BERG AGM 2009

First notice of BERG AGM (2009)

Hi all BERG members, please note that our annual AGM will take place after this months Posatls competition at the BERG field on Saturday the 28th of FEB 2009.
This should be at round 2pm-4pm in the afternoon.
Agenda will be made available shortly.

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 pietlewis@absamail.co.za
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 position that need nominate or reconfirmed are:
Sectary
Treasurer
and
Safety officer.

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.
BERG.

Diana2 Flight profile

As per Piet's post, yesterday saw the thermal conditions at BERG getting better and better. At about lunch time, I launched the Diana 2 on it's 4th winch launch and decided to join Tony, Charl and Piet who were in very strong lift under a huge cloud which was building directly above the field. I must say when I looked up it was difficult to spot the Tsotsie's at speck height. Charl/Piet flying Charls glider which has flaps, had the flaps fully deployed and yet the plane kept climbing, amazing lift.

My flight was slightly delayed until we got a slight breeze, just to have a bit of airflow over the wings at launch, after gaining some height indicated as the first peak on the graph, I moved around the sky searching for the core of this powerfull thermal. Once it was located I banked into it and fed in some up. The Diana 2 has proved to be an awesome thermal as well as slope ship and very soon the altitude numbers started climbing. Blake was reading off the Eagle Tree Dashboard and we gained 20 to 30 meters on each circle. The time to height was only minutes and topped out at just over 520 mtrs above launch height.

At this height things start getting small but it is my intention to set some altitude records later in the year and with good optics we can go a lot higher. The clear cloudless winter sky may offer better vision for this. The BERG field lies on the one approach for Lanseria and altough the big stuff comes over at about 1000mtrs plus, it is prudent not to hang around at these heights. I deployed the flaps and started a spiral descent. I am really happy with the results. I managed to lose a lot of height in about a minute and yet the speed remained fairly constant throughout the flight and only peaked at a little over 100kmph. On an earlier flight a high speed pass recorded about 180kmph and no flutter on the control surfaces.

At the bottom of the Altitude graph in purple you can see the variations in the speed indicated with the grey line. At this point I dived, pulled up and did a roll followed by a complete stall and recovery, causing the airspeed at one point to go to the zero line.

I was experiencing some loss of signal problems with this variometer system, but downloaded a new revision of software and this seems to have resolved the signal strength and low packet rate problems and its working better than before.



Hopefully when Peter's new tug gets going we will have many more oppurtunities to fly our big gliders. Aerotow will be our "NEXT BIG THING"

Cheers for now
Only 2 months to the Sungazer.
Mike

New Tug for Aero towing big RC Gliders

The Cessna 182 of Peter Karner spans 2.2 meter and with a strong motor upfront will aero-tow big sail-planes from 4 to 6 Meter wing span.

Once again we had some superb summer weather at the Berg field on Sunday.Unfortunately my Emoyeni could not get into the air due to aileron servo problems, but thanks to Tony and Charl ended up flying their Tsotsi’s and therefore did no miss out on the excellent conditions.

Tony's Tsotsi soaring in good lift we had on Sunday.

Tony maiden his Bird of Time, and later Michael arrived, a new member that joined BERG, with his impressive OD electric build glider and Mike few his 4 meter Dianna to 500 meter altitude indicated on his variometer.

Stephan arrived in the late afternoon and as usual had something new to show us,this time on his HLG to help with range problems, he installed 2X 2.4GHz Rx's on the undersides of the wings.

HTL #1 ETB

After Mike’s furiously fast Celstar repair job postings and Michel’s impressive ASW28-18 teaser, it’s time to take a minute to relax, grab a beer and catch up on some HTL happenings.

Sorry this report is a little late but my blogging seems to be running a bit behind due to work commitments and family stuff (also got a kid’s 21st birthday coming up) all getting in the way.


Well, the first leg of the HTL was held on Sunday 18th Jan at ETB. A good idea to move it later into January as it probably resulted in the surprisingly large turnout of 9 teams (three from ETB) with 27 entrants arriving at the field to get their first leg scores in on a perfect highveld summer morning.

The host club had the farmer mow a large patch of grass for us and their organisation was outstanding. A novel concept was introduced where almost every round had a different CD, the task being taken on by one of the ETB members that weren’t flying the round – and even juniors had a go at CDing a round or two. A little confusing at first but they pulled it off well and there were no problems.


