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Tuesday, October 30, 2007



The build thread of the big DG500 continues, this post is about building the brute wing joiner out of carbon tows and epoxy. This method can be used for smaller wing joiners also.
The design differs from the joiner that I used on the Ventus which was round 19mm dia and about 75 x 60k carbon tows went into the mould. The advantage of a round joiner and tube is the ability to adjust the incedence of each wing and line them up accurately (I check the trailing edge).


On this joiner I decided to go for something much stronger and more blade shaped as the rigidety is required in the verticle plain. The joiner boxes will be made around the joiner and these continue well into the wing forming an integrated spar/shear webs as a box structure.
The airfoil is thick enough to accomodate a 40 mm high joiner and the outer joiner box.

This method will require carefull alignment of the wings to the fuselage.

The picture illustrates all the materials required for this important component.

From left to right.
RamRelease wax, acetone ,pocket scale,mixing sticks,box of latex gloves, bobbin of 60k carbon tows,lr20 epoxy and slc30 harderner , mixing cups and scissors. Finally some off cut 40x25mm pvc trunking as a mould.
Cut a suitable length of trunking and wax the inside, I have not buffed this off as finish is not important.
Now discard the gloves you may have worn when polishing, and with clean gloves cut a batch of tows , I cut 100 for the first layup wanting a joiner at least 10 mm thick by 40mm wide.

Now mixing a 50 gr resin and its harderner you need to wet out the tows as they get layed into the trunking mould(you can even fashion a mould out of balsa and line it with tape and wax)this may require a lot more finishing though.

I carefully stipple the resin, into the tows and every 3 tow layer I flatten the tows with a mixing stick, this also moves any excess resin into the tows (a flaw in this joiner could start a crack and ultimately a failure.)

When the required thickness was reached in this case 15mm and several more tows, I fitted the trunking lid back on working down the tows with a piece of mylar as it was closed. This allows for a more accurate square shape.

It popped out the mould perfectly and has a smooth accurate finish.

This whole process was repeated again so as to have two smooth accurate outer surfaces, the inner face(surface not in the mould) will be machined with a router and bonded together with black epoxy glue and clamped to the correct tolerance.
The final steps and some fuselage work will be in a future post.

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Monday, October 29, 2007

Roberts' Shongololo #7 Maidened

One very happy Robert Davies is now the 5th owner of a Shongololo from the building group to maiden his glider. Remember, his is the one with clear coat on the wings so you can see the hybrid cloth.

As per normal, a check to see that all was set up correctly and moving the correct distance and in the right direction and it was onto the winch for the first flight.

And as per normal she flew like an angle.

As they say, a picture tells a thousand words! How's that smile?

Sunday, October 28, 2007

Great Weather for RES/100

After all the rain we have had over the last few days Sunday turned out to be a fantastic day. An early morning visit to the weather bureau web site produced two spot graph maps of Sundays weather (Click on the image to see a larger version). The one on the left is for Gauteng --- Fantastic!!!! - "Should be a pretty good day for the RES/100 Challenge" I thought.

But just look at the lovely weather Cape Town has in the graph on the right. Warm, light winds, dry and even Thermals. I hope they make an effort. I would be nice if we also get some score from the Cape. Or I wonder what excuse they will come up with as to why they couldn't fly? This type of event is perfect for them and we haven't seen one attempt from them so far this year. Anyway, maybe next year they will try!

I couldn't wait to get to the field and was packed and ready to go at 08h30. Piet was obviously also keen, because when I got to the field he was already there. And it wasn't long before the rest of the mob started arriving. We had a great turnout, with at one stage 14 cars and a whole variety of models and people.

There were only four that participated in the RES/100 Challenge in the end, with Trevor, Wes, Rudi and Tony electing not to fly because of problems with their equipment or models. Piet once again flew his trusty 2,5 met RES iTsotsi 100 , Mike had his OD 3 met RES model and Peter and Evan with standard 2 meter RES Tsotsi's.
We couldn't get Mike to stop flying, he was having soo much fun. So we stood next to him for the photo shoot while he flew .

