Head, Quatro

Mfn. No: AUD1024

Availability: In Stock. Ships within 24 hours.


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We all know more horsepower is fun. With a helicopter, there are two ways of harnessing excess horsepower; longer blades or more of them. While we offer a stretch conversion, the Quatro FBL main rotor head is about more blades. Whether you want this for looks or because you're running that much horsepower, what results is incredible thrust. Imagine a finely controlled explosion! An added benefit are autorotations, which last forever with more pop at the bottom to arrest descent and briefly hover before touchdown - really cool - and all because of the added lift plus rotating mass.

Watch how it's Made in America - https://www.youtube.com/watch?v=ONpESjThqEI
See it fly - https://www.youtube.com/watch?v=GKk4OQIM39w (flown with just a tail gyro - not with an FBL-gyro)
Low head speed ops - 4S pack - https://www.youtube.com/watch?v=byQe8a1rb0k (capable of 7 minute flights in this mode)

Here's what you get with your Quatro flybarless rotor head kit. Included is the CNC machined 6061-T6 aircraft aluminum center rotor hub, four main rotor blade grips, plus hardware bags for both the head-assembly plus the transfer collar-assembly. Assembly is actually quite easy because the bearings and thrust bearings stack within the grips is exactly like the standard 2-blade P6 (as detailed in the Pantera manual) and the transfer arms assemble exactly like the seesaw or mixing arms (with bearing pairs and a hat-section secured with an M3x15 Allen Head bolt). It's easy-peasy!

A Quatro rotor head cnter, plus four of everything else . . . let the fun begin

- A Quatro rotor head cnter, plus four of everything else . . . let the fun begin!



Preparation: Use lacquer thinner, acetone, or MEK to thoroughly clean the threaded components. Along with a paper towel, this effectively removes oils used during manufacturing, which may interfere with thread locking effectiveness. This is vitally important because it helps keep everything together - as intended. Remember what we learned as kids; cleanliness is next to Godliness!

Magnetic dish PDR0047 helps keeps small parts from disappearing.

- Magnetic dish PDR0047 helps keeps small parts from disappearing



Step 1 - it's a good idea to test fit the components before assembly. For example, use an Allen driver and ensure the M4x16mm studs run cleanly into the special nut. Next, liberally coat the threads with threadlocker and assemble them into the individual spindle shafts before setting them aside to dry. The idea here is for the Grade 12.9 studs, which are harder than the spindle shafts themselves, to become permanently joined to the spindle shafts. This is important because during subsequent disassembly, e.g. to replace a bent shaft, if the stud gets stuck in the special nut and the shaft unscrews from it the rotor head becomes - for all intents and purposes - an interesting paperweight. Note; we've used blue threadlocker for this job in these photos but upon further reflection, we now recommend the permanent stuff (red) because you really don't want one of these getting left within the center nut (you've been warned).

Secure the Grade 12.9 set screws within the spindle shafts using threadlocker

- Secure the Grade 12.9 set screws within the spindle shafts using threadlocker



Step 2 - assembly of the transfer collar. Use thread locker at the M3 bolt , which secures the individual arms to the transfer collar. Also use threadlocker at the M2 bolt securing the control ball to each transfer arm, as well as on the M4x4 set screw, which affixes the transfer collar assembly to the main rotor shaft. Also use threadlocker on the pin upon which the washout links pivots (where it slips through the transfer arms themselves).


Alignment of the transfer collar is correct when the M3x15 bolt is parallel with the spindle shaft. We refer to this as 0-degrees timing. The model should fly perfectly, though you may feel free to make very slight timing adjustments, a few degrees either CW or CCW to fine tune any roll-coupling when you're flying the model without a FBL controller. That said, we have had excellent success flying with everything timed at 0 degrees and no FBL gyro whatsoever. While it's not quite as smooth as with an FBL gyro, it's definitely flyable and in the hover you'd never know there's no FBL gyro in place, which is pretty sweet.

