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Posted by Phaedra | Oct 04, 2015 @ 03:10 AM | 2,147 Views
Topmodel Ka8 3m (1 min 8 sec)

About a year ago, I bought a second-hand Ka8 model in Germany. In a previous blog entry of mine I already stated my doubts whether it had really flown as the previous owner claims.
And so I removed about 200g of lead from the nose to get the CG right, struggled to get a towhook installed next to the motor, and I went about maidening this beautiful model.
Performance wasn't exactly what the previous owner described to me.
On 4S with a 13x6 prop, this thing should rocket skywards. But all it did was climb steadily at an acceptable rate.
And then, from the second flight on, a problem developed. Whenever I opened the throttle more than half, the model started howling with a sound that best can be described as a howling cow, or the horn of a freight train.
The loss of power was so sudden that the model stalled several times during initial climb.
I thought I found the culprit when I discovered that the motor firewall had come loose on one side, but after fixing that, the problem still persisted.
So, last week, I decided to dig into this problem, and did some research.
Apparently there are two versions of this model: 3m and 3m20 of span. And I have the 3m version, which has a recommended 35mm motor, with a 14x8 prop, on 3S.
But I got a 4S battery with this model! And so I measured the motor, and sure enough, it's a 35mm one....which I tried to operate on 4S. A miracle that this motor even survived this treatment.

And so I...Continue Reading
Posted by Phaedra | Sep 25, 2015 @ 05:20 AM | 1,380 Views
It has taken a while (a rather shabby flying season coming inbetween), but I'm back at the Marchetti.
The last straws before covering took ages! It's the finishing that takes up all the time, getting all the pits and the wrinkles out.
So first up was to add some sort of smoother transition between wing and fuselage at the bottom. The standard kit leaves you with this:

Not really pretty....
And so I started by glueing on some lightweight and soft balsa:

And since it was soft balsa, it was fairly easy to shape and sand:

...Continue Reading
Posted by Phaedra | Aug 31, 2015 @ 10:38 AM | 1,913 Views
I happened to witness this at the Genk - Zwartberg airfield last Saturday:

T28 landing and taxi in (1 min 58 sec)

Posted by Phaedra | Aug 18, 2015 @ 02:44 PM | 1,615 Views
After a pretty shabby flying season so far, weather contiuously being too hot, or too much wind, or having to work on those rare days when the weather does cooperate, I spent more time building models than flying them. Oh well…
And so I picked up the Marchetti again, much sooner than anticipated (I was thinking rather in terms of "next winter"…). I want to get my woodworking skills up, and this is a very good opportunity to do just that.
Where to start, or should I say resume….?
Well, first thing to tackle are the wing-fuselage fairings. I already did one side the last time, so now I need to do the other side too.
This is how it looks when you build the model according to the manual: nasty:

And so I start by cutting out a piece of very soft and light balsa, in which I make a cutout for the wing leading edge:

...Continue Reading
Posted by Phaedra | Jun 15, 2015 @ 02:53 PM | 2,229 Views
After a long break, I picked up the work on the ASW22 wings again. Lots of things came inbetween, but now that the weather is finally changing for the better I really want to fly this beautiful bird again soon.
Extending the ailerons presents a special challenge mainly because it wasn't designed to do this.
One big problem I encountered was about the steel rond-and-tube to allow the wingtips to be removable. They are very close to the trailing edge, and thus leaving almost no space for hinges.
Second big problem is the thinness of the aileron near the wingtip. Inserting a hinge always causes a bulge on the aileron. When I try to take out a bit more wood from the hole for the hinge, the knife comes right through.
I did cut out all holes for all hinges, but then I was faced with the problem that I just couldn't get an even gap across the length of the ailerons.
So after a lot of trial and error, I decided to change the strategy, leave the plastic hinges out, and use a combination of fiberglass cloth and PU varnish for hinging.

