Arother Smart Jart hits the BLOG Chart

Not be be outdone, Piet has forged ahead in the JART race and finished his fuselage. When Piet came around to my place to help me with the knuckles on my Shongololo, he brought it along to show me. We dissolved the foam out with petrol and shed around 100grams.Now the other Jarters must play catch-up because I have it under good authority that Piet is already busy with the wings.

Who will be the first to have their Jarts flying???????

Full Size Gliders at Orient

Orient Gliding Club is hosting the (Full Size) Gliding Regional Champs. It finishes on Saturday so if you want to see some really nice full size gliders I would recommend you pop out there tomorrow.
The start is from 12h00 onwards so if you want to see the gliders and lots of action, then get there at around 11h00.

What's really lekker is that you are allowed to walk amongst the gliders, check them from close up and chat to the pilots.

There are about 30 gliders that are participating so lots to see and ooogle at!

Even big scale gliders that you can poke your fingers into.???????

The tasks normally last about 3 to 4 hours so if you hang around until about 16h00 you will see them start coming home again.

Mini-Phoenix Rebuild

Looks like all the regular bloggers have either all gone away for the long weekend or have been too busy in their workshops to write.

I've been very busy finishing off a rebuild of my Mini-Phoenix. So, to keep some variety on the blog I'll write a short story of the history of this little electric model.

Bought from the local hobby shop with a Speed 400 motor, added a Skyborne 35A controller and cheapie 2 cell Lipo, installed the radio, set up some flap/aileron mix and it was flying. Not the greatest flyer with it's silly inboard ailerons but good enough to get in some relaxing late afternoon stick time. But why are we modellers are never happy with a reasonably flying model - wouldn't a little more power just be great? A quick upgrade to a 3 cell Lipo gave a much better climb rate ... but what was that ... could it be a smoke trail? Managed to land very quickly and found the battery pack bloated to about twice it's normal size, one cell burst, a bad chemical smell and everything near the battery very hot! Lucky escape and I went home to clean up and analyze. That little motor could never draw enough to cook that battery, the controller was more than enough for the setup, so what was wrong? Electric gurus on the chat group pointed to the controller not being set for the extra cell, causing the Lipo to go way below it's allowable voltage.

Problem solved but the Natal Nats were two weeks away and it was time to move up a notch and have a bash at a brushless motor setup! Picked up an old Walkera heli inrunner that fitted without any modifications to the mount, had a 10A controller lying around and invested in some good FlightPower 2 cell Lipos. Added a mean little Cam 8x6 prop and blew all the indoor plants away in the lounge bench testing the rig.

Above left: At the Nationals - round 1 and ready to go. Note the determination and confidence on that face. Above right: Great climbout for first and final flight. Climbed to a spec in a few seconds and then ... nothing. No control and straight down she came, filtering throught the pine trees before planting into the hard Natal soil.

Problem was obviously (in hindsight) the little 10A controller. It blew itself to pieces with tiny components and solder splattered all over the inside of the fuselage. Structural damage was not too bad but I was never happy with the design and decided to redesign and rebuild - of course it would have to be balsa open structure and the purple finish!

It has taken a few months but now nearing completion as the following photographs show:

Wing underside now covered - found some lovely deep yellow SolarFilm and mixed it with a bright purple - sure to brighten up the sky on a dull day. Sexy F3J wing and tailplane shape evident.

Decided to go almost full house on the wing moving surfaces. And why not with the small and reasonably priced servos available now? One servo driving both flaps from the centre and a servo for each outboard aileron.

Thoroughly enjoyed building the wing joiner system. Three piece wing has bolt down flat centre section with slight dihedral on plug in tips. Pine dihedral joiners and aileron servo mounted ready for connecting rod and then top wing covering.

T-tail stabiliser with control horn to be concealed in rudder post - still going to be a bit of fiddling to get that lot to work in such a small space. Oh, and adding a moving rudder as well (small servos and all that ...)

Still a bit of work to be done on that fuselage but all burn marks will have to stay. Wing mounting area cut down and refilled to fit new wing section and extra layer of cloth added ouside behind the wing where fractured from the crash.

So far so good. Will post more when finished and ready to fly ...

Is it a bird ? Is it a plane? Is it superman?

No its a JART.........

I had my pdf plans printed out full size and being a patient sort of chap decided only to start the next day, here is the build thread thus far.




I marked out a traced template and glued together some scraps of blue foam , I no longer have big pieces so this will have to do.




Using P/U glue from alcolin I glued the pieces after wiping them with a damp cloth, the P/U glue needs moisture to cure, it tends to foam up and this is great as it fills gaps, once dry I roughly cut to shape with a hot wire bow.

AS usual I work on the floor with basic hand tools , the belt sander if used wisely, sorry that should read gently, sands the blue foam quickly, nice to radius edges.

Here I have started hand sanding with a block and trying to reproduce the Jart shape, they weren't kidding with that PNF pointy nose fetish thing, it looks possitively evil.

It does have an appealing jet shape.....
I have shaped the tail fin and attached it, at this time I have decided to layup some thin cloth/epoxy and filler and finish off to a sparkle before pulling off a mould.

How is yours getting along???? Evan , Piet , Robert and many others whose names escape me, right now.

OLD DOG NEW TRICKS

In the art of model gliding there is always something new to learn and I wish to share some things I learnt recently, they may come in usefull.