Mike achieved 2073, just 47 points short of max, followed by Peter on 2055, just 65 point shy, then Piet on 2039,with 81 point missing and Evan, 1964. The best 8 flights for the Club totaled 4194 out of a possible 4240. As can be seen by the scores, it was a very good day for thermals and our lads certainly made the most of it. Well done.

Further analysis of the four flights used for the pilots score, reveals that Mike lost 20 points on landings with his flights being close to max. The worst was 11 seconds short, with a total of 17 seconds short.
Peter only lost 5 points on landings, but a whole minute on flying.
Piet lost 55 points on landings, but would have done a whole lot better if he hadn't hit his helper on one of them, loosing a possible 50 points. Two flights, 9 seconds short and once, 6 seconds and once 2 seconds short. Total of 26 second short.
Evan, lost nothing on the landings, but screwed up one flight. Only achieving 5 minutes 33 seconds. A whopping 147 second lost. Otherwise all his other flights were very good with the worst being 6 seconds short and the other two within 2 seconds.
How to get a good landing. Eish,these Tsotsi's are strong.

This has moved BERG to the top of the rankings again and there we shall stay, as no other club can accumulate enough points to beat us. But the individual positions are still open and until we get the results from the other clubs we shan't know who will be the "Wit Willim" champion.

So, watch this space!

Thursday, October 25, 2007

RES/100 Challenge

A bunch of happy RES Pilots

This weekend is the final RES/100 Challenge for the year.

So lets all bring our gliders along on Sunday and really put in a a good showing from the BERG Club.

The field is in great condition and lately there has been plenty of good thermal activity.

Remember this comp is ideal for the old gas bag models. Any size glider with Rudder. Elevator and Spoilers for control. (Of course, you don't need spoilers but they do help. However, if you don't have spoilers, the landing task has been made a little easier for you.) Full house ships that are not bigger than 100 inch (2540mm) span may also participate. So if you have a glider that is under 100'' and has ailerons and flaps, bring it along as well. The Rules are in the September issue of SAMAA News. Or Tag your email address on the Tag Board and I'll send you a copy. (Of the rules. That is!)

Olympic ............................................................Bird of Time

Spirit ...........................................................................AVA

Grand Esprit ........................................................Viking

Legionaire .................................................Sailair

Even a Tsotsi ...............................................and a Windfree

Fred, launching his Sagitta at last years Nats

Simple rules:

Your best 4 flights from 6 attempts, of 8 minutes duration and spot landings.

It will not be a formal comp, but rather just fly when it suits you.

As usual, there will be two club winches available all day on the Sunday and lots of helpers.

Anyone is welcome to join us for a day of fun in the sun!

Who will be the "Wit Willem" Champion? Will it be Piet or will Paul be able to pull back those vital points and get back to the top?

See you Sunday>

The DMAC gang.
Fred was there with his new "Egg Beater", which is the largest "full house"plane allowed. Peter Plint and his beautiful moulded Sagitta ARF, Dennis dusted the cobwebs off the Eliminator. John C and Brad flew their MiniGraphites, Dave Denley, Don Slatter and Brian Fanning flew SpiritElites, John Wright flew his Spagitta 600 and Allan flew a standard Spirit 2 m.

These DMAC pilots have already put in round 3 scores. (Rounds flown in brackets)

There has been a change to the landing bonus system so please use the score sheets as per the September SAMAA News for this round.

It's really encouraging to see the number of pilots has grown to 29 pilots already. This bodes well for next year and proves that this class is still alive and kicking. I think all the bugs have been ironed out and the rules will remain as they are now for next year. Any comments or suggestions are welcome.

Leader board at the moment.