I applied the fiberglass and varnish on both sides of the ailerons, and then applied Oracover for finish.

I had to give up the plan to keep the wingtips removable, because that would mean I would have to make the aileron in two pieces that can slide into each other. But the aileron is so flimsy at the wingtip that this would make it too weak, especially with the torsional forces in mind.
And so I took the easier and more sensible...Continue Reading
Posted by Phaedra | Apr 19, 2015 @ 01:48 PM | 2,664 Views
Last weekend I did the last details to get my trailer ready for the new flying season.
I installed my modular model rack, made from PVC tubes and isolation foam inside, containing my Hurricane, Spitfire and Mosquito.
It leaves plenty of room for another rack next to it.
And then it was time to fix some rack rails to the walls, so that I can insert supports wherever I need them.
On the pics you can see that I used those to securely stow my 3m Ka8 glider and its wings above the model rack.
Pretty happy with this result, now it's time to use it and find ways to still improve its versatility. I need a safe way to add another couple of gliders and the wings of my Twin Otter, which are hard to transport because of the three-blade props.
Posted by Phaedra | Mar 17, 2015 @ 04:06 PM | 3,398 Views
The new outdoor flying season approaching fast, it is time to set some priorities on the maintenance and building activities.
At the end of the previous season I made an extensive list of those, and it turned out to be a multi-page document! But since there's more to life than RC models, I barely got anything of that list done last winter. Most of my time was spent on two new models (Ka8 glider and Hangar 9 Twin Otter) and the continued build of my SF260 model.
So now it's time to prepare some models for the new season, and very high in my priorities sits the ASW22BE 4m glider that I gave a midlife update of motor and electronics more than a year ago. I re-maidened it after almost 20 years of sitting idle, and last summer it flew like never before. Details of its resurrection can be found in previous blog entries.
The upgrade made it lose some weight, and at 3,5 kg at 4m span the low-speed characteristics surely improved.
But one thing I didn't like was the lack of decent roll control. When turning final once I had to apply full stick deflection to counter some crosswind influence
And so, thanks to some tips of one of our senior instructors and experienced model glider pilot, I got the idea to extend the ailerons.
The problem here is that the wings have slide-on extensions, and the ailerons need to be extended up to almost the wing tips to be more effective. So I need a way to split each aileron into two pieces with also a slide-on capability.

But first things...Continue Reading
Posted by Phaedra | Mar 02, 2015 @ 02:21 PM | 2,906 Views
With the models constantly getting bigger, it is getting harder to assemble them inside the house. And so I needed to think of a creative solution to make this process easier.
My latest acquisition, the Hangar 9 Twin Otter, poses an even bigger challenge: to mount the wings, the model needs to be upside-down in order to get the strut retaining bolts in. When I put the fuselage on my Robart stand however, the vertical stabilizer is so tall that touches the table surface, pushing the model up from the stand.
On the field, this would quickly become an ever bigger problem, so I really needed a solution.
So it was time to get out the drainage pipes again, and start puzzling.
It needed to be foldable, adjustable, and I prefer the model to be at a more practical height, so I don't need to bend much to work on the model.
I started from the concept of a foldable ironing board, which gave me the idea of height adjustment by more or less folding.
Above the hinge point, you get a wedge form, allowing a variable fit for any model.
The next problem to tackle, was how to fix the position of the stand, while still retaining the foldability.
I decided on a small plywood platform, on which I attached some clamps that clip over the horizontal tubes. Which comes in very handy as a place to put my transmitter while working on the model! When folding the stand, I can just unclip the platform/tray very easily and stow everything in the car.

