AH-6Z Littlebird Night-Ops build project

[Zeeflyboy]

So, I said I was in something of an acquisition mode and I wasn't lying!

Here's some of the electronics I've amassed so far:

-Scorpion HKIII 4035-450 Motor... POWER!!!! Peak power of 4200 Watts to be precise... This thing is designed for 700 size helis but although this is a 600 build it is going to be a heavy bird - it certainly doesn't hurt to have the power available to get out of trouble. This will require some modifications to the frames to get it to fit as it's simply too big. The kv of 450 is spot on though - with a 12T pinion it should allow around 12-1300rpm at around 90% throttle which should be about right for the 5 blade head and semi-symmetrical blades.

- Futaba BLS451 servos for cyclic... I've used these before in my 600 Pro before I went to a high voltage arrangement. Beautifully smooth servos with plenty of power and importantly reliable!

- Futaba BLS251 servo for tail... again, great heli tail servo. Does the job on 3D monsters, so should have no issues here.

- Gryphon 7075 LMT BEC.... The beating heart of my system - this will power almost everything! Input Voltage Range : 11V ~ 75.6V (3~18 Cells), Output voltage Range : 5.2V, 6.0V, 6.8V, 7.4V, 8.4V, Output current (Peak) : 20A, (Cont) : 10A.... also note a small nimh buffer pack. In the event of BEC failure this pack will supply power for long enough to get down safely.

- Skookum SK-720... The brain! one of the best FBL units I've ever used - one also resides on my 600 Pro - and soon to get the all important GPS module which is really the enabling technology that made me even consider doing this project.





So that has managed to tick off a lot of the boxes of things left to buy. I also have the cameras on the way which should be waiting for me when I get back to geneva with any luck, already have an IMRC 5.8ghz vTX going spare to put into the project and have ordered a video switch and few other bits and bobs from flytron... so whats left to get in terms of magic boxes?

Slightly depressingly - SK-720 GPS module (when it comes out!), a second imrc 5.8ghz vtx, imrc 5800 duo, EZUHF diversity rx, SPS 120A magnetic switch, some PPM decoders, maybe some splitters, and one of these magic ppm-max type doohickeys. My 600 Pro will be donating it's YGE 90A HV ESC (another very high end ESC) and in return will be treated to an upgrade after christmas.

I've been giving some thought to redundancy on this build, since it will effectively be a flying bank account (not to mention big and scary with a lawn mower on top).

Camera/video signal wise we have two cameras already, and each can be supplied by the main BEC voltage stepped up to 12v by two separate stepups... in the event of failure of the BEC the nimh will still be supplying power so they will stay live as will all the control electronics... the IMRC vtx's can perhaps run from 1 of the 6S packs and will obviously have redundancy built right in - if one fails the second will hopefully still be transmitting and the imrc duo will simply switch to the one that's still working.

Electronically, as previously mentioned, we have the BEC backed up by a buffer pack that will take over in event of failure. During normal use the buffer pack remains topped up by the BEC so will always be charged and ready to kick in. Flight pack current usage and voltage will be monitored by the eLogger and displayed in the FLIR view, with audio alerts that will also be heard when flying with the interior cockpit cam view. As an extra precaution, the gyphon has an adjustable low voltage alarm that uses an LED - this will be routed to the cockpit dash and when the voltage starts getting low there will be a flashing LED warning displayed in view of the camera.

Signal wise we already have a diversity rx... in the event of total signal loss however the failsafes can be set in such a way that the GPS unit takes over and flys the heli either into a position hold mode, or into a return home mode where it will fly back and hover 10m above the starting point.

To cover unusual electronic failures we have the RTH function on a switch which will bring the heli back as long as it is still able to fly.

So while there are of course still hundreds of ways in which strange and unfortunate things could bring the heli down, that only really leaves ESC failure as my big concern. I'm happy to autorotate a normal pod and boom, but FPV AND scale with low headspeed/5 blade head I think this scenario is destined for doom. Perhaps the crash can be controlled though... I can always practise FPV autorotations in Phoenix RC now at least! To this end however, she is getting a very nice YGE 90 HV ESC which hopefully will not put me into this undesirable situation!

[wgt40w]

Do you work in a Bank ?? !!!

[Zeeflyboy]

no... but perhaps I should!

Single handedly kick starting the economy lol.

[Zeeflyboy]

I've been pointed in the direction of this little gem by a friend on FPVlab... I think it's currently in development.





it's called ppm max, and basically it steals two channels (7 and 8 for example) and uses them to encode... are you ready??

- 2x proportional channels for Pan/Tilt
- 2x 3-position switch
- 4x 2 position switch

That's effectively giving you a total of 14 channels from an 8ch system (it gives you 8, but you lose 2 of course).

So for this build the traditional channels can be arranged like so:

Ch1 - Aileron
Ch2 - Elevator
Ch3 - Throttle
Ch4 - Rudder
Ch5 - GPS mode (RTH/HOLD/OFF)
Ch6 - Pitch
Ch7 & 8 - PPM Max Encoder

Then from the PPM Max

Proportional 1 & 2 - Camera Pan/Tilt
3 Position 1 - OSD control
3 Position 2 - *Future Use*
2 Position 1 - Navigation & Beacon Lights on/off
2 Position 2 - Landing Light on/off
2 Position 3 - IR illumination on/off
2 Position 4 - Miniguns **Braaaaaaap**

The only potential issue I can see thus far is that the pan/tilt takes input from a joystick. For me this will probably have to be made to work with Head Tracking as the input (i only have so many hands!), that might be difficult however! the other option is to mount the joystick for the pan/tilt on the back of the controller allowing it to be operating by the fingers of my right hand (I fly helis with thumbs, an advantage in this case lol)

[Zeeflyboy]

Wow... just wow.

