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Thursday, February 26, 2009

Final notice of BERG AGM (2009)

Hi all BERG members, please note that our annual AGM will take place after this months Postal competition at the BERG field on Saturday the 28th of FEB 2009. This should be at round 2pm-4pm in the afternoon. We will be electing new committee members so you will have your chance to vote for them.

Please send your nominations for the 2009 committee to I will make myself available for Chairman this year, but you are free to nominate any paid up and in good standing BERG member for this position.

Other positions that need to be nominated or reconfirmed are:

and Safety officer.

Please note that the agenda for this years meeting, chairman's report and the minutes of the BERG AGM held on the 23rd February 2008 last year can be found in the BERG vault via this link . BERG vault Thank you for you cooperation.

Piet Rheeders.

Monday, February 23, 2009

E-Tsotsi sets new unofficial SA electric glider XC distance record

Some time ago Evan asked me if I would like to go to Volksrust in Feb as the MGA calendar showed only RES and Postal club competitions. Anyone who has done any slope flying before will think twice before declining an invitation like this. At work, Philip Otto also wanted to go and his intention was to take his whole family with.
In the above photo you can see the northern side of Tamatieberg in the background..

I had recently just finished my E-Tsotsi and knowing the conditions on Volksrust can be light, it was a sure selection to go with.
Lately there had been a lot of discussion on the MGA Chat group about South African Records. More research showed that there was no official XC electric glider record. So I decided to give it a go and try and establish a new SA Electric Cross Country glider record. I informed the MGA of my decision and they gave me the go ahead.

I had more than one course in mind and the one that I would use would depend on the wind on the day.
We arrived later than normal at Vloksrust at around 12PM, to find a nice NW wind blowing up the slope. Philip, Izak and Norbert were already having great fun.
I had one flight with my 2M CMP Omie and then did a test flight with my E-Tsotsi to confirm trim settings, CG and range. Everything work okay and I landed to recharge the lipo battery for the intended distance attempt.
Shortly before 4 PM the wind dropped and swung from NW to West. At this stage I realised that the conditions below the mountain on the flat field would be perfect for the XC attempt with plenty of daylight left to do the run.

We packed all our slope gliders first and left the E-Tsotsi to pack in last.
We descended the mountain to the start point.
Evan assembled the E-Tsotsi and at 5.51PM James Shaw my Spotter, Timer, Helper launched the electric E-Tsotsi on it way.

There was hardly any wind but while flying the course I could feel a slight crosswind from a westerly direction. This I countered with the rudder when needed. At this stage of the day I did not expect any major thermal activity and on my first glide down James informed me of birds circling straight ahead on my glide path. I opened the throttle for a brief run. The end result was that the E-Tsotsi shot up and must have gained 100 meter or more with only a 5 sec run without any circling. This gave me at least a 7 km of distance gain.

Meanwhile, Evan settled down to a steady 45 kph with the Garmen GPS displaying the actual and average speed as well as distance traveled. Behind me Robyn, James girlfriend, was taking pictures as we moved along. Above us slightly to the left the E-Tsotsi was flying like it was on rails. I can only attribute this to the fact that the air was very stable and smooth (Charl describes it as “Campaign air”)

Every time, after a motor run, the E-Tsotsi would decent to a certain height and then, as if was floating on a cushion of air, would maintain height refusing to come down.
It was this conditions, plus the lack of sink that made the kilos go by and never did I once circle to try and find lift.

Evan Assembles the E-Tsotsi

James about to launch the E-Tsotsi

Above and slightly to the left.

James scanning ahead for any lift or obstacles.
Just after a motor run. Nice and high.

Amersfoort - Straight ahead

Evan driving - Nice paved tar surface all the way.

Me, craning my neck out the side of the Kombi.

Plenty of landing along the way.

It was not long before we passed our intended landing point of 25 kilometers.

