Raven 3 in a nose cone

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

tfish

Well-Known Member
TRF Supporter
Joined
Dec 7, 2009
Messages
3,522
Reaction score
2,749
It's been about 12 years since I put an altimeter in a nose cone. I'm planning on putting a raven in the nose cone for a flight I'm working on. Is there any special programming of Raven's when used in this application? If so a screen shot or an attachment of the actual program would be useful.

My vent holes will be about one caliber below the shoulder of the nose cone.
IMG_0183.JPG

Below is how I normally program my Raven when used in a conventional electronics bay.
Mr Jaguar.jpg

Tony
 
Last edited:
I haven't flown a Raven in while.
I had one in a NC setup but, had to swap it out for a Missile Works RRC2+

The Raven setup I had was based on accell rather then baro.
When using the accell setup: that I run in my 3.0" conventional rocket; I add about a 1/2 sec of delay for apogee.

JD
 
I have done this a number of times. Just set the Raven for accel deployment. I actually don't put the sampling hole in the shoulder but instead at the bottom of the nosecone itself. Making the hole slightly oversized and gluing in (silicone bonding adhesive works well) a short section of plastic straw tilted upward helps to prevent excessive ramming/swirling of the air.
 
If you are using barometric apogee deployment, then you need to determine how the air will get to the altimeter. I normally do this with a hole at the bottom of the cone as Tim mentioned, and then holes into the airframe below the cone. The downside of this approach is that the altimeter sees the pressure spike from the deployment charge. I haven't had a problem with this, with charges generally located below the chute. A charge directly below the cone would be an issue though I think. Holes directly into the cone shoulder would require a mach lockout for any kind of extreme flight. You could do this with the timer on the Raven (setting a time "greater than" that allows the rocket to slow below transonic).

Whether you use barometric or accelerometer deployment, you need to be concerned about the accelerometer accuracy on the Ravens. Many of them measure low by about 30%. If you have one of these, you will reach V<400 too early (losing your velocity mach lockout when you might still be above mach on some flights) and V<0 too early (getting early apogee deployment). The easiest way to determine if you have one of these Ravens is to look at the acceleration on a flight with a commercial motor (where you have a simulation you can compare against). If you have one of the low-reading Ravens, it will be obvious. You can still use these, but you have to consider how to work around the issue (always flight specific).

Why is your deployment altitude so high? Planning to land on a mountain?

Jim
 
If you are using barometric apogee deployment, then you need to determine how the air will get to the altimeter. I normally do this with a hole at the bottom of the cone as Tim mentioned, and then holes into the airframe below the cone. The downside of this approach is that the altimeter sees the pressure spike from the deployment charge.

Sorry for my confusing post, when I said bottom, I meant the aft end of the exposed part of the nosecone, just above the BT/NC seam. Even with Mach+ flights, I haven't had problems here (with proper lockout of course).
 
Regarding venting the altimeter to the payload bay, if you're doing the deployment with the altimeter it might not see the deployment pressure spike, since that's of its own doing and the reading would have been taken before it triggered the charge. It depends on how long the pressure spike lasts.

Do you have it doing a drogue too? If so, how do you have that set up?
 
I believe its about 2".
Usually I split the difference and it's a 4" dia rocket.
I used 1 x 1/4" hole or there abouts.
I also used it in conjunction with a cable cutter....
I don't have access to it; it's in storage at the moment.


JD


JD, On your RRC2+ how far below the nose cone shoulder are your vent holes?

Tony
 
I got the Raven mounted on the nose cone. Then learned about how some of the power perch's had needed to be turned on and off with a specific polarity of the magnet. I thought I had it figured out until it started acting up again. I've not flown Ravens much and so the "acting up" could be me not knowing how to use it properly. So I removed the Raven and installed a RRC3 in it's place. I could not find " Missile works products work great when used inside nose cones" any where in the instructions. But I was assured that it would work just fine.
I ended up with 3 - 1/8" vent holes that were 1.4" below the shoulder of the nose cone. I was able to test fly the nose cone yesterday. It flew to just under 4K and all went well. I need to work out a better mounting method for the 9v battery.

Tony
 
Back
Top