Catching up on v120d02s

[BHChieftain]

I have not touched my V120d02s in about a year (been focusing on the protos 500). Getting ready to tune up my 120 and stocking up on spares-- any major design developments on this bird since last year?

Also, who is your favorite vendor for parts lately?

Chief

[BHChieftain]

Despite my better judgement I ordered a bunch of spare servos which should keep me airborn for about a year when combined with the rest of the spares I have.

Just finished tuning up the bird-- had a buzzing from a bearing, thought it was from the main shaft and ended up swapping swash plate, main bearings, then gluing in main bearings... turns out the buzz was from a bad bearing in the tail and the sound was travelling up and "appeared" to be coming from the middle... swapped that out and back to silky smooth flying.

Chief

[ChitownMatt]

Chief,
I always check to see if Bob at helircstore, has what I am looking for first.

However, I have ordered a few times from this guy in china:

http://www.chinesejade.com/walkeraV120D02S.htm

He ships quick.

Also he stocks servo gears for replacement so you don't have to replace the whole servo. The replacement gears seem to be better than the stock gears. Servos I have fixed seem to last longer than brand new.

But to be honest, I have gotten good enough that I don't really have many "unplanned" landings anymore. I don't try anything new IRL that I haven't worked on 99 million times on the sim already.

Its taken me a few years, buts its really great to actually be able to "fly" one of these things instead of just trying not to crash. lol.

[BHChieftain]

I fly my protos500 great at the field, only 5 crashes in my last 300 flights. But I just get stupid with the V120 and race it around my backyard course. I'll post some of the circuits I do back there-- I need to fly through trees, under bushes, avoiding paver stone planters and a small pond... stupid fun. I probably slam the heli into something or clip a branch one out of 10 flights and half the time I just pick up the helicopter and take off again. Damage is either broken blades or stripped servos and broken landing gear.

Chief

[ChitownMatt]

No sooner do I brag about how good I'm getting do I go out and bust'er up on my first battery. Lol.
Oh well... Just a stripped servo.

[sco88]

Interesting question chief!

I have a similar one - I've just got back into flying my D01 after its been in the hanger for a year or two. It flies great but I'd like a similar sized CP - what's the latest from Walkera that might fit the bill?

Simon.

[BHChieftain]

Seems the best of the Walkera micro fleet is still the V120D02S.

However, if you are not super-invested in spareparts, walkera radio, etc, it looks like the best small CP on the market now is the Blade 180. I was on the fence on buying that or keeping my V120 up in the air, but I have a good supply of parts for th V120D02S and decided stick with that platform for 2015.

I had the V120D01 fixed pitch-- that was actually the first heli I learned on-- a nice little bird. The V120D02S is bascially the same design but CP. Much more rugged than the V120D02 (without the S). Skip ALL of the other V120 models (03, 05)...

I wish I read your post last week-- I just threw away a bunch of D01 spare parts and blades...


Chief

[sco88]

Thanks chief - after a bit of research I'd come to the conclusion that the d02s might be the one for me - would have to invest in yet another radio though - most likely the devo 7.

I will check out the blade 180 though!

Thanks again for your reply,

Simon.

[sco88]

That Blade 180 looks the business and is attractive because I think it would bind with my DX6i but in truth it's pretty close to my Gaui 200 and is a bit too big for my indoor flying space.

Simon.

[BHChieftain]

I had a gaui 200 (flybar)-- great one!

I can't complain about the V120D02S. The design is very good, it is easy to fix, and if you add a tail clutch modification you won't strip tail gears. It is still big to fly in the house IMHO, but it is a great backyard flyer.

Chief

[sco88]

Yes I remembered you had a 200 around the same time as I got mine only difference was I went flybarless.

Simon.

[sco88]

Hi Chief,

So I went and ordered a d02s - hopefully it will arrive tomorrow in time for Christmas ;-). Any chance you could share your throttle and pitch curves etc. to get me started.

Cheers,

Simon.

[BHChieftain]

Hi,
The most important thing to do is to mechanically set up the bird correctly. I will fly fine out of the box on stock setup but it is kinda a non-standard setup and if you crash you'll have a hard time replicating it.

I posted this on RC Groups and made a setup video --this procedure is the standard setup for any CP heli and works great on the V120:

http://www.rcgroups.com/forums/showp...postcount=2314

(copied from that post)

After inspecting the mech setup from stock, I saw a *lot* of binding points, and the servo arms at 50% were way off, so I decided to completely reset the mech setup.

I found this video for M120D01 setup and applied it to this bird. Only difference is the swash moves in opposite direction due to the trailing edge bladegrips...

