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Specifications
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Specifications
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Introduction
Ever since losing my last sailplane due to structural failure, I have been on the lookout for a lightweight ARF that would permit me to practice LMR Sailplane flying. I wanted a model I could take to the field every time out, but didn't want to spend much time building. Although there are many beautiful sailplane models out there, I was surprised at how heavy most were in comparison to the one I had lost. I came across the Filip ARF on the Hobby Lobby web site that had the features that I was looking for in a sailplane. It had a polyhedral wing, V-tail, no separate spoilers (I like spoilerons), and one that I didn't expect, access to battery without removing the wing. Not only that, but it is incredibly light for a 2M glider. Hobby Lobby was kind enough to provide this model for review.
The model arrived well packaged, with no damage to any of the components. The Hobby Lobby site shows the components as they come out of the box. The wing was labeled as the Filip Millennium, and differed in only a few minor areas, all cosmetic, such as all red wings and tail (which were pre-joined), different decals, and a gray canopy.
The fuselage is manufactured from molded glass fiber, with a perfectly smooth white gel-coat finish. It weighs only 5.5oz, including the sturdy canopy. The wings are built-up balsa, with a ply and spruce I-beam spar. They are covered with red, transparent Oracover, with white leading edges, and only weigh 11.5 ounces. The tail is also balsa, although constructed of solid 1/8" sheet with large lightening holes, weighing only 1.6oz. The kit provides a bag of hardware that includes control horns, pushrods, motor mount, and a sturdy aluminum wing-joiner.
The comprehensive assembly instruction manual shows eight different Filip models are available, with both glider and electric fuselages, either T or V tail, and wings with or without ailerons. Hobby Lobby carries the V-tail A/R/E electric version, which is exactly what I would have chosen if I could have had any plane from the list!
Hobby Lobby's web site says that it will fly on a simple Speed 600 motor, but also states, "more power is more fun and we recommend the geared Speed 500." As we all know, there's no substitute for power. I was certainly pleased to find that the "more fun" option, the recommended Speed Gear 500, was provided for this review! Hobby Lobby was also kind enough to supply a Jeti 350 ESC, the appropriate 12x10 Aeronaut folding prop, and those long aileron extensions that are always hard to find locally!
Assembly
The assembly is simple, and rapid. The manual is well written, leaving nothing to chance. I must say that this is the best ARF assembly manual I have ever seen; most come with simple one page instructions, yet this is a comprehensive assembly and setup manual. For a brief overview of the required steps, consult Hobby Lobby's web pages for this model. They highlight the main areas of assembly, such as servo installation, attaching the tail and elevator linkages, and motor installation. I completed assembly for the first test flights in less than eight hours, including time spent in a few problem areas. I started late one Saturday evening, finished up Sunday morning, and then flew that same afternoon!
The only areas of concern were the V-tail control horns and pushrods, servo mount plates, and the aileron servo installation. The nose was also significantly out of round, which required modification of the motor mount to get a good fit. I also sanded the outside of the nose once a spinner was installed in order to get a better fit, but this was purely for cosmetic reasons. The V-tail control setup was fiddly, to say the least. There is a good explanation in the manual, and Hobby Lobby has good supplemental information on their web site, but it still caused me grief. The provided wire for the control horns was too small, I didn't like the copper wire that I had (too soft), so I ended up fiddling with some stiffer music wire I had laying around. The provided pushrods are popular with many sailplane and smaller model kits. I've seen them in many models, but I just don't like them. Unless secured every few inches, there is a lot of slop in the control linkage. Granted, I could have epoxied the outer tube to the fuselage, but then I would never be able to remove the pushrod for maintenance (I plan to keep this model for a while!). Anyway, I was able to get them installed per the instructions for the test flights, but as you'll see later, I changed this arrangement after just a few flights.
The tail servo mount plate required modification in order to get the servos to fit. This was not a big deal, just time spent. Minor work was needed on the wing hold-down bolt mount plate. It required a little sanding to get it to fit correctly. The final area of concern was the cramped aileron servo installation. Using the suggested HS-81 servos required modification of the servo mount location. It took a while, and some minor modifications to the mount location to get it all figured out. I wrapped the servos with heat shrink, and then use PFM adhesive to attach them directly to the mount plate. I realized that the lead string for the aileron wire was missing! It was not hard to attach a string to a piece of music wire and pull it thru the ribs, but it took a few attempts! Finally, the provided covers were too small. I just applied pieces of transparent red covering I had leftover from another project.
At 42.7 ounces, she came in well under the suggested weight of 44 to 46 ounces. This included the supplied Speed 500 Race geared motor, but with eight CP1300SCR cells. Wing loading comes in at a very competitive 10.4 oz/sq ft. At that time, I had no 7-cell, but many 8-cell packs, and the CP1300's are extremely light for their capacity. Test runs with the provided 12x10 prop pushed the current up a little high for the Speed 500 motor, so I switched to an 11x8 Graupner CAM folder for the test flights. This setup only draws 25A static, for as much thrust (33oz), and pitch speed (~ 50 mph) as the suggested setup. Peak power was measured at 200W, static, which works out to 75W/lb, which is not bad for a can motor! I'd say my setup is better as the current is lower and the motor turns faster, but I suspect seven cells would be a more popular choice.
