Post your Raven FIPa files here

[Adrian A]

Something is wrong with primary Raven 3. Accelerometer reports 1.67 s burn for 4.9 s M1520. Baro is flat during burn, then goes negative (-1525') before under reporting apogee by ~3000' vs secondary. Primary main pyro voltage drops out at 87 s. Then primary stops recording after 131 s versus 157 s for secondary as if Raven 3 was fooled into thinking it had landed or had powered down during descent.

I don't see anything amiss in the data with either data file, other than the descent rate doesn't change much after the main firing for either flight. They don't match because they were recorded from two different flights.

 

[Tetrahedron]

Hi to all Raven owners (and potential owners)-

Does it sound like a good idea to post flight data files for all to see and share? This stuff fascinates me and I think there's a lot of learning to be had.

Examples of both good flights, where everything went well, and not-so-good flights are welcome. I think both kinds can be learned from and if we start sharing our experiences we'll all learn faster. Could lead to some interesting discussions.

Sound good?

I would if I could but mine crashed and the data is still in the chip that survived but I can't get the data out...

THX, John

 

[WoShuGui]

I don't see anything amiss in the data with either data file, other than the descent rate doesn't change much after the main firing for either flight. They don't match because they were recorded from two different flights.

I wondered if that was possible. Is the negative baro mach pressure? An impressive example if so.

 

[Jimmy F.]

The flight files you posted are from two different flights. If you have been using both of these Ravens together for more than one flight, I think you'll find that at least one of the posted flights has a match still saved in the data on the other altimeter.

You are correct Adrian
I downloaded the previous flight as the primary
Here are the correct files
Much better match in data set

View attachment Powerslave CTI M1520BS primary.FIPa

View attachment Powerslave CTI M1520BS secondary.FIPa

 

[Jimmy F.]

I wondered if that was possible. Is the negative baro mach pressure? An impressive example if so.

That flight was from my PR 4" Patriot with a CTI K1440
Funny thing is I had deployment issues with that flight too.
Guess I better re-evaluate my recovery systems.
This one had cable cutter on board, but the igniter wire pulled loose.

View attachment q Patriot CTI K1440WT.FIPa

 

[Adrian A]

I wondered if that was possible. Is the negative baro mach pressure? An impressive example if so.

It's a pretty common phenomenon to get some significant pressure transients during liftoff. One common mechanism is that the parachute slides back in the upper av-bay like a piston, and any leakage paths into the av-bay look like a decrease in altitude. Just the accelerating air column can be also significant on high-G flights. Imagine you have a 5-foot long, sealed air column above the altimeter, and you accelerate at 50 Gs. The increase in air pressure at the altimeter just from accelerating the mass of air above the altimeter will be equivalent to 250 feet.

 

[Jimmy F.]

Posting this file for maxvelocity, cause he asked me to.
This one has some really crazy data...
I will let him elaborate if he wants to

 

[maxvelocity]

Posting this file for maxvelocity, cause he asked me to.
This one has some really crazy data...
I will let him elaborate if he wants to

Adrian,

I'm curious what went wrong here? Does my accelerometer need to calibrated or is there something wrong with the unit?

 

[Adrian A]

Adrian,

I'm curious what went wrong here? Does my accelerometer need to calibrated or is there something wrong with the unit?

The on-board velocity measurement looks reasonable, and the accel-based apogee detection was right on the money, so it's not a problem with the in-flight functionality. It looks more like something got messed up in the download or possibly the data recording. Try downloading the file again.

 

[bobkrech]

I wondered if that was possible. Is the negative baro mach pressure? An impressive example if so.

The pressure transients are real. As you supersonics through Mach from subsonic a shockwave moves from the aft end of the rocket forward to the nosecone. As you as you approach Mach the first pressure drops and then jumps up as the shock wave passes and then relaxes to ambient. The reverse happens coming from supersonic through Mach. There will be a rise in pressure as the rocket drops toward Mach followed by a pressure drop after the shock wave passes and the pressure will relax back to normal.

Bob

 

[billspad]

This flight had all kinds of interesting things happen. The rocket is 4" diameter and 202 ounces. The motor was a CTI J330. Open Rocket predicted 1900 feet and Smart Launch 1600 feet.

Besides the Raven there was an Adept 22.

The axial acceleration matches the thrust time curve of the motor up to about 1.75 seconds where something strange happened. I recall hearing a sort of crackling sound about that far into the burn. There's a weird downward spike in the barometric altitude at this point. Then things go normally with the Raven firing the apogee charge and the rocket separating and the drogue deploying. At around 300 feet (which is what I think I set it for) the main charge fires. I was uncharacteristically conservative on the black powder and the main did not deploy. When I recovered the rocket the Adept was beeping out continuity on the two charges and was apparently still waiting for liftoff.