The first prototype can be seen in the pics below, and mounting my 3m Ka8 on it showed a shortcoming: I still need a way to support the wing(s) while assembling.
I'm also thinking about integrating a CG balancer function, making it easy to check the balance before every flight. If I make wing supports, I might provide vertical holes in them that can take for instance a pencil, with the eraser part up, on which I could support the wing to determine CG.
Posted by Phaedra | Feb 15, 2015 @ 08:05 AM | 3,551 Views
I took a bit of a break in building this model, mainly because I bought (yet) another one (a Hangar 9 Twin Otter), and I wanted that one ready for maiden asap.
So while I'm waiting for parts on that one, it was time to get my attention back to the Marchetti, and finish the wings, so they can be covered soon.
First thing to tackle was the remainder of the planking around the wheels and retracts. Since that involves quite a complex shape, I decided to first make a template in thicker paper, just to get the shape straight before I start cutting balsa.
Nonetheless, the first balsa part I cut was wrong...made a stupid mistake.....too short....
But the second time, I got it right.
Before I could apply the planking, I had to sort out the problem with the wing retaining bolts. The manual (as usual) says nothing at all about this, and so it was up to the builders imagination and common sense to determine how this should be done.
First of all, just drilling holes through the planking just wasn't going to be strong enough, so I decided to glue a piece of balsa in-between both layers of planking.
I then drilled the hole from the top (where the blind nuts are in the fuselage) straight through the wing.
Then I had to think about the wire routing for the servos, to keep the possibility open to replace any servo without having to remove the planking. I decided to keep the female connectors within reach from the open wheel wells and from the flaps servo hatch on top.
I then...Continue Reading
Posted by Phaedra | Jan 18, 2015 @ 01:24 PM | 3,241 Views
Sooner or later, the less sexy work of installing servos and control horns can not be postponed anymore. Took a deep breath, and just started cutting, sawing and glueing mindlessly.
The kit provided some thin plywood "guides" that fit into cutouts in the ribs Onto these guides, the plywood frames and hatches need to bee glued and screwed.
Since I decided to install flaps on this model, I already had to extend these guides across three ribs, instead of two.
I found the original frame around the servo hatches to be too flimsy, so I decided to cut some covers in 1,5mm plywood, in which I cut out the space for the servo hatches.
I decided to use some servo installation screws to attach the hatches to the guides, on which I glued some dense balsa blocks to receive the screws in.
I cut some other dense balsa blocks on which I will attach the servos, and this assembly will be glued to the bottom of the servo hatches.
While some glue was setting? i worked a bit on the cockpit floor and the canopy.
I cut some 1mm plywood to the size of the cockpit floor, on which I will glue some balsa at the edge, on which I will glue the canopy.
I already rough-cut the canopy for a trial fit, and after I glued the canopy to the floor, I will fine-cut it, and finish it with a white trim.

