question about altimeters

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rocketsonly

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Has anyone used the Perfectflite Alt15k/WD altimeter (no deployment)? Have you all noticed how sometimes the altimeter will read the same altitude when the rocket is traveling upwards? And sometimes a reading may be higher than the previous reading when coming down?

Is this normal for all altimeters or is it just the Alt15k/WD altimeter? Do the BlackSky altimeters do the same thing?

Any feedback would be greatly appreciated .

Thanks.
 

llickteig1

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I am not sure what you're trying to ask.

Is you observation during groung testing, read from the download or what?

You might drop a mail to PerfectFlite with your question. I have always had their products perform as expected and I own MAWD and Alt15k/WD.

--Lance.

------

Also, consider losing the red background on the rocketguts website. Marketing people will tell you red is bad. That may or may not be true, but it definitely makes rocketguts.com visually unpleasant to visit.
 

solrules

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I know that the Perfectflite MAWD altimeters do something like that. The Ozark Aerospace ARTS does the same thing as well. From this, I would imagine that it happens with all altimeters. I guess the altimeter is sampling the barometric sensor faster than it can change, errors in the 12 A2D converter, or something else.

When the rocket is going down, a small wind gust could push more air into the sensor, making it think it is lower than it actually is.

Here is what he is talking about (for example)

Code:
TIME        ALT

2.05        1000
2.1          1000
2.15        1000
2.2          1025
2.25        1025
 

rocketsonly

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Originally posted by solrules
I know that the Perfectflite MAWD altimeters do something like that. The Ozark Aerospace ARTS does the same thing as well. From this, I would imagine that it happens with all altimeters. I guess the altimeter is sampling the barometric sensor faster than it can change, errors in the 12 A2D converter, or something else.

When the rocket is going down, a small wind gust could push more air into the sensor, making it think it is lower than it actually is.

Here is what he is talking about (for example)

Code:
TIME        ALT

2.05        1000
2.1          1000
2.15        1000
2.2          1025
2.25        1025
Yup, that's what I meant. I'll see what Perfectflite has to say.
 

phaar

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Well, I do not know exactly what you are saying but, when my team was at TARC, our rocket was ready and set up on the pad. The altimeter was taken extra special care of. We stand back, hold our paddle up, and get ready fro the launch when we heard the beep of the altimeter go back to a previous flight we had. We were very nervous at the time and this just put us over the edge. We quickly put down the paddle and ran to our pad(getting yelled at in the process) and checked out the altimeter. We cleared it and everything was fine. We stepped back, and low and behold, it happened again! And again and again. Yes, this freaked us out. The only good part was that if it did do it again on the way up, it would put us 15 feet below target altitude, which in our minds, was very good. So, we stepped back one last time and finally got it off the pad, thanks to the very helpful gentleman at the pad. We got 2 feet higher then the previous recording so that was good. We figured out later though, it had been the wind in that was rushing through the holes in the side of the payload, changing the pressure, that had kept clearing it. The whole time we were standing in line we were so afraid it would clear again, but luckily it never did. Now that is probably the longest answer you have ever been given, but I hope it helped. Actually, I do not even know if that is what you were talking about looking back, but I am posting it anyway because I did not want to feel I wasted my time...:kill:
 

Hospital_Rocket

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The owners of PerfectFlite are members of CATO and I pinged them outside the forum to see if they can help you out.

A
 

cls

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my perfectflite MAWD and 15k both do that, as do both the baro and the accell on both of my GWiz MCs. none of these are accurate to the foot or meter, I'd be surprised if they were within 15 meters or 50 feet.

the stepping up in numbers has to do with sampling rate (how often the computer is reading the instrument), and the resolution of the measurement. google for Nyquist and see what he has to say about it.
 
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