Ultra-micro Yak-55 by Dynamic Foamy Review About myself: This is my first official review. Bert Wilson, from Dynamic Foamy was looking for somebody to review his latest kit offering, the micro Yak-55. I m a lucky Canadian whose name came out of the hat, and was quite happy to be selected to try it. I consider myself a decent pilot (not a beginner, but not a pro either), and have only a bit of experience building kits, or trying to design my own airplanes. Please, remember, the kits I ve received are Beta kits, and as such, are still being revised by Bert. Introduction: Dynamic Foamy is a U.S. company who s specializing in making laser cut ultra-micro airplane kits, some of them being designed specifically for the AR6400 type receivers. Their latest release is the Yak-55, which is a laser cut foam frame covered with a strong plastic film. It s following the steps of the great Dynex and Warlord, but with more wing area even if they share the same weight. So, you ve damaged one of your ultra-micro airplanes beyond repair, the electronic is still fine (Receiver, two servos and the gearbox/motor) and you re looking for a new airframe, then, keep reading Kit available here: http://www.dynamicfoamy.com/yak55 micro.html Price: $34.99 covered or $19.99 ready to cover Airplane specifications: Length: 21 (57cm.) Wingspan: 20 (54cm.) Flying weight: 1.2oz (34gr.) Skill: Experienced+ The kits: My kits arrived in excellent condition, absolutely perfectly flat, as they were very well packaged. Since the package had to cross the border to come to Canada, likely visiting the custom warehouse, the box has been to hell. There was just a little bend in one of my kit, but not in any part of the airplane itself, just the unused foam around it. There s an extra piece of carboard, inside the bag, to protect the sheet.
Kit includes: Laser cut Depron foam parts (one large sheet, precut) Carbon fiber wing struts and push rods (two different size) Laser cut micro plywood control horns and push rods guides Z-Bend wire Instruction CD for use in PC Neat little display stand You have to provide: Receiver (suggested SPMAR6400) Two servos (suggested: SPMA2000) Motor and gear box. (suggested: PKZ3624) Propeller (suggested: PKZ3601) Battery (suggested: 150mah to 240mah) In my case, for my first kit, I used all the hardware from a E-Flite 4-Site which had seen better days. So, all long throw servos, which seem to be overkill, thanks to the very short horns. Will most likely try the normal servos as suggested by Bert for my second kit. Assembly: Instructions come on a CD. Currently it s a 4 page PDF (still under revision). This airplane is very easy to put together. You could almost do it just by looking at the included pictures. Suggested glue is CyanoAcrylate. There s a warning about using activator, as it may cause the plastic laminate to come off. With C.A. I think that somebody with a little experience could likely put this kit together in less than one hour. I used my favorite glue instead, UHU POR, because it does stay flexible (after a few weeks, it came loose on the fuselage, where it was stuck between foam and the film so CA may be better there for sure). This may have added a bit of weight, and took more time, but results were perfect. It took me about three hours to complete it, over the course of two evenings. (Mostly waiting for UHU to cure though, but luckily, you can do some stuff in parallel). You may want to mount the stand first, as it can sometime be used during assembly (particularly useful to hold the plane upside down for final tweaks). It s a laser cut kit, so guess what, everything fit absolutely perfectly! No need to force anything in. You need a sharp X-Acto knife to cut the parts out of the sheet. There are only a few minimal cuts to do, to release the parts, which I liked very much. (I ve seen kits where you had to cuts 20 tabs to release even a small part.) The plastic film is pre-cut very accurately, thanks to the laser.
