Wednesday, March 29, 2006

Policy statement from the SAMAA Management Committee on the use of the 2,4 GHz radio spectrum

Cell phone technology is now catching up with our model radio control equipment and these new systems are soon to be released onto the South African market. It is a Spread Spectrum transmitter and receiver operating on 2.4 Gigahertz band.
A similar three-channel system is already on the market and is being used very successfully in model cars. The latest development is a six-channel, 10 model memory set designed for small model aircraft. The transmitter has all the usual trims and mixers, and except for the short stubby aerial, it looks very much like the standard 35mHz equipment we are used to.
This equipment has been in use in the USA for a while with encouraging results but there are quite a few limitations with its use
The 2.4GHZ band is license free and the use thereof does not need to be approved by ICASA or SAMAA.
For those who are interested in the workings of these sets, some of the finer points are as follows: -
1) They use some 80 spots on the 2.40Ghz band.
2) When switched on they automatically search and find an unused open spot and latch on to it.
3) The transmitter and the receiver must be "bound" to each other before its first use. Once bound the receiver will only obey the signals from its "bound" master transmitter.
4) More than one receiver may be bound to a transmitter
5) They operate on that spot almost interference free (according to the manufacturers)
6) They have a range limitation, dependant on the weather, the terrain and the number of sets of the same type transmitting at the same time.
7) The useful operating range of these sets reduces with the number of sets in use at the same time. (These range limitations are still to be verified and confirmed but with many sets in use simultaneously, it could be as little as 200 metres).
As these sets are coming, it is inevitable that they will appear at our flying fields, so it is proposed to set down a frequency control procedure for SAMAA registered clubs to control these 2.4ghz sets.


1. 2.40ghz transmitters are approved for use at SAMAA registered fields.
2. The frequency control system of "Card/peg on" or "Card/Peg Off" will remain in force.
3. When not in use transmitters will be switched off and returned to the TX pound.
4. A maximum of four (4) 2.40ghz sets may be operated simultaneously.
5. This radio equipment may only be used with Shock Flyers, Park Flyers and Electric Micro Helicopters.
6. Any of the model aircraft types specified in (5) fitted with this equipment should not operate at a distance of more than 300 metres from the pilot when flying at a SAMAA registered field.
NOTE. These are provisional rules only and may change, as and when the equipment in question is in use and other limitations, if any, are found.
For the frequency control board at the clubs, the suggestion is that a sticker be made in Green and marked "Spread Spectrum". This sticker will cover pegs on the frequency board and could be applied over some of the now extinct 60mHz frequency spots.

Tuesday, March 28, 2006

March Model Massacre -- Lionel Brink on the second Highveld Thermal League

The two days of low cloud and drizzling rain did nothing to dampen our spirits prior to Sunday for the competition which yielded a record HTL field with some of the best flying and weather we have had all season. With a friendly atmosphere and relatively challenging albeit informal format, the Highveld Thermal League proved again to be one of the finest intermediate level competitions on the MGA calendar.
Read more, 650k pdf.

Monday, March 20, 2006

The Sterkfontein Slope -- Charl Viviers

It started with a met report predicting 10kts out of the north and a short trip to Evan ‘Lead-Foot’ Shaw’s house, at the base of the slope, to pickup Piet ‘Prepetation’. With Evan mumbling something about having to join a fuz first, Piet and I took off to the slope. The off-road track to the slope gives new meaning to the phrase boendoe bashing, but my trusty Bantam served us well......
Read more here , 320k pdf -- the photos are quite large

Tuesday, March 14, 2006

2006 Black Eagle Slope Weekend, the whole story from Evan Shaw

Link to Evan's loooong write up, Sixty pages of photos and thousands of words. The bad news is that the pdf is about 7000k in size.
Worth every bit of time spent though, it is a masterly piece of work.

Monday, March 13, 2006

2006 Black Eagle Slope Weekend

The flag men and woman at base B during the Zagi racing.

Thursday, March 09, 2006

Wednesday, March 08, 2006

Full set of gliding postal results from John Lightfoot

Link to postal results

2,4 Ghz DSM radios

First from Wessie vd Westhuizen:

DSM 2,4 Ghz radio legality

Just spoke to Bob Skinner, so you can take this as the OFFICIAL SAMAA standpoint.

The Spektrum system DSM radios are 100% approved, and you are covered insurance-wise if you are using these systems.

