RCU Review: Hirobo Sceadu EVO .50


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    Contributed by: Andrew Griffith | Published: August 2007 | Views: 80115 | email icon Email this Article | PDFpdf icon

    Review by: Andrew Griffith (BarracudaHockey)

    Hirobo
    Distributed in the US by:
    Model Rectifier Corporation
    80 Newfield Ave
    Edison, NJ 08837
    Phone:(732) 225-2100

    Website: www.modelrectifier.com



    Each parts bag labeled with step number.
    Fabulous machine work.
    Thrust bearings in tail hub.
    MRC includes MAH carbon main rotor and tail rotor blades in kits sold in the US.

    Narrow skid stance.
    Clutch start shaft can cause vibration problems if not aligned properly.
    I'd prefer hex head screws over Phillips/JIS.

    The Hirobo Shuttle has been around nearly as long as R/C helicopters and has undergone a series of makeovers along the way.  After the Shuttle Z series, Hirobo introduced the Shuttle Sceadu (pronounced ska doo) and recently the Shuttle Sceadu Evolution. 

    The EVO, as it’s called, is available in several versions, including a 30 size, 50 size, and even a 30 size complete with a Futaba 7C, GY401, OS37.  The included 7C radio is pre-programmed by MRC tech guru and product rep Jeff Green and is ready to go out of the box. 

    Based on the revered Freya 90, the EVO 50 is available as single servo mechanical mixing as well as the SWM version, Hirobo’s name for CCPM.  The subject of this review is the EVO 50 HPM single servo mechanical mix kit.




    Kit Name: Hirobo Sceadu Evolution 50 (EVO)
    Price: $499
    Main Rotor Span: 1345mm (52.95")
    Flying Weight as tested: 8lbs 3oz
    Blades: 600mm MAH
    Engine Used: OS 50 Hyper
    Gyro used: Futaba GY 401 w/ 9254 digital tail servo
    Governor used: CSM Revlock 10
    Radio equipment: Futaba 9252 Servos, R149DP Receiver, Duralite 1650Mah Lithium Ion battery with 5.1 volt switch safe regulator.

    • 1 Gyro and 5 Servos.
    • 50 Class Engine and Muffler.
    • 6 Channel Receiver and Battery System.
    • Metric Allen Wrenches or Drivers.
    • Blue Thread Lock.
    • 4mm and 5.5 mm Wrenches or Nut Drivers.
    • Medium CA.
    • 6mm Start shaft with 1 way bearing.



    1. Ready to unpack.
    2. Box contents.
    3. LOTS of parts!

    Since RCUniverse is free of the space limitations of conventional print media, I have decided to do a complete build guide.  The only online one that I am aware of has been taken off line, so hopefully this will become the place to go for assembling the Hirobo EVO 50.

    The kit arrived at my front door by the large brown truck driven by what my lovely stepdaughter refers to as the 'airplane man'.  I found the EVO well packaged and an inspection revealed that it had arrived safely and intact.  While I have built several Hirobo helicopters before, the EVO that I owned was purchased used and frankly didn’t need all that much work, so I had never built one before and was looking forward to reviewing the kit from the ground up

    Hirobo has neatly packaged everything in bags that are numbered to correspond with the assembly steps.  With only a very few exceptions, you open a bag, assemble all the parts in that bag and move on to the next step.  Resisting the natural male urge to start tearing into things, I started as I always do by unpacking the manual and reading it cover to cover.

    If you've built a helicopter or two, the EVO should present no problems.  If this is your first kit however, the manual might be a bit intimidating.  This is not a knock on Hirobo but seems to be the norm for most of  the current manufacturers manuals.  Most of the steps consist of mechanical drawings and are interspersed with helpful notes, but the builder is left to decide on his own assembly sequence.  Study the manual carefully, highlight the notes and follow the build sequence here and you won't have any problems.

    A note on tools before we get started:  Photo 4 shows the tools I have on hand.  If you plan on being in the hobby for a while, you will find most of these tools worthwhile purchases.  A dial or digital caliper comes in handy often, especially for making precision pushrods.  You can take that a step farther by purchasing the Vario push rod nubs; these make building pushrods an exact science. 

    You will also see me reference a bearing greaser called "The Grease"” from Pete's RC.  While not required, greasing the bearings during assembly will help them last a lot longer.  The delrin plastic crank lock tool makes fan installation fast and safe.  Hardened hex drivers won't wear and strip out bolt heads, and the inline amp meter makes setting up control throws without binding very precise.

    I also highly recommend a set of Japanese Industrial Standard (JIS) screw drivers for working on any kit from China or Japan.  They fit the screws much better than a standard Phillips screwdriver and will save you much frustration.  WIHA and Tamiya both sell screw driver sets that fit the screws included with the EVO as well.

    4. My favorite tools.
    5. Elevator A Arms.
    6. Elevator rocker assembly.

    Step 1:  The holes in the A arms where they snap on to the swash plate are unidirectional, so make sure the Hirobo logo is on the outside.  Lightly sand the ends of the elevator rocker until the A arms will fall under their own weight.  Go slow so it doesn't get sloppy.  Ray Hostettler would call this making the helicopter 'kissy kissy'. Close examination of photo 5 will show the Hirobo logo on the right hand A arm.

    Step 2:  Use the thin line for the clunk.  Keep an eye on it and replace it with a quality clunk line when needed.  I've found that the stock clunk line included with most kits does not hold up well to exhaust pressure from 30 percent helicopter fuel.  Remove the flash from the tank neck with an X-acto knife and flush the tank with a bit of alcohol.  A glow plug wrench works perfectly to assemble the fuel tank stopper with its 8mm size and deep socket well.  Give the tank a vigorous shake, and make sure the clunk doesn't stick.  Mine stuck in the front of the tank twice during testing despite being assembled according to the instructions.

