Zeeflyboy's Gaui X2 build thread

[zeeflyboy]

Here's my promised build thread, there are some other great build threads on helifreak, so if you're interested in this heli it'd be worth checking them out for their own hints, tips and tricks.


I'll try and present the good and the bad here, some solutions to problems and the pitfalls to avoid! I will also make comparisons to the T-Rex 250 as it is a very popular heli that many will have experience with, and is the Gaui's closest competitor in my opinion. I have owned a T-rex 250 for a couple of years and feel qualified to compare the two, so here we go!


I ordered the simple kit with Stock Scorpion motor (nice move Gaui) and Gaui branded 22A ESC, but in a nice surprise it arrived with the servo's as well... checking out the specs and it seems they are perfectly adequate so I kept the cyclics but moved my DS95i onto the tail. It really is the most incredible servo in it’s size class and I want to do justice to this heli! On the same note I went with a YGE-30 ESC which has a brilliant governor and a built-in Switching BEC at 5.5v. The box makes some big promises "The best 3D aerobatic micro Helicopter".... so lets see if it lives up to the occasion!

Included in my Box were the contents below. All nicely packaged in the sturdy box and individually bagged.





As you may have noticed, this is much more a kit than some other offerings. The only pre-built parts are the head, tail and swash. The first thing you notice is how it’s almost all carbon fibre and metal. This heli is blinged out from the word go, witht he only plastic bits being the linkage ends, the boom support mounts (i'll talk about those later) and the swash guide.... very nice. So anyway, time to bust out the manual and get cracking!

Before starting you will want to make sure you have a good quality small philips head screw driver (00 head), and a selection of small Hex keys. Green thread lock "sleeve retainer" for attaching the pinion is recommended, as is of course some blue thread lock for the screws.

The manual is fairly clear and easy to follow, and the first thing on the list is assembling the frames.








It's nice, and surprising, to see three bearings supporting the shaft on this heli, all the more important because it runs a thin 3mm shaft compared to the more sturdy 3.5mm shaft on the T-Rex... a nice touch but the bearings could perhaps have done with being slightly bigger. Everything is a compromise however and Gaui's hunt for light weight has to mean some concessions here and there. Personally I would have taken the hit of a few grams for a slightly thicker main shaft and bigger bearings however...

Here are some close ups of the main shaft supports:






Next up we want to look at the tail, and we need to just take a little time out to look at this beauty. What a complete revelation after the nightmare that is the T-Rex 250 tail.... Beautifully machined and designed, slop is kept to an absolute minimum and the slider is glassy smooth. Before installing make sure everything is running nice and smooth and that all screws are secure and thread locked.

It is nice to see the tail belt is a similar material to the kevlar "super belt" upgrade I've been running on the T-Rex, but boy oh boy is it skinny. Keep a few of these on hand and change them out at the first sign of wear because I they look fragile. Again this is perhaps a weight saving issue but I would have much preferred a thicker belt more around the size of the T-Rex's. The X2 comes with a nice sturdy carbon push rod which is a common upgrade for T-250 owners, so it's nice to see this come in the box.

While we are talking about the tail, I may as well point out that the X2 runs a driven tail, which means even when power is cut the tail still spins with the mains. Great for autorotations, and with the bigger 250mm blades vs 205mm on the T-rex, it's actually just about possible to do a controlled autorotation. Not pretty and not a lot of room for error, but I've seen it done!










Take extra care when installing the belt to make sure you only have one quarter twist in there… with the belt being so thin it’s very easy to get it wound up in the shaft. This would not be good!

Next up install the shaft and main gear, and pop the swash and head on. The belt sits on top of the main gear on it’s own smaller gear which is bolted to the main shaft, hence the driven tail mentioned earlier. Before installing the main blades be sure to balance ethem – mine were way out and it seems from other’s feedback this is a mixed bag… some sets are close, some are way off. Do yourself a favour and make sure you balance them carefully.

The swash and head are great quality, no slop and very precise. I have heard mention of the bearings in the blade grips being overly compressed leading to notchy rotation unless you just carefully remove the anodizing on the interior of the grips to give them a bit more space, but I didn’t have those issues on my kit.






At this point I want to mention a big flaw in the design….

The supplied pinion has a long sleeve and is a loose fit to the motor shaft, requiring green thread lock to hold it in place. So far so good. The problem is that the sleeve on said pinion is too long, and will result in the belt rubbing on the motor pinion…. This would result in a very short flight, and how this one got past Gaui I do not know. There are two easy solutions to this issue that I could see, firstly you can file about 2mm or so (trial and error) off the bottom of the pinion sleeve in order to bring the top of the pinion in line with the top of the main gear, thus clearing the belt, or you can move the motor to the front mount position avoiding the belt entirely. Personally I wanted to keep the motor out in the airflow, plus the layout I had planned could do with the weight in the back, so I went with the rearward position and shortened the pinion sleeve using a small metal file.

I can’t stress how important this bit is… with the belt sitting on the pinion turning in the opposite direction you will get a belt failure sooner rather than later. This really surprised me as everything else so far had been meticulously designed, carefully laid out and finished to a high standard. Bad Gaui, BAD!

