Topic: Hanno Prettner

F3A Vintage Rosentalpokal 2014

Photo by
Photo by  Karlheinz Gatschnig,

The vintage F3A meet Rosentalpokal is flown using models from around 1975, in Carinthia, Austria. Karlheinz Gatschnig was there and took some wonderful photos.
The event was also covered by FMT magazine and in issue 3/2014 (PDF)
Notice the big Dalotel pictured. It is a prototype of an ARF that will be available from Schweighofer. It exactly replicates Hanno Prettners original Tournament of Champions Dalotel.
See all the photos from Karlheinz Gatschnig here

Supra Fly 25 resurrection

I built an old Supra Fly 25 from the OK model kit in 2002, flew it with an O.S 40 LA, and stored it away when the engine was sold. I came upon a new-in-box O.S 32 SX engine in the summer of 2013, and I put two and two together, literally. What a match! The airframe was still as solid as when it was new after all that time in storage, it just needed a good cleaning. I treated it to some more color on the wings and a dozen stickers to liven it up a bit.

Inside, it got a new CG-mounted fuel tank, a whole lot of stuff removed with the dremel, and new digital servos snugly fitted to a carbon tray. But there was no cowl! I had the old one, but it was A) not original, being taken from a Supra Star, and B) had all the cut outs for the engine and muffler in all the wrong places. I was unsuccessful at moulding a new one and so ordered a Great Planes Escapade 40 cowl. It was too deep and too high but I managed to cut it in half, join it again and shorten it, before repainting it yellow with red trim. It fit perfectly!

An underslung Hatori tuned muffler finished it off nicely, and I look forward to flying my old friend with all new equipment this winter.
This is the way it looked in 2002, and this is what it looks like now.

Curare update

The 2013 contest winning Curare ARF was badly treated. In order to win, I practiced intensely two days before the contest and ignored signs of worn bearings. The engine quit and I landed nose first into tall grass. Broken header, bad bearings, broken nose gear. With no time to spare I managed to patch the cracked header using silicone tubing, screwed the nose gear in the lowered position and tried not to think about the bearings. It held together for 2,5 flights, enough to win my first contest.

Now for the overhaul. A new setup is costly and I decided to retire the engine and buy a new one. A new header was ordered as well. The nose gear was not that easy, I could only buy a trike set and not a single replacement nose gear motor, so to save on my budget I bought a cheap Hobbyking set. I should have known better, they fit poorly and I had to shim the mount to get sufficient height. Anyway, It’s on and it works.

With the removable cowl the overhaul was easy. However I noticed that the firewall had also come loose. All the glue joints were cracked and it is a testament to the build quality, the notches was all that held the engine for three flights, and I never noticed a thing. It was simply a matter of gluing the joints, and there it was – completely overhauled and ready for a new season that I very much look forward to.

Curare wins F3A retro contest

The Curare Trio: Me on the left with my Schweighofer Curare ARF (glow), Ingmar Svensson (middle, third place) with his scratchbuilt Curare, and Ola Maltesson on the right (5th place) with his new Schweighofer electric Curare.

The Swedish/Norwegian border cup is back, and our Swedish neighbours hosted a three day F3A event at Lilla Anrås airfield just outside Fjällbacka on the beautiful Swedish west coast. The event started with an informal retro-F3A meeting on Friday. Designs older than 20 years were allowed to enter the competition. Electrics were allowed, but got a 10 % penalty due to “the silly noise”…

Ola Maltesson getting ready for his third flight, Conny Åquist carries his Curare

The nostalgic event was hosted by Mikael Nabrink, Ingmar Svensson and Conny Åquist. The “Curare Cup Normal” schedule was flown, and it worked well. It’s easy to fly but hard to master, so there’s something in it for everyone.

Ingmar Svenssons immaculate Curare with Webra 61

Three pilots flew Curare. Two were Schweighofer ARFs. Ola Maltesson flew his brand new electric Curare, and former World Championship contestant (1989) Ingmar Svensson flew his immaculate model built from MK plans. He used an old Graupner 6014 radio from the 1980, converted to 2,4 Ghz, and a Webra Speed .61 engine. Truly nostalgic! Ingmar flew the most precise figures, but had fuel tank problems and had to land dead-stick after two short flights. He came in third place following his great third flight.