    Step 3: JIS (or the WHIA or Tamiya) screw drivers work best to get torque on these frame screws without stripping them.  If you try this step with a number 2 Phillips head screw driver, you are going to be in for some frustration.  Don't bother tightening down the front screws for the battery tray as you have to drop that to install the battery or receiver. (My model ended up with the voltage regulator in there)  Don't honk down on the rear screws so it has enough room to pivot down when you take out the front two screws.

    Step 4:  I started with the rubber isolators for the fuel tank; spraying a little armor all on them makes them easier to work with.  If you are using a greaser, go ahead and grease all the bearings.  Locktite the bearings into the bearing blocks.  Separate the four 10mm self-tapping screws and set those aside with the third bearing block, separate the four 12 mm hex heads and use them for the canopy supports.  Use medium CA on the forward canopy support rubber caps to secure them to the canopy support and install them in the holes as shown in the manual, use the remaining hex screws to install the aft canopy supports in the holes shown.  Use two 10mm self tapping screws and install the bearing block to the right side frame (don't tighten these yet!).   Use three self-tapping screws and install the servo frame to the right frame. 

    7. Cleaning mold flash.
    8. Fuel tank assembly
    9. Final fuel tank assembly.
    10. Fuel tank complete
    11. Servo frame assembly.
    12. Frame build up.

    Lay the tank, elevator rocker, and the bearings in place.  Put two 32mm screws through the left frame and make sure they go through the holes in the lower tail drive bearing block and into the right side frame.  Put a nut on one of the screws and tighten it down then stop and look at all the bearings and make sure they are properly captured in the seats and ensure that the fuel lines aren't pinched in the frames.  Also make sure the 4 tank isolators are in the divots in the fuel tank.  If everything looks good, install a nut on the other bearing block screw and put a dab of locktite on the bolt (clean them all with alcohol) and tighten it, remove the other nut, locktite the threads and tighten it down. 

    I like the design of using the 32mm screws for the frames vice using self tapping Phillips head screws going into soft plastic frame spacers.  This will save the occasional frame break down to replace stripped spacers and means less total screws.  I wish they had taken this one step further by using hex head screws and nyloc nuts for the frame assembly but they can be ordered in packages of ten from your favorite retailer.  The part number for the 32mm screws is 2532-053 and the nuts are 2505-020. 

    Install the two remaining 10mm self tapping screws into the lower main shaft bearing block (again, don't tighten, leave 1 or 2 mm of play on all four of these screws) and the three 12mm self-tapping screws into the forward servo tray.  The oddball self-tapping screw goes behind the fan shroud as illustrated in photo 14 (this one took me a minute).   Photo 15 shows the screws in this step and are marked with a red dot to save you some time staring at the drawing in the manual.  Tighten everything but the lower main shaft bearing block.

    13. More frame build up.
    14. Odd man out.
    15. Correct frame holes to use in step 4.

    Steps 5 & 6:  This bag isn't labeled as step 5, but it's the one that contains the black drive belt as noted in the instructions.  This is one area where you don’t use all the parts in one bag before you move on.  Take the tail shaft and put the 2.5mm thick spacer on it and set it aside.  The counter gear set is already assembled; I put a bit of blue locktite on the shaft where it seated into the lower bearing block.  Install the assembly; make sure to get both screws started before you tighten one.

    Step 7: Nothing special going on here, mount the gear and install it per the instructions; a dab of medium ca will keep the skid caps in place for a while.  This is one area I think Hirobo missed the boat; I would really prefer wider stance skids.  While the high stance helps keep the tail rotor out of the dirt, I think wider sturdy skid struts would go a long way to helping prevent a tip over.  The Shuttle series uses the same skids.  Remember there is no need for locktite where nyloc nuts are used as in this step.

    16. Completed frame set.
    17. Landing skids.
    18. Main shaft and auto hub.

    Step 8:  This is the first area in the manual that both the 30 and 50 size versions are referenced due to the fact they use different gearing, the EVO 50 uses 8.7:1 gears, an 87 tooth main and a 10 tooth pinion gear.  Take the main gear and attach it to the auto hub with four self-tapping screws.  As with the frame screws, the auto hub holes are VERY tight and you will be well served by using a JIS screw driver to install them.   

    Lubricate the one way bearing with TriFlow or very light machine oil and put the autorotation drive shaft down through the one way.  Put the .2mm shim over the drive shaft as shown in photo 20 and place the tail drive gear over the shaft aligning the bolt hole.  Put the main shaft down through the top and middle bearing block.  The end of the main shaft that is knurled goes towards the rotor head (it keeps the radius block from rotating on the main shaft) and align the lower mast bolt (Jesus bolt) hole with the shaft.

    Put the two plastic spacers on either side of the tail drive gear where the lower mast bolt goes through and install the lower mast bolt with a nyloc nut.  There are two holes in the bottom of the main shaft, you want to use the lower hole.  I believe this main shaft also fits the original Sceadu 30.  The quick way to tell that you have the correct hole is look at the upper mast and lower mast bolts.  If they are lined up you have the right holes.  If they are 90 degrees apart on the shaft you used the wrong hole and it will throw your final linkage measurements off.

    This bolt should be snug but not over tightened.  Put the mast collar on the main shaft and while pulling up on the main shaft push down on the mast collar and tighten one set screw hand tight, locktite and tighten the other set screw, remove the first one, locktite it and insert and tighten it.
    19. Completed main gear.
    20. Don't forget the spacer.
    21. Taking shape nicely!
    22. Swashplate
    23. Washout arms.
    24. Completed washout base.

    Step 9: Build the swash plate.  Remember there are two different length ball stand offs.  The outer ring of the swash plate is plastic so I found it easier to cut the threads with a 3mm bolt as mentioned in the manual.  I also put a drop of medium ca on the short 4mm pivot bolts; use locktite on the 7mm pivot balls on the inner star of the swash plate.

