Topic: HK450 set-up - First timer!

Hello all.

I bought one of Giant Cod's HK450s around half a year ago, only to discover a radio problem which prevented me from playing with it. Today, my new receiver turned up after a fellow RCMFer tested the previous one for me (only had one 2.4GHz Tx and Rx, so couldn't work out which was at fault) and tonight I had a bried play with the helicopter outside.

I hadn't really worked out suitable values for throttle and pitch curves until after dark, so haven't tested anything since. However, initial observations are that whilst I'm fairly comfortable trimming out the cyclic, I am running out of tail rotor authority before the balls on the training undercarriage leave the ground.

I am getting full movement of the tail rotor pitch mechanism from the servo, so in lieu of any personal experience of model helicopters, I can only assume that the headspeed must be rather too low (probably due to lack of throttle and overly aggressive collective thanks to no throttle/pitch curves) for the tailrotor to provide enough reaction to the torque.

What do the experts think? 

the best way saving time to explain is to watch/down load the finless bob videos for the trex

http://www.helifreak.com/forumdisplay.php?f=60
Ron

Yes, it sounds like your head speed is way too low. On an electric heli you can have a very crude throttle curve because the motor is largely self-governing (ie it runs at nearly constant speed and moving the collective simply increases and decreases the current drawn).

On my Trex 450XL the throttle curve in acro mode goes 100-90-100 as the picth goes from (IIRC, from memory) -12 > 0 > +12. This is in "acro" flight phase. For general hovering and landing I use "landing" flight phase which restricts the negative pitch to -2 degrees - this reduces the risk of boom-strikes.

I then use the master throttle limiter (set up on my E slider) to spin-up and spin-down at the beginning and end of the flight.

Your next question should be "should the throttle stick be in the centre for zero pitch or for a steady hover" (usually about +6 degrees on a 450). There is no right answer to this one - it's a matter of taste. I have the stick in the middle at steady hover in landing and acro flight phases, but switch to the zero-pitch option in "3d nutter b'stard" flight phase. I've programmed a 3 second transition for this flight phase so that switching to itr doesn't produce an elegant plummet.

£0.02 supplied,

PDR

PS - what did you think of the HK450 kit? I'm getting tempted to get one of the metal-blinged ones and using my 450 as a donor. I'm also tempted by that cheap 5-blade head...

 

Thanks Pete,

I think I'll stick with a girly set-up, with the stick in the middle to hover. I can see me wishing to go down the scale route rather than the 3D route which sounds like a recipe for a crash where I'm concerned! 

I'll have another play tonight and see how I get on with higher head speeds. I could take my tacho with me too to actually measure what I'm getting, and I'll get the pitch gauge out again.

Having not had a genuine Align TRex 450 I can't really comment too much on the HK450. I got one of the first batch of plastic headed ones for £29. For that money, compared to what Align charge for something functionally similar, I'm delighted. There are no instructions but Giantcod has a forum link to a build thread which gives photographic step-by-step instructions pitched at my lever and these were both accurate and easy to follow. The blades in my kit are a bit naff but I'm inevitably going to shorten them in a grass-cutting accident at some point anyway.

The tail boom didn't really fit into the plastic block that holds it onto the side frames and I gave the edges of the hole in the block the slightest chamfer and the boom could be pushed in. Other than that, it was fine. The canopy is a bit naff, but then again I think pod-and-boom model helicopters look inherently naff so personally would prefer the item to be as cheap as possible because as soon as I feel comfortable with the heli I'm going to dress it up in a scale fuselage.

There is a bit of movement in the flybar cradle and associated linkages on the plastic head. I expect the alloy one would be much better. If and when I break this one I'll probably buy alloy replacement parts.

I haven't really found cause for complaint on the supplied hardware either. Some say the Allen key screws are useless, but Mine went in, out and back in again without issue. (I managed to twist the drive belt the wrong way and have the tailrotor rotating the wrong way at first and other such schoolboy errors

Am I a little naive to consider building a fuselage from scratch to suit the larger HK600 with Motosport 5 bladed head? I've found 500 size scale looking blades (longer aspect ratio, less toy looking) but not 600. Must admit I haven't looked very hard yet. A 5 bladed tail rotor hub would be nice too. I've only found Century to have those yet, and they're both expensive and somewhat larger than I want for this. Hmmm...

I need a 45deg bend for the tailrotor transmission too.

I would have been out trying my new throttle/pitch curves but it's been drizzling all night, so I got out the pencil and paper instead.

From what I've seen of your handiwork on other things you've posted I can't see why you should have too many problems.  I guess heli bodies are only set-dressing anyway, as long as it looks right it is right (unless it weighs far too much).