But wait, there's more. As I was examining the banged up altimeter bay I noticed a small rectangular multi legged insect on my table that turned out to be a chip from the Raven. The marking on the board where it was says U$5. Considering the location I assume it has something to do with the output to the third charge that I wasn't using. The chip next to it has also lifted off the board.

The Adept 22 is still waiting for liftoff and when I power it up it tells me that the last altitude was 994 feet which may have been the last successful flight it had but I don't remember.

It's not easy to see in the attached photo but the nozzle from the J330 looks very eroded.

Any thoughts on any of this?

View attachment 91513.FIPa

 

[Adrian A]

This flight had all kinds of interesting things happen. The rocket is 4" diameter and 202 ounces. The motor was a CTI J330. Open Rocket predicted 1900 feet and Smart Launch 1600 feet.
...

Any thoughts on any of this?

The motor looks like it got blocked and spit something out that caused the G spike when it cleared. Maybe it affected the throat diameter after that too? It's kind of odd that the motor thrust went down by more than 2x after the jolt. The dip in the baro sensor may be from your chutes shifting back under that 35+ Gs and some of that pressure leaking back into the av-bay. I wonder if that also affected your main deployment.

Looks like you hit pretty hard without the main, and in addition to shearing off an output FET from the Raven, it also may have broken the baro sensor. Either that or something got out of whack on the data recording after the impact. Check your live data the next time you've connected via the Featherweight Interface Program to see if you're getting out reasonable baro data from the sensor.

 

[billspad]

The motor looks like it got blocked and spit something out that caused the G spike when it cleared. Maybe it affected the throat diameter after that too? It's kind of odd that the motor thrust went down by more than 2x after the jolt.

That's what I was thinking. I don't have another J330 to compare it to but that drop off would be consistent with the throat getting bigger.

The dip in the baro sensor may be from your chutes shifting back under that 35+ Gs and some of that pressure leaking back into the av-bay. I wonder if that also affected your main deployment.

There's not a lot of empty space in the booster section (or the parachute compartment for that matter) so some leakage into the altimeter bay isn't a huge surprise although I thought I did a pretty good job of sealing it. In the parachute compartment the deployment bag is up against the charges. I'm really surprised it didn't push the nose cone off. I was trying to avoid the large bang I usually with a generous charge and I evidently went a little to far in the wrong direction.

Looks like you hit pretty hard without the main, and in addition to shearing off an output FET from the Raven, it also may have broken the baro sensor. Either that or something got out of whack on the data recording after the impact. Check your live data the next time you've connected via the Featherweight Interface Program to see if you're getting out reasonable baro data from the sensor.

I'm going to fly it in something with motor deployment next week just to test it. After what it's been through (this is not the first time it's hit hard) I don't think I should trust it. I'm sure I'll be ordering a new one soon.

 

[Sailorbill]

Here are two recent FIP files.
The first is from the Raven 2 in my 6" Ultimate Endeavor "Phred" on a 75mm CTI L1115 Classic at AIRFest19 09-02-13 in Argonia, KS.
View attachment L1115C09-02-13.Phred.AIRFest19.FIPa
0
The second is from the Raven 1 in my 4" LOC EZI-65 Electronics upgraded rocket on a CTI J330 Green3 at the T.H.O.R. 09-21-13 in Jansen, NE.

View attachment EZI-65-08-21-13-J330-a.FIPa
I just noticed this file name says 08-21-13 but it really is for the flight on 09-21-13 :blush:

 

[billspad]

The second is from the Raven 1 in my 4" LOC EZI-65 Electronics upgraded rocket on a CTI J330 Green3 at the T.H.O.R. 09-21-13 in Jansen, NE.

View attachment 146645
I just noticed this file name says 08-21-13 but it really is for the flight on 09-21-13 :blush:

That's what mine should have looked like.

Do you remember what the reload looked like after you removed it from the casing? This is what mine looked like. I've flown a couple J330s before I don't remember it looking like that.

 

[Sailorbill]

That's what mine should have looked like.

Do you remember what the reload looked like after you removed it from the casing? This is what mine looked like. I've flown a couple J330s before I don't remember it looking like that.

View attachment 146670

Mine wasn't that bad but it did have a significant burn through about 1.5" below the delay grain. It didn't hurt the case but it was a bee itch to clean up.

 

[CarVac]

That's what mine should have looked like.

Do you remember what the reload looked like after you removed it from the casing? This is what mine looked like. I've flown a couple J330s before I don't remember it looking like that.

View attachment 146670

Usually they're more beat-up at the head end.