    Step 10: Put together the washout assembly.    Start by pressing the bearings into the washout arms.  Put the balls on the 8mm bolts and screw the balls into the outer holes on the mixing arms.  Don’t strip the plastic; just put the screw in far enough so the ball doesn’t rotate.  Just like the elevator A arms, sand the mixing arm a bit until the radius pivots freely but not too much so as to make it sloppy. 

    It used a small drill press vice to set the pin in to the radius arm and mixing lever as it was a very tight fit and wanted to get even pressure.  You could also use a pair of channel lock pliers or other suitable tool but make sure whatever you use pushes against the pin nice and straight.  When I was done the radius arm would fall under its own weight and the pin was a very tight fit in the mixing arm.  The bearing sleeve is a work of art and eliminates the easy to lose shim/washer found in other designs.

    25. Thrust bearing assembly.
    26. Grip and spindle.
    27. Head block and grips.

    Steps 11 and 12 involve the main grip assembly.  The most important thing here is to mind the orientation of the thrust bearings, the bearing assemblies that bear the centrifugal or outward pulling force created by the spinning rotor blades. 

    First install the pivot balls on to the main rotor grips, a small drop of med ca will help here.  Grease a set of radial bearings and install them on the hub side of the grips.  Grease the other set and set them aside.  Get the spindle, a spindle bolt and the largest washer and put one spindle bolt on.  Slide a radial bearing over the spindle followed by a .5mm thrust washer (the thinnest of the washers in this package).  Next remove a thrust bearing set (I’d do this one at a time so you don’t get the bearing races mixed up) and find the race with the tight fit over the spindle, you can slide them both on the spindle, one will rock back and forth, one won’t, the one with the tight fit goes on first, then take the ball cage and using the grease from the greaser pack it with grease. If you aren’t greasing bearings, use the silicon dielectric grease that you will need for the spindle.  Then put the last bearing race on the spindle.  Ensure that the bearing race grooves are facing each other and cupping the ball cage then use the spindle to pull the whole stack into the main blade grip.  Repeat the process on the other grip and you should have both sides done.

    Lubricate the spindle with silicon grease (it should still be in one of the grips).  Insert the metal main rotor hub into the plastic head block and make sure the bolt holes are aligned.  Install the bolts that hold the plastic to the metal head block.  Slip a 1.5mm spacer over the spindle up against the inner radial bearing on the blade grip and push the spindle through the head block. Put another 1.5mm spacer over the spindle and put the remaining blade grip on the spindle.  Install the spindle bolts with locktite.

    28. Check your grip orientation.
    29. Upper mixing arms.
    30. Fly bar seesaw assembly.

    Step 13: Elevator see saw assembly.  I like to get as many small loose parts out of the way quickly, so put the two smallest bearings into the ends of the see saw.  Put the two short bearing spacers into two of the remaining bearings and push these into the see saw with the flange towards the center.  Take the remaining four bearings and push them into the washout arms so you don’t lose track of them.  Make sure the main blade grips are oriented as shown in photo 28; then mount the see saw to the main rotor hub with 8mm hex screws and washers.  If you don’t have the grips oriented correctly at this step, you have to disassemble things to get it straight. 

    Finish building the upper mixing arms by installing the balls with the 8mm screws.  Novice flyers and those progressing to a larger machine for the first time will probably want to install the mixing arms in the outer “auto stability” holes.  There is a few factors at work here but to avoid an advanced rotor head theory discussion, if you find your EVO is pitchy in forward flight with the mixing arms set on the inner holes you can move the balls to the outer holes and still retain full aerobatic capability.  Another factor is blade choice, aggressive blades respond better to using the outer holes while more stable blades allow you use the inner holes without the EVO becoming pitchy in fast forward flight.

    One of the really nice things about the EVO is that it's highly tunable in its stock configuration.  Don't be afraid to experiment with different mixing arm, blade style, and paddle weight choices to see what works best for your style of flying.

    31. EVO paddle detail.
    32. Pushrod measuring.
    33. Quick UK Pushrod Tool.
    34. Flybar control arm detail.
    35. Notice silver index marks.
    36. Mavrikk ball link tool.

    Step 14:  In addition to the parts bag for step 14/15, retrieve the flybar from the bag with the tail boom and boom supports.  Start by making up the push rods; the book gives shoulder to shoulder measurement of 14mm, I prefer ball center to ball center measurements so I can use my push rod tool for my calipers but this works just as well.  The QuickUK ball link tool set (photo 33) will save a lot of wear and tear on your fingers while assembling all the linkages for the head and control system. 

    Put a small drop of medium ca on the stabilizer bar stoppers that fit into the flybar control arms, make sure the machined in washer is facing inward (visible when they are installed as shown in photo 34 ) and push them all the way into the flybar control arms.  Make sure they are seated so the face is flush with the flybar control arm.  Now take the flybar control arm and a 15mm machine screw.  One hole the bolt will slip right through, the other hole you would have to thread the bolt into, mark the smaller hole that you will be threading the bolt into, I used a silver sharpie pen as shown in photo 39. 

    If you mark the flybar control arm on the side opposite the molded logo, the marks will end up on the bottom when you’re done J.   Push the flybar into one control arm, then through the see saw and through the other control arm.  Take one push rod and give a few twists of a ball reamer and snap it on to one of the pivot balls and make sure if you hold the sides of the ball with your fingers that the pushrod falls under its own weight.  Do the same to the other push rod and push the 15mm machine screw into the flybar control arm opposite the mark, make sure to capture the pivot ball and screw it into the other side where the mark is.  Do this on both sides, don’t strip out the plastic but make sure these bolts are snug.   When you are done here, there shouldn’t be any side to side play in the flybar control arms.