I always fancied a scale heli myself...well I say always, in truth it probably began right around the time that I realised that I would never really be any good at helicopter aerobatics.

I had been thinking that the gyro may not have been doing very much for me, or that helicopters were simply very challenging to fly.

My initial hover attempts with new and improved higher head speed demonstrated that I had sufficient tail rotor authority, although I was constantly on the tail rotor stick and had to concentrate very hard.

It turns out that although I had read the gyro instructions, they weren't very clear about orientation (ok, and I made an assumption without checking).

I had the gyro measuring changes in aicraft pitch and trying to correct them with tail rotor.

That may explain why I was working so hard on the tail rotor channel 

Great thread Jamie, and so honest !
I'm thinking of putting an HK450 together but direct from Hobby King, (bit nearer for me, than GC); so all the information you share is really appreciated.
Gaspin

Being able to lie consistently is not a strong point of mine, so my usual tactic is to go in honest and defuse critics by firing off their ammunition before they can 

The HK450 seems really good for the money. It's probably worth going for the metal upgrade parts though. I think the HK600 will be perfect for the S-61R I'm drawing. I would really grudge paying Align (or similar) prices for a 600 sized kit full of carbon bling that either got binned or just hidden and a substantial number of mechanical parts (e.g. big impressive rotorhead and swashplate assembly) that needed to be replaced with a 5 bladed item anyway.

Paying HK600 money for a donor kit is far less cringeworthy!

Yes Good Thread..... 

I have two HK 450's flying (and a Century GL450 which amounts to the same thing now it has a lot of replaced parts), a third all HK450 about to be built with a Sikorsky Dragonfly body (50's Royal Navy Heli!!), one HK500 flying and two HK 250's, one complete but not fully set up so not yet flown, and one robbed for spares (for now) since BOTH kits were supplied incomplete and till Cod sort it I had to rob one to build the other.

All the HK kits were Cod bought      , but have some Hobby King bought gear in them.

What do you want to know................cos I probably will have stumbled over it and banged my nose a few times...........

Oh and re: the gyro orientation error...........yup, been there, I struggled briefly to get an IMax one working on a Skyartec Wasp because it didn't say it was a side on facing control one rather than a top facing control one like the GY401's...useless instructions, fairly good gyro!

I bent it last week. I had a dumb thumbs moment and landed rather positively. So positively infact that it bounced, did a half summersault and landed inverted 

It stripped a gear on one of the swashplate servos and bent the feathering shaft, but that's it. Spares ordered from GC at lunchtime on Friday for less than £6 posted, and fitted last night. 

It seemed to go rather well right up until I closed the throttle before reaching the ground  Tail rotor control was very positive but I found cyclic control to be much less so. Infact, it was positively vague with large stick movements to achieve anything and long delays before anything started to happen. Should I try moving the girlie weights inboard along the flybar a bit?

Never used any Girlie fly-bar Weights...............................not even on my now flying HK250 (which flies very very well, BTW).....

It's always surprised me how "gentle" the cyclics usually are, and I usually use as much throw as possible, but then my recent background was in fast wings with big throws and lightning fast roll rates.

What do you have the swash percentages set to?

I'll maybe try it with the weights where they are now (about half way out the flybar - actually, one spare feathering shaft's distance from the paddles  ) and it I still don't like it I'll lose them completely then. I can't remember for sure, but I think the swash plate percentages are set to 100%  I'll check...

Hi Bad Raven,
Taking up your offer of advice and apologies to Jamie, I have a HK401 B gyro sat in front of me, part of my order for a HK 450, of course no instructions were included; the following questions jump out,
1. Two switches are on the face of the gyro, one marked nor. and rev. ( DR at the bottom) no problems the other is marked DS with on & off positions. What is the function of this switch is it gyro rate versus gyro head lock or is it digital to analogue for the servo.
2. As a supplementary question is the gyro suitable for an HS 82 with out any modification ( I read somewhere that if the they are not compatible I will fry the servo.
3. Three leads come from the gyro, the third lead yellow control wire only, goes , I believe into channel 5 on my Futaba 9C set. What does it do and how do I control it.
4. Is the HK 401 position sensitive, does it have to face a certain direction?? I plan on planting it on the front of the radio tray.
Gaspin

Hi Mate(s)!,

OK, brief as poss........

1. If you look on Cod's Forum in the products documentation section (from memory) you'll find detail on the Gyro, including a printable label, same gyro, just not supplied labelled.  With a Cod one, scale this for your printer so it fits, and then I used waterproof sellotape to cover it.  The "DS" is the marking for Digital Servo, "On" being Digital, get this wrong and "digital" a non-digital servo and it won't last long!!

