will be fine. If you want GPS, deployments, altimeter logging, and GPS logging, you can get an Eggtimer Quasar and an OpenLog module... and they're on sale right now.

My main goal is to get a payload that logs acceleration, as I already have barometric altimeters that I can fit into the payload section.

 

[BEC]

@John Beans has not gotten back to me about the future of AltimeterThree. AltimeterTwo will give you peak and average acceleration, but not any data you can plot.

@gtg738w has also not yet replied. I know that more FS Minis exist that will some day be available.

Both of them seem to have other things on their mind. I just hope (as I have mentioned to them each privately) that it's a good busy for them and their families, even if it means we have to wait....

 

[kjhambrick]

If you just want to log the GPS data, yes, you can do a 3-wire hookup to the Mini's header to an OpenLog (3V3, GND, TXT-->RXD). You wan't get velocity and acceleration out of it, and the GPS' ASL altitude will most likely be lagging way behind your flight until sometime on the way down.

If you just want to log data and aren't doing any deployments and aren't going to use GPS, the ION will be fine. If you want GPS, deployments, altimeter logging, and GPS logging, you can get an Eggtimer Quasar and an OpenLog module... and they're on sale right now.

Cris --

Very interesting !

What is the OpenLog module called on your website ?

Thanks !

-- kjh

 

[cerving]

It's called "OpenLog"... look in the Purchase page under Eggfinder GPS Tracking System. We sell them for $12.

 

[cerving]

My main goal is to get a payload that logs acceleration, as I already have barometric altimeters that I can fit into the payload section.

You could do that with a Proton, and have six deployment outputs too. Its accelerometer is good for up to 200G's... I'm guessing that you're not going anywhere near that. It WILL fit in a 38mm coupler (I've done it), but not in anything much smaller than that.

For a project like that, I would be more included to make sure I had a GPS tracker in it... you can derive the average acceleration during boost pretty easily from flight data, but you ain't gonna have any flight data if you lose the rocket.

 

[kjhambrick]

It's called "OpenLog"... look in the Purchase page under Eggfinder GPS Tracking System. We sell them for $12.

Dang Cris ... I am not finding it ...

There are two instances of the word OpenLog but no description of the module.

Dooh !

I found it where you said -- under the Purchase Page !

Sorry and Thanks

-- kjh