    Take one of the four set screws that hold the flybar in place and put it in one of the holes just tight enough to create some drag so the flybar doesn’t fall out but so you can still move it.  Center the flybar.  I got 126mm sticking out of either side.  Install another set screw with locktite, remove the first, locktite and tighten it in place.  Push the control arms towards each other and thread lock and tighten the set screws on the other side.  Check your measurements when you are done.  Put the inserts into the paddles and screw the paddle onto the flybar so that the flybar is completely through the hole looking down.  The book says 108 mm between the flybar carrier and the edge of the paddle, but to get it threaded in far enough that I was comfortable with I got 101.5 mm on both sides.  Don't tighten the set screws on the paddles yet, we will put paddle gauges on during final setup.
    37. Head ready to install.
    38. Proper swash alignment, note odd ball goes to right.
    39. Washout and head installation is complete.

    Step 16:  This is where all the sub assemblies we built come together.  Put the swash plate on first, lube it with a few drops of tri flow or machine oil where it slides over the shaft.  Align it as shown in the picture with the middle ball on the swash on the right side of the helicopter and snap on the elevator A arms. 

    Oil and slide the washout base on to the shaft and snap the arms on to two inner balls on the swash plate.  Slide the radius block on and then fit the head.  Install the upper mast bolt, don’t over torque this bolt, just tighten it hand tight.  I prefer a shouldered bolt here.  Measure 3mm between the bottom of the head block and the radius block; it was difficult to put a caliper in there so I just used a 3mm hex driver to set the distance.

    There’s no mention of it in the instruction book, but the addendum shows that the remaining part is a set screw that threads into the radius block like a self-tapping screw.  Also, go ahead and snap the pushrods from the flybar control arm onto the washouts.  Mind the orientation of the logo and make sure to check that the ball links all move freely.  At this point there should be very little drag in the control system. 

    40. Collective pitch arm and push pull rocker assembly.
    41. Tail case assembly.
    42. Tail hub thrust bearing and grip assembly.

    Step 17:  Time to build the collective pitch arm.  Nothing special here, just follow the exploded diagram.  I set the bearings for the elevator rocker in the arms first, then the 16mm bearings in the frames after greasing both sets.

    Step 18 and 19 are dependent on whether you have a 30 or a 50. Since we are building a 50, we use the steps on the lower half of the pages.  I skipped ahead to step 19 and installed the bearings into the arms.  The large T shaped arm for the aileron lever gets the two flanged bearings; the other bearings go in the remaining three arms.  I found it easier to use a screw to cut starter threads in all the places that balls are going to be installed; they can be somewhat of a chore to start the screw with the ball on it and you can avoid stabbing yourself with a screw driver.  The X levers are marked L and R, so be sure to put everything where it belongs. 

    (Note, in photo 40, the T lever for the collective has the single ball that goes to the collective pitch arm installed backwards, the ball goes towards the inside so it lines up with the collective pitch arm)

    Step 20: If you are inclined to replace the frame screws, seven hex head screws and nyloc nuts wouldn’t hurt here as well.  Make sure you place the .1mm (very thin!) spacer between the tail pulley and the bearing.  Don’t locktite or tighten the screws yet, just get them started into the nuts.

    Step 21: In kits sold in the United States,  MRC has thoughtfully included MAH carbon tail blades that are larger in area and stiffer than the stock blades.  If you are just starting out, put the blue plastic tail blades on; they are a lot tougher, but when you start doing intermediate aerobatics, you may benefit from the better carbon tail blades.  As you will be increasing the mechanical gain of the tail system with larger blades, you may have to reduce your gyro gain slightly to compensate. 

    Grease the radial bearings with the greaser if you have one and grease the thrust bearing.  If you don’t have a greaser, use the silicon dielectric grease that you used on the spindle to lubricate the thrust bearings.  These are assembled the same way as the main rotor head, with the larger diameter bearing race going towards the hub.  When you are done putting the blade grips together, you will feel some play in the grips, that’s fine, it’s a result of using just one radial bearing and the larger diameter of the inner thrust bearing race.

    43. Tail blade comparison.
    44. Proper tail assembly.
    45. Tail boom ready to install.

    Step 22:  Hirobo has stepped up and given the EVO two point tail rotor pitch control, an excellent design.  This assembly is complete from the factory but the linkage was a bit stiff.  As with the elevator arms and mixing levers, you can fit the pitch links to the yoke and sand the flash from the yoke if you have to so that with the pins installed the pitch links pivot freely and without play.  When working with C clips it’s a good idea to work inside a large clear freezer bag to keep them from flying away.  This tip alone could save you several minutes of crawling on the floor with a flashlight.   

    Step 23: We now mount the tail rotor and tail pitch change mechanism to the tail case.  You may find it easiest to hold the tail case so that the lever collar is horizontal and carefully sit the washers over it and slip it into the tail case and start the two bolts so that the washers stay put.  After you install the guide pins into the tail pitch mechanism, slowly spin the black tail pitch guide (the part captured by the guide pins) with your finger with a very light touch.  At some point during the rotation you will feel the guide hit the guide pins.  This is a result of the molding process and we have found this on more than one model.  Take a thin file or emery board and take a small bit of material out of the channel until you can spin the guide freely with a very light touch of your finger.

    Step 24: Thread the belt through the boom.  Check the orientation of the belt.  I stuck a small LED flashlight in the boom to make sure there was only ¼ twist in the belt.  Verify that the tail rotor is turning counter clockwise when the main rotor is turning clockwise.  The easy way to remember is that the tail rotor should kick dirt towards the front of the helicopter if it touches the ground. Locktite and tighten the tail case screws

    Step 25: I like these tail pushrod guides!  They are adjustable and easily removable should you need to change the tail boom.  Also note that if you prefer a black tail boom, Hirobo part number 403304 that’s made for the GPH346 is a direct replacement.  If you have any aspirations of upgrading to a carbon tail pushrod, take a moment to examine the three tail rod supports, the one with the vertically oriented slot goes closest to the frames, the one with the smallest hole goes in the center and the remaining support with the horizontal slot goes towards the tail case.  Install the four frame screws and nuts, but I wouldn’t locktite the screws or tension the belt until the first time you fly it.  (Don't forget to locktite the screws!)

