I went to my local slope a while ago (Nov 4th 2005). Usually this area is full of paragliders, so there's no way I can
fly there. But with 41-45KmH winds (measured at the "lip" of the slope) conditions were not too good for them.
Good for sloping though!
Good for sloping if you now your limits...
I should've taken my que from this guy. He decided not to fly...
While standing on the slope's edge, I could not hold my Filip600Sport stable enough to launch. So, thinking
I could punch through (or over) the slope-lip-turbulence, I went about 30 meters back, and launched at
full throttle. Big mistake. My Filip was slammed into the ground, wingtip first. A sickening cartwheel
(twice) and she stopped 3 meters from the cliff's edge.
Wing damage: both wingdowels broke (as designed), wingroots slightly cracked. Fairly easy to repair.
Fuse damage: motormount (ply disc) broken and loose (motor seems ok). Nose gellcoat chipped.
Around the cockpit the gellcoat has chipped of.
The v-tail root is partly cracked, and the v-tail bed is partly cracked.
And a slight crack on the fuse's underside
All fairly easy to repair.
All in all, I count myself lucky. I shouldn't have tried to take of, at least not by launching myself.
Starting with the wings.
The LE dowels were the easy part. I still had a spare pair in my tool box, so I just made another pair,
as I had done before.
The wing root rib had seperated from the foamcore at about the level of the wing hold down bolt,
and was slightly bend. I dropped some thick CA in the gap and taped the rib tightly to the core.
There is a factory installed hard plastic ring in the top of the wing for the wingbolt. The rest of the hole
where the bolt goes through the wing, is un-supported. Over the past year or so of regular flights,
the balsa around this hole has worn, and the hole is much wider now, giving the wings some "play".
Following the good result I had with the tube-in-the-LE-dowel-method, I decided to make a slight variation on a
theme here. I purchased some aluminium pipe of the right internal diameter, and epoxied a piece of
pipe inside the bolt hole of each wing.
The only downside I can think of now, is that I must check the nylon wingbolts
regularly for wear & tear, and replace regularly.
Not crash related, but when I initially build my Filip I did not install the wing servos entirely to
my satisfaction. When I removed the foam to make room for the servo I did not dig all the way down to
the skin. This meant that the servos were about 2mm too high. They were however well potted, and sat
fine so I never thought seriously of making any changed here ("when it ain't broke, don't fix it"). However, with
so many little bits and pieces to fix, I thought I may as well re-do the wing servos. One of the reasons
that held me back redoing the servos, was the fact that I knew I would have to remove all the epoxy I had
used to pot the servos, and I do not own (yet) a Dremmel tool. So when my friend Oshik
offered
his help (and hobby room) to do some fixing, I gladly grabbed the chance. Oshik has much more
experience with plane repairs (and builds) then I have, so I was expecting to learn something in the process.
With his Dremmel we(=he. I just held the vacuum cleaner's nozzle close by) removed most of the epoxy
in the wing, going down all the way to the skin. When I got home I test fitted the servos to make sure
I had plenty of elbow room, and prepared do some carbon fiber-ing.
This is how Oshik showed me how to work with carbon fibre cloth:
- Take a cleaned empty plastic bottle (with a flat side would be best), cut of the top and bottom,
and cut an opening in the side (opposit the flat side), large enough to fit your two bottles of epoxy.
- Place the bottle on a flat heatproof surface and place the epoxy bottles in the cutout.
- Put the nozzle of a haidryer in on side of your epoxy-heating-stand, making sure the opposite
side does not point at anything that shouldn't/couldn't heat up! Don't use your covering heat gun.
It will melt your plastic bottle-epoxy-heating-stand, and most likely also the epoxy bottles. (If you do try
your heat gun for this, make sure you've got lots of pictures to show on RCGroups'
"Stupidest things ever done" thread!)
The warm epoxy is much more like a liquid, so it penetrates the fibers better. It will also dry somewhat faster,
and once dry it will be rock, rock hard.
- While the hairdyer is humming away, cut your piece carbon fiber cloth to size, and place it on top of a plastic (sandwich) bag.
- By now your epoxy should be nice and warm. Mix the two components as per instructions, and poor a
generous amount of the mixture onto the piece of cf cloth.
- Cover this with another plastic (sandwich) bag, and work the epoxy into the cloth with a ruler,
creditcard, or any other piece of straight edged (s)crap you've got lying around.