1 Fred Whitstock 4934 (3 rounds)
2 Dennis Bird 4558 (3 rounds)
3 Piet Rheeders 4223 (2 rounds)
4 Paul Carnell 4182 (2 rounds)
5 Gert Nieuwoudt 3630 (2 rounds)
6 Malcolm Siebert 2975 (2 rounds)
7 Izak Theron 2406 (2 rounds)
8 Evan Shaw 2083 (1 rounds)
9 Mike May 2009 (1 rounds)
10 Alan Sneedon 1990 (1 rounds)
11 John Coulson 1885 (1 rounds)
12 Peter Eagle 1874 (1 rounds)
13 Tony Roberts 1836 (1 rounds)
14 Craig Barker 1830 (1 rounds)
15 Brian Fanning 1830 (1 rounds)
16 Rudi King 1828 (1 rounds)
17 Charl Marais 1767 (1 rounds)
18 Simon Nelson 1691 (1 rounds)
19 Brad Conlon 1608 (1 rounds)
20 Sean Oellermann 1560 (1 rounds)
21 Gordon Prahm 1535 (1 rounds)
22 Johann Snyman 1385 (1 rounds)
23 John Wright 1319 (1 rounds)
24 Volney Klintworth 1315 (1 rounds)
25 Dave Denley 1309 (1 rounds)
26 Don Slatter 1285 (1 rounds)
27 Chris Mc Neil 883 (1 rounds)
28 Andrew Plint 753 (1 rounds)
29 Peter Plint 456 (1 rounds)


1 DMAC 11986 (3 rounds)
2 BERG 8758 (2 rounds)
3 ETB 8490 (2 rounds)
4 TRMC 6782 (2 rounds)
5 SGC 3205 (1 rounds)
6 GGGC 2975 (2 rounds)

I hope we see some entries for SSC, and some other clubs down at the coast this round! We've missed the competition guys!

Wednesday, October 24, 2007


Just had to post this , first coat of 2k on the canopy of the DG500 real cool finish.

Second coat ,done exactly as the first ...disaster, crackle finish, dont know why ,it has to be bad
karma. Remedy is to sand down and start again.

Monday, October 22, 2007


To all the JARTISTS out there including Glen who has a sensitive side and flies a pinkish epp jart(check out the springfield gliders blog). Only kidding you Glen, later this week it is back to JART building, final polishing and splitter board preparation ,as well as moulding ,will be posted.
I am not sure what has happened to Piets Jart and Evans Jart and Lionals Jart and Roberts Jart and Gerts Jart and so on and so on .I know Reed the designer ,has mentioned on Rc groups that many plans have recently been requested from South Africa.

F3B at BERG and Shongololo #8 Maiden flight.

BERG hosted the first of the F3B League events on Sunday 21st October.

This was Round Zero in preparation for next years League and also for pilots to be given a handicap. Check out the F3B Blog for more details and results.

The BERG field is in superb condition and looking really good after the rains. Once again our club did a great job at providing lots of help and assistance. Marti was of course there with her travelling diner and there was plenty to eat and drink.

Preparing to fly

Pits and car park


A huge thanks must go to all you guys and girls for the time you put in to make these events work.

F3B takes a lots of manpower to get it to work properly and sitting out a base B for ages is a thankless job. THANKS YOU GUYS!

Base B Helpers

The flight line

View from Base B

Not to be forgotten! Len Thomas flew his Shongololo #8 for the first time this weekend. Not only did it maiden, but he also entered the event and flew it in it's first event. Ending in first place in the B League, in your first ever F3B competition is no mean feat Len! All these firsts is maybe an omen that you will be the new force to be reckoned with! Well done Len!.

