Friday 27th July saw the now annual display at Drumlough take place. This has become a regular event on the club calendar and is a favourite for anyone who has been there either as a pilot or to lend a hand, not least for the offer of a steak to round the evening off!

As always it was a relaxed display, since there is music and dancing across at the hall, there is no commentary from us, so the main focus of the evening is Toffee drops  interspersed with display flights, all of which is well appreciated by the crowd in attendance.

Gerald’s video below captures the mood well, and judging by the invitation to come back next year we did our job well.

Thanks to the folks at Drumlough for their hospitality, and to the boys who went home before the food, don’t worry, we found a good home for it!!

We keep planes & helis in the air all evening and run several flights with the buddy box to let people have a go. Paul’s Easipzee & my Apprentice trainer providing the perfect buddy system, ably assisted & instructed by Dennis & Sean. Dennis had his Wot4 toffee bomber in the air as well, the young kids & not so young ones (David) enjoyed the charge for the sweets!!

It was a great evening and very well received by the Neighbours in particular!

Some pics below, I’m sure more will appear soon!

Matthew

Climb & Glide
Climb at full throttle for 20 seconds then cut the engine or motor and glide for as long as possible, with a 10% bonus for landing back on the strip. With Richard up first, getting lots of height and managing an impressive 6 minutes and 29 second glide, I think he managed to find the odd thermal. Missing the strip when landing there was no bonus for Richard. All the other pilots managed to get the bonus, but couldn’t come close to Richards time. This was a nun eventful round with no wild cards being used during this round.

Triple Thrash
Complete 3 touch and goes, 3 loops and three rolls and a final touch and go as quick as possible. Brian first up for this one getting 33 seconds. Matthew managed to beat this and done it in 20 seconds. Sean and Phelim decided their times were not up to scratch and played their wild card. Sean improved his time from 50 seconds to 35 seconds and Phelim improved his from 80 seconds to 75 seconds. Paul had a bad round, pulling the bulkhead out of the fuselage. This eliminated him from the rest of the competition.

Touch & Go
Touch and go on the strip as many times as possible in two minutes. Dennis was up first and set the target at 11. Matthew got the most in this round with 33 touches in two minutes. Even though the pit crew were on standby for the ic models they were not needed and no wild cards were used during this round.

Limbo
Do as many passes under the limbo in 2 minutes without breaking the string. Alistair went first for this round setting the target at 14. Matthew cut the string after 12 passes and with 1 minute remaining. He decided to use his wildcard and only managed 5 passes before breaking the string again, but that is the chance you take when using your wild card.

Mystery Round
Do one fast pass into the wind as quickly as possible between the 2 markers, then do one slow pass downwind as slowly as possible between the 2 markers, nose to point in direction of travel for both passes. Score is the difference between the two times, with the biggest difference winning. With the windy conditions there was not much difference between the two times. Brian got the longest difference of 7 seconds this was after using his wildcard as the model was actually flying sideways during his first slow pass, disqualifying his first time.
Positions after the five rounds are below as is the results table showing the complete results for each pilot.

1. Brian McCartan Jnr
2. Matthew Poots
3. Sean Scullion
4. Richard McNeill
5. Alistair Henry
6. Dennis McNeill
7. Phelim Lundy
8. Paul Harrison

Sean
BAC Competition Director

Alistair & myself decided to have a look at a site outside Newry recommended by our good friend from Dungannon, Richard Boyd. The site, at the Flagstaff  Transmitter is spectacular to say the least, with slopes to suit most wind directions, and best of all, a road to the very top, so there are no excuses for anyone!

Dave Nolan came up for a look, because believe it or not he fancies becoming a Glider Guider! I want to be there for his first Tic Toc!

Anyway two of us doesn’t really make for a competition, so we just made the most of a good strong breeze (understatement!) and a dry day to have a bit of craic.

Alistairs Phase6 with a good view of Dundalk.

Spectacular scenery, great views of North & South.

Pair of Phase6’s ready for action.

Looks like we’re just short of a horse and a motorbike!

Like i said, spectacular scenery, where else would you see wooly hats like these!

£5 to anyone who can spot Alistair in this pic!  (25 June: Has Alistair been found yet??)

Carlingford lough from a great height, without breaking sweat.

After the first flight with the Jeti. It feels like a totally different plane.

