RCU Review: Great Planes Christen Eagle GP/EP ARF 42.5

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    Contributed by: Mike Buzzeo | Published: October 2011 | Views: 27560 | email icon Email this Article | PDFpdf icon
    RCUniverse.com Review of the Great Planes Christen Eagle GP/EP ARF 42.5"
    Mike Buzzeo

    Email Me

    Great Planes
    Model Distributors

    2904 Research Road
    Champaign, IL 61826

    Have you ever been looking at a group of airplanes and thought, "Is that an Extra 300, or an MX2?" or maybe "Sukhoi or Yak?" Sometimes it's difficult to tell one from another from a distance, but one glance at the distinguishing color scheme and the Christen Eagle is immediately identified.

    Looks wise, I've always been partial to the Christen Eagle over Pitts Specials or even the Ultimate 300. It breaks up the "Golden Era" look of the Pitts while not being as "Squared-off" as the Ultimate. But looks aside, like the others they can be a bit of a handful in the air!

    The short tails on these planes make for radical maneuverability, but this can easily bite a less experienced pilot if he is not familiar with short-coupled Bipes!

    Great Planes has recently introduced a new 42.5" version of this air show favorite. When I first saw this plane at Toledo I was immediately intrigued. It looked really good... REALLY GOOD, but as 46-size airplanes go, this one is rather small and, as you probably know, larger planes are more stable (which is a nice way of saying that smaller planes are LESS stable), so I plan to dive into this project with prudence. I can hear that little devil on my shoulder saying, "That little thing could bite you!" (Maybe that was part of the intrigue!) but I also have enough faith in Great Planes to know that they would not put an unstable plane in their line up. So when I got the chance to try it out, I had to accept.

    Now let's see if this thing is going to be an angel or a devil!

    • Designed for Fast-Paced Aerobatics and Easy Assembly
    • Beautiful MonoKote? Color Scheme
    • Glow or Electric
    • Pre-Hinged Ailerons
    • Innovative Interplane Struts Speeds Field Setup
    • Painted Pilot Figure Preinstalled

    • Pull Strings on Top Wing In Wrong Hole

    Skill Level:

    Time Required to Build:

    Frustration Level:

    What do these ratings mean?

      Name:Great Planes Christen Eagle GP/EP ARF 42.5
    Price: $279.99
    Top Wingspan: 42.5" (1080mm)
    Bottom Wingspan: 40" (1015mm)
    Wing Area: 441in² (28.4dm²)
    Weight: 5.75-6.25lb (2610-2830g)
    Length: 39.5" (1005mm)
    Engine: .46 - .55 2-Stroke, .70 - .72 4-Stroke
    Engine Used: OS 55AX
    Radio Used: Futaba 10CAG
    Servos Used: (6) Futaba S9001 Servos.
    Channels Used: 4 total - Elevator, Aileron, Throttle, Rudder

    Items Needed To Complete

    • 4-channel radio
    • 2 or 3 Standard and 2 or 4 Mini Servos
    • .46 - .55 2-Stroke, .70 - .72 4-Stroke Glow Engine or 42-60-480 Outrunner Brushless Motor (If using the recommended brushless motor, a 60A brushless ESC and motor mount are required)
    • 30-min Epoxy
    • Thin and Medium CA Glue
    • Small Drill bits
    • 6-32 Tap and Handle
    • Various Standard Shop Tools

    Recommended Control Throws

    The packaging was outstanding. All of the major components were individually bagged and taped in place with no signs of movement during shipping.

    All parts were present and accounted for and some of the notable features were the heavy-duty fiberglass landing gear, the innovative strut design, and the pre-painted fiberglass cowl.


    The manual is up to Great Planes typical standards - which are to say, excellent. Each step is documented well and clearly illustrated.

    Download the manual (1mb PDF)


    Note: The ailerons can be set up using four servos (two in each wing) or two servos in the bottom wing with slave pushrods from the bottom ailerons to the top. The manual gives clear instructions for both versions. For this review, I will be using the four servo method.

    The first thing you need to do is to align your servos on the hatches and mark the placement of the mounting blocks. The blocks are then epoxied to the hatches and further secured with screws from the outside. A 12" extension is then added to each servo wire.