On the recent trip to Volksrust some of our pilots remarked that the air seemed to lack power(not sure if this is the right word) plenty of wind, but when it subsided everyone came down.

It was a noticeably smokey and hazy sky ,as opposed to the last trip 3 weeks prior when air was cold(dense) clear and with vapour trials behind the jets.

There are a few theories , some air flows around the slope, some goes over and accelerates , early morning and late afternoon there are local anabatic and catabatic flows(warm air rising from the valley late afternoon and cold air sinking in the mornings).

With the above lesson in mind one also has to factor in thermal activity as the air warms up.

As the above relates to two incedents that occured over the Big 5 weekend let me explain, during a lull in the wind William from Durban launched his scale Discus and all it did was sink, lower and lower, after a while a thermal came through and he climbed back to ridge height, assuming all was now back on track he continued to fly on the slope front and again sank down , the thermal cycle was about 5-6 minutes apart and he had to outland long before the next lift arrives, so slope lift was replaced by thermal cycle lift.

Some time later the wind appeared to have picked up and I prepared to launch the Ventus,

Evan was doing the honours and I instructed him to wait until the wind picked up (air that is rushing in to a thermal that has already gone by). The glider was launched right at this time and fell away narrowly missing the rocks , it just seemed to sink and even when trimmed continued downwards. I decided to fly away from the slope as this was all sink (at this time I was already starting outlanding plans) .

In hindsight this air was being pulled back away from the slope to an oncomming thermal ,I flew in a straight line outwards and at minus 61mtr hit a good thermal , three turns to slope height and four more saw the glider 120 mtrs above the 200mtr radio mast (a total gain of 381 mtrs in 4 minutes) have a look at the data logged .

This flight ended after some high speed passes on the slope front and then a low slow ,again in this sink cycle resulting in a loss of aileron control, the aircraft came down into the scrub next to some picnickers (I should not have flown so close to the slope and they should not have been camped out in the flight line area) as Piet wisely put it 2 x wrongs dont make a right.

A lucky escape and a big lesson, there is a lot to learn about thermalling and slope air currents and some days they are both present take time to study the conditions.

Its a long story but I think it makes sense.

PS I have my own Jart plans, watch this space.

PPS better still why dont you also get some, they're free

Heidelberg Sloping

And now for some not-so-local news from the weekend: Sunday being a lovely warm day with a reasonable wind blowing in from the west, Martie and I decided to visit my sister in Heidelberg and spend an hour or two on the slope on her farm.

The main slope faces south west but I’ve flown in winds varying from south to west. The west corner sometimes works very well – probably due to the deep and narrow ravine just behind that corner.

Total launch point height from the flat fields near the farm house is 70m: 30m slight rise to the base and then 40m of full on steep slope (Google Earth stats). Red spot is the launch ledge and the photo view is from the green spot. BTW – check the very bottom left of the picture: The yellow spot marks the flat field that we propose flying the HTL final on the 2nd December.

But be warned: this is not a slope for sissies! You first have to walk from the farmhouse to the slope, then climb the slope face – and you have to land at the bottom!

The view from the top is lovely, you can see forever
over a big valley scattered with farmland and small dams.

Wind was a little gusty at the top so I opted for my little elliptical model which performed so well at Volksrust last weekend. Big aileron throw gives great manoeuvrability and helps to get out of trouble quickly - but sometimes gets you into trouble just as quickly! I bought this model from Charl Randall who says it’s a Tito but I can’t find any info on the web – anyone out there seen one before and have some info on it for me?

After some great flying with the swallows (very welcome back), all that’s left is to land it down the bottom - watching carefully for the shadow! And then the long trek back to the farm house.

GBAF

Mark Schutter has been itching to fly his scale ASW22 for some time and Sunday was the day.

It is beautifully decked out in Rothmans Livery. (Anyone for a smoke?) Three servos per wing. Two for ailerons and one for flaps. It is also fitted with blade spoilers which are driven from a servo inside the fuselage.

Proud owner, psyching himself up for the big moment.

Complete with pilot. (John Lightfoot would approve)

It's big, very, very beeeg!

Mark had fortunately put two tow hooks either side of the fuselage, high up the side much closer to the wing. This is a good idea with big fuselages when the wing sits near the top of the fuselage. It helps prevent a lever action from pitching the nose upwards when under pull from the winch.

After assembly Evan and I helped him get it ready for the launch. Because of it's size it is impossible to hand launch so the only option was ROG. (Roll off Ground)

Mark had made a "Y" harness which was attached to the end of the winch line and then to the two tow hooks. The line straightened and final checks done.

Myself was on the wingtip and Mark on the foot switch and all was set to go.

In Mark's words ... "Five seconds before the start and you don't want to be here!....

And then!

It's GO! GO! GO!! And suddenly you are all full of excitement. The adrenaline has your heart pounding and you knees knocking and you feel as if you are on top of the world!"

Beautiful launch! Three frames and about 10 meters, it had lift under the wings and it was flying. Straight and true!

.........IT FLIES !.........

After some initial trimming, the nerves settled down a bit and it was soon in a thermal and climbing away. It is amazing how easily these big ships fly and catch thermals. They are just so graceful and really look the part.

After about 30 minutes Mark decided to bring her down. While there was still enough height the breaks were deployed to test them and she slowed down without any pitching. Perfect!

Then the landing!

Fly around and set up for a smooth approach................

.................AND.............

Touchdown

Congratulations Mark!

For those of you wondering what GBAF means.

It's GO BIG AND FLY!