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Confused about 450 Sport Mechanical Blade-Pitch Adjustment

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Confused about 450 Sport Mechanical Blade-Pitch Adjustment

Old 08-23-2010, 07:32 PM
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Default Confused about 450 Sport Mechanical Blade-Pitch Adjustment

<span lang="">

...and a little bit hacked-off!

I ordered a TRex 450 Sport with a Fuytaba GY401, 1 * Futaba 9257, 3 * ACER D-12MG, DX6i, batteries, charger, tools, plus a few other bits from a very well-known UK supplier. I also paid a build &amp; setup fee.</p>

I finally took delivery a few days ago. Thankfully, I'm not the sort to rip-open the packaging and try to fly straight away. Instead, I've just spent 2-3 days familiarizing myself with the new radio and checking-over the model. I deliberately took my time over it so as not to reach any hasty conclusions. Also, never before having used a pitch gauge or set-up a CCPM head I had a bit of a learning-curve.</p>

By now, I've watched the Finless Bob videos 'til I'm sick, and scoured the many forums available. I feel like I'm now ready to report my findings on the mechanical setup of the model that arrived here on Saturday morning.</p>

The first thing to notice was that the Futaba tail-servo was incorrectly positioned on the boom so that the servo-wheel ball-link was about five degrees off-90 meaning that with anything above about 20% left-stick on the rudder, the servo was binding... noisilly!

I guess it just might have happened in transit but then the screws were still tight and there was no sign of damage to the boom paintwork so I'm sure it wasn't forced into that position. But I guess, if it had been only that one thing, since it was easilly fixed, I could have offered the benefit of the doubt and thought no more about it.</p>

But there was more. In order to check things out I fired-up the electronics using an Rx pack since the ESC to motor connectors were in heat-shrunk sleeves, meaning I couldn't use the BEC without powering-up the motor.</p>

I selected Idle-Up and, although I'm not sure it was really necessary, I edited the throttle curve for a linear 0-100% response to match the pitch curve.</p>

I attached the pitch-gauge and measured blade-pitch at half-stick... I got somewhere between 2 &amp; 3 degrees negative pitch! Initially, I doubted my own measurement. I spent the next day or so checking the forums, re-measuring, reviewing the how-to videos, remeasuring, going round and around the radio settings to be sure I hadn't missed some sub-trim, a servo direction or swash-mix setting, etc, etc.</p>

The one thing I did not do was start adjusting link-arms. I left the mechanical-setup exactly as it was when it arrived, but rather, tried to use the radio to arrive at a zero-for-zero pitch response, either at the mid-point in Idle-up, or at the low-point in a default linear curve in Normal mode.</p>

The pitch-deflections I continued to measure, allowing for upto 0.5 degree error, were always around...</p>

1 2 3 4 5</p>

Idle-Up 0% 25% 50% 75% 100%</p>

Pitch -11 -7.2 -2.7 +1 +5</p>

Normal 40% 45% 50% 75% 100%</p>

Pitch -4.2 -3.4 -2.5 +1 +5</p>

The only way I found to get zero pitch at midsticks was to have lage sub-trims and set the midway pitch-curve point at about 67%. Not very convenient. I would also have a very eneven pitch range!</p>

It wasn't until this evening (Monday) that I finally got out the ball-link pliers and started to adjust the setup. As far as I could see, I needed to bring-up the swashplate to push the pitch range evenly about zero. Also, to even out the flybar cage that looked a bit wonky... maybe a degree off-kilter... which seemed easiest to correct with a turn taken off the elevator-servo link rod.</p>

I then ended-up adding two-turn lengths to all three cyclic servo link arms to shift the pitch-range.</p>