Ola Maltesson used his new electric Schweighofer Curare to win 5th place

I flew my glow-powered Curare, and it performed well for the first two rounds, despite having undergone hasty repairs to the cowling and having a cracked exhaust header. I also damaged the nose gear two days before, so I had to fly with it locked down (nobody noticed!). In the final round the engine quit with ruined ball bearings, and I had to land dead stick. It was a worthy end to its hard life with full throttle and much Nitromethane – I won the contest and could take home the fabulous Asano wooden prop signed by Hanno Prettner.

First price – Asano propeller signed by Hanno Prettner

More pictures here

Hanno Prettner Curare ARF part 3

The final part of the build is the engine and pipe setup. This is usually time consuming with a lot of alignment, but I found that not to be the case here. One evening, and you’re done!

The firewall and tank area is 100 % ready from the factory, fully fuelproofed. Even the blind nuts for the engine mount is installed. No epoxy has been allowed to ruin the threads either, they have been very carefully covered with tiny pieces of masking tape!

The O.S. .55 AX engine is mounted. (Note the nose gear electric motor protruding through the firewall). Just bolt on the engine mount, and drill holes in it. My only grief here is that I did not find any measurement in the manual regarding distance from firewall to the back of the spinner, so that I could position the engine correctly. Trial-mounting the cowling solves this. By removing the cylinder head (you have to do this later anyway), you can slide the engine in and out with the cowling on to determine the correct position. All hardware for mounting the engine is included, right down to the last washer. The throttle linkage fits in a ready made slot in the tank tray, you just have to drill a hole in the firewall, and the resulting linkage is nice and straight.

The fuel tank comes next. It is included, it’s decent quality, and it fits like a glove. It’s large, and it needs to be -a piped engine burns a lot of fuel. The tank tray is installed, and has cutouts for straps. These are not included, so I used spare helicopter battery velcro straps. Fit some soft rubber sheet under the tank (to prevent foaming) and strap it in place.

The straps are slung around the nose gear cable to hold it firmly in place.

Tuned pipe
The pipe is next. It turns out you can’t buy a decent header/pipe combo at just any hobby shop these days, so you need a specialty supplier. Many experienced modellers might still have suitable headers and pipes in their drawers. The days when Hatori produced 2-stroke headers for just about every plane in production are over, but you can still get hold of a #400-series 2-stroke pipe in certain places. I opted for the so called Purple Pipe combo made and sold by Just Engines in the UK:

This is the contents of the medium size Purple Pipe Combo, that fits 40-50 size engines. For a very reasonable price you get everything you need with a 1-click purchase. The three-baffle tuned pipe, a header, silicone coupler, straps, pressure tap, screws and a pipe mount. You can choose three different widths for the header. The wide header is the best suited for our Curare. While our engine is a .55, you do not need the big 60-pipe. It will be too large for the plane and too long for the engine. And clever readers will notice that Purple pipes are no longer purple in color…

The header is fitted. It clears the nose gear perfectly. I bent it ever so slightly outward by hand (it’s aluminium) to get the radius 100 % correct.

The pipe mount is ready. This is a very simple Dave Brown pipe mount. I shortened it a bit, used the offset mounting option, and it fits beautifully. To secure the mount to the wing, I carefully drilled a hole in the center spar, threaded the hole, saturated it with thin CA, and screwed it in.

Note: Engine trials done after the pictures were taken proved the header to be too long, so I sawed off about 3,5 cm. using a metal saw.

And that’s it! Nothing to it. When the engine and pipe are in, you must Dremel a large opening in the cowling to clear the header, carb, cylinder head and needle valve. It seems brutal to cut out almost a third of the beautifully painted cowl, but when it’s done you can enjoy the sight of the beautiful O.S engine hanging out. It tops off a very nice looking plane.

