Hello Champkai32,
I would like to first echo post #11 from Mike in NE Ohio. Put the pressure equalization ports thru the bottom of the nose cone into the airframe itself. If you put the pressure equalization ports anywhere on the surface of the nose cone you will end up with absolutely false readings. The pressure on the surface of the nose cone, and there fore thru any ports thru the nosecone, is going to be greater than anywhere else on the rocket simply because it is the surface which is pushing the air aside. Any readings you get from ports thru the NC are going to be false readings. And even if you only go just past ******, it will spell disaster for any kind of barometric deployment electronics. Mach-2 plus is taking you thru a "whole 'nother critter."
Placement of the ports on the airframe itself is also important. In order to get clean readings without any false pressure spikes, you need at least three ports spaced evenly around the airframe. The old rule of thumb as I was taught it was a minimum of a full caliber behind and in front of the closest gaps in the airframe. In this case that gap would be between the nosecone and the airframe. This rule was very effective for rockets flying under ******. But you are planning on going a whole lot faster than merely breaking ******.
Going mach means that you are going to go thru the transonic region that is the transition between below mach speed and greater than mach speed. Funny things happen with pressure on the surface of an airframe traveling thru the transonic region. At least one very sizeable pressure wave will actually travel over the surface of the airframe from front to back as the rocket goes from below mach to above mach speeds. And depending on your design, there may be more than one pressure wave traveling back and forth along the airframe at the same time. Think along the lines of Chuck Yeager breaking the sound barrier for the first time. In his own words the airplane seemed to loose control during what we now know was the transonic region, but that control was reestablished once the airplane broke thru into the mach+ region of speed. There is a great deal of violent turbulence in the transonic region and it is not very easy to predict what it will do to your rocket.
Then you need to think about what kind of electronics you are going to be using. Not all of them are capable of working properly thru the transonic region and into multiple mach speeds. In the earlier days of electronics a whole bunch of them failed because they were not designed for mach speeds. Most of them these days, use a kind of false reading inhibitor to keep from reading these false pressure wave spikes as apogee and trying to deploy the recovery system, usually at Max-q which is always disastrous, at least in my experience.
There are other things that one can do, but please be careful. Going mach 2 plus can be a very challenging thing to attempt. I was in one of Tim the Wildman Lehr's N-10000 drag races out at LDRS 29 with 6" diameter Wildman kits on the 98mm Cessaroni N10,000 motor. I only have data for my rocket which hit mach 2.6 going straight up. I was not the first off the pad, but I did hit 14881 feet which was the highest recorded altitude of the group. Check it out on youtube at "wildman's N10,000 drag race" or cut and paste the following into youtube. For whatever reason I'm having a hard time getting the link to appear all I can get is the text.
So I speak with some experience. It can be done, but it is a challenge. And if you don't do it right.....? Well, be prepared for the consequences. And honestly, if you've just got three Estes rocket flights in your experience portfolio, you are no where near ready for ****** let alone any further. I wouldn't want to be on the same field with you making an attempt right now.
Brad, the "Rocket Rev.," Wilson