RCU Review: Extreme Flight Yak 54 - 74

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    Contributed by: Mike East | Published: December 2006 | Views: 57643 | email icon Email this Article | PDFpdf icon
    Extreme Flight 74" Yak 54

    Review by: Mike East Email Me

    Extreme Flight RC
    Distributed through Extreme Flight Radio Control
    3600 North Pkwy. Suite 101
    Cumming, GA 30040
    Phone: (770)887-1794

    Window Media Player
    Yak 54 ARF


    Easy Assembly:
    Covering Quality:
    Basic Flight:
    3D Flight:

    • Lightweight Contruction
    • Predrilled Robart Hinges
    • Nice Covering
    • Complete Hardware Set
    • Pre Installed Canopy Latch
    • Carbon fiber wing and stab tubes.
    • Removable Stabs

    • None!

    For the last few years Chris Hinson and the folks over at Extreme Flight have desgned and manufactured some of the best flying Yaks out there. From the electrics and profile to the famous 68" glow and 87" 50CC versions all have been proven winners at both 3D and IMAC. However the planes fly as light as a feather and with the low rate settings, they are about as gentle and easy to fly as once can ask from a scale aerobatic plane allowing realtively easy takeoff and landings and very stable flight.

    The lastest addition to the Extreme Flight family is no exception. This review will test the Extreme Flight Yak in the 1.40-1.60 engine, 74" wingspan version.

    Yak 54 doing what it does best

    In keeping with a tradition of excellence the 74" Yak is an engineering work of art with some of the best fitting and strongest laser cut structure you will ever see.

    It is also LIGHT which is critical in obtaining optimal 3D performance. Weighing in at an advertised weight of 10.5 to 12 lbs this plane should be an awesome performer with your 1.40-1.60 2 or 4 stroke engine.

    For this review I have chosen to shoot for "foamy power" by using the powerful YS 1.60 DZ as the powerplant. Let's get started and see what we find.

    This should be fun!

    Name: Extreme Flight Yak 54 74" ARF

    Price: $399

    Wingspan: 74 inches

    Wing Area: 1120 sq inches

    Length: 71 inches

    Flying Weight (advertised): 10.25-12 lbs

    Flying Weight: (actual) 11.5 lbs

    Engine: 1.40-1.80 2/4 stroke; Go to Extreme Flight RC website for electric details

    Engine Used: YS 1.60DZ

    Battery Used: Fromeco 2400mah Lithium Ion Battery

    Radio Used: Futaba 9ZAP

    Servos Used: Hitec 5955TG's

    Channels Used: 6 total - (2)Elevator, (2)Aileron, Rudder, Throttle

    Props Used:APC or wood 18x8,19x7

    Items Needed To Complete

    • 6 Channel Radio (Minimum) w/ 5 high torque metal gear servos and 1 standard for the throttle
    • (2) 18" Servo Extensions
    • (2) 12" Servo Extensions
    • CA Glue (Thin)
    • 30-min Epoxy
    • Various Standard Shop Tools

    The first thing that pops out whenever you recieve the Extreme Flight Yak is the packaging. The plane comes double boxed with a heavy duty shipping box to protect the contents inside.

    Upon opening the box you will immediately see that EF was not taking any chances on the contents being damaged. The entire contents is submerged in packing peanuts and everything is either individually wrapped in foam or heavy plastic wrap.

    Upon further inspection I found that the airplane was in immaculate condition. The covering was perfect everything was in pristeen condition. The highlights are a snap latched canopy that eliminates the need for cowl bolts, carbon fiber wing and stab tubes, removable stabs, and a truly complete hardware kit. Another significant find was that the control surfaces come predrilled for Robart hinges. Later on in the assembly we will have to glue them in place, but the simple fact that they are already drilled for us will save a significant amount of work.

    The hardware kit is about as complete as I have seen and contains quality hardware. Everything from the linkage assemblies to the landing gear shafts and wheel pants are first class equipment. Lets get started!!


    Click on the pic above to go to the manual.

    The manual is very concise and is designed for the intermediate to experienced ARF builder. Although it is more than enough information for a fairly experienced builder the writer assumes that you already have good basic assembly skills and knowledge of how to setup the airplanes engine and control surfaces. There are lots of pictures to help guide you through the process. All of the essential information that you need is there to successfully assemble the airplane and get it ready to fly.