    Step 26: Nothing special here, build the tail boom supports as shown in the book.  The book calls for epoxy on the ends, I used medium CA. The point is to keep them from vibrating.

    Step 27:  Install the boom supports and the fin set.  Beginners should stick with the stock fins, intermediate and expert flyers will probably want to either skeletonize the stock fins or install carbon fins to help up the piro and flip rate.  When doing this step, make sure you have both bolts on each support started before you tighten anything down.  Also the horizontal fin brace has a top and bottom and the bottom is angled where the boom supports attach, see the illustration in the manual.

    47. OS 50 SX-H Hyper chopper engine extraordinaire!
    48. Delrin crank lock and homemade fan tool.
    49. Installing the fan.
    46. Its starting to look like a helicopter!

    Step 28:  It's time to install the engine and clutch assembly.  The same page on the directions show the installation of both the 30 and 50 size engines so make sure you are using the ones on the left side of the page for the 50.  The engine choice was an easy one, the OS 50 Hyper engine sets the standard for 50 class helicopter engines, I have 3 of them in Raptors and had no qualms about using one in the Sceadu.  Unlike a Raptor, you need to make sure you leave the washer between the front bearing and the fan. (NOTE: I couldn’t find it in the manual but if you ever need to replace just the clutch liner the part number is 400-004. It’s a universal liner so it must be cut to fit.)

    The best way to install a fan and prop nut on a helicopter engine is to use the OS delrin crank lock tool and a fan tool as seen in photo 50.  If you choose to use an alternative method, I highly recommend against the use of a piston lock tool, the likelihood of denting the top of the piston is high and once that happens it’s only a matter of time before you blow a hole in the piston in flight.  The phenomenon has become common enough for most of us to refer to them as a piston punch tool.  

    The other two keys to installing the fan and nut so they stay put is to clean the threads with alcohol before assembly and doing the installation the night before you try to fly so the locktite has time to cure.  I’ve never found a need for red locktite on a fan assembly and I have never had one I have put together with this procedure spin a fan off while trying to start the engine.  

    Before you assemble and locktite the fan, if you are going to use a governor it’s best to do a little planning now.  I don’t bother to balance the fan again after I install the governor magnet, but I like to make sure the magnet is farthest away from the piston when the piston is at top dead center.  So fit the fan without screws, spin the fan hub onto the engine and figure out which of the four possible mounting points will give you the magnet dimple the best orientation.  I found one that put the magnet dimple exactly opposite the piston while it was at TDC, so I marked the fan and hub with a sharpie, removed it and bolted the fan to the hub.  Once you install the fan and prop nut, you can go ahead and put the back plate back on the motor, install the ball for the throttle arm and mount the clutch to the fan hub.

    While we are here I'll mention that the Sceadu fan has more vanes and an airfoil shape common in aftermarket upgrade fans.  Other kits include fans with straight vanes that I find to be less efficient.  This is one of the touches that makes the EVO stand out as a well designed helicopter.

    50. Note washer and o ring on the start shaft.
    51. Dial indicating start shaft.
    52. Ready in install in the frames.

    Another tip for governor magnet installation is to drill a small hole from the dimple through the fan.  This does two things.  First it prevents an air bubble from forming in the epoxy and lets the excess out so you can easily wipe it off.  Second, if you decide to remove the magnet at some point, it’s a simple matter of using a small punch or finishing nail to push the fan out with no damage to the fan or magnet.  As with the fan tightening, I’ve never slung a governor magnet in hundreds of flights since I learned this installation procedure.

    If you have or have access to a dial point indicator, I highly recommend dialing in the run out of the start shaft.  I’ve cured several vibration issues for people on the EVO by dial indicating this critical area.  Mount the engine to the mount without locktite.  Leave the glow plug out while you do this procedure as well.

    First check the run out of the fan hub to within 2 thousandths, then install the clutch and check the end of the start shaft right below the milled out spot for the set screw; again look for 2 thousandths or less run out.  Mine was nearly perfect, less than 1 thousandth.  Locktite the clutch bolts and recheck.  If your shaft run out is out of tolerance, loosen the clutch bolts and wiggle it around, try turning it 180 degrees.  If it’s still out, you can use aluminum foil to make very thin shims between the low side of the clutch and the fan hub.  If you find that the hub is true and the start shaft at the base is true, measure it near the end of the start shaft.  If this is out you can slip a brass tube over the start shaft and use it to “tweak” the shaft until it’s within 2 thousandths.  I’ve rarely had to do more than bump the shaft to get it right on.  This is one of the areas that if you spend the extra time now to do it right, you will be rewarded with a silky smooth running helicopter.

    Now remove the engine mount bolts one by one and locktite them and reinstall and tighten them.  Also if you are using a governor, now is the time to mount the bracket and install the sensor.  I’ve had excellent results with the CSM Revlock 10 and Revlock 20 so I went ahead and installed a Revlock RL 10 that I had on hand.  The main differences between the 10 and 20 are newer firmware and the ability to run the 20 in rev limiter mode as well as governor mode.

    Slip the clutch bell over the start shaft and put a bit of green locktite around the upper part of the pinion so that the pinion bearing doesn’t slip.  You will save time if you remove the entire carburetor.  Work the engine into the frames and ensure the start shaft pops up through the top of the frame and the top of the pinion is seated into the pinion bearing.  Install the engine mount bolts and if you are going to use one, the remote glow plug adapter at this time.  Once you are done, put the start shaft coupler on to the start shaft and install the set screw so it seats on to the flat spot and is securely locktited in place.  I’ll install the muffler during final setup so it’s not in the way.

