Ultrafly Model's Decathlon Electric ARF Review

New author David Vaught weaves old memories of flying a rag covered plane by building and flying Ultrafly's newest European release.

Ready for the first flight.

INTRODUCTION

Ready for the first flight.
Ready for the first flight.
Wingspan:43.3 in"
Wing Area:2.1 sq. ft.
Weight:24.6- 27.1 oz.
Length:31.9"
Wing Loading:12.9 oz/sq. ft.
Servos:HiTec HS-55 & HS81
Transmitter:HiTec Optic 6
Receiver:GWS Naro
Battery:Thunder Power 11.1v 1320 MaH
Motor:Ultrafly Frio 9
ESC:Apollo 25 amp
AMP/Watt Draw:10 Amps/95 Watts
Manufacturer:Ultrafly
Available From:Ultrafly

When I heard Ultrafly Model had released a Super Decathlon in Taiwan I contacted them directly to get one. I was told they will soon have this model available in their European network of distributors, but I did not want to wait. It really did not cost much more, and they even included insurance.

When it arrived it kindled some old memories. In the 1980’s when I was getting my private pilot’s license my instructor asked me if I wanted to ride in the airport’s Citabria. Having defied gravity for the most part in a Cessna 150, I had never flown a taildragger, much less a tandem seat aircraft. The difference was amazing. I was not surrounded by aluminum and upholstery, but rather steel tubing and fabric and a full shoulder harness with a parachute as the seat cushion. A few loops, rolls and some inverted flight and my lunch seemed destined to experience zero gravity right next to me, but somehow I managed to avoid a ground cleanup.

The Super Decathlon is a derivative of Bellanca Aircraft’s Citabria of the 1960’s and has a rich history with far too much detail to give here. Ultrafly’s Super Decathlon is exemplary of a reproduction meant to make many of us more than willing to invest in this sport and to relive so many experiences of years past through RC.

KIT CONTENTS

Ultrafly’s Decathlon is a balsa covered ARF. It arrived well packaged and without any shipping damage. I was impressed with the simplicity of the manual, even though a few loose translations were present. Diagrams easily clarified what to do and when each step needed to be accomplished.

The “wow” factor was definitely present as soon as I opened the box. The covering was bright, well-shrunk and without any bubbles. As soon as I reviewed the manuals' list of materials, I realized the completeness of the kit.

No building is required for the wings, empennage or fuselage. Ultrafly has done a great job of actually making an ARF live up to the classification.

Kit Contents:

  • Pre-covered one-piece 43" wing with aileron servo cut-out
  • Pre-slotted and trial fitted ailerons, elevator and rudder (fiber hinges)
  • Pre-painted and drilled cowling
  • Pre-covered flat (non-airfoiled) tail and horizontal stabilizer with elevator and rudder pre-fitted
  • Prop - 9x7 - plus spinner, prop adapter and necessary hardware
  • Pre-painted wheel pants
  • Aluminum gear strut
  • Lightweight main wheels and tail wheel
  • Linkages and control horns
  • Battery compartment with locking cover and pre-installed battery Velcro strap

Additional Parts Needed:

  • Ultrafly’s Frio-9 KV-950 outrunner brushless motor
  • Ultrafly’s Apollo 25 amp programmable ESC
  • Hitec HS-55 servos
  • Eflite S75 Aileron servo
  • 11.1 3-cell Lipo x 1350 Mah
  • GWS Pico 4-channel receiver
  • Hitec Optic 6 transmitter
  • 6 inch servo extension

Assembly

It goes without saying that some ARF’s require more build time than others. Overall, I spent about six hours doing the build, with an additional two to three hours for the servo and electronics setup. Because I have an affinity for this plane, I really took my time.

As an overview, I just want to say that I am excited by Ultrafly Model’s sense of quality. I have flown their foamies with much satisfaction and was confident that these balsa aircraft would be just as good if not better. From the moment I received the plane I was impressed. Nothing I experienced through the building process frustrated me or seemed unnecessary. They have done nearly all the work, so I can fly. Parts fit perfectly, holes matched up, covering was well done, paint was high gloss and smooth and the completed airplane looks great. So many times over the forty years I have been building airplanes I have had to engineer my own way of getting something done. That, I assure you, is not the case here! You will get what you see and more importantly what you want.

Want more details on the build? Read on for specifics, highlights, and more. I won't rewrite the entire instruction -- a perfectly good manual comes with the kit! But here are the areas I found most interesting and worth pointing out.