James checking the GPS

With the conditions being very good, I decided to carry on and 6 km later flew past the town of Amersfoort. Unfortunately, 4km after Amersfoort we were forced to came to grinding halt, with a Stop/Go traffic control not in our favor. I got out of the Kombi and circled overhead while waiting for the light to go green. After a while I had to make the decision to end the flight as I had no telemetry equipment on board and could only tell from the last motor run that the battery pack was nearing the end of it's charge. (Never mind the fact that any cars approaching from behind would not appreciate the fact that we would be crawling along at 45 kph on the narrows single lane)
Circling overhead
The landing presented no problems and just under a hour after take off, much to the delight of all the occupants of the cars that lined up behind us, I landed the Tsotsi in a field next to the road.

Nice big landing field
On approach

The whole team shook hands and while Evan and I recorded the GPS information, James and Robyn dismantled the E-Tostsi. All the relevant information will now be forwarded to The MGA for ratification and acceptance of the attempt.
GPS data

As we returned to Oom Louis place I saw a typical sun set scene that just put the cherry on top of the cake of a really flawless flight and just a great team effort.

Only, on the way back did I realise how far this little 2 meter plane has gone.

To Evan, James, Robyn (for all the lovely photos) and Kayleigh (for refreshments) a big thank you for assisting me with this flight. You all are definitely on my list for the next attempt.

For the Record

Distance flown in a Straight Line: 35.1 km
Distance traveled by road: 36.3 km
Time: 53 min 59 sec
Moving average by road 43,1 kph
6 Motor runs
Total accumulative Motor Run Time: 5min 59sec
GPS data
Start point: S 27,17.117 E 29,53,786
End Point: S 26,58,16,7 E 29,51,502
Equipment used
Battery: Lipo 2100 maH 3 cell(11Volts)
Scorpion brushless motor 550 watts
Scorpion Speed Control 35A
Prop: Graupner thin electric folding prop 13X7
2xGWS servos 1.3 kg
Rx: JR 770RS
TX: 9x2

Tostsi Airframe Data

Wing span: 2meter

44.16 sq dm

Total weight 1080 grams
Wing loading 24 gms/sq dm
Aspect Ratio 9.24
Designed by Evan Shaw 2003.

Tuesday, February 17, 2009

BERG BLOG counter hits 45,000 and E-Tsotsi takes to the Sky.

On Sunday my E-Tsotsi had its maiden flight in perfect weather, and as a bonus the flight lasted 45min and I used about half of the 2000mh battery capacity.

I hand launched the E-Tsotsi (just to confirm the glide trim settings and CG) and on the second launch opened the throttle and she just climb up vertically just like Tony’s Tsostsi and within seconds was at twice the normal winch launch height.
At this early stage of the morning (around 9.45 AM ) the lift was only starting to developed and I only got into good lift after the 3rd motor run. Then I settle down in my camping chair and at times had to dive it down as the lift got stronger.

Once the motor was cut it flew and thermal like a normal Tsotsi and the only improvement that I can make now is to move the CG slightly back as for the first flights I prefer a forward CG.

Unfortunately on the second flight I had some RX lock-out trouble (PCM - Positive Crash Mode) and the Tsotsi sustained some minor damage on the fuse and wing. But I have already repaired it and it is once more ready to fly.
As I did this post this morning saw the blog statistic counter roll over to 45,000 hits and once again a big thank you to all our contributors and blog readers.

Monday, February 16, 2009


Charl,Peter Karner , Peter Eagle and I went out to get some Aerotow tips from the Glider pilots at JOMAC.
Their tug has the same 50cc petrol motor that Peter has for the Cessna 185.This combination works for gliders up to 5mtrs no problem. Our next steps are to put some
tow releases into some smaller gliders and start practicing.

Friday, February 13, 2009

Rudolf's latest aviation project

Extracted from mgasa chat group:

Rudolf posted:-

My latest aviation project.

Comes with a onboard flight computer, navigation system and homing beacon.When it gets launched it always returns in the evening. Sometimes only the next evening.Flies well indoors and outdoor but better suited for outdoors.

Not a very good glide ratio but does good in fast turns.My wife loves it and gets more time with it than me.(It only has got eyes for her.)

She says its cute!!!