Now I can measure the following...</p>

Idle-Up 0% .. 50% .. 100%</p>

Pitch -8 .. 0 .. +8</p>

This is great but now theres a another problem..,. I expect you spotted it... and this is what I'm confused about. Looking at the PRO head, you have a pair of adjustable top-links between the mixing arms and the blade holders. Adjusting these, I guess, allows you to alter the blade pitch directly. But on my SPORT head these two links are fixed-length. To adjust the pitch, I have had to move the swashplate, and in doing so I have put the ends of the washout arms out of allignment. I can see the other adjustable links between the inner swashplate and the mixing-arms which I could have used to alter blade-pitch, but that would have made the flybar cage uneven?</p>

I just don't see, with fixed length top-links, how you can alter blade-pitch without getting either the washout arms, or the flaybar cage out of allignment?</p>

Clearly I'm missing something. Any help appreciated.</p>

Although it is irritating as I had expected all this to have been done already, I suppose I am gaining in experience. But mainly, I'm just so glad I didn't try to fly it out of the box. Could have been pretty nasty!</p>

 </p></p></span>
Old 08-23-2010, 07:52 PM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment

I have built a sport, and I had to adjust the link from the servos to the swashplate to get zero pitch at mid throttle. You shouldn't touch the top-links to adjust pitch (that's one reason they are fixed). Those are meant to adjust tracking of the blades (same level).On a 450 Sport, it's the mid-links that are used to adjustblade tracking. It is the swashplate that dictates the pitch. Note that the servo arms should be in the middle, so avoid using trim and sub-trim to adjust pitch. Use those to level the swashplate once you get things right by adjusting links.
Old 08-23-2010, 08:44 PM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment

<font size="4">Thanks mate

Good to know its not just me.

Any thoughts about the washout arms not lining-up, there is about 2mm difference in height between the washout arm ends?  But the mixer-arms in the flybar cage do look level.
Is this a problem?

Rich
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Old 08-24-2010, 05:41 AM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment



I found a discussion on this thread that talks about a problem similar to yours on a Trex 450 Sport:

http://www.rcheliaddict.co.uk/setup-...port-help.html

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Old 08-24-2010, 06:30 AM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment

Can't blame you I be a bit ticked off also, but good for you for double checking EVERYTHING.
As far as adjusting the swash for 0 pitch your correct in assuming you'll have to adjust the links betweed the swash & mixing arms. It's the same way on my 250se. I prefer the adjustable links on the blade grips myself. They are not available on the 250 however if you get a pack of the links for an older SA/V!/V2 450 they are adjustable & will work just fine.
As far as the links go, I have to be looking at it to be sure but I believe shorting the link increases pitch and lengthing it lowers pitch. You should be able to even it out with this. It took some trial & error with my 250, but got it after a few tries.
Any other questions you can e-mail me direct at [email protected] if you want or just repost in this forum
Jim R
Old 08-24-2010, 03:37 PM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment

Rich,

Good to see you took your time to check everything out.

Given that you paid for build and setup, I'm sure the Brits would be interested in the vendor, so come on name and shame.

There's a good bunch of guys over on RCheliaddict, quite a few in your area should you wish for someone to give it a once over before you commit to that first take off.

Good luck with your heli

Nip
Old 08-26-2010, 05:48 PM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment

Hi Everyone

Many thanks for all the help &amp; support.  Couldn't post any sooner cause I'm changing broadband suppliers at present. I'm posting this from a pay-as-you-go BT hotspot!

I thought long and hard about whether or not to name the vendor?  I guess I wimped-out a bit.  The trouble is that they have an insanely loyal fan-base and  I was anxious about becoming a pariah!  The whole story is that I had objected (very mildly) when, a week after paying around 700GBP, I  was finally informed (because I asked) that the resident builder was off on holiday for a fortnight.  I guess I felt that they should have told me that BEFORE taking my money.  I posted to their forum saying that when that amount of money is involved, the onus is on the dealer to keep the customer informed, rather than the other way around... No name calling, or vitriol!  I simply suggested that they publish a list of current build/repair jobs so that potential customers can choose for themselves whether to wait, or go elsewhere. 