    One problem I encountered was that the pull string for the servo wires in the top wing came through a hole that was too small to fit a servo plug through (this hole also needs to be clear for the strut attachment). Fortunately there is a larger hole at the rear through which I dropped a weight on a string.

    The hatches are secured with sheet metal screws (don't forget to harden the holes afterward with thin CA) and the horns and pushrods are installed. If you are using a four aileron setup, you can now repeat the process for the bottom wing.

    Two dowels are glued into the front of the bottom wing which is then bolted to the fuselage so the belly pan can be aligned and glued in place.

    I got a little ahead of myself and removed the wing's entire center covering instead of just two strips, so I fuel-proofed the exposed wood on both the wing and the inside of the belly pan.


    There is a balsa support block at the rear of the stab slot which must be removed before the stab can be inserted. The stab and fin are now aligned and glued in place with 30-minute epoxy. I inserted a small balsa shim under the stab to get the horizontal alignment correct which was broken off after the epoxy had fully cured.

    Since I had some epoxy left over (and still had some working time before it set) I epoxied the elevator joiner and tail wheel wire into their respective control surfaces. Once the epoxy had cured, I installed the elevators and rudder with the supplied CA hinges (after deepening each hinge slot a little).

    Next, the pushrods and control horns were added. Two standard servos were installed in the body and the pushrods were connected to them with an L-Bend and nylon FasLink.


    The landing gear is made from heavy-duty fiberglass. I have used this type of gear on several Great Planes models and I really like them. Flats are ground into the axles for the wheel collars and the wheels are added.

    The pants are attached with two small screws and the gear legs are bolted to the fuse. Now, using Canopy Glue, the fairings are glued only to the struts and with the addition of the tail wheel, the plane is sitting on her feet.


    There are two sets of holes marked on the firewall for either a glow or electric setup. I marked the holes I would need before drilling lest I get carried away and drill one that I shouldn't.

    Once the tank is assembled, it slides in place perfectly. I added some DuBro fuel tubing to denote which line was which.

    The engine mount can now be bolted to the firewall and spaced for the engine you have chosen.

    OS 55AX Closer Look
    O.S. 55AX

    More muscle for .40 sized airplanes.

    Increase displacement in your 40-size model the easy way: just drop in a 55AX engine! You'll enjoy more horsepower for swinging bigger props ? which means improved 3D, precision and sport flying. Best of all, there's no modifications required!

    • Mounts directly into the bolt pattern for a 46AX.

    • A diagonally-placed needle eliminates the need for a remote needle valve.

    • The 5-sided, angular head design looks great and significantly increases surface area for better cooling.


    • Stock Number: OSMG0556
    • Displacement: 0.545 cu in (9 cc)
    • Bore: 0.91 in (23 mm)
    • Stroke: 0.85 in (21.5 mm)
    • Practical rpm: 2,000-17,000
    • Output: 1.75 hp @ 16,000 rpm
    • Weight: 14.3 oz (404 g)
    • Includes: #8 glow plug, 40J carburetor, Power Box E-3070 muffler
    • Recommended Props: 12x7, 12x8, 13x6, 13x7
    O.S. 2-Year Warranty icon

    Download the manual in PDF format - Click here

    I am using an OS 55AX which should be PLENTY of power for this little airframe, and while I'm not usually a big fan of gadgets, the Great Planes Dead Center Tool is an ideal way to locate where your mounting holes should be drilled.

    Once the holes were drilled and tapped, the engine is bolted to the mount with 6-32 screws. The muffler fits into a recess under the firewall and I added a slightly modified DuBro exhaust deflector to reduce the slime factor.

    Now you need to drill the hole for the throttle pushrod tube. Since you have to drill through the firewall plus a former further back, you will need a long 3/16 drill for this - and I had loaned mine out. If you do not have one, you might be able to do what I did: Take a length of 3/16" music wire and grind one end down like a screwdriver. Then grind that end to a point with a slight angle on each side. This is called a Spade Drill and will easily go through wood.

    I actually had to drill three holes in the former before I got the angle right. Then a little creative bending will help to keep the pushrod from binding.


    Instructions for the cowl are good and easy to complete. I needed to remove the vents from the bottom for muffler clearance and of course, add a hole in the top for the needle valve extension.


