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.
 

Ray Lecture

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I have been starting to use that Altimeter also and notice that the rocket arcs over and starts coming down before it separates. I looked at the flight data and the drogue event is after apogee. So I looked at the settings and there is a drogue delay that was set to 1sec. I tried to set this to 0 sec but it reverted to 1. I could set it higher. Is 1 the lowest you can set it?
 

QFactor

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If you
I have been starting to use that Altimeter also and notice that the rocket arcs over and starts coming down before it separates. I looked at the flight data and the drogue event is after apogee. So I looked at the settings and there is a drogue delay that was set to 1sec. I tried to set this to 0 sec but it reverted to 1. I could set it higher. Is 1 the lowest you can set it?
If you're using the mDACS program, in the RRC3 Settings menu there is the "Deployment Mode" on the right side of the menu. You want to select "Primary Dual Deploy Mode". This has the drogue coming out at apogee. The "Drogue Delay" will still show 1 second, but that delay will be disabled.
 

Ray Lecture

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Yes the mode was set for Primary Dual Deploy. And reading from the manual today I see that the the drogue delay is ignored in that mode. Flight data showed apogee at around 4.5 seconds and the drogue event at 7.6 sec and fired 30 ft below apogee and falling at 15 fps.

Since I am new to this for this flight the engine charge is what separated the rocket with a 4 sec delay and the RRC3 was there as a test.
 

QFactor

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Yes the mode was set for Primary Dual Deploy. And reading from the manual today I see that the the drogue delay is ignored in that mode. Flight data showed apogee at around 4.5 seconds and the drogue event at 7.6 sec and fired 30 ft below apogee and falling at 15 fps.

Since I am new to this for this flight the engine charge is what separated the rocket with a 4 sec delay and the RRC3 was there as a test.
Did you have charges on the RRC3, or did you just send it as a ride-along?
 

QFactor

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I had the RRC3 live with just the drogue charge.
You were using the RRC3 and motor charge in a single deployment setup? The drogue was actually the Main? Trying to get a clear picture of the setup and event sequence.
 

Ray Lecture

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Yes I am building up to dual deploy, but was attempting a mid body separation with a large chute in the drogue position. Using both the engine and the RRC3 charges with one backing up the other. The flight data shows some turbulence around 4 sec which I assume was the motor charge firing. Then apogees was around 4.5 sec. Once it arched over and was coming down we heard the drogue fire and the date shows that happened at 7.6 sec which was well after apogee.
 

QFactor

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Yes I am building up to dual deploy, but was attempting a mid body separation with a large chute in the drogue position. Using both the engine and the RRC3 charges with one backing up the other. The flight data shows some turbulence around 4 sec which I assume was the motor charge firing. Then apogees was around 4.5 sec. Once it arched over and was coming down we heard the drogue fire and the date shows that happened at 7.6 sec which was well after apogee.
If your rocket is a kit - which one? And what motor did you use?
 

Ray Lecture

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It is a scratch 2.6" scaled up Hi Flier. I was looking at logs from the previous test flights and they all showed a drogue event right at apogee. So I thing I have the setting ok. I am now thinking that the turbulence from the ejection from the motor charge may have kicked off some filtering in the SW that delayed the drogue charge. I think next time I will use a longer delay on the motor and let that serve as the backup to the RRC3
 
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