See post #3 in this thread:
https://www.helifreak.com/showthread.php?t=305064

Here's what I did:

1) Setup TH curve to be like an idle1 curve, enter TH
2) Turn off the flybar gyros at the RX
3) Reset the servo arms to be as close as possible to 90degrees at 50% throttle. Neat tip from the Helifreak video is you can actually use Pitch subtrim to finetune (no gyro control on colletive pitch). There still is no ability to adjust each servo independently, but if both arms are slightly low, you can use pitch subtrim to better level them, or make one a little low and one a little high vs. one dead on and 1 way off.
4) Reset the servo to swashplate links so the swash is level and in the middle of the mainshaft movement range
5) Reset the bladegrip links to relevel the blades to zero pitch at 50% throttle
6) Use TRAVELADJUST to reduce the max travel at Max Throttle and Min Throttle to ensure there is no binding when adding cyclic. I really needed to dial the range back to avoid all binding! Note that there is not only binding at the swash collars, but also at the bladegrip links (they can hit the followers), and also the antirotational pin when applying max forward elevator at max negative pitch. Note, only use Travel Adjust on the "PITCH" channel (which is collective) as there is no gyro control there. Back the swash away from the high and low points until there is no binding when also applying full cyclics.
7) Edit Throttle and pitch curves to be like a normally set up heli for Normal and Idle.


For Throttlehold and Idle 1, midstick pitch = 0, at low stick, -100=max neg pitch, +100 = max positive pitch.

For my normal pitch curve I make my low point (-100% input) = -40% output, which should be around -5% of pitch or so. Midpoint (0%input) = 50% output which is zero pitch. High point (+100% input) = 100% output which is 12degrees pitch (I'm eyeballing that-- I don't use a pitch gauge for these small birds).

Here's a video showing some of the adjustments I made and the binding points to watch out for. Just did a test flight and all is well.

V120D02S mechanical setup (3 min 42 sec)

V120D02S mechanical setup (3 min 42 sec)

Cheers,
Chief

[sco88]

Chief,

Wow that is super helpful - thanks very much for taking the trouble to post that!

Wishing you a happy Christmas and prosperous new year,

Simon.

[BHChieftain]

Merry Christmas!
Chief

[sco88]

Hi Chief,

Hope you don't mind me keep pestering you with questions, I've set up throttle and pitch curves but am confused by the throttle % setting shown on the display (devo 7).
At low stick and in throttle hold the display shows -20%, at low stick and in normal mode the display shows -12% and the rotors are turning - I can't find where I set this 12% value at low stick as the throttle curve is set to 0% at this stick setting?

Simon.

[zadaw]

I think the biggest development in the past year is the availability of the gy280rx which is a drop-in replacement for the Walkera receiver. It is a combined DSM2/Vbar clone unit. Those who have tried it have reported a massive increase in 3D performance over the stock receiver.

http://www.banggood.com/Flybarless-S...-p-917714.html

[BHChieftain]

Originally Posted by sco88

Hi Chief,

Hope you don't mind me keep pestering you with questions, I've set up throttle and pitch curves but am confused by the throttle % setting shown on the display (devo 7).
At low stick and in throttle hold the display shows -20%, at low stick and in normal mode the display shows -12% and the rotors are turning - I can't find where I set this 12% value at low stick as the throttle curve is set to 0% at this stick setting?

Simon.

I have heard the devo7 is very cryptic on how to set... I don't have that radio... maybe somebody else can pipe in on that one!

Chief

[SkyKraken]

Having put a gy280 in v120d02s v2 I call tell you from experience its not a massive anything over stock except expense.

Other than pirouette comp, there really isn't all that much gained.
A well setup stock v120d02v2 can piro flat enough, if the time is taken to zero everything.
Which is also required with the gy280. Its a mirco helicopter, there isn't enough mass to really slow 3D, you'll be chucking it around with either gyro.

In my opinion the best thing you can do with a stock v120 is buy it, fly and fix it with stock parts.

The frame is too weak and disk too small to gain going 2s, there is only one 2s battery that fits correctly and its mah only allows a couple minutes of 3d if you don't want to ruin it.

If you are power hungry, a big 1s motor with a high tooth count pinion will wild the helicopter quickly, but then the bevel gears or main gears start failing. It gets old replacing the bevel under the main, if you go with metal gears, it gets expensive changing main gear when the transmission teeth fail.

If you enjoy upgrading and building more then flying, a gy280 is fun, although disappointing for the expense. The v120 foundation isn't worth the effort, sell it and buy a used MH rotary framed 130x, that frame is a good match for the gy280 with a foundation you'll be happy with once you've invested too much.

But if you bought a micro heli to learn on or fly without a care if you crash, just leave it stock. The v120d02s v2 is the opposite of the 130x, its best just as Walkera made it.

just a micro opinion

[sco88]

Originally Posted by BHChieftain

I have heard the devo7 is very cryptic on how to set... I don't have that radio... maybe somebody else can pipe in on that one!

Chief

Don't think the problem is the radio, -12% is just the max offset you can get on the throttle with the trim switch. After a bit of googling it seems that the receiver has a bug where 0% throttle still causes the blades to turn, there are two possible fixes;

A receiver firmware update - this update came out a while ago so I'm surprised mine hasn't got this already but maybe it's old stock.
Use the radio travel adjust to offset the throttle with a bigger negative range - I've done this and now the blades don't turn with stick pulled right back in Normal mode.

I've made two mods already - the standard battery plug is junk so I've upgraded to micro deans and after checking the CoG it seemed a bit tail heavy so I've made a new lightweight tail skid.

The rudder control seems quite slow and lazy - I've the got throttle % dialled back at the moment to about 50% in hover so maybe the headspeed is too low, other than upping the throttle what else can I do to improve the rudder response - there's not a gain pot on the receiver for rudder so is it all about radio settings?

Cheers,

Simon.