|Wing Area: 343sq. Inches|
|Weight: 27.5 - 31 oz||oz.|
|Wing Loading: 11.5 - 13 oz/sq ft||oz/sq. ft.|
|Servos: Futaba S3154 Digital High Torque|
|Transmitter: Futaba 14MZ|
|Receiver: Futaba R617FS|
|Battery: Great Planes ElectriFly Power 2100mah|
|Motor: Rimfire 35-30-1250 outrunner|
|ESC: Silver Series 35 amp Brushless|
|Available From:||Your Local Hobbyshop|
The full scale Sukhoi Su-31 is a single engine aerobatic aircraft that is very popular in air shows. Great Planes introduces their new addition to their E-Performance series, the Sukhoi SU-31 3D EP ARF! It includes light weight carbon fiber and fiberglass parts with a lightweight airframe expertly covered in Monokote.
The Sukhoi SU-31 Kit includes:
The Assembly went very quickly since most of the difficult parts were already done at the Factory. The aileron hinges were already glued in place, but I did add a couple of drops of thin CA.
Great Planes provides many different servo arms to fit most micro servos, and these need to be used if the included hardware is used.
I removed the covering from the aileron servo hole, making sure it was the correct one (there is a lightening hole near it). The manual says to either glue in the servos or use screws. The Futaba servos I used did not have any included screws with them, so I searched my parts box and found some. I mounted the aileron servos in place and glued in the control horn with 5 minute Epoxy. I would not recommend gluing in the servos; It would be difficult to change out a servo or stripped gear if needed in the future.
The included hardware uses carbon fiber pushrods and plastic ends that fit into the opening on the control horn and on the Servo arm. The plastic ends have small screws to tighten on the carbon pushrod. After getting them adjusted properly I also added a small drop of thin CA to make sure they didn't slip.
The SU-31 ARF comes with a small triangle piece of ply that is supposed to be used as a tail skid. A small metal washer is glued in it after slicing it in the middle with a knife. I used this method in my Great Planes P-40, and it did not last on a paved runway: The washer came out, and the skid wore down in just a few flights. On the SU-31 I used the Dubro Micro tailwheel and set it up just like on the larger planes. This provided excellent ground handling.
|Current Capacity:||30 amps/35amps burst|
Electrifly Silver Series 45 amp Brushless ESC
|Input Voltage:||6-12 cells NiCd/NiMH 2-4 cells LiPo (20V input w/o BEC)|
|Output Current:||35A continuous maximum 40A surge maximum|
|Max output power:||350 watts|
|Dimensions:||Length: 2" (52mm) Width: 1.02" (26mm) Height: .31" (8mm)|
The Power system used on the SU-31 is the Great Planes Silver series 35 amp ESC, Rimfire 35-30-1250 Outrunner and a Electrifly 3 cell 2100mah Lipo pack.
The Cowl on the SU-31 is held on by magnets, and it holds it very well. The instructions describe very well how to install the ring and magnets. I used a long piece of music wire in which I placed a 1" L bend on the end to reach in and apply a little Epoxy. I then removed the Cowl so I could add more Epoxy.
The Canopy was mounted using clear tape per the manual. I applied the included decals. These were already precut, so all that was needed was to remove them from the sheet and apply them to the plane.
With the battery all the way forward the CG was exactly where the manual said it should be: 2 5/8" back from the leading edge of the wing at the wing root. The control throws were set up per the manual, but I did add a little bit more throw to the high rates, a personal preference of mine.
I strapped the battery in place with Velcro straps and slid the bottom hatch in place. The magnets, and the fact that it slides back, held it through the high G maneuvers with no problem. I used the recommended 10x7 APC Electric prop on the motor, and I checked it with my wattmeter to show 30 amps at full throttle.
The SU-31 will fly all the basic sport flying stuff with ease. Aileron rolls were a blur on high rates. Loops and inverted flight were a piece of cake. The Sukhoi will fly pretty fast with the recommended Rimfire motor, but it will also slow down with no bad tip stalling. It can handle some wind, but as with any small parkflyer, not too much.
