Ok, I have a set of questions.... the software shows a reading for battery voltage. Great, but at what voltage does it stop working, and at what voltage do you normally go ahead and replace it?
FlightSketch Products for 2020
- Thread starter gtg738w
- Start date
Help Support The Rocketry Forum:
Mine is down at the Post Office, I'll get it this afternoon! 
Heybobareebob!
Anyway, it occurred to me that, if you intend to attempt to use the 3-axis accelerometer data (not sure how the program does), you need to orient the device so that you know which direction is pointing which way! And then if you have the insane notion (as I do) of attempting some sort of trajectory analysis with it, you have to bear in mind that the accelerometer axes are aligned with the rocket, not the planet. I'll attempt to keep the device aligned with the body tube on two axes and hopefully get all kinds of lurvely data to fiddle with... But I like this kind of stuff, and I liked Russ's approach.
Heybobareebob!Anyway, it occurred to me that, if you intend to attempt to use the 3-axis accelerometer data (not sure how the program does), you need to orient the device so that you know which direction is pointing which way! And then if you have the insane notion (as I do) of attempting some sort of trajectory analysis with it, you have to bear in mind that the accelerometer axes are aligned with the rocket, not the planet. I'll attempt to keep the device aligned with the body tube on two axes and hopefully get all kinds of lurvely data to fiddle with... But I like this kind of stuff, and I liked Russ's approach.
Last edited:
Whatcha think about this setup? 200# Kevlar (either that or 400# - that's all I have on hand!) Big 'O locking swivel connected to nose cone. I will also protect my precious w a pouch! 
There is also a loop for the parachute attachment point - would the Mini ride better attached to this point instead?
I do have 4 - 1/16" holes just below the bottom of the nose cone on the smooth part of the sustainer. Trying to decide if I want to drill holes in my other rockets going to LDRS39a!
There is also a loop for the parachute attachment point - would the Mini ride better attached to this point instead?
I do have 4 - 1/16" holes just below the bottom of the nose cone on the smooth part of the sustainer. Trying to decide if I want to drill holes in my other rockets going to LDRS39a!
Scott_650
Well-Known Member
I’d suggest a wrap of paper wadding around the Mini - little pouch secured with a bit of tape worked for me until I a bought one the Dino Chutes pouches.Whatcha think about this setup? 200# Kevlar (either that or 400# - that's all I have on hand!) Big 'O locking swivel connected to nose cone. I will also protect my precious w a pouch!
There is also a loop for the parachute attachment point - would the Mini ride better attached to this point instead?
View attachment 470743
I do have 4 - 1/16" holes just below the bottom of the nose cone on the smooth part of the sustainer. Trying to decide if I want to drill holes in my other rockets going to LDRS39a!
Hmm, I'm going to have mine in an hour or so, and I ordered the pouch with it, but does it still fit in an 18mm tube with the pouch? Guess I'll let everyone know if someone else doesn't answer!
I thought I'd posted Russ' answer to this in one of the FlightSketch threads but didn't find it, so I'll put it here. I asked him about this in November of 2019 and this is what he wrote me in response:
Russ Parrish email said:
We were also talking about winter temperatures and what they do to that little coin cell, which is why the comment about the discharge curve.
I typically change the cell if the voltage displayed spends most of its time at 2.4V or so. As Russ noted, it varies on the display quite a bit as the unit is running depending on what its doing at the moment you look.
It probably won't. The fleece pouches my wife makes for them limits them to BT-50 or larger and the stuff DinoChutes uses for pouches is much stiffer. In BT-20 I just wrap a little wadding around one....but I don't think I've ever flown one outside a dedicated compartment in a BT-20-based model.
The sensor is sensitive to direct sunlight and pressure shock from the ejection. The pouch protects the altimeter from the sunlight but not the pressure shock. Now I'm wondering if a BT-20 with masking tape on the ends would protect from pressure shock or if it has to be a thin bulkhead? 
No pouch used: https://flightsketch.com/flights/1665/
No pouch used: https://flightsketch.com/flights/1665/
Interesting. You can certainly see the pressure spikes affecting the vertical velocity calculation, but I wonder why all the pressure spikes on descent? I'm sure a dedicated compartment is superior (and you could really deal with the orientation issue I mentioned above), but I don't get those pressure spikes on descent.The sensor is sensitive to direct sunlight and pressure shock from the ejection. The pouch protects the altimeter from the sunlight but not the pressure shock. Now I'm wondering if a BT-20 with masking tape on the ends would protect from pressure shock or if it has to be a thin bulkhead?