    Next we add the cabane to the top wing and the end struts. Do yourself a favor and test fit the struts before you put the wings on as I had one that was a little tight. Now the wings can be mounted.

    There is ample room for the radio gear and the switch and charge jack, which I thought might be difficult to get to, went in much easier that I thought they would.

    The canopy has a partial cutout should you decide to decorate the interior which I just glued shut. Finally, I bolted the canopy in place and she's ready!

    The first day out was ideal, mid-70's low humidity and only a slight breeze which was coming straight down the runway. I fired up the 55AX, set her down, and after one last check of the controls, I taxied her out to the runway. Like most planes, the torque pulled her to the left but due to the short tail, she was slow to respond to rudder input, so the first takeoff was aborted - As was the second and third. It took me a while to get the feel for how much rudder to add and when. Even once I had the hang of it, she was still a little squirrely on takeoff. I made a point of not letting her lift off too soon, but once she had sufficient speed, a little back pressure on the stick and she rose off the ground nicely.

    Once airborne, she flew very well. I had -40% expo dialed in to the transmitter, which I'm sure helped to keep the controls soft around center. Minor trim was needed and once she was tracking straight and level, I proceeded to wring her out.

    The Christen Eagle will handle almost any maneuver you care to throw at her (short of 3D of course). Loops tracked well and rolls were crisp... and she's quick!

    Ok, so far so good, but the real test of a plane like this is its slow-speed handling, so on the down-wind leg, I reduced the throttle before turning to base and final, and did a slow pass over the runway - She passed with flying colors. On later flights, I even allowed her to get very slow on the final turn and there was no sign of her wanting to snap (which short-tailed planes can be notorious for). It was a little bouncy on landing, but that is mostly due to the fact that I always kept a little speed going.

    Check out the video to see her in action!

    Great Planes Christen Eagle GP/EP 42.5" ARF
    Or, Download the Video (24meg)

    In the intro I questioned whether this 42" Christen Eagle would be an angel or a devil. It turns out it's an angel... With a small set of horns. It's a fun, fast aerobat that I would only recommend for more advanced fliers, as a beginner or intermediate flier would find it to be a real handful.

    That said, if you're comfortable flying a hot airplane, this is a real firecracker that will satisfy your need for speed as well as perform both tame and wild aerobatics! The distinguishing color scheme looks great on the ground and make this bird very easy to see in the air! All in all, I found it a thrilling aircraft.

    Great Planes
    Model Distributors

    2904 Research Road
    Champaign, IL 61826

    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

    Everything For The R/C Hobbyist
    Phone: 1-800-848-9411
    Website: www.dubro.com

    Comments on RCU Review: Great Planes Christen Eagle GP/EP ARF 42.5

    Posted by: Mr67Stang on 10/26/2011
    Are comments disabled?
    Posted by: Mr67Stang on 10/26/2011
    Rediculous, mention the compitition and your post will not go through.
    Posted by: Mr67Stang on 10/26/2011
    Rediculous, mention the competition and your post will not go through.
    Posted by: Nitro777 on 10/27/2011
    On you approach in the video was it an optical illusion or were you wing tips fluttering?
    Posted by: MinnFlyer on 10/27/2011
    Mr67Stang, I don't know what you're talking about, but I do know that sometimes comments don't work. Try using Firefox instead of IE
    Posted by: MinnFlyer on 10/27/2011
    nhulsey, that is an optical illusion
    Posted by: wade.bower1 on 10/30/2011
    MinnFlyer, excelent job on the plane. I was trying to say something about another similar but larger plane by another manufacturer and how it was only $50 more and that post would not go through. I tried three times. Any other post as you can see posted.
    Posted by: Mr67Stang on 10/30/2011
    Just realized my freind was logged in... those comments posted by "wade.bower1" are mine.
    Posted by: Mr67Stang on 10/30/2011
    TEST TEST TEST... Hangar 9 Horizon Hobby Christian Eagle $50 less It could have been coincedence that night
    Posted by: KaP2011 on 04/20/2013
    A year and a half later the problem with the string in the wrong hole has not been corrected, the only change is now the hole Minnflyer used is no longer oval but is now round and too small for the servo plug. Arrrggggghhhhhh.
    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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