WING AND EMPENNAGE

The wing is a flat-bottom dihedral type with ailerons running the length of the wing. About one-third of the front wing chord is balsa sheeted to improve strength. The wing roots are completely balsa sheeted. There were no warps in the wing and perhaps even more important, the ailerons were straight without any warps or crowns.

I was thoroughly impressed with the hinge slots and the process to attach the control surfaces. Every hinge was perfectly in line and after slipping the control surface onto the hinges, all I had to do was bleed a little CA onto the hinge.

I did have to add a small lite ply servo mount reinforcement for the ailerons on the underside of the wing.

An extension for the servo is recommended to make removal of the wing easier.

Installing the horizontal stabilizer into the fuselage after removing the extra material at the rear of the slot was easy, and the horizontal alignment was perfect. The instruction provides for a mark on the tail surface prior to installing that helps with the alignment.

Installing the vertical stabilizer was just as easy, but here I chose to use 5-minute epoxy because there was a slight starboard lean that I was able to hold straight with tape while the glue dried.

Ultrafly should be commended for keeping their quality control up -- a misaligned linkage can create problems, but these were perfect. While I did not do this, you could also melt the tip of the control horns that protrudes through the control surface to create a flat retainer so the control horn could never break free.

FUSELAGE

There is really nothing to say here. No building is required. The fuselage is well built of laser-cut balsa and lite ply and every joint that could be seen was precisely glued. I was amazed that the windows were perfectly glued with no marks, scratches or glue showing. The window canopy is attached with screws.

The only change necessary that was not mentioned in the instructions was the need to clear the rearward end of the horizontal stabilizer slot. A few quick cuts with my razor knife got this done.

LANDING GEAR AND WHEEL PANTS

The landing gear is made of aluminum and is pre-bent and pre-drilled. The wheel pants are pre-painted and even though the manual indicates you need to install a lite ply brace inside the wheel pant, the model I received had this step already completed. Mounting the wheels to the provided bolt was a little tight for me so I spent some time sanding out the inside of the hole to make sure the wheels were free to spin.

MOTOR MOUNTING AND COWLING

Once again I was impressed with Ultrafly’s attention to detail.

The firewall is well constructed and every joint is thoroughly bonded. Lightening holes are present and are handy for routing the motor wiring. Two large holes assist with cooling. The motor fit perfectly with the mounting holes pre-drilled.

The cowling fit perfectly as well. After the motor is mounted you can slip the cowling over the motor and install the prop and spinner. I used some tape to make sure I was aligned correctly and then installed the screws through the pre-drilled holes in the cowling.

RADIO, SERVO AND BATTERY INSTALLATION

This, too, was easy. I always test the direction of the motor with the ESC before installation. There is no dedicated routing for the receiver antennae. I routed mine down through one of the holes in the bottom of the fuselage. Because this plane is nearly 30 inches long and the measurement from the radio compartment to the end of the model is 20 inches, it is possible depending on the radio type that the antennae will not reach the back of the plane.

Completion

The battery compartment provides plenty of room to adjust the battery to obtain the correct CG. The instructions indicate 38 to 50 MM behind the forward wing bulkhead. All control throws were adjusted per the instructions with exponential of 30+ for the elevator, 15+ for the aileron and 10+ for the rudder. Finished weight with a 1350 Mah battery was approximately 700 grams.

FLYING

There is always a little bit of anxiousness just before the first flight. After following the provided directions for setting up the Decathlon I headed to the flying field, with just a touch of nerves. I need not have been...

What fun to fly! She looks so nostalgic, so majestic in the air.

One "problem" I soon realized was the Frio motor is so quiet that I really cannot hear the plane at all. I did not let her fly until the ESC cutout occurred, but I wonder if these old ears would be able to tell when that does happen.

A pleasant surprise is just how clean aerodynamically this plane is. It glides through the air. I was in a slight crosswind and I did recognize some buffeting as I flew, but because of the clean lines, headwind penetration was no problem.

Take-Off & Landing

I don't do ROG take-offs very often, so I chose to hand-launch. It was easy, uneventful. The Decathlon climbed and required little trimming. I kept it in the pattern to make sure everything was in order, and quickly enjoyed her performance.