    This airplane comes with some very nice and lightweight phenolic control horns. They are designed as a two piece horn and the pushrod linkage is connected in between to ensure propoer alignment and eliminate the risk of wear or breakage due to any side load on the horn.

    The slots for the horns are precut in the proper locations. All we have to do is locate the slots and cut them out. After the slots are cutout, place the horn in temporarily and mark the outline of the phenolic alignment plate. After marking remove the horn assembly and cut the covering away 1/8" inside the mark using an old soldering gun. You can use an X Acto knife, but you must be very careful to avoid cutting and weakening the balsa sheeting.

    Once the covering is cut away use 30 minute epoxy mixed with milled fiberglass and install the horns.

    Although at this point in the instruction manual the hinges have not been glued in permanantly yet, it is very important to ensure that the pivot point on the horn where the ball connector will be attached is centered directly over the center of the hinge line. Be sure to align properly and compare both elevators and ailerons and make sure the horns are aligned on the hinge line. You can see in the left pic just above that I compared the two sides to make sure not only that they were aligned on their respective hinge line but that the left and right are both in the exact same spot over the hinge line. If they are even slightly different you can end up with differential that will make it extremely difficult to match throws, especially on the elevators.

    The rudder horn assembly is similar to the other control horns. As with any rudder horn assembly, it is very important to make sure that both sides are aligned directly over the hinge line and that the distance from the pivot point on the control horn to the hinge is exactly the same on both sides. This is to ensure that you do not have built in differential.


    The Yak uses a standard Robart Hinge for all of the control surfaces. The airplane comes with all of the hinge points pre drilled and the hinges are temporarily set in place. All that is necessary for you to do is to lubricate the hinge before gluing and use either epoxy or an expanding glue like Pro Bond or Gorilla Glue to install the hinges.

    One thing I did want to mention is that the horzontal stabs are small and the distance from the hingeline to the stab tube is shorter than the Robart hinge. So be sure to clip off the hinge so that it does not push into the stab tube.


    The fuselage is a is a very lightweight, precision laser cut framed construction. I suppose I will mention the covering at this point. The covering is as nice as any I have seen. The scheme is beautiful and the covering was carefully installed. At a glance I can see no visible flaws or places that are loose.

    The key features are the pre installed canopy latch that eliminates the need for hatch bolts and the general completeness. Also the fuselage is very large and roomy despite the very light weight. There is plenty of room to get your hands in there and work. Very nice.

    Be sure to look the canopy over really closely. It is mentioned in the instruction manual and I found that there are a couple of place where the canopy is not attached to the formers, specifically the rearward canopy former. I used a thin bead of silicon to set the cowl in place where it was loose. I do not think I added anymore than 1/2 oz of weight.

    At this point we might as well go ahead and install the stabs and get a look at the fit. As you can see below the stabs fit nicely on the provided carbon fiber stab tube. All we have to do is bolt the stabs in place with the provided hardware.

    To install the stabs, slide the stab tube into place, lineup the alignment dowel and slide the stab into place. Using the provided hardware and a drop of blue Loctite on each bolt, bolt the stab into place. Thats it! Now lets move onto the landing gear and tailwheel.


    The landing gear is a fairly simple straight forward installation. The landing gear block in the fuselage is supported by aluminum angle on either side. The bolt holes are predrilled in the landing gear, but you have to drill out the fuselage. Just be sure and line up the landing gear so that the bolt holes catch the aluminum angle brackets for maximum strength. Its really hard to miss, is you simply center the gear and use the landing gear as a drill guide you cannot miss.

    The wheel pants need to be finsihed up as well. There is a light ply square that needs to be epoxied to the wheelpant so that the alignment bolts have something to bite into. The instructions call for simply screwing through the gear and into the wood but I opted to install blind nuts inside the wheel pant and use 2 4-40 socket head bolts to secure the gear. I have never had a wheel pant come loose using this t echnique.

    The kit comes with the landing gear shafts, all you need to do is install the wheels according to the instructions. Be sure to grind off a flat spot for the wheel collar so that it does not come loose. I also used a drop of blue Loctite on the set screw.

    The final step was to use a Dremel to grind out the pant so that it slips down over the shaft and then drill 2 4-40 holes through the landing gear and wheelpants, install the blind nuts (or screws) and secure the wheel pant in place. Done!!


    The tailwheel is a nice lightweight carbon fiber design and is quick and easy to install.

    All you have to do is drill for the tailwheel guidewire in the rudder 2" back from the hinge line, drill 2 1/16" holes for the tailwheel and screw it down into place with the provided hardware.