Izak Asked:-

Mode 1 or mode 2..... ?

Winch launch or chuckie...?

Bet that Model Aircraft design book in the pic was useless in the design of this complex project..... ;o)

Rudolf replied:-

No mode required. (Autopilot) Chuckie.

Aerodynamics is a big problem.Loads of down wash in hover mode and it keeps loosing tail feathers. At least when it flies out of range it returns.

Wednesday, February 11, 2009

Urgent Message to BERG members

This message is for all B.E.R.G. members ,there is a problem with our bank account
please DO NOT pay in your annual club fee of R200 until futher notice. We are sure the promblem will be resolved shortly, and will keep you posted.
Many thanks

Monday, February 09, 2009

Wing Joiners/Celstar

We are able to see on the BERG-blog which pages get the most hits, and funny thing one of the popular ones is the making of the huge wing joiner for the big DG500 , this was a blade type carbon joiner, but I use the aluminium tube/carbon joiners system on all other projects and these are easier to make.
So as I needed to make new joiners for the Celstar I took lots of photos and will explain this simple way of making wing joiners for scale gliders up to 6mtrs.
I have been asked if a square joiner would be less likely to allow the wings to flutter, in theory that is true , in that the wing with a square tube cant rotate, but with a tube and a good locating pin setup I think the round joiner have the advantage in that the wing incedence can be altered totally and also between the left and right wings, with a square tube ,if built badly, it cant be adjusted as easily.
The aluminium tubes I use are available at most good hardware stores and are available in a variety of sizes with each outside diameter fitting within the next size I/D.

The small tube with a carbon tows filler works well on gliders to 4 mtr, the next size up tube
goes in the fuselage and in the wings. Size two with carbon will suit gliders up to 6mtrs, as the joiner and the largest size then goes into the wings.
If you choose a thick airfoil for foam wings, you can install the joiner tubes from the top of the root to the bottom skin and this will give the built in di-hedral , with a flat joiner.

The joiner tube is cut to size and any burs removed, Dremel, file or sand paper smooth.

The tubes are masked with tape.

The carbon is cut double length like a U , then I tie on some strong nylon line and check if dry they will pull through the tube, you can have a small gap to allow for the Epoxy .

I wet out a few carbon tows , at a time and use a slower curing epoxy to give plenty of working time. I picked up a problem with the bigger joiner as the wet out tows would not fit through, solution was to remove 4 x tows at a time until it just fitted. You need a handle of sorts, as every thing is slippery , I used a piece of cut tube to make a T handle wrapped with some tissue.
The big joiner has about 80 x 60k tows and the snaller one about 35 x 60K tows.
Epoxy was LR20 and harderner was SLC 60.

As always when working with epoxy ,wear gloves.
Once cured overnight, I trim the ends and clean off the masking tape ,you now have one very strong joiner, the big one weighs 447 grams but will be probably be the most important part of a 6mtr sailplane (the elevator being a close second).
The smaller one weighs 260 grams, and will go into the Celstar.

B.T.W. the standard carbon joiner of 16mm diameter as used on my 6mtr Ventus did not break
during a verticle dive into the mountain side during last years Sungazer which destroyed the rest of the plane.

RES & Postal Round 1 at BERG

The last 3 weekends has really delivered very good weather at the BERG field and Sunday the 8th was no different and once again we had a good turn out. I counted
no less than 12 car’s.

a Good BERG turnout for postal and RES competitions.

I left home early so that I could setup the club winch and spots for the RES and postal competitions and by at 9.30 AM had already flown two test flights. Like Craig, I have also
decided to fly my 2 meter Tsotsi in the Postals this year. I will fly my trusty 2.5 meter Tsotsi in the RES competition. (The 2 met is RE only) The test flights indicated to me that air was already buoyant and shortly after that Herman and Toni arrived and we started with flying the postal flights. Herman timing for me. At this stage there were no cloud cover and the lift was easy to find.