    53. Engine mounted in frame.
    54. Starting servo install.
    55. Pushrod tools.

    Step 30: Mount the servos in the appropriate slots, mind the spine orientation and use the servo plates with no eyelets on the collective servo.  Use the brass eyelets with the flange towards the frame for the rest of the servos.  If you have servo plates lying around, I prefer them to the eyelets and screws as I think they get a good tight even pressure on the rubber grommets, just don’t honk down on the screws, the servo should be tight but you want the rubber to do some vibration isolation.  Make note of the diagram in the manual when mounting the tail rotor servo, the servo goes in the lowest set of holes.  I skipped mounting the rudder servo until step 37 so I could align and tighten everything at one time.

    Step 31:  Mount your receiver and battery.  The compartment on the bottom is designed for the battery.  I installed a Duralite 1650mah battery and 5.1 volt regulator.  The battery and receiver mounted nicely on the front of the tray, so I installed the regulator in the lower battery compartment as far back as I could to get some separation between the regulator and receiver.  With the rear mounted tail servo, the EVO tends to be a bit tail heavy so I wanted the battery as far forward as I could get it.  (This battery proved extremely light and 4oz of lead were required for good balance and smooth tracking forward flight)

    Step 32:  If you are familiar with my reviews you have seen me use a caliper and the Vario pushrod nubs to make perfect pushrods.  Hirobo gives the shoulder to shoulder measurements for most of their links not ball center to ball center; but where I can, I’m going to use the nubs.  Also don’t forget to work your links with a ball reamer if they are tight.  Tight linkages in the control system manifest themselves as a helicopter that you feel like you are always chasing to keep in a hover or always messing with the trim; that’s because the servos and control system aren’t recentering perfectly each time.  Also taking the time to get the flash sanded off the mixing arms and all the slop out of the control system will help with this.
    56. Screw center to screw center=
    57. Perfect pushrod length.
    58. The better way to perfect pushrods.

    Step 33: The push pull elevator control rods.  The rods between the Z lever and the elevator control lever are 66.5mm center to center.  Study the diagram on page 36 and get this right or there will be binding in your linkage.  Notice that the balls are slightly offset on the servo wheel.  You also want to make sure that on the elevator servo wheel there is one ball mounted towards the frame.  You need to use the ball that has the recessed area for the screw head here so it doesn’t hit the servo.  You are pretty much forced to use blank servo wheels here and drill holes.  The book says 9.5mm out from center.  The Futaba wheels have concentric circles with distance from center marked on them, so if you have these on hand, it makes life a bit simpler.  (Please note, use only the servo arms designed for the servos you are using, different servos have different spine counts and while they may look and feel like they fit they can and will slip a tooth under flight loads if you use the wrong type) 

    I’m not sure why they give approximate measurements, the only rods that should vary are those from the servo arm to the first bell crank (or Z lever in Hirobos case), the servo rods can vary due to different case dimensions in different servos. 

    Step 34: The rods between the Z lever and the aileron bell crank are 65.5mm center to center.  Same setup here with the offset balls on the servo wheel.  Also, this is where you use the other ball that has a recess for the screw head. When you are done, the rods should be the same length, and if you disconnect one rod and move the servo to full travel, you should be able to drop the link right on the ball; if it’s not, you don’t have the geometry correct.

    Step 35:  Follow the manual, there’s no offset here mounting the linkage balls so everything should line up square.   Make sure before you assume the servo is centered that you have no hover pitch set in your radio.  I inhibit that and hover throttle during initial radio setup.  Most people use a ¾ stick hover these days so they are pretty much useless anyway.  Another trick is to set your middle three points on your pitch and throttle curves to 50 percent when you setup your pitch and throttle servos (this works well for ccpm installations as well) so as long as you have the stick somewhere near center, the servo will be at its mid point.

    59. Aligning servo arm and throttle arm.
    60. Proper throttle linkage geometry.
    61. Precision paddle alignment with Mavrikk paddle gauges.

    Step 36:  It's time to setup the throttle, and contrary to popular belief, this can be fairly simple.  The first step is to setup the transmitter.  Make sure your end points are 100/100 and pull the throttle trim all the way back.  Measure from the center of the throttle arm to the center of the servo spline.  Use a straight edge and loosen the screw in the throttle arm to adjust the arm to 90 degrees when the straight edge is laid from the center of the 2 screws (see photo). 

    Go from the throttle arm to the servo (this is why I haven’t mounted the muffler yet) to the servo and turn the arm 90 degrees at a time until you find the arm that’s closest to 90 degrees; use the smallest amount of subtrim you can to get it perfect or use a wheel and drill a hole.  Make up a pushrod with the center to center dimension you got by measuring the screw to screw distance. 

    Mount a ball at 13 to 14mm out on the servo arm and snap the pushrod onto the ball.  Move the stick to full throttle (you should be using a default throttle curve of 0 to 100 with HOV-THR disabled) and move the carb to full throttle and see if the ball and pushrod line up.  Adjust the end point until they do, now go to low stick and the carb to full low (closed) and adjust the end point till they line up.  If you find your end point much over 100, move the ball out one hole and start over.  You want to make sure you have equal throttle end points. 

     If you got the measurement for your throttle pushrod right, the end points should be equal.  Now push your trim back up to neutral and that should be within a few trim clicks of a reliable idle. (In fact it was a perfect idle as I found out during flight test day)   If you are using Futaba gear, go to your throttle cut menu and set it up so that with throttle cut activated the pushrod goes to fully closed.  If you are flying PCM, give full throttle and turn off the transmitter, the throttle servo should move to fully closed in a second or two; if not, setup your fail safe to pull the throttle to idle or cut.  I prefer cut because if it hits the dirt and looses battery power you don’t want that motor coming back to life.

