Hirobo Freya

This is a list of tips/advice on building the Hirobo Freya. It's content comes from Jeff @ Altech, Chris B, Howard M and a cast of thousands :) . This is a work in progress and is organized by machine area.
This listing was submitted by Howard Moftich (howardm@lsil.com). If you find errors or want to feedback additions or comments, pls email.

Pictures are courtesy of Zombory Zoltán from his webpage at http://rc.zomputer.hu/pics/pictures.htm. More pictures may be found at http://rc.zomputer.hu/pics/freya/assembly/default.htm.

• Do yourself a huge favor and get 2-3 muffin tins or ice cube trays to sort and hold the nuts, bolts and washers before you start. This small hardware is not packaged stepwise. Get a caliper for this, preferrably digital or metric.
• Did you purchase the required Hirobo start shaft #404403 ($32)? This is a ROUND shaft, not hex. You cannot use a std. 6mm hex start shaft w/ the kit included coupler. See section on engine for an alternate solution. All of Hirobo's better machines (>= GPH346) use this round shaft.






GENERAL TIPS

• If you are going to Loctite something, clean it first w/ drug store iso. alcohol (91% preferred) or Acetone or MEK to get the oxidation & preservative off it.
• Consider replacing the M3x15PH w/ M3x16 SHCS and then you can use locknuts. The M3x32 PH are a problem as the stock size of SHCS is either 30 or 35. In most places, the 30 will not work so you would have to buy 35's and cut them w/ a cutoff wheel. I discovered that M3x32 SHCS's are available. They are used on JR Ergo's. JR p/n 980096. However, you may find that the 32's are still a tad short for use w/ nyloc nuts.
• I used M3 split lockwashers (McMaster-Carr) on the M3 PH bolts that dont use locknuts. They are a perfect fit in the molded-in recess for the PH screwhead.
• The manual is lazy about where to use Loctite, particularly on the head. LOCTITE IS YOUR FRIEND!
• Apply thread locking compound on every bolt that is not secured in a nylock nut.
• The machine has a tendency to do a slow wobble when hovering w/ too low a headspeed. The machine wants something like 1500+ to hover.
• The HHI universal flybar lock will not fit on the boom as supplied. If you have it, you will need to grind down the lock clamp a very little bit to open it up more. Once done, it works well. The clamp seems to be hard anodized though.
• Who was "Freya"?








HEAD

• The machine will accept up to 680mm blades (max) w/ the stock tail. The grips are 14mm/4mm. The stock blades weigh 215g once the plastic roots are glued on. I strongly urge getting some good 185g blades (I'm using SAB 3D's and they really bring the machine to life). The stock tail blades are fine but I got a good deal on SAB CF tails which weigh 1/2 as much and are wider and stiffer. Tailblade size is 95mm.
• Step 11: The spindle holders should slide smoothly into the yoke. Use thick CA to glue them into place. Run the spindle through them to make absolutely sure they're lined up before the glue sets up.
• Use silicone grease (aka O-ring grease, scuba diving store) or silicone oil (Vario) to lubricate the dampeners before installation. They should fit essentially flush in their hole.
• Step 14: There should be 216mm of flybar protruding from each side of the seesaw.
• Step 16: It is imperative and critical that the radius block w/ guide pins be securely fastened to the mainshaft. After making the phase adjustment, go back and make sure the two 2x8 screws and nuts are fastened and locked. Then, with moderate force, try to move the radius block. It is also a good idea to preflight this component.
• Step 10: Fine-tune (ie. sand down) the fit of the radius arms on the washout arms so they swing nice and smooth w/o much if any force.
• Step 12: Loctite the M5x10 button bolts.
• Step 16: Make SURE the two 4x10 cap screws are secured w/ Loctite in the upper threads of the mainshaft. Ditto on the main blade grip bolts.
• Apply a liberal amount of thread locking compound to any bolt on 0414-104 Center Hub.
• File/grind a few thou off each end of the "bird cage" steel stabilizer rods 2511-018 (the ones with a ball in the middle) to eliminate any slop in the seesaw assembly.
• Use a small amount of CA to glue the metal bushings into the plastic stabilizer rod. Too much and it will make a mess of trying to get the flybar through the hole.
• Remove one or both of the paddle weights for optimum stability and maneuverability. (Howard: I'm running the 3mm lead weight only, the 4mm brass has been removed) The paddles weigh approx 22gr w/o weight, the 3mm are about 6.5gr and the 4mm are about 10.5gr (weights approx). Update: I'm now running w/o any paddle weight and the roll rate really picked up.
• Consider adding a pair of 5/32" (4mm+) shaft collars onto the flybar before you add the paddles. It makes balancing the head easier.
• If you use the inner collective pitch arm hole and everything else to be "standard", you should get 22 degrees of pitch (+-11).










