MicroHeli CNC Flybar Set

The following is a review of the MicroHeli CNC Flybar Set.

The first part of this review will center around the build quality of the Flybar Set.
Initially some good close up photos of the hub and arms to give you a feel for the attention to detail.
There are a lot of photos here as the whole flybar set is quite complex and intricate.

Initially I had a good feel of the flybar set, looking for slop or unwanted movement in any lateral or vertical direction. The whole unit is extremely solid and slop free in any direction you wish to stress it. The set has bearings fitted at every conceivable pivot point making for a very loose and free moving unit as a whole. The small metal rod that goes through where the flybar would normally locate was removed by undoing the grub screws. This allows the central arms to come away from the outer cradle. There are some tiny washers fitted on this metal rod that need to be inserted onto the flybar. This can be seen in the above picture on the right.
The bolts holding the cradle together need to be undone in order to get the ball links onto the center ball in the middle of the cradle arms. Upon doing this I noted that the bolts had been loctited in place, which was good to see.
Having got the ball links onto the cradle the whole thing can be reassembled with the flybar in the center instead of the metal rod shipped with the unit. The flybar should only be inserted once the flybar arms center piece is on the rotor head hub, this is because the flybar needs to go through the hub. If fitting to a standard Align flybar the bearings in the flybar carrier will be too small to fit onto the flybar. Microheli supply two plastic bushings to allow the use of the standard T-Rex flybar. I assume MicroHeli are producing a flybar so you can leave the two bearings in place, I've asked them and will update here when I have an answer. The bushings can be seen below left along with the screws and washers to secure the flybar set to the main rotor hub. Further pictures of assembly can be seen below.

Assembly of the unit is quite a fiddly operation and inserting the very tiny washers resulted in me dropping them several times and then searching around the floor to find them again. The flybar once inserted can have the paddles screwed onto the ends. In the standard kit you have a 62mm gap from flybar hub to paddle, on the MicroHeli cradle I had 59.5mm from cradle to paddle on either side.
The grub screws that hold the flybar in place are the standard T-Rex grub screws but there is no fear of stripping the thread on the MicroHeli unit as the holes are nice and deep with plenty of thread. The unit comes with two grub screws, one each side. The unit can have four fitted, one either side, top and bottom. I elected to add a couple for safety and extra grip as the grub screws are biting down onto a round flybar shaft with no flat on it.
Having got the flybar on and secured it's a simple case of connecting up all the ball links and then checking to make sure everything is aligned properly at 0 degrees pitch. My linkages required no adjustment at all, all washout and flybar arms were nice and horizontal with the pitch slider in the middle of it's slot. I later discovered I hadn't checked this properly as detailed further on in the review.
With the unit fitted and connected up I had a feel for slop. Bearing in mind my machine has the MicroHeli washout and swashplate on it (as can be seen from the pictures) there is no evidence of any slop at all in the head, either on the flybar paddles or on the main blades themselves. The whole unit is very solid and flexing the paddles or blades showed movement in control horns beneath the swashplate but no slop from swashplate upwards. The only way to eliminate this would be to install CNC control horns as the slop here is introduced from flexing in the plastic horns.

I had a feel for how free the movement was and here I discovered that I would need to do the usual trick of loosening up the ball links with some heat. The ball links are a little stiff on the flybar cradle in places but this is a well known problem with the purple links and easily resolved. This proved more of a problem than I thought, more on this later in the review

My overall impression so far is of an excellent and well thought through flybar set. Any slop I had in the head linkages is now completely non-existent plus the flybar carrier has four grub screws holding it in place, so no fear of a flybar control arm coming loose as with the standard kit. MicroHeli have also upped quality control as the screws that needed loctite were properly secured and there is no evidence of any possibility of binding throughout the whole flybar set. I can't wait to give this a try in the air. The UK weather looks like calming a bit for this evening, so hopefully I'll be able to post my first flight impressions later today.

First Flights....(eventually)

Just before heading to the field I thought I'd give it a power test and make sure all servos had full movement and so forth. I'm glad I did this, whilst I had good movement for aileron and collective the elevator was totally locked up solid.
After working over it I felt it was still a case of too tight ball links, despite my earlier efforts to free it up. The purple links are very tight on MicroHeli balls, I think they must be very very slightly larger than Align ones as even working over with the soldering iron didn't get the result I wanted. I decided to try my (original T-Rex kit) sloppy gray ball links and to my surprise they are a very nice fit, only a tiny almost undetectable bit of play but given what the T-Rex has from stock I decided I could live with that, particularly as the aileron pitch arms add more slop than the ball links ever could. I only changed a few balls to get the smooth movement I was after with almost undetectable play on the gray ball links. I was most pleased with the effort as the swashplate and mixers are moving more freely than they ever have and I haven't re-introduced the slop that I fitted the purple ball links to get rid of.

