RRC3 flight data cut

[Kido-29]

We just used the RRC3 alongside our DIY flight computer recently for our Rocket, everything worked well, the drogue ejected at apogee and main chute deployed too. When gathering data, I noticed that the max altitude recorded is different, in my flight computer, it said 1590 feet(AGL) and the RRC3 recorded 1541 feet(AGL). at first I thought that it was just a difference in pressure readings, but when I checked the RRC3 DATA, it landed at -49 feet(AGL), adding that to 1541feet, we can get 1590 feet, which coincides with our main flight computer(DIY). the rocket landed at the same elevation as the launch +/- 2 feet for the launch rail. one thing's for sure, it was not a 49 feet difference. is there an issue with RRC3 where the data recorded only starts after a few moments after launch?

 

[Banzai88]

We just used the RRC3 alongside our DIY flight computer recently for our Rocket, everything worked well, the drogue ejected at apogee and main chute deployed too. When gathering data, I noticed that the max altitude recorded is different, in my flight computer, it said 1590 feet(AGL) and the RRC3 recorded 1541 feet(AGL). at first I thought that it was just a difference in pressure readings, but when I checked the RRC3 DATA, it landed at -49 feet(AGL), adding that to 1541feet, we can get 1590 feet, which coincides with our main flight computer(DIY). the rocket landed at the same elevation as the launch +/- 2 feet for the launch rail. one thing's for sure, it was not a 49 feet difference. is there an issue with RRC3 where the data recorded only starts after a few moments after launch?

Not uncommon for an RRC3. There is a slight delay in recording due to the Arming Altitude, which is user configurable. Default is 300 feet. Once Launch Detect = YES, it shifts data that it has saved in the short term file to the "Flight File", which may or may not include the ground reading, depending on how large your "Arming Altitude" setting is.

From the manual: Once the altimeter has reached its “Arming Altitude” (ie. rocket is launched), it will write a 1 second (20 sample) pre‐launch
ring buffer to flash memory to capture its pre‐launch pressure data.

I suggest that you download the manual for the RRC3 from the MW sight and use the search function to find Arming Altitude and read up on it.

 

[Kido-29]

Not uncommon for an RRC3. There is a slight delay in recording due to the Arming Altitude, which is user configurable. Default is 300 feet. Once Launch Detect = YES, it shifts data that it has saved in the short term file to the "Flight File", which may or may not include the ground reading, depending on how large your "Arming Altitude" setting is.

From the manual: Once the altimeter has reached its “Arming Altitude” (ie. rocket is launched), it will write a 1 second (20 sample) pre‐launch
ring buffer to flash memory to capture its pre‐launch pressure data.

I suggest that you download the manual for the RRC3 from the MW sight and use the search function to find Arming Altitude and read up on it.

Hey, thank you, that was my bad not noticing that in the manual, thank you for clarifying, have a great day

 

[pathtouch]

A word of caution on lowering the arming altitude too low. I had an Eggtimer Quantum and I set to 100 feet (default is 200). Turns out my first flight with it on a very windy lake bed, in a large AV bay with four vent holes, a gust of wind lowered the ambient pressure enough to simulate a 107 foot flight and I blew the drogue out on the pad before the even launching the rocket.

So long story short, I wouldn't go any lower than 200 feet for arming altitudes. maybe 150 if you know it won't be windy.

 

[cerving]

We recommend using 200' launch detect just because of that... it's impossible to tell the pressure change due to a sustained gust from a launch, so a 100' launch detect can be a little dicey if you're flying in a windy place. If you're using a Proton, you can set the baro launch detect a bit higher than that, maybe 300'... the accelerometer's launch detect will almost always happen first.