Takeoff with the modified tailwheel was simple. I just added throttle and a little rudder correction and it was airborne in 20 feet or so. With the tailskid there was no ground handling, so it had to be pointed in the direction I wanted to take off in before I hit the throttle.
Landing the SU-31 requires nothing more than lining it up with the runway and lowering the power I did not lower the power it all the way though; I left some on to "fly" the plane in for a smooth landing.
The painted Aluminum landing gear can take some abuse. It just bends back after a rough landing. The scale wheel pants also look great and didnít get damaged at all.
The Sukhoi SU-31 will fly great as a sport plane, but it will also 3D with the best of them. It feels really light on the wings, and even with the CG a little nose heavy it can still accomplish a lot of aerobatics.
I first tried some hovering. I could get it to hold a hover somewhat, but it felt nose heavy, and it would fall out as seen in the video. I flew it this way for 6 or 7 flights, and then decided to try a slightly different setup to fix this. I like larger props for more thrust on my 3D planes, so I mounted a 11x5.5 APC electric prop. When I checked the current draw, it showed 35 amps which is right at the ESC's limit. I do not recommend this setup unless you are flying only 3D since long periods of full throttle flying will probably be a little too much. After 3D type flying, I could put my finger on the motor, ESC and battery, and they were warm to the touch after a 6 minute or so flight. I moved the battery back about a 1/4" so the CG was more tail heavy than the manual called for.
These adjustments made the SU-31 hover with ease. It liked to torque roll pretty quickly though so a lot of aileron correction was needed to keep it straight or it would torque right around. I do recommend starting with the CG where the manual says for maiden flights.
I could fly from one end of the field to the other in knife edge, I didn't notice any coupling to the gear or the canopy; it just locks in place. It also does knife edge to knife edge snaps really well.
I then took it up high for a violent Blender, which can be the test of an airframe. I have had wings break, wing tubes bend, canopies fly off and batteries fly out on other planes, but the SU-31 handled it fine and would flatten out very nicely at the bottom of it.
The only thing I could not get the SU-31 to do quite right is a harrier. It had lots of wing rock, and after fighting it for a little bit, it fell out. I tried adding some spolieron mixing to it so the ailerons would go up at the same time the elevator went up, and that helped with the wing rock, but did not remove it completely.
I took the SU-31 up high and tried some rolling circles, and they were very easy. The yellow and white covering job made it easy to tell top from bottom since there are stripes on the bottom and a design on the top. Point rolls were nice and crisp with the Futaba digital servos: They centered nicely and are very fast.
If you also fly with a Futaba 14MZ radio, you can download my settings:
No, this plane is not for a beginner. It is designed for sport or 3D type flying, and it is recommended that you are past the training stage for this one.
The Great Planes Sukhoi SU-31 is a very nice parkflyer. It can be flown from mild to wild and everything in between. It assembled very easily, and the innovative hatch and cowl mounting is a nice feature. The Monokote covering really looks great and was applied well. With the 2 piece wing and carbon wing tube it can fit in even the smallest car for transportation, but I like to leave mine together to get in the air even faster!
|May 17, 2009, 08:37 PM|
nice review! thanks!
im trying to decide between this plane, and the electrifly 41" yak 54. i love em both, they both 3d, and look pretty, and they are both about the same size/cost. so idk. i guess it boils down to what the hobbystore has in stock.
|May 17, 2009, 09:22 PM|
|May 18, 2009, 11:46 PM|
United States, WI, Oshkosh
Joined Oct 2007
The Yak 54 also does not have a removable wing. The wing spars are permanently glued together - making transport more difficult. I have a Yak 54 and the horizontal stab (even with carbon fiber rod glued to the leading edge) is prone to flutter at high speed. I'm guessing the SU-31 is like the Edge 540 with harder/stiffer wood in the stab.
|May 19, 2009, 09:13 AM|
|May 21, 2009, 09:12 AM|
well GP has done it again! it seems each e-performance series plane they put out is better then the last and this sukhoi seems to be no exception. come on towerhobbies, put it on sale!
|May 27, 2009, 12:55 AM|
The Yak is crap.
