Shop our Airplanes Products Drone Products Sales

Carl Goldberg Products Yak 54 EP ARF Review

You're about to be let in on a secret! Ralph Squillace spills the beans with this RCGroups exclusive review!

Splash

Introduction

Carl Goldberg Products Yak 54 EP

Wingspan:40.25 in (1022 mm)
Wing Area:343 in” (22 dm)
Wing Type:Mid-mounted, semi-rectangular with symmetrical airfoil
Weight:27-29 oz (765-822 g)
Length:37.5 in (952.5 mm)
Servos:Futaba S3114 micro (FUTM0414)
Transmitter:Futaba 6EX FASST (FUTK6900, transmitter and receiver only)
Receiver:Futaba R606FS (FUTL7635)
Battery:Electrifly Power Series 1500mAh 3S lithium polymer (GPMP0613)
Motor:Electrifly Rimfire 35-30-950kv brushless outrunner (GPMG4590)
Propeller:APC 11x4.7 slo-flyer (LP 11047)
Spinner:DU-BRO 2" black (273)
ESC:Electrifly Silver Series 25A brushless (GPMM1820)
Manufacturer:Carl Goldberg Products, Ltd.
Available from:Coming soon to a Great Planes distributor near you

Timing, as they say, is everything.

As many of you may already know, Carl Goldberg Products, Ltd. was acquired by Great Planes/Hobbico back in August 2007. This particular plane was in production just prior to the change of ownership and, well, it missed the boat in terms of promotion and advertising.

At this writing, I have what may very well be the only Yak 54 EP in private hands, but I hope to change that soon by convincing you to get one in your hands. Before you continue, please make a note to yourself to in turn convince your local hobby shop to carry this model. If you're half as blown away by this model as I am, the hobby shop itself may be the last thing on your mind!

“Yak” is the name given to the plane by its creator, Russia's Yakovlev Design Bureau. Powered by a 360-horsepower radial, the prototype first took to the air in 1993 and has been thrilling air show audiences all over the world since then.

Making this even more interesting is the fact that the one and only full-scale Yak-54 flying in the US, Russian Thunder, is now owned by Jim Bourke, the man who just so happens to own the very site you're currently viewing!

Let's get started!

Kit Contents

As with all Carl Goldberg ARFs, the individual components come precovered and predecorated with a high quality heat-shrink covering. You also get:

  • Full hardware package
  • Vacuformed Lexan canopy preinstalled on built-up frame
  • Painted and decorated fiberglass cowl
  • Carbon fiber wing reinforcement tube
  • Preassembled and adjustable motor box
  • Decal sheet
  • Comprehensive spiral-bound assembly and setup manual

You will need:

  • APC 11x4.7 slo-flyer propeller
  • 2" spinner
  • 25A or greater brushless speed control
  • 970kv outrunner motor
  • 1500mAh 3S lithium polymer battery
  • Four-channel or greater aircraft radio
  • Basic tools and adhesives

The box art for my particular plane states that the Yak 54 is glow compatible (hardware and instructions for conversion not included). The tail-mounted elevator and rudder servos make for a lot of room in the fuselage for a fuel tank and a .19 two-stroke would probably be right at home up front. But we’re concentrating on this beauty as an electric!

Assembly

Wing

It was apparent that a lot of care went into this model; the ailerons were actually built up as opposed to simply being solid hunks of balsa covered in film. Good thing, too; the ailerons run the width of each wing and make up close to 25% of the total wing area. Thanks to crystal clear text and photos, they went on with no trouble at all with the included CA hinges and with all of the trim lining up with their counterparts on the wing. I'm pleased to say that the result was two of the lightest wing assemblies I've ever seen, on par with many foamies.

The required accessories listed in the manual include four 6" Y-harnesses; what you'll actually need are regular 6" extensions. The manual also says that there are preinstalled strings to aid in threading the lead, but I found none. Even without the string, you'll find threading the leads to be very simple. Hobbico is aware of both of these manual misprints and is correcting them for future runs.

There's also been an update since the manual was published. Suggested servos are Futaba S3110 micro servos, but these have been superseded by the wonderful new S3114. These miniature engineering wonders are designed to be glued in place to save weight.

