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Great Planes Yak 55 3D Foamie ARF Review
Jim Walker explores this airfoiled 3D foamie, and finds it to be surprisingly capable on the INCLUDED(!) brushed motor package (even the wobbly prop adapter was included), and also explores a successful Sky & Technologies Brushless ESC upgrade for even more 3D performance.
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| Wingspan: | 33.5" |
| Wing Area: | 297 sq. in. |
| Weight: | 12-14 oz. |
| Length: | 33" |
| Wing Loading (@13 oz.): | 6.3 oz/sq. ft. |
| Servos: | 3 X HS-55's |
| Transmitter: | Hitech Flash 5X |
| Receiver: | GWS RP4 w/base loaded antenna |
| Battery: | Various 3S Lithium Polymer |
| Motor: | Included geared 280BB (also tested with geared brushless) |
| ESC: | Brushed Aveox15 |
| Manufacturer: | Great Planes |
| Available From: | Tower Hobbies |
Introduction
With new inexpensive brushless motors and controllers popping up almost daily and lithium polymers getting more powerful and safer, the 3D Foam is definitely a type of plane that can be cheap AND a load of fun. All of my 3D experience so far had been with flat plate 3D planes made from depron or cut from FFF. When the Great Planes Yak 55 ARF came up for review, it immediately caught my attention because it looked in the pictures as if it actually had an airfoil and the fuselage was thick enough to mount the gear inside. I was curious what kind of construction was used to do this and still keep it light. I was also interested in what kind of performance difference the airfoil would make. Last but not least there was a brushed motor included for the very reasonable asking price and they claimed it would hover with it! This I had to see and was awarded the opportunity to do the review.
Kit Contents
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The Yak55 arrived in a very colorful and appealing box.
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All the parts were carefully wrapped and taped down to prevent damage during shipping.
Once the parts were out of the box I quickly examined them to satisfy my curiousity about the material used to make this more than a flat plate foamy. To my surprise it was made from EPS, the same stuff in styrofoam coffee cups. This would have been very fragile, except that the EPS was covered with some sort of light, translucent plastic covering. The lamination gave the EPS amazing strength while adding hardly any weight. The fuselage also had a carbon rod preinstalled, as well as an integrated plastic battery "case" that strengthened the nose while holding the battery. The wing also had a carbon rod that was installed during assembly and the tail feathers and ailerons were made from a veneered depron type foam. This system of construction was well thought-out and well executed resulting in a light, strong, and inexpensive airframe!
Assembly
The instructions were top notch, as I've come to expect from Great Planes, and there was no need to duplicate the effort here. One thing that was very much left up to the experienced builder was choice of adhesives while assembling the various parts. So presented here is a brief pictorial with notes on my glue preferences.
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The precut wing slot for installing the carbon fiber spar along with filler strips and decals.
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The spar, filler strips, and glue were sealed in the slot with the included decals.
I decided a light coat of 5 minute epoxy would be best for joining the wing halves. When that was dry, just about any type of foam safe glue could have been used in gluing in the CF wing spar. I chose to use polyurethane expanding glue for a couple of reasons. First, I felt it gave the strongest bond possible with the lightest weight in that type of circumstance. Second, the way the kit was designed was perfect for that kind of glue. A big problem with urethane glue was that it could get away from you and foam all over the parts. Since the kit provided depron filler strips and colorful adhesive backed decals, the slot was well sealed, forcing the glue to expand into the foam and not on the surface. This added an evening waiting for the glue to dry, but I thought it was worth it to gain the extra strength and save weight.
The instructions suggested using 5 minute epoxy to assemble the full flying horizontal stabilizer. I did and was satisfied with the results, although CA might also be used. Pinned hinges were supplied in the kit, but I prefer CA hinges. I used CA and the CA hinges to make short work of hinging and installing the rudder and vertical.
I decided to use CA to glue the wing to the fuselage. I felt this adhesive would give me plenty of time to work the glue into the joint and align the wing before it set. The operation went well and I was satisfied with the strength and lightness of the bond. A nice touch was that some excellent hinging tape was included for attaching the ailerons. At this point the airframe was done. I had spent 3 evenings after work to get to this point. The only reason it took that long was due to using the polyurethane glue and taking photos. If I had chosen to use CA for all the assemblies, the airframe could easily have been completed in one relaxed evening.