- Once the epoxy is absorbed into the carbon fibres, lift the top piece of plastic, take out the
cf and place it on the part that needed fixing. Either wear a rubber glove for this, or put your hand inside
a clean plastic bag. It goes without saying ofcourse, that the surface must be lightly sanded, and clean...
Repeat with the other wing. Let cure overnight. Serves two...
For the next step I first thoroughly cleaned the servos and cut of the hold-down lugs.
Then I wrapped the servos in masking tape
and then shrink wrapped them.
This way, if I want to remove a servo for any reason, I can just cut the shrinkwrap and pull the servo out.
I trial fitted the servos a few times, and CA'd two pieces of balsa in place, to make
sure the servos where correctly in place in relation to the aileron control horn. Obviously, when you
pot servos in a new wing, the control horns are attached after potting the servos, so you wouldn't have to do this...
Satisfied that all's in place, I mixed some 5 minute epoxy with 50/50 Bicarbonate of Soda (a heck of
a lot cheaper then micro balloons, available at every corner grocery store, and does the same thing)
poored a healthy blob of the mixture inside the servo cavity, put the servo inside a plastic bag,
and pushed the servo in place. Once the epoxy has set, it is simple to pop out the servo.
Now I centered the servo arm. Or, in this case de-centered the servo arm since I want the servo to have more
"up" travel than "down" to maximize differential.
So the servos were centered, and then the servo arms where attached about 15* forward.
Now, how flush is this?
Now with a small, small dab of Goop/thick CA/hot glue/epoxy, in the servo cavity, push the servo in place again.
Et voila, as the French say. Ze wings are done.
Now the fuselage...
The v-tail repair was done at Oshik's Hobbyroom. We first soaked thin CA into all cracks, and then
sprayed some kicker. That should be enough to hold the surface in place while flying. For some extra
insurance Oshik first cleared out the various types of glue debris that I deposited inside the
tail from my various attempts at fixing the v-tail pushrod sleaves in place. I love that Dremmel tool...
We then cut a piece of cf cloth to size, and proceeded to prepare it as mentioned above.
Only, here we used 30 minutes epoxy. For the servos I used 5 minutes epoxy. It seems the 30 minute
epoxy is much harder when cured then the 5 minute epoxy. Could be an optical illusion, but it certain feels that way.
The crack in the fuse was first cleaned both outside and inside. On the outside we then used maskingtape
to cover the area around the crack, and put a few drops of thin CA on the crack, followed by a shpritz of kicker.
On the inside we placed a small piece of cf cloth for added insurance.
All the other damage was mostly cosmetic. Pieces of gellcoat that had broken off. These were replaced
with some polyester filler; the kind also used in carbody repairshops.
Since the motormount broke on impact, I purchased a new fiberglass one. Previously, the motor
did not have enough down thrust, so this time I planned on doing it right, instead of having to
fiddle around with rings between the motor and the motormount. My only concern was, how to do this.
I remembered seeing pictures somewhere of a dowel sticking out of the nose to see the actual angle the
mount fits in the fuse, so I fashioned my own "thrust-line-indicator" from a 5mm dowel, a disc of 4mm balsa, and a toothpick.
The balsa disc is about 2mm smaller then the mount. Now all I need to do is tape some maskingtape
on the nose and draw a line on top along the centerline, and a line on the side also along the centerline.
I previously had no right thrust (and no need for any), so the dowel should align with the centerline
on top. I will need at least 6* down thrust, since previously I had only 2-3* and a terrible ballooning
problem every time I applied throttle. A corresponding line on the fuse's side was drawn. Now it was a simple
matter of putting the motor on the balsa disc, and insert the whole shebang through the cockpit into the nose.
During the exitement of this procedure I totally forgot to take any pictures, apart from this one while trial fitting...
Once the angles were to my liking I applied a couple of drops of thick CA and a shpritz of kicker.
I will not apply any epoxy at this time. I'm sure the mount is secure enough for flight and I first
want to do a test flight. If the thrust line is not to my liking it will be easy enough to remove the
mount, and align again. With epoxy that would be a major operation.
Although I have allways loved flying my Filip, I became more and more aware that my CG was not where
I would like it to be. Dive tests and inverted flight showed I was nose heavy. "Simple", I hear
you say, "just move that lump of Lipolys back". I would, if I could... When I initially build my Filip
I followed my LHS recommendations (ie. slightly nose heavy). And they were sound. For someone with my
flying abilities, at the time of purchase. The v-tail servos were installed behind the battery,
so a hard landing wouldn't have the pack smash into the servos. Here's a picture how it was (although
I've replaced the PQ26003S with a 40003S2P).