No pouch used: https://flightsketch.com/flights/1665/
Not all "pressure spikes" are from actual pressure changes (though most are). The sensor is sensitive to mechanical shock, which is why the data around ejection are usually quite messy especially in a pouch-hanging-from-the-nose-cone situation. The pressure sensor is also is somewhat sensitive to sunlight. In looking at the flight Ron linked to, on second thought I'm thinking mechanical shock is the cause for the spikes. If it was pouchless in a BT-50 tube (Super Nova is BT-50-based) it could rattle around a bit even on ascent. Then there was a huge shock at ejection, and some clattering around during descent as well.
But @rklapp was the Mini just loose inside the clear payload section of the Super Nova? If so you've just affirmed why I use the fleece pouches even in payload sections, especially clear ones.
During descent, unless things are nice and smooth and the payload section (or pouch) doesn't swing around under the 'chute, there will be minor, and sometimes not so minor, pressure fluctuations that are real. Look back at the plots I posted a few posts back. You can see the difference, throughout the flight, between one in a pouch but otherwise out in the breeze and one in a payload section, both falling under the same streamer. Under a 'chute, if the payload section spins around, you can often see very regular-looking ripples in the calculated altitude data.
Added: after trying to line up the altitude with the accelerometer data, I'm back to the theory that these spikes are sunlight-induced. The biggest spikes are shortly before ejection and there's no disturbance in the accelerometer data corresponding with the spikes during descent, so I now don't think it's mechanical shock....
But @rklapp was the Mini just loose inside the clear payload section of the Super Nova? If so you've just affirmed why I use the fleece pouches even in payload sections, especially clear ones.
During descent, unless things are nice and smooth and the payload section (or pouch) doesn't swing around under the 'chute, there will be minor, and sometimes not so minor, pressure fluctuations that are real. Look back at the plots I posted a few posts back. You can see the difference, throughout the flight, between one in a pouch but otherwise out in the breeze and one in a payload section, both falling under the same streamer. Under a 'chute, if the payload section spins around, you can often see very regular-looking ripples in the calculated altitude data.
Added: after trying to line up the altitude with the accelerometer data, I'm back to the theory that these spikes are sunlight-induced. The biggest spikes are shortly before ejection and there's no disturbance in the accelerometer data corresponding with the spikes during descent, so I now don't think it's mechanical shock....
Last edited:
Here's a wider view. You can see the time/thrust curves of the motors consistent with an Estes B6 followed by a C6 (and a big jolt at staging) in the acceleration data, as well as a bunch of hash around ejection that doesn't line up with the calculated altitude spikes....
- Joined
- Jan 7, 2019
- Messages
- 1,357
- Reaction score
- 1,023
Well...even if, in your opinion, the documentation shouldn't be necessary, that's not an excuse for you to ignore documentation provided and then tell people here that your preferred option is the only one available when that documentation accurately states otherwise, as you did. When I posted my reply, your post read "You have to turn the mini off with the app...." which is what I was reacting to. Now it says:
You may turn an FS Mini off with the app, but that is not the only way it can be done regardless of your opinion on how it should be done.
Last edited:
user 35280
Well-Known Member
- Joined
- Jun 19, 2021
- Messages
- 1,468
- Reaction score
- 869
FlightSketch is down to (14) of the FS Mini altimeters.
...and 42 Comps.
I actually lost one (the one in the pictures, actually) for a time yesterday, right on the table I was using at the flying field. I set it down while reaching for wadding to wrap it in and once I got the wadding I didn’t see it. I thought it had blown off the table in a gust so my wife and I searched around on the grass around the table to no avail. Fortunately, I’d already plugged in the cell, so the altimeter was on, and I soon found that by using the signal strength on the app display that it wasn’t on the ground, it was somewhere on the table top. But where?? In short, we finally found it, sandwiched in between the pages of my log book. I’d set it down in the book, and the wind had blown some pages over it. The signal strength display, fortunately, had led me to look at the notebook:
user 35280
Well-Known Member
- Joined
- Jun 19, 2021
- Messages
- 1,468
- Reaction score
- 869
Looking forward to the FlightSketch SST
So I'm confused. I can't buy CR1225 batteries from Amazon (overseas) but I can buy BR1225. I went to the local battery store and they have BR1225 but not CR1225. They said the difference is the CR1225 are 48 mAh and the BR1225 are 50 mAh. They said they're the same but the BR can take higher temperatures. Why can Amazon ship the BR and not the CR? Will a BR1225 work in the Mini?
user 35280
Well-Known Member
- Joined
- Jun 19, 2021
- Messages
- 1,468
- Reaction score
- 869
That's interesting because how was flightsketch able to ship you a mini with a CR1225 battery in it?
You know, that's interesting. I needed CR1225 batteries for my Swiss Army knife a couple years back and couldn't find them then, either. At least the BR's have 2 additional mAh's. I don't know why they wouldn't work if they are the same size, maybe different chemistry?