Radio Installation
Radio installation took one evening and was pretty straight forward. There were pockets for all the components and the servo holes fit my HS-55's with only slight modification. It was definitely a nice change of pace to have all the wires and components tucked away instead of hanging out and taped on the surface. I used a hot glue gun to attach the servos, receiver, and ESC to the airframe. This worked well except for the aileron servo where I was gluing directly to the EPS foam. The heat from the glue kept melting the foam before it cooled and set up. I unplugged the gun and then waited until the glue was cooler but still liquid. I was then able to finish gluing in the aileron servo.
Completion
All the hardware was included and acceptable with one exception. The pushrod for the rudder just wasn't up to the job. All the pushrods, (ailerons/rudder/elevator) were made from fairly thin wire with a "V" bend in the middle. This "V" bend allowed adjustment of the pushrod's length which facilitated mechanically centering the servos and surfaces. The wires for the ailerons were very short and so were OK. The elevator wire was a little longer, but since there was nearly zero resistance because of the full flying stab, it was adequate. The rudder however was a different story. It's wire was quite long and after adjusting the "V" bend it flexed and bent when actuating the rudder. I couldn't get anywhere near the "high rate" throws listed in the instructions. The instructions addressed this problem briefly and suggested attaching a second piece of wire across the "V" by wrapping thread around the two and wicking in thin CA. After some thought, I snipped off the ends of the wire and spliced in some CF rod I had left over from another project. This seemed a better solution to the problem and added no extra weight. Last I installed the included "wobbly" prop adapter and 10-4.7 slow fly prop. These were very nice and added a lot of value to the kit in my opinion.
Preflight Check and Testing
Since I had one of the batteries the instructions recommended, (the Electrifly 1500mah 3S), I chose to try it first. I had done a review of it in an earlier article and knew this battery would give the included ball bearing 280 sized brushed motor all it could handle. I put my whatt meter in line and it reported around 8.8 amps. This was good, but from experience I knew this motor could have done better. I live at 4000' feet ASL and I was sure the 10-4.7 prop was probably included based on sea level testing. I switched to a GWS 11-4.7 and tried again. This time the meter reported 9.6 amps static which I'm sure was closer to sea level performance. At that current draw the plane's power loading was a nice 109 watts per pound, from a brushed system no less!
Surprisingly, with the Electrifly 1500 3S installed, the Yak 55 was seriously nose heavy when I did the final CG check. The instructions called for the plane to balance 3 inches back from the leading edge, but it balanced well forward of that at a little over 2.5 inches. The 1500's fit the battery case almost exactly, so there was no way to adjust the CG other than adding lead somewhere. I really didn't want to add lead at this point because according to my digital scale, the Yak 55 was already at the max weight of 14 oz quoted in the instructions. Since I was going to be either over weight or way off the specified starting point for the CG, I decided the 1500's would not be a good choice for the first flight. Either the Electrifly 3S 1200's called for in the instructions or some other similar second generation LiPoly with high current capability would have been ideal.
The best I had, unfortunately, was a first generation Etec 1200 3S pack. This pack was smaller and I positioned it to the rear of the battery case and then rechecked the CG. The Yak 55 was still 3/16 of an inch forward of the starting CG, but now well within the specified range. I checked the power levels with the Etec pack and the 280BB was getting 7.5 amps and 63 watts. This power loading was a much more sedate 77 watts per pound. I doubted if this was enough to hover, but at least I could safely get in the first flight!
Flying
The first flights went very well and what follows are some mini flight reviews of all the different power setups I used with the Yak 55. I tried different batteries with both the stock motor/gearbox as well as a brushless power system. These results have helped me to choose what setup best suited my desires and means.
Etec 1200 3S with included 280BB brushed motor.
