It was one of those incredible warm and sunny august afternoons, with clear blue skies and just a hint of a breeze, and I brought my daughter along and went flying. We were alone at the field when my Killer Kaos crashed spectacularly.
I tuned the engine. At first it was flooded, and that killed the OS #F plug, so I replaced it with an OS #8. At home, I had shortened the pipe by cutting the header a good 2 centimetres. It worked. The engine ran strong, frighteningly so, as I tached it at 11.200 rpm. Glad I ordered bigger props, I thought, as I took off. Immediately it started leaning out, not providing the power the tachometer promised when on the ground, and I landed a minute later. The engine was piping hot, it oozed heat and I scorched my finger touching the head. I was at a loss, and then I remembered:
The engine was bought used, and when I got it, it was full of burned Castor oil. I always use 15% nitro and 15 % Aerosave pure synthetic blend in my engines. Problem is, this engine was brought up on low nitro and Castor oil and it was made in an era long before the AX-series engines I’m used to now. So I switched fuels, draining the tank and putting in 10 % nitro fuel with 18 % synth/Castor blend oil. The difference was amazing.
It screamed. I was able to turn the needle almost one full turn out, and power and smoke just kept coming. Simply unreal. Delighted, I took off into wind, and the Kaos was tooling along the blue skies like a dragster down the strip, a gorgeous white smoke trail in its wake. It just hauled upwards like nothing else mattered, and I got that incredible, indescribable rush of pure joy and I wanted nothing more than to hammer the throttle and roll upwards until the cows came home. Then it blew up.
I knew it was flutter before my brain even processed it. The elevator boomed for a second with such ferocity, it even drowned out the sound of the engine. I startled so that I pulled the throttle back as pure muscle reflex, attempted a turn towards home, and realized only the ailerons worked. It wobbled, stalled and then went in nose first. It only lasted two seconds.
The engine was buried 10 inches in soft soil. The fuselage from the rear wing mount forwards was smashed. The fuel tank, receiver, two servos, battery, everything smashed. One wing half in pieces, another crushed. Incredibly, the header and pipe seem undamaged. But the plane is a total loss.
The elevator fluttered. No doubt about it. There is a gaping hole where the elevator horn was, and the carbon rod broke where the threaded rod was screwed into it. The horn and link is missing. It’s one of the very few planes I’ve had over the years with a single elevator pushrod, and it will be my last.
I’m really sad. I was in heaven, truly enjoying myself and thinking that wow, this is what all those hundreds of hours in the basement is really all about. The sound, the smoke, the goose bumps you get when you pull up and the plane, your creation, just keeps on going. And then nothing but silence and sorrow.
I’m also grateful, now that the shock has passed. Grateful that a lot of expensive parts survived. Grateful that I had those few minutes of pure pleasure in the skies before it was over. Grateful that it landed in a field and did no harm to anyone. Grateful to have had this plane. I always wanted to fly pattern, and this was the first plane I had that didn’t crash. I flew it in its original version for four seasons, and it really taught me to fly pattern. It inspired confidence, and I felt it even today, that my fingers could do nothing wrong with it. It was… solid. A rock.
The only way to relieve my sorrow is to look ahead. My decision was already made as I walked to the crash site: I will build another. It will take a while, as is my custom, but I have already started to plan my next one. I will build it from scratch, I have my original plan, and using bits and pieces of the wreckage as templates I will build a new Killer and fly it like there’s no tomorrow, and as a homage, the new one will carry one single wing rib from the original with it into the skies.
So long my friend.
The O.S engine gave me a little headache. I ran it at home a little bit, and it ran strong and started like any O.S motor should, i.e. with a light flip of the prop. It tached 10.000 rpm on the APC 11×12 and idled smoothly. All was well and then I tried holding the nose up, and it leaned out badly. A lot of tweaking later, I was unable to fix it. I re-did the fuel plumbing and moved the tank a lot further forward and hoped that would solve it. It may have been optimistic having the tank as far back as I did without using a pump or header tank.