Most of it anyway. Still lots of details to sort out, but hey, this looks better then it did the last few weeks. One good thing about a crash is, that you get to throw away an amazing amount of garbage. Every edit or modification ever made is stored, and hence the backups grow and grow. So, right now, I have only half the data, and 90% of the stories! That’s not bad for a cold Sunday afternoon.

There are of course links to sites that haven’t been revived yet. Don’t worry, I’ll find and fix them.

 Area Funfly

The Area Funfly took place on Saturday 22^nd June, hosted and run by Banbridge Aeromodelling Club. As it turns out all the competitors were from Banbridge too, with the only visitor being Robert McElroy from the Craigavon club.

Conditions were challenging, with a fairly strong, lumpy, gusty wind which caught a few people out over the course of the competition.

The first round as always was the Climb & Glide, 20 second engine run, engine cut and glide for as long as possible, with a 10% bonus for getting back to the strip. As can be seen from the scores, this was not a round to be writing home about. The wind played a large part in this, with there almost seeming to be a downdraft over the field, all pilots did well to get back to the strip to get the bonus all be it that a couple of undercarriages were well bent on arrival.

Take off, wings level & gain sufficient height before banking gently into the turn. Or Not!!

Repairs complete, Triple Thrash was next. Three touch & go’s, three rolls, three loops and a final touch to stop the clock. Times on this were slightly better, although the wind played a part with a couple of cartwheel arrivals including Alistair who had repaired his undercarriage after the first round and now had a dinged wing! Also some of the inadequacies of earlier repairs were shown up when a slipped undercarriage leg pinned Iain’s throttle wide open, leading to a first time of just over 4 minutes i.e circling until the fuel ran out! A wildcard was used and that time reduced to 53 seconds although a gust on final approach flipped the model and broke the engine mount, hence no further scores for Iain.

Brian McCartan, flexing his knees to encourage the model up!

Touch & Go’s proved less eventful with the main problem being getting the models down in the wind. Matthew showed the looping technique off to good effect although was blown around a bit, while others chose the more traditional circuit & bump approach, Alistair having replaced his original Limbo Dancer with his optimistically packed backup! Electric models proved their advantage in this round with some arrivals which would traditionally have seen the pit crew belting out for a re-start, simply opened the throttle and continued on their way.

Matthew just under the Limbo & turning for the next 1 of 24 in 2 minutes.

The final round as always was the limbo and again the wind caused some bumpy approaches and a few cuts of the limbo string to end rounds early.

Overall it was a good days flying in challenging conditions and the best pilot won. Again it was disappointing that no other clubs took part, although the weather forecast may have put some off.

Competitors in the 2013 Area Funfly with Club Chairman Paul Harrisson.

The top Three being presented with their Certificates & The shield goes back to Matthew’s Mantlepiece.

You can watch part of Matthews Limbo Here

To say it was a busy week at the club would be somewhat of an understatement. Normally we struggle to run competitions when they are supposed to because of weather or folks being unavailable, last week, we made up for lost time, with a new format heli competition on Thursday evening, the Area Funfly on Saturday with a short informal e-soaring competition afterwards. And just to round off the week , the first round  of the Area Aerobatics/ IMAC Norn Irn competition took place on Sunday at the Tyrone Model Flying Association’s site outside Omagh.

The Heli competition differed from the normal rounds of hovering manoeuvres and basic aerobatics to a more Funfly type schedule, with three rounds flown. The first was based on the Triple Thrash Funfly round, with competitors taking off performing 2 pirouettes, 2 flips & 2 stationary rolls in the quickest time possible. Times were actually pretty tight, with the smaller 450 machines getting away with lower altitudes. Alistair also had a low altitude moment when he forgot to flip the idle up switch to give him negative pitch, resulting in his first flip turning into a very low diving manoeuvre which he did well to recover from.

On the approach to a water bottle with the 450XThe second round saw the Bamboo poles usually only seen during the Limbo at Funfly competitions being produced from the hut, which raised both eyebrows & cold sweats! Three poles were placed down the runway with enough space to fly between, and the pilots asked to fly a slalom course between the poles and back to land as quickly as possible. The presence of a physical object obviously makes folks a little more cautious with their whirling blades and with this in mind Dave  took off, flipped inverted and flew the course in a rather interesting manner with some flips and piros thrown in for good measure, and he still had the fastest time! The others followed and some oohs! And aahhs! Were produced as blade tips got close to bamboo in some overcooked turns.

Mission Accomplished!