TAIL & BOOM

• Make sure the tail boom servo mount is tight before each flight.
• Do not over tighten belt and recheck belt tightness and adjust after approximately 6-10 flights.
• The Freya will tell you pretty clearly if you have the engine mixture set correctly or not. It will kick the tail and/or vibrate. It has a strong tail w/ a 5:1 ratio so be prepared for serious tail power.
• Don't like the soft plastic vertical fin? The MinAir CF 3D V. fin is a perfect fit and replacement. You will need to use slightly shorter screws though since it is thinner than the stock and long screws may interfere w/ the t/r pushrod. The MinAir horiz fin is not such a perfect fit and would require some work to fit.
• Carbon tail blades weigh about 1/2 of what the stock plastic ones do (stock ones are about 6.5grams). On my kit, the stock plastic ones were *exactly* weight matched down to 0.01g I use the ones SAB makes for XCell (kinda square-ish).
• Step 20: Hirobo has shim washers available (optional purchase) if the tailshaft has lateral play in it when installed the case. The case must be screwed together tightly to see if shims are required. In my case, 2 were used.
• Step 25: Use locknuts here. The screws are long enough.
• Step 26: Make sure to get the orientation of the ends right. Use 30min epoxy to give yourself extra time and install the screw immediately.
• DON'T forget to loctite the t/r hub to the t/r shaft!
• Step 32: The shown rudder movement direction in the manual is WRONG. The rod should be pulled forward on a Right Tx command.
• The t/r control rod can "buzz" in the rod guides when the machine is idling. You can use some very thin low-ratio teflon heatshrink (Smallparts) over the rod at those points. No big deal either way.
• When you install the short threaded rod studs into the t/r control rod, clean them and use red loctite. Then your assured of them staying put when you put the ball links on or adjust length.
• Don't bother chamfering the inner edges of the boom.
• The plastic ends of the boom supports are pretty soft and when you crank down on the M3 SHCS's, the end will mushroom. Use washers under the head.
• Use the lower boom mounting holes if the tail boom hops (vertical up and down motion). Most everyone ends up using the lower holes.








CONTROLS, ARMS AND LINKAGES

• Step 1: Elevator arm length should be 75mm and both should be exactly the same.
• Step 9: The two D short pivot bolts can be replaced w/ 2 longer E pivot bolts to get more cyclic if you desire (you would need to order the E bolts)
• You'll have to grind down one of the X lever inner plastic fillets and screw end flush to prevent rod binding from the X lever to the bellcrank.
• Consider using 2mm locknuts for the radius block (MinAir sells them).
• You dont need the 1 degree bend in the swashplate pushrods.
• Use the recommended servo horn lengths (except possibly on the throttle and tail). Yes, the elevator and aileron rods come VERY close to the canopy standoffs. You will need a long arm for the collective. Either the Dubro high strength or the special JR long arm (I dont know about Futaba).
• If you decide to use Rocket City 77E ball links, be prepared for some work since they are large and in certain places, there isn't alot of room.










UPPER FRAMES

• Consider using NYLON M3 bolts (www.smallparts.com) to secure the canopy standoffs. In the event of a crash, they would shear preventing cracking of the upper frames at the standoffs. This company is also a source for VERY small spiral wrap suitable for servo lead anti-chaffing or wire bundling and lots of other cool stuff.
• I used 0.002" brass shim material instead of Loctiting the bearings to the upper plastic frame. They shouldn't be Loctited anyway, CA (CAREFULLY) if anything.
• Add a thick washer under 0414-128 Collective Pitch Bolt or remove 1mm from each end of 0414-127 Collective Pitch Shaft to properly assemble the unit. The collective pitch bolts are threaded but not all the way. The slight unthreaded shank prevents proper tightening of the assembly. (Howard: I didn't do this on my machine and the step assembled very well)








LOWER FRAMES

• Step 6: preglue (CA) 3mm locknuts to the inside of the lower frames for the boom supports. There are 2 locations (total 4 nuts (you'll need to supply 2 )). The lower location (under the fuel tank) seems to be better (less vertical fin buzz) but requires the use of shorter M3 SHCSs so the tank doesn't get punctured. Almost everyone uses the lower holes instead of the upper holes.








