RCU Review: Great Planes Extra 300SP

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    Contributed by: Steve Herlacher | Published: May 2009 | Views: 77875 | email icon Email this Article | PDFpdf icon
    Review by

    Review by: Steve Herlacher

    Great Planes
    Distributed exclusively by:
    P.O. Box 9021
     Champaign, IL 61826-9021
    Telephone: 800-637-7660

    Extra 300 SP Video
    CLICK HERE to Watch

    Decals pre-cut
    Ease of Build
    Great Looks and Great flying

    Missing step in manual to glue anti-rotation dowel

    Skill Level:
    Low to Moderate
    Time required to build:
    5-10  Hours
    Frustration level:

    The EA-300SP is Extra?s single-seat version of the EA-300LP. The newest model of the aerobatic series, the EA-300SP is for the serious aerobatic and sport pilot. The aircraft features a lightweight oil cooling system, a sport carbon-fiber instrument panel, a lightweight avionics package and a Teflon hose kit with integrated fire sleeves. This latest model has all the design and built-in safety features of its predecessors, and has the unmatched JAA- and FAA-certification load factor to plus/minus 10G?s. It?s a thrilling ride.

    From http://www.extraaircraft.com/ea300SP.asp where you can read more details on the full scale Extra 300 SP.

    Great Planes introduces the Extra 300 SP in smaller form, which can be flown with Electric or Glow power and includes an Expertly covered airframe in Monokote covering, 2 piece wing and lightweight built up structure.

    Kit Name: Great Planes Extra 300 SP
    Price: $199.98 retail price
    Wingspan: 55"
    Wing Area: 590 sq. in.
    Flying Weight: 5.5-6.5 pounds
    Airfoil: Semi Symmetrical
    Motor:   O.S. .46AX 2 stroke
    Radio equipment:  Futaba 14MZ with R617FS 2.4ghz receiver

     Futaba S9650 Digital servos

     S3155 throttle servo

    • Square
    • Hobby Knife
    • Ruler
    • T-Pin
    • 6-minute epoxy
    • Threadlocker
    • Misc small drill bits
    • General building tools, screwdrivers, ball drivers, etc.
    • Covering Iron or Heat gun
    •  Thin and thick CA

    Hole drilled for CA to wick in
    Anti-Rotation dowels
    Digital servos used
    Pictured with the extra mounts on it
    The Extra 300 SP arrived well packed and didn't even have a wrinkle in the covering, I went over it with a Hot Iron anyway but the Monokote was all stuck down very well.

    Hinging of the ailerons was the first step in the manual. First a small hole was drilled in the hinge slot to allow the thin CA to wick in better. The Instruction say to install the wing anti rotation dowels next but they never mention to glue them. I used 5 minute Epoxy to flue mine in, don't forget to glue them!

    The servos used in the Extra were Futaba S9650 Digitals, they have a few tabs that need to be cut off to fit into the servo mounts. After gluing the Blocks of wood into the hatch with 5 minute epoxy, the servo was screwed to them, I also like to use a thin layer of double sided tape as well to make sure they won't loosen up.

    And with them removed
    Wood mounts glued  in place
    Servo mounted in tray
    The Control Horns were screwed to the Aileron, then the screw was removed and the hole was hardened with thin CA. The linkage is very simple and only took a few minutes to make and then the Wings were done.

    The next step in the manual says to align the Horizontal stab, then remove the covering. Well this step has already been completed from the factory so all I had to do was line it up with the center of the fuse which is marked with a laser burnt line on the firewall, then glue it in place with 30 minute Epoxy making sure it was level as well.

    Covering was already removed
    Laser etched centerline
    Wheel mounted
    In this picture the front is on the left
    Wheel pant mounted with screws
    The assembly of the Landing gear was done by mounting the wheels to the nicely painted Aluminum gear, then the wheel pants with the screws in from the back and finally bolting them to the Fuse. I used a little clear silicone on the wheel pant between them and the gear as well for extra insurance.

    The gear will either sweep backwards or forwards, I mounted mine with the straight side of the gear forward.


    The rudder was hinged with the included CA hinges just like the Ailerons, only the tailwheel needed to be glued in place at the same time with Epoxy. The Elevators were then also hinged with CA hinges.

    I slid the long control rods  for the Elevator in the tubes inside the fuse, then installed the Control horns on them just like the Ailerons. The Elevator servo was mounted in the wood tray and I cut one of the control rods shorter than the other as per the instructions. After the servo was centered and the Elevator halves were lined up, the 2 rods were clamped together with 2 wheel collars. I also used some silver solder and a hot iron to solder them together so they could not come loose.

