Nike Nosecone Electronics Version 2.0

[COrocket]

I had to rebuild my avionics board for my 1/4 scale Nike Smoke, and I tried to tweak/improve the board from the original design (Original avionics photos at https://www.rocketryforum.com/showthread.php?24028-Electronics-in-Nike-Nosecone)

Some highlights are:

1. The 9V batteries were replaced with Turnigy 370mAh Li-Po batteries https://tinyurl.com/9mf86px They are secured using screwed down strips of 1/16" thick aluminum angle at either end of the battery. The batteries are also held in place by a nylon strap.

2. Strattologgers replaced the RRC2-mini's

3. Stainless L brackets replaced the nylon spacers that were glued to the board. The board connects to the brackets using socket cap screws.

4. Wires on the backside are secured to the board using wire staples (credit GaryT for the idea). They help keep everything tidy and organized. The wires disconnect from the bulkhead using JST connections, which are the same as the battery. I choose them so that if I ever had to replace a wire, I only needed to carry spare JST pigtails.

 

[COrocket]

Also what the Strattologger allowed me to do is look at the baro data from the flights. With the RRC2's, I just knew that it "worked" and would report a reasonable max altitude. There was some question as to whether putting the vent holes immediately below the nosecone transition would interfere with the pressure readings. From the raw baro graph it looks like it works just fine. Motor ejection was used for that flight which is why the airframe didn't separate exactly at apogee.

 

[cwbullet]

Very nice design. Thanks for sharing. Can you post a pic of the other side the bulk head?

 

[COrocket]

Here it is installed in the nosecone. The recovery system pops the nosecone at apogee and the tether releases the parachute (which is wrapped in a nomex chute protector) at the main altitude.

 

[Brent]

How do you arm the altimeters? Never mind now I see the switches.

 

[cwbullet]

Pretty impressive. I have a V2 to build in the future and will need a similar set up.

 

[cerving]

Where do you put the pressure vent holes for the Stratologger? I assume the bottom of the nose cone vents into the body tube. Since the Nike Smoke's nose cone bulges out larger than the body tube diameter, there will be a pretty significant pressure differential between ambient pressure and the pressure 1-2C behind the nose cone.

 

[COrocket]

Where do you put the pressure vent holes for the Stratologger? I assume the bottom of the nose cone vents into the body tube. Since the Nike Smoke's nose cone bulges out larger than the body tube diameter, there will be a pretty significant pressure differential between ambient pressure and the pressure 1-2C behind the nose cone.

The vent holes are near the top of the body tube as seen in this picture. The nose cone does not vent into the body tube, to protect the altimeters from the ejection charge pressure spike. I thought the vent hole location might cause problems so for the first flight with the altimeters they were only along for the ride. After looking at the data the effect doesn't seem to be significant enough to cause a noticeable pressure drop, which would trigger the apogee event. As the rocket slows nearing apogee the low pressure region would diminish, allowing for an accurate apogee measurement.

 

[cerving]

I assume the vent holes go through the shoulder of the nose cone... otherwise there wouldn't be any way for the pressure sensor to pick up the outside pressure.

What is your expected maximum velocity? It would be interesting to see the graph from the Stratologger, if you're expecting to hit Mach .7+ you'd expect to see a pressure rise but the location of the holes may actually cause the perceived pressure to drop in relation to the nose cone's pressure.

The vent holes are near the top of the body tube as seen in this picture. The nose cone does not vent into the body tube, to protect the altimeters from the ejection charge pressure spike. I thought the vent hole location might cause problems so for the first flight with the altimeters they were only along for the ride. After looking at the data the effect doesn't seem to be significant enough to cause a noticeable pressure drop, which would trigger the apogee event. As the rocket slows nearing apogee the low pressure region would diminish, allowing for an accurate apogee measurement.


View attachment 102653

 

[patelldp]

It seems like drilling independent holes for each wire could cause for a greater chance of leakage into the nosecone electronics bay. While this is nice for organizing wires, you run a higher risk of leaks. Have you sealed these holes with something like hot glue?

This looks really good, I like how clean the electronics bay is.

 

[COrocket]

I assume the vent holes go through the shoulder of the nose cone... otherwise there wouldn't be any way for the pressure sensor to pick up the outside pressure.

What is your expected maximum velocity? It would be interesting to see the graph from the Stratologger, if you're expecting to hit Mach .7+ you'd expect to see a pressure rise but the location of the holes may actually cause the perceived pressure to drop in relation to the nose cone's pressure.

Yeah the vent holes go through the nosecone shoulder. I've only flown it up to about mach 0.5, because we have a relatively small field to launch at. I hope to take it out west and launch it on a large K motor some day, that would probably get it there. That may test the stratologgers "mach lock" feature if it picks up anything strange.