So, not much to show after a lot of boring work, but even that needs to be done sooner or later....Continue Reading
Posted by Phaedra | Jan 16, 2015 @ 10:17 AM | 4,316 Views
To get a break from the balsa works, I decided to work on my model rack.
I will allow me to stack my models while I transport them in my trailer, and will double as model stands when I'm at the field.
I saw the idea here and there, so I wanted to make my own concept, using drainage pipes.
I went to the local hardware store to get me some plastic 32mm pipes and a whole box full of T-joints. It made me look like some hardcore Lego or Knexx fan...
In one of my previous blog entries I showed some pics of my new trailer that will serve as a mobile hangar. I already started experimenting with some fixed racks inside the trailer, but then I discovered it would require a too cumbersome to fix the models in place.
So I got some ideas left and right, and started experimenting with a removable rack built out of drainage pipes, which can be partially disassembled into separate model stands for each model.
The pictures show the first concept already. It took some figuring out why the rack was always so crooked at first, but then I found out that:
1) the T-joints are not 90°, but rather 87°
2) and they are asymmetric: there is one short and one longer side, and obviously, I had swapped them around for each layer
So now everything looks straighter, and I will be adding some side-supports to keep the rack centered inside my trainer. Instead of using the 87° corner pieces, I will also use T-joints and point some tubes outward too, to fit it exactly inside the trailer.
The...Continue Reading
Posted by Phaedra | Jan 14, 2015 @ 03:27 PM | 3,542 Views
After all the cutting and the sanding on the fuselage, I just had to let the dust settle for a bit. Literally.
So I diverted my attention to the wings, and more specifically the retracts.
I started by connecting a metal gear servo to the mechanical retracts. Only to be surprised by the amount of friction in them. It took so much force to move them that the steel wire I used just bent. Hmm. This is clearly not good. I don't know where the friction came from; maybe it was from the heat of grinding the struts, melting the plastic guides?
So I started looking for some alternatives, but finding metal retracts of this size seems impossible. Considering the cost of buying another set of plastic retracts and the risk of running into the same problems, I compared different options, including making my own metal units.
But while gathering some leftover material from defective retracts, I had another look at the Eflite units I bought for this model.
I then saw the modifications I did to them more than a year ago, trying to fit the struts as close to the retracts body as possible.
That's when I suddenly realized that this was almost the solution I needed.
I made the retract go the other way, just by drilling a new hole in the trunnion, so that the gear extended position was now the retracted position, the strut hole being shifted 90 degrees.
I just had to open the cutout in the retract housing a bit more, so that the struts can enter inside the housing when the gear is retracted.
Then I only had to made some more openings in the wing ribs to accommodate the retract unit in the new position and orientation, and then I was finally able to install it into the wing. First tests show this to work perfectly.
I feel like I finally cracked the retracts code on this model!
Now I can install the flaps and ailerons servos and start testing, before I finish planking the wings.
Posted by Phaedra | Jan 11, 2015 @ 10:25 AM | 3,558 Views
And the saga continues....cut-glue-sand-repeat. The joys of balsa building
Luckily I went over to the LHS to get me some balsa, otherwise I don't know where I would have needed to get the required wood for all the planking I have been doing lately.
As it stands now, the top of the nose is finished, I added the necessary balsa to the aft fuselage bottom, and planked the top.
That was the easy part.
But then the time came to construct the tail around the horizontal and vertical stab. According to the manual, you had to first insert a "dummy" of the stabs, so that you can glue and sand the balsa inserts around it. Easy enough
First challenge was to place the dummy inserts in the correct place and orientation.
When glueing in the 6mm balsa pieces around it, care had to be taken not to glue it to the dummy inserts, or it could ruin the rest of your day.
Layer after layer, I cut and glued the balsa pieces, and while the glue set, I started on the bottom of the nose, with some more cutting, glueing and sanding of 6mm balsa pieces.
The advantages of having some decent and sharp tools around can not be underestimated in this.
A couple more evenings like this, and I can start thinking about installing some electronics, and see some surfaces moving!
But before I can do that, I think I might need to do some cleaning of my workspace......Continue Reading
Posted by Phaedra | Jan 09, 2015 @ 03:30 PM | 3,744 Views
I'm loving this build more and more every day. Working with balsa is so much more fun than foam.
The Jamara kit is really a good and beautiful one, but the manual is a disaster. It contains a number of build pictures, but you are really left to guess which piece of balsa is used for what. It drove me nuts for a while, but then I decided today to pass at my LHS and get me some extra balsa, so I can continue the build at my own discretion and insight.
I'm considering this build as a dress rehearsal for other balsa builds, so now I have the opportunity to make my own choices and see how it works out on a lasercut kit.
First thing I noticed was that the manual suggested to plank the back of the fuselage without ever mentioning the fact that the control rod sleeves need to be routed through this part of the fuselage. That would become quite a challenge after the planking....
So I started with installing the servos for elevator and rudder.
While dry-fitting the horizontal stabiliser and elevator, it dawned on me that I need to split the elevator in two parts eventually, otherwise it cannot move down. So I decided to route two control rods, one for each halve.
The plywood arc at the back of the cockpit area consists of two halves, which have to be glued together back-to-back, so I decided to glue a small piece of ply to enlarge the glue surface, before glueing the whole onto the fuselage.
Then it was time to start planking the nose. Some 1mm balsa was supplied for that,...Continue Reading
Posted by Phaedra | Jan 06, 2015 @ 02:50 PM | 3,303 Views
A grueling work schedule kept me from advancing much on the Marchetti, but I still manage to work on it for an hour or so in the evening, just to keep my sanity intact...
The things that kept me from finishing this model last winter were mainly a lot of open questions about the landing gear, and I didn't get around to find a decent solution then.
Thanks to the mechanical retracts, things started moving again, and so I adapted the main retracts and struts, like I described in the previous blog post.
Since then, I repeated the actions on the other wing, and did some more sanding on the trailing edge of the wings. Still a lot of sanding to do...