SAMAA reccomends the following :

That Clubs have a GREEN area on their peg boards, where DSM users can place their peg, to indicate that wide spectum users are flying. (this is their only must-have provisio, Club managers take note)

That no more than 4 DSM systems are in use at the same time at one field, as the range of these systems is influenced by the number of users.

That's it.
From a HOBBY SHOP and FLYER point of view, we encourage the DMS systems to be used for PARK FLYER applications only.


Now a technical view from Mike vos:

I have a lot of telecom experience in the 2.4GHz band...or shall we say headaches or maybe even nightmares.

Tom, you made a good comment…do you need a peg for your Blue Tooth? What is that ­ I thought someone mentioned the colour green. I think rather use red. Or polka dot or stars, because you will see more of that…..maybe green was the right colour….The Grass…oh so painful.

The 2.4GHz band is known as the ISM band. Set aside for Industrial, Scientific and Medical apparatus generating noise. Any device in this band must accept the noise levels of the band ­ not protection will be provided.

Although it sounds quite romantic the way these sets select an open channel and avoid the interference consider the full picture before you sell your 35Mhz on next week's hot specials. Equipment like these radios, wireless video cams, WiFi, BlueTooth other wireless links and network equipment could not be properly managed by the regulators so they said go manage yourself. It is something like opening all 6 lanes on the N1 (Pta to Jhb), yes North Bound and South bound and you go pick your "free slot" and get to the other side. You might just get there. But size is going to matter.

Consider this: The radios probably transmit something like 100mW, similar to WiFi equipment. (the legal approved ones ­ not the ones people put up with large grid pack antennas making them illegal in power output) These devices look to each other like noise. So the more radios the more noise and thus distance comes down. Maybe this is where the park flyer caution comes in…stay close. Now….Switch on your Microwave Oven! 1000 Watt!! 10 000 times the power, slap bang in the 2.4GHz band. The pie is going to be nice and warm you are going to buy now just after you pick up the pieces. There are illegal links running many kilometres and ICASA can't close them all down, they pop up everywhere. So with 4 pegs on the green board….what about the link running over the club's flying field drowning your radio's signal when you pass through it.

To go back to Tom's comment. Why even put up the green space? Why stick to a club's flying field? Any one can switch on his Bluetooth, WiFi router or Microwave oven without telling the neighbours.

So be careful ­ this band is VERY much FULL of INTERFERENCE but only looks like noise and as long as you can see a bit of signal you maybe ok. I will certainly not try it out just yet. The radios do seem to have great features.

I just think that after the first couple of pilots are going to try those on planes this group is going to make nice entertaining reading, please add pictures and video….uhm, will that mean then just 3 planes in the air? Just do not mail it with Bluetooth then only 2 planes can fly.

A word of warning from Eric Arnaud

Just a word of caution,

I bought a Rc plane from one of the advertisers on sarfly, one of those radio+plane thingy jobbies. Plane package R 399 + R100 postage.

Turned out the range was crappy and the plane would not fly more than 10m away ! Contacted the guy and asked for some assistance. This is the reply I got

""All goods come with a 24 hour, self test guarantee."

So as you can se there is not much I can do, you are welcome to return it at your cost for postage, as well as the return postage at your cost, so I can take a look at it. If I am unable to solve the problem there is not much I can do, sorry about that."

So as you can see, another R 200 on postage back and forth and I may as well buy another from a local Junk shop in Randburg. Just be careful what and where you order, as Charl says, if its available locally in your area, and it costs a little more, pay the price but at least have the no nonsense return or exchange policies, as they carry the volumes and are willing to exchange.



Monday, March 06, 2006

Gliding Postals -- Pam Lightfoot

John is in hospital but has asked me to send out the results below just to let you know the rest will be sorted out/posted when he is back home which hopefully will be next week.


1 C. Goodrum MMS 2291 0
2 A. Sneedon DMAC 2280 0
3 M. Stockton MMS 2251 0
4 T. Potter DMAC 2187 0
5 P. Rheeders BERG 2187 0

1 Midrand Model Soarers 6671
2 Durban Model Aircraft Club 6476
3 Black Eagle Radio Gliders 5873
4 Southern Soaring Club 5517

Unallocated subs payments

Please help Bob Skinner if you can with these subs payments he has been unable to identify.
Here's a link to the splendid version of the information, a 700k pdf.
Here's a link to the utility version, 120 k pdf

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