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Thread: SU-34 Review!

  1. #1

    SU-34 Review!

    Review by Kevin Petrilla:

    Hobby Lobby SU-34 FULLBACK



    Specs:
    · Wingspan: 35-1/2"
    · Fuselage Length: 57"
    · Flying Weight: 57 oz.


    Kit contents as packed


    Top View


    Bottom View


    Wing panels, top and bottom view.
    Servos, hinges, and control linkage
    factory installed


    Vertical fins, Horizontal stabs
    (hinges factory installed), and
    rear radar pod


    Thrust vectoring assembly
    Shown as provided


    Wheels with spring mechanism


    Canopy, armament, canards,
    pilots, and cockpit decals


    Nosecone


    Battery hatch. Servo lead end
    point shown…as provided


    Cheater holes in the dusts for
    extra thrust. Center esc cover shown


    Battery, epoxy, screwdriver,
    horizontal stab pushrods,
    extra parts


    Rear view of motor/fan assembly mounted


    Ducted fan, front view mounted in the duct

    Contents:
    A. Pre-painted foam fuselage with the following components factory installed.
    1 2 x 64mm ducted fans with factory installed 3500kv outrunner motors.
    2 2 x 45 amp brushless speed controllers.
    3 Retractable landing gear with semi-scale style struts.
    4 2 x Thrust vectoring nozzles (individually controlled. Up-down only, no side to side action).
    5 10 servos (9gram).

    B. 4 cell 3000mah LiPo battery pack.
    C. Wing panels (servos, control horns, pushrods, and aileron hinges factory installed).
    D. Horizontal stabs (elevators factory hinged, control horns installed).
    E. Vertical fins, Canards, Radar tail
    F. Canopy (factory cut and painted).
    G. Pilot busts and cockpit decals.
    H. Hard plastic nose cone.
    I. Weapons accessory kit.
    J. 4 cell 3000mah LiPo battery pack.
    K. Elevator pushrods, screwdriver, epoxy, and a few extra repair parts.

    NOTE: The Su-34 Fullback was provided by Hobby Lobby for this review.

    First impressions:
    The SU-34 comes well packed in a box that included foam reinforcement to help insure its safe arrival. The airframe is a bit larger than I remembered (I saw Jason Cole from Hobby-Lobby flying this aircraft at E-Jets International). The foam that the airframe is made from is of a small bead that has very small, if any gaps between the beads. As a result the airframe has a fairly smooth finish. Speaking of finish, the finish on the model is rather impressive. The surfaces are painted with precision and most of the decals are factory applied (The airframe decals are waterslide. The cockpit decals, which are stick-on, need to be applied).

    This airframe is very complete! The retracts, hinges, fans and motors, esc's, servos, thrust vectoring nozzles, and control horns come factory installed. Hobby Lobby states that assembly takes 1 to 2 hours and after seeing it in "kit" form I can believe it...minus the radio programming. The function of the retracts are pretty amazing as well. Each retract is operated by its own servo. When the retract goes up it tucks the wheels away into a pocket. When the gear comes down a spring helps to pull the wheels perpendicular to the strut...very slick!...Although the gear retraction direction is not “scale”. Overall I was rather impressed with the Fullback. You don’t often find foam airframes with this amount of detail, engineering, and level of prefabrication.


    Manual:Instruction manual

    Before I begin assembly of any model I like to read through the instruction manual a few times. As you might imagine, this is a very short read. The manual does not have much in terms of written instructions, but it doesn’t need it. The manual includes many images that clearly outline the assembly process. The manual also includes a few sections on battery/safety precautions as well as a nice section on "programming your radio".