Be careful when mounting the very small pushrod horns to the ailerons. There isn't a lot of balsa for the things to grab onto because of the built-up construction. I knew that the pins were going to push through the other side, but that meant that much stronger a bond once I glued them in. Once installed, I clipped the ends a bit.

The pushrods themselves are of considerably greater diameter than the holes provided in the horns, but the horns are of far better quality than the ones I had on a previous Goldberg park flyer and were still plenty strong once I opened up the hole to accept the pushrod.

On the other hand, the clamps which attach to the servo arm are the types with the screw-on post instead of the clamp with the nylon retainer shown in the manual's photo (again, Hobbico is aware of the misprint and is working to correct it). Tightening the knurled nuts on the post meant a clamp that wouldn't swivel, and I wasn't about to tighten it part way and depend solely on Loctite. Hobbico to the rescue with the bulk pack of Great Planes Screw-Lock clamps I bought for another recent project. The pushrod openings are a bit larger than the factory offerings which means you'll need 4-40 x 1/4" allen bolts to replace the 1/8" bolts in order to secure the pushrods.

Fuselage

With the wing halves complete, it was on to the fuselage and its straightforward mounting of the aluminum main landing gear and tail skid. There's even a bit of "bling" provided in the form of lightweight metal wheels with foam tires (each with a bit of a wobble) but as you can see in the photo, the factory neglected to cover part of the well in which the gear resides. I later fixed that minor quibble with some black self-adhesive covering I happened to have on hand. The phillips head bolts used to attach the main to the fuselage are far longer than the 3x18 mm described in the manual, but there's no interference inside because of them. However, the 3x18 mm socket head bolts used to hold said wheels are just long enough to accept the attaching nut; lockwashers are provided but not mentioned in the instructions. Unless you go to a longer bolt, forget it. Use Loctite on that nut and hold the jam nut in place with needle nose pliers when you tighten it down.

Attaching the tail skid was as simple as lining it up per the instructions and drilling 1/16" holes for the screws. I went one better and reinforced the holes with a dab of thin CA before screwing everything down. I personally don't care for tail skids or non-steerable tailwheels, but I have to capitulate here and say that a skid is a good idea in keeping with the lightweight nature of the Yak. Besides, the exercise I'll get from retrieving it from the runway will be a plus.

As you can see, Carl Goldberg's designers designed the Yak to be as strong as possible using the least amount of wood, and it appears as if they've succeeded. As viewed from underneath, the sheeted turtle deck is a work of art as are the various components of the airframe. This is the first ARF I've ever seen which is as attractive on the inside as it is on the outside. However, there is a LOT of exposed space along the bottom of the fuselage.

Tail

This too was a straightforward installation with no hassles of which to speak. The lateral measurement of the horizontal stab is 6 1/2 inches to either side. Triangulating the stab with the wing was just as easy with a distance of 20 3/4 inches from the outside corner of the aileron to the rearmost corner of the stab.

Once everything is squared up, make pencil marks on both sides of the stab where it meets the fuselage. Remove the stab and some covering from inside the pencil marks. The red covering is a bit difficult to remove, but nothing a bit of patience and a sharp X-Acto won't overcome. Mix up some five-minute epoxy, apply it to the stab, insert the stab, realign it (easy thanks to the pencil marks), remove the excess epoxy with some alcohol and let it set. I didn't have five-minute epoxy on hand, but my trusty fifteen-minute epoxy worked fine.

No holes are provided for the elevator joiner wire, so you'll have to c-a-r-e-f-u-l-l-y make your own. Once installed, the trim on both the elevator and the stab line up beautifully.

There are three hinge slots cut in the rudder, but only two are needed.

The only caveat I can offer here is to keep the very large hinged surfaces as closed to the fixed surfaces as possible to prevent flutter later on.

Radio Installation

The servos for both the rudder and elevator mount externally in the tail, so begin by removing the covering around the mounting areas. As was necessary for the wing, I needed to get out the Dremel and open up the holes to accept the Futaba S3114 servos. Like the wing, the manual once again called for 6" Y-harnesses when only standard 6" extensions are necessary.

Mounting the servo horns calls for the same procedure as the one for the ailerons. Once again, you'll need to carefully open up one of the holes in the servo horn to accept the pushrod. I'm going to keep a real close eye on all of these horns since there isn't a lot of material left. At the first sign of wear, I plan to drill them out and replace them with horns with some more meat on them.

