Mike's Flying

26 sayings that indicate the ideal, synergystic working relationship:

1. I can see your point, but I still think you’re full of crap.
2. I have plenty of talent and vision. I just don’t care.
3. How about “never”? Is “never” good for you?
4. It sounds like English, but I can’t understand a word you’re saying.
5. I see you’ve set aside this special time to humiliate yourself in public.
6. My toys! My toys! I can’t do this job without my toys!
7. You are validating my inherent mistrust of strangers.
8. I’m already visualizing the duct tape over your mouth.
9. The fact that no one understands you doesn’t mean you’re an artist.
10. Someday, we’ll look back on this, laugh nervously and change the subject.
11. I will always cherish the initial misconceptions I had about you.
12. I don’t know what your problem is, but I’ll bet it’s hard to pronounce.
13. Any connection between your reality and mine is purely coincidental.
14. I like you. You remind me of when I was young and stupid.
15. What am I? Flypaper for freaks!?
16. I’m not being rude. You’re just insignificant.
17. Thank you. We’re all refreshed and challenged by your unique point of view.
18. It’s a thankless job, but I’ve got a lot of Karma to burn off.
19. Yes, I am an agent of Satan, but my duties are largely ceremonial.
20. No, my powers can only be used for good.
21. I’m really easy to get along with once people learn to worship me.
22. You sound reasonable……time to up my medication.
23. I’ll try being nicer if you’ll try being smarter.
24. I’m out of my mind, but feel free to leave a message.
25. I don’t work here. I’m a consultant.
26. Who me? I just wander from room to room.

And now Useful Expressions for those High Stressdays

1. I’m not tense, just terribly, terribly alert.
2. Not the brightest crayon in the box now, are we?
3. Do I look like a fucking people person?
4. This isn’t an office. It’s Hell with fluorescent lighting.
5. I pretend to work. They pretend to pay me.
6. You! Off my planet!!
7. Practice random acts of intelligence & senseless acts of self-control.
8. I like cats too. Let’s exchange recipes.
9. Did the aliens forget to remove your anal probe?
10. And your crybaby whiny-assed opinion would be…?
11. How many times do I have to flush before you go away?
12. Aw, did I step on your poor little bitty ego ?
13. How do I set a laser printer to stun?
14. When I want your opinion, I’ll give it to you.
15. Earth is full, Go home.

Well, in an effort to aid my revision for rapidly approaching JAR exams I’ve decided to attempt another technical post, especially seeing as my rough attempt at explaining SALR and DALR (HERE) seems to be popular with good old search engine traffic.

This week I will mostly be discussing Logic gates.

I’m going to skip the construction of these little computing wonders, though for interested parties they’re constructed out of anything from levers and weights through to MOSFET’s (Metal Oxide Semiconductor Feild Effect Transistors) on intergrated circuits such at the processor in the very computer you’re reading this on.

The great god of Wikipedia tells us that the first properly functioning Logic gates were to be found on Charles Babbage‘s Analytical engine. These were actually fairly complex constructions of pegs, barells, levers and all manner of mechanical trickery. Though the basic principles of operation from these gates to modern-day electronic gates is identical. It’s this principle I intend to explain and explore. I’m going to stick to purely electrical logic gates

I’m going to skip the lesson in the Binary (base-2) system and simply summise that as far as we’re concerned if a wire has a potential difference accross it then it’s Logic (Binary) 1, and if it has none it’s Logic (Binary) 0.

I suppose I’m also assuming that we know what a potential difference is, but for the purposes of this article we can define it thus:

If a wire has a potential difference accross it then when it is added into a complete circuit, electrical current will flow in the wire

So, our logic gates look at a selection of wires and (based on their state as on/off  – 1/0) create a logical output of 1 or 0.

There are several types of Logic gate which, surprisingly, perform several types of comparason.

Firstly, I’ll introduce the OR gate.

An 'OR' gate

Named because it will return a ’1′ if any one of it’s inputs are ’1′.  So if either the top OR the bottom input is 1 it will output 1 as well. If both are 1 it will output 1 but if both are 0 it will output 0.

