Distance from nose cone to vent hole

[rocketsonly]

Hey all. What is the recommended distance from nose cone to vent hole for an altimeter? What is the least you guys have used before? I'm using a 1.6in diameter body tube.
Thanks,
Matthew

 

[hokkyokusei]

I seem to remember "at least one caliber down from the transition from nose cone to body tune", but I can't recall where I heard it.

 

[rocketsonly]

So say on a 1.6 in tube, would 4 inches from nose cone to vent hole be fine?
-Matthew

 

[teflonrocketry1]

As per Adept Rocketry (Adept Instruments, Inc.) for their A1 altimeter at:

https://www.adeptrocketry.com/A1ds.htm

"Vent holes should be a minimum of four body diameters below the junction of the nosecone with the rocket body. This is necessary with high performance (high speed) rockets. The tremendous pressure on the nosecone leeches down the rocket body as much as four diameters before it dissipates. However, the A1 (standard and standard metric versions in particular) is not intended to be used in high performance rockets. With lower speed rockets, the "minimum of four body diameters" rule may be reduced to one or two."

Bruce S. Levison, NAR #69055