|Jul 13, 2012, 04:55 AM|
Traceur - Ultrabatics EPP kit from germany
I just maidened my traceur and I'm having big fun with it. As far as I know it's the only kit available in Europe so I gave it a try. I hadn't found any documentation, there is no manual in the kit nor detailed kit pictures availble so I'm writing my impressions. I have a lot of doubts, because nobody is flying thoose things here, the products have different names (think about glues or laminating films...). I will add more pictures in the next days and more details. I hope we can figure out together if there is room for improvement in the various building - setup - flying aspects.
First of all, some entertainment! I'll go to the boring part later...
All the EPP parts, hot wire cut and delivered into the blocks from where they came from. This leaves a lot of spare EPP for general use and helps protecting the parts during storage and delivery.
A big roll of laminating film. I'm not sure if it is 'new stuff', and I have no clue of the actual thickness because I never saw that thing. I covered all the model with a single layer and I have a lot of spare film.
Two 5mm carbon tubes that fits the slots in the wings. They are a little longer, so one small piece is used for the stabilator system.
Two 3mm carbon spars that fit the stabilator parts and the fixed part of the rudder.
Two 3x1mm carbon strips, almost two meters long.
There is nothing to be used a wing joiner. I found one 7mm hollow spar in my junk box that fits perfectly, by luck. I'm not sure if a portion of the 3mm spar is intended for that, it looked too weak to me so I went my own way.
Fuselage and wing assembly system:
The fuselage is made of three layers: the center one has a small hole for the wing joiner, the sides have a slot the same size as the wing profile. The sizes also have slots to accomodate the 3mm carbon strips provided in the kit: from the wing area to the tail and two small pieces in the nose, around the battery compartment. After glueing the sections, there is a rounded strip of EPP that goes all around the fuselage giving a rounded shape. It's necessary little sandpaper work to make the fuselage looking nice. Once assembled it's very easy to mount the wings in the correct position by just pushing them into the fuselage slots. They seem to be pretty in place during flight but are allowed to offset when crashing. Sounds good to me.
One possible drawback of this solution is that requires some glue to fit all together, increasing the weight. I've used poliurethane glue (Saratoga WD4, looks just like honey, it increases in size forming a sort of foam and it's very tough when it's fully cured) and I tried to make the thinnest possible film over the complete surfaces.
I didn't spent so much effort shaping the fuse and all the model in general. The forecast for the weekend was crazy good and I couldn't wait. Sure it's possible to do better, in all the aspects.
The spar slots in the EPP are bigger than the spar. Again, I used the WD4 glue that filled the gap. Since the wing joiner is bigger than the spar and goes outside, I left the last 15 cm unglued to allow the joiner to slide in.
I've used some of the 3mm strips for reinforcing the ailerons. I cut a slot in the EPP and inserted the strips. I'm not sure if it's the best choice: the EPP is so thin and soft here that the thickness of the strip deformed the ailerons a bit. This can be seen on the other side. Probably the best option is to glue the strips flat over the ailerons.
I've used hitec HS-65HB servos they are my preferred options for foamies because they are tiny, precise and durable, and have enough torque to pull big and rough EPP hinges. They are flush with the wing profile, the linkages I used (nothing comes in the kit) are pretty standard.
Stabilator assembly and tail controls:
Since I'm new to this flying style I decided to skip the mad pulleys and go for a less extreme tail setup. This also allowed to move the servo in front of the wing; that helps finding the correct CG with less ballast. During the first flights I had some flutter problems. This was my fault, due to weak linkage planning and installation. I had some hardware at the slope and I managed to fix that. Since it was my first build in this genre, I made all the electronics installation after covering the model: this lookg ugly but leaves room for tweaking and improvements. Both elevator and rudder controls are made with 0,6mm piano wire and plastic tubes.
Again, the spar slots on both the stabilator and the rudder were loose so the self inflating WD4 glue helped.
It's the first time I used covering materials at all... my previous experience was colored tape on Weasel and windrider Fox. I took some of the spare EPP and made some trials using a modeling iron from hobbyking. It turned out that maximum temperature worked the best so I proceeded. The film appears to be 'new stuff' as far I can understand: it's way thicker than oracover, it's opaque, becomes clear when heated and it doesn't shrink. I found that the film seems to work better on the sanded parts of the fuselage: I left the wings as they came out from the cut and the result it's not very good. I didn't cover the aileron hinges, the film was lifting in flight and making noise. I managed to fix that with some blenderm tape (the one that comes with dreamflight kits).
Later on I read somewhere that 'in order to make the new stuff work, the iron should be able to boil water'. I'm not sure if mine can do so, I'll give it a try by means of pouring some water on it right after disconnecting the power. I'll make some more tests and see if I can do better, maybe with a real flatiron?
Maiden flight and setup:
After fixing the elevator flutter problem, I started making some trials for finding the correct CG. My goal was to make the bird as simmetric as possible: I mean, require the less possible input when flying inverted. The best compromise I found is with the CG way back than I was expecting. Now the bird resembles the Weasel somehow; probably I was just setting up throws and expos to achieve that.
|Jul 14, 2012, 01:55 PM|
Nice flying by you. Nice flying by the plane. Shame about all those nasty little gnats buzzing around.
Looks like a pretty well done clone of the Le Fish as far as the planform and you seem to have done a good job working out build details. Your review was excellent. Thanks for all the effort.
|Jul 14, 2012, 02:21 PM|
Here are some pictures of the fuselage
ImagesView all Images in thread
|Jul 14, 2012, 04:16 PM|
|Jul 14, 2012, 05:22 PM|
I agree with you about the good job engineering the kit as well as that Steve Lange gave the flying world the fish concept for all to use and modify. She looks like a lot of fun and a fast, easy build. It's great to see more people getting into 4 axis close-in light air flying.
|Jul 16, 2012, 03:32 PM|
Here are some more pictures. I've made some trials and discovered that removing the sock from the iron makes a huge difference! I've reheated the wings and tail and now looks good, I'm finally happy with the result.
I've skipped the fuselage because I have some spare film and I'm planning to strip it naked again and rebuild the control systems. The elevator has some hysteresis, seems to keep a bit of memory of the last input; this isn't noticeable when 'dancing' but I tried to fly her like a normal glider and I've noticed that. It's not so much, like a couple of trim clicks. The rudder has more throw when pulling, when pushing the piano wire bends. I have to rethink everithing, including the servo fixing, but she flyes well enough and I'm just enjoying as it is.
|Jul 16, 2012, 03:50 PM|
For information, here is the setup that is working for me:
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