I installed the suggested Hitec HS-81 servos in the wing, and a couple of HS-55 servos for the tail. Another trusty Hitec 555 receiver was installed for radio control. I set up rudder as well as elevator controls on the V tail, and then programmed my standard spoileron setup for landings.
Flying
Performance was exceptional with the provided power system with the 11x8 CAM and 8-cell pack. She climbed to altitude suitable for 5 to 7 minutes dead air decent in 30 to 45 seconds. At the time I thought "With a small brushless, it will be competitive!" We cover this a little later. Of course, with only a 2m span, you'd better have sharp eyes when you get up to 8+ minute altitudes, but it's easy to see in most conditions given the standard color scheme. I thought about painting the fuselage, or at least the bottom and nose of it, but after many weeks, I decided against that for now.
As I said, I had set up rudder and elevator, and I am so glad I did (I only have elevator on my other V-tails). The rudder is very responsive, and the model can be steered around by rudder alone. The ailerons are used mostly for severe turns, controlling climb out, and keeping the wings level as you find thermals, or on landing. If you wanted a simple R/E ship, you could get the non-aileron version and be very happy. However, I like ailerons, especially when maneuvering at low speed. I also use the ailerons as spoilers to control sink on final.
I had calculated that at 25A peak current, it would have enough power for six or more 30 second climbs. On the first flight, it pulled 45 seconds a couple of times, then another 20 seconds or so, and then landed after more than 15 minutes to check the battery on my charger. I had over 500mAh left in my CP1300SCR pack. In dead air, that's about 30 minutes of fun. In moderate lift, you could probably stay up all day, as I discovered later!
I had forgotten how much I enjoyed flying my last glider (the one with my F7/L160C, now probably several feet deep into a swamp!). I told Ernie, our club president and competitive LMR pilot, I don't remember the last time I flew with a huge grin on my face! Flying gliders in general is such a wonderful aspect of this hobby, but this model is an absolute dream! At that moment, I promised myself I would never be without at least one glider in my fleet again!
Modifications
After a couple of trips to the field, I was still a little unhappy with the elevator linkage. The supplied pushrod setup is not my favorite, and in my opinion, it introduces slop into the control surfaces. Although this is no F5B model, I was also in need of a little more weight in the tail, as the pack could not be moved any further back in the fuselage. These two factors prompted me to install the tail servos on the tail itself. The pictures below pretty much detail how I accomplished this. Each servo was attached with PFM to a section of 1/32 ply, with filler pieces of pink foam sanded to an approximate airfoil shape. The whole unit was covered in light shrink, and then glued to the tail next to the fuselage. The original linkages were removed and the control horns came out much easier than I would have expected! I then installed traditional horns on the surfaces. Now the linkages were short and solid, and it had additional weight in the tail. I also removed the servo mount plate from the nose, freeing up much space for battery installation.
While I was working on the tail, I decided to install a Maxton 4.4:1 gearbox onto a spare Aveox 1010/2Y (old model) motor I had laying around on the bench. With a 14x9.5 CAM, on eight cells, it had power to spare. After a few minutes fiddling with a new motor mount (see picture, below), I had the motor installed. A Jeti 70A sensorless brushless controller came in handy. It was a little overkill for a motor drawing less than 30A, but it was the only spare brushless ESC I had at the time! The geared Aveox is smaller, but of similar weight to the supplied Speed 500 geared motor, as can be seen below.
Performance on this combination was better than the supplied setup. I deliberately kept the power levels down, however, as the model was already reaching 'unsafe' altitudes within 45 seconds. I lost it once in clouds, and that was a scary moment! Perhaps my eyes will adjust in time. However, if I look away for a moment, I have difficulty locating the model again, and I consider that an 'unsafe' altitude. One other time, the conditions were such that the model simply stayed up no matter where I flew. Again, it flew into a patch of light cloud, and I ended up putting it into a shallow dive to recover as quickly as possible. The resulting flutter scared the living daylights out of me!
After a few more trips to the field, the tail was starting to show signs of failure. The individual panels that make up the tail were separated at the root. Although still securely attached to the fuselage, I was not about to leave this unattended. Failure of the tail at altitude is what cost me the last glider I owned. I addressed this by carefully removing about 1/2" of covering at the root, laying down a strip of medium glass, followed by a piece of balsa shaped to fit. The tail felt much stiffer, and I now feel much more confident when I launch! I'll be keeping a close eye on this area.
Conclusion
Hobby Lobby states on their web site that the model comes in at around 45oz, is a slow-flying floater that works well in poor lift, and is capable of climbs of 1100fpm on the suggested Speed 500 geared setup. I can say that their claims for this model are accurate, and that the model performs extremely well for a 2M glider. It fulfilled my requirements by accompanying me to the field on every trip, sometimes being the only model I take. I thoroughly recommend this model to both beginners and advanced modelers alike.