Then it was time to focus on the nose gear. For that one I can still use the Eflite retract, which also contains a nose wheel steering mechanism.
To get the nose gear to appear longer, like in the real aircraft, I mounted the retract on a soft wooden platform.
For the nose wheel steering, I added a metal gear servo (I expect the nose gear to take some hits during takeoff and landing), and mounted it behind the motor, as close to the retract as possible, and still accessible perfectly behind the removable engine cowling.
I just hope that it doesn't interfere with the flight battery, since it protrudes inside the space that is foreseen therefore.

I then did a dry fitting of the wings to the fuselage, to get a first impression of how everything looks when on its feet (wheels). And it looks good, I must admit.
It's still a bit high compared to the original, but the body attitude comes really close!
Now that this has been tackled, I can start with some planking and covering....
I already tried cutting the tip tanks plastic pieces, but I'm not at all happy with the result. The pieces just don't fit together. Don't know what I'll do with that.
Posted by Phaedra | Dec 31, 2014 @ 12:47 PM | 3,806 Views
After quite a long pause in its build I decided to pick up the small Marchetti again.
Earlier this year I was able to get hold of a larger second hand kit of the Marchetti, so that left me in doubt about what to do with this smaller model.
Last winter, I got a bit stuck on the details.
Main problem was the landing gear. I wanted to fit retracts in this model, so I bought me some Eflite 10-15 electric retracts.
But soon enough it dawned on me that I could never fit those in.
When you look at the picture of the original (Sabena training school), you can see how low the main wheels sit under the wing, while the nose wheel strut is a lot longer.
In a previous blog entry I showed some pictures of the physical constraints; in short: with the Eflite retracts I can never get the main gear to be that short, and thus the nose gear would have to be so long that it would look like some sort of flamingo.
And so I let this one rest for a while.
When I got the larger model, I started doubting on whether or not to finish this one, and if so, whether or not to include retracts and flaps.
Flaps, I could easily do without. But to launch this model without wheels could pose a problem, since it's not really a docile model from the looks of it.
And then there's the landing....belly-landing a covered balsa wing just doesn't look like a good idea to me.
So, since I already got some decals from Callie Graphics, I decided to continue the build.
The first decision was about: retracts or...Continue Reading
Posted by Phaedra | Dec 26, 2014 @ 06:32 AM | 3,302 Views
In the past few days I've been continuing a bit on my Ka8, to get past that feeling that things aren't really advancing....

Yesterday I finally glued in the floor board, after glueing in a couple of wood pieces to protect the towhook control rod against the battery strap. In the process I also put some epoxy on my newest jeans and in my hair, but let's stay on-topic

I thought about and experimented with ideas about putting some lead in front of the firewall, but in the end I decided against it. The risk and trouble about trying to achieve this doesn't weigh up to the small advantage. Which proved to be true a bit later.....

I then cut some strips of lead that I could glue on the inside of the fuselage, as close to the firewall as possible. This already gives a neat advantage compared to the blocks of lead that were glued in lengthwise. This way, I already saved some 150g of lead in front! But to be honest, the original CG with the enormous blocks of lead was too much forward, so moving that aft contributes the most to that weight gain.