    Step 37: Tail rotor setup.  Step 30 has you mounting the tail rotor servo but I waited until I got here so I could make sure everything lined up.  Mount the servo using the lower set of holes and mount a ball 17mm out on the arm.  Slip the push rod into the guides and set the tail rotor pitch change slider to mid throw.  With the servo arm straight up, you should be able to tilt helicopter nose down and the rod should hit the center of the ball, tilt it nose up and the rod should slide back and hit the tail pitch change ball.  Adjust the guides until you can rock the helicopter back and forth and the rod slides smoothly and hits the center of the balls and tighten down the rod guides.  Install the push rod ends and set the slider for the middle of its throw. 

    Turn on your radio and set it so that a switch controls the gyro and the gain to 50 percent in each mode.  Make sure right rudder makes the servo pull the rudder pushrod, if that’s wrong, reverse the rudder channel.  Pick up the helicopter and turn the nose to the left, make sure that the servo again pulls the rod (it gives right rudder to correct the left turn), if that’s wrong go ahead and flip the reverse switch on the gyro.  With the gyro in rate mode adjust the limit pot on the gyro so that there’s as much throw as you can get with no binding in either direction. On the GY401, make sure that if you are using the servo that comes with it (9254 or 9253) that you have the DS switch to ON and the delay pot set to 0. 

    Turn off the receiver, set the switch to heading hold mode and turn on the receiver.  The light should flash and come on steady.  Flip the idle up switch and ensure the light stays on.  If your radio supports different trim for each flight mode and the rudder trim is different between normal, where you initialize the gyro, and idle up, then the light will begin to double flash and you will get a drift in flight when you change flight modes.  Push the throttle stick up and back and make sure the light doesn’t start flashing; if it does, you have REVO mixing enabled and need to inhibit it.

    At this point all the basic flight controls should be installed and set up.  Ensure everything is going the correct direction.  In the Raptor Titan review I illustrated the use of the Hangar 9 inline amp meter; I hooked it up between each servo and the receiver and moved each control from one extreme to the other looking for high current draw at the extremes to make sure I had no binding.  At 100/100 end points on the cyclic I got 7 degrees of cyclic on the main blades which is fine for my style of flying, and I set minus 25 percent exponential on both the aileron and elevator.

    I had skipped locktiting the set screws on the paddles during assembly.  I went ahead here and put a set of paddle gauges on to ensure that the paddles were even with the flybar carrier and square to each other.  Photo 61 shows out of alignment paddles, adjust them until the edges of the paddle gauge line up perfectly.  Good paddle alignment helps prevent pitch sensitive forward flight.  This is especially important if removing both the lead and brass weights from the paddles.  Tighten one set screw, remove the other, locktite it and reinstall it then do remove and locktite the first one, be sure to do this to both paddles.  For the test flights, I’m going to go ahead and leave both weights in.  Given my previous experience with the Sceadu though, I’m sure it won’t be long before both sets of weights are in my field box. (It took two flights!)

    You want to set up your collective pitch so that with the pitch curve at 50 the collective linkage on the servo and the first bell crank are straight up and down.  You can use the same technique as the throttle setup by setting all 3 mid points to 50 that way if the stick isn't perfectly centered it doesn't matter.  At this point the blades should be at 0 degrees pitch, the washout arms should be level, and the collective tray should be in the middle of its travel.  Make any minor adjustments to the rods as required.

    I had initially set up the EVO for -10 to +10 in idle up 1 but flight testing called for a bit more pitch and the final setting ended up being + and - 11 degrees. 

    With initial setup out of the way I put everything on charge and started on the canopy and decals.

    62. Canopy and Decals ready to apply.
    63. Kit comes with carbon main and tail blades.
    64. Completed electronics installation.

    Cutting out the canopy is easy, just score the lines lightly with an x-acto knife several times; a new blade will cut through after several passes.  I drilled the holes for the screws through the windshield and canopy before I removed the tape or cut out the windshield area in the canopy as it was stiffer that way.  Remove the windshield and finish cutting out the canopy and when that’s done, install the windshield with the self-tapping screws.

    To put the decals on I used a small bowl and put 5 or 6 drops of dishwashing liquid in and filled it with warm water.  Use dish soap and wash the canopy and your hands at the same time.  This will get any mold release and fingerprint oil or grease off the canopy as well as your hands. 

    Cut out the decals and dip your finger in the water and spread it over the canopy where the decal will go, remove the decal from its backing and dip it completely in the soapy water and place it on the canopy.  Slide it around till you get it where you want it.  If you are having trouble and the water starts to dry, dip the decal in the water again and start over.  Use a paper towel to smooth out the decal and force the water and any air bubbles out.  When you are done you can go over the canopy either with a heat gun or let it sit out in the sun for a few hours.  If you use the heat gun, keep it moving or you will burn the decals.  I wave the heat over an area and go over it with the paper towel to push it down and set the adhesive.  I also go over any sharp points with an artist brush dipped in clear nail polish.

    That’s about it for assembly and setup.  Time to break in the new Hyper engine and do some test flying.


    A final check at the field was conducted prior to fueling.  I always like to have a second set of eyes go over my helicopters before a maiden flight or after a major repair.  Robert Taylor was on hand and as a veteran of several EVO 50 builds and rebuilds, as well as being a licensed A&P mechanic, he was well qualified to give the Sceadu a final QA inspection. 

    After a few minor issues were found and corrected, Robert gave me the tip of inspecting the tail pitch slider channel and using the emery board in the channel to make sure it spins freely.  This is one area that it pays to check large egos at the flying field gate.  Don’t be ashamed to have someone look over your machine; they don’t even have to be an expert to spot something you might have missed because you have been looking at the same helicopter for hours on end during the build and setup process.

