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Late drogue deployment using RRC3 altimeters

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pensfan1

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We are flying to close to 4000" with redundant electronics. On our first flight we noticed that the first drogue charge fired late as well as the second drogue charge. Both seemed to fire the same amount past where they should have fired. Has anyone else seen these issues with that altimeter? This is our first time using that altimeter, we have used Perfectflite for years without issue.
 

Buckeye

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4000 inches, eh? That's not enough to trigger a flight by the altimeter. ;)

How do you know when they "should" have fired? Many altimeters are programmed to fire at apogee + 1 second. I believe the RRC3 is a recording altimeter, so plot the data and see what is happening.
 

Titan II

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Have many RRC3s. All charges fire as programmed. As Buckeye said, look at your data.
 

Jee3300R

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I’ve noticed that some altimeters seem to fire momentarily after apogee or atleast it looks that way from onboard videos (raven, adept22, ARTS, etc.). However, from my experience both the RRC3 and SLCF fire at what looks to be exactly the right time from the onboard.
 

Exactimator

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If you review the data as others have suggested and find the charges fired after apogee:

The RRC3 has a programmable delay when it's used for redundancy (you definitely need the delay so you don't set of both full charges at once). Since your set-up is redundant, it's possible both altimeters accidentally got set with the delay. I suggest double-checking the settings.
 

QFactor

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We are flying to close to 4000" with redundant electronics. On our first flight we noticed that the first drogue charge fired late as well as the drogue charge. Both seemed to fire the same amount past where they should have fired. Has anyone else seen these issues with that altimeter? This is our first time using that altimeter, we have used Perfectflite for years without issue.
Did you program the RRC3's thru the dip switches or the mDACS program? If you used mDACS, you can print out how you programmed the RRC3 - as long as you saved the file. Post the file if you can. They we can see how the RRC3's were set up.

And if you're saying both units fired charges at the same time, it sounds like you some how programmed both units them with the same conditions.

And like "Buckeye" pointed out, the 4000" (333') barely triggered the "arming" of the RRC3. Its default arming altitude is 300'.
 

Handeman

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Please make certain your electronics has sufficient venting to the outside air and not blocked by something. Hole size should be based upon the volume of the compartment housing the electronics.
This is great advice. If the holes are too small (bigger is better), it will take until after apogee for the higher pressure inside the av-bay to equalize and indicate apogee.
 

cerving

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Unless your AV bay is completely airtight (which is actually pretty unlikely), the vent hole size isn't going to matter very much for descent deployments. You're moving so slowly that the distance between actual apogee and when your pressure equalizes to determine apogee is insignificant, possibly not even measurable.
 
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