When I decided to try an ROG, I hadn't even thought about the need to apply rudder to control prop torque. So that first attempt ended with a quick runway exit and a small cartwheel. On the next flight, the roll out was not pretty, but I did get it off the ground. It was a reminder that I need much more tail wheel practice. Applying throttle SLOWLY and being ready to add rudder before even starting out greatly improved the process.

Landings are a breeze. I try to do at least five or six every time I fly. Each one gets better! For landing, I always return my dual rates to low. At the conclusion of my first flight, I set up in the downwind and as I turned onto final I realized this plane was not ready to come down! I made three passes before I felt I was ready to touchdown. With no flaps I would say the landing speed is relatively fast. For a beginner, this can be difficult.

I wanted to keep the airspeed up to avoid a stall, so each pass I turned to crosswind further out. When I did land, it was uneventful and solid. The plane stayed down and rolled out perfectly. The landing gear is well built and handled every landing with ease.

Since the first flight I have flown the Decathlon several times. I have been perfecting my ROG takeoffs, but the small plane does have a habit of weathervaning with any wind at all. To compensate I reduce the rudder input and apply a slight amount of aileron into the crosswind.

As a testament to the durability of the Decathlon I have nosed it over many times with no damage.

Aerobatics, Special Performance

I did not wring the Decathlon out because that is not why I bought it. I have other planes designed for that. The Decathlon is about floating down memory lane, and easy aerobatics. This she did very well.

The control responses were adequate but I felt it flew better in the high rate configuration. It didn't act 'touchy' or difficult on high rates.

The power-off stall was very gentle with only a slight dip of the left wing. With a little head wind, I could not get the Decathlon to stall. The power-on stall provided a little more drop of the nose but still little wing drop.

I decided to work through a sequence of maneuvers. The loop was easy and straight with no tendency to slide out. The rolls were gentle and slow. With the setup provided by Ultrafly, even with the high rate, the rolls are very slow. Be careful to have plenty of altitude. Inverted flight was no problem, but again with the elevator in the suggested high-rate it took a full stop to hold the nose up during inverted flight. I liked the model's performance better -- it feels safer -- with increased throws, and might even consider experimenting with the CG a bit.

Flight Video Gallery

Downloads

Editor's Note: Please note that the video is of the model's first flights, on the lower throws. The model has become a bit more aerobatic with adjustments.

CONCLUSION

I definitely recommend this plane. I was pleased with the build, realism and performance. Ultrafly Model has done a great job of reproducing the Decathlon. I really have no problems with the plane and when/if it becomes available through a distributor you should put this on your next “to purchase list”. I will provide more input as I continue to fly this aircraft.

She is a joy to fly, as long as how she flies is what you want. What is important here is to remember the heritage of this airplane. It is not a Christen Eagle, Pitts Special or Extra, but rather an easy going, nostalgic, slow moving airplane that would very deliberately do whatever was asked of it, but with care. With a 150 HP engine, it was a finesse machine that did not even have an inverted flight fuel system.

Plusses:

  • Exceptional overall quality
  • Easy to build, much of the tedious work done for you
  • Great looking, excellent covering job
  • Solid, well built but not overly heavy
  • Lots of extras
  • Great flying, very scale
  • Builds within weight specifications
  • Everything fit with no need to modify
  • Built in battery compartment with locking door
  • Built in thrust angle

Minuses:

  • No flaps
  • No routing for the receiver antennae
  • Covering not removed at factory for joining areas
  • Had to remove block at trailing edge of fuselage for tail mounting
  • Tailwheel a little out of alignment
  • Control response too soft at stock settings and CG
Last edited by AMCross; Jan 15, 2007 at 09:36 PM..
Thread Tools
Jan 15, 2007, 05:49 PM
Registered User
diceco's Avatar

No symetrical airfoil


Gee.... To bad it's a flat bottom airfoil. I'd love to find an electric powered model of one of the classic shoulder wing airplanes (Super Cub, Taylor Clip Wing, Decathlon, Rearwin, etc) that has a symetrical airfoil. Then maybe it would do some real aerobatics.

diceco
Jan 15, 2007, 06:03 PM
Dr. Dave
diceco, I know what you mean, but it does do aer0batics. Nice, slow, gentle stuff. Real impressive. I heard one time a garage door would fly if it had a big enough motor. Touch and goes are great too. I am planning on upping the dual rates to see if it can do more. Just having a hard time changing it's character.
Jan 16, 2007, 12:17 AM
Hooper, full throttle!
Tommy D's Avatar
Hello Dave

Thank you for a very well written review. As I type this I have two of these models sitting in customs and I hope they will be delivered to me soon.

