2.6 and 3" birds, do you always run dual altimeters?

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Buckeye

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Purely anecdotal, but I have never seen a commercial altimeter fail.
I've been failures that are all user induced or could have been eliminated with just a little ground testing...cheap battery, underpowered battery, cheap battery connectors, incorrect programming, poorly secured battery, undersized ejection charges. The list goes on, but the common trend is user error.
+1 to all this ^

Even after some hard landings and water landings, my altimeters continue to work just fine. I always ground test them after such events. They are surprisingly robust devices.

If you don't know the root cause of bad deployments, then you are potentially doing the wrong thing twice with two altimeters. More altimeters = more complexity = more design time = more prep time. Not worth it for my model rockets up to 4" and a couple hundred dollars. Maybe if I build a big, expensive project, I will change my tune.
 

Rocketjunkie

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Purely anecdotal, but I have never seen a commercial altimeter fail.
I've been failures that are all user induced or could have been eliminated with just a little ground testing...cheap battery, underpowered battery, cheap battery connectors, incorrect programming, poorly secured battery, undersized ejection charges. The list goes on, but the common trend is user error.
I've had a few. Raven 1 23rd flight in EZI with J500. Ballistic recovery, completely destroyed. Formula 98 on K160 and Raven 2 4th flight. Ballistic recovery, was able to solder wires to power pads and get data. Never detected liftoff. Motor provided over 5 g's for at least 5 seconds. 7.5" Goblin on Rx L750 and Strattologger CF. Ballistic recovery, was able to get data from altimeter. Intermittent power during burn of sparky motor, then lost power completely shortly after burnout. Hold up cap lasted until shortly before apogee. 9V snap was off the battery and not mashed like the battery.
I fly one altimeter except in high performance rockets. The Cloudbusters were before electronics and used motor ejection.
 

Cameron Anderson

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I've had a few. Raven 1 23rd flight in EZI with J500. Ballistic recovery, completely destroyed. Formula 98 on K160 and Raven 2 4th flight. Ballistic recovery, was able to solder wires to power pads and get data. Never detected liftoff. Motor provided over 5 g's for at least 5 seconds. 7.5" Goblin on Rx L750 and Strattologger CF. Ballistic recovery, was able to get data from altimeter. Intermittent power during burn of sparky motor, then lost power completely shortly after burnout. Hold up cap lasted until shortly before apogee. 9V snap was off the battery and not mashed like the battery.
I fly one altimeter except in high performance rockets. The Cloudbusters were before electronics and used motor ejection.
Not to discount your failures, just looking for clarification...

Never used the Raven 2, was it baro armed it accel armed at launch? Possible failure to detect launch due to improperly sized vent holes?
Strattologger sounds like the battery disconnected in flight since the batter clip wasn't smashed, would you agree?
 

Rocketjunkie

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Not to discount your failures, just looking for clarification...

Never used the Raven 2, was it baro armed it accel armed at launch? Possible failure to detect launch due to improperly sized vent holes?
Strattologger sounds like the battery disconnected in flight since the batter clip wasn't smashed, would you agree?
Ravens use the acceleration to detect liftoff. IIRC, 3 g's for at least 1/2 second. I did have the apogee detect set to barometric.
Yes, the Strattologger failure was due to battery disconnect. First time I had flown it on a large sparky motor. I now tape the clip on to the battery to prevent this.
 

DRAGON64

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With recovery being controlled by an altimeter, and smaller birds like 2.6" and 3" birds do you always use dual systems, or are you comfortable with a single proven altimeter?
First of all, whatever you decide, If possible I would consider making the altimeter(s) dedicated to the rocket. Basic dual event altimeters are about $50 a pop, in most cases, cheaper than a quality parachute.

For rockets in the 2.6 to 3" range, I would use a single unit with motor back up (if relevant), unless the you are planning extreme altitudes, then a dual altimeters would be a good fail safe option (not read as fool proof). And to, I would add a tracking system for a rocket flown to higher altitudes where visual tracking is limited.

There are some good 3D printed options for AV bays; two 54mm sleds w/ battery holders should fit inside most 2.6" couplers Maybe not an Aerotech kraft tube coupler). Have a look at Additive Aerospace for 3D printed options.
 

Dustin Lobner

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Haven't read the rest of the posts, but I did dual on a 3" that I flew Memorial Day weekend, mostly because it was a challenge to shoehorn two altimeters into that small space. Fun challenge, it worked, and everything flew great.
 

Handeman

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I usually only use one altimeter on 3" or less, but I do have one 3" w/54mm MMT that has dual. Actually, I have some 4" with single altimeters.

I've been flying altimeters since '07 and I'm still not convinced that dual altimeters are really needed on anything short of L3, but I think it's an individual choice.
 
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