This was the first setup I tried with the Yak weighing in at 13oz even. I knew these components weren't going to give me much 3D performance, but it kept me safe within the specifications set forth in the instructions until I got a feel for how the plane handled. For launching I held the nose high and input close to full throttle. The Yak climbed away smartly and had some, but not unlimited vertical at full throttle. In fact I was a little surprised at how fast the Yak flew in comparison to my other flat plate foamies. The flat foamies almost seemed to defy gravity, just kind of hanging in the air no matter what the throttle setting or wing position. The Yak however showed quite a speed range based on throttle setting and attitude in the air.
A few clicks here and there had the Yak neutralized in upright flight and I began testing out the response with the specified high rate throws. Aileron effectiveness was totally awesome!! The Yak 55's rolls were almost perfectly axial and happened at a blistering pace. Elevator response was also excellent and very true. I tried a couple of waterfalls, but there just wasn't enough power. Next I tested rudder response and unfortunately the Yak seemed to have a lot of roll coupling. Without significant aileron input toward the inside of the turn, the Yak wanted to roll to the outside instead of staying flat and the tail yawing. With the roll coupling and low power loading, knife edges were difficult. Next were snaps and the Yak didn't disappoint here. In fact the Yak did the best snaps of any plane I've owned to date needing hardly any elevator input to do consecutive high speed snap rolls. Inverted flight required significant and constant elevator input, but the Yak tracked nice and true in that attitude. Inside and outside loops could be performed as large or as tight as desired.
Finally it was time to see if the Yak would hover. After a few attempts at hovering I gave up. There was not quite enough power to hover and definitely not enough to punch out of trouble. These attempts gave me an opportunity to check the wobbly prop adapter however. The system worked flawlessly, letting the prop bend out of the way as it contacted the ground. There was no damage to the prop or plane after these unplanned landings attesting also to the Yak's durability as well as the adapter's effectiveness. The low power loading and roll coupling made Harriers just about impossible.
This setup definitely made the Yak 55 live up to Great Planes' claim of "Giant scale performance in a small plane" as far as sport/pattern flying was concerned. However for 3D flight better batteries were definitely going to be needed.
Electrifly 1500 3S with included 280BB brushed motor.
I was still unsure of flying the Yak with this pack because of the nose heavy condition. I decided to contact Great Planes first and ask for their thoughts on the matter. They suggested that I add 1/2 to 3/4 ounces of tail weight to balance the plane with the Electrifly 1500 3S pack. They also assured me that the Yak 55 handled the extra weight over 14 oz. with no problem. Finally, they said that if I did upgrade to brushless, the lighter brushless motor would eliminate the need for the tail weight (not to mention all the extra power!)
Sure enough it took only 5/8 oz. of lead taped to the tail to get the Yak properly balanced. At the new weight of 14 5/8 oz., the power loading was still a respectable 104 watts per pound. I headed to the field feeling much better about this setup. I launched in the same manner as the first setup and once again the Yak climbed nearly straight up with no problem. No trim adjustments were required thanks to the careful rebalancing with the 1500 pack. The speed range didn't seem noticably different, however I now had slow but true unlimited vertical at full throttle. After a few passes to confirm everything was in order, it was time to try some high alpha maneuvers!
Harriers were now possible, although a bit tricky. As long as I kept the Yak moving in a straight line, it would slow down and harrier along nose high. However when I tried to change directions with the rudder, the higher wing loading using the 1500 pack made the Yak snap roll when I would correct for the roll coupling with an aileron input. Hovering and torque rolls were exciting with the Yak requiring numerous and constant corrections while hanging on the prop. With this setup, hovering required close to full throttle, so I didn't try too much prop hanging as there was only a slight bit of stick left to get out of trouble. There was now enough power for high alpha knife edges, though they were still difficult because of the roll coupling. I still couldn't quite complete a waterfall or elevator, but a nice wall was now possible.
This setup definitely was an improvement over the first generation batteries. Some 3D was now possible and the Yak 55 did handle the extra weight reasonably well as I was told. However I still felt that this plane could do a lot better using the included brushed motor. Before I upgraded to brushless I wanted to try a second generation 1200mah 3S battery.
Etec 1250HP 3S with included brushed motor.
