Ping-pong balls and bamboo?

[applematt]

After a couple of days taking servo's out and putting them back in, measuring control rods, ensuring the swash moves in the right way according to control inputs... yada yada yada the heli actually works and takes off, well takes off in the loosest of terms jerky bunny hops around the front room at best!

The swash still isn't working as it should, so to get the thing off the ground hovering while fine trims are made I'm thinking of using a training undercarriage to cushion those panicked skewed landings!

Can anyone recommend a suitable set of training landing gear for the mini t or should i make my own from the above materials?

Back to the swash problem...

The hs-56hb's servo horns do not fit the center point, therefore i cant get 90deg for any of the 3 servos, each one sits in a slightly different position... So, after ensuring the control rods were to book i began adjusting them to accommodate the differences.

What i now get is, much better than before but still a problem, alternating swash angles as i increase collective. End points for each of the servo's have been adjusted as not to stall the servo or overload the head controls.

What this does give me is a real problem as i increase the collective. To compound the issue the wood blades are out of balance, but weigh the same (25g). CoG is slightly out between each blade by about 5mm - i spose this would cause head wobbles???? Is it worth balancing the blades or just get a new set?

Above all these teething issues the tail remains fairly solid with another hs56hb via the 401... i've dialed in about -50% expo for the rudder (sorry yaw)as all the travel was about the middle of the stick... set +65 / -60 for the HH/normal mode... and a delay of about 50% on the gyro pot - and as this servo is not digital the non digital switch has been selected.

Any suggestions for any of the above please feel free.... and thanks for taking the time to read this rabble... its been a long while since i spoken to anyone... helicopters ay who'd have'em!


Regards,
Matt

[Steve]

Most servos have an odd number (rather than an even number) of splines on the output shaft, so by rotating the arm through each of its available positions, you should find one that is spot on (or VERY close) to the 90 degree setup that you're looking for.

[Philimon]

Hi, Matt. Welcome to the forum and congrats on your purchase!

Its really important that you get those servo horns perfect when using eCCPM, which I think your heli has, as I guess its a mini Titan? Failure to set them so at 0 degrees pitch is going to give you all sorts of collective/pitch couplings, as the geometry will just not be right. I'd start again and, with zero subtrim and 100% endpoints, rotate the servo arm on the spline to get it close. Feel free to use a little subtrim to get that last 5% right so that is perfect. Re-set the pushrod lengths.

You do need to balance those blades to have the same lengthwise CG. There is a lovely article on www.trextuning.com about blade balancing. I suggest you go there, check it out and follow it step bt step.

People here do prefer digitals for tail servo's, but I've also used the 56 on the tail of a mini elecitric to reasonable effect. It will be fine for hovering and a some FFF, but you'll soon notice the need for an upgrade to digitals when you start doing some more serious things, such as backward flight etc.

As for training gear, you can save a few bob by making them as you've described. Personally, I prefer the store-bought versions as they tend to use carbon rods and have a central hub that places these at an slight downward angle, giving a little of a shock-absorbing effect for those hard landings - most useful when doing little bunny hops. Do a search through your favourite online local hobby store and something will turn up for around £10.

Good luck, and don't be shy to ask.

Regards
Andrew

[Kwickkwack]

Hi Matt
Is the heli a Mini Titan as Philimon asks, if it is I am amazed you are having so many problems, I bought an ARTF model with the basic TT servos, which as a inexperienced flyer are fine, the model is very stable and smooth, and hovering is as easy as my Raptor 30 no question.
What radio do you use?

[applematt]

Thanks for the feedback chaps!

Its a mini titan kit with esc & motor!

The radio is futaba 6ex 2.4ghz

All 4 Servo's are hitec hs56hb and futaba 401 gyro...

The servo's are rubbish they are the worst i've ever purchased for 90° alignment... i've tried different horns and selected the best matched servos for the ccpm i have, and used the sub trim to take up the 1 or 2° difference across the pitch, ele and ali servos.

The main problems seem to ocurr with the speed of the servos, they are not matched across the range - i tested them in acro mode just to ensure the 3-s heli mixer settings wasnt messing about with them - out of the model.

I also noticed that the center point of the servo in acro mode is no the same as in heli mode when 3-s is selected... anyhow i've found the best center point for each of the servos now - just travel rate to play with!

All ccpm servo mounts needed to be drilled for my servos, as the central mounting hole didnt match up with my servo mounts - which was a pain

I think the remaining stuff comes down to fine tuning and time!

The tail servo will deffo be upgraded...

[Philimon]

Sounds like you're getting there. I've only used HS-65MG's on collective before, and had no problems with them. I hope you'll come right, although I'm a little concerned that you've got speed consistency issues. Perhaps a call to the supplier is in order?

Good luck!

[Maverick]

I made a training undercarriage from two carbon rods and some cheapo multicoloured ping pong balls for about £3.

Here it is on my Eolo while I was still setting it up:-

[chipbury]

I used two bits of 1/4" wooden rod with small drawer handles on the ends .
It looked a bit odd but it served me well, repairs were easy - just cut another length off the 2m section when needed (quite often ).