Easy access to all components. That's what you want when you start out. Having had many pleasurable
hours with my Filip (that sounds dirty, but it isn't) I needed some interior re-decorating. To start of,
I wanted to move the v-tail servos to the rear. Less slop, and some weight in the tail. For this I shamelessly
copied Andrew Willets' method, as he showed in his E-Zone Review. I could have attached the servos inside
the tail, but that would mean making big holes in the fuse, thereby weakening the structure. And we don't want that!
So, a couple of Waypoint mini servos (equivalent of the HS55's) were obtained and fixed on two pieces
of balsa. I then added some aerodynamically shaped foam, and covered it with yellow oracover.
These will be attached on the bottom of the v-tail surfaces themselves.
Obviously, I will need to make some servo extension wires. Now, for you purists out there,
I know there are better and more esthetically pleasing methods to do this. But this works for me...
Cut the servo cable in the middle, and strip about 10mm of the plastic. Then twist the exposed wire tightly.
Do the same with the end of the extra servo wire. It pays to get yourself a decent wire stripper.
You'll use it often enough! Cut three pieces of heat shrink tubing for the wires, and I usually add
another larger/wider piece to later cover all three wires. Slide the tubing over the wires before continuing to the next step
Since I only have two hands, I use this contraption to keep the wires still long enough for me to
attack them. Note that for thin wire (like servo wiring) I clip a wooden clothpeg in the crocodileclip.
Now make sure you got the correct color wires (highly recommended)and twist the strands of one set of corresponding colors together.
Clip them onto the "third hand" and solder the wires.
Repeat for all wires.
Now cut of the soldered bits so you have about 3mm of soldered wires left.
Gently fold the soldered parts so they are paralel to the wire.
Slide the shrink tubing over the soldered parts.
And apply heat.
For extra security, I like to add another, larger/wider piece of heat shrink tubing to cover all wires.
Now that the v-tail servos have their wires extended I can put them in their new place. First I
had to draw a line in parralel to the fuses centerline. The tail surface's TE is at right angles with
the centerline, so that was an easy thing to do with my triangle.
With a pencil I drew the outline of the servo ensamble along the line, and with a new X-acto blade
scored the covering a few millimeters inside that line. I then removed the covering. Now I have
a nice wood on wood area to glue the servos in place.
Some 5 minute epoxy, and we're done.
I re-hinged the ruddervators with new hinge tape, and attached the ultra short pushrods. No possible slop here!
At this point I wanted to touch up the various "grey"spots from the repairs. I found a can of
yellow spraypaint that came very close to the oracover yellow. Unfortunately the fuse is slightly paler.
But it will definitely pass the 6 foot test; from 6 feet away you won't notice the difference...
I didn't want to stick the rest of the electrical components straight onto the skin, so I made a
balsa tray. I reinforced the tray by epoxying a narrow piece of balsa on the underside, and epoxied velcro to the top.
I CA'd the tray in place, and put in a dab of epoxy on the two front corners of the tray. Here you can
also see part of the other reinforcements I made. A CF strip from side to side, along the fuse's inside,
and some epoxy fillets on the inside of the cocpit's edge.
A view from the top, empty.
With the motor's battery pack.
And the Rx pack on top of that.
Oh yes, and I also made a nice tray for the Rx's on/off switch. Maybe to be replaced later by a powerplug on the outside.
All that's missing now is a sticker on the inside of the canopy with my name and phone number...
re-maiden 24/03/2006 Well, after following the 10 top reasons to procrastinate on RCGroups far too long, I finally got my Filip ready for flight.
It was a glorious day for the slope, so I headed out there. I didn't get much opportunity to check
out the motor down thrust, but boy did she fly! I did two flights. The first one lasted less the 5
minutes. The CG was right on the wingspar (as the instructions suggested). I had to feed in full "up"
trim, and even then I had to pull all the time. Can you say "nose heavy"?
I landed quickly, and
moved the main batterypack 1cm back.
Launched again. Much better. Only needed about 5 clicks of "up" trim. But by now I was having too
much fun swooping my Filip at eyelevel, and lower, along the cliffs. So further trimming will be done
next time. Starting with the batterypack another centimeter to the rear.
Sorry, no in flight pictures. Hopefully next time.
Final note: with the servos on the tail itself, and the extremely short pushrods, elevator
and rudder are much, much more responsive. Highly recommended.