Speaking of pushrods, there was a slight mistake in my kit. The elevator and rudder pushrods should have been different lengths, but they weren't. The elevator pushrod was way too short. (Hobbico is aware and is working to amend this.) Fortunately, I happened to have a pushrod on hand which I'd salvaged from an old ParkZone J-3 Cub fuselage. It was the same 2 mm diameter as the Goldberg rods and was plenty long enough and then some. Once it was trimmed to a useable length, it was indistinguishable from the factory part. It even had the same finish.

Now is a good time to center up your servos if you haven't yet done so since this is time that you are instructed to install the receiver. In keeping with the first-class, all-Hobbico theme of this build,I got a new six-channel Futaba 6EX FASST spread spectrum transmitter and receiver for use with the Yak 54. To say that I'm impressed with this system is a monumental understatement. It's easy to program and will make fine-tuning the Yak a lot easier than trying to fly with my old four-channel sport radio. If you're flying a four-channel or you wish to use a Y-harness to control both ailerons via a single channel, wrap some Hobbico 1/4" foam around the receiver, secure it with a rubber band and tuck it in. There's oodles of space in the fuselage. I elected not to wrap foam around the receiver as yet since I planned to use the computerized flaperon function on channels one and six once the wings were installed.

Completion

You're now instructed to drill the holes for the pre-painted cowl. Get some low-tack masking tape, put a piece extending rearward about 1 1/2" over each of the three mounting tabs, mark the center of the tab and draw a line rearward exactly one inch from the mark on the tab. Once the cowl is lined up, simply measure forward one inch and drill a 1/16" hole in that spot.

Installing the Rimfire motor came next on its rather ingenious modular motor box with its built-in thrust angle. You're then instructed to mark the front of the box as to which way is up. If you're using the recommended 35-30-950kv motor, you'll have to drill out the hole in the center of the box in order to clear the motor shaft. Once you do, the laser-etched alignment lines make lining up the motor a snap. I used a pin vise to make pilot holes before drilling them out to accept the recommended 6-32 hardware. The hardware wasn't included with the motor, so it was off to the hobby shop for some of those neat, closeable Great Planes hardware packs. You could easily get away with 1/2" long bolts, but I wanted to err on the side of caution and use 3/4" bolts in case I had to shim the motor for any reason (which I didn't). Do use a drop of Loctite on each when attaching the nuts and washers. I used some Loctite on the prop adapter as well.

Slide the box into the front of the fuselage, and then install the cowl with the supplied #2 screws. The idea here is to be able to slide the box forward or aft if necessary to clear your particular motor/prop combo, another ingenious touch. Using the recommended Rimfire meant installing the box as far as it would go and attaching it for good with some thick CA. Attach the prop and spinner, install the wings and carbon fiber reinforcement tube, screw down the wings from inside the fuselage with some #2 screws, hook the aileron servos to the receiver and you're done!

A plane like this wouldn't be totally complete without decals. For this very special coming-out party for the Yak 54 EP, I not only used every decal on the Goldberg sheet, I also added some decals heralding the Electrifly power plant and Futaba FASST radio. Camouflaged it ain't, friends.

An early winter blast through the desert made it impossible to fly immediately after I finished the plane, so I spent the day before I was scheduled to take it up with our club president setting the aileron, elevator and rudder throws (1/2", 3/4" and 1" respectively) as well as the CG (3 1/2" back from the leading edge of the wing). The Electrifly 1500 mAh LiPo is a snug fit in its tray, but I followed the recommendations in the instructions and cinched it down with a removable 8" Velcro strap. Fiddling with the receiver location and battery location finally netted me a CG right on the nose according to my Great Planes CG Machine (see the final locations of the components in the photo). I may experiment later on with relocating the servo arm clamps a bit closer to the axis since I had to turn the EPA down to about 45% for all the control surfaces. This will give me more servo throw and more mechanical advantage.

Don't forget to add the two additional included thin carbon fiber tubes which aren't mentioned in the manual, but which are used to stiffen the pushrods. You'll find them packed with the large carbon fiber tube used to stiffen the wing halves. Center them on each pushrod and hold them in place with a drop of CA at either end of the tube. I neglected to add them, which would later limit what I could do with the Yak on its maiden flight.

