What effect if vents holes became blocked right after lift off?

Had an anomaly on a recent launch which I have been emailing back and forth with Adept.

Short version.....
Large dual deploy rocket on a j350 w 2 sets of electronics which have flown many times... Adept DDC and 22 both on key switches

Both beep out ready, rocket launches, motor blows up after 500ft chutes come out and rocket lands.

I find no sound coming from rocket at retrieval. I also find no charges fired (2 apogee and 2 main) so force of motor cato pushed chutes out.
I turn off both electronics and turn back on and both tone, and 22 beeps out previous flight altitude.

After detailed inspection and several emails with Adept, I/we are still unsure what happened.

I found that my 1" quantum tube ring around my e bay can slip with a little pushing and cover my vents holes. This happens as both key switches are side by side and this is holding the ring in place.

We know the electronics detected lift off is why they went silent.....what happened next?
Steve

Could it be the cato

How?
If lift off was detected which is indicated by both units going silent.....when the rocket stopped going upwards it should have fired the apogee charges and since main was at 600 and backup at 300, at the bare minimum the 300ft charge should have gone off since the rocket did reach 500ft or so.

We did have a very slow climb off the pad as it was a 12 ft 4" diameter rocket. One of the theories Adept suggested was the rocket never had the minimum speed/force to cause the units to arm. (we have a video that shows entire event)

I am looking for alternative theory's here or actual experiences with failures. I can understand 1 unit malfunctioning, but 2????

Steve

Steve... post the video

Related to Mach inhibit safeguards? Or maybe just that their the algorithm detects going past 600' in the downward direction. If you never get above it, the algorithm never fires? Just thinking out loud.

Could be they require a longer period of acceleration to arm. I've found that out the hard way.

I'll bet John Beans could weigh in, here. But Dick's questions are the ones to ask Adept. What series of events is required in order for the SW to register a "launch?"

Also, like you said, if the vent holes get covered, then you have no sampling of outside air, meaning that the altimeter is only sampling the same air over and over again, which means that it thinks it is sitting still.

Do you have any flight data, i.e. a graph or time/altitude dump? I think you'll probably find your answer there. The switch band sliding down over the ports probably isn't enough to cut off all of the air, the only effect would be to restrict the flow a bit. Essentially that would cause it to be sort of a pneumatic low-pass filter, which shouldn't affect deployment events since they occur at relatively low velocities.

cerving said:

Do you have any flight data, i.e. a graph or time/altitude dump? I think you'll probably find your answer there. The switch band sliding down over the ports probably isn't enough to cut off all of the air, the only effect would be to restrict the flow a bit. Essentially that would cause it to be sort of a pneumatic low-pass filter, which shouldn't affect deployment events since they occur at relatively low velocities.

Click to expand...

Agreed. I would think this would only delay deployment events by a few seconds as the pressure change is impeded but not likely fully stopped. That said, taken to an extreme, the flow could have been totally impeded I suppose.... I'll make some more spitballs.

Bat-mite said:

I'll bet John Beans could weigh in, here. But Dick's questions are the ones to ask Adept. What series of events is required in order for the SW to register a "launch?"

Also, like you said, if the vent holes get covered, then you have no sampling of outside air, meaning that the altimeter is only sampling the same air over and over again, which means that it thinks it is sitting still.

Click to expand...

This is whay adept said......................Once they detected 300 foot liftoff, they went silent and waited to detect apogee followed by main. The conditions for main ejection must occur, and then the flight is over. The ADEPT22 would start beeping out the altitude, and the DDC22 would go back to ready mode.

So if power was never lost, then both units should have fired the mains, one at 300 feet, and the other at 600 feet as you said they were set.

The units must QUICKLY reach 300 feet to detect liftoff and arm. This is a little less than one G for about 4.5 seconds. Per the video, I don't think the rocket reached 300 feet within 4.5 seconds. But it appeared to get faster as it ascended, and it would have armed shortly higher than 300 feet, and everything would still work fine.

But, but, but if the entire flight stayed slow at an average speed of less than 300 feet per 4.5 seconds, or about 67 feet per second, then I can see where some very strange things could happen with the software. Add in to that the possibility that the static ports may have been getting modified over time