I ordered an Etec HP pack from an E-Zone sponsor, Bishop Power Products. After installing it I weighed the Yak 55 and used my wattmeter to measure the new power loading. Weight was back down to 13.5 ounces and the wattmeter reported 9.9 amps and 99 watts. That worked out to 117 watts per pound and over an ounce lighter all up weight! The CG was 1/4 inch forward of the recommended starting CG, but well within the specified 1/2 inch either way range.
Back at the field there was no doubt the Yak 55 was improved. It had more of the "floaty" feel I'm used to with the flat plate foamies I've been flying. Unlimited vertical was possible at 3/4 throttle now which meant that I should have plenty of power to punch out of trouble during a hover. I started with some harriers and noticed that the Yak had lost some of it's tendency to snap out when aileron corrections were necessary. I pulled into a hover and had plenty of power to go straight up if the Yak got away from me. This was definitely the way to go with the included brushed motor! Since I had plenty of zip to get to altitude quickly, I took the Yak 55 up for a blender. It did a perfect rolling downline and then flattened right out into a spin. It was great!
Hovering was easier and SAFER with the extra power and lower wing loading. The Yak still required plenty of corrections though, which made it hard to stay in the groove. Once again I still couldn't quite complete a waterfall or elevator though the Yak seemed to have enough power now to do these maneuvers.
I was satisfied that this was indeed the ideal setup with the included brushed motor. Furthermore I felt that the Yak would do 3D without brushless power, just as Great Planes claimed. A major acheivement in my book!
Upgrading the Yak 55 to Brushless Power / Quark 22 Brushless ESC Mini-Review.
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| Designation: | Quark 22 |
| Weight: | 1 oz. (29g) |
| Dimensions: | 33.5 X 25 X 6mm |
| Current Handling: | 22 amps (35 amps surge) |
| Modes: | 8 programmable for planes, cars, and helicopters |
| Manufacturer: | Sky and Technologies |
| Available From: | Purchase Quark22 |
During flight testing a brushless ESC came up for review. I'd planned on upgrading the Yak to brushless power and the Quark 22 ESC from Sky and Technologies provided the last component I needed to do the upgrade. In fact, I tried several power systems for the Yak and I found the results interesting.
The Quark 22 brushless ESC from Sky and Technologies is truly a feature rich piece of equipment. With 8 different modes to accomodate planes, cars, and helicopters, there wasn't much this ESC couldn't do. Since I wasn't using the Quark 22 in a helicopter and I've never flown a helicopter, it's hard for me to comment on the features and functionality of this product used for that purpose. I can say however that from reading the instructions it seems from my limited knowledge that the Quark 22 should be able to do whatever the helicopter pilot might need. I will definitely not let this product get away from me in case I ever decide to give helicopters a try!
As for planes, the Quark 22 has every programmable option you could want. The main programmable features of note were:
- LVC for all different battery chemistries.
- Reversible direction without switching wires.
- Adjustable timing for outrunners versus standard brushless motors.
- Ability to control throttle stick travel with "turbo" feature.
The only down side to this great product were the instructions. Programming ESC's from your transmitter is inherently going to be a chore. Unfortunately the instructions were hard to understand and many of the functions weren't explained well so it made this task even more troublesome. After several times through the manual and a lot of trial and error I was able to do everything I wanted, though.
I used my MiniAC 12/16 in a GWS gearbox geared 5.33:1 swinging a GWS 12-6 along with the Quark 22. Some surgery was necessary to upgrade to brushless power, but nothing too outrageous. After the transformation was complete the Yak now weighed in at an even 14 ounces. Still within the listed weight range in the instructions. The CG was still approximately 3/16 foward of the 3 inch mark suggested by the instructions, once again well within specifications.
The wattmeter was again hooked in line with the new brushless setup and it reported 12.5 amps and 122 watts. This worked out to a power loading 139 watts per pound! The Yak also now had the benefit of an inch diameter more of prop and 1.3 inches of pitch.
While I had the Yak in for maintenance and upgrades so to speak, I decided to see what I could do about the problems encountered so far. After rechecking all the throws and surfaces I noticed that the full flying stabilizer was tilted slightly. Upon closer inspection it looked as though the factory installed bearing was not parallel with the wing. A little careful heat gun work corrected this. As for the problem of not completing hard pitch change maneuvers, I decided to add more stab throw. I did this because I suspected that under the intense pressure of waterfalls and such, the elevator pushrod wire might be buckling somewhat. Extra throw would overcome some of that if that was the problem.
