Apogee vs Nose Over Deployment

[JBoyson]

I ran into a fun issue with a rocket flight recently where I had an altimeter that did nose over deploy not Apogee deploy. I ended up having Nose over and Apogee +1sec happen nearly simultaneously.
I made a short video about running into this issue and would love more options and just wanted to make others aware you could run into this issue.
So far eggtimer altimeters are the only ones I've found that use nose over deploy.

 

[bad_idea]

What was the nose-over altimeter?

 

[Titan II]

What was the nose-over altimeter?

"....the Eggtimer fires the drogue parachute at Nose-Over, which we define as one second past apogee (highest recorded altitude)."

Their rationale is on pages 31-32.....

https://eggtimerrocketry.com/wp-content/uploads/2018/06/Eggtimer_1_52_RevD_Manual.pdf

Exception?

"The Apogee deploys your parachute at apogee..."

 

[JBoyson]

What was the nose-over altimeter?

It's any Eggtimer altimeter.

 

[JBoyson]

I'll go find some video from my last flight and post it here. So others can see what simultaneous ejection charges look like .

While it is explained in the manual, some people will skip reading it in depth (me included) and I feel like it needs to be talked about more before others repeat my mistakes of firing both primary and redundant charges on my drouge simultaneously.

Fly Safe,

 

[Handeman]

I think this goes back to the argument about using the same model altimeters in a dual altimeter system vs. using different brands.

If they are the same brand, and you set one at apogee deploy and one at +1, it doesn't really matter since they are both going to be apogee, or nose over deploy and the one second difference should be good.

If you use two different brand altimeters, you avoid the same "bug" in the firmware causing the same failure in each of them, but you can definitely run into a nose over altimeter and an apogee altimeter both setting off the charges at the same time. At the same time, if apogee deploy is the primary, and a nose over is set to +1 or 2, you could actually end up with a 2 - 3 second difference between when the charges go off.

Since the current available altimeters have such a long history of firmware development, the bugs are almost none existent, I would disagree with using different brands of altimeters and feel that using the same brand where you can set one at 0 and one at +1, should be very dependable and ensure a one second difference between each altimeter when they fire the drogue charge.