RCU Review: Great Planes Dirty Birdy ARF

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    Contributed by: Geoff Barber | Published: July 2012 | Views: 38823 | email icon Email this Article | PDFpdf icon
    RCUniverse.com Review of Great Planes Dirty Birdy ARF
    Geoff Barber

    Email Me

    Great Planes
    Model Distributors

    2904 Research Road
    Champaign, IL 61826

    If you're familiar with pattern planes, especially senior pattern, you've heard of Joe Bridi and his many different designs. One of his most noted designs was the Dirty Birdy, which came to be in 1978. Over the years, this plane has been a staple on the pattern circuit, and definitely has a 'cult'-like following. The Dirty Birdy was designed to fly the numerous patterns in a graceful manner - and it does this well!

    I have always been drawn to the classic lines of planes like the Dirty Birdy. Long, lean, and smooth are three of the best ways to describe these planes. But, as of late, I have had ZERO time to build a kit! So when Great Planes announced they were releasing an ARF version of this classic design, I jumped at the chance to review it! Powered by the O.S. .65AX, I'm sure she'll be a real blast to fly!

    So, without wasting another second, let's open the box!

    • Balsa,Light Ply and Fiberglass Construction
    • MonoKote Covering
    • Classic Dirty Birdy Styling
    • Fiberglass Fuselage and Cowl
    • Fast, Easy Assembly
    • Great Color Contrast Between Top and Bottom of Plane

    • None as Tested

    Skill Level:

    Time Required to Build:

    Frustration Level:

    What do these ratings mean?

    Name:Great Planes Dirty Birdy ARF

    Price: $299.97 (Accurate at time of review)

    Stock Number: GPMA1975

    Wingspan: 64.5" (1640mm)
    Wing Area: 690 in² (44.5 dm²)
    Weight: 7.5-8.5 lb (3,400-3,850 g)
    Wing Loading: 25-28 oz/ft² (76-85 g/dm²)
    Length: 56" (1,420mm)
    Center of Gravity (CG): 5-13/16" (148mm) from the leading edge of the wing
    Radio Used:Futaba 7C
    Servos Used: (5) Futaba S3004 Servos.
    Channels Used: 4 total - Elevator, Aileron, Throttle, Rudder

    Control Throws: LOW

    • Elevator, up/down: 5/16" (8mm)
    • Ailerons, up/down: 9/32" (7mm)
    • Rudder, right/left: 1-3/8" (34mm)

    Control Throws: HIGH

    • Elevator, up/down: 1/2" (13mm)
    • Ailerons, up/down: 7/16" (11mm)
    • Rudder, right/left: 1-7/8" (48mm)

    Items Needed To Complete

    • 4-channel radio (min) w/ Receiver
    • .60 - .65 2-stroke Glow Engine
    • CA Glue
    • 30-minute Epoxy
    • Hobby Knife
    • Drill and Drill Bits
    • Thread Lock

    The Dirty Birdy arrived well-packed in a very nicely colored box. The box had lots of great full-color pictures of the plane along with specifications and recommended equipment information. There is a relatively low parts count, so I'm hoping it won't take me long to get it assembled!

    There were several features that I really liked about the Dirty Birdy. The fiberglass fuselage and cowl are very well built - strong and light - and the paint matches very well with the Monokote covering. The balsa-sheeted foam wing is very sturdy, and also has provisions for retractable landing gear. There are wheel wells pre-installed in the wing, along with hardwood rails on which to mount the retracts.

    Since the wing is set up for retracts, the included landing gear is designed to be installed like retracts. The plastic mounts are a very nice touch! There are two belly pan pieces included, along with a nose-gear wheel well cover. All three pieces are painted plastic, and look very nice.

    For this review, I'll be using a Futaba R617FS 2.4 gHz receiver, five Futaba S3004 Standard ball-bearing servos and a Futaba Y-harness. A Hobbico HydriMax 4.8 volt NiMh battery and two 12" servo extensions will also be used to complete the radio gear package.


    The included instruction manual lives up to Great Planes' high standards. The illustrations follow the written instructions, and though the Dirty Birdy is not a beginner's plane, any novice could assemble it without any trouble.

