Full Scale ARCAS Rocket

[mbauer]

Getting ready to test the newest build: Full size ARCAS Sounding rocket.

Rocket is 4.5" diameter [11.43cm] and is approx. 7'9" long [19.685cm]. Before adding the parachute deployment system it weighs 10.4oz [294.835gm].

Several modifications were done to the rocket to get it to this completed stage. Looks bad but ready to test, different color ink in places due to ink cartridge replacements, rocket blew over in the slight wind we have today, grass was wet and stained the rocket, messed up on the nosecone, used tape on the glue seam to fix. Not a very pretty rocket, but should work for flight testing. Changes were made to original drawing to fix design issues found when building. Pretty sure not much of the flaws will be seen from 200ft away.

AirBlast deployment system will be the first test of using a small balloon and the altimeter electrical charge to pop the balloon. Very thin Nichrome wire hopefully will heat up at 3amps and a few milliseconds to burst the balloon.

Altimeter uses a 9volt battery and must go above 200ft [60.96m] to activate the electrical charge. Once it descends to 100ft [30.48m] the altimeter will send the electrical charge to pop the balloon.

Will this all work? One way to find out.

Will install the parachute, altimeter and solder up the nichrome wire today. Hoping for low wind tomorrow and no rain to test. Overnight glue drying time to make sure everything is nice and solid.

Photo Shows the air holes to give the altimeter a static PSI reading, also shown is the Estes BT-50 body tube internal PSI tube that hopefully will handle the 150lb air pressure, the tank will supply to "Blast" it off, This was modified to add the air holes after original print job, no need to edge color, but it was completed anyway:


Photo shows the ARCAS length and the 3/4" EMT pipe-Electrical Metal Tube (electrical conduit):


Photo shows ARCAS full scale rocket mounted on the rated 500PSI Air Tank:


Photo 269 shows close up of Air Tank and rope pulley system (can be any length to provide a mandatory, safe distance, launch pull) to activate the 1/4 Turn ball valve rated at 600PSI working PSI or 150PSI steam pressure, tank needs to be hammered into the ground to anchor it against movement when pulling the launch activation rope, it is sitting on the ground in this photo, vertical legs will work for the anchor:


Photo 272 Closeup of Air Tank, PSI gage, 4000PSI rated Schrader Fill valve, 1" to 3/4 bell reducer and screwed in EMT pipe:


Photo 273 Is the the internal Nosecone assembly. Larger holes in the nosecone are for the altimeter and 9Volt batter needed to power the deployment system. Rocket internals show the plastic straws to get the Static Air PSI to the altimeter. Note cone to direct the balloon popping AirBlast towards the nosecone:


Photo 278 closeup of both the Rocket and Nosecone to show finer details:


If this doesn't work to pop the nosecone cone off for deployment, another option is from the NASA Educators PDF on flying stomp air rockets, using a heavy washer to pop the nosecone off after it reaches Apogee and the nosecone is pointed at the ground.

Mike

[mbauer]

Been doing final steps to get the ARCAS ready to fly.

9volt battery installed, altimeter added, soldered up the nichrome wire. Company that makes the altimeter mentioned a way to test the main chute deployment, but I didn't get the parts needed to test on the ground.

Used 1/16" plywood to mount everything into the nosecone. For the battery: used regular window screening to form a pocket mount. Sewed it up using carpet thread. Window screen is then screwed onto the plywood to hold it in place.

Used a BT-50 body tube to make an electronics bay for the altimeter. It has three functions, drogue chute at Apogee, Main Chute can be set between 500ft and 100ft above the ground, an AUX function allows Air starts.

I used the Main Chute deployment. After soldering everything up, plug into the battery, and all functions beeped, lights lit and looks like my system is ready for launch.

Nichrome wire is 24 gauge, which should provide the heat needed with the 3amps available. After studying and learning about the Nichrome wire, used Nichrome 80 instead of the lower nickel grade 60. Less resistance for the 80.

Parachute online calculator said to use a 30inch chute and put a 6" spill hole in the center.

Hoping to fly this week after work, but rain and wind are forecast.

Total Ready To Fly weight is 14.8oz.

One modification is going to be a bigger parachute bay. Current one is small and everything fits, but I can't blow the balloon up to full size.

Needs at least 200ft launch height so it will activate the altimeters Main Chute function. I'm thinking maybe to use the Drogue at Apogee for the first flight, just in case the 100ft height currently set at is too low.

Daughter says she wants to watch the first flight, I asked her to use my video camera to record it. She might be able to help with the launch.

Mike