My first electric heli was a Thunder Tiger Mini Titan, which I bought used from a friend whilst in the UK. After returning to the US, I discovered Hobby King, and began a journey with HK 450 Pro's, and with the advent of the CX3x1000, I converted them to FBL.

I had been planning to sell the old MT on, and had converted it back to it's original ACE RC format, with a simple TX and integrated CCPM mixer/gyro unit. Happily, the potential buyer pulled out due to lack of funds, and I decided to have a go at converting the MT to FBL using one of my CX's.

In FB form, the MT was always very stable, and being sort of stretched out longways, I was expecting it to be a bit less agile than my 450 Pro's - so I was really surprised at how rapidly it would flip and roll in FBL form - faster than my 450 Pros! I initially flew it with DS410's on cyclic, and an HK15158A on the tail, but I've now replaced the DS410's with Henge MD933's, having returned the DS410's to one of my 450 Pro's.

Here are a few snaps, with some thoughts.



In the view of the left side, below, you can see the CX-ZYX mounted on the boom block using a single layer of 3M tape. The relatively bulky FrSky V8FR RX is an easy fit within the main frame, fitted to velcro on the bottom plate. This RX is too big to fit between the frames of my 450 Pro's....





In the picture below, you can see that the relatively tall Henge MD933's need to be spaced off the servo mounts. For the elevator servo, I used offcuts of some...Continue Reading

Here are a few pics of my HK 450 Pro belt, converted to FBL using the CX 3x1000 controller and a Tarot FBL head.





In the shot below, you can see the Nano Tech 4s 1800 pack fitted with 4mm bullet connectors. The Hobbywing Platinum Pro 40A ESC is velcro'd to the frame, and I run the RX lead thru the frames to the left side. Gotek 9257 tail servo is getting warm (up to 130f) at 6v and 333Hz but otherwise working OK. CX controller fixed with two layers of 3M foam double-sided adhesive tape.

...Continue Reading

So far, I've used three different motors in my HK450 Pro's.

I started with the Typhoon 2218H.



Note that the Typhoon motors use a centrifugal fan, which is designed to draw air thru the motor from the top, exhausting it thru the fan at the bottom. Installed in a 450 Pro, therefore, the fan needs to be reversed compared with the orientation shown in the image, which is how all my Typhoons came. To reverse the fan, you simply remove the bottom retaining plate, and the fan itself is a loose slice of extruded aluminium alloy.

If the fan is left in the default direction, there will be much less airflow thru the motor. The default direction would suit helis like the Mini Titan, where the motor is mounted above the maingear.

I used the 2218H for quite a while in my 450 with a Turnigy Superbrain data logging ESC and various 3s 2200 25c packs.

When set up incorrectly, (too much pitch!) the motor pulled peaks of up to 55A, but with a proper setup, running a 13t pinion, current draw was in the low to mid 30A range.

On my first 2218H, the top bearing started to spin in the housing, and after that the shaft also started to spin in the bearing. This caused enough slop for the magnets to start rubbing on the stator.

After maybe 150 flights or so and several crashes, the last crash resulted in the shaft breaking at the circlip groove. The Typhoons use a 3mm shaft and bearings, and the shaft diameter steps up to 3.17mm at the circlip. I believe that makes the shafts very prone to breakage, with a large stress concentration at the circlip groove.

Shafts don't seem to be available, but if you used a 3mm pinion, you could make a simple shaft from a 3mm drill rod using a spacer or shims under the pinion to retain the can, and therefore not weakening the shaft with a circlip groove.

Overall, it's not a bad motor. You should check the tightness of the grub screw at the bottom of the can - they were loose on both my 2218H's.

After the second crash in a month with my HK 450 Pro FBL, I had to get a new set of cyclic servos.

I had been running 2 x Henge 933's with a Corona 929MG on elevator. One of my Henge 933's had crapped out, starting to jitter a lot around neutral, and I was fed up with flying with a permanent bobble. Kauaiguy put me onto the fact that the controller can compensate for any differences in cyclic servos, so though the 929 is a faster servo than the 933, the heli flew fine, until the next crash.

Being in the UK, I had to buy servos from a brick and mortar store, and ended up getting Align DS410's, at GBP18 each, including the pesky 20% VAT (sales tax)

I could have gone for the metal gear versions, which were a bit more expensive, but since I was using Align DS4 servo arms, which are pretty beefy, I decided to go with the plastic gear version. I'm hoping the gears will strip in a crash, protecting the servo cases.

The servos are a perfect fit in the 450 Pro, and the cases look reasonably durable, though the mounting lugs are hollowed out on the underside, same as the Henge's and Coronas.

In flight, the DS410's perform very well. On the servo tester, they show 0.09s @ 6v, right in line with their specs, and they have very little gear backlash. The heli feels noticeably more "locked in" than it did with the Henge/Corona mix.

In the past, I used a Hitec 5084MG servo on the tail of my HK 450, with various gyros, ranging from an HK401b, CSM420e, Assan GA 250 and a Leader Hobby GY 520. It seemed to work well, though not really much better than the various 9257 clones I've also used.