Flying the Yak 55 ARF with Brushless Muscle.
The numbers didn't lie and this was by far the best setup for 3D! Unlimited vertical was now possible on a little over 1/2 throttle. Full throttle climb outs were insane with the Yak getting hard to see in a hurry. Getting out of trouble was now simply a matter of firewalling the throttle for a couple of seconds and thus quickly getting away from solid ground. Unfortunately the extra weight of going brushless again made the Yak a handfull while doing harriers. Hovering was easier with the new setup, probably for several reasons. More instant power for corrections, getting rid of the stab tilt, and finally a slightly more rearward CG. The Yak still required more corrections than I liked though, and I planned on experimenting with a more rearward CG to see if this helped stabilize the Yak as it had on other planes.
Though the heat gun adjustment on the stab didn't help the roll coupling problem with the harriers, it did seem to help the Yak on knife edges. High alpha knife edges were much easier and the extra brushless power made knife edge loops possible. Next on the list was a waterfall. For a second it seemed I was going to complete the maneuver but then I heard a fluttering sound. Then I saw the prop freefalling to the ground and the Yak was dead stick! The Yak glided in with no problem and after retrieving the prop I saw no damage. It was clear that the rubber bands had simply given way on the wobbly prop adapter. I reattached the prop with the spare bands included in the kit and tried again, but got the same result.
Something better was required for the brushless system, and so I bought some 1/16 X 1/2 i.d. O-rings from the local Lowes. With a couple of those installed there was now much less play, but the prop still had enough flex to give during landing to protect it. Another waterfall was attempted and this time I got one - of sorts - with no fluttering sound. However the more I tried to do a waterfall or elevator, the worse the Yak performed. I finally gave up and dove for a quick landing. To my surprise the Yak looked like a porpoise. On closer inspection it was clear the elevator pushrod had progressively gotten weaker during the test flying and was now constantly flexing. Also I noticed that the foam around the stab bearing had been weakened by all the fluttering.
Back at the workbench I decided to take Great Planes advice from the instructions and put a piece of wire across the "V" bend, wrap it with thread and CA it. I couldn't use CF rod this time because the elevator push rod wire didn't take a straight run to the stab. It had to bend sidewise in the middle to clear the full flying stab. As for the bearing, I used polyurethane foaming glue to strenghten the area. I gave the glue a day to dry thoroughly and then checked everything. The pushrod was much stiffer and the bearing was once again firmly mounted in the tail foam. From all this trouble and extra work it was clear I should have strengthened the elevator pushrod before the first flight after the "V" bend had been correctly adjusted.
Back at the field there was no doubt that the Yak was improved! The porpoising was gone and waterfalls were now possible in either direction. Walls were even better now though I still couldn't get the Yak to complete an elevator. I was concerned that the extra elevator throw past the recommended high rates would be too much now that the pushrod was shored up. This was not the case though and I enjoyed the increased effectiveness of the elevator for extreme 3D maneuvers.
I still wasn't satisfied though because hovering and harriers were difficult. Also, as well as the Yak 55 performed otherwise, I wanted to figure out why it wouldn't do an elevator. There was one thing left that I hadn't tried and that was a rearward CG. All through previous testing the Yak had been balanced somewhere ahead of the specified starting CG. I decided to add the piece of lead I had used earlier with the heavier 1500 3S pack. This time however, taping lead to the tail would take me all the way to the rear of the listed CG range instead of just eliminating a nose heavy condition.