The last round saw one pole left up and three water bottles set out on the strip, with the pilots required to knock the bottles over, hopefully with the skids! And fly around the pole before returning for each of the remaining bottles. This proved a very challenging round, with some people’s depth perception being put seriously to the test! Brian overcame this by following the heli around the strip, which incurred a 10 minute penalty for leaving the pilot’s box (judge’s decision final!) There were a few near misses as tail rotors got close to bottles, but thankfully nothing hit, at least until Matthew, flying Brian’s Blade 450X, connected the main rotor with a bottle top, resulting in a spray of water and some unrepeatable exclamations from the onlookers. Thankfully the heli survived unscathed and only slightly moist, much like the pilot!

The alternative use for a helicopter as a bottle opener!

Overall the pilots and spectators enjoyed the new format and I think this will be used at future club heli competitions. The rounds were challenging for everyone and showed pilots were in full control while under a little bit of pressure, but the overall feeling was just of a great evenings craic, much like our normal Funfly competitions.

Sounds like the title of a detective story, as a matter of fact, this story is a search for something missing. Before jumping to conclusions, we have to be clear about the word missing. There is a possibility of something being really absent, but it might be equally true that we simply percieve something to be absent, when in fact it is not. It all depends on the method of observing. And that brings us straight to the core of the problem.

If we decide we want to know the value of something, we usually have a gadget to measure that something. (Bless the 21st century)

To be more precise, when one wants to measure voltages, one uses a gadget called a Voltmeter.

When measuring Amperes (Amps in newspeak) one uses an Ampere meter.  And to join this duo, we might as well introduce the 3rd illustrious cousin: the Ohm.

And since they all depend on each other, and are often used together, some smart kid decided long ago, that it would be a neat idea to stick gadgets to measure those three friends in a single box. (I’m simplifying, hope you will understand that!)

Fast froward to the digital age, and we figured out a way to get rid of that Meter-thingy ( The nice big box with the moving needle) and replace it with something ‘digital’, a chip. And so the DVM was born. (Digital Volt Meter) .

But first, lets talk about the Volts and Amps and Ohms a bit.

It all started because some bloke in ancient Mesopotanie decided to put some bits of metal in a jar (http://en.wikipedia.org/wiki/Baghdad_Battery) and call that a battery. We still are not 100% sure wheather they actually used these batteries to fly their model airplanes, but judging by the hieroglyphics discoverd, one would not be too surprised if they if fact did. But that’s another story.

 So the fellow (lets call him Ahmed, because he likely had a name, and it could well have been Ahmed), Ahmed then, was wondering how strong the juice was that his batteries produced. The tongue test was ok, but when you put 20 jars in series, this test resulted in some strange effects: his wife was unable to talk for days or weeks, depending on the amount of jars used for the test. (Yes, dear reader, of course Ahmed asked his wife to be the tester, since she had a far better ‘feel’ for these things.) Needless to say, eventually the misses decided she had enough of Ahmed’s bat-ter-eeeeh tests, and left him for a rich merchant. Ahmed being the inventive soul, decided that something more reliable was needed to measure the properties of the the jar-juice.

He had by now worked out that there were actually 2 main properties involved with his juice-jars. The one that determined how long the missus would be quiet, he called Voltage (this word has of course been translated from ancient Mesopotania-speak for the benefit of you, dear reader), and the one that decided how many of her sisters would be knocked out at the same time he called Amperes. History has not quite revealed what Ahmed discovered, but we can be sure of the results!

Skip forward a few centuries…

Since we live in a different country, and don’t have too many volunteering wifes/girlfriends available for our tests, we have to invent a different way of testing and explaining the Volts and Amps.

Imagine my surpise, when I discovered that we have such examples right here, in the Mourne Mountains. As I was travelling through said mountains the other day, I was observing the melting snow (in April!) and the little waterfalls that the melting snow created.

Eureka, the perfect example!  The amount of water flowing down is equivalent to the Amps, and the speed of the flow is determined by the height difference between the location of the melting snow and the final destination. So if you have loads of water (Amps), and a very small height difference (Volts) you can see there will be a relatively low current. (No need to translate that). Then take the same amount of snow, and put it on top of the hill and the water rushes down, because the Voltage is now much higher. On the way down the water encounters Resistance (Ohms) in various forms. See, it’s all easy!

The moral of this story is that there is a relation between Volts and Amperes and Ohms.

Ohms = Volts divided by Amps.

Amps times Ohms = Volts and

Volts divided by Ohms = Amps.