    The manual states that when using a Glow Engine the Rudder servo is to be mounted in the rear section of the fuse on the bottom, it goes on to mention if a Lighter Engine is used to mount it in the tray where the Elevator servo is mounted. I guessed that the .46AX I was using fell into the lighter category so I mounted it in the servo tray next to the Elevator Servo. The opening is sized for a Micro servo but there are etched lines that when cut fit a standard servo perfectly.

    Elevator control horn location
    Laser etched to cut for a larger servo
    Elevator linkage complete
    Canopy mounting dowels
    Magnet with small strip of ply to lock it in place
    Fuel tank setup
    The canopy assembly was done next. The front dowels were glued in place with thick CA then the hatch was put on the fuse and the reinforcing circles of balsa were tacked in place in the front of the firewall with a little thick ca and accelerator so it wouldnt have time to wick in and glue the dowels to the Firewwall, then after removing the canopy thin CA was added to them.

    The canopy uses a ingenious way to hold it in place, I thought my canopy was defective as it seemed to short but it is supposed to be that way. The small magnets were glued in the holes in the canopy and in the fuse making sure to get the poles of them correct so they stick to each other. The canopy then just slides under the front cowl, then backwards and a strip of ply on the bottom of it locks it in place while the magnets hold it back. The canopy can be opened in mere seconds.

    OS .46AX Engine used
    Firewall is fuelproofed
    Great Planes center locator used to mount Engine
    Throttle servo with bent puchrod to clear Exhaust
    Bottom of Cowl needed trimmed to fit
    Cowl Mounting
    There is a wide range of Engines that can be used on the Extra, I was sent the OS .46AX 2 stroke and mounting it couldn't have been easier. The firewall was already fuelproofed along with the blind nuts for the mount installed. It was a matter of mounting the Engine on the mount so the back plate was 4 15/16" from the back of the firewall per the manual. The Micro servo for the Throttle was mounted in its slot and the linkage bent as seen in the picture so it would clear the muffler.

    After mounting the Engine I then moved on to the Cowl but I could not get it on far enough so that the engine backplate would be out far enough so the spinner would not rub on the Cowl.

    I could have added a few washers to the Engine mount but it was already done and Locktited in place. I decide to trim the bottom of the Cowl where it was hitting the Landing gear a tiny bit as seen in the picture. I recommend mounting your engine with the back plate 1/8" farther out than the manual calls for.

    Cowl mounting screw into Balsa
    Piece of lite ply added
    Cuts for the Muffler
    Receiver pack, Futaba R617FS Fasst receiver, battery and fuel filler
    The Cowl was mounted using the supplied screws but I found the top screws just threaded into thin balsa, I added a tiny piece of ply so they would have something to hold on to. The Cowl only had to be cut a tiny bit on the bottom and then a Silicone extension was installed so the Exhaust would exit the plane. The receiver battery was mounted as seen in the picture.

    I used a Futaba R617FS Fasst 2.4ghz receiver and it was mounted right next to the Elevator servo as seen in the picture.

    The last thing to do was apply the included decals. This step usually takes a while as you have to cut each one out of the large sheet and trim as close as you can to it. Not with this Extra you don't! They are already pre-cut and all that was required was to remove them from the sheet and put them on the plane!

    The Extra SP was now complete and ready to go to the Field!.


    The Balance on the Extra was checked and it fell right on the mark of 3 3/4" back from the leading edge.

    The Control throws were setup per the manual which are as follows.

  • Elevator Low rate 3/8"up and down
  • Elevator High rate 3/4" up and down
  • Aileron Low rate 3/8" up and down
  • Aileron High rate 3/4" up and down
  • Rudder low rate 2" left and right
  • Rudder high rate 2 3/4" right and left

    Since the canopy was easily removed I used the 3rd line from the fuel tank for a fill tube and left it loose in the fuse, with a plug in the end of course. To refuel the Canopy just pops off and it is sitting right there, no need for cutting holes for fuel dots or complicated fillers.

    The .46 fired right up and I ran one tank of fuel thru it on the ground to start the break in procedure. After that the Extra was ready to fly and it was set on the runway for its maiden flight. The throttle was slowly advanced on my Futaba 14MZ radio, and with a little rudder to keep it straight, it had a short take off roll and then was airborne.

    A few circuits were flown around the field and it was immediately noticed that the low rate were not much at all and I felt more comfortable flying it on high rates.