Len with his brand new Shongololo

Friday, October 19, 2007

DG 500 project

In the post below one can see progress on this build , but looking at the hits on the BERG blog several overseas viewers search on the glider type ,which has changed twice so I wish to make an explaination for these as follows

The DG 1000 caught my eye and I decided to build a large stand-off scale model of this glider, as I researched it ,I discovered the DG 505, which has more or less the same fuselage but not such an advanced wing planform.
The DG1000 has a multi taper schumann type wing with forward sweep and lifted wing tip panels with winglets.
This type of wing shape would be more difficult to build and keep the joiner on the centre of lift and would require complex vacumn bagging of several panels.
The DG 505 Orion has a more conventional wing with a straight leading edge and small forward sweep only on the outer panels trailing edge and may also sport winglets , so it may be easier to build.
Then there is the DG500 ELAN with the simplest wing planform , but we are going back through the types here. The wing is where the performance has been enhanced with research.

So why has this aircraft changed its name a few times..well after some initial wing layups I will finally decide how complex a wing I can safely build in the 8-10mtr size with UD carbon cloth
over white foam and it will finally become a DG ???
But for now it looks like a 500 is a safe bet.
Clear as mud.


The work has re-commenced on the GBOGH DG 500 fuselage ,there has been lots of dusty sanding work , but ultimately these efforts are rewarded with quality finishes later on.

The polyester spray filler has nearly all been sanded off ,the high spots are just smooth glass and can be seen clearly.

I have layed down three fairly thick coats of white 2k these will be sanded down with 600 grit water paper after all the additional fuselage work is complete and then sprayed with final coats including coloured stripes . Using a string to mark the centre line as a reference I have marked out the canopy ,this I did with a white board marker so it could be redrawn until it looked right.

I dont have plans and as this glider is only scale-ish I used some good colour photos as a referance.

Once the canopy was cut out using a thin fibre wheel on a DREMEL tool It popped of no problem showing the waxed packaging tape layer
The layers of glass are nice and strong and I will re-inforce the sides of the canopy opening with carbon and a servo tray.

The expanded polystyerene is cut out in chunks,
try do this over a plastic sheet out of the wind, otherwise you'll think its been snowing.
Eventually you just pull the remaining packaging tape out , the finish is fairly smooth and shiney and will need to be roughed up in areas where re-inforcing needs to be attached (in this case some serious carbon tows down the sides).

The foam only extended back to the trailing edge of the wing thereafter the boom is a rolled tube of card type paper , with a stronger cardboard in its centre for support this is re-leased by pushing a rod or dowel stick down the sides to collapse it inwards , and then pulled out .

There you have it the collapsed tube , the support tube , still bonded to the foam pod (notice the spacer I used halfway down to centralise everything).
This is a clean way to build a big fuselage no fuss and no melting out the foam with a solvent and all the goo that is left behind. The melting out of the foam is the way to go if it is a small or difficult shaped fuselage.
At this point a milestone has been reached and
the next steps are the canopy seat , servo tray,
wing joiner tube and rod and decission on how to control the tail feathers sooo far away.
The Go Big Or Go Home philosophy is still on track ,here is the proof ...................oh by the way the little electric 3d that sidetracked me recently, did fly three times,then the motor emmitted a cloud of the deadly smelly blue/white smoke and that was that , this was on the day that the bad Karma gripped the BERG field .. undaunted I have replaced the Brushless motor with an upgraded AXI motor all part of the learning curve I guess, hope to try again soon, depending on the moon phase and the karma availability.
Cheers for now

Wednesday, October 17, 2007

Brits Gliding Day (Preview)

I hope that all the BERG members has received the e-mail that I send out yesterday with the invitation from Chris Adrian to fly in a real glider.

Well it looks like one of our BERG members Jason Edwards was lucky and got to go up at the Brits gliding club for his birth day. He send me this E-mail and pictures this morning.

So now you have an idea what you will be in for on the 17th Nov.
Thanks for the info Jason.



Nerves of steel - Maybe not!
Back on mother earth
" Hi,
This is definitely a worthwhile experience!! - I went for a flip at the Brits
Gliding club recently for my birthday and it was an unforgettable
Attached some pics if you are interested.

Kind Regards
Jason. "