Use threadlocker to secure the pins holding the washout links to the transfer arms

- Use threadlocker to secure the pins holding the washout links to the transfer arms



Step 3- after the threadlocker dries, assemble the spindle shafts into the rotor head. While you can use a bolt in the end, we much prefer to tighten them with PDR0058 ShaftWrench because it better ensures a positive seating against the special center nut. One thing of special notice, DO NOT use threadlocker when screwing the spindle shafts into the special center nut. Instead, what keeps the spindle shafts from loosening are the M4x6 set screws, which go in from the sides and bottom on the recess of the spindle shafts. Also, we suggest using blue threadlocker to secure the M4x6 set screws instead of red because you'll have to loosen these set screws to service the head assembly, e.g. following a crash where you'll remove and replace a bent spindle shaft.

Assemble the found splindle shafts to the special nut - no threadlocker!



In practice, managing a 4-blade rotor system is easy because you can use any two pairs of matched-blades. This is a lot easier than dealing with odd-number rotor blade heads, e.g. a 3-blade rotor systems where all the 3-blades have to match each other. How long should the main rotor blades be? Here's what we've learned; if your model is equipped with an OS 50SX Hyper engine, we suggest using 550 mm blades (like what's used for 30-class models). If your model has a higher horsepower .55-class engine, we suggest using 600 mm blade sets. And if you're flying a Pantera equipped with a NitroExpress (the 91-engine conversion), then we advise using 620 mm rotor blades.


Meanwhile, electric models really benefit from the Quatro because some motors can output as much as 4500W, which is 6 horsepower! These power systems really benefit from being loaded via a Quatro main rotor head assembly because it makes converting excess power to thrust really easy. The end results of installing a Quatro head assembly are breathtaking - and fun - because collective response rivals that of  700 class model . . . in a 600-class package.

Assembled and ready to go

- The finished rotor head


Last thing, we're often asked for blade recommendations. With a .50-.55, we use two sets of 550mm blades (we have PDR0075-550 available). If this isn't quite enough load, use one set of 550mm and a set of 600mm blades. Yes, you can mix and match to adjust the load (as long as you keep the blades pairs matched to each other, e.g. the 600mm blades one across from the other and the 550mm blades across from each other as well - for balance). We know, this sounds weird, but it works and you'll be amazed how many folks never notice - go figure! With a NitroExpress conversion, things get a little more complicated because you can install any of many big block engines like the OS MAX 61SX-WC, or the OS70, also the YS .81 and .91 as well as the OS .91 - all using the same engine mount. We've run a pair of 550mm and a pair 600mm blades with the 61 to good effect. A 70 likes two pairs of 600mm blades while the 91s like two pairs of 620mm blades. With an electric, it depends on the amount of watts involved. For example, we load a Pmax equipped Pantera with two pairs of 620mm blades and can easily pull 15 degrees of pitch, which makes for explosive climb outs! Best of all, it's great fun and you don't have to be an expert pilot to enjoy it - guaranteed to put a silly grin on your face. Last thing, are you curious how it works for a scale model? Then watch this YouTube video for a sense of how beautifully it works during smooth, scale-like flight too. P6 in an Agusta A109 fuselage: https://www.youtube.com/watch?v=bU-EvzCkWAU

Pro Tip: 
Here's a tip for static tracking of the blades before you fly. Since a 450 tail boom is 14mm in diameter (the same as the opening in the rotor blade grips), just take a short length of 450 tail boom, maybe 6-8" long and use it as a jig. Here's how; beginning at the master blade, slip the short piece of boom into the grip and swing it so the other end slips into the grip behind it. If it won't slide in nicely, just adjust the length of the link of the second grip either up or down until it does (remember, you do not adjust the length of the master grip at all, leave it alone). Next move the piece of boom to the second grip and swing it into the third grip, and adjust the third grip's linkage. Ditto the fourth, which slips back into the master grip (the one with a tiny M milled into the head). If it's perfect you're done but if not, go around one more time. Anyway, I find using this method often results in there being no requirement for blade tracking whatsoever after the first lift off.