-The motor mount twisted and ejected on maden takeoff, after a 5' parashoot to the ground the landing gear snapped the flimsy wood they wer mounted to and took the wing support with it.
-After replacing the motor mount and landing gear mount with a piece of fiber glass board (used for making circuit boards.) and shoreing up the wing with epoxy and carbonfiber tubing, it was up up and away.
-the clear bottom made the bottom look like the top making it very un fun to fly. Every flight was a nerve racking experience. During the 7th flight I got totaly disoriented and the plane looked like it was upright when it was inverted. SPLAT!! totaly unrecoverable.
-After every flight there was allways something needing repair. very flimsy model.
My experience with the SU-31.
-Great flying machine and the airframe is very sturdy. I can't say that about the motor mount. I'm not sure if reviewers get a plane made with sturder plywood or not, but the plywood on all 3 of my GP planes is very brittle. Once I started getting into snaps and blenders I found out how brittle this stuff is.
-First the motor ejects leaving a large hole in the wood the motor was attached to. I replace the motor mount with circuit board material. After 3 wild flights the framing on the motor mount starts to twist and fracture. Thats where I am with the SU-31 right now. I'm having the same issues with my Ultimate.
-It's doubtfull I am going to be able to sure up the mount framing, the wood is just soft and and flaking apart when I touch it. the whole assembly is twisted. I'm going to try replaceing the whole structure with an aluminum kit used for converting a 40" fuel planes to electric and re-enforcing the firewall with lightweight fiberglass, as it's made of the same brittle board the rest of the motor mount is made of.
The SU-31 is an excelent plane so long as you baby it. It will not take high stress flying without significant radical modifications. So far none of the GP planes I've flown holds up to high stress flying. I'ts a pitty because GP has the best looking planes of all the manufactures which is why I want to do my all to rescue it.
|May 27, 2009, 06:23 AM|
are you using a "hotter" then what's recomended motor? also these are 3d plans. they are built to be light, not durable.
i coated the motor mount & firewall on my edge 540 with epoxy, which strengthened it considerably.
|May 27, 2009, 10:28 AM|
Type: Brushless Outrunner
Input Voltage: 11.1V
Shaft Diameter: 4mm
Current Capacity: 30 amps/35amps burst
Max Power(watts): 390W
Recommended Prop: 10x7
Electrifly Silver Series 45 amp Brushless ESC
Input Voltage: 6-12 cells NiCd/NiMH 2-4 cells LiPo (20V input w/o BEC)
Output Current: 35A continuous maximum 40A surge maximum
Max output power: 350 watts
Dimensions: Length: 2" (52mm) Width: 1.02" (26mm) Height: .31" (8mm)
A well designed,well crafted, using good materials plane can be light and durrable. 3dhobbyshop 40" planes are prime examples. This plane is well designed and crafted but the material it's made from is worthless. Snaps,blenders and hammerheads are some of the more spectacular 3d manuvers but this plane cannot take them. It is capable of doing such manuvers but it will fall apart in very short order.
|May 27, 2009, 11:28 AM|
must just be the yak then. everybody i know and have talked to that owns one (the 41" eperformance series planes) loves it and has no complaints.
well, i have one complaint. no frigging tail wheel, which is retarded imho. ground handling sucks big time.
|Jun 04, 2009, 03:19 PM|
|Jun 04, 2009, 04:24 PM|
I did thin CA all joints I could reach. What I should have done was cover the whole assembly in epoxy and fiberglassed the motor mount or replaced the motor mount with 1/8" plywood glazed front and back.
I allready made repairs by using a dremmal to clean away the brittle excise for plywood and made a replacement mount out of 1/8" plywood,epoxy it front and back, installed the blind nuts, put vasaleen around the blind nut area, then epoxyed the mount to the assembly.
Plane flys fantastic and will do all the torqy stuff without fear of breaking the wood. Can't say that about the cowel. The magnets are not enough to keep it in place so I screwed it down. I'm thinking of replacing the cowl as the front of it is pretty much exposed and frayed fiberglass.
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