Archive for October, 2010

Black Powder Experiment

This work for L3 project is really stretching my skillz. Since I am using electronics to control deployment of the parachute, I get to experiment with black powder, that’s gun powder people. Makes me feel like a mad scientist. With this rocket kit, it uses nylon screws to keep the nose cone in place.

As part of my design, I have to determine how much black powder is needed to properly deploy the recovery system. So I need enuff umph to break the shear pins, blast off the nose cone, and eject the parachute. I calculated some rough estimates based on the rocket diameter and tube length, however I did not know how to take into account the shear pins. G recommended a ground test.

Here’s the set-up. The rocket rests on wooden holden with lots of blankets to cushion any parts and protect G’s house from destruction. There are wires leading from the charge in the rocket, hooked up to a battery, with a continuity key/launch button. G’s done this before so has the process down, and all the right equipment to make it easy.

Here’s a video of the ground test http://www.youtube.com/watch?v=pYIZfPW9pY8

Be warned this is my first video, so excuse my lameness. The 2g of black powder was clearly not enuff. I will re-test at Plaster site with 3g.

Flight rescheduled for Nov 6th @ Plaster Blaster 2010

My original plans to launch level 3 test flight October 9th were canceled. So Plaster Blaster 2010 November 6th is my new date.

I had to travel up north to the San Francisco bay area, so I packed up my car with my rocket build. Still had some finishing touches or at least that is what I thought. My mama loved the fact that I took over her dining room with all my stuff.

There were quite a few pieces that needed epoxy. The external fillets for the fins were one of the big areas.

The fillets look pretty ugly but hey they look sturdy. Just could not get the epoxy smooth. The transition from the bottled epoxy to the West Systems has been much tougher than expected.

My attempt at installing the motor retainer gave me fits, so I decided to wait until I got home to deal with that. The urge to smash it was too great to risk it.

What Do You Mean I’m Not Supposed to Have Parts Left Over?!

%$#@!*&!! While talking electronics board with G, he noticed that a Kevlar strap that should have been epoxied to the front centering ring was sitting there in my pile of unfinished parts. Just there mocking me, as I had already built the motor mount tube with the centering rings and it was supposed to be part of this assembly.

Sigh, this is not the first nor the last dumbass move I will make. So frustrating, every day I wait for my brain to just snap back to normal but alas it eludes me. This damn medical issue makes me feel like years of heavy drug use has ravaged the majority of my brain cells. Good thing I have rocketry challenge for gray matter development. It’s forced me to learn skillz and use tools I never would have otherwise. I actually own tools and a toolbox now! 

I mentioned in a previous post that I am using a new type of epoxy. Luckily two mistakes 1) with the mixing proportions and 2) forgetting that G told me to use JB Weld to tack the fins, actually worked in my favor to counteract the not in place strap. The ratio of resin to hardener I used made a mixture with a longer curing time. So denatured alcohol softened the epoxy and I was able to disassemble with lots of effort with a knife and dowel.

Today I’ve forgiven myself for the mishaps and am back on track with the build.

Electronics Board – A Test for the Space Challenged

I love this cartoon. This portrays my rocket projects quite well. 

 

October 9th is the big day for my pre-level 3 flight on an L motor. Setting a date helps me keep the end goal in mind. 

 

This project requires an electronics board with altimeters to measure height of flight and to control the timing of the parachute deployment. Since this will have a beast of a motor, will also include a receiver for tracking the rocket location. Many good rockets never come home, so having a tracker improves the odds. I remained convinced that the animals in the huge burrows scurry out and grab random rockets.

G graciously agreed to entertain my questions and impart important details for designing a board. I even received a lesson in soldering. I find the idea and figuring out how to make all needed components fit on a board within a space quite funny. I’ve always been space challenged, and is very apparent as I try to fit everything into my car. The art of packing is just lost on me.

Pictured is my unpolished lego layout style vs. a more sophisticated Adobe Illustrator layout.

This is a close-up shot of my taped in place layout. The next day the adventure starts with locating switches, wires, metal tubing, JB Weld, U bolts, quick links and two-sided foam tape. My goal is to have the board ready to go by mid week.

Rain, Thunder and Lightning Desert Style

This weekend, I enjoyed a lil procrastination with the lure of rumored perfect launch conditions.

It was a desert first for me 1) I arrived before G 2) thunder and lightning 3) earlier rain made ‘road’ conditions out to the launch site mushy and somewhat tricky with my low rider. The weather did not bother me, as I am only happy when it rains. Was nice to have cool conditions instead of the usual blazing sun and heat.

Last drag race with G, my rocket serious lagged so I demanded a rematch. This time went much better with an even match according to the picture. Although from my viewpoint it looked like G’s launched about 2 seconds ahead. Cheshire’s paint job is in need of serious repair.

Funny incident, I thought I’d packed everything. Making a serious effort to be more organized and make a packing list. Get to site and cannot find the I445 motor we planned to race. Later at home unpacking my car, I find it under the seat. It must have escaped the bin and rolled under. 

A Fin Tale

Was so excited to have the fins in place and could start thinking ahead about the electronics board.

After several fin mishaps in the past, I used a new technique to test fit fins and then number fins/slots that fit best.

A fellow rocketeer on the rocketry forum recommended using clamps and sticks to keep the fins aligned when curing.

Making Progress

After drilling what seemed like a gazillion holes for rivets, shear pin/nylon screws, vent holes, and fin fillets, I was ready to start assembly. This is the first rocket I’ve built that uses rivets and screws to hold the nose cone and coupler in place.

So far Monty approves of the work in progress. He thinks the rocket is his, *not*.

The test fit of the centering rings went well. All that sanding was productive.

Have graduated to industrial epoxy, so no more stinkin’ squeeze bottles. The pump system is so much easier. Trying to get a handle on the proper ratio of resin to hardener with some added colloidal silica to get the appropriate viscosity.