Look what came today! This is just even better than I had hoped for - the detail is insanely good... If I had known it was going to come out this well I might have tried for even more details lol. Remember those arrows on the screen buttons for example are only raised 0.2mm above the button (hopefully just enough for me to be able to paint them white)! Dimensions are spot on too so it looks like I managed to pull this one off - I'm one happy chappy! Just need to paint it now.

[Zeeflyboy]

And here is Juan having a test fit...

He's still looking fairly happy because he doesn't know that he's in for some major surgery over the next few days. The arms and legs aren't free moving enough, and the legs have too limited upward travel so they will be hacked apart and modified... ultimately the poor chap is going to be decapitated too. To add insult to injury (and I suppose, injury to injury) he'll finally have a screw inserted up his posterior... life can be cruel.

[wgt40w]

Has his mate (in the background) passed out with shock at the news of what is about to happen to Juan ??

[Zeeflyboy]

may well have lol

So, just disassembled a 1.8" photo viewer... quick test fit to see how it's looking! I checked looking through my FPV camera and I don't get any screen flicker, so that's good. The lipo will be replaced with a 3.3v power supply.

[W0LF]

That.. Is THE coolest thing I've ever seen

[g.collins]

looking good bud.
;) G

[Zeeflyboy]

So, been working a lot lately = not too much time...

However, a few small updates.

Firstly on the mechanical side of things:

I've been looking at mounting the mechanics in the fuselage, and I see some people just use plywood blocks to raise the mechanics up enough. The kit came with some stand-
offs, but these aren't in the right place for the T-rex 600 mechanics and hence why people do the plywood thing.

I thought I could attack this problem slightly differently so I have designed a mounting bracket that will go on top of the stand offs, and to which the mechanics will be attached. I'll be getting this machined out of aluminium.



and here you can see the stand-offs it'll attach to.




I'm also looking at pulling out all the linkages on the frame and running direct to swash servos... looks like it should work fine and it saves weight/removes slop and allows me to move the rear servo further in to clear the fuselage.... more to come on that later on.



And on the cockpit front:

I've been giving some thought to how to build a nice pan/tilt mechanism that can be stuffed inside a Torso... this is what I came up with. This will be printed out of the standard flexible and strong white plastic from shapeways for about €10.





The basic idea is this... the large piece on the right attaches to a round servo horn. You then insert a 10mm aluminium tube of whatever length is required into the hole. The piece at the back then mounts on to the top of this tube, and will be fitted with 3x6x2.5 flange bearings on either side for the tilt shaft. The piece on the left slots between the prongs and has a 3mm shaft inserted to keep it all together.

In the same way that I made a cut out in the tube for the cyclic elevator control, a cut will be made in this aluminium tube to allow a servo to be seated... this will then have a linkage running up along side the tube that attaches to the little tab at the back of the piece on the left and will operate tilt.

The whole lot then gets inserted into a hollowed out torso so that the top section comes out roughly where the neck  would be, and the camera gets mounted to the top.


And finally, something actually real rather than 3D modelled... I just got done painting my dash. This is going to be a special ops heli so I wanted to go for something that looked like it had been beaten to within an inch of it's life... unfortunately my artistic talent is somewhat limited and this is the result






The two big emtpy slots will be filled with LCD screen obviously, while the top right will be an AHI and the other two will be black with green writing. They'll be printed on some backlit paper in the same way my eurofighter screens were and then lit from behind by LED backlight. The LF, O,H, and R holes will be filled by LEDs as mentioned before. The LF will be flashing red when voltage reaches a pre-determined level, then O will be green, H will be orange and R will be red... indicating the state of the GPS mode in which the heli is flying.

That's it for now I'm afraid, baby steps!

[Zeeflyboy]

Here's a quick mock up of the dash with some screens photoshopped in...

[Zeeflyboy]

Too cool... can you sneak one out for me please? lol

So, it's my birthday and I'll play with my toys if I want to....

Got some little extra details for the boys, vests, knee pads and a better gun etc. Unfortunately I already broke the tip of the gun by dropping it... typical lol. I'll see if I can fix that. I had to do some cuts to the back of the seats in order to get them to clear the floor on the main body, and I also came up with a much better mounting system that consists of 3 very high tech lumps of plywood epoxied to the body onto which the cockpit can be mounted and screwed down. I think I'll add a middle support too as it does have a little flex as is.

Here you can see the rough seat cuts, plus note the position of the servo for collective stick movement.





Say hello to cyborg head. This is a small form factor Sony HAD II 600 tvl camera and will be replacing poor Juan's noggin.





Here's my dash with the auxilliary displays fitted - I first installed a little clear plastic then installed the backlit paper behind so you get the appearance of glass over the top when it picks up some reflections etc. I've pictured it here next to the dash that came with the kit for reference..





And finally the lads are chilling out for a test fit - really happy with the size of them, they look good I think. The doors on the fuselage will be cut away like the real version so you'll have a better view of the guys and visibility out the side will also be better for the camera.







My girlfriend just asked me how I'm going to paint it and I said I'll be buying an Airbrush for this one - she offered to buy it for me... what a girl!

[CurryKitten]

Just the fact that the camera is wearing a combat helmet makes this even cooler, and it was running pretty cool already.

Excited to see the next step... and even though your work-rate on this is amazing, I'll say it anyway.  "Work faster" ;)

[wgt40w]

Err, if anything was ever to go wrong between you and your girlfriend - may I have her number first - my birthday's coming up soon !

:-* :-*