Basically, you glue the tail section to the main wing section. Tape the elevator and ailerons in place and glue the horns. You then install the lower fuse half. While the airplane is still laying down flat, it s time to install all the provided carbon rods. (Push rods, landing gear rods, struts). Everything fall into place very nicely. Last thing is installing the top half of the fuse (glue) and the rudder (tape). Airplane is built and ready to receive all your hardware. There are even some neat little pre-cut C-shape servo spacers, but I didn t use them. I was quite happy about the final result, particularly since my Yak came out to only 1.05oz (29.9gr.) ready to fly but without the battery. Yes, I had a few problems: - Being the lazy guy that I am, I used the 4-Site original push rods to control the ailerons instead of making some from the kit parts. Those are shorter, so I had to glue the ailerons servos a little closer to the ailerons, which shifted the C.G. aft a bit. I can still adjust it perfectly by moving the battery all the way to the front. But it s probably better to build the push rods exactly like in the manual, and glue the servo in the suggested spots as well. This will allow for more C.G. flexibility. (But hey, it s always better to be tail heavy than nose heavy!). I did save a bit of time too! - I stuck a Velcro for the battery without even trying it first. Bert is saying that the slot is just wide enough to stick a battery in it and it will hold in place without Velcro. By adding Velcro, my battery would no longer fit in the slot, so I had to enlarge it a bit. Not a big deal and I like Velcro anyway. Though, now removing and installing the battery is harder. Will definitively try Bert s solution on my second kit. - I didn t line up the little stands properly for the elevator push rods. Told you I m not a pro. They work fine though. Time to fly: Ask me to choose a plane color, and yellow would be pretty far on my list. But wow, do I like it on this airplane. In flight, there s something ethereal about it. I was thinking about adding
a few colors, with Sharpies, for easier orientation, but I totally enjoyed flying it as is, and I m no longer sure I want to change that great look anymore. I had no trouble with the maiden (indoor). In fact, it flew so well that I only realized, on my third flight, that I was flying it tail heavy. (remember those servos I stuck too close to the ailerons?). Yet, I had absolutely no trim! Simply moved the battery forward in my next flights and I could fly inverted with very little elevator input. Next day, I got lucky enough to fly it outside as well. Yes, you need no wind at all, but there s nothing like flying such a nice airplane with no roof or wall around. Overall, the airplane has a good speed range, and no bad tendencies. The ailerons and the elevator are very aggressive. Even if knife-edges are absolutely great, I would have liked a bit more rudder control for KE rolls. Since Bert is always working on improving his design, who knows what the future reserve. I m using long throw servos, so I had to reduce travel. Take off: This kit has no wheels, yet, this is not a problem. On a smooth floor, you only need a few feet and you re airborne. Or you can simply hand launch it, since the airplane easily goes vertical as soon as you release it. I should have used the 4-Site wheels though, even if they add a little bit of weight. Landing: I was sure that the fact that there were no wheels would be a problem, but even if I was landing far from me, I would just throttle it up back to me with ease. As a very light 3D airplane, it s also relatively easy to catch in the air (which I m doing most of the time) Harrier: They are easy to do, and even easier inverted. Just a little bit of wing rocking when you re pushing it too much. Hover: It is very easy to hover at around %70 throttle (and I m using a old 4-Site motor with already 93 flights on it). From hover, you can go vertical but it s not a rocket. (a new motor may have helped) Torque roll: No problem here either. The ailerons are doing a great job. You can get quite a few rolls before you need to work the tail to keep it straight. Knife-Edge: KE are very easy, slow or fast. Not much coupling, no mix needed. Knife-Edge loop: OK, this airplane cannot be perfect. As I said above, rudder is not good enough to do small KE loops, or even larger ones. I think making the rudder slightly bigger would probably help, but I m not an expert Rolling circle: I m still learning those, but it s quite obvious it s not a problem either. Sure enough, this is a 3D airplane, so as such, it s probably too much for a beginner. But technically, unless you re buying brand new electronic, you will be building it from parts from a previous 4 channels airplane you have flown before. If that s the case, you should already have enough experience to fly it. I flew mine with NanoTech 160mah, MiniAviation 190mah and Hyperion 180mah. All those batteries had no problem powering the airplane.
Ready to cover kit: Got one kit ready to cover, and I managed to screw it up! No longer had my usual spray glue, so I borrowed a can of Krylon spray adhesive, quickly tested it (light coat) and it was fine. I then started to stick the film, but most likely sprayed too much adhesive on the ailerons and elevator (thinking it would need more force) and sure enough, it did melt the foam. So now, I cannot use this kit anymore. Should have went and buy my usual 3M spray can! No matter what, I do think that messing with mylar or any type of film for just an extra $15 is not worth it. I strongly suggest you buy the $34.95 kit and let Dynamic Foamy do the work for you (and they do it VERY well). They should come in different colors soon, and you can decorate them easily with Sharpies anyway! Conclusion: Well, it s simple. You have crashed one of your 4-channel ultra-micro too many times, and you re looking for a new airframe, don t look anywhere else. At $34.99, you won t find a better way to build yourself a great 3D airplane. Keep in mind it s a indoor bird first, but yes, it can be flown outdoor when there s no wind. It s even worth buying an extra servo if you re looking for a frame for a previous airplane that only had one servo for the aileron. Sure enough, like any indoor profile, it s fragile and you should avoid crashing it (though, it will take light crash with a smile). Worst case, fixing it is relatively easy. The film doesn t break so you simply glue the broken foam back. I may re-inforce the wing and elevator with a very small carbon fiber rod later on, but for now, no time I have to enjoy this plane as it is, which is literally perfect, particularly for that price. Looking forward for winter season, thanks to Dynamic Foamy and this great indoor airplane!