Small cheap reliable altimeter

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AtomicStorm

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I have been building basic rockets for a while now and would like to start learning more about altimeters and onboard electronics. I would rather do the research and build my own electronics (and everything else in the hobby) for less money then just buying them completed. Working on a camanchee 3 kit now, so it has to be less than 25mm(.98"in.) in width. I looked at the estes altimeter and i think its too big, plus im sure i could find something smaller and cheaper. Any ideas?
 
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rharshberger

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The Estes altimeter is pretty unreliable but iirc it does fit a BT50 tube (Comanche 3 is BT50). I would look into the Perfect flight Firefly for altitude only or even better the Flightsketch Mini as it does logging and acceleration data . The FS Mini and Firefly are both priced near the Estes Altimeter in price but are magnitudes more reliable. Cheapers is harder to find but the Eggtimer Quark does altitude with dual deployment but no logging of data, the Eggtime also requires soldering as all Eggtimer products are kits, for apogee only deployment Eggtimer offers the Eggtimer Apogee.
 

boatgeek

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If you want to log data, an Eggtimer Quantum (requires assembly) or a Perfectflite Pnut are also good choices. The Quantum will also do dual deploy and air starts.
 

AtomicStorm

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This hobby is starting to add up quick. If i spend $20 on a airframe, idc if i lose it. But once i add $30 in alt., then i need to insure it with another $100 in gps. There has to be a more cost effective way. 🤔
 

AtomicStorm

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Actually come to think of it i have some spectrum receivers from my airplane stuff and i believe i have a telemetry module that plugs in rx and will read out everything.

Features
  • Single sensor provides all of the following information:
    • Location
    • Ground Speed
    • Altitude (Above Mean Sea Level)
    • Distance from Home
  • Works in both Surface and Air applications
  • Offers "plug and play" simplicity with TM1000 and TM1500 telemetry modules, and with all telemetry-integrated receivers that have an X-Bus connector interface
  • Easy to set up and use - no calibration needed
  • Water- and dust-proof case design accommodates any environment and weather conditions
  • Great tool for tuning models to achieve the highest speeds
 
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AtomicStorm

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Just need to find a battery small enough to put the whole system in an acceptable weight range.
 

rcktnut

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30 bucks or so is very cheap compared to what rocketry electronics cost 25 years ago.
Along with a heck of a cost reduction now, the size of the electronics has also been reduced dramatically.
 

neil_w

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This hobby is starting to add up quick. If i spend $20 on a airframe, idc if i lose it. But once i add $30 in alt., then i need to insure it with another $100 in gps. There has to be a more cost effective way. 🤔
Trackers are great, but I don't most people would consider recovery of a $30 altimeter to be motivation to use one. Especially on smaller rockets you don't want to load them down with too much electronics. Throwing in an FS Mini or a Firefly into an LPR rocket is pretty easy, and not worth sweating over. Also remember that trackers fail and rockets are lost anyway.

At some point you have to be accept the possibility that you're gonna lose stuff, even while taking all reasonable precautions against that happening.
 

PayLoad

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I have FS Minis in every rocket I fly, plus a few spares (never know when they'll be in stock) Read what neil said above
 

BEC

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FireFly or FS Mini. FireFly is the simplest to use and also the least expensive at ~$25. FS Mini is much more capable, but until some more parts arrive there won’t be any more of them (so a month or two). As Neil said, these are generally not worth the effort to also add a tracker. That’s really the whole point of one that’s this inexpensive.

If you’re flying something big enough to even fit a tracker, then you have lots of options including the Estes unit...which gives good data when it detects a launch. Quick liftoffs and big static ports are your friend if you’re using one of those. But much better than the Estes unit is Jolly Logic’s AltimeterOne or AltimeterTwo.

As for that sensor on Amazon: as any altimeter makers will tell you, the hardware is the (relatively) easy part. The software is where the work is.
 

bobbyg23

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Flightsketch.com. The mini. Awesome altimeter
 

AtomicStorm

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So the fs mini, what powers it? Do you have to make a battery box or something?
 

AtomicStorm

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I would like a recharchable battery on the inside ovcourse with a quicklink on the side of the rocket i can just plug into and charge it with a power on switch like my rc airplane has
 

rklapp

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All being said, you’re very likely to lose the Comanche 3. I would launch it first then if you get it back, launch it again with the altimeter. Or just put C6 and D12 in it and hope it doesn’t reach orbit...
 

Mike Haberer

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The Estes altimeter is pretty unreliable but iirc it does fit a BT50 tube (Comanche 3 is BT50). I would look into the Perfect flight Firefly for altitude only or even better the Flightsketch Mini as it does logging and acceleration data . The FS Mini and Firefly are both priced near the Estes Altimeter in price but are magnitudes more reliable. Cheapers is harder to find but the Eggtimer Quark does altitude with dual deployment but no logging of data, the Eggtimer also requires soldering as all Eggtimer products are kits, for apogee only deployment Eggtimer offers the Eggtimer Apogee.
A plug for the Eggtimer Apogee, I flew it for the first time last month. Awesome. I'm incorporating it into all of my SD scratch builds of BT60 through BT80 (might be able to do BT55 as well), with motor backup. I'm tired of having over-stable rockets lawn dart or zipper on windy days; apogee deployment mitigates most of the risk. It's dirt simple to solder and operate. It's small enough that I can put both the Apogee and Eggfinder in the nose cone of BT80 or 3" bird side by side.
 

prfesser

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Anyone ever used something similar to this?
I haven't, but how fast does it sample? What's the uncertainty in altitude readings? Can it deploy a drogue and/or main? Those are questions you may want to ask the manufacturer. Fifteen bucks for a unit that will require additional parts and won't dual-deploy isn't much of a bargain.

As others have pointed out, the Eggtimer Quark is inexpensive, it will fit in a BT20 with some minor changes in assembly, it does dual-deploy, and there are some very good and very reasonable "assemblers" on this forum if you don't feel like assembling it yourself.

Unless...designing and programming a custom altimeter is something you hanker for. I let others do that, I build rockets. Even fly them occasionally. :)

Best -- Terry
 

tOD

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PerfectFlight Firefly @$24.95 would be another choice in a ready to fly unit.
 

cerving

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Which altimeter you choose often comes down to what kind of data and other features you are looking for. That's why there are so many of them, with different features: deployments, datalogging, wireless, telemetry-capable, airstart-capable, GPS-capable, etc. Look at the "Altimeter Comparison Chart" at the top of this section, that might help you... although some of the altimeters are now OOP, and it doesn't have some of the non-deployment altimeters.
 

rklapp

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I'm tired of having over-stable rockets lawn dart or zipper on windy days; apogee deployment mitigates most of the risk.
How does it mitigate?

IIRC, the Firefly has beeps but no data logging like the FS Mini.
 

BEC

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Firefly has an LED - it blinks out the digits rather than beeping them. With the Field Data Display you can get some statistics, but not full flight data.
 

neil_w

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How does it mitigate?
A non-vertical trajectory caused by excessive weathercocking will reach apogee earlier than expected, and therefore motor eject is likely to be late, maybe very late.

Apogee eject ensures optimal deployment regardless of the flight trajectory. However, electronic deployment is not really an appealing option for us LPR flyers.
 
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