Conditions were overcast and wind was non existent to light while setting up. It strengthened for the first two rounds and then swung 180 degrees for a while before settling to light and variable in direction for the rest of the day. Cumulus clouds developed early in the
day and gave us really challenging conditions – thermals tended to be fairly well defined but light and small. We just managed to finish and get packed up before the first rain drops started coming down on us.

Notable for this first leg of the HTL was the large proportion of 2 meter entries and Craig’s request to have a single flight of 10 minutes with a 2 meter model scored for open and normalised against the 6 minute fliers. This allows a 2 meter contestant to fly open and score in both open and 2 meter classes with one flight. Interesting, and may even work.














Open Results were Chris Adrian first, Craig Baker second and Trevor Austen third. BERG team results were Piet in 9th place, me in 10th place, Peter Joffe (Tsotsi not flying well at all) coming in 23rd. Some of our members such as Gordon and Jochen were placed in other teams. But then since the closing of the MMS field and their members flying at the BERG field and Evan moving over to the East Rand, I’ve kind of lost track of who flies for which club. But it really doesn’t matter – when we all get together it always results in a great flying day. In fact, how about the organisers of one of the HTL events throw random entrants together into fun teams - could be interesting?

In the 2 meter class I managed a third with Dion Liebenberg second and Alan Smith first. For the full results and Lionel’s round by round report, pop along to the MGA blog (link on the right hand side panel).

New Project "Igazi"

This is a new Project. Got the wings cut by Craig Baker, very thin profile, 50 cm wingspan. as a wing reinforcing method, due to the thin section, I thought of using 6x2 flat carbon strips. Routed out a small opening (pick 3) then insert the carbon strips vertically (pick 1) and glue in place with Gorilla Glue, the glue remains rubbery and expands slightly while setting, though filling all the gaps neatly. Further I intend using a 55 diam ducted fan assembly pushing approx 1000 gr thrust, +-45000 rpm with a 2100 3s LiPo battery.

New ASW 28-18 from Germany

After a long period, nearly 2 years of waiting, I have received my new ASW 28-18.

Wingspan 6 m
Fuselage in Kevlar
4 piece wings with winglets all carbon
Flaps
Ailerons
Spoiler
Retract wheel
Retract motor with single propeller
Tow coupling for aerotow
in total 13 servos

Celstar Finishing

Saturday was time to line up the wing joiner system, which in essence is two tubes in the wing and a tube bonded into the fuselage. The joiner is a smaller diameter ali tube which slides through and can be removed. It gets its strength from 32 x 60k carbon tows which are wet out and pulled through, the smaller tube is about 14mm dia. This system has worked well on gliders up to 4 mtrs and handles even winch launching (this was tested yesterday at BERG with the Diana 2).

As the wings were rebuilt the new end ribs of ply needed to be bonded on and aligned. The wing roots are nowhere near to parallel with the fuselage sides.















The ply end ribs are cut out and a hole made to fit over the joiner tube, then using balsa and foam wedges, the rib is aligned with the fuselage and tacked in place with Cyano glue. A mix of resin, micro balloons and cotton flox is used to fill the gap and as shown the wings now match perfectly.















The root and tip ends get a layer of thin glass/resin for strength and this will also be sprayed white the rest of the wing l be covered with ORA-COVER in this case.















Some finishing touches such as decals and registration numbers and the canopy white is applied. This plane now requires the tailplane and control surfaces set up as well as cockpit detail and its good to fly again.

Almost done.

PS. Kobus thanks for the offer of commercial canopies but for scratch builders half the fun is learning how to make stuff yourself.

Found at BERG field

We have found a Mini-Receiver 35 MHz Module, with a 35.150 Christal on the BERG field. Would please the Owner Identify such receiver, type, color and markings and we will be glad to return the item to the rightful owner.

Celstar Canopy

The weather and various factors sometimes make it difficult to work on the big pieces, so we then tackle the smaller detail parts that go to make up a scale glider.

The canopy had to be molded and after making a foam/glass plug. I bought some expensive UDI acrylic clear sheet 1mm in thickness for the canopy this cost me R289 per mtr x 600 wide.

Anyway long-story-short our first attempt with Peter and Charl helping to pull this over a plug while I heated with a heat gun failed when the material split just before the final shaping had been reached. Back to the drawing board, and back to my plastic's supplier for some more material. This time I purchased some interlid PVC clear sheet in .5mm thickness and costing R19.40 a mtr x 600. This stuff moulds easily and on the second attempt managed a good quality canopy. Also at this kind of price is easy to make a few and experiment.


