Tuesday, October 18, 2005

Hermanus slope weekend update from Ross Leighton

It’s that time of the year again and we have about 6 weeks to go until the slope soaring event of the year – the AFC Hermanus R/C Slope Fly In 2005. This years’ event will be held as usual on the last weekend of November (26/27th) at the car park next to the Vodacom Tower on the Hermanus Hill. The road to the tower is called Rotary Way. You turn left off the main Hermanus road, just before the Spar Shopping centre, through a set of white gateposts. Flying starts 09h00 and ends 17h00 Saturday and 09h00 until 15h00 on Sunday.

As usual there will be two flight lines, one for scale, moulded and built up gliders and one for combat and special events. We will be giving pylon racing a go this year and there will be several classes to cater for all types of slopies. Should be fun and we’ll see who is the real “King of the Hill”. As usual there will be prizes galore and of course the popular spot landing competition.

Safety is well taken care of with our usual Tx control caravan, air bosses and frequency board. Overall safety is in the capable hands of Bobby Purnell.

There will be the usual Saturday evening braai at the Hermanus Cricket Club, starting at 19h00. Order you braai pack when you register.

Register online at http://www.atlanticfc.org.za/ under the Hermanus 2005 section. You have to click on the register button and you will be taken to a new site where all you do is enter your SAMAA number.

Hope to see many of you there but book early because as usual numbers attending are limited to 120 pilots.


Ross Leighton
Atlantic Flying Club
Cell: 0828813183

Chris Theron's report on the 2005 Limpopo Aerobatic Championships

Link to the report (150K pdf)

Monday, October 17, 2005

In flight electric heli measurements from Andre Kilian (the man is a gold mine of info)


I downloaded the in-flight data from Paul Coelho's T-REX last night. Flight included very little hovering, mostly loops, rolls, upside down flights etc. - he was pushing the little chopper to its limits!

Average current 9.2A, max amps 22.5, max voltage 12.5V, dropped to 10.1V under full load, avg 11.02V Max power 244W, avg 101W, 1595mAh used from battery.

As a matter of interest - flying gentle circuits gave the following results: Max current 12.99A, avg. 8.54A, max voltage 12.6V, avg. 10.96. Eco 8 (same flying style) max current 19.36A, avg. 12.89A, max voltage 13.57, avg. 10.61, min 10.01V (old GP3300 cels).

Also interesting to note that if you only intend to hover and fly gentle circuits, a 10C cell like the Hecell 2000, Align 1800 or the E-tech 1700 are fine, as amps are below 15A. If you intend to push it, go for the Kokam 2000 packs (15C) or for even better performance the the new 20C cells such as the PQ 1800 (22C) or the flight power 1800s (20C).



Saturday, October 15, 2005

SAMAA AGM and election of Management Committee

The SAMAA AGM, held today Saturday 15 October 2005, ratified the election of a new Management Committee.

The members are, in alphabetical order:

Dave Armitage
Dirk Meyer
Keith Nicolls
Marietjie Skinner
Ludwig Steyn

Joe Coetzer is automatically a Committee member by virtue of his position as immediate past Chairman.
Bob Skinner remains General Manager.

Congratulations and Good Luck.

Wednesday, October 12, 2005

CRF Maandelikse Akrobatiese Byeenkoms -- Pierre Fouche

Link to the report (40K pdf)

More on LiPo batteries from Andre Kilian


As more of the hi-rate lipos (15-20C) packs are becoming available in SA, just note that dropping the voltage below 2.7V per cell, even momentarily under load, can permanently damage your cells. You can thus have a situation, for example, where you only use 1450mAh from an 1800mAh pack, but damage your batteries in the process ("fat pack" syndrome - normally fatal!).

It is thus not only important to stay within the capacity limits of your batteries, but also above the minimum voltage limit. This is normally not a problem when using a good quality speed controller which shuts down the motor if the voltage drops too low (Lipo-cut off) but may become a problem when using more than 3S lipo packs (normally with a separate receiver pack), or when the cells become imbalanced.

Also note that we are having the same race with Lipo ratings (e.g. 8C, 10C, 15C and now 22C) that we observed with the capacity rating of the Nicad/NiMh batteries. Some battery manufacturers are claiming very high C-ratings for their batteries (some are honest enough to admit that they are peak ratings and not continuous ratings) but watch for that voltage drop under peak (burst) loads! If the voltage drops to below 2.7V per cell (i.e. 8.1V for a 3S pack) you can kiss your batteries goodbye...

Don't count on the prop unloading in the air to reduce the current, as other factors such as the motor heating up may also play a role. - I have measured 46A in flight with my Acrow Wot, whereas the static current draw was about 40A (15% increase!). If anybody is interested in actual flight data or needs evidence, send me a message and I will mail you the graphs with in-flight data and/or a photo of my collection of "fat packs".

The bottom line is be wary of the "el cheapo" brushless controllers and hi-rate cells that are now flooding the market, as a bargain may turn out to be very expensive. By all means, use these cells and controllers (some offer good value for money), but be aware of their limitations and the fact that the harder you push your lipos, the shorter their operational life will be.

My advice is to measure the current on your setup, and stay within 80% of the continuous current rating, and if you are using more than a 15C pack or more than a 3S configuration, ensure that you buy batteries with pigtails so that you can check the individual cell voltage for imbalance.


Andre Kilian

Wednesday, October 05, 2005

Tuesday, October 04, 2005

SAMJA update from Zane Mannell

After much deliberation and loss of blood, the SAMJA committee has been chosen:

Chairman: Boet "BVM" Denysschen
Vice Chairman: Johan "I'm on pension now" Ehlers
Events co-ordinator: Andy "Nosewheel" Keil
Webmaster/PRO: Olaff "Spiderman" Schoeman
Secretary: Paula "Weighless" Denysschen
Treasurer: Zane "I killed the Eurosport" Mannell

Everyone is urged to have their say here. It is a democratic forum and can say what you like about us - we will get you later!

Seriously though, it always seems to be a Vaalie Association, I am only here on loan to them just to show them how it is done! We want to ensure that everyone has their say(at least 20 cents worth - I am generous!), Cape Town, Durban, PE, Upington, Outshoorn, etc. If you don't, it is not our fault! Forget who likes who and what make of turbine you fly or who you bought it from, we want to hear from everyone who has something to say, good bad or ugly like me! I know that we can't please all the people all the time but I am sure that we can find common ground.

We are working on some stuff for people interested in attending the World Jet Masters in 2007 which will be held in Ireland. Unfortunately (or maybe fortunately) WJM is only held every second year. I have said that we need to meet with the guys that flew in this year WJM and learn from them. We do have the building and piloting skills necessary to do well in this competition. I have already spoken to the guys(Glen, Greg and Mark), OK I have'nt spoken to Glen directly but he will co-operate or else, and they are willing to share their experiences with us. Johan Ehlers has suggested a date after March 2006 as there is an International Judging clinic to be held overseas next year in March would could help us as well. Obviously the subject (aircraft)chosen is important to ensure that you stand a chance. There is no-way you can make up 100 static points in the flying rounds! So there will be a workshop held and I will keep you updated.

Direct all your abuse directly to me!

All for now


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