On the next test flight after the CG change I was rewarded with a completely different plane! The elevator response I had been looking for was all there plus some. Elevators were finally possible and had that antigravity look to them. Also with the new CG I had to trim in quite a bit of down elevator. This resulted in the Yak needing hardly any input to maintain inverted flight and made the plane very close to neutral in the pitch axis. The biggest bonus though was hovering. The Yak was now quite easy to hover and torque roll, a real pleasure. High alpha knife edges were also greatly improved. There was one down-side to the rearward CG unfortunately. Having to add the lead to get there pushed the weight back up to 14.75 ounces, 3/4 of an ounce over the upper limit. The Yak 55 again handled the extra weight with no problem except in the harrier department. The higher wing loading coupled with the rearward CG pretty much made harriers impossible. Any aileron input with the wings level and the nose high resulted in severe wing rocking or a violent snap roll.
At this point I felt I had explored every aspect of the Yak 55's envelope and so here is a report card.
| Maneuver | Grade | Comments |
| Loop | A+ | As tight or as large as you want, inside or outside. |
| Snap Rolls | A+ | Best of any plane I've personally owned. |
| Roll | A+ | Almost perfectly axial, extra high rate. |
| Inverted Flight | B+/A | Needs a significant input to maintain with forward CG, excellent with rearward CG |
| Knife Edge | A | Easy with plenty of rudder authority. |
| Inverted Flat Spin | A+ | Best of any plane I've owned. |
| Hovering | B-/A | Will hover with brushed or brushless power-needs a lot of correction with foward CG, excellent with rearward CG. |
| Harriers | C- | Harriers are difficult because of rudder roll coupling and snap rolls occur at higher wing loadings. |
| Blenders | A+ | A joy to watch and perform with this plane. |
| Waterfalls | B/A | Possible with brushless power and the linkages strong and tight, excellent with rearward CG. |
| High Alpha Knife Edge and Knife Loops | A/A+ | Possible with brushless power and excellent with rearward CG. |
Downloads
Conclusion
The Yak 55 was a good value for a 3D dollar, especially considering the high quality brushed motor, prop, and adapter that were included for the price. Another aspect that really increased the value of the Yak was its durability. There were many rough, unplanned landings while testing all the different equipment, setups, weights, and CG's. The Yak 55 took it all in stride with hardly any repairs necessary! With the right lithium polymer battery, the included motor will indeed hover the Yak 55 and do most any 3D maneuver you wish. Sport/pattern flight performance was outstanding. Upgrading to brushless power was simple and readys the Yak for almost any extreme 3D maneuver you can imagine. I definitely recommend this plane to novice through advanced 3D pilots!
The Quark 22 performed flawlessly throughout all flight testing. It's light weight, fairly high current capability, and feature rich firmware will keep it in my fleet for some time to come!
| Great Planes Yak 55 ARF | Quark 22 ESC | |
| Hits: | Great looks Great price with included hardware Quick assembly Much more durable than most 3D foamies Outstanding pattern and good 3D flight with included brushed motor Easy upgrade to brushless power at any time | Light weight Integrated heat sink 8 programming modes for cars/planes/helicopters Plenty of features for airplanes |
| Misses: | tail pushrods are weak & need to be reworked/replaced before 1st flight Battery case leaves doesn't allow for CG adjustment without lead Harriers are difficult | Poor instruction manual |
Discussion
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Mar 11, 2005, 01:24 AM
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Sonoma County
Joined Sep 2004
13,043 Posts
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Just Installed a Himax 2808-0860 Outrunner on mine
My stock motor started out really strong but died a slow death for some reason. No matter, I had already ordered a a outrunner combo to retrofit it to. It is great now!! The little Himax lasted over 20 minutes on a Thunder 1300mah 3 cell! It has strong vertical and I even managed to get some torque rolls going. This is my 3d trainer. I want to try moving cg back a little next. I am spinning a 10x4.7 and pulling about 7.85 amps WOT. Should I go up to a 11x4.7 or 12x6? AUW is 12.9 oz on mine. LOVING IT!
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Mar 13, 2005, 02:42 PM
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Joined Oct 2004
736 Posts
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As I opened this article I was glad to see that the YAK55 was going to be reviewed. After All, I had bought two of them and wanted to see what the consensus on the product was regarding the EPS foam construction. I was happy to see someone had a good experience with this plane.
