best practice rudder and gyro limit setup (EXI-450-