After this, relations were frosty to say the least!  Then, 17-days after I paid them, plus another 31GBP for a Saturday morning  delivery, the model arrived as described above.  Draw your own conclusions.

To be fair, I have every reason to believe that the vast majority of their customers are very happy.  I suppose the lesson is that it is a mistake to publicly criticize someone who is holding all your cash!

However, for the sake of of other UK flyers, these guys sell helis in the North East of the country.  Anyone interested should be able to work it out. I expect you know of them Nip.

Anyway.  Thanks again &amp; Laters...
Rich
Old 08-26-2010, 05:57 PM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment

More inportantly did you get your heli sorted out ? If you haven't let us know & we'll try to help sort it out with you
Jimmy R
Old 08-26-2010, 06:12 PM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment



As far as my setup is concerned, as soon as I have the chance for another try, I will post again and say more. All of your posts are really helpful and thanks also to JimR for offer of direct help.  Until I get my new broadband installed I can start emailing again (just waited 10-days to have phone supplier swapped, now have to wait at least  a few weeks until BeThere can connect me!) 

For now it's back to the CB180Z ("...your so big!  ...it's so tiny!")

Glastnost to you all

Rich</p>
Old 08-27-2010, 03:49 AM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment

i wouldnt replace non adjustable links with adjustable ones. believe me, the fewer places for error the better. you need to adjust ur links untill your head is completely square at mid stick with a 0-25-50-75-100 pitch curve. ur mixing arms should be straight and lined up. ur flybar cage square and ur blades at 0 pitch. first you need to keep your swash level. if you dont have a leveler there are other ways to do it, but a swash level tool is very handy and quick. once your head is square, ur blades should be pretty close to 0. you might have to make a half turn or turn here and there. but it should be close. you want your servo horns to be at 90* also.

you mentioned you changed your idle up throttle curve to 0 25 50 75 100 to match your pitch. this is incorrect. it should either be flat or v curve in idle up. maybe 90 - 100 flat what ever you like. or a v starting at 90 -100 at bottom stick dropping down 3 to 5 degrees at mid stick and then back up to the bottom stick value at top stick. like 100 97.5 95 97.5 100, or 100 inh 95 inh 100 . personally i like the flat curve.

you might want to watch those finless vids again too lol. especially the beginner set up 101 vids. it specifically goes over setting up the head and then goes through the radio. some things may be slightly diff than the sport or dx6i, but its basicly all the same. i started the same way.

as far as your helis build, its not uncommon. pretty much anything rtf needs to be gone through. believe me, once you crash and rebuild a few times, youll never buy a preassembled heli again. so much better to build it yourself. it may seem complicated but just watch the vids at first and follow along. its not as bad as it seems. before long you will be able to tear it down and rebuild blindfolded.

when ever you get ur head set up, all square and zero. if you want more pitch on the top and bottom you need to adjust your swash mix in ur tx. find your swash mix and it will have ail ele and pitch. if your pitch is a negative % make it more negative. if positive take it up higher. basicly disregard + or - and increase the number (taken that your pitch is indeed moving in the right direction). increasing the ail and ele will give you more cyclic range in your servos. thus reducing those % will tame the heli down.

that reminds me, hopefully all of your servos are moving in the proper directions. just wanted to throw that out there just to be sure.

hopefully you get everthing figured out and get going. i started with some training gear just kinda hopping on the pavement. after a week or two i could sustain a hover pretty well and throw in some piros. hang in there man, you will get it.
Old 08-28-2010, 05:40 PM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment



Thanks heaps to baurwin</p>

As it goes, there is another chapter to this saga.  In fact, when I made my last two posts it had already begun... but, since I was waiting for a few spares I decided to hold-off and give you the full story all in one.  It's a wierd one!  Or it seems so to me.</p>