After purchasing and examining Ultraflys new FW-190 I knew the Super Decathlon would be a winner too. From all accounts the guys who took advantage of the group buy here in the USA are very happy.

Take care,

Tommy D
Jan 16, 2007, 01:45 AM
UAS Pilot - FAA# *******HRK
CryHavoc's Avatar
The Frio 9 on that 9x7 only drew 10amps? Did I read this correct?

Mike
Jan 16, 2007, 06:46 AM
Dr. Dave
Tommy D, I have an FW-190 as well that I am going to review. These are very well made planes with high quality looks. The FW is built and I am waiting for the weather to settle before I fly. It has a larger motor and I have a 2100 MAH battery. No issues at all with the build of that plane either.
Jan 16, 2007, 06:47 AM
Dr. Dave
Mike, I will check this again this evening.
Jan 16, 2007, 08:49 AM
The sky is my playground.
Dora Nine's Avatar
HOLY music there BATMAN!!
Jan 16, 2007, 03:04 PM
Registered User

NEWBIE Question


Dave,
The pic "thrust line" showing the top view of the engine mount area shows the left-hand side further out than the right. Is this a flaw or intentional?
One kit I have has this same apparent mis-alignment. Good thing I'm slow builder because I was actually gonna use a belt sander to make it flush!
I think I need a lesson on thrust line, any threads?
Craig
Last edited by OCFlyer; Jan 16, 2007 at 03:11 PM.
Jan 16, 2007, 03:31 PM
Fun Manager
AMCross's Avatar
Craig,
The thrust angle is intentional -- pointing the engine to the right and down (known as right thrust and down thrust). This counters the torque from the spin of the prop/motor, and is commonly done on aerobatic models to make them fly more precisely.

When the thrust angles and the wing/tail incidences (including the angle of the rudder hingeline to the fin) are done correctly, a model will fly 'absolutely true' -- no change in trim regardless of throttle setting or orieintation. The model will track straight on take off, it will stay straight when power is chopped suddenly such as going for a spin entry, etc. no climb/dive on throttle change; no roll change on rudder application, etc.

This post may help..
https://www.rcgroups.com/forums/show...e+#post6739919

Sincerely,
AnnMarie Cross
Publisher
RCGroups.com
Jan 16, 2007, 04:04 PM
Dr. Dave
OC Flyer, AMCross could not have said it any better. I would gues the trust angle is a common point based on engine testing. A large motor with a heavy set of magnets as in an outrunner might have a completly different set of thrust or P-Factors then say a geared inrunner. Also the size of the prop can create issues. When all is said and done the inclusion of the trusy angle does exactly what AMCross said and is is indicative perhaps of highly engineered aircraft that exhibit good flying characteristics.
Jan 16, 2007, 04:19 PM
BD Flyer's Avatar
Is this plane on their website yet? I couldn't find it.


Bill
Jan 16, 2007, 06:03 PM
Dr. Dave
No it is not because the website is operated by Hobbico and they are not importing the decathlon or FW-190 for Ultrafly. Perhaps TommyD can help here. Maybe send him a PM to see where he is getting his from. You can also contact Ultrafly directly.

rcsales@ultraflymodel.com
Jan 16, 2007, 09:22 PM
Hooper, full throttle!
Tommy D's Avatar
78dave

When you have a minute, could you PM me your E-Mail address. I have a question concerning the FW-190 build for you.

My Super Decathlon is in my workshop today. What a really nice little model!

Tommy D
Jan 16, 2007, 09:29 PM
RC Player
Megatech Man,
Ultrafly has 3 new model that is not on the current web site.
P-40 scale foam model airplane (93cm)
Super Decathlon 1.1M scale Hi-wing model
FW-190 Balsa 1.2M warbird
If you want these model, you can reach us by rcsales@ultraflymodel.com or join the group buy hosted by Tommy Dowling or go to the web site www.ohyesrc.com. Basicaslly Ohyesrc is a dealer in Taiwan. They carry all Ultrafly Products. You can sent email to them for items not on their web site.

Charlie

The new appointed distributor in the North America market is Model Rectifier Corporation (MRC). MRC will cover all dealers in United States, CANADA & MEXICO area. All dealers should contact them at 1-732-225-2100.

You can get the airplane at MRC after March!
Last edited by charlie2020; Feb 14, 2007 at 08:44 AM.


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