    Assembly: Adding rudders


    Rudder removed from vertical fin


    Rudders sanded to a bevel and attached to the vertical fins with CA hinges


    Rudder control horn and pushrod added


    Hole cut in top of fuselage for rudder
    servo installation


    Rudder servo installed. I used thin
    Foam Safe CA to hold it in place

    Although the manual recommends starting with the installation of the wings, I decided to make a slight alteration with my kit first. The SU-34 does not come with rudders and I felt that an airframe this maneuverable deserves to have rudders installed. The modification to install rudders is very simple. There is an outline included on each of the vertical fins that shows where the rudders are on the airframe. I simply cut the rudder away from the fin with an Exacto knife on the scribed lines. (Note: I made the cut straight across the bottom of the rudder instead of following the offset hinge line). After I had the rudders removed from the fins I marked a line straight down the middle of the front of each of the rudders. I also marked a line on both sides of the front of the rudder about 5mm away from their leading edges. Next, I used a t-bar sander to sand a beveled edge between the front center line mark and each of the marks on the rudder sides. Now that I had nice beveled leading edges, I cut 3 slots in each rudder and inserted CA hinges in them. I used corresponding hinge slots in the fins and glued the rudders on with thin odorless CA. After the CA was dry I added control horns to the inside surface of the fin/rudder assembly.

    At this point I needed to figure out how I was going to install the servos that control the rudders. Since the elevator servos are factory installed, I knew there would already be a servo wire channel that made it to the radio compartment. I decided to put the servos on the top of the fuse as close to the elevator servos as I could without hitting them. I outlined the servos on the top of the fuse by the fin mounting bases with a pencil and cut out mounting holes. I put extensions on the servos and then "fished" them through the fuselage up to the battery compartment with a metal pushrod. ***In order to get the extensions through the fuse I needed to put a slight bend in the pushrod (toward fuse center) I was using to fish them through. I had to use a lot of patience and a little force to get them through but they eventually showed up in the radio compartment. At this point in the build I decided to go back to the beginning of the instruction manual and mount the fins later, when recommended.

    Wing installation:


    The wing panel will attach to the side
    of the fuse with a “tab and socket alignment”


    Wing panel


    Wing panel attached with the included epoxy

    With the rudders out of the way, the rest of the build went fairly quick. The wing panels are simply epoxied to the sides of the fuselage after the aileron servo extensions are connected and pushed into the fuselage. The extensions are factory installed in the fuselage.(Note: The kit comes with epoxy which actually works very well but be prepared to work quickly because it sets up very fast!) There are tabs on the fuse and wing that help you align the wing but it’s up to the builder to make sure they are level.

    Stabilizer installation:


    Stab mounting location


    Stab attached

    The horizontal stabilizers are epoxied to the sides of the rear of the fuselage. There is a tab on each stabilizer to make sure it is aligned properly but once again pay attention to make sure they are level.

    Vertical fin installation / Elevator (and rudder) linkage:


    Elevator pushrod system


    Vertical fins/rudders and linkage installed

    The vertical fins are epoxied onto fin bases on the fuselage. There are two tabs on each fin that matches slots in the base for alignment.

    As noted, much of the assembly is done at the factory. Since the elevator servos are mounted in the fuselage and the horizontal stabs are installed by the modeler, the elevator pushrods must be installed (aileron pushrods are factory installed). It couldn’t be simpler. The pushrods are already properly sized. The z-bend ends of the pushrods go to the servos and the clevis ends go to the control horns on the elevators. Make sure the servos are centered with your radio before pushrod installation.

    I used pushrods with a z-bend on the control horn end and ez-connectors on the servo control horn for ruder control.

    Radar pod installation:


    Radar pod mounting location


    Radar pod attached

    I simply glued the radar pod onto the back of the fuselage with thick Foam Safe CA.

    Front canard installation:


    Canards


    Canard mounting location


    Canards mounted

    At this point I ran out of the included epoxy. Since the parts that were left to assembly were rather small and wouldn’t be seeing much flight load, I decided to attach them with thick odorless CA. The canards are simply glued to the side of the front of the fuselage in their respective slots.

    Nose cone installation:


    Nose cone


    Nose cone mounting location


    Nose cone attached

    I used thick Foam Safe CA to glue the hard plastic nose cone on.

    Canopy installation:


    Canopy as provided. Nice paint detail


    Cockpit decals and pilots mounted


    Canopy installed

    Although the attachment of the canopy is not specifically outlined in the manual, it is easily installed none the less. Before installing the canopy, I added the cockpit decals and pilots. I installed the canopy with thick odorless CA.

    Missle Installation:


    Wing tip missles


    Missle attached

    I installed the wing tip missiles with thick Foam Safe CA. I decided to leave the other missles off for now.