    The EVO was fueled with 30 percent Magnum helicopter fuel and the engine started for the first time.  Before going anywhere, I wanted to double check two radio settings that I had done by eye during throttle setup.  The first thing I tested was throttle hold to make sure the engine settled into a reliable idle.  Once throttle hold was set, I activated throttle cut to make sure it would kill the engine.  Both worked perfectly so I restarted it and let it sit at a high idle for a minute or so then slowly advanced the throttle.  As I suspected, the engine died right away.  The needle valve was closed to 2 turns and the engine restarted, this time the engine picked up and the helicopter lifted into a very stable hover. 

    Two clicks of right aileron trim were all that were required for hands off hover on a nearly windless but HOT (96F) Florida day.  Some right trim was expected, a bit of right cyclic is required to counteract translating tendency; the tendency of the helicopter to slide to the left in a hover from the tail rotor blowing the helicopter sideways.

    I flew 1 full tank only hovering for two minutes then landing and sitting at a high idle for one minute.  The next tank we leaned it 3 clicks and monitored the back plate temperature.  I didn’t want to burn up a brand new engine on a hot and humid day.  This flight was mainly flying circuits and getting the feel for the cyclic rate, expo rate and to get the engine leaned to the point the back plate was warm but not too hot. 

    During the third flight, we leaned it a few more clicks and engaged the governor. Everything worked as advertised, so I did some basic aerobatics.  At the top of a loop the engine quit!  No bailing out of the first autorotation.  The MAH blades auto rotated surprisingly well considering their narrow chord, and the EVO settled nicely on to the runway.  Once I started breathing again, post flight inspection revealed the clunk stuck at the front of the main tank.  The very same problem occurred on the next flight. Two flights, two autos, no broken parts; I decided to call it a day.

    Day two was planned for fully aerobatic flights; I shortened the clunk line by 4 mm and couldn’t get it to stick so I felt ok about the clunk issue.  Cyclic response was positive but sluggish with the weights installed.  If you are going to remove paddle weight start by taking out the lead weights.  They are very soft and with the centrifugal force created by the rotor system the weight migrates to the end of the lead stick and it makes removal quite a chore.  We removed both the brass and lead weights and cyclic response was greatly improved. 

    The EVO did every maneuver we could throw at it.  Funnels were solid and predictable; the helicopter tracked like it was on rails through loops and rolls.  Multiple rolls were no problem and with a head speed of 1950 no bogging was noted.  The tail response was crisp with the MAH carbon tail blades and the piro rate surprisingly fast considering the solid tail fin. 

    Flips both forward and backwards were nearly stationary and I found no need to adjust the radius block to alter the rotor head phasing.  I really don’t like the plastic radius block so I will be replacing it with a metal EX radius block.  I’ll also be ordering carbon fins and Infinivation dampeners for it as the stock dampeners appeared to be a bit soft for my liking, though they clearly contributed to the rock solid hover.

    Although we were not able to capture it on video, during subsequent test flights our local hot shot pilot made stationary piro flips and hurricanes look easy.


    See the Hirobo EVO 50 in action!
    Large File

    Hirobo EVO 50 Video (Small file)

    Strike a pose











    This is a great time for model helicopter pilots!  The good news is there are so many choices in the 50 nitro powered class that are quality helicopters and most of them perform very well.  The bad news is there are so many choices in the 50 nitro powered helicopter class that are quality helicopters and perform well.

    The EVO 50 excels in some areas and other models excel in others.  I found that the instructions were not aimed at a beginner though with a little experienced help a modeler could certainly complete one as his or her first helicopter.  It was a bit heavier than some of the models out there but that contributes to its stable hover and rock solid fast forward and backward flight characteristics.  On a breezy day the EVO is still rock solid. The EVO priced competitively and becomes a great value when you consider MRC includes carbon main and tail blades.  Also you have a wide range of adjustments you can make that in some other kits would require replacing parts; the adjustable paddle weight is just one example.

    Support in the United States for Hirobo is through Jeff Green at Model Rectifier Corporation, and Jeff is one of the most accessible product managers in the industry.  Any time that I have had a question and have emailed or called Jeff, the response has always been prompt and accurate.   Jeff is one of the true good guys in the hobby and stands behind the products he supports.

    The EVO 50 is capable of flying better than 90 percent of the model helicopter pilots out there.  A beginner will have a great platform that will teach them the basics and grow with them as they progress in their flying.  An intermediate pilot will appreciate the carbon blades and engineering excellence in the design of the kit.

    The EVO is a fun helicopter to fly and would make a great practice machine for someone with a larger helicopter that wants to save on fuel and parts.  It makes a great primary helicopter for any beginner to upper intermediate pilot due to its smooth and nimble flight characteristics.  A 50 size helicopter that fly's like the EVO breeds confidence to learn new and difficult maneuvers without fear of breaking the bank after the occasional interlude with terra firma.


    Hirobo Sceadu Evolution 50
    Distributed exclusively by:
    Model Rectifier Corp.

    80 Newfield Ave
    Edison, NJ 08837
    Phone: (732) 225-2100
    Website: www.modelrectifier.com
    email: mrcsupport@modelrectifier.com


    OS Engines and Futaba Radio Equipment
    Distributed in North America by:
    Great Planes Model Distributors
    3002 N. Apollo Drive
    Champaign, IL 61822
    Phone: (217) 398-8970
    Web Site: www.futabarc.com and www.osengines.com
    E-mail: helihotline@greatplanes.com
    product used: OS-50SXH Hyper, Futaba 9CSuper, Futaba 149DP, Futaba GY401/9254, Futaba 9252 servos.

    CSM
    Distributed in North America by
    Advantage Hobby
    PO Box 6988
    Champaign, IL 61826
    Phone: (217) 867-2300
    Web Site: www.advantagehobby.com
    E-mail: ihelp@advantagehobby.com
    product used: CSM Revlock RL10 Governor


    Comments on RCU Review: Hirobo Sceadu EVO .50

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    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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