ENGINE & POWER TRAIN

• You can choose either the optional Delrin 93T main gear or the 95T main gear which is standard in the kit. Some YS-STII users are using the 93T main gear 0404-706. Do not try to use a tuned pipe w/ the YS engines. They dont get along well with each other.
• You can use the MinAir 6mm start coupler ($9) if you already have a start shaft w/ integrated one-way bearing. You MUST use a start shaft w/ one-way bearing if decide to use the MinAir coupler (or some other coupler that doesn't have a one-way built in). Ron Lund has several start shafts w/ builtin one-way from an economy KSJ knockoff ($28), Vario, Paege and real KSJ units.
• Consider using a split collar instead of the supplied mast collar (MinAir/bergen) to prevent putting burrs in the mainshaft.
• Step 28: Dial indicate the fan hub.
• I think the manual makes an error as to which top washer to use on the fan hub. But the english is so poor, I'm not sure. One will fit and the other won't. As I recall, I used the Enya washer on my OS61.
• Consider using Nordlock washers (www.microfasteners.com or www.ronlund.com) around the engine and some other places like the lower frame crossmembers and the collective pitch assembly. If you use Nordlocks, increase the screw length by 2mm unless the screw is already longer than necessary for the job. Nordlock's are a godsend if you want to minimize Loctite usage.
• Carefully Loctite the clutch bell to the inner bearing and also Loctiting the start shaft to it's bearing inner race. Loctite 609 is the preferred for locking shafts to bearings. Use sparingly.
• I JB Welded those engine mount bushings to the faces of the metal mount plates. Use the screws to get good contact but make sure to remove the screws before the JB sets up and the screw holes are clean and free of excess JB. Other people use Vaseline or RTV.
• If you use the Hatori muffler (671?) that has the inlet about 3 3/8" from the front, then the flat metal piece included w/ the muffler will either be too long or too short to attach the round strap to the standoff in the molded-in hole in the lower sideframe. That is because of the weld seam on the muffler. You can either drill a new hole in the flat piece, drill a hole in the lower side frame (bad idea) or use the MinAir #4008 universal shock mount kit for mufflers. That muffler also requires a little bit of canopy Dremeling to clear it. I suppose the other Hatori ("front inlet") would not require Dremeling.
• The KSJ machined muffler clamp will fit the Hatori's and MinAir NitroPipe (which are 40mm wide). I do not know if there is a NitroPipe header that will work w/ the Freya. The engine is front facing so if you get a muffler/pipe, make sure to tell them that.






FUEL SYSTEM

• Attach a length of fuel tubing to each nipple on the tank before installing the tank in the frames because it's hard to do it once the tank is installed in the lower frames. You may just want to close off that extra hole in the fuel tank cap w/ a screw or something. I use it as a fill line.
• Use Hayes 249 black tubing as the clunk line instead of the supplied stuff. The 249 tubing (from Tower) is essentially indestructable even w/ 30%.
• CA the rubber tank mounts to the inside of the lower frames before step 6. Although, ChrisB. reports it easier to remove the tank from the frame if the mounts are glued to the tank itself (w/ RTV) and Armor-All is used to "grease" the inside of the lower frames.
• Install a length of fuel tubing over the top of the cross member that is under the tank and glue it in place or run a bead of RTV over the top of the member and let it dry.