2. Yes, Gyro will work with a wide range of servos, more important that you have the speed and power you need though, and a set of robust gears that won't strip at the first knock of the tail..........I have HS 5245MGs on two, a faster Hitec one on one destined for more active service (bought from Giant Cod,)

http://www.giantcod.co.uk/hitec-hs5084mg-digital-tail-rotor-servo-19kg217g005sec-p-404726.html

3. Third lead is Gyro sensing to be able to change in flight between Rate (tail tends to weathercock and follows flight path) and HH (tails stays where rudder setting is on boot f not being commanded). Don't know specifically for the 9C and no time to look now......  NOTE...ALWAYS boot the system in HH mode THEN go rates if wanted.

4. Sort of (!), ideally place it with the base flat, control upwards, any way round that makes the lead run easy, on a PROPER gyro foam pad (Futaba and Spartan spares are sold quite cheaply). Traditionally the gyro on a 450 goes on the flat top of the boom clamp box, not essential to be there, but it's best if it's kept away from motor, motor wiring, and Rx if poss (which there gives).

Got to go................laters................

Dave

Many thanks to Bad Raven, for a quick reply 
Gaspin

Traditionally the gyro on a 450 goes on the flat top of the boom clamp box,

Whilst this is true, I've always mounted my gyro elsewhere (like underneath the tail boom or on the port side of the boom clamp box) because in the "traditional" position the gyro can often be smashed by flailing blades in a sub-optimal air-ground transition scenario.

PDR

Whilst this is true, I've always mounted my gyro elsewhere (like underneath the tail boom or on the port side of the boom clamp box) because in the "traditional" position the gyro can often be smashed by flailing blades in a sub-optimal air-ground transition scenario.

PDR

Those having sub-optimal air-ground transition scenarios of magnitude should note that afterwards the gyro is probably parsimoniously discombobulated and ready to randomly offer them an excitingly extreme but brief 3D experience , so it's probably better that it's smashed to smithereens to stop them putting themselves and others at risk............   

If the gyro is working when I take off then my helicopter is far more likely to crash due to my flying than from some randomly occurring fault.  I can't believe that normal practice is to throw away gyros after ever crash.  Maybe for the sponsored chaps flying at shows but everyone else? Pfft.

Well I crashed and my gyro is staying. The impact wasn't actually that hard. It when the helicopter came down from it's bounce and landed upside down that the feathering shaft got bent and a pitch link popped off.

If the gyro is working when I take off then my helicopter is far more likely to crash due to my flying than from some randomly occurring fault.  I can't believe that normal practice is to throw away gyros after ever crash.  Maybe for the sponsored chaps flying at shows but everyone else? Pfft.

Try reading what I wrote again.......................... 

You seemed to be saying that a crashed gyro is so likely to malfunction that it should be considered dangerous.

There must be something wrong with my gyros - they fail to stop working after crashes. Should I send them back under the Sale of Goods Act?

PDR

Where's the Irony smilie when you need it............   

It's over there with the silvery and woodey ones - it's the one with the tinge of rust on the corners.

PDR

There must be something wrong with my gyros - they fail to stop working after crashes. Should I send them back under the Sale of Goods Act?

PDR

you must have harder landings (crashes) than most of us 
Ron

It's a Double Negative, Ron................

Well, as a helli newby, I proudly took my new HK450 down to the footy pitch next door at 07:00 this morning, carefully put it down, religiously turned on the tranny, clicked on the throttle hold, connected the battery on the helli, stood back a little and fired up for a first time hover.
The blades went roaring round, more like turbine speed than helli speed, but undaunted I continued pushing up, nothing zilch no lift nought :embarrassed: :embarrassed: :embarrassed:
At the top throttle the blades were going so fast it was a real stress test for the copter. After checking the pitch curve and the physical movement of the blades for  pitch tilt, nothing was blindingly obvious, so went home defeated for the moment.
So I'm aware the pitch settings are terrible wrong but where's the blunder? I carefully set up pitch for -1; +4; +8 max I thought, throttle curve is 0; 80% and 85% max all set on a Futty 9C, seems to follow this on the bench. At the field the head speed seemed too high and obviously the pitch was not working as planned.
The only anomaly on the whole radio set up is that with throttle hold  ON  the swash plate drops to a low position ( giving -8 pitch) when the Throttle hold is clicked OFF the swash plate jumps up to its -1 deg position.
Motor is a reccommended Turnigy 2218/3450 and the ESC is a TowerPro 40amp also reccommended, I know cheap and cheerful, but fit for purpose.
Any advice gratefully received, I'll take it down the club on Sunday but would appreciate any face saving suggestions in the meantime.
Gaspin

Can you see the swashplate move as you increase the throttle stick? I had the opposite problem above. Mine got airborne far too early!