    Programming your radio:


    Elevator mix to left thrust vectoring nozzle.
    Note: mix is shown as off because the mix
    switch is in the off position at this point


    Channel “6: flap” is the left t.v. nozzle.
    SW is assigned to C in the center position.
    This means that the c switch (3position)
    will activate this mix when it is in the
    center position


    Elevator mix to right thrust vectoring nozzle.
    Note: mix is shown as off because the mix
    switch is in the off position at this point


    Channel “7: aux1” is the right t.v. nozzle.
    SW is assigned to C in the center position.
    This means that the c switch (3position)
    will activate this mix when it is in the
    center position


    Aileron mix to the left t.v. nozzle


    Aileron mix to the left t.v. nozzle.
    The 3 position switch will activate
    this mix in the down position


    Aileron mix to the right t.v. nozzle


    Aileron mix to the right t.v. nozzle.
    The 3 position switch will activate
    this mix in the down position


    This is the rudder to steering mix


    Rudder to steering mix. Although this
    mix is assigned to the c switch by default,
    the position is null which means the switch
    has no effect on this mix…it is always active


    This is the screen that assigns the individual
    nozzles and steering servo to a trim knob.
    Left nozzle assigned to A, Right nozzle
    assigned to C, Steering servo assigned to B


    Trim knobs and activation switch

    The manual has a section on programming your radio mixes for the different flight modes that are suggested. The radio used in the manual is the Spektrum DX7. The pictures and text are easy to follow. For this review I used a Futaba 9CAPS with 2.4 module. My intent was to use a 7 channel receiver as suggested and y-connect my nose steering servo to my already y-connected rudders. Unfortunately, the steering servo and rudders didn’t move in the proper direction together so I ended up with an 8 channel receiver and another mix. In the end this proved to be beneficial because I can control the trim on the nose gear steering separately from the rudders. I also have individual trims programmed for each thrust vectoring nozzle. The pictures above provide all the mixes required for the aircraft as well as the steering rudder mix and the "activation" switch.
    Note: Before plugging in your retracts for the first time, make sure the end points in your radio are set low so you don’t accidentally strip the retract servos.

    Completion / C.G. :

    With the airframe completed I needed to find a good mounting place for the receiver in the fuselage. I made a balsa shelf that sits behind the battery tray and mounted my receiver to that with Velcro. The reason I made an elevated receiver tray was to separate the receiver and the battery wires better.

    With the stock battery installed, I needed 1/4 ounce of lead in the tail to balance at the recommended C.G. of 96mm (96mm back from where the front of the wing attaches to the fuse). I have 4s 3700 packs that I will be using as well. With the 3700 packs installed I needed 1/2 an ounce of lead in the tail. Since I have 4 4s 3700 packs, I decided to balance the airframe based on the slightly heavier packs. I counter sunk the weight into the radar cone and glued it in with thick CA.


    Countersunk weight for balance

    Unfortunately, the manual does not have any recommended control throws so I used the "that looks about right method" and came up with the following throws.

    Aileron = 9mm up and down low rate, no exponential. 18mm up and down high rate, 25%exponential.
    Elevator = 13mm up and down low rate, no exponential. 22mm up and down high rate, 25% exponential.
    The thrust vectoring nozzles follow the assigned rate for the given mix.

    Since I was just about ready for flight I wanted to give the Su-34 a quick run up to see what kind of power it has. After about 15 seconds into a power run I was seeing 1000 watts at 67 amps. That’s a bit more than I was expecting. Should make for some interesting flights.

    Note: There is a short video on the SU-34 page on Hobby Lobby's website on how to arm the esc's properly.
    URL here.... http://www.hobby-lobby.com/su_34_fullba ... 0_prd1.htm




    Flight:


