My little altimeter

Wildman Rocketry
rocket sok
Onebadhawk
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But that is the beauty of it.
You are not restricted by the MFG supplied battery.
Click to expand...

True, but I suspect that a single Lipo cell would not provide enough voltage for the PicoAlt to work, which was the closest competitor I was aware of as far as mass goes. Looking more closely at the pictures on your site, I see that you have a boost converter to get 5V for your altimeter. When I decided not to go that route originally, I was concerned that it would take up too much room, but I see that yours is still pretty small. How did that work out for you? How noisy is it?

I'd still like to know more about your altimeter, because I want to be sure not to make any inaccurate claims about the Parrot being the lightest.

As for market niche, I made the altimeter that I wanted for myself, and I may only sell a handful. Fortunately, this isn't my day job.
 
Adrian A said:
True, but I suspect that a single Lipo cell would not provide enough voltage for the PicoAlt to work, which was the closest competitor I was aware of as far as mass goes. Looking more closely at the pictures on your site, I see that you have a boost converter to get 5V for your altimeter. When I decided not to go that route originally, I was concerned that it would take up too much room, but I see that yours is still pretty small. How did that work out for you? How noisy is it?

I'd still like to know more about your altimeter, because I want to be sure not to make any inaccurate claims about the Parrot being the lightest.

As for market niche, I made the altimeter that I wanted for myself, and I may only sell a handful. Fortunately, this isn't my day job.
Click to expand...

3.7V is perfectly fine for some PICO models.
The boost converters can be noisy so you have to watch your grounds. But I had to use a step-up since the power source is a 1.2V battery.

The market is just too small for any of the electronics vendors to make a living off it.
But it's nice to see new exciting products hit the market.

Robert
 
I am hoping that the constructrion techniques and specifications for this altimeter have been shared with Santa's elves as it is one of the top items on my list I sent to him.
 
I am hoping that the constructrion techniques and specifications for this altimeter have been shared with Santa's elves as it is one of the top items on my list I sent to him.
Click to expand...

Thanks, and not to worry. I'm actually an elf myself, and my shift at the North Pole starts next week. :santaclaus:

And the picture of the fingers holding a Parrot? That was one of my human friends holding one for the camera.
 
Congrats Adrian - sounds like this will now become my altimeter of choice to ride along and provide data in my rockets. Good luck setting that F record btw, now that the alt is official...
 
Adrian A said:
True, but I suspect that a single Lipo cell would not provide enough voltage for the PicoAlt to work, which was the closest competitor I was aware of as far as mass goes. Looking more closely at the pictures on your site, I see that you have a boost converter to get 5V for your altimeter. When I decided not to go that route originally, I was concerned that it would take up too much room, but I see that yours is still pretty small. How did that work out for you? How noisy is it?

I'd still like to know more about your altimeter, because I want to be sure not to make any inaccurate claims about the Parrot being the lightest.

As for market niche, I made the altimeter that I wanted for myself, and I may only sell a handful. Fortunately, this isn't my day job.
Click to expand...

but can it handle 240g's?
 
Possibly. The standard sensor can handle 70, but I have no doubt that the unit itself could take 240. With a custom sensor, it would probably be fine.
 
but can it handle 240g's?
Click to expand...

None of the units in stock now can measure more than about 70, though Parrots have survived lawn darts to hundreds of gees. In the next batch I get assembled I'll sprinkle in some of the 250 g single-axis sensors, since they are pad-compatible with the +/-70, +/- 35 G dual-axis sensors I'm using now.
 
Congrats Adrian - sounds like this will now become my altimeter of choice to ride along and provide data in my rockets. Good luck setting that F record btw, now that the alt is official...
Click to expand...

Thanks, Chris. After F record attempt rocket #3 went so high (8422 ft) in November, losing F rocket #4 entirely along with my beeline and a Parrot has make me kind of discouraged about the F record at the moment. Maybe next spring I'll build F attempt #5. With a Parrot, a beeline and an F10, the TRA F record (6785) should be easy pickings, but I've been cutting it too close in a few areas in order set the bar as high as I could, rather than just beating the record. The G record is up for grabs too, using the 24mm Ellis G37. And a G37 - E6 2-stage rocket could go north of 13k, while staying within the G impulse limit.
 
do you pot your altimeters from the factory or is that a user required modification?
 
