Category Archives: equipment

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.

Elexant ready


Ready for it’s first flight. It’s been a fun experience assembling the model, the quality of the “kit” and the instructions were really good. Now let’s see how it flies! As usual: More pictures here

Hinging with Beli-Zell


I’ve been searching for something other than epoxy to glue pinned hinges with, and I think I found it at last. Beli-Zell, from Adhesions Technics in Germany works brilliantly, it’s strong, and easy to apply. I’ve always thought epoxy was wasteful and difficult to work with. Epoxy is not easy to get it in the hinge slot, and it’s runny until it cures. Most often you have to tape or oil the hinge pins to avoid them getting permanently stuck. It just takes a long time and is difficult to get right with epoxy.

I’ve experimented with Beli-Zell before, using a file to roughen the surface area of the hinges so that the Beli-Zell glue would adhere better. I used normal Beli-Zell, the green tube which is an expanding polyurethane glue. A lot of hingepins got glued stuck, but no hinges came off. Semi-successful at best.


Two types of Beli-Zell: The white one is perfect as a hinge glue

This time I’ve tested both the green (clear/yellow glue) and the orange (white glue) tube. The Beli-Zell white (20 min) tube is simply something completely different. Using Du-Bro pinned hinges, I glued one with each type of Beli-Zell to a balsa trailing edge. The next day, I tried to remove them. I was able to, using great force, to pull the clear Beli-Zell hinge out. Looking at the hinge, I saw the glue had only partially adhered to the surface. White Beli-Zell was another story. It was stuck, and no amount of force would remove it. I cut away the wood to inspect the hinge, only to find that it was totally merged with the wood. A blob of glue from each tube confirmed that the white Beli-Zell is in fact more elastic, In the picture, the white blob is still slightly rubbery, while the clear glue is stiff and brittle. And best of all – the white Beli-Zell does not expand into the hinge pin. It’s just a a tiny bit to thick, so it doesn’t come in contact with the pin at all. What’s more, the tip of the glue tube fits the hinge slot – two licks of glue in the slot, push the hinge in, and wait for it to set – done! No mess, and no working with old knife blades and epoxy. I just hinged the entire Xigris this way using white Beli-Zell, and it was all done in one evening. I’m never going back.

Xigris C1 build


The Xigris, my first 2×2 electric is underway.

Equipment:
– Plettenberg Evo
– Kontronik Jive 100 HV
– Futaba FASST
– 9650 x 2 in stab
– 9154 x 2 ailerons
– BLS154 rudder

Follow the build here

Futaba T8 FGA 2.4 ghz

FutabaT8
With the switch to YS CDi, I needed to get into 2.4 ghz systems in a hurry to be safe from radio interference with the new ignition system. My trusty old MC-22 is possible to convert, but considering the price tag, the Futaba T8 FGA was simply irresistable. I could get a brand new radio system complete with a very decent 2.4 receiver for the same price a conversion of the MC-22 would have cost. That means I can still use the MC-22 and it’s receivers for older models. Being a handheld radio, the T8 is also a sensible choice for indoor flying.

Another big reason for choosing Futaba is that they have a great range of 2.4 receivers at affordable prices. I could not find another system with more suitable receivers for my need. In addition, Futaba is probably the biggest brand and parts and service is available anywhere in the world.

When buying a new 2.4 radio these days I really wanted a native 2.4 radio, something without interchangeable transmitter modules, empty 35Mhz antenna slots and a bulky WIFI-like anteanna sticking out the back. The T8 is beautiful in that respect, being so simple and elegant and infinitely programmable. The sensor touch control thing is reminiscent of an Ipod’s control pad and very easy to operate. It has so many great features it’s really hard to belive when you compare it to similarly priced systems. It even has the possibility to set five different dual rates/Expo for each channels, assignable switches, everything you’d expect from a modern system. The only negative thing I’ve found so far is that flight modes only work in Glider or Heli mode, NOT in motor plane mode. Pretty silly, but when you think about it, they probably just left that out so that plane pilots have a reason to buy the T12 instead, which is more than double the price of this radio. And who needs flight modes with 5 switchable rates, right?

Here’s the RC Universe review of the radio.

Integral CDi conversion

integral_stickers
The Integral is finally ready. The YS 170 is converted to CDi and as soon as the weather is warmer I will run and tune the engine so it’s ready for the next season of P-11. I’m now using Futaba FASST 2.4 GHz to avoid ignition noise so hopefully I’m immune to radio interference. Ignition is controlled using a Turnigy transmitter operated switch which seems very safe and easy to operate.
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Aries and Addiction kit inspection

Carbonfun

Carbonfun


We had a chance to look at Hennings new weapons for the coming season. One Delro Addiction and a Naruke hobby Aries kit were inspected. There was sausages, Carbon fiber and great fun. Pictures

YS 160 damage

160_3
The YS 160 engine failed to run properly so we opened it up. The valve lifter was stuck, _really_ stuck and we found metal shavings had jammed the pump piston. We tried to fix it but never got so far as to test it, when we saw the busted conrod we thought all was lost. Read More »

Backup battery FAIL


The idiot does it again. Although the battery change worked (I bought two just in case) I had a little accident. The battery blew up in my face during soldering so I had to spend a couple of minutes picking plastic bits from my left eye. All the while my safety goggles were hanging from the shelf in front of me. They say there’s one born every minute so I guess I’m not alone. Idiot.