Whilst doing these checks I noticed that I didn't seem to have a great deal of positive pitch. A quick check with the gauge and things had definitely moved from fitting the flybar set. I had to shorten the blade grip ball links two turns in order to get back to my normal +/- 10 degrees. So much for my earlier check by eye, I'm glad I always give a final check with the pitch gauge before flying.

A couple of pictures of the ball link changes are below.

This problem fixed I was free to head to the field, except it was now dark :(

Well, not wanting to be put off by not being able to see I headed for the local car park which has orange street lighting, this would prove somewhat interesting but I was determined to test this new flybar out.
Wind was 5mph with the odd gust, so I would have a little work to do keeping the T-Rex in a nice hover.
In my flight plan (before it got dark) I had planned some circuits, loops and rolls and general precision flying, the point here being to test whether a more precise control was being afforded by the new flybar set. 3D was off the agenda.

In my new circumstances circuits were limited to hovering circuits and loops and rolls were definitely out of scope.
Hovering was going to be order of the day, even so, not a bad way to test the controls. I'd have liked more opportunity to fly around, I will do more flight testing and post it here, for now this would be enough to get some general impressions.

Lifting into the hover I took the normal few seconds to adjust to the T-Rex and the conditions. I then concentrated on going for as steady a hover as I could manage. Well had it been a bit calmer I could have hovered with one hand behind my back, this was impressive stuff, having got used to the T-Rex wandering around a bit I was able to get a very good steady hover until gusts blew me off center. Guiding the T-Rex around in the hover was a breeze and overall the whole thing felt more relaxed and locked in. It was at this point I noticed my tracking was absolutely spot on, having spent the last two weeks or so with the tracking going all over the place (and having installed firmer dampers with limited effect) this was more than a pleasant surprise. Clearly the removal of the slop around the flybar had brought things under some control.

I hovered around through two packs to get a good feel for things and whilst it isn't an earth shattering change in the control response, it was most definitely a lot better behaved and more predictable. Any wandering off could immediately be arrested and brought back under control and fighting the wind was proving a lot easier than in previous outings.

The next step is to give the T-Rex a proper workout with some fast circuits and precise loops/rolls, looking at the current weather forecast it appears I may have my best opportunity in a couple of days time.

Circuits and Forward Flight

In flat calm conditions I managed to get a couple of packs worth of flight time today. I limited the flying to fast circuits and immelman turns as I wanted to get a feel for precision flight rather than frantic stick twiddling. I also did some hovering maneuvers to take advantage of the conditions. This flybar set certainly has increased the precision of response on the cyclic. Up until recently I ran 30% expo on my cyclic, I have removed it all since fitting the flybar upgrade and washout set. Additionally I can hold the T-Rex (if I concentrate) over an area equal to the under cart size with good precise control throughout. Certainly the normal wandering around has gone. Transitioning to forward flight feels solid and predictable, cyclic response being positive and progressive throughout. I could have been flying a 30 sized nitro if it wasn't for the occasionally tendency of all micros to have the odd funny moment now and again. Any long term micro heli pilot will know what I am talking about here, the tendency to just drop the nose or pitch up or loose height suddenly for no apparent reason, all part of the micro helicopter flight characteristics no matter how much you tighten up the controls.

Moving on to collective response, this too is very refined and small stick movements no longer result in the heli either climbing or dropping rapidly. I need to do some normal to inverted transitions to get a feel for the tighter collective control. For now it feels smooth and no evidence of slop in the flight characteristics.

Loops / Rolls / Hot Dogging

I had the opportunity to fly two packs through the T-Rex to check out the loop/roll and general hot dogging capability of the T-Rex with the new control system. Having put the T-Rex through this I came to a couple of conclusions. One was that once you get into fast forward flight it becomes difficult to tell whether the T-Rex is flying any better or worse than in standard configuration. I would be hard pressed to say that there was noticeable difference in cyclic control response. However, my second observation was that collective control response was noticeably more refined, particularly in negative to positive pitch transitions and fast descents with transition back to hover. Normally in these situations I find the T-Rex a bit jumpy and unpredictable but I think the tightened controls around the collective have eased this.

Overall Conclusion

The flybar system certainly tightens the controls and removes a lot of unwanted slop. I have some concerns about the MicroHeli balls being a touch larger than Align ones and being stiff but some work with pliers can fix this (or fitting of loose links such as I chose to do). Hovering response is certainly much better and predictable but this is not really noticeable in forward flight. Pitch transitions, negative to positive are better and the collective response is sharper and more refined, this is purely removal of slop which is always noticeable when going from negative to positive pitch as the linkage system goes from being stressed in one direction to the other. For beginners this is actually quite a good upgrade as it brings that better hovering response and the model is less prone to wander. For experts the benefit is in the pitch transitions on the collective and the more predictable response.

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Performance

Number of ratings: 11

Rating: 3.73