    The only complication during this step was that the angle of the carbon fiber strut was a little steep and the guide wire did not line up with the brass guide in the rudder. I simply made a Z bend in the wire to get it lined up properly and the tailwheel installation was complete. Time to flip it over on its feet.


    The upper left hand picture shows the design location of the tank. The front former gets in the way of getting the tank onto the front tray as illustrated in the picture so to rememdy this all that you need to do is cut the former just behind the tank away to match the width of the tank and slide it into place and mount to the tray. Thats it!

    Now, I wanted the tank on the cg so that I would not get a cg shift as the tank emptied so I decided to do a modification to get the tank where the cg would remain constant.

    What I did was cut out a slot out of the rear support ply of the landing gear mount just wide enough for the tank to slip through. Once I had the cutout where I wanted it I fiberglassed the seam of the horizontal and vertical plates and I was ready to install the tank as shown in the picture to the far right above. All of this is solid plywood so the structure should hold up just fine, time will tell. Again, this modification is not necessary nor is it suggested by Extreme Flight. The tank is very easy to install in the stock location and will work very well there. I only did this by choice so that the CG would remain constant as the tank level decreases through the flight.

    Now, lets intall the engine!


    The engine installation was a simple straightforward process. First you mark the firewall centerline and then mark 7/32" to the right of the line for the thrust offset to get the engine to line up on the center of the cowl.

    Once that is done you mark out the engine mount footprint and drill the engine mount holes. The front of the engine thrust washer should be approximately 6.5" from the firewall. For this plane I decided to use a Hyde Mount "Firm Idle MK II". This is a vibration dampening motor mount that does not require a nose ring. It comes predrilled with 2 sets of mounting holes that will accomodate YS and well as several other engine brands.Its a very economically priced option at around $65. After a friendly discussion with Merle Hyde to be sure that I had the right mount for the job I feel confident that this mount is more than sufficient for the application.

    Once i had the engine installed on the mount I marked out the holes for the motor mount aligning it according to the vertical and horizontal lines I drew out on the firewall per the instructions. Once the holes were drilled I mounted the engine. I used nylon locknuts and #6 fender washers on the backside of the firewall to secure the mount in place.

    YS 1.60DZ
    YS 1.60DZ

    YS 1.60DZ 4 stroke Engine

    The long awaited YS 160DZ is now available. Prototype versions distinguished themselves at the 2004 AMA Nationals, winning six of the top ten spots in FAI aerobatics competition. Other YS 140L/140DZ engines captured eighteen top awards including first place in intermediate, advanced and masters class, making YS Engines the overwhelming choice. While your focus may be other than competition aeromodeling, the YS 160DZ delivers more horsepower than an engine in its class, either two or four stroke. Depending on your selection of aircraft, the YS 160DZ can power models up to eighteen pounds with outstanding flight performance. Propeller size ranges from 15.5x12 four blade up to 18x10 wide, and ideal RPM range is 8000 to 8500 for best flight performance. Recommended fuel is 20 to 30% nitro helicopter type for best results.

    Key Features

    • The same size/weight as the YS 1.40's
    • Easy Operation and Mounting
    • Non Pressurized System


    • Type:4 Stroke Glow
    • Displacement:26.33CC 1.60ci
    • Bore: 34mm
    • Stroke: 29mm
    • Cylinders: Single
    • Total Weight: 35oz with Performance Specialties Muffler
    • Engine (Only) Weight: 33 oz
    • Crankshaft Threads: 8x1.25mm
    • Prop Range: 15x11 4 Blade - 18x10 Wide
    • RPM Range: 2000 - 11,000 (optimal on the ground 8000-8500)
    • Fuel: 30% Heli or DZ fuel
    • Muffler Type: Pipe or standard muffler

    Download the manual in PDF format - Click here

    As you can see the instructions from Extreme Flight were dead on. The engine hit dead center of the cowl and the backplate of the spinner is just the right distance from the from of the cowl.


    Mounting the cowl was a snap. The first step is to epoxy the plywood mounting blocks in place in the prepared slots.

    Once the mounts are dry simply slide the cowl into place and locate the proper location for the 4 mounting screws. Once I had the screws in place, I removed the screws and hardened the screw holes with thin CA. I also CA'ed the edges of the mounting holes in the cowl carefully from the inside to prevent the edges of the paint from chipping over time. The last step in mounting was to slip a short piece of fuel tubing over each screw to dampen some of the vibration and prevent it from wallowing out the screw holes in the cowl over time.


