Cool Engineering

Info on some cool engineering projects

Sunday, April 29, 2007

Alcohol Burner/Stove

In a mood for building something I thought I would try my hand at building an alcohol stove (from Pepsi cans). This was based on the design found here. Halfway though the construction I found what seems to be a much more efficient burner, but as I was already engrossed in this one I pressed on.
My construction varied - mine uses no tape, and features small pop-rivets to join the middle separator ring together.
The results in non-optimum (the pot is uncovered and is sitting too high) was that it took 50mL of Metho, approximately 8 minutes to boil 500mL of water.
The improved version seems to be much more efficient (31.9mL of Metho to boil 945mL in approximately 8 minutes) - I might build this 'penny' version next, along with a pot holder. It would seem that Americans call Metho denatured alcohol (which was proving most confusing at first as I’d never heard of denatured alcohol).

Saturday, April 28, 2007

Fix-it 1: Violin mic

Recently at church there was a little accident relating to a musician getting tangled up in the cable from a violin pickup mic. This resulted in an intermittently working pickup - due to a break in the rather thin cable running to the mic.
The fix was relatively straight forward and cost effective.
Simply getting a new length of cable ($2 worth) and a new 6.25mm mono plug ($0.85 worth). The old cable was desoldered from the pickup and the new cable soldered in - easy!

Fix-it Introduction

Being an engineer with a background in both electronics and computers ensures that I get plenty of questions from family and friends - particularly when something breaks down - (or breaks!). So I can keep a record of things I have successfully fixed, for educational reasons and also to give me some content for this journal. I hope to post a weekly fix-it instalment - this will of course depend on how often things break down - but based on experience this is not entirely unreasonable.

Thursday, April 26, 2007

Surefire is sure-bright!

About 12 months ago I purchased a Surefire 6P torch. Not only are these things about the toughest torches I have ever seen they are also exceptionally bright. This was borne out on a recent beach mission up at Halls Gap I was volunteering on.
Half way through a concert night and just before an illusion act someone tripped over a powercord - which meant we lost all sound and lights. It looked like it would take a few minutes to restore lights so I went forward with the Surefire and used it to light up the stage area - which it did exceptionally well - providing enough light to ensure the performance was easily seen.
These torches aren't cheap - mine set be back in the order of $80AUD - but for the quality and brightness they are well worth it!

The Carnage!

After several months of relative inactivity on the UAV/flying front I decided ANZAC day was the perfect day to get back into it. The weather was perfect for flying - hardly any wind, and lovely and Sunny - but not overly glary.
The original plan was to first take out the UAV and (under complete manual control) put it through its paces. I was really looking forward to this, as when we were flying with all the extra hardware onboard it was a little laid down and was really sluggish - I was really looking forward to doing a bit of aerobatics and really opening up the throttle. But those plans went amiss - it seems I completely destroyed the motor speed controller/BEC circuit in the latter stages of our project - now the BEC doesn't work at all and the motor speed controller is stuck at full throttle - a replacement module is on order from hstore.
In the mean time I managed to switch over my controller from mode 1 to mode 4 setup (the cause of at least 4 crashes).
Failing the UAV - I still had the heli which I'm trying to learn how to fly. The first flight was uneventful - hovering a foot or so off the ground - gently hovering up and down. Spurred on by this success I charged up the battery and promptly did the chopper a whole lot of damage - 5 seconds into flight. A foot of the ground the chopper banked left - the rotor clipped the ground - flowed by the tail. Total damage: tail boom snapped in half, damaged rotors, missing tail gear. I have now order the spare parts and a new (different) chopper. Hopefully this will be easier to learn to fly in.