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Ultrafly Models Yak-54 Balsa ARF Review

Dr. Dave reviews the Ultrafly Models' Yak 54, the final in his trilogy of reviews of Ultrafly balsa aircraft.

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Introduction

Wingspan:47.24 in. /1200 mm
Wing Area:399.9 sq. in./25.8 sq. dm.
Weight:37.04 oz./1050 grams
Length:39.37 in. /1000 mm
Wing Loading:.093 oz/sq. ft. /40.70 g/sq. dm.
Servos:Cirrus CS301
Transmitter:Optic 6
Receiver:GWS
Battery:2200 Mah 15C EMax
Motor:Ulltrafly F/18/12 (350 watts)
ESC:Eflite 40 amp
MRSP:$142.98
Manufacturer:Ultrafly Model
Available From:Model Rectifier

This is the final in a trilogy of reviews of Ultrafly's high performance balsa constructed aircraft. Given the success of the Ultrafly FW-190 ARF Review and the Ultrafly Decathalon ARF Review I had no reservations about reviewing the Yak-54. I believe that you will be more than impressed with the construction and flight characteristics of this well designed and fully aerobatic aircraft.

According to MRC's website the Yak-54 "was specifically designed for extreme aerobatic maneuvers. Compared to most other small aerobatic balsa models which were developed using a direct scale duplication of TOC design, our specially designed thick airfoil provides much better lift for performing slow speed modern aerobatic maneuvers. The wing-loading of this airplane will match to many larger 60-120 size glow engine models. That is to say, you may enjoy a great flying performance with only a limited budget and forget about all that trouble of a glow engine model. Trust us when we say with our design you can ‘feel’ the difference!"

Kit Contents

The Yak 54 arrived with no damage and was well packaged as all the Ultrafly series of balsa planes have been. The box is colorful and provides excellent information for buyers.

I was especially impressed with the covering and the fiberglass cowling. The color photo manual with actual assembly pictures is a major change for Ultrafly. I have built almost every one of Ultrafly's planes, and this is by far the most advanced manual in their product line.

Kit Contains

  • Covered wings, tail and fuselage
  • Trimmed canopy
  • Wheels and wheel pants
  • All hardware

I was all pleased to see the first page of the instruction manual gave the exact requirements for setting up a sport model or a 3D model. This set of instructions was detailed down to the wattage and prop required for each flying style.

Kit Requires for Sport Flying

  • At least a 200 watt power unit
  • 11x5.5E prop
  • 3S Lipo 2000 mAh
  • 28 amp ESC

Kit Requires for General Aerobatics

  • Ulltrafly F/18/12 (350 watts)
  • 11x5.5E prop
  • 3S Lipo 2500 mAh
  • 35 amp ESC

Kit Requires for 3D Aerobatics

  • Ultrafly H/12/11 (390 watts)
  • 11x5.5E prop
  • 3S 3000 mAh LiPo
  • 40-50 amp ESC

I had both motors available to me for testing so I was able to make an informed decision as to which one was right for my style of flying. Both motors were tested using an 11x5.5E prop with a 2100 mAh x 11.1v 15C LiPo.

F Series
F Series
H Series
H Series
SeriesWattsAmps RPM Thrust
F 312 33 8300 3.4 lbs
H 260 25 7700 2.15 lbs

Given the bench test I decided to go with the F-Series motor. in spite of the fact the H-Series motor is the higher performance motor, I saved some weight with the F-Series, and decided to go with it. It is possible the battery I was using, being a 15C, was not capable of getting the full performance of the H-Series motor with the 11x5.5E prop. The instruction manual clearly indicates a 3S2P 3000 mAh battery is necessary for extreme aerobatics. The framed weight of the Yak without any electronics, battery or servos is about 1 lb 8 ounces. The AUW is 1150 grams (2.5 lbs) with the F-Series motor so I was, in theory, still capable of hanging on the prop within the general aerobatic maneuvers catagory.

Assembly

Because the cowling location and setup for 3D are critical, this kit takes a little longer to build correctly. You immediately realize the laser cut balsa construction is precise and deliberately cut and placed to make the Yak-54 as light as possible. The trade off in a lightweight airframe is weight and balance liberties with the size of the battery, motor and electronics.