Weight and equipment used
The ready to fly weight of just 2.93 kg for my model is nothing short of incredible. A decent Curare could weigh in at over 4 kilos in back in the day. The target weight of 3.1 kg is within reach for all builders of this ARF, regardless of equipment used. I built this plane like a would a 2-meter contest model, saving weight whenever possible. For an ARF, that means using glue sparingly, and fitting strong 40-gram digital servos. Using mini servos for flaps and throttle saved further precious grams. I used a Futaba 9650 for the flaps, Futaba S-3151s for ailerons, and Futaba S-3050 and 3172 HV for elevator and rudder respectively. Ideally, I would have used S3050s or even BLS-551’s all over, but I had all these lying around. The electric retracts has an operating voltage of 4,8 – 6 volts, so that excludes the use of HV-equipment. My 2200 mAh NiMH RX battery could be exchanged for a lighter 4-cell 1000 mAh pack, but the CG was spot on with the heavier pack. Higher voltage also means faster servo response and less current draw.

Ready to fly – almost. There’s still all the servo programming to do, and we’ll get to that in part 4 – I’ll show you a few videos of the plane on the workbench, demonstrating undercarriage operation and the different control surface mixing.

Hanno Prettner Curare Part 2

This is part 2 of a field and bench review. In part 1, we installed the main gear, ailerons, and joined the wing halves. When the wing halves are joined, we move on to the flaps. The instructions are different for electric and glow power – for electric power, the flap servo is to be installed in the back half of the wing, presumeably to give space inside the finished fuselage for the battery box. For the glow version, you are instructed to put the flap servo where it fits most naturally, in the center of the wing, using the supplied pre-cut servo mount. It fits all std. size servos, but I modified it slightly to fit a Futaba 9650 mini-servo. The flaps are not big, so you do not need a powerful servo, but centering is important. The linkage is built into the wing, and all you have to do is add the two horns, and cut the supplied pushrods to length.

Why the flaps, you might wonder?
At the Las Vegas TOC in 1976, square manoeuvres were flown for the first time and the corners had to be flown sharp, crisp and tight. So Hanno invented a Flap system which operated with the elevator controls and called it Snap-Flaps. It was THE sensation at the TOC and the year after even more Snap- and square manoeuvres had to be flown, and most of the pilots copied Hanno’s Snap-Flaps. If you want to have fun, just couple the Flaps opposite with Elevator and you can draw square figures in the sky. And the stopping for entering into spin is even quicker. For smooth and rolling manoeuvres the flaps are not engaged.

Finished flap linkage. You’ll notice the mass of servo cables extending from the wing. There are five in total… Even if you fit mechanical retracts you will have four wires to plug into the receiver when assembling the model. I decided to spend an hour soldering an MPX 6-pin plug. Two plugs for +/-, and 4 for the different signal wires. (The main gear only needs a single signal).

Here’s the finished plug – five wires from the wing to the receiver via one 6-pin plug.

That completes the wing!

The fuselage
First thing to add is the nose gear. This is steerable (optional) and linkages are included. After cutting the nose gear leg to proper lenght (specified in millimetres in the manual) you simply screw it in using the supplied screws. If you want, you can leave it fixed by simply tightening the set screws. I chose not to make it steerable. If needed, you can add this later by simply loosening the set screws and hooking up a pushrod to the rudder servo horn.

The nose gear is installed. The nose gear and main gear on my plane are plugged into different channel ports in the receiver, and both are set as “Gear” channel with the same switch.

The fin is an integral part of the fuselage. To complete it, simply glue in the pre-hinged rudder.
The stabs have a negative angle, a central part of the curare design. It means they have to be glued to the fuselage separately with a central joiner, and there is much alignment that the builder must pay attention to. On my model, the fit was perfect, so after removing the covering (you attach the stab and draw a pattern around the base rib to see the area to be removed) I was able to glue both halves in one go using 30 min. Epoxy, and the alignment was much easier than I had anticipated. The stabs are fully sheeted, which makes them strong and light, and the whole assembly could be made removeable if cunning modellers would wish to make make such a modification to their Curare.

The stab root is traced, covering removed, and one carbon guiding pin and a negative angle plywood joiner glued in place after every measurement is checked. Then the stabs are glued in place with Epoxy.