    Wing Assembly

    Assembly started with installing the aileron servos in each wing half, which were easy due to the 'surface mount' installation. I turned a clevis onto each of the aileron pushrods, and attached a control horn - this made it easy to line up, mark, and install the horn. Cutting the pushrod to length, adding a 90-degree bend and installing the FasLink completed the servo installation.

    The wing joiner is VERY stout when epoxied together - it consisted of an aluminum joiner sandwiched between two light ply pieces. Once the epoxy had cured, I test-fit the joiner, secured the anti-rotation pin in the trailing edge of one wing panel, and glued the two wing halves together with 30-minute epoxy. Reviewer's note - I add strips of masking tape 1/16" in from the root edge of the wing. This makes cleaning up the excess epoxy much easier!

    Using the landing gear mount as a guide, I drilled the attachment holes. The mount was then removed, the four holes were threaded with a screw and a drop of thin CA was added to each hole to harden the threads. The mount was installed, followed by the landing gear wire which was secured with two plastic straps. Flat spots were then filed on the landing gear, and the wheel collars and wheel were secured. Be sure to add a drop of thread locking compound to the set-screws in the wheel collars to keep them tight!

    Wing and Belly Pan Installation

    To install the fore and aft belly pan pieces, the wing was attached to the fuselage. With the wing in place, I traced each piece with a fine, felt-tipped marker, removed the covering from the marked areas, and glued both pieces in place using medium CA. This completed the wing assembly!

    Horizontal Stabilizers, Pushrods, and Elevator Servo Installation

    Since the fin is part of the fiberglass fuselage and the rudder is pre-hinged, the tail needed only minor assembly! The elevators are also pre-hinged (and glued), so it was easy to finish. I lightly sanded the stab and fuselage mating surfaces, slid the two carbon fiber rods through the fuse, and epoxied everything together. Once the epoxy had cured, the control horns and pushrods were installed in the same manner as the ailerons.

    The elevator halves are independent, requiring a mechanical connection inside the fuselage. The two pushrods are connected using a pair of wheel collars just behind the servo arm. This was easy to set up following the instruction manual!

    Rudder Servo and Pushrod Installation

    The rudder servo and pushrod installation was straight forward, as well, following the instructions. For a narrow fuselage, I was impressed by how quick the installation went!


    The three-line fuel tank was assembled and then mounted behind the firewall. A piece of the included 1/4" balsa stick held the fuel tank in place - the neck of the tank extended through a hole in the firewall.

    I then installed the engine mount using the included hardware. Again, I used thread locking compound to keep the mounting hardware tight.

    After installing the engine mount and marking the engine's location using my Great Planes Dead Center Tool, I removed the engine and drilled and tapped the engine mounting bolt holes.

    O.S. .65AX Spotlight

    A first-rate choice for trainers, sport planes and scale aircraft! It mounts in the same space as the 61FX ABL for easy drop-ins, weighs 1.9 ounces less than the 61FX, and features a newly designed 61D carburetor with angled needle valve!

    Key Features

    • Type: 2-Stroke
    • Bore: 0.95 in (24mm)
    • Stroke: 0.93 in (23.5mm)
    • Displacement: 0.65 cu in (10.63cc)
    • Practical RPM Range: 2,500 - 16,000 rpm
    • Weight: Without muffler- 17.5 oz (497 g)
    • Practical RPM Range: 2,000 - 17,000 rpm
    • Prop Range: 12x6 - 14x6
    • Fuel: 5% - 20% Nitromethane
    • Cylinder Type: ABC
    • Carb Type: Barrel, 2-needle
    • Crank Type: Ball bearing

    Download the manual in PDF format - Click here

    The throttle servo was installed in front of the elevator servo using the hardware included with the servo. Using a long 3/16" bit, I lined up and drilled a hole in the firewall for the throttle pushrod guide tube - the tube was secured to the firewall using a few drops of medium CA.

    The pushrod was then installed, and with a little bending, moved freely in the guide tube.

    Final Touches

    The nose gear was assembled and installed next - I did find that the wire gear leg was a tight fit in the engine mount, so I opened the holes up a little with a slightly larger drill bit. A second hole was drilled to allow the steering pushrod passage through the firewall. The pushrod was then connected to the rudder servo and the nose gear.