Assembly of the Yak-54 was similar to other Ultrafly models with regard to the tail, but the wings are not glued in. They are held in place with wooden pins for stability, a carbon wing spar and plastic or steel wing bolts attached from the inside of the fuselage. You may have to slightly sand the pins down to make sure you have an intimate bond between the fuselage and the wing root. The canopy is completed so all you have to do open it. Strong magnets on both sides ensure a secure fit.

Wing

Wings just require the ailerons to complete. Hinges are fiber and only require a small amount of CA glue to secure them in place. I used T-pins to get a consistent spacing along he entire length of the wing before gluing. I also taped the ailerons in place.

Fuselage

You can tell the framework is well designed and structurally sound. The canopy fits perfectly and is tightly held by magnets on both sides. Once I had selected the motor I mounted it firmly in the center of the motor mount. I then mounted the cowling and measured several times the distance around the motor shaft and the cowling. Once I was comfortable with the motor shaft being centered in the cowl, I drilled the holes for the mounting screws. Make sure the canopy is on at the time because it slips under the cowling. If you mount the cowling too far back you may have difficulty attaching and removing the canopy.

Tail

Because this is a high performance 3D plane, I was careful with the alignment. I used 30 minute epoxy because I wanted to have plenty of time to double check the alignment. I needed to put a square on the vertical surface and hold it over as the glue set, and I used 5-minute epoxy because the trial fit was off a little and I wanted to hold it while the glue set.

For the elevator installation, I used pins to give me a clean straight gap and then glued with CA.

Radio Installation

Because the Yak is weight conservative and likely tail heavy I forced everything I could toward the firewall. I wanted to be sure I did not have to add any weight, and if I did I wanted it to be minimal. Moving everything forward included putting the ESC on top of the motor mount as well.

The battery needed to be moved forward as well and was forced into the motor mount and then surrounded by foam. I placed a small piece of wood behind the battery to hold it forward.

Completion

The set up was as prescribed by Ultrafly. There were two setup options, and both used a CG of 75-90 mm behind the leading edge of the wing.

Sport Flying

  • Ailerons = 8-10mm Exp:50
  • Elevator = 10-15mm Exp:50
  • Rudder = 15-20mm Exp:50

3D Flying

  • Ailerons = 25-35mm Exp:20
  • Elevator = 30-45mm Exp:20
  • Rudder = 50-70mm Exp:20

I adjusted my dual rates to provide the sport flying on the low rates and the 3D on the high rates. I had to increase the exponential on the high rates as I was not quick enough to keep up. More practice will improve my skills.

A final check of the CG at 80 mm required I add about 28 grams inside the cowling as far forward as I could get it.

Flying

The Yak-54 is one of the most solid performers I have flown. It is crisp, accurate in maneuvers and stable in flight. In flight the Yak tracks straight and stays straight throughout the maneuver. Doing four point rolls is easy. The symmetrical wing lets the Yak fly right side up of upside down with no regard for flight forces trying to make corrections. The Ultrafly F series motor coupled with the 2100 mAh LiPo provided plenty of power and flight time.

Basics

I am not a 3D flyer, but I can fly maneuvers and appreciate the way the Yak responds to my inputs. The plane is predictable and well balanced. Because of its quality engineering, design and construction, I think anyone dedicated to 3D will, without a doubt, be impressed with the versatility of the Yak.

Taking Off and Landing

Take off is almost like a F-15 Viking departure. The plane will lift off and climb straight up immediately. Landings are easy too, and with speed the plane will easily settle to the ground. Because the moment is so short on the Yak, be gentle on the elevator and use the throttle to your advantage. Gradually ease the throttle back, and allow the Yak to settle with speed to the ground. If you get to slow, you will stall, and it will be a tip stall that will be difficult to recover from quickly enough to avoid damage. The Yak though really does not differ from other planes in that regard.

Aerobatics/Special Flight Performance

What can I say? It does it all. The Yak is aerodynamically clean and flies with little drag. Point it up and it powers up, point it down and terminal velocity is achieved in seconds. I have flown many planes and none glide through the air like this one. In downward maneuvers, you have to be cognizant of ground zero because of its speed.