    The servo and linkage installation was a very straight forward process. All of the linkage hardware including pushrods, ball connectors and even the pull pull is provided for you. All you have to do is cutout the covering and seal the edges of the servo bays and install the servos. Once the servos are in place just connect the servos to the control horns and setup the linkages for the desired throw.

    As you can see in the last picture, since I relocated the tank I used the tank tray as the location for the receiver and battery pack. I simply placed the receiver and battery packs in the necessary location to get the CG where I wanted it and used Fromeco velcro tie downs from www.fromeco.org. We are done!! Lets go take a few posing shots and give her a fly!

    It was immediately apparent that this was a serious 3D machine and very well designed. From the moment that the plane left the ground it felt responsive and as light as a feather. Takeoff was as easy as the most docile of trainers and landing was equally as gentle.

    Everything I have ever heard about the equisite performance of this plane was fact. This baby is built for raddical 3D and yet is incredibly stable not only in low rate flight but also in high rate 3D "mode". The thing that immediately jumped out at me was how the airplane simply does what you ask it to do. It does not have strange tendencies that lend itself to snap unexpectedly. You can putter around in a harrier without worry of the plane unexpectedly snapping into the ground for no apparent reason. If you pull/push hard full up it stands right up into a wall without dropping a wing. Similarly but not surprisingly this was also true for parachutes. Inverted or upright!

    Rolling maneuvers, especially in high alpha were really nice. It did require the full high rate deflection of ailerons to harrier roll, probably because I was using an 18x8 prop. The 1.60DZ would probably do better with a 19x7 or 20x4/6 and provide a lot more propwash for good aileron response in a post stall attitude.

    Precision flight was good, but not great at a 6 5/8" cg. This because I used a Tru Turn lightened backplate and a light weight wooden propeller that made it difficult to get the cg back up to the 6" mark. In defense of the plane, think that I might have had the CG back just a little too far. Bad for IMAC, GREAT for 3D and the plane "hunted" just a little as a result. Another thing that made me believe that I had the plane too tailheavy for precision flight was the fact that the plane climbed when inverted and tucked pretty significantly to the wheels in a power off vertical downline due to a little extra down elevator trim I had to use to get the plane to fly level. The suggested 6" cg should do the trick in correcting that issue, I suspect with no significant effect on the 3D performance.

    Overall I will give the plane a solid "A". It "feels" and performs like its giant cousins, but at a fraction of the cost.

    Check out the video to see her in action!

    Broadband 30 MB

    Broadband 22.4 MB
    Dialup 4.87 MB

    Let me just say that this plane was a real pleasure to review. From the time that I opened the box and found every piece there and in good shape to the actual performance of the plane it was a really good experience.

    There is really nothing critical that I can think of to say about this plane. Everything fits perfectly, and is quality made. The airplane flies exactly as advertised and then some. From the quality of the covering, to the frame up, to the quality of the hardware this is a 1st class piece of equipment.

    If you are looking for a Yak that performs similarly to its 40% big brothers but at a fraction of the cost then the Extreme Flight Yak should be just right for your needs.

    Extreme Flight Radio Control
    3600 North Pkwy. Suite 101
    Cumming, GA 30040
    Phone: (770)887-1794
    Website: www.extremeflightrc.com

    Futaba Radios
    Distributed by:
    Tower Hobbies
    PO Box 9078
    Champaign, IL 61826-9078
    Phone: 800-637-6050
    Website: www.towerhobbies.com

    YS Performance
    PO Box 3146
    Gardnerville, NV 89410
    Phone 775-265-7523 (Information)
    Website: www.ysperformance.com/

    Performance Specialties (Mufflers Etc.)
    PO Box 3146
    Gardnerville, NV 89410
    Phone 775-265-7523 (Information)
    Website: www.pspec.com/

    Central Hobbies
    1401 Central Avenue
    Billings, MT 59102
    Phone: 1-800-723-5937
    Website: www.centralhobbies.com

    email: chobbies@centralhobbies.com

    Comments on RCU Review: Extreme Flight Yak 54 - 74

    Posted by: wallace.tharp on 11/29/2011
    I own one with a YS-140. they fly grat but are a little flimsy, easy to knock the gear off etc. Kind of build like with kite sticks. Really light! wallace tharp
    Page: 1
    The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review.

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