The canopy frame is made from some pieces of ply epoxied together on the fuselage for a good fit.












The relacement TV remote came in this packaging and I thought it could be used as an Instrument binnicle for the CELSTAR.











It was duly waxed and a layup of off cuts used to make the shape, it was cut and fitted to the canopy frame which has been beefed up to minimise flex, it has the rounded shape I was after.










It will make a similar replica to the full size instrument binnicle which is rather sparse of instruments.

The canopy tray needs filling, sanding and spraying, then some instrument detail and finally the clear pvc canopy bonded on. The pilot and his seat will be a seperate section fitted into the cockpit.







The wings need sanding and ply root ribs and then a covering of white Oracover.



Cheers for now.

Celstar wings

Here are a couple of photo's of the wing rebuild. The wings are now all sanded and the skins repaired.

A.
The shear web grove is cut out and a 3mm ply shear web cut to size. The wing joiner tube cut out is made and the alu tube test fitted. The cut out in the ply for the tube is for alignment not strength , that comes from the carbon tows. The alu tube is rough sanded to give a rough surface for good adhesion.








B.
A mix of epoxy, micro balloons and cotton glass flox is used to bond in the shear webs, tubes and ply strip fillers. The pair of wings with the joiner are lined up
and clamped on a flat board until cured. As this is a tapered wing this is done upside down which will impart a slight diherdral.








C.
After it has cured the wings are seperated and the top groove sanded out with a dremal, down to the shear web/ply.











D.
The Carbon tows are cut 2 x long to go out past the servo bay (another weak point) 2 x medium and 2 x short 60k, the top and bottom are the same no of carbon tows.











Thats it for now. Filling, sanding, end ribs and recovering next.

Celstar rebuild moving right along

The Celstar fuselage is prepped for spraying and I have masked out and sprayed the blue band and the red pin strip. I found a tin of very old blue 2k from one of my bikes, must be about 15 years old but not hard. I should have mixed some with harderner and done a test first but I dont have the patience, so I sprayed the blue, which did not flash off as expected and I thought I would have a big problem with curing. Fortunately overnight it cured and has a lovely shade of deep blue and gloss finish.



The stripes are masked over and the white 2k sprayed the results are pleasing, next I will recover the rudder with solartex and spray the orange on the fin and rudder, the lettering and registrations have been cut from vinyl and after application the whole fuselage will be sprayed with a high gloss clear coat.

Hard to see where the repair join is.






The red stripe was masked using a plastic tape from a automotive paint shop 5mm wide and can be stretched/curved and leaves a sharp paint edge.

The wording Flying Springboks under the canopy will be replaced with the word Celstar.








The canopy mould is screeded with a micro balloon mix and will be water-papered smooth. No paint until the clear canopies have been formed.

The new servo tray needs to go in but this will only be positioned if the clear canopy comes out ok and I go with a full scale cockpit.

More progress pictures next week.

Celstar Wing Rebuild

I have started stripping and repairing the damaged wings. These wings are made with normal expanded poly-styrene foam cores skinned with an obechi wood sheeting and bonded on with a layer of glass and epoxy resin.















On removing the covering it is clear as to why this wing failed . Under load the wing flexes and in the case of a loop the bottom skin is under tension and the top skin compression. The greatest load in normally found just after the joiner tube and this drops off exponentially with very little load at the tip. Generally when laying up carbon tows as spar caps we try match the loads and would typically lay more tows in the first quarter then in steps less and less tows until the tip. A big change in structure/material strength is normally the place where things break.

This wing failed under stress because the only thing holding the top skin apart/together is polystyrene. I will route out a groove and install a lite ply shear web and a new set of carbon spar caps. A new aluminium joiner tube will be installed, easy as this wing is flat. Also note the wiring was installed in a tube made with drinking straws and this will need to be replaced. I will install a piece of fishing line through this tube as a pull through.

The damaged area is cut out and a new piece of foam glued in with 5 minute epoxy.















A rib template is tacked on and using a hot wire bow the wing core is cut to the original shape. A little sanding and a new piece of balsa skin is epoxied back on and clamped until set.

Both sides and some new leading edge needs to be done, next I will tackle the smaller wrinkles at the tips, sand everything down and cut through the wing for the shear web which will go out about 1 mtr with the joiner tube.





In the meantime the canopy form has has been layed up with 3 layers of 163gr glass and epoxy. As usual the foam was covered with packaging tape to aid easy release.

Thank you. Any questions please feel free to ask.