Is This For a Beginner?

I would have to say no for two reasons: it is quick and nimble, and it likes speed. Because of this combination, reaction times need to be fast and the only way to build those is through experience. When you do transition to your next plane, the Yak will be very friendly and make you look very good when you fly.

Flight Video/Photo Gallery

Downloads

Ultrafly Yak 54  9.68 MB

Conclusion

This is the final in the Ultrafly review trilogy, and I have loved them all. The quality of the construction is top of the line and its flight characteristics are superb. I hope you follow my lead and build a Yak-54 just like this one. If this is the first one of the trilogy you will want more, and if you have all the others, the Yak will be the crown jewel of your aerobatic collection.

Pluses

  • Well engineered
  • Clean aerodynamics
  • Great looking and well applied covering

Minuses

  • Plastic wing bolts easily strip
Last edited by Angela H; Nov 21, 2007 at 08:22 AM..
Thread Tools
Nov 20, 2007, 09:23 AM
Registered User
It likes speed ? Isn't this a 3D aircraft ??
Nov 20, 2007, 12:06 PM
ExtremeFlight - 3DHS - Legacy
blucor basher's Avatar
Better question - why is the review in RCPower instead of EZone?

I suspect it will move soon...
Nov 20, 2007, 12:37 PM
Registered User
Quote:
Originally Posted by blucor basher
Better question - why is the review in RCPower instead of EZone?
Better question ? No, maybe as good though
Nov 20, 2007, 01:58 PM
Administrator
Angela H's Avatar
Sorry! Bleary-eyed late night publish!
Nov 20, 2007, 02:43 PM
Timelord
Doctor Who's Avatar
Nice

Your runway looks a little challenging.
Nov 20, 2007, 06:17 PM
Dr. Dave
I know it looks tight but that landing was pretty much at my feet, I really have about 20 x 200 just never use that much since final is typically into the wind and with a little slope lift.
Nov 20, 2007, 09:17 PM
WOOOOsssSSSShhHH !!
sparrow1717's Avatar
Nice review.

Ive got one sitting in a box behind me

I gotta start my build soooooon.

Spar
Nov 20, 2007, 10:24 PM
Electrocuted
RC_AVIGATOR's Avatar
Where is the Ultrafly Decathelon review mentioned ---the ling seems broken and a search does not show an Ultrafly??
Nov 20, 2007, 11:02 PM
iumop ap!sdn w,I
G.P.'s Avatar
Thanks, I wanted to see a review of this plane.

Is the elevator installed upside down or does the covering on the elevator not line up on purpose? The rest of the scheme flows really well.
Last edited by G.P.; Nov 21, 2007 at 01:05 AM.
Nov 20, 2007, 11:54 PM
Registered User
Look much the same as HC Yak 54 45 slightly diff build..stronger..
Nov 21, 2007, 04:28 AM
Chillaxin dude!
BulletMaster's Avatar
yep.... elevator is upside down....
Nov 21, 2007, 06:36 AM
Dr. Dave
I must be an idiot. I had even read a review of the same plane and they had the tail on upside down. Sorry for that mistake I won't do it again I assure you. I think I was jinxed on this review. Not in reference to the plane or any components, but more to my flying. Maybe this was the omen I missed!
Nov 21, 2007, 06:39 AM
Dr. Dave
Here is the link to the decathlon. I tryed the links in the review and both go to FW-190

https://www.rcgroups.com/forums/showthread.php?t=604400

By the way that link has over 11,000 views!
Nov 21, 2007, 01:39 PM
iumop ap!sdn w,I
G.P.'s Avatar
Quote:
Originally Posted by 78dave
I must be an idiot. I had even read a review of the same plane and they had the tail on upside down. Sorry for that mistake I won't do it again I assure you. I think I was jinxed on this review. Not in reference to the plane or any components, but more to my flying. Maybe this was the omen I missed!
The top and bottom scheme look pretty similiar, so I can see how it would happen. It still looks good! -Greg
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