Have you all rushed out and bought crystals for the new frequencies then? Did you manage to find any? No doubt you are all thanking the powers that be for their generosity. Well, maybe we can change that.
A few years ago (actually, it was six and a half years ago - doesn't time fly when you are having fun?), when we were granted the new 35MHz band, there was an understanding that we would receive more frequencies when the existing users had moved. The figure mentioned then was 'another 100KHz' - in other words 10 more spots at 10 KHz spacing.
As one might have expected, nothing more was heard of this. Then a certain member of the SMAE R/C (power) technical committee, well-known for his embarrassingly long memory, began asking questions (modesty forbids the mention of his name). As a direct result of this, it only took a couple of years to obtain some more frequencies. Ah, but whats this, only five more channels, oh well, all right then, we'll give you one at the bottom end and make it six.
In this day and age I suppose we are becoming used to waiting a long time to receive half of what we were promised, but we don't have to like it do we? It remains to be seen just how long it will take for all manufacturers to make suitable crystals available.
Like I said before, no doubt you are all truly grateful.
I have heard that some clubs are considering the possibility of giving the new frequencies to their helicopter flying members and sending them away to one end of the field. If you dislike your models so much, why not save a lot of effort and just jump on them!
Modern R/C equipment is undoubtedly very good, but it cannot do the impossible. Simultaneous operation on 10KHz spacing is just about possible with a great amount of pilot discipline and everyone using identical equipment. Introduce the usual total lack of discipline and several makes of equipment in use and 20KHz spacing becomes very dodgey.
There are several other effects, now becoming understood, which suggest that operation on much wider spacing needs care - one such being the so-called 'third order intermodulation' which is currently giving our American cousins lots of headaches.
So, send one section of your club off to the other end of the field on any set of frequencies and you are going to have problems. Particularly if those frequencies are ones which the equipment was not designed to operate on in the first place.
Or look at it another way. Why should one particular section of your club be obliged to fork out for new crystals, which may be difficult to obtain for a while, anyway?
This column is no place for technicalities (thank goodness!) but perhaps a simple explanation of the term 'third order intermodulation' may not be out of place.
Put in its basic form it means that any three transmitters which are operating on equally spaced frequencies will cause interference to the two outer frequencies. In other words, if three people are flying together on, say, 68, 70 and 72, there is a possibility of numbers 68 and 72 experiencing interference. The spacing is not important - 62, 70 and 78 may produce problems for 62 and 78.
In the USA, where they have been granted a number of new frequencies in the 72MHz region, the problem is serious enough to cause a drastic rethink of their whole frequency control system. While we have not, so far, become aware of the problem in this country, it may well explain a lot of 'funnies'.
If anyone has any experience of effects which may be due to this phenomenon, I would be pleased to hear from you.
We have been rather heavy this month so how about a little anecdote not entirely unconnected with the second item above.
There is in our club a gentleman who is renowned for his superbly painted R/C scale models. These are invariable of highly unsuitable subjects (short noses, sharply tapered wings, etc.). Unfortunately, these are the only types he is ever seen with and it is perhaps not too surprising that he is a little light on actual flying practice.
So, there I was, indulging in a little aerobatics practice when I became aware of the approach of the gentleman concerned with one of his creations which he was obviously about to fly. Since I was flying at some height and distance this did not seem likely to cause any problems.
There followed the usual take-off and turn left technique followed by a flight which circled round and round the two of us at quite close range. It was immediately apparent that the motor in the model was much too lean and I expected that the model would soon be landed - but no. This was rather inconvenient since I could not hear my own motor.
Several circuits later, with the motor in the scale model becoming sicker and sicker, it eventually stopped, much to my relief. I was totally amazed to see the model immediately turned downwind - whereupon it stalled and crashed into a field of corn.
Having finished my flight and returned to the pit area I observed the return of the damaged model. A club member enquired as to its condition and received the reply, "Smashed to pieces. Bloody helicopters, I couldn't hear the motor!"
Oh yes, didn't I mention that I was flying a helicopter. Does it make any difference?
I was fascinated by the account in the July issue of Clive Hall's camera plane which was used to film wild birds (er, feathered variety). What I find to be totally amazing is that the subjects of the film were quite unperturbed that one of their number was cheating by utilising an OS 40 FSR to help it on its way! Perhaps there is to be another episode dealing with the development of the silencer.
The technical specification was also quite interesting. For instance, the wing loading is given as 20.8. Great, but 20.8 what? Grams per square mile? Tons per square centimetre? And the avionics consisted of aileron, elevator and rudder. This suggests even more revolutionary principals to be unveiled. Why no throttle, I wonder. Come on Clive, give us the real gen.
Note for younger readers: 'Gen' is an old fashioned and now little used slang term for information.
We must apologise for the missing caption to the photograph included with the July column. This was of the legendary Obie St Cyr in the process of unwinding the lines in preparation for the first ever control-line flight. The passengers in the fuselage are two brothers named Wright and the gentleman applying the helping foot is Jim Walker.