    Maiden flight:
    Once at the field, I plugged in the battery and heard those familiar esc tones. If you don’t immediately set the controllers with your radio as noted in the Hobby Lobby video, they will chirp at you for a minute or so…they will eventually set themselves. I did a transmitter range check and once again checked to make sure my control surfaces were moving in the proper direction and that my mixes were correct. I taxied the Su-34 out onto the runway and let it come to a complete stop. I then slowly advanced the throttle. The SU-34 began to move at about 20% throttle but didn’t really come to life on the tarmac until I passed about 65% throttle. At full throttle the Su-34 gets up to flying speed pretty quickly.
    The SU-34 jumped into the air rather quickly after traveling down the runway about 100 feet and then did a much unanticipated porpoise back down toward the runway. It made one slight bounce and was back up in the air. Once in the air the Su-34 climbed out well with no signs of being marginally powered. I needed about 7 clicks of up trim and 3 clicks of right trim to get the SU-34 to fly level (Note: after re-examining the elevator position after the flight, I started with it in a slightly downward position).
    The maiden flight took place on a day when the winds were gusting around 15 mph. It was obvious as soon as I made it in the air that the wind would affect this airframe a little more than some of my other jets this size. The Su-34 has a very light wing loading and it also has a lot of side surface area. Having said that, I always felt in control of the airframe and never felt that there was too much wind.
    Some of my first impressions in the air were how well the airframe responded to control inputs and how it sounded at full throttle. Even though the airframe was being buffeted slightly, it always responded positively to inputs and returned to center well. The twin fans sound real good at full throttle and are very close to being in sync. At anything under about 90% throttle the fans are slightly out of sync.
    At this point I did a slow pass followed by a high speed pass. The slow speed passes are just that, very slow. It really is amazing how slow this airframe will fly and I hadn’t even activated the thrust nozzles yet. The fast passes are pretty quick (maybe 75mph…I will check back with radar passes), and although they are slower than what I am used to with my other airframes, the passes are faster than any other rtf minus receiver foam arf’s that I have seen.
    I had been in the air about a minute at this point and was already feeling very comfortable with this airframe so I decided to try some basic maneuvers. Aileron rolls with the SU-34 are just slightly off axis but look amazing in the air. There is a lot of stuff rolling on that x –axis! The SU-34 will loop easily from level flight, although if you try to make the loops too large it will drop at the top(The SU-34 has a good thrust to weight ratio but it is not 1:1). Next, I tried inverted flight. The SU-34 flies inverted amazingly well, maybe even better than right side up. It is easily controlled while inverted and requires minimal down elevator input.
    Since I had made the rudder modification I wanted to see how effective the rudders were. I came down the runway put the SU-34 on its side and applied full rudder to perform a knife edge. The SU-34 immediately flipped back out of the knife edge. The rudders were a little more effective than I had planned. With a little less rudder input the SU-34 will perform a knife edge but it needs a lot of aileron throw to keep it on edge. Next, I applied full rudder when flying level. Full rudder will actually flip the airframe over: Very effective! With that knowledge, I pulled straight vertical and tried a few stall turns. The SU-34 performs them with ease if you don’t try to overdue it with rudder input. The SU-34 performs all of the basic 4 channel jet maneuvers with ease (with rudder modification for 4 channels)…rolls, loops, Cuban eights, immelman turns, stall turns, split s’s, inverted flight, etc…

    Special Flight Characteristics:
    The SU-34 is a very fun airframe to fly conventionally, but there is another level…thrust vectoring. It was time to see what this airframe could do. With the thrust vectoring enabled on low rates, it was obvious that the vectored nozzles had an effect, the loops were somewhat tighter, but it wasn’t until I flipped over to high rates that the airframe came alive.

    (Elevator only thrust vectoring mix active. Note: the SU-34 has up – down vectoring only, no side to side.)

    With the control surfaces and nozzles set on high rates the SU-34 does some very impressive maneuvers. For one, the loops are incredibly tight. The SU-34 will pull out of a tight loop about ¾ of the way through the maneuver and level off almost immediately. If you stay into the throttle, you will be rewarded with a high alpha hover at the end of the loop. The SU-34 also does some amazing square loops. I noticed some flex in the wings when performing this maneuver at high speeds but haven’t had any issues yet. It doesn’t quite do the famous “cobra” maneuver too well because the wing loading is so light. If you pull up immediate it will begin to climb immediately, it doesn’t necessarily stall forward in high alpha flight to perform the cobra. Speaking of high alpha flight, the SU-34 will perform some amazingly slow high alpha passes. This is also a place where I noticed exactly how nice it was to have rudder control. Without rudder during high alpha flight the airframe will fall off to the side if you get to slow. With rudder input I can keep the airframe from falling off to the side and snapping. It will actually stall forward gently when you control the stall with the rudders.

