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The QQ YAK 54 35CC ARF is the foundation for the Best Medicine project plus it will be a full review and flight test subject as well
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Flex Innovations QQ YAK 54 35CC ARF

The subject of my Best Medicine Project

Text, photos and video by Tom Hintz

Posted – 5-3-2017

To help me deal with a doctor-prescribed one to three-month grounding following chemo, radiation and six hours of cancer-busting surgery I needed to come up with something to keep working in the shop interesting. I came across the QQ YAK 54 35CC ARF almost by accident while looking for a new hyper-active airframe. I noticed a big ad for Flex Innovations that showed the QQ YAK 54 35CC ARF gasser I did not know they were making. It uses a 35cc engine which is exactly what I needed and it was designed by Quique Somenzini so how could I go wrong?

The QQ YAK 54 35CC ARF will make a great foundation for a full-on Review plus a bunch of related How-To stories so many of you have been requesting. Watch at the end of this Review segment for a listing of the How-To’s and Reviews that were produced with the QQ YAK 54 35CC ARF.

I am realistic enough to know that folks like XFC Champion pilot Seth Arnold who flew the QQ YAK 54 35CC ARF for the “single-take demo video” (that’s just showing off!) just might be able to make a plane fart little red stars at the top of a pop up. My piloting skills are “somewhat” (dramatically) less than that. I look at these demo videos as testament to the capabilities of the airframe, not as a promise of what I will be able to do with it. I do think that the capabilities of the QQ YAK 54 35CC ARF will help me expand my abilities on the sticks but it is not going to do it for me. It helps knowing that you are practicing /learning on a very capable airframe.

The Basics

The QQ Yak 54 35cc™ is based on the uber successful Yak 54 series designed by Quique Somenzini, 4-time TOC Champion, F3A World Champion and produced by his company in the early 2000’s. The QQ YAK 54 35CC ARF represents the next generation in the QQ Yak 54 series. While the aerodynamic capabilities of the QQ YAK 54 35CC ARF are cutting edge, the construction using lightweight balsa, light plywood and carbon re enforcement promise a very straight and tough airframe. The QQ YAK 54 35CC ARF can handle the violence of extreme 3D tumbling yet turn into a near floater for landing.

The QQ YAK 54 35CC ARF Airframe (left) is very light but very rigid. The fiberglass plate (right) bonded to the firewall stiffens that area plus prevents the engine standoffs from sinking into the soft wood.
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The QQ YAK 54 35CC ARF has a wingspan of 76.0'' (1930mm) and an overall length of 75.0'' (1880mm). Set up with a DA35cc gas engine as we are doing the QQ YAK 54 35CC ARF should weigh in at 12lb 9 oz (5.7 kg) which is not at all bad for this large of an airplane.

Flex Innovation Aero-Tweaks

One of the most visible aspects of the QQ YAK 54 35CC ARF are the 'Shark Teeth' along the outer leading edges of the main wings. These “teeth” are designed to soften tip stall (and wing rock) during maneuvers like Elevators and high Alpha flight. The full-length aileron counter-balances offer high roll rates, even at lower airspeeds. These large counter balances dramatically reduce the load on servos. Custom SFG’s (side force generators) are included. The fuselage is oversized and gives the impression of a 50cc plane in the air. Plus, that enlargement at the cowl helps to keep most cylinder heads inside of the cowl.

I almost didn’t notice that the elevators have an approximately 1/8”-tall lip along the top of the trailing edges. We see these “wicker bill spoilers” in various forms of racing because they can greatly enhance the effectiveness of a surface but I have not seen this in an ARF. I pulsed Flex Innovations on these “elevator lips” and they said they are designed to reduce flutter at high speeds.

The control surfaces are assembled with hinges in place but not glued. I noticed that the gaps between control surfaces and the fixed portions are very small. Pay attention while gluing the hinges in place and you should also have tiny gaps that will enhance flight performance.

The slots in the control surfaces for control horns are trimmed and ready to be filled with the arms. Even the groove for the tail wheel wire that gets epoxied into the rudder is already cut from the factory and ready for installation. Flex Innovations is looking more and more to be very cutting edge in their design and ARF preparation.

The QQ YAK 54 35CC ARF comes with an extensive hardware set that lets you build a tough, dependable model right out of the box. All of the hardware appears to be first class pieces. The control horns are designed and sized to provide the maximum throw for the airframe but with a high level of precision. The fiberglass wheel pants and cowl come fully painted and the rest of the plane covered with genuine Oracover® so you can get the right covering to make repairs easy and virtually invisible.