 

[billspad]

The burn through on mine was closer to the nozzle and it was not a lot of fun to clean. There's still some residue but I tried another reload and it fits so I'm going to leave it rather than risk screwing up the anodizing.

 

[HaackIt]

I just dug out the FIPa from last year's TCC DairyAir drag race. ~6lb carbon fiber / cardboard / balsa Nike on a K2045.

View attachment nike-dragrace.FIPa

Videos:

[YOUTUBE]RIVVXbZsRvY[/YOUTUBE]

[YOUTUBE]ty31xtNHVyY[/YOUTUBE]

 

[Adrian A]

Wow, 30+ Gs of deceleration after motor burnout is about the most I've ever seen.

 

[HaackIt]

Yeah, it didn't have much mass to keep it moving and the Nike Smoke isn't the most graceful of airframes.

 

[HaackIt]

Here's one of the FIPa files for my L3 launch. Does anybody else have trouble with this? I can zoom in and out on the graph with older FIPa files just fine, but whenever I open the two I pulled from this launch and try to click on the graph, FIP crashes. I can get summary information, I just can't zoom in on the graph.

View attachment Level3Altimeter1.FIPa

 

[patelldp]

Data file from my Mongoose 54 last month on a 54-2550 L1000S.

View attachment Mongoose54.FIPa

 

[cvanc]

Here's one of the FIPa files for my L3 launch. Does anybody else have trouble with this? I can zoom in and out on the graph with older FIPa files just fine, but whenever I open the two I pulled from this launch and try to click on the graph, FIP crashes. I can get summary information, I just can't zoom in on the graph.

View attachment 150309

Same here! Clicking on the graph (like in trying to zoom) makes the app crash. Never saw that before...

 

[Viperfixr]

Here is the flight from my Wildman Darkstar Extreme on an AT L900DM. I am surprised at the G forces at/around the apogee event and I think my main may have come out at apogee as a result, despite using nylon 2-56 shear pins. Since the flight was beyond visual range, the data is all I have to go on, but I do not see a drop in descent rate when the main charges go off. This rocket had redundant electronics, so an RRC3 was the primary for the apogee event and the Raven primary for the main event, and vice versa for backup duty. Also, the rocket went way off vertical shortly after leaving the rail, but I cannot determine the velocity at the time of the apogee event. Any thoughts on what the data says here?

View attachment JihadThis 19 Oct L900.FIPa

 

[HaackIt]

Same here! Clicking on the graph (like in trying to zoom) makes the app crash. Never saw that before...

I'm going to try pulling the files again. Maybe something went wrong when saving those off for the first time.

 

[Adrian A]

Here's one of the FIPa files for my L3 launch. Does anybody else have trouble with this? I can zoom in and out on the graph with older FIPa files just fine, but whenever I open the two I pulled from this launch and try to click on the graph, FIP crashes. I can get summary information, I just can't zoom in on the graph.

View attachment 150309

It behaves the same for me, too.
I'll pass this along to Kevin and maybe he can figure out what's going on.

 

[Adrian A]

Also, the rocket went way off vertical shortly after leaving the rail, but I cannot determine the velocity at the time of the apogee event. Any thoughts on what the data says here?

Based on the Gs at apogee, I think you're right that the horizontal velocity at apogee, due to an off-vertical flight, was probably the problem. The descent rate from apogee looks pretty slow, and although you can see accel evidence both charges going off at the expected main deployment altitudes (and electrical status of the Raven's charge going off at the main altitude) there wasn't any noticeable change in the descent rate.

 

[kjs]

Here's one of the FIPa files for my L3 launch. Does anybody else have trouble with this? I can zoom in and out on the graph with older FIPa files just fine, but whenever I open the two I pulled from this launch and try to click on the graph, FIP crashes. I can get summary information, I just can't zoom in on the graph.

View attachment 150309

I get the same behavior so will see if I can figure out what FIP is doing this evening. A quick check confirms that it also happens in the debugger in both debug and release builds with Dev Studio not catching any exception or anything (making it harder to find/fix but should be doable). Thanks for pointing this out!

 

[Viperfixr]

Based on the Gs at apogee, I think you're right that the horizontal velocity at apogee, due to an off-vertical flight, was probably the problem. The descent rate from apogee looks pretty slow, and although you can see accel evidence both charges going off at the expected main deployment altitudes (and electrical status of the Raven's charge going off at the main altitude) there wasn't any noticeable change in the descent rate.

That's what I thought based on the zipper-ish condition of the lower airframe (did not cut through, but roughed it up a lot) and the lack of a descent rate change when the main charges went off. Plus, that 2 mile retrieve that took three hours was another indicator .

Kudos to the Wildman Recon 24" Drogue--it took the full brunt of the event on a 17lbs rocket and looks like new.