Hi Jamie,
I'll have a look later today, it certainly moved on the bench, but didn't check earlier as I was just amazed at the speed of the head.
The only good part, it got taken home without the slightest scratch.
Gaspin.

Hi,

OK.........

If the Throttle Hold is affecting Pitch, that's not just an anomaly, its got to stop pronto, and don't try to fly till it doesn't!

Maybe you have wrong settings on HOLD and CUT, as an EP(motor) is not the same as an engine?

Check what is doing what!

All throttle HOLD should do is to allow the collective pitch servo(s) to move the head pitch exactly as they did before operating it while holding an ENGINE powered Heli throttle at Idle so the clutch is disconnected ready to turn the switch back and continue using the engine (such as when doing Autorotations).

Throttle CUT should kill the ENGINE completely while still allowing pitch changes on the throttle (collective) stick, if it were an engine powered Heli the engine would of course be arranged to stop and then would be dead till restarted manually, but a motor will be able to restart if the switch is turned back off, so the two controls interact for an engine but effectively do the same for a motor.  

How is yours set, you need to look.

From your post:-

With the fly bar held 90 degrees to the main shaft, the throttle stick gives -1 at NO throttle, +4 at half throttle, and +8 at full throttle, I assume this is forward moving blade, gauge at half diameter.  While your static pitch settings appear OK, it certainly isn't doing this when "flown" if it sits there and screams.......it should be in the hover about half throttle stick movement due to the +4 and the amount of thrust from the throttle setting.

Initially throttle "curve" is best as a straight line, my 450's are set 0-100 straight line.

I have a more or less straight line pitch curve, too, in Normal, going -100 (in your case the -1 degree) to 100 (in your case the +8 degrees), but have tweaked up the centre area and above minimally so that the Heli hovers at centre stick dead on with a good comfortable head speed.  (minimally being +4% at centre stick on one of mine)

Suggest you disconnect the motor wiring, and then start by finding what is affecting pitch on throwing the throttle hold switch, once that's stopped, THEN re-look at the pitch settings?

Thanks Bad Raven,
I'll start working through your suggestions, let you know how it goes.
Gaspin

I'm wondering if maybe you had one mode programmed fine but before the flight you had inadvertently hit the flight mode switch and switched it into another mode, one which wasn't programmed and so had no pitch curve set at all.

I'm wondering if maybe you had one mode programmed fine but before the flight you had inadvertently hit the flight mode switch and switched it into another mode, one which wasn't programmed and so had no pitch curve set at all.

Possible I guess, but Futaba Tx's in my experience at least all come with straight line "Normal" settings for all modes as default, so unless you specifically program Idle up settings nothing will happen different to normal, AND they have the other modes inhibited as default anyway, so throwing a switch would do nothing.

Thanks for the thoughts Mark, but although raising my hopes for a while on checking it was in the correct normal position.
I've now straightened the curves for pitch and throttle, reduced throttle to mid point (60%) and increased movement on the swashplate, now looking at -1.5; 5; and 9.5 for pitch, just fired it a up little bit in the bedroom and the swash plate is moving with the throttle input.
Played with the throttle hold, (throttle cut is INH), the only point of convergence is at 50% throttle, on the Futaba set there is basically only and off/on adjustment, POSI % seems to make no difference, what I see as the jump is the difference between my throttle/pitch settings and full range.  The radio manual gives no enlightenment.
I'll spin it tomorrow morning and report if I can get a hover of some sort.
Thanks for all your suggestions.
Gaspin

If your throttle hold switch causes the swashplate to go negative and stay there is it possible you have the throttle and collective channels swapped?

Also I'd be looking for -5deg to +12 deg as a starting point on the pitch range. -1deg may make it difficult to decend, and with a top end of +8 you could find you need over 3/4 throttle stick to hover. My 450sl hovers at about 6 degrees.

PDR

go into the advanced menu and alter the pitch curve in throttle hold
this will stop the swash jumping

If your throttle hold switch causes the swashplate to go negative and stay there is it possible you have the throttle and collective channels swapped?

PDR

YES, good thinking, that's possible................

Plug a spare servo (rather than the ESC) into the throttle channel so that you can then test it on the bench and see what it's doing.

PDR

Thanks guys for all the help, I managed a rather ragged hover today, so the main stuff is in the right sockets. I now have issues with the rudder authority, I think head speed related. Maximum left rudder will not bring the tail back. So I'll try some trusted advice from the club tomorrow. (Yes; the gyro does work and in the right direction).
Life as a fixed wing flyer was so easy, not used to having to engage the brain so intently for this rotary stuff.
Thanks again for your help, I'll keep you appraised of progress.
Gaspin