Notice the lip on the rear of the elevator upper surface> (left) That helps prevent elevator flutter at high speeds. All of he control surfaces have full width counterbalances (right) that reduce servo loading substantially.
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The cowl is one piece with the faux grill work molded into the cowl itself. Also, the cowl is large enough that the cylinder head of the DA35 should stay within the cowl for a much cleaner, more aerodynamic look.

All of the openings in the airframe and covering for servos and cables are opened and the edges sealed at the factory. I will go over those to be sure but this is way easier than having to open them myself. I am liking this plane!

Because the QQ YAK 54 35CC ARF can be flown with gas or electric power the main hatch is secured with a rugged-looking single spring-loaded latch for quick, tool-free access. I am usually wary of these single spring latches but the one in the QQ YAK 54 35CC ARF is way better made than anything I have seen so far. You get formed aluminum landing gear as standard equipment but we will be using the optional carbon fiber main gear.

Another interesting feature of the power choice is a pair of equipment trays that make installation of the electric or gas equipment easy and even provides a fast way to remove all that equipment for repairs if need be. Forward equipment trays don’t get glued or wood-screwed into the structure. Either style is bolted to the airframe with threaded inserts already installed at the factory. A little blue thread locker and the radio gear is secure, yet can be pulled if need be for access to other things.

They even include a separate, nicely made battery tray that mounts below the rudder pull-pull the rear edge of the cockpit to help get the CG right for some potential engine combinations. This tray is ready to use with cut slots for hook and loop straps to secure the batteries. This tray shows that the folks at Flex Innovations want to make it as easy as possible for you to get the full performance available. Very nice touch.

Flex Innovations had a special offering add-on packages that saved money. I got the DA35cc engine package (left) and the electronics package (right) and saved a bunch of money.
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Something else that was totally unexpected was finding what appears to be a fiberglass plate bonded to the front of the motor box. Flex Innovations says this plate is meant to stiffen the motor box structure and eliminate the engine standoffs from sinking into a wooden surface. This plate and the motor box are pre-drilled for the DA35 so installation is a snap. The instructions even show how to lay out the firewall to drill for the DA35 throttle rod as well as the choke rod if you want to use a servo for that. More very nice touches.

A set of protective wing bags are included as is a decal sheet and a very well done, comprehensive printed manual. Flex Innovations also provides on-line support including updated instruction manuals that can be downloaded.

The optional ARF Combo Includes all of the standard components plus their Aura 8 - Advanced Flight Control System, 5 Potenza DS22209 Digital HV servos with (16 kg-cm (222 oz-in) torque, 0.09 sec/60° (@8.4 volts). They even provide the properly sized aluminum servo arms, 2 single arm 1 ¾”, 2 single arm 1 ¼” and 1 double arm (rudder) 1 ½” (radius) so we get the prescribed control surface throws the first time around.

I also added the optional ARF Gas Super Combo that includes a DA35 Gas Engine, DA35 Pitts Muffler and 1 Potenza DS22209 Digital HV Servo for the throttle. Aside from getting all the correct pieces in the box I thought this package had a good price on it. Everything in this upgrade is first rate.

Conclusions

To say I am impressed with the QQ YAK 54 35CC ARF would be an understatement. That means that taking my time and doing all of the related content this build will generate is going to be tough. I’d like nothing better than to go on a binge and get the QQ YAK 54 35CC ARF in the air. Between common sense and my doctors’ orders I will go slow and you will get all of the content this project can generate.

Video Tour

One of the deciding factors in using the QQ YAK 54 35CC ARF for this project was the value I saw in the overall package as I bought it. The QQ YAK 54 35CC ARF itself was $399.99 plus $99 flat rate shipping lower 48 states. I wanted to do a 35cc engine review and noticed the ARF Gas Super Combo Yak 54 35cc package for $1349.99 (4-24-2017) and by the time I added up the normal cost of all the pieces included I was ready and clicked the Buy button!

Stay tuned! This is going to be a fun plane to build and I get to produce a bunch of content to answer so many emails received during my cancer down time.

QQ YAK 54 35CC ARF related content:

Hinging Control Surfaces

Installing a Pull-Pull System

Installing Servos

Installing a Gas Engine

Installing Gas Tanks

Visit the QQ YAK 54 35CC ARF web page – Click Here

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