The elevators are then glued in place with thin CA on the hinges, and you are ready to install the pushrods. Once again I differed slightly from the manual and used threaded rod as control horn, and substituted the plastic clevises for metal ones. The rudder has the supplied horn as you can see in this picture:

The rudder was too thin to use the threaded rod control horn technique.

Pushrod guides are pre-installed in the fuselage, but the supplied 1,5 mm pushrods are not threaded so that you have to solder on threads for the links. While they are supplied with the kit, and of good quality, I would have preferred not to have to solder, as this might be intimidating for inexperienced builders. It’s still an understandable compromise. Threaded 2 mm rods would be heavier.

The servo mount is installed the fuselage, but you have to add two spacers that put one servo higher than the other so the servo horns will not interfere. These spacers are supplied. To connect the two elevator pushrods, you are meant to use the supplied 3 mm wheel collars. I differed from the manual here, since I had a spare coupler lying around. It’s the same principle, but it just looks a bit tidier:

Elevator and rudder servo. The coupler can be seen on the right. I’m sorry I don’t know where I got this lovely specialty item from, but you can use wheel collars (supplied), that will work fine.

I used a metal gear digital mini servo from Schweighofers own brand for the throttle, which brings me to the final part of the assembly – the engine, which we’ll deal with in part 3.

Hannos big planes part 3

In the late 1990’s Hanno built and flew the most advanced show plane in the series, the Sensation 2000.

The plane is still kitted by his old friend Yoshioka at Yoshioka Model Factory in Japan.

Shown here at a 5000+ spectator air pageant in Japan, Hanno flew his Sensation with some of his old friends from the F3A scene such as Yoshioka and Naruke.
Also visible are his huge profile Dalotel and an flying downhill skier – all three planes a worthy testament to his dedication to innovation!

Posted by Picasa

Hannos big planes part 2

In the EZ/O.S. engine years of his career Hanno Prettner produced a number of show planes based on his experience with F3A models and the big Supra Fly.

The big Supra Star shown in the picture above was powered by the new O.S. 35cc BG-X engine which was a powerhouse of unprecedented proportions in the 1980’s. Hanno had it coupled to a huge pipe and flew his Supra Star BGX on the show circuit, developing manouvers such as the Hanno Screw.

EZ mass-produced this Supra 3500 ARF shown above and it was within reach of most pilots’ wallets. The plane was a perfect match for the O.S. BG-X and gave everyone the possibility of learning to hot dog “hanno style”.

The mystic was his F3A WC winner in the 1993 comeback following the miserable 5th place in Australia 1991. It was produced by OK model as an ARC kit and as an ARF by EZ. The Mystic BG-X was the “big brother” version and followed the outline of the Supra Star BG-X closely and as you can clearly see it was a sign of things to come, it bears clear resemblance to the ultimate show flyer ever built – his late ’90’s Sensation 2000.

Posted by Picasa

Hannos big planes part 1

While Hanno is primarily known for his performances in F3A back in the days when .60 engines were the rule, he also flew in the TOC (Tournament of Champions) in Las Vegas, winning everything there was to win for years on end. Attempts to alter the rules to allow others to win failed, he kept coming back with a vengeance. Always the tactician, when they introduced new rules offering bonus points to biplanes he brought a Super Skybolt biplane and was disqualified for mysterious reasons when it became obvious it would be another winning year for Hanno.

The most well known of his TOC entries is the giant Dalotel which was powered by two Super Tigre .90 engines connected together using a self-developed gear mechanism. The plane weighed 15 kilos and had enormous thrust, dwarfing glow-powered competitors and flying circles around the chainsaw powered planes.

A big difference between Hanno and many other successful pilots is that he took showflying very seriously and developed planes and manouvers specifically for that purpose. The big super Tigre powered Calypso led the way for the famous 2,06 meter Supra Fly shown here. With 6,5 kilos weight and a piped ST 3000 for power it was a showstopping monster. The plans are available from in Germany and it can easily be modified to fit todays 2-metre/5kg rule and would be a beauty with an O.S 1.60 in the nose.

Posted by Picasa

Those were the days

Hanno with his Curare at the TOC in Vegas, some time in the late ’70’s… Gotta love the carpeting.

Posted by Picasa