    I did land and adjust the rates to my liking which were as follows. The High rates in the manual were used for normal flying and my High rates were adjusted to get all the throw I could. Your preference will be different but the rates in the book will get you in the air and started safely.

    I also used -40% expo on all the flight surfaces.

    The Extra 300 SP will knife edge all day long and mine had no coupling, just rock solid knife edge. Inverted only required a touch of "down" Elevator to hold it level so the CG felt perfect.

    The .46 would hover the Extra but it wouldn't really pull out, if you want more power I recommend the OS .70 4 stroke. The .46 makes it a great lightweight sport flyer and it is very smooth in the air and easy to fly.

    The Extra 300 SP does great Spins and knife edge spins, along with Waterfalls if you get the timing just right.

    It handled the wind very well, as you can hear in the video it was a pretty windy day and it is hardly noticeable in the flight. The guys at the field I let fly it said it felt just like their 33% planes in the air.

    The Extra lands very easily and really slows down with no problems of tip stalling or snapping. It has a great glide to it and deadstick landings are also easy, well, as easy as a deadstick landings can get.

    See the Great Planes Extra 300 SP in action in

  • Strike a pose

    Great Planes has created a great  looking and flying Airplane with the Extra 300 SP. It can be flown as an all around Sport Plane or a 3D Aerobat depending on your flying style. With a wide range of engines, 2 stroke to 4 stroke, and Electric as well, there will be a power system for any type flyer.

    The 2 piece wing makes transporting very easy and it can fit in the smallest vehicles with ease. Although not for a beginner, the Extra 300 SP would make a great third or possibly second Airplane.

    The Extra's ease of assembly will have you from the shop to the flying field in no time!



    Great Planes
    Distributed exclusively by:
    P.O. Box 9021  Champaign, IL 61826-9021
    Telephone: 800-637-7660
    E-mail: gpinfo@gpmd.com
    Website: http://www.greatplanes.com

    OS Engines
    Distributed Exclusively in the U.S.A., Canada and Mexico by:
    Great Planes Model Distributors
    P.O. Box 9021
    Champaign, IL 61826-9021


    Comments on RCU Review: Great Planes Extra 300SP

    Posted by: ChuckW on 05/31/2009
    This is a sweet airplane. Put a YS-63 in one and it was outstanding.
    Posted by: Wingman26 on 06/16/2009
    I just did the maiden flight on mine last week, like this one I have the Max 46AX in mine, it seems to do OK on that engine, but it wouldn't hurt to have some more power. It is worth noting that the engine on mine was brand new, so its far from broken in yet. I also mounted the rudder servo next to the elevator servo and found the plane balanced perfectly with no added weight needed. I was impressed at how well this went together, everything fit and the covering was nicely done, I also really appreciated the precut vinyl decals. My initial impression of this plane is very good!
    Posted by: grbicking on 07/12/2009
    what prop did you use on the 46 ax, thanks
    Posted by: Kostas1 on 08/09/2009
    I wonder how it compares with the discontinued GreatPlanes Extra 330S ARF.
    Posted by: HugoCraft on 09/03/2009
    Would an OS 55 make it hover better??? I have an os 46 but I would assume that a 55 would hopefully take much less throttle to hover. Or would it be the close same hover feel as the .46?
    Posted by: HugoCraft on 09/03/2009
    Posted by: steven4472 on 11/18/2009
    i am building extra electric.i also used a pull-pull for the rudder.the tail of the plane is drilled for pull-pull,you just have to locate the whole.this gives me nose weight that i need for small electric motor.i used a reaper 45 with a pheonix 60.in the future i plan to do away with the heavy landing gear,wing tube will locate these in carbon fiber.im sure this one will be about 4Lbs.
    Posted by: WYATT_BURP on 12/22/2009
    hi and happy holidays , does any one have a 55ax in the extra 300sp ? if so , does it hover better than the 46 ? thank you for your time , ron
    Posted by: fltekdiver on 03/07/2010
    With the OS .46 , the plane is under powered. I flew today in 8mph winds, and the plane was flying at full throttle most of the time. I would go with an os .55AX
    Posted by: albsurfer on 03/08/2010
    Use the 55AX. Keep the prop in the 11" range. 11x7 works great for overall. I haven't tried with a 12.25x3.75 or 12x4, but I've been told by guys flying similar planes that they work great on the 55AX. Don't use the base recommended props as the engine won't hack it. The biggest I've used in the APC 12x6 and the engine struggled too much to get a worthy flight.
    Page: 1 2 >
    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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