My failure modes were:

#1: Fins too small (used Rocksim instead of Barrowman algorithm)
#2: Lateral mass offset
#3: Shock got cut because of the way I mounted it next to a sharp edge. Nosecone found via beeline after a tumble recovery from 8422 feet
#4: (using the same avionics setup from #3) was most likely a short caused by aluminum tape I was using for shielding. The Parrot and Beeline in their standard configurations play nicely together (see example Parrot data on Featherweight altimeter website, which was taken on cjl's 2-mile cirrus dart flight with a Parrot and Beeline back-to-back), but I experimented with cutting down the beeline antenna in half, which apparently generated some other frequencies that could couple into the Parrot without the shielding. I can't claim I didn't have a warning, though, because I got a dropout in the transmission when it was on the pad.
 
do you pot your altimeters from the factory or is that a user required modification?
Click to expand...

I've done all the testing so far without any potting. I do glue down the buzzer and the button after assembly with some epoxy, and that has been sufficient for survival from a 700 foot ballistic lawn dart, and nosecone tumble recoveries from 4300 and 8400 feet. The only flight that a Parrot hasn't survived was my F record attempt #1, above, which straighted out in the downward direction after enough fuel burned off, and impacted more than 6" into hard-packed dirt. The beeline didn't survive that one either, though both lipo cells were intact.
 
Adrian A said:
I've been informed by Tom Rouse that the Parrot altimeter is now certified for use in setting Tripoli altitude records. :cheers:
Click to expand...
Adrian

How are you performing the calibration to insure that each altimeter is calibrated accurately for absolute pressure? Do you have an altimeter calibration chamber to perform this function?

At a minimum I would think you need a vacuum chamber and a NIST traceable standard pressure transducer to perform the calibration on each altimeter.

Bob
 
Bob,

Please see the Parrot User's manual, which has details of the calibration and verifications.

But to summarize, each Parrot altimeter is individually calibrated at two temperatures in an altitude chamber, using a temperature-controlled pressure reference that I calibrated using USGS landmarks. I then validated the procedure by driving a production-calibrated Parrot over known altitudes. I also ran all the first batch of Parrots through a simulated flight in the same chamber at the same time, to check the calibration repeatability, which was 0.25% 1-sigma in the pressure transducer scale factor.

Here is data from the production unit calibration validation:

The red dots are landmarks along I-70 that I identified on USGS topo maps. This particular Parrot model read about 0.6% low in scale factor, which is within the expected variation due to weather-induced barometric pressure differences between these widely-spaced locations. I'm thinking about doing another validation when the Mt. Evans road opens up again in the spring, which provides a 7000 foot span within just a few miles as the crow flies, and less than an hour's drive, in order to reduce the uncertainty caused by weather system variations.
 
Adrian A said:
Bob,

Please see the Parrot User's manual, which has details of the calibration and verifications.

But to summarize, each Parrot altimeter is individually calibrated at two temperatures in an altitude chamber, using a temperature-controlled pressure reference that I calibrated using USGS landmarks. I then validated the procedure by driving a production-calibrated Parrot over known altitudes. I also ran all the first batch of Parrots through a simulated flight in the same chamber at the same time, to check the calibration repeatability, which was 0.25% 1-sigma in the pressure transducer scale factor.

Here is data from the production unit calibration validation:

The red dots are landmarks along I-70 that I identified on USGS topo maps. This particular Parrot model read about 0.6% low in scale factor, which is within the expected variation due to weather-induced barometric pressure differences between these widely-spaced locations. I'm thinking about doing another validation when the Mt. Evans road opens up again in the spring, which provides a 7000 foot span within just a few miles as the crow flies, and less than an hour's drive, in order to reduce the uncertainty caused by weather system variations.
Click to expand...

Our family has a house in silverthorn :D
 

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