Before I go ahead though.  One point, I was never intending to fly with a linear idle-up throttle curve.  At that point I was unsure whether an exponential throttle-curve would throw-off the mid-stick / zero-pitch measurement?  But I'm a bit clearer about things now.  Also, CCPM mixing and servo directions all ok thanks to Finless; my swash-mix goes positive/negative/positive.  Good advice though baurwin, thanks for asking.</p>

Anyway.  I guess my impatience had got the better of me and, having balanced &amp; fitted a set of 310mm woodies, and fixed a training-rig to my skids, I decided to spin-up in the living-room, just enough to see the skids lighten and maybe get an idea of whether the blades were tracking right?  Dumb dumb dumb dumb dumb...</p>

Well... I got to about... 30% throttle when there was an almighty BANG... like a really high-voltage discharge... or maybe small-arms fire?  Suddenly, the air was full of flying wood-chips... my PC keyboard took a hit... dislodging both the Shift key and Spacebar.  And my beautiful new heli was on it's side... in spite of the training-rig... with a very unhappy looking flybar and the main shaft on a loop! </p>

Even now,  I'm still not entirely sure what happened?  My best guess is that one of the plastic clips that held a training-rig rod to the left skid, which I had re-inforced with a nylon tie-grip, must have been under tension (from the nylon tie-grip) and gave-out from the intense high-frequency vibration?  Looking at it now, I can see that this would have put a serious JOLT into the whole machine which (I think) sent the flybar into the main rotors?</p>

This is the only way I can really explain it to myself... seeing as this clip was also broken during the incident?  The only other explanation that I can imagine is that the woodies gave-out under the strain?  But at 30% throttle, with a standard linear 0,25,50,75,100 throttle-curve and 40,45,50,75,100 pitch-curve in NORMAL mode, surely they can't have been anywhere near their max RPM rating?</p>

In the end, thankfully, the only damage was to the flybar and the main shaft, and worst of all (in terms of cost) the canopy.  But a few days later, for less than 30GBP I had replacements and I began the repairs.  And you know what, apart from the risk of injury from flying splinters... I am glad it happened!  Because now that I've had the gears out and the shaft and the flybar and the head off, I feel a lot more confident about working on it.  And you are bang-on right baurwin, I probably wouldn't go for RTF again.</p>

So having rebuilt, the next thing I come to is setting-up the head again and this time from scratch.  At this point I had my first bit of genuine luck (apart from meeting all of you excellent fellows that is); in amongst a box of old assorted stainless steel gears and links and chain drives that I inherited when I moved into my current home, I found a brass collar with an outside diameter of about 25mm and a slot in the side which is easilly big enough to get the main shaft through.  It is machined dead flat top and bottom and, as chance would have it, when I insert it between the swash and the top of the main frame, the height is EXACTLY enough to bring the mixing-arms into PERFECT alignment!!!  So I now have a swash-levelling tool.</p>

I was able to re-adjust my servo link-rods so the servo arms were properly centered, slap-on the swash-to-flybar links and after a bit of juggling get zero-pitch for midsticks with a level flybar cage too!  When I checked the pitch-range I realized that my swash was probably a fraction too low but was able to cure this with some reasonable sub-trim settings (nothing over 20).  At 60% swash-mix I get +/- 8 degrees, with a swash-mix of 70% I get +/- 10-degress.</p>

So, last night, after thinking about it all day, I decided to spin her up again; in any case it's too windy to fly here at the moment so this is the best I can hope for right now.  This time I used the kitchen since there is a corner I can shelter behind (lol)... that bang has left me feeling a bit didgy!</p>

So I let the soft-start wind-up and then slowly brought-up the throttle at half-a-stick-division a time.  There was a tiny bit of low-frequency vibration early-on but that soon passed and then the top of the head looked solid as a rock.
 