If you think about it for a bit, it will make sense! Just replace the Amps with amount of water, the Volts is the height the water is falling, and the Ohms the obstacles the water encounters on it’s way. You will never be confused about the Volts and Amps again!

However, we are still none the wiser about How Much any of these things is. Big, bigger, loads, tiny bit??

Luckily, beeing a pint loving nation, we soon have that sussed. We all are aware of the extreme importance of getting a pint that is the same, no matter which pub serves you this heavenly brew. To make sure we all had the same pint we invented the pint glass. (No use having the pint without the glass,  right?) So now we had a pint glass and went about making sure the landlords served the right amount of fluid to each of us punters. Great. We are happy. One universal pint, no quibbles. Until…

The owner of the glassworks decided that it would be cheaper to have someone else make the pint-glasses. He simply asked them ‘send me a load of pint-glasses’. And you will already have figured out, that things from far-away-places are usually different from what you make yourself. Some time after the new pint-glasses were sent to the happy customers, trouble started. Landlords were accused of ‘you served me short’. The opposite cry was probably never uttered. But honesty requires we mention te possibility that someone cried ‘you served me long’. (Of course this language was never actually used, however since this is a nice story, I can not quote the actual words used).

This was a nuisance of major proportions. But the clever blokes we are, we soon got around that one by inventing the %, which simply is a shorthand way of saying: my pint is the same as yours. (The two little circles are symbolic pints, I don’t need to explain.)

That was all great, but what if my pint was smaller then his? mmmm…. Some pints later, after mulling over this problem, (in fact, rumour has it, that it was 100 pints later) it was decided that it would be a good idea to say that if two pints contained exactly the same amount of beer, (lets skip the method of measuring ‘exactly’, since that involves even more beer) we would say they were 100% the same!

Hah! now we’re drinking. And a whole new mathemathics was born, jobs were created, life was good. And kids soon figured out it was a lot easier to ask their parents for a 50% pint. All they had to do was ask twice, to get the same amount..

Due to the enormous amount of pint-glasses around, it soon became a bit impractical to test each pint-glass. And truth be told, most customers could not really tell the difference between a 95% pint and a 105% pint, als long as the lights were low and the craic was great. For the landlords it did not really matter, because on average the pint was a pint, and each cask more or less contained the same amount of pints, and because of spillage they could never be sure how many pints were in the cask to begin with, and they did not really care anyway. After a while they did not really want to pay for expensive 100% pint glasses, when cheapy 95-105% glasses would be acceptable to the punters. (And the reader will observe, that it soon became custom to shorten the 95-105% notation to 5% in order to save ink.) Next time you have a drink, you can ponder about that question, is this pint a pint?

Can we pleeease go back to Volts and Amps, I hear you cry…  Ok, I’m just having a great time, and since the interweb is down anyway, I might as well write a good story..

Lets recap: You just learned about the Volts and Amps and about tolerances right? Yes you do, say yes please. I don’t want to repeat all this!

A Volt is only a Volt if we can measure it with something accurate. A Volt measured with a 10% meter is not the same as a Volt measured with a 0.1% meter. That’s actually not true, the Volt is the same, what you think it is (measure), is something different.

And so we enter into the murky world of: Is What I See Really What It Is?

Or more precise: what I measure is only as accurate as the tolerance of my measuring instrument. And to shatter a digital myth here and now: Just because it’s digital does NOT mean it’s accurate! True, compared to pint-glasses, our measuring devices are unbelievable accurate. But, not as accurate as we like to believe!

Typical DVM’s have an accuray of 1% (DIY-Maplin range). Many, gadgets we use have an accuray of 3%. That bad huh.. Yup. Because standard components used in electronics have a 5% tolerance in their values. And that’s because we are so good! 10% is what you buy in the shop, but within a batch of components, the spread is probably 5 % or better.

I got 10 pcs 1% resistors the other day, their values as measured by my 1% DVM were:

99.7 99.9 100.2 100.3 100.4 100.4 Ohm. (the others were worse)

All within specs. But are they any good for what I need? (What do I need them for anyway?)

Lets build ourself a Circuit. (This involves soldering wires together, and in general having fun explaining to the hotel manager that you are only trying to test a theory. All I can say is that hotel managers in N-I do not seem to understand, and as a result I was banned from accessing the interweb.)

My circuit was nothing more then 6 resistors glued end to end. Or to put it more precisely, wired in series.