ETA: Good point, @TigerHawk. I hadn't thought of it from that aspect!
ETA: Good point, @TigerHawk. I hadn't thought of it from that aspect!
I could always try eBay. The sellers have no regard for ATF... I mean DOT rules for shipping materials.
zog139
Well-Known Member
- Joined
- Jan 18, 2009
- Messages
- 453
- Reaction score
- 36
user 35280
Well-Known Member
- Joined
- Jun 19, 2021
- Messages
- 1,468
- Reaction score
- 869
I'm hoping Russ (FlightSketch) responds about the BR1225 battery and you can use that. In the meantime I'd say check on eBay and other online vendors.
Jim,
So fare I've only flown Comps in dedicated compartments. I think further up in this thread is a suggestion of how I'd do it if I were flying it in with the recovery stuff.
Have I ever flown any flights with a second altimeter? Let's see, how do I want to answer this? The Comp is functionally the same as the Mini—it does the same things in the same ways. It's just made from smaller components (and has the little li-poly cell for power instead of the CR1225 coin cell). I have many tens of flights with a FlightSketch device on the same flight as one or more other altimeters. Whenever I get a new kind of altimeter to fly the first thing I do is put it in with one I know and trust and see how they compare. When I'm beta testing (as I have done for AltimeterThree for the FS Mini/Comp) I do this over and over and over.
In the case of the FS Mini and Comp, when Russ approached Dan Wolf for NAR contest approval, there were many more comparative flight tests I did (since it was easier for me to get out and do it than it was for Dan). When Dan identified an issue with an earlier version of the firmware I did a bunch of comparisons of that case with Adrel ALT-BMPs and PerfectFlite Pnuts along with the FS Mini.
Hopefully at NARAM you and the others who have Comps will help the folks at Returns with how to read the data and record it, since this is kind of like the Adrel case where you need to bring your own computer. That said, since they use BLE, anyone at Returns who has either the iOS or Android app can connect and download the data (as long as it's not already actively connected to another device). It will be interesting to see how that all works out in practice. But no need to pull it out to read it, which I really like.
Here's a recent example showing an FS Comp with a MicroPeak. The Checkmate is a little two-stage BT-20 based model from Estes. I have the top inch and a half turned into a dedicated payload section.
Here's another with an Adrel. Sterling Silver is also a two-stage BT-20-based model, and again I've turned the top couple of inches into a payload section as shown in my NARCON 2021 presentation and the NAR Member Guidebook. Here it was flown single stage.
(both models use streamer recovery, so the descent is quick and kind of bumpy.
There's lots more....
That IS confusing. A quick search yielded this: https://www.reference.com/world-view/equivalent-cr1225-battery-6c5a99e09724d509
This suggests you should grab a BR1225 from your local supplier and give it a try. But, looking closer I find...
In an Amazon review of Energizer BR1225s there's this:
I know the FS Mini has widely ranging current demands depending on what it's doing. That may make the BR1225 unsuitable. Here's a BR1225 data sheet: https://industrial.panasonic.com/cdbs/www-data/pdf2/AAA4000/AAA4000C206.pdf
Here's the data sheet for the Renata cell Russ uses (and that I buy as replacements on Amazon): https://www.renatabatteries.us/sites/default/files/2017-12/CR1225_data_sheet_v07.pdf
Note that the Renata cell can support over 30x the continuous discharge current.
Certainly you can get CR type coin cells in the more common sizes used in car key fobs and such (2025s, 2032s), so there must be a way to get them to Hawaii. But maybe Amazon won't do it. I know when I get CR1225s or CR1025s (FireFly, MicroPeak) from Amazon they come in a way oversized box with the lithium battery warning label on it.
Last edited:
I dunno about sending them to "Har-wy-ire" (my granddad was from West Virginia!), but I can get them delivered for free:
Wally World CR1225 - a buck a piece...
That's Insten, don't know how good they are. EverReady is $4.99 for 2.
BEC's data sheet seems to indicate that the BR's can't supply the current.
Wally World CR1225 - a buck a piece...
That's Insten, don't know how good they are. EverReady is $4.99 for 2.
BEC's data sheet seems to indicate that the BR's can't supply the current.
- Joined
- Jan 7, 2019
- Messages
- 1,357
- Reaction score
- 1,023
If they are the same physical size and the same voltage, they will be interchangeable. The are likely squeezing a bit more capacity in the form factor by making the barrier material between anode and cathode layers slightly thinner.
I dunno, Mike. The data sheet an review seem to indicate that the BR1225's are current-limited. All the voltage, not enough milliamps. Maybe we can start having battery threads alongside epoxy threads!
Similar threads