Everything sounded fine and pretty soon I was at the fateful 30% mark.  Still nothing bad happened.  I knelt down and, holding a towel out in front of me (to ward-off flying splinters!) had a peek at the rotor-disc side-on... I had a nice flat disc the same thinckness as a single rotor blade, with no sign of any separation between the ends of the blades.  So far so good.  I increased the throttle to the next division (one before midsticks) and I saw the skids begin to jiggle just a wee bit so I slackened-off til it settled and left it running for about 10-15 minutes.</p>

I kept checking the disc edge and it was still thin and solid.  One thing I did notice was an occasional (i.e. not regular) slight drift up then down of the entire disc-edge.  I don't mean that one blade went high and the other low, I mean the whole disc edge remained the same thickness, but moved upward a few millimeters, then back down again.  The motion was very slow and gentle.  I don't know if it's correct or not, but I wondered whether this was the result of i) ground-effect pushing back against the rotor-disc, coupled with ii) the fact that there were cupboard doors to the front and either side  about 2-3 feet away?  Anyone have any thoughts on this?</p>

So, after about twenty minutes in all, I slowly throttled down again and let the rotors slow to a stop.  I was amazed to find that the motor was not hot at all (I could touch it without any problem) and the battery was still cool!  My little Walkera CB180Z gets pretty hot after a single pack!</p>

And there you go.  My first successful engine test.  I'm praying for a windless, rainless morning so I can go out to the New Forest and have a go at hovering.  I freely admit to being nervous.  I've been practising with G4.5 for weeks and weeks, and I can fly my CB180Z a bit (hovering, stall turns, piro's) but that is a fixed-pitch and has stabilization; even so, it took a couple of weeks of practice to stop myself over-correcting and get to a stable hover.  There is even room in my back-yard to practice hovering &amp; orientation with the 180... but I'm not sure about trying to hover the TRex out there?  I measured it and I've got 6 rotor-disk diameters in each direction, i.e. just over 3m square.  Does anyone think this is enough to try a hover for the first time?  I just don't know what to expect?  What do you guys think?  It would be much more convenient and I could practise more often but not worth it if I'm gonna be all over the place.</p>

Once again, thanks to all and happy hovering.</p>

Rich
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Old 08-28-2010, 07:31 PM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment

Congrats on geting it straigtnened out. Not seeing the heli but going by what your describing I'd say it's ground effect coupled with root wash coming off he wall. My suggestion is Don't try doing a hover in the house again. you could wind up with some serious damage to you & your home. Personnally I'd find a bigger area for your first hover, More rom to make mistakes without getting overlly nervous and realy overcorecting. Try pushing it around on the training skids for a few bateries until you get used to it. Try a keep it within a 4 foot box or so. Just some techniques I learned from Radds School of Rotory flight web site. You might want to check it out.
As far as the nerves go I still get them every time I try something new. Got my first inverted hovers down yesterday and was shacking like a leaf by the time I brought it down LOL
Good luck & have fun !
Old 08-28-2010, 07:57 PM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment

Nice one mate.  I  can just about manage an inverted fly-past in realflight... but in reality! Jeez, I can't imagine it.  Shakin?  I think I would need to be sedated!

You're right about the backyard.  If the wind gods are smiling in the morning, I will head for the forest and try-out your suggestions.
Cheers

Rich


Old 08-30-2010, 04:11 PM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment

Rich,

No idea if this is near you but there's a whole bunch of guys fly indoors from time to time and outdoors weather permitting.

Indoors @

Abbotswood School
Ringwood Road
Totton, Southampton, SO40 8EB

Outdoors @

From the M271 come off the other side to BnQ and head for Lordshill.When you are at the David Lloyd traffic lights hang a left and first right. Half a mile up on the right is parking.

I understand what you were saying about the consequences of posting your experiences on the vendor's forum.
Extremely odd place that indeed. If you meet up with the guys from Southampton, explain the situation and once they've stopped laughing, you'll get a totally different response.

If you want any more info, drop me a PM. Only to pleased to help.

Nip
Old 09-01-2010, 11:14 AM
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Default RE: Confused about 450 Sport Mechanical Blade-Pitch Adjustment

Sound as...

Will PM you directly.

Rich.

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