With my two, and the countless that have been sold at the LHS, performance has left us with many questions. We are not sure whether it was a manufacturer defect, or just a bunch of people who are not experienced in 3D...but everyone here who has flown one (4 whom I talked with) has had the fuse crack after 3-5 landings...from the base to the top; right around where the alieron servo inserts. I had never 3D'd before, so I opted to buy another one after CA-ing mine back together too many times to count. After my second light and easy landing...same thing...cracked fuse. I figured I would wait until an EPP model came out...this plane was apparently not up to the challenge of a new 3d flyer, or some of the exerienced ones, either. Still, for $54.00...one cannot expect the moon. It WAS fun to fly and much better than those paper thin 3D models that come apart if you hold them too firmly. Still love GP and their products...I am just not a 3D guy, I guess. --C |
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Mar 13, 2005, 11:47 PM
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Ashburn, Virginia, United States
Joined Dec 2003
879 Posts
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Hmmm, I used epoxy to join the wing and fuse and have had no issues at all after more than a dozen flights. I dorked it today in a low torque roll and didn't cut the throttle fast enough but it still held together fine. Maybe try epoxy on all wing joints... I found ca good for everything else though.
Also, I found it flew better lighter... it is kinda heavy with recommended gear and the high wing loading makes some things harder so i went to a park 370 brushless in a gws gearbox (only .1 oz lighter) but went from a (~14.2 oz AUW) 1320 3cell tp pack at 3.4 oz to a 900 mah one at 2.2 oz (~12.3 oz). This allowed me to also remove 0.5 oz of weight from the tail. I think it flies better like this. So much so that I might try putting my park 370 5400 and using a 2s 850 pack or so to lighten it a bit more although that may not be enough of a difference to justify the power loss at 2 cells... |
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Mar 30, 2005, 11:19 AM
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Joined Nov 2003
6 Posts
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Picking some nits
I picked one up at my LHS Monday. Here are some thoughts so far.
As usual, GP has some good ideas but executes them poorly. The plastic box is poorly formed and does not fit well. I finally weighted the fuse down on a sheet of glass and glued the box to the plastic sheet on the side opposite the box. A 1550 mAh Tanic pack will not fit in the box, so I will have to go with my 1050 mAh pack. The "door" is a joke. I removed it and cut some slots for velcro straps to hold the pack and motor control. The wings are not the same airfoil at the root and require some guesswork to make sure both the panels are at the same incidence. This is as far as I have gotten at this time. It sounds like I better do some reinforcing of the fuse at the aileron servo cutout. Unless this plane flies a lot better than my flat sheet foamies I would not buy another one. I plan to use a Himax 2025-4200 with 6.6:1 ratio gear box. |
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Apr 15, 2005, 09:27 AM
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USA
Joined Feb 2002
1,160 Posts
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I have been flying a yak 55 for about 2 weeks now. Mine never flew with stock power because my pixie 20 freaked out, and I lost the programming booklet...Now it has a himax 28081160, 3s thunderpower 860, and ph10. The only prop for this set up is a gws 843. Too much pitch speed, and the little yak is already too fast for its size. The full flying stab needs to be connected very securely to its servo or it will flutter. All up weight is 11.3 ounces with cs4.4 servos and gws r6p, dual ail servos, light antenae. Planning to try a 2808 860 or what ever the slowest wind is to prop back up to 1047, and bring pitch speed down. I did fly it briefly on rz300 power geared 6.6 turning a 1047 on either 3s 1320 or 3s 860. Power was way too much, and it was unsafe at full throttle due to stab flutter. This was at 13.5 ounces using hs 55 servos and expert receiver.
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Apr 15, 2005, 01:02 PM
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Ashburn, Virginia, United States
Joined Dec 2003
879 Posts
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Both of your setups sound nice. I might try another one with the intention of making it super light with smaller servos and a little outrunner and even smaller lipo, maybe the TP 730 which I hear so many good things about.
My current YAK55 is still going but I've crashed him a lot. I'm now constantly skimming the grass as my comfort level has gone up a lot since the lightening to 12.5ish ounces and many many flights now. The glue and tape are adding up and its getting a little floppy! One cool thing, I think, is that the plastic battery door came loose in a crash so at certain rpm and attitudes it flaps against the foam and makes an engine noise like a playing card in your spokes! I like it and just left it! |
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Apr 15, 2005, 08:47 PM
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USA
Joined Feb 2002
1,160 Posts
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Yeah, I cracked mine up today, and just keep adding little strips of laminated 1/64 ply to make it stronger. So far its a bit out of tune and is a bit frustrating to fly, especially in this windy weather lately.