On the field yesterday I had exactly the same problems. I switched from an O.S 8 plug to an OS F, and that did nothing. I tried a smaller prop, an 11×9, and that helped a bit. I then tuned it some more and eventually it ran strong. I had one flight where I landed early because I could hear it leaning out a bit in loops, tuned more, and then suddenly it ran like nothing else mattered, not missing a beat going up, down, sideways or anything. Success! The third flight was suddenly bad again, leaning out. Landed in a hurry, tuned, and suddenly it ran great again.
I have a successful track record of making stubborn engines run good, and I don’t intend to let this one beat me. I suspect the pipe is slightly too long, and I think shortening it might do the trick. I will also try an 11×10 to load it up just a bit more.
The plane flew just like you’d expect. I had some wild deja vu’s while flying. I have lots of flights on the old version of it, so it behaved as I remembered, which is a strange sensation when I was mentally prepared for a maiden flight! I was also surprised at how well behaved it was on takeoff and landing, and how well it tracked straight and level. It has no vices whatsoever.
Here’s a before/after photo, with at least 13 years between the two:
All the pictures from the project can be found here:
The Killer Kaos is covered and painted. I used Tamiya Lexan spray cans to paint over the white Oracover. Before painting, I gently scruffed the Oracover with 1000-grit sandpaper, which makes it less glossy without scratching it.
Tamiya lexan spray paint covers well and is easy to work with.
To avoid paint seeping under the masking tape like shown above, here’s a trick I use:
Spray a coat of clear, flat paint first. If any clear paint bleeds under the tape, it won’t show, and it fills the edge so that the color coat will not bleed under.
A perfect result
The undercarriage looked completely hopeless.
I cut the legs and added a pair of Great Planes axels. It now sits lower and has a perfect stance with clearance for up to 12 inch props.
Tettra 55 mm wheels look great
I repainted an old field box to match
Next up is hooking up the control surfaces in the tail, mounting engine and pipe, and the tank plumbing.
The finished radio bay in the fuselage
My favourite part of any build is the pushrod mechanicals, the electronics and engine installation and so I take my time getting it as perfect as I can. I ground out a huge cutout for the Tettra 400cc tank in the fuselage former. The tank would fit in front in the tank bay, but I wanted it further back in order to not have the CG shift in flight due to the tank being emptied.
The Tettra 400 cc Crank Tank fitted.
The servos were moved forward from their original position and the battery sits behind them, in order to fix a CG issue that the plane had back in the day. Because of that, the pushrods had to be lengthened. I wanted to stick with the original Carbon Dubro pushrods that were already in there, so I simply added a longer threaded rod that extends a bit into the pushrod inner and outer tubes. It adds a little bit of weight, but it adds it behind the CG where I need that weight, and as a bonus it stiffens everything up a little more. BLS451 servos were bought very cheap from a chopper guy switching to HV gear. They are great servos, so I get them whenever I see them up for sale. The throttleservo is a Dymond metal gear digital midi.
To top everything off, I fuel proofed everything using flat black enamel paint, which also looks cool. I’m very happy with how the interior bits and pieces turned out.
The radio bay. Note Tettra switch mount bracket
The aileron linkages. I used a pair of trusty old 9154s that have over 400 flights but are still pretty solid. I added plywood inserts to the ailerons so that the screws have something to bite in. I shortened some Futaba servo screws to fit, as I didn’t want anything visible on the upper side of the ailerons.
This is part two of the Restomod-project. Check out the new tail (above). I made a new fin and rudder, new elevators and modified the stab tips to make everything nice and uniform. I wanted to get rid of the pointy, tall fin and elevators. It’s not radically different, but a lot cooler. The fin and rudder are almost 2 cm lower, something that will tie in nicely with the overall stance of the plane when it’s done. I have more changes in mind!
This has been a tough decision, but I’ve decided to go with a standard Kaos 40 canopy (The plain Tower Hobbies $3 canopy) instead of the long Killer Kaos canopy. It’ll be a whole new look. I wanted to loose the 1990’s styling, and this just looks a whole lot cooler!
You can see comparisons of the old and new tail, plus how it looks with the old canopy compared to the new one in the builds photo album.