The AND gate is next, again it’s function is quite simple.

An AND gate

It’ll only return ’1′ if all it’s inputs are also 1. So if the top AND bottom inputs are 1, it will output 1. If not it will output 0.

Next we’ll introduce the NOT operator. This little fellow inverts the logic on a wire. For example, if an input is a ’1′ a NOT operator will make it a ’0′ and vice-versa.

The little circle is the 'NOT' operator

So, using this NOT operator we can invert the output of our AND gate giving us a Not-AND gate or NAND gate.

A NAND gate

A simple way of thinking of this is just to treat is as an AND gate and then reverse the output you get. This will only return ’0′ when all of the inputs are ’1′.

A it follows that you can add the NOT operator to an OR gate as well, making a Not-OR (NOR) gate.

a NOR gate

There’s one other family of gates we need to know about, and that’s either-or gates. They’re basically OR gates but they won’t return ’1′ when both inputs are ’1′. You can get both a XOR gate and a XNOR gate.

An XNOR gate

An XOR gate

Ok, so that’s all our gates. Nice and simple. Next post I’ll go into where they’re used and run through some examples of simple logic circuits. Even some tricks we can pull with the gates to make them store data for us.

Since everyone else is doing it at the moment, I thought I might as well join in with a bit of snow-worship. I can only remember two occasions during my time at Cambridge where there has been significant snow (I have particularly vivid memories of rushing to  a supervision at Trinity, and then having to dash about from icy court to court, dodging snowballs and trying to find where on earth J staircase was, needless to say I was late). Anyway, cambridge has been convered with snow for a solid week, or at least most of the college lawns have stayed more or less white, and I am glad to say that there is supposed to be more on the way. A woebegone lump of snow, that was once a snowman, sits disconsolately in the middle of every sizeable lawn, and facebook is awash with blurred pictures of bulkily wrapped and be-hatted students in the act of throwing snowballs or posing in front of the aforementioned snowmen. It is all very jolly really, afterall, no one lives more than a short walk or cycle ride away from their lecture halls, libraries or departments, so all that doom and gloom disruption that we have been hearing about on the radio doesn’t apply.

Clough Hall, Newnham, which is where I live

Mark5

Originally uploaded by Mikebert4

Now we’re getting somwhere.

This fellow did fly, and fly well. We managed to coax glide ratios of 4:1 out of it (just) and it coped with quite serious changes in wind speed/direction almost effortlessly.

If you look closely, you might well notice that it’s pretty similar to Mark4 in it’s fuselage and tail. Indeed, tis the same aircraft, only with the insane-dihedral cut down to a more acceptable 5cm or so. and longer wings added.

I apologise for the sorry state of the craft in the photos, I made the mistake of flying Mark5 before I photographed it. The nature of the construction means that after a few launches (maybe 20 or so) the joints and bends become very weak and the performance suffers. It’s somthing I’m trying to address in Mark6.

Flight of the Mark5

In fact, I’ve now brought you up to date on these here model gliders, and Mark6 is still under development, with the initial test-flights looking very promising.

The Techy Bit:

The only thing I will point out on Mark5 is somthing called gurney flaps. The trailing edge of the wing is folded down at 90º to the airflow and extending about 5mm below the wing. This increases drag (which is bad, but on a model this size, going this slow the additional drag is actually trivial), but it also increases lift. Simply put, it traps air under the wing a little bit, causing a higher pressure and hence more lift.

Mark4

Originally uploaded by Mikebert4

Ahh, Mark4.

Good idea, bad implementation. Glided exactly as one would expect from a brick suffering vertigo. The wings suceeded in making the glider (pah!) wallow on it’s little-slowed descent.

Mark 4 during construction

Seriously though, the idea of including an insane-dihedral to secure stability, and then straight wings to produce the lift was a good one. I just over-did the dihedralto the point where the whole middle section is producing no lift at all, and a lot of drag. Plus the little straight wings had a habit of folding up and aiding the inevitable plumet earthwards.

On the plus side, it was incredibly stable.

I’m not even going to go into the technical side of this fellows failings.