So when I tried to re-install the motor after this, I was confronted with a problem: it wouldn't go in!
The problem seemed to be twofold:
- the extra epoxy and plywood around the towhook was in the way
- some epoxy of the above mentioned operation apparently flowed towards the nose and got in the way of the motor shaft...
But after removing all that extra stuff, the motor went in like before....sign of relief...

I...Continue Reading
Posted by Phaedra | Dec 20, 2014 @ 05:57 AM | 2,959 Views
Some progress done on the Ka8b in the last few days.
First up was the towhook servo. I had to glue a couple of sturdy support blocks onto the cockpit floor, to which I could secure the servo with the supplied screws.
Then I had to choose the longest servo arm available, to avoid that the control rod would touch the underside of the cockpit floor. I must remember to install the battery strap properly before I glue the cockpit floor in the fuselage again, taking into account the towhook control rod movement. I guess I'll glue in a couple of support blocks to guide the rod....
After a couple of tests I was happy with the servo movement, no binding, and a solid connect/disconnect position of the towhook.
Next was a bit of work on the wings. I started with the servo wires, by installing some mpx connectors to allow trouble-free wing installation. I alternated male and female on each wing, so I can make no mistakes when plugging them in.
When I started testing the ailerons, I was baffled by what I saw. In the neutral position, the servo arm was already in an extreme position, which caused quite some trouble for the up movement of the aileron. Another argument for the theory that this bird never flew....
Unscrewing the servo arm proved impossible without some extreme surgery on the wing. Removing the servo doesn't look very inviting either, since it is glued in with plenty of epoxy on the balsa wing covering.
So I had to solve this digitally, against my principles....Continue Reading
Posted by Phaedra | Dec 15, 2014 @ 02:34 PM | 3,447 Views
The Ka8b was the first one-seater glider I ever flew, and I spent quite some time seated on the hard wooden plank, listening to the squeaking of the rudder pedals while trying to keep some thermals over France.
So I didn't have to think for a long time when I found this second-hand RC model in pristine condition.
I had to spend half a day in my car to get it in Germany, and the previous owner claims he had some ten flights on it. But "it just wasn't his thing".
I couldn't care less if he flew it, but the really mint, like-new conditions makes me doubt it has ever flown. Not a single micro-scratch on the landing skid, the wheel is like brand new... And the CG marked on the wing is so far forward that I doubt it could actually fly like that.
But heck, it's like brand new, and I could buy it for a very good price, including the motor, ESC and 4S Hacker this was a no-brainer.
Only downside: it didn't have any spoilers installed (another reason to doubt that someone with very limited fixed wing experience has flown it like ten times and landed it without a single scratch).
I'm not sure which brand it actually is. The online shop he bought it from sells the Topmodel version, and when I look at pictures of that model, there are very strong resemblances, but it isn't really the same.
The fuselage is really solid, which makes it the perfect model to do some slope soaring. It has a span of 3m, the wings are a bit see-through covered and partially...Continue Reading
Posted by Phaedra | Dec 07, 2014 @ 01:27 PM | 3,108 Views
Today I finally maidened my Twin otter.
Maiden Twin Otter (1 min 27 sec)

I started by doing a couple of high-speed taxi runs, to get a feel of the controls.
During the second run, the model already took off, and it landed again after I cut the throttle.
I felt confident enough after this short test, so I decided to give it a go. I had to give it a firm pull on the elevator to take off this time, and as soon as it was airborne it felt really harmonic in response to the controls.
Center of gravity was a bit aft during the first few flights, resulting in a bit nervous behavior in pitch.
Another flaw was ground control. Somehow the nose gear has very little authority on the ground, making it almost impossible to make simple turns after landing (unless at very low speed, almost a crawl)

But all in all, this is a winner, very happy with the result.

So the next step will be to improve on nose wheel steering, and finish some more details (painting, cover the landing gear legs,...).