Recently, I got the chance to fit the 5084 in my 450 FBL heli, which uses the CX 3x1000 FBL controller. I have used a Fitec FS9357D in that heli, which gave good results until I managed to burn it out. I had neglected to do any maintenance on the tail pitch control, and there was some serious binding which did for the servo in the end.

Since then, I've been using an HK15158A 9257 clone, which has the great virtue of being dirt cheap, but sufferes from a bit of slop in the gears.

Teamed up with the 3x1000, the 5084 seems to work really well. I'm running it at 6v and 333Hz, and it's staying nice and cool. (I check the linkage for binding regularly now!)

With the 5084 being a mini servo, I have to use an adaptor to fit it to the 450 Pro tail servo mount.

I first used Henge MD933 MG servos in my HK 450 Pro. They worked well for many flights, and were a perfect fit into the 450 Pro - though with the inexplicable different servo fixing bolt spacing on the Pro for the elevator servo, I had to file out the top mounting lug on the elevator servo.

The plastic cases are quite brittle - and after one crash, one of the aileron servo cases broke at the mounting lugs. I had not used any washers under the M2 bolt heads, however, and refitted the two surviving servos and a spare using washers, which I believe gives a bit more crash resistance.

The horns supplied with the servos are quite brittle, but hold a linkage ball securely enough without using an M2 nut on the back of the servo arm.

The 933's seem quiet and smooth in use, and seem to have good centring and resolution - but they also seem slower than the claimed 0.11s. My CX program box shows them as taking 0.14s @ 6v.

After well over a hundred trouble-free flights with the 933's, my next crash took two of them out. Both aileron servo arms were broken, and the servo cases cracked, and the plastic 2nd gear small pinion stripped.

I therefore decided to give the 922's a try. They're claimed to be faster than the 933's, but on the CX tester, they show almost exactly the same speed. They also run quite noisily, making a rough grating sound, and seem to have more backlash than the 933's.



Whilst my 450 Pro flew with all the default cyclic settings for the #5 preset model with the...Continue Reading

Much as I've enjoyed flying my HK 450 Pro, it has been completely transformed by going FBL, using the HK RJX style head, and the CX 3x1000 controller.

It flies almost like a sim model - and the controller makes it so easy to do piros. Maybe that's why some people consider an FBL heli to feel "robotic", and maybe it might come as a shock to my system to fly an FB heli again!

Here's the setup:

Controller CX 3x1000
Motor Turnigy Typhoon 2215H 3450kv
Pinion 11t helical onto 121t main gear
ESC Turnigy Superbrain 40A with separate Turnigy 5A SBEC set to 6v
RX FrSky V8FR used with FrSky 2.4G module in JR 9XII TX
Cyclic Servos Henge MD922 MG 12.7mm arms
Tail Servo Fitec FS9357D 8.5mm arm
FBL Head HK RJX style
Main Blades HobbyPartz 325mm Carbon (21g ea)
Battery Zippy 3s 2200 25C x 3, Zippy Rhino 3s 2200 25C x 2

I mounted the controller on the gyro mount behind the anti-rotation guide, with the servo leads facing aft. with my ESC mounted externally by velcro on the right side, and my RX on the left, all my wiring is to the rear. It's functional rather than pretty...

The Zippy Rhino packs are holding up much better than the regular Zippy's, which now get pretty warm after using up 1400mah or so, and show much more voltage sag than the Rhinos.

I got the helical gears to reduce noise, and they seem a bit quieter, but I suspect they also cause the motor to pull an extra 0.5A or so for the same HS. I'm currently using the (excellent) SB governor High...Continue Reading

I'm using this head on my HK 450 Pro (belt) heli, and quite like it. Here are some thoughts on its use.



Tiny Steel Washers

When I got the head, it wasn't immediately obvious to me to use the small steel washers in between the shouldered ball bearings that fit into the swash locker arms. The bearings are a very tight fit into the swash locker arms, and once pressed in, are almost impossible to remove. For one of the swash locker arms, therefore, I have to be careful not to over-tighten the pivot bolt, otherwise I get some binding from excessive side loading of the bearings.

The swash locker pivot bolts also serve as pinch bolts to help secure the head to the mainshaft - which seems like a good idea. The downside however is that I have to limit how tight the pivot bolt on the "good" swash locker arm is, since if I fully tighten that it will exert pressure on the other bolt, causing some binding. I'm really kicking myself for having left out the steel washers! At least blue threadlock holds the pivot bolts, and they haven't loosened in use.

Optional Mounting holes

Another good thing about the RJX head is that there are two sets of holes for the top "Jesus" bolt. Using the upper hole enables the head to sit lower, which helps agility a bit, and looks pretty good too.

Feathering Spindle - Bad!

The feathering spindle that came with my head was crap - I didn't bother using it, since it felt undersized, and the bearings were a very...Continue Reading