Moving on….

I then installed my electronics, set up 13 degrees of collective pitch on the micro beast and took it for some test flights…

This thing is an absolute beast. I really mean that! The combination of bigger blades, more powerful motor, slightly bigger battery and yet same AUW as a T-250 mean you have truly ballistic performance running the stock kit. Be sure to use High C rated Lipos to get the most out of it as it is a real performance machine. For the first few flips I couldn’t stop climbing because I was adding too much collective as a hangover from my much more piggish T-250.

The first problem that became apparent was one I had already read about. The plastic ends on the boom supports appear to be made of the worst plastic known to man. The strength is somewhere inbetween that of Cheese and Polystyrene…. If you don’t break them when building it, you will in flight. Mine made it 2 flights before one cracked and came loose.

Thankfully Picofly on Helifreak directed me to these puppies from CNC Helicopter http://www.cnchelicopter.com/servlet...NC-Belt/Detail for a massive $2.99 - thankfully they also have very reasonable international postage. Do yourself a favour again, and get a set of these before you even start. They are pretty much a direct fit, but are slightly thicker so perhaps consider using longer screws or filing them down to a slightly thinner height. Again, very disappointing from Gaui and not at all in keeping with the rest of the Helicopter.

Unfortunately about 10 or 12 flights in, the ball came lose from the DS95i tail horn because I’m and idiot and thought that I could use the same hole I had been using on my T-Rex 250. Evidently the hole was too big and the screw pulled out… my fault not Gaui’s. Bad Zeeflyboy, BAD.
So anyway, mid funnel at about 60 feet up my tail rod swung round, impacted a tail blade and was jettisoned off somewhere into the middle of never never land.

I then had to put an out of control spinning and in mid-funnel attitude heli onto the ground. Yeah. I’m not that good. I did managed to get it upright and softened the descent before hitting throttle hold, but let’s just say I did get to test the crash resilience of the X2.

Here was the damage:





I broke the landing gear legs, a servo arm, one tail blade where it hit the tail rod, and lost the tail rod itself. Everything else, even after some meticulous checking , was absolutely perfect. This thing actually crashes pretty well (although this was over grass). The total repair bill? $12… Not bad, although that includes some T-Rex 250 landing gear to replace the carbon ones (as they are cheap as chips and I prefer the look of the white gear with the canopy). Unfortunately muppet here ordered from abroad and the parts seem to have got lost in the customs black hole so 2 weeks later I’m still waiting. I should have ordered from a UK store as there are now several that cater to Gaui and I would have been airborne long ago. Lesson learned!

The down time however gave me a chance to tidy up my install, add my new TM1100 telemetry unit with flight pack voltage, BEC voltage, Engine temp, and soon (when it arrives) RPM all hooked up. I also modified the battery mount by drilling two new holes which accommodates the long packs more easily and the canopy now fits over with no squeezing. The shorter but fatter 1200mah Dualsky pack I have fits without modification, so pay attention to the length of the lipos you order.

Here are some pics… without landing gear, tail blades or tail pushrod. Why didn’t I order from a UK store….

One thing to note – always leave the servo cables unbraided/heatshrinked for a good length before the FBL unit to avoid transmission of vibrations, and try to make sure they are nice and loose, and not pulled tight where they may again transfer vibrations or pull the FBL unit off-axis.
















So to summarize:

- Great kit with lots of CNC metal and CF to keep even the most bling-happy pilots content. Really good looking Heli in general!
- Rocket-ship like performance with a light blade loading, it is an absolute blast to fly… Really makes the T-250 feel cumbersome and slow by comparison.
- Great overall build quality let down by a few niggles that really shouldn’t have got through QC and testing.
- Great design points like the tail really make the heli stand out from the competition in this size category.
- Slightly bigger size that the T-rex gives the heli more presence in the air while still being substantially smaller than a 450 for those small areas.

Kit used in my build:

- Stock scorpion motor
- YGE-30 ESC
- Beast X FBL controller (V3.0) with single spektrum sat
- Stock Gaui GS-093 Servos for cyclic, MKS DS95i on the tail
- TM1100 Telemetry unit
- Nano-tech 1000mah 3S 45-90C Lipos.

Hope you enjoyed the read and pics, and that it might be of use to some of you contemplating an X2!

[zeeflyboy]

Post reserved for flight photo's when she gets airborne again!

[Lompma]

Is that a 5Amp BEC?

[scar308]

Looking at this build thread out of curiosity, and I wanted one. Then go down a bit farther and see the post crash photo, I was like never mind. I still crash my MCPX alot, not ready for a big bird yet.

[desertstalker]

Originally Posted by scar308

Looking at this build thread out of curiosity, and I wanted one. Then go down a bit farther and see the post crash photo, I was like never mind. I still crash my MCPX alot, not ready for a big bird yet.

He broke the landing gear, a servo horn and a tail blade. That is as little damage as you are likely to get from anything this big.

Though the LG on this heli do seem a touch fragile...

[fusionsx00]

Yeah, this is a 600$ bird.

A bad crash would be more than a mcpx.

But its one sick heli, fly the crap out of the mcpx
And when you out grow it, buy one.