What happened?

[wfcook]

What did the rocket weight, and which K650 were you using? What was your actual predicted altitude?

At what altitude did you expect to go through Mach 1, and how close is that to the estimated failure point?

Do I understand correctly that your static ports are on the same side of the rocket, above and below the switch? I should think that could make the av-bay susceptible to self-sustaining pressure oscillations, especially in a regime of compressible flow. I should think three evenly-spaced holes would be safer.

 

[Bat-mite]

I believe the RRC2+ can be mounted/oriented in any direction, as for the vent holes, I've always seen no less than 3 evenly spaced around the body tube/switch band and usually 3/16" each.

From the Users Manual:

The RRC2+ can be mounted in any direction on the sled.

Check.

The RRC2+ should be mounted above the sled a minimum of 1/8" on standoffs or insulated washers. The barometric sensor mounted on the bottom of the altimeter has tiny holes in it to sample air. They must NOT be blocked by mounting too tight on the sled. If you can slip a credit card between the bottom of the RRC2+ and sled, you’re good to go!

Check.

Vent holes in avionics bay allow the altimeter to sample air pressure. Here are typical some 3-hole example sizes:
A. 38 mm by 6 in. 3 x 1/16” holes
B. 54 mm by 7 in. 3 x 1/8" holes
C. 3 in. by 9 in. 3 x 5/32” holes
D. 4 in. by 12 in. 3 x 3/16” holes
E. 6 in. by 18 in. 3 x 1/4"holes

Crap. Mine is D.

Looks like that was my mistake, guys. I have the manual, and even read that part, but when it got down to the building, I think I just lost my mind. Or maybe I meant to go back and add them but then it got lost in the rush.

Well, live and learn. I won't be making that mistake again.

Thanks to all who've helped.