CANOPY

• Step 41: DONT make the holes 10mm. Start w/ 6mm and see how it fits. 10mm is too large and requires you to CA the grommets into place.
• The "V" groove in the top of the canopy for the starter wand is too short and too tapered to fit a wand. Extend it another 3/8"+ w/ a Dremel sanding drum.
• You'll need an additional small half-moon cut to make room for the swashplates aileron pivot ball.
• You'll probably want to drill an approx. 1" hole in the side of the canopy to get easy access to the on/off switch. Or buy/use the alternate switch plate (Hirobo p/n ??).
• The upper canopy drill marks are very slightly too high and will probably catch the main gear on the rear edges on the canopy if you drill at that location. Not a big deal but you'll have to dry fit the canopy and Dremel down the back edge of the canopy where the main gear is to clear it.
• MinAir makes M3 screw caps (press-on fit) that work well on the canopy mounting screws so you can remove the canopy w/o the need for a 2.5mm wrench. Another huge win. Overpriced but worth it. If used, you dont need the washers. If you do use these caps, when pressing them onto the screw, use a plastic jawed vise or a piece of wood against the threads of the screw. If you use a metal jawed vise, you'll almost certainly damage the threads.
• Use new #11 blades to cut out the canopy and take your time. (Howard: maybe #11 will work on the windshield (I used Lexan scissors) but the canopy material itself, particularly in the rear, is quite thick and IMO, a cutoff wheel is your best bet.) I did not cut out the bleach bottle canopy window. I just cut the Lexan window to fit and sprayed w/ black RC car body paint from the inside. The cut marks on the Lexan windshield are very close but as usual, not exact and will require some finessing. Or mask and paint the windshield area on the canopy black and be done w/ it all and dont bother w/ the Lexan window.
• Seal the decals with a two part clear epoxy paint (HobbyPoxy 1/3 expoxy, 1/3 cataylst & 1/3 thinner) and a fine brush.
• Use "adhesion promoter" spray as the first thing on the canopy after cutting, sanding, washing, degreasing or paint will not stick very well.






LANDING GEAR

• Consider turning the landing gear around 180 degrees. The machine looks better and keeps the tail up.
• I used 30mm of skid from the back edge of the rear gear mount.
• Consider marking and drilling a small hole in one location on each skid to "pin" them into place to prevent rotation.
• Don't overtighten the set screws in the skids. It's easy to crack them (true of most helicopter landing skids w/ setscrews).






RADIO & ELECTRONICS

• The kit provides you w/ 2 small metal pieces which are servo standoffs. I dont remember if they are for the roll or collective servo but most likely, you *will* need to use them. You can delay installing that servo until the end and see. It depends on how tall your servo is. A JR4131 did require it's use.
• Install the power switch early in the assembly process before you join the upper frames. You will have to grind down a corner of the on/off switch plate a bit (JR wiring harness).
• You can use a Dubro nylon control horn and screw it into the bottom of the electronics plate (where the alternate switch location is) and mount a whip antenna to the control horn. The antenna will be supported by the lower edge of the canopy.
• If you use the supplied plastic sleeve to run the Rx wire, keep an eye on where it enters and exits the sleeve as chaffing can cut through the insulation on the wire (this is not specific to the Freya).






Thoughts on how to align cyclic servos on an X lever machine....

• I use a number of tools to do this setup. Setting up the collective, throttle and rudder are just as you'd normally do and are expected to know how to do that and are not explained.
• Tools:
  machinist's bullseye level
  6/9" torpedo level
  machinists protractor w/ long leg (General)
  homemade swashplate level (or Gary Wright level)
  calipers (dial and/or digital)
  centering gauges for calipers
  flybar lock
  
• Obviously, the most important thing is to get the machine as squared up and level as is humanly possible. Put machine on level surface and use bullseys on boom where is enters the machine. There are a couple of other places on top of the machine upper frames that also seem to be flat.
• If the surface the machine is on is level, you can use a builders square to verify the mainshaft is perpendicular to the surface. Lock the flybar so the flybar is level.
• I know alot of people just sorta eyeball it but I don't. The eyeball method yields slight non-linearities since things aren't true. You'll be battling odd machine behavior forever.
• X Lever alignment... You need to do the upper half of the linkage before you do the lower half or you'll go insane. ;)
1. Make sure both pair of rods are *exactly* the same length. Use a caliper to make sure. Connect the short rods from the backside of the X lever to the bellcrank. This makes a perfect parallelogram. Release the washout arms and links from upper half of swash and install swash level. Level the swash and then using the torpedo level, lineup/level the bellcrank screws. That sets the length of the rod that goes from the bellcrank to the swash.
   OK, half done.
2. It is critical that the swash remain level and the parallelogram is squared up and the balls are absolutely vertical. The balls on the servo and the other balls on the face of the X lever also form a parallelogram but this one is offset 60 degrees. So, zero the subtrim on the servo and install the wheel so that the balls are 60 degrees from the horizontal (use some subtrim to get it). If you've done everything right, the 2 remaining rods will be an exact fit (this is where the centering gauges come in handy). If you blew it, then one rod will be a mm or so shorter than the other. Go back and fix it.