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Last edited by topforce; Apr 16, 2005 at 10:28 PM.
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Apr 15, 2005, 10:37 PM
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Ashburn, Virginia, United States
Joined Dec 2003
879 Posts
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I know what you mean but I think you're at the right weight but maybe need that other motor for a bigger prop. Mine really got "floaty" once I dumped the heavy 1320 (and they recommend a 1500 3s!), must all be the 11x4.7 prop I use on the eflite park 370. I can knife edge fast and slow it down while descending until its still knife edge at 80 degrees from vertical at 3 mph and then turn around and go back the other way.... inverted harrier at 3mph easy... I mean its no Tensor but it can do good 3d AND fly and glide in high wind (at least high foamy wind) I have flown it in 15 mph wind as a sport plane and it did great. its very flexible overall. Give it a chance, I'm glad I did!
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Apr 16, 2005, 10:36 AM
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USA
Joined Feb 2002
1,160 Posts
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Yes, I think pitch speed is still too high. Will try to remedy this without buying a third motor for this plane. Oh well, its nice to have so many pretty blue motors lying about, or flying about! currently we have installed a himax 2808 980. LHS didnt have an 860 or thats what would be installed right now. I do like the overall cleanliness of this design. With all the wires running through the center channel, and servos tucked inside the fuse, its very slick and impressive just to look at. Got a chance to fly in still air, ith 1047 prop. Much nicer! The ph 10 needs to have a soft shut down with this set up, but in flight it dosent seem to bother. In static it deffinately over amped in a few seconds. This must be pushing the limits of motor, esc and battery! After a long flight of much careful floating around and a few blasts into low orbit, everything came down cool to the touch. I noticed this one needs to be flown in on power to maintain elevator authority. This is a delicate balance because the more power is used the more compramized is the elevator linkage. Mine is a carbon fiber and steel rod with z bend at the ele and a screw conector at the servo. Its very stiff and positive, but still needs ball links and a real nice servo with a tight centering.
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Last edited by topforce; Apr 16, 2005 at 10:24 PM.
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Jun 22, 2005, 11:01 PM
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vancouve,wa usa
Joined Jun 2004
5 Posts
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outrunner mount
Any suggestions on the best way to mount an outrunner motor? What size?
Thanks |
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Jun 23, 2005, 09:31 AM
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Ashburn, Virginia, United States
Joined Dec 2003
879 Posts
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Try the Cobri rotating case mount at e-flightline.com in the gearbox page. I've tried many home brew mounts in the past that all had weaknesses and were really a pain. This one is aluminum and perfect.
Axi 2208/34 with a light battery should be good for slow 3d and high alpha stuff and a 2212/34 with a larger battery good for sport plane stuff in higher winds... should hover great either way but the larger motors need bigger batteries and the slow stuff then suffers a bit. If you're not past the beginner stage yet I'd say get the bigger one because you can maybe do more in the wind etc although I did fly a yak55 with the smaller axi and it seemed to have a lot of power no problem, it used a small tp730 3s pack I think. |
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Jun 23, 2005, 11:25 AM
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vancouve,wa usa
Joined Jun 2004
5 Posts
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been flying 3d quite awhile. have a axi 2208/34 and an eflight 400. Tunder power 860. Sounds like a good combo for slow 3d stuff. Love the mount...thanks for the infor i will try it.
V |
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Nov 02, 2005, 03:18 PM
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Young Harris, GA
Joined Feb 2004
80 Posts
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Quote:
Rich |
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Nov 03, 2005, 10:12 AM
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vancouve,wa usa
Joined Jun 2004
5 Posts
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change in outputshaft location
yes, you are correct - the output shaft will not be in the same location, however, that did not seem to create any noticable problem for me...I suppose you could expoy another piece of square stock below the origional and attach to that ....that would get you much closer.
Good luck! |
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