    Since I am reviewing the Dirty Birdy with fixed landing gear, I used a few drops of medium CA (SPARINGLY) to secure the wheel well cover in place. I may end up adding retracts at a later date, so I wanted this cover to be removable in the future.

    We're almost done! The receiver and battery pack were secured using pieces of the included 1/4" balsa stick - In the first picture, you can see that the battery is installed inside the canopy section of the fuselage. After some careful trimming, the cowl was installed followed by the propeller and spinner.

    Now it was time to balance the plane. To get the Dirty Birdy to balance at the recommended center of gravity (CG), I had to add 6 ounces of stick-on lead weight to the tail. I also balanced the plane laterally by putting 3 16-penny nails in the left wing tip. This was done by drilling 3 holes, countersinking the holes and pushing the nails into the wing. Once the nails were in place, I simply covered the holes with a strip of red MonoKote.

    That's it! With assembly completed, I charged the transmitter and receiver batteries and headed to the field!

    As luck would have it, the Alexandria (MN) R/C Flyer's club was having a fun-fly/swap meet on the nicest day of June! I had planned on going to the event anyway, but I always love being able to bring my newest review products out for all to see - the Dirty Birdy did not disappoint! This plane got so many "Oohs and Ahhs" and "I can remember flying one of those in the 70's/80's"!!!

    Since the O.S. .65AX was brand new, I decided to run a couple of tanks of fuel through it on the ground. A crowd gathered the first time I started the engine! When the plane was finally taken off the starting stand and taxied out to the runway, there were a lot of fellow pilots watching. I must also say that the ground handling was excellent!

    As the throttle was opened up, the plane rolled down the runway and lifted off very smoothly - there was no launch or jerkiness, only smooth action as though rolling up a ramp to the sky!

    A couple of circuits were made around the pattern to trim out the plane - just a few clicks of right aileron and up elevator were needed.

    The Dirty Birdy was flown a little while longer just to get a better "feel" for her, then brought in for the first landing. For a plane with a fairly high wing loading, I was very impressed by how well she slowed down! Just like the take-off, landing was easy and smooth!

    After checking the plane over and re-fueling, I had my buddy Jim Buzzeo fly the novice SPA routine while I shot the video for this review. Jim flew pattern "back in the day", so this was a real treat for him! I think the video speaks for itself as to the smooth flight characteristics of the Dirty Birdy!!!

    After his flight, Jim said to me, " Oh man, did THAT bring back a lot of good memories!!!" 'Nuff Said!

    For those of you that follow SPA, you'll notice an extra fly-by at the end of Jim's flight - I asked him to add that pass so the slow flight performance could be caught on video... So please, no "there were too many passes at the end of his routine" comments! :)

    Great Planes Dirty Birdy ARF

    The Dirty Birdy is one of those classic planes that will never go away, and thank goodness for that! The new Great Planes' version offers easy assembly, and the smooth flight characteristics of the original. This is one sweet bird that WILL be coming to the field with me a lot! Thank you to the folks at Great Planes/Hobbico for the opportunity to review this fantastic pattern plane!

    And, as always, Happy Landings to all of you!

    Great Planes
    Model Distributors

    2904 Research Road
    Champaign, IL 61826
    Website: www.greatplanes.com

    Futaba Corporation of America
    Distributed by:
    Great Planes Model Distributors
    P.O. Box 9021; Champaign, IL 61826-9021
    Website: www.futaba-rc.com

    O.S. Engines
    Distributed through
    Great Planes Model Distributors

    2904 Research Rd.
    Champaign IL 61826
    Phone: (217) 398-8970
    Website: www.osengines.com

    Comments on RCU Review: Great Planes Dirty Birdy ARF

    Posted by: angelrcdesign on 08/13/2012
    wow old mem, that was my first plane 1979 great flyer.
    Posted by: angelrcdesign on 08/13/2012
    wow old mem, that was my first plane 1979 great flyer.
    Posted by: KLXMASTER14 on 09/02/2012
    Nice job on the video. Nice to see actual pattern flying.
    Posted by: atron on 06/03/2013
    That plane/engine begs for a pipe!!!
    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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