Methods of putting electronics bays into nose cones.

[BsSmith]

I'm being crazy this year and putting an I59 into my Pem Tech King Kraken at Midwest Power this year. Since the I59 doesn't have an ejection charge, I have to put electronics bay in it, probably in the nose cone. Does anybody have a way of putting an E-Bay into a nose cone? Is there a way to use a barometric altimeter with it? I think I have an accelerometer based altimeter, but if I can I don't want to use it because I'm already using it in two other rockets.

 

[bob jablonski]

I don't know if PML still makes it but they had an intellicone. Cut a hole in the cone to hold a BT55 or 60 (depending on the cone and electronics) Add vent holes near the base (outside) and a mount to hold the electronics. If nose cone has a eye on the side your set or you may have to add a screw eye on the side. if its a PNC I would add a washer inside so it won't pull out as easy.
Mr. Bob
Starlight Dude
www.starlightrocketry.com

 

[DAllen]

That may not work with some baro boards. IIRC the PF HiAlt45k manual recommends that the sampling holes be 3x the body diameter away from any transitions, nose cones or fins to prevent irregular airflow over the holes. 2" body tube diameter means the sampling holes be 6" away from the base of the nose cone.

I would check the alt's manual before putting it in the nose cone. I wish there was a way around this issue because if there were a solution then that would make it a lot easier to put my baro alt in stubby rockets.

-Dave

 

[BsSmith]

The major problem with baro altimeters is the turbulence.

One way to possibly get around it is to drill the vent hole into the body tube 9" from the top and then drill the E-bay vent hole in the bottom of the nose cone. The altimeter would have to be pretty corrosion resistant that way.

 

[Adrian A]

I frequently put a Parrot altimeter into the cone. A Parrot and a Beeline transmitter will fit side-by-side into a 29mm cone, and you can have the antenna pulled straight by the shock cord.

The Parrot uses its accel for liftoff detection and an accel-based apogee detection is the default method for apogee deployment output. You can also set it up to do a baro-based apogee deployment if you want, and ignore any transients while it's going > 200 mph based on the accelerometer.

 

[Buckeye]

See this thread from the archive:

https://www.rocketryforumarchive.com/showthread.php?t=31339

I have a baro altimeter in the nose of my Minni Mag (vent holes are in the shoulder/BT, just a couple inches below the top of the BT. No problems.

 

[DaveHein]

I don't think there's a problem as long as the static ports are on the lower portion of the nosecone where the sides are parallel. You could run a test flight using a motor with a built in ejection charge first. Check the altitude data from the test flight to make sure it looks OK. If it checks out OK you could then try electronic ejection with the I59.

Dave

 

[BsSmith]

Ok, so a baro altimeter will work and deploy in a nose cone, it just won't be accurate on the way up.

So, I could use my MAWD, which is the altimeter that I'm using the least. Or, I could use my Parrot (Great altimeter!), which I'm using in two rockets. Right now, the Parrot seems like a better option, since it has an accelerometer based apogee. It will also be a better fit in the BT-60 tube I'm planning on using. I'll just fly the "higher risk" flight on the second day of the launch, and the Talon and this on the first day.

 

[ben_ullman]

Ok, so a baro altimeter will work and deploy in a nose cone, it just won't be accurate on the way up.

So, I could use my MAWD, which is the altimeter that I'm using the least. Or, I could use my Parrot (Great altimeter!), which I'm using in two rockets. Right now, the Parrot seems like a better option, since it has an accelerometer based apogee. It will also be a better fit in the BT-60 tube I'm planning on using. I'll just fly the "higher risk" flight on the second day of the launch, and the Talon and this on the first day.

sounds like a good plan to me!!

Ben

 

[Pem Tech]

Go Brian!
What kind of performance are you expecting from your King Kraken on that motor?
And pictures...
We must have pictures!

 

[Larry Curcio]

The major problem with baro altimeters is the turbulence.

One way to possibly get around it is to drill the vent hole into the body tube 9" from the top and then drill the E-bay vent hole in the bottom of the nose cone. The altimeter would have to be pretty corrosion resistant that way.

In my experience, nose cone troubles don't come from turbulence, per se. The curved shape and orientation of the nose cone make for airstreams that are unrepresentative of static pressure. Near the front, the pressure is higher. Near the back it tends to be lower.

All of that tends to make the barometric altitude time curve different from the inertial altitude-time curve. The effect is worst at high speeds. None of that affects maximum altitude much, since most rockets are traveling slowly near apogee.

Those of us who analyze inertial data in two dimensions rely on having good barometric data to verify our results. If you are interested only in deploying recovery devices, it doesn't matter - but then you likely need a real altimeter bay anyway.

 

[BsSmith]

Go Brian!
What kind of performance are you expecting from your King Kraken on that motor?
And pictures...
We must have pictures!

Thanks,

I really don't know what it will do, it could go 1000 feet or 4000 feet. I'll just fly it and see what happens. It will need more nose weight because of the heavy motor, but I'll try and put the battery as far foward as possible.

Here it is flying on an H73 (I had to crop the picture a little). It hit about 1000 feet on that flight. The negative version of that picture is my avatar.

 

[BsSmith]

Here's a picture of the finished E-bay.

It has a 1/2" plywood ring, and a bulkhead. The bulkhead screws into the ring. the sled is removable from the bulkhead, and it goeas into another rocket. When the flight doesn't need electronics, I'll just take the sled off.

No noseweight needed.

 

[Adrian A]

Looks nice. What size tube is that?

 

[BsSmith]

It's a 3" LOC nose cone. The sled fit's into an Estes BT-70

It would take some major mods to fit this design into a smaller cone, it's a tight fit through the ring.