Now if I were to connect the ends of this string to a Voltage producing Gadget (A bunch of Ahmed’s bat-ter-eeeeh’s or if available, a 5 cell Lipo) a certain current will flow through these resistors. The higher the value of the resistors, the lower the current and vice versa.

Since I had the equivalent of 20.6 Volts handy and the bloke at Maplins only had 10 pcs of 100 Ohm resistors, we can calculate some important things.

6 resistors of 1% 100 Ohm, wired in series creates the same value as 1 resistor of 600 Ohm. I can calculate the current running through this string by dividing the Voltage by the resistance (Ohms). 20.6 (Volts) devided by 600 (Ohms) = 0.0342 (A). So the total current through the string of resistors is 0.034 Amps. (A common way of writing this would be 34 milliAmps. )

Ah, but this is only true is the total of all resistors was indeed 600 Ohm. Yup, and it was not! Remember, the total added up to 601.1 Ohm. You are so 100% absolutely right, but let’s keep the maths simple, just pretend for a minute it was 600, ok?)

We do remember that Voltage is Current times Resistance. V=A*Ohm. (Most tesxtbooks will show this as U=I*R, since that is the official way of expressing a Voltage, current and resistance)

We know that the current throught the string was exactly 34.2 mA. not 34.01, or 33.99, but 34.2, because our 1% accurate meter says so.

O dear, the meters accuray is 1% so it could very well be 34.543 or 33.858 and still be ‘accurate’. (And my meters scale was 0 to 20 Volts, it would be 1% of the full range. Usually the scale is not 100% linear either)

But let’s not worry for the moment. I have the only 100% accurate DVM in the universe. Honestly. And we are not really interested in absolute values, we want to know the relation of the values to each other!

So, lets say, I have exactly 34.2 mA through my resistors.

And I have exactly (as measured with my 100% accurate DVM) 20.6 Volts connected to the end of the string of resistors.

Lets do something funny. Let’s measure the voltage accross each resistor. Each resistor has a slightly different value ( my meter tells me so) Lo and behold, I measure approx 3.4 volts accross each resistor.

Wow!! so which on is accurate? The second one? Because we thinks it is 100 Ohm?

Remember, this was a test circuit with resistors that have a value that is within -0.2/+0.4% of 100. (or so we think)

And the casual observer will cry: But you started out with 20.6 Volts!! True, my meter says so, but to measure something in the lower voltage range I switch to a different range on the meter, and now I have no idea what I measure Yes, my Friends, that’s Life in Electronics. It all works on grey smoke, and no one has a clue how it manages to work at all! And I am not joking. Electronics is all about trying to make the tolerances of parts work in your favor and at best stop them behaving badly.

Using an 18 Volt supply (giving me a 30 mAmp current) to make the maths easier I can see that:

Above is what you measure if you use standard 5% resistors. Shocking, right? Yes, indeed.

Below are the values you can expect using standard unselected 1% resistors.

It gets worse. In the above example I use a 100% accurate Voltmeter.

What happens if I use a meter that has an 1% accuray (as in: value could be +/-1%)

So, worst case: my 3.000 volts could actually be somewhere between 2.95V and 3.07V and still be within 1% specs.

3% components give me anywhere between 2.83 and 3.19Volts. And so far I have only used a single voltmeter.

If you use a circuit that has to scale voltages to be able to be measured,.it really gets exciting.

Scaling is often/always needed, because most voltmeters only have a certain range they can measure. In our world of digital wizardry, a common range would be 0-5 Volts. To measure higher voltages, one would introduce a voltage devider, (as the names suggests, it divides one higher voltage to a lower one, that fits into the range of our measuring device. ) Of course all these components have a tolerance)

I’m sure by now you see that we actually have no hope at all of measuring anything at all with any amount of accuray.

But to return to the beginning of the story, the Missing Volts.

This whole ramble was caused by one of our esteemed clubmembers mentioning the fact that one cell in his LIPO’s always indicates a higher value on his measuring thingy.

Since it happens on all packs, my suspicion is the measuring gadget. And without feeding it with some accurate voltages to test it, we do not know what it measures!

To be continued, errors fixed, and story completed with more results!

Kees

Below is a speed estimate taken from a recording of Brian McCartan’s Dara 20 at the field, as you can see, the figure comes out at 240km/h or in old money a hair under 150mph!!

What have you got??

Measuring the Doppler effect (change in sound frequency) during a low pass to give a speed reading

Brian’s Dara 20, not a lot to keep an eye on at 150mph!