    As stated before, inverted flight with this airframe is a breeze, but with the t.v. nozzles activated it’s a monster. The SU-34 is actually more aerobatic when performing t.v. maneuvers inverted. The loops are tighter and the airframe will actually flip when a loop is sustained with full power and full down elevator.

    (Aileron only thrust vectoring mix active)
    With the elevator mix off and aileron to thrust vectoring nozzles active, the SU-34 behaves almost as if there is no mix at all. You can just barely feel the difference when the mix is on versus off. With the aileron to t.v mix on, the rolls seem a little more axial but that’s about it. After trying a few maneuvers with this mix on, I turned it off and went back to the elevator mix…it’s much more fun!

    Landing:
    I had a few things left that I wanted to try, but the battery was beginning to sag badly (at about the 3.5 minute mark). I knew I needed to land soon. I dropped the retracts and brought the SU-34 around for a landing. The SU-34 settles into the landing pattern amazingly well. It is only a matter of holding the nose off the ground and letting the jet settle onto the runway. Unlike many other jets I fly the SU-34 sticks to the ground well with little to no tendency to bounce.

    Additional Flight Notes !!
    During a subsequent flight I happened into a pretty amazing maneuver simply by chance…although it is now easily repeated. While performing a little snap roll at the top of a vertical climb out, I managed to get the SU-34 into a perfect flat spin. Remember, the SU-34 does not have side thrust vectoring capabilities. The rudders are very effective! I had flipped the SU-34 onto its back with full down elevator and full rudder deflection. Unfortunately, the SU-34 will not do this maneuver without the rudder modification, which is why I highly recommend it. The flat spins are impressive!

    Conclusion:
    Overall, I am very pleased with how well the Su-34 flies. It tracks well and shows no bad habits when flown at speed. If you get it too slow during high alpha flight it will fall off to the side without rudder correction (rudder mod needed to correct this). This airframe is very aerobatic! I was hoping it would be a little bit faster (It is faster than I thought it would be but aren’t we all looking for a little bit more?), but I am not going to hold that against the airframe itself. Mine came with the 64mm fan systems installed. There is also a 70mm fan system upgrade available as noted in the manual. The retracts are very impressive and well thought out. They definitely add to the scale look even if they don’t retract in the proper direction. Up to this point, the retractable gear have performed flawlessly although I have had to tweak on some of the set screws to tighten things back up.
    The Su-34 Fullback looks superb in the air. It would fit well into any pilot’s hangar that is looking to take there jet flying skills to the next level. This airframe will reward you with very aerobatic yet smooth and gentle flight characteristics. It is one of those airframes that I look forward to taking to the airfield every time I go.


    Pluses:

    · Quick build – high level of prefabrication.
    · Everything included minus receiver.
    · Good fit and finish – small beaded foam.
    · Paint application is good.
    · Flight characteristics
    · Great speed for beginner/intermediate pilot
    · The retracts are very ingenious and have held up well.
    · Looks superb for an all inclusive foamy.

    Neutral:
    · Instruction manual – It is not very detailed when it comes to assembly, but doesn’t need to be. Control throws not included.


    Minuses:

    · Even though the foam looks great it is still a foam airframe and thus dents and dings rather easily.
    · Included battery is only 3000mah. thus flights average only just over 3.5 minutes.
    · The battery hatch and tray system can be clumsy to operate. The swivel latches often get caught and are hard to get over the hatch tabs. Also the size of the battery tray makes it hard to move up to battery packs with more capacity.

  2. #2

    Re: SU-34 Review!

    Videos from the review are located here viewtopic.php?f=7&t=419

  3. #3

    Re: SU-34 Review!

    I've recently ordered one of these, and I'm pretty excited. Would you recommend the rudder mod for sure?

    Vic
    Cheers,
    Vic

  4. #4

    Re: SU-34 Review!

    The rudder mod is fun to do. It can help slightly to do certain things, but the thrust vectoring works as rudders too, so it's not really needed.

    Jason

  5. #5

    Re: SU-34 Review!

    Excellent review Jason. The radio setup was a lifesaver. Thanks a million and keep up the good reviews.
    Steve

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