Tsotsi's galore (In front my 2.5 meter, in the middle my 2meter Tsotsi and in the back PJ 2 Meter Tsotsi)

I did not want intermix my RES flights with the postal flights and therefore stated straight away with the postal flights. The weather improved by the moment and I strung in the flights one after the other. By 11.30 some cloud cover set in and the good lift, that I had, disappeared and after 4 max’s. My 5th and last flight I flew into sink that my 5 year old willing Tsosti just could not survived and landed with a 1.49 on the clock but a good 2 meter spot.

With the postal score now done I started with the RES flights and straightaway, because of the cloud cover, struggled to get the required time of 8 min. At this stage decided to wait
until the weather improve as it was only Midday (12.00 AM). One had to read the conditions more carefully. Typically one had to wait until the sun appeared form behind the clouds and then after a minute or so, launch and therefore the next 3 flights were good. This tactic worked, but on my last flight the sky was total covered with clouds.

On the 5th flight I once again struggled and did not make the time. My 2 throwaways rounds were now used up and I just had to fly well on the last flight to do well. And at 3PM decided to go for it as the air did no feel cold. Although I did not hit a boomer I ran into some smooth lift that lasted the whole flight and I even had to dive the glider down to land close on 8 min.

Mike Launching his RES Pathfinder and Blake timing.

Mike, with his RES Pathfinder, started even latter than I did. (after assisting his son Blake with normal postals) He was faced with similar conditions and was also flying well. He had to really wait for conditions to change for the better before his last flight and in the end, the only difference between us was 6 sec after two throwaways.

Unfortunately this guy was disqualified as he had 2 jet engines and not 2 spoilers in the RES competition.

I must admit, that of the two formats, I found the RES postals more challenging because of the working time format and will definitely recommend this as intermediate step before one goes on to the HTL competitions.

Blake timing for Mike.(RES Comp)

Wolfgang says Hi.

Tony's fling in full flight.

Thursday, February 05, 2009

F5J - E-Tsotsi (Nicknamed: "Yellow Bird") almost ready to fly

There is a saying that goes around about the famous J3 Cub that asks, "What is there better to fly than a J3 Cub?" Well, the answer is another J3 Cub but with floats on.

So I guess one can modify this question in a similar way when it comes to a 2 meter Tsotsi. “ "What is there better to fly than a 2 meter Tsotsi?" Well the answer is a 2 meter Electric Tsotsi or E-Tsotsi.

Maybe I have lost it. Ever since I flew Tony’s Tsotsi at the Nat’s last year it almost became an obsession to build one and if you've ever seen the way this bird goes up, you will understand my obsession. Ask anyone that has witnessed this bird taking to the sky. To say the least, it is just fascinating to steer it vertically up into the sky for 20 or 30 seconds then cut the motor, hand the Tx to Tony and watch him glide it for between 15 and an 30 minutes before it needs another boost up in to thermal land.

Well to say that one has an obsession for something is one thing and it’s something else to do something about it and that is what I have done. Maybe the long way around (I stared off making a mould first) and that in itself was a challenge. But is was well worth the effort for in the last 3 day’s of my leave in December, I turned out 3 complete fuselages.

Now there is one thing you have to keep in mind when you want to go up quickly and vertically and that is to save weight wherever you can. It is for this reason it took me 3 times before I got a fuse that came out at 158 grams. Evan help me with wings and at 366 grams is the lightest set of Tostsi wings that we have build to date.

The all up weight so far is just over 1 kg and the Scorpion electric motor can swing a 13 X 7 Graupner folding prop giving 1.5 Kg Static trust, and close to 1.8kg dynamic trusts. So I have no doubts that it will perform as well as Tony’s Tsotsi.

I hope to have the “Yellow bird” in the air within the next 2 to 3 weeks.
In the mean time I cannot wait much longer to see it fly.

The 13x7 folding prop develops 1.5 KG static trust.

The tip that I believe makes the deference and it is well worth to go the extra effort to add on. I used 49 gram glass to strengthen the tip and I still have to paint it to add the final finishing touches.


There's one similarity between the "Yellow Bird" and a J3 Cub and that is the are both canary yellow.