Let's go flying!

Flying

My club's president and I started off with a double check of the CG and the antenna orientation of the 2.4 GHz receiver. Given the Yak's light weight, he felt that the plane would fly better balanced somewhat more nose-heavy than the manual would suggest, and it turned out that his assessment was correct. All that needed to be done was to scoot the battery forward a fraction of an inch which did the trick. A bit of electrical tape provided additional insurance.

Moving on to an eyeball check of the control surfaces, Dan noticed that the elevator halves were slightly misaligned, easily fixed with some careful bending. The wingtips, however, had slightly different washout between the left and right halves. A heat gun would have pulled the low tip back up, but since none was on hand, we decided to tweak the wing at a later date if the washout became an issue, which it didn't.

A quick check of the rudder and elevator came next. Dan wanted to check whether or not the pushrods would flex under load and brother, were they going to flex. I found myself wishing the manual had mentioned those two little carbon fiber tubes which really were for eliminating the flex. Worse, I found myself wishing that I'd brought them with me to the field! In the interest of keeping the stress off of the rods and horns, we agreed that the test flights were going to be nice and simple, nowhere near the potential of this model.

He then suggested routing the antennas 90 degrees apart from each other as opposed to the 180 degrees I had them set at. One antenna remained routed along the inner wall of the fuselage while the second was taped next to where the canopy clips in. The reduced power range check was successful, so we were ready to fly.

Taking Off

President Dan did the honors of the maiden flight. The lack of a tailwheel certainly didn't keep the Yak from being able to be steered on the ground thanks to the gigantic rudder. It actually did steer with combinations of throttle bursts and lots of rudder, but it wanted to oversteer initially on takeoff. Dan was correct in stating that the plane would be easier to control on the ground with a little bit of up elevator applied while getting it rolling. Once the Yak gathered enough speed (which didn't take long at all), the tail became more stable, and off it went, requiring only a tiny bit of aileron trim to keep it on course. Until then, it was a delicate and slightly tricky balancing act of elevator and rudder to keep the Yak rolling at least reasonably straight until it began to ROG off the asphalt runway.

Basics

It became immediately apparent that the Yak is a very light model; the breeze that was blowing was enough to cause it to bob somewhat if flown too slowly into the wind, easy to do since this is not a fast plane but rather an aerobatic one. Throttle management in wind is important here, but don't worry since the recommended motor and prop have plenty of torque and yes, it'll go plenty fast as well when you throttle up. This system works for sport and light 3D flying, but a more powerful motor will be recommended (via Hobbico’s site) for full-3D performance. The really good news: Straight and level flight is a hands-off dream, as I found out later when I took it up. Even with ailerons which take up probably a quarter of the total wing area, neither of us had any problem banking the plane into turns. Only slight up elevator was required to keep it level. The ailerons respond quickly, so be ready. The relocated battery proved its worth during this time as well by keeping the Yak pointed straight ahead under high throttle application.

An outrunner-powered electric is a relatively silent beast; the Yak was no exception. It went through its paces with an almost ghostly silence, punctuated at times by the rush of air over the wings, especially in a dive. I was worried that such large control surfaces would be prone to flutter, but there wasn't so much as a trace. Only the turbine-like whir of the Rimfire outrunner and that rush of air on close fly-bys provided the soundtrack to our flights. Not only is this a quality model, it makes quality sounds!

One thing was certain, both of us were immediately comfortable flying the Yak, and both of us would have felt comfortable putting it through its paces if not for the pushrod issue. Even with self-imposed limitations, it was clear that this plane would do pretty much anything within any pilot's repertoire.

Landing

We also agreed that landings are exceptionally easy. Generous wing area and light weight make for a plane which can be landed almost at walking speed. In fact, I thought I'd slowed it down too much on my first landing, but rather than tip stall, the Yak floated right in for a textbook touchdown marred only by a very slight bounce on the mains. I wanted to land again, so off I went once more. I turned in to final from base and in she came, flaring out for a perfect three-pointer.

Aerobatics/Special Flight Performance

With the factory throw settings and a slight nose-heavy attitude, this plane will easily do anything you ask of it even if you base that assessment on our initial impressions with virtually no aerobatics whatsoever. I carefully attempted a brief knife edge, and it did so with no problems. Brief bursts of vertical performance were excellent as well, leading me to the conclusion that loops from straight and level flight were as close as the elevator stick. Increasing winds and the aforementioned lack of pushrod reinforcement shortened our time at the field somewhat. Needless to say, the first thing I did when I got home was to CA those tubes onto the pushrods. Bye-bye, flex. I also planned on picking up a Y-harness to run the aileron servos off of a single channel since this plane doesn't need flaperons.

The Yak and I returned to the field a couple of afternoons later, but the sun was in a really bad place to risk doing anything beyond some basic aerobatics. My first flight was nearly my last because of what turned out to be a bit of unnoticed down trim on the elevator due to the installation of the carbon fiber tubes. Even though the Yak came down kind of hard on the mains immediately after takeoff, there was no damage whatsoever. I limped the plane around the pattern and brought it in with relatively little drama. One of my fellow flyers with experience on a Futaba 6EX was on hand and he generously offered to help set the exponentials. I should also mention that he was very impressed by the trim scheme as was another flyer.

He began by reducing the all of the EPA adjustments even farther, thereby reducing the control surface throws to less than what the manual called for in hopes of mellowing out the flight characteristics. He then added 50% exponential to rudder, aileron and elevator. Finally, up went the battery pack even farther toward the front, with the edge of the pack now touching the rear of the motor box. A final check of the CG was performed and the Yak was ready for takeoff once more.

These changes literally transformed the model. ROG was as graceful as the real thing while the extra stick throw afforded by the exponential tremendously smoothed out the response. The twitch was gone, and in its place was smooth, fluid, locked-down control, probably the best I've ever flown. Even the top speed seemed much improved.

What wasn't improved in this particular configuration was the aerobatic response. Being careful to keep the Yak out of the sun, I attempted an Immelman turn which, while pinpoint accurate, was also way too big and slow as molasses with a roll rate far too slow for me to want to attempt inverted flight. My friend who'd helped me set up the radio reminded me that the high side of the dual rate switch had full throws and no expo, so I took the Yak up to a safe altitude before throwing the switch.

That simple motion turned the Yak from a lamb to the Tasmanian Devil. My first attempt at a turn nearly sent it into a snap roll. Once I straightened it out and regained something resembling control, I tried a forward loop and another Immelmann. No problem with either beyond extremely twitchy controls and a total lack of accuracy, which I'd expected. Flipping the switch back immediately tamed the controls, and I lined up for a landing. By then, the battery was extremely low, and I wound up landing just short of the runway, but the plane survived without a scratch.

Is This For a Beginner?

No. This plane, with its mid-mounted symmetrical wing, generous control surfaces and throws coupled with respectable airspeed is for a pilot with a pretty fair amount of previous experience, even tamed down with a computer radio. I'd considered flying it with a sport radio to provide a comparison, at least until I tried to fly the model with full throws and no expo. Those of you with some aerobatic experience are going to love wringing out this plane and those of you who are looking to expand your aerobatic skills will find this an excellent way to do so; it will simply do what you want when you want it to, but it will require some experimentation with exponentials.

Flight Video/Photo Gallery

Downloads

Conclusion

This particular Yak, unlike its much larger cousin, is late in coming to the Goldberg/Hobbico wedding party, but only for reasons beyond anyone's control. Now that it's here, I simply cannot recommend this model highly enough. It looks terrific, flies terrific, is of topnotch quality and, if assembled with topnotch electronics, is limited only by your piloting skills. I'm not embarrassed to admit that the Yak is a more capable plane than I am a pilot, but with a tool like this in the arsenal, I plan on bridging that gap much sooner than later.

Now's the time to have your hobby dealer order up a bunch of these magnificent models. Do make sure you get one for yourself. Hey, I don't want to be the only one out here with a Carl Goldberg Products Yak 54 EP!

Pluses:

  • Top-quality construction and materials
  • Ease of assembly
  • World-class flight characteristics
  • Outstanding performance with the recommended power setup
  • Support of one of the world's largest hobby distributors

Minuses:

  • The control horns are too small and require that too much material be removed to accept the pushrods (Hobbico is aware and is working to correct)
  • The box art claims that the model is glow compatible, but no instructions or accessories are provided
  • Some minor errors and omissions in the otherwise fine assembly manual
  • The tail doesn't quite fit as far forward as it should, easily fixed if desired
Last edited by Angela H; Dec 21, 2007 at 10:13 PM..
Thread Tools
Dec 24, 2007, 02:59 PM
Test your skills....fly IMAC!!
sun.flyer's Avatar
The review videos in there present format will require the download of the DivX video player to view if you do not already have this software on your computer.


Free Download

Tim
Dec 24, 2007, 03:01 PM
Pronoun trouble...
DismayingObservation's Avatar
Thanks, Tim. I now have another camera which will shoot in a more common format and with which I'll be shooting future videos.
Dec 24, 2007, 03:03 PM
Test your skills....fly IMAC!!
sun.flyer's Avatar
Quote:
Originally Posted by PMDrive1061
Thanks, Tim. I now have another camera which will shoot in a more common format and with which I'll be shooting future videos.
No problem bro!!

Nice work on the review. The picture of the Yak-54 with the mountains in the background is killer.

Tim
Dec 24, 2007, 03:24 PM
Pronoun trouble...
DismayingObservation's Avatar
Glad you liked it.

That was right after the mountains got a dusting of snow. Mount San Jacinto is slightly off to the right out of the frame and it got quite a bit of snow up at the top. I tried to compose the shot to get it in the frame, but I didn't like the result.

I'm very pleased that you enjoyed the review! It was as much fun to write as the plane was to build.

One of the things Great Planes is now looking into is a more powerful motor. The factory recommendation is good for straight and level and basic aerobatics, but it's a little bit underpowered for 3D. Great Planes will be adding addendums to the manual and to the kit itself based on this review.

I gotta tell ya...I really dig this plane. What a joy it is to fly!
Feb 27, 2008, 09:37 PM
Pronoun trouble...
DismayingObservation's Avatar
UPDATE:

Made one very simple change to this magnificent plane which more than woke it up. I ditched the 11x4.7 prop for an 11x7. I was going to try an 11x6, but the hobby shop was out of stock.

It literally transformed this plane.

The motor has no trouble whatsoever swinging this prop; it's rated for up to a 12x6. With this 11x7, it virtually leaps off the runway. Top speed is considerably faster, vertical performance is unaffected, aerobatics are easier overall thanks to the extra grunt as is flying into the wind and the runtime hasn't suffered in the least. Heading into the wind doesn't seem to slow it down whereas it wanted to virtually fly backwards when heading into the wind with the old prop.

Believe me, this plane has become my first choice in the collection of electrics.
Mar 11, 2009, 12:10 PM
Pronoun trouble...
DismayingObservation's Avatar
Good news. I'm still flying this model on a regular basis more than a year after my last entry. My conservative estimate is 100 flights and boy, my aerobatic skills have really sharpened up thanks to this marvelous little Yak.

I've only had to make one repair. It blew off of a table in the club's pit area due to a sudden gust of wind, shattering the motor box. I put the puzzle back together with some epoxy and reinforced it with some dowel stock. Some of the pinstriping has lifted off during flight, but it tacks right back down with a covering iron.

Other than that, a swap to a Castle Creations Phoenix-25 ESC, swapping the aileron servo arms 90 degrees to better line up with the control horns and a new APC 11x7 slow-flyer prop, it remains 100% as tested and as nice as the day I finished assembling it.
Last edited by DismayingObservation; Mar 11, 2009 at 12:23 PM.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Article Hobby Lobby New Power Modelisme's YAK-54 Tranchant ARF Review sun.flyer 3D Flying 21 Mar 22, 2015 02:52 AM
Article Carl Goldberg Products Skylark 70 ARF Review tailskid2 Beginner Training Area (Fuel) 14 Apr 17, 2010 04:21 PM
Article Ultrafly Models Yak-54 Balsa ARF Review 78dave Sport Planes 22 Dec 09, 2008 12:44 AM
New Product Carl Goldberg Products Pitts Monster EP ARF Jim T. Graham Product Announcements 0 May 16, 2007 12:30 PM
Discussion **NEW** Carl Goldberg 67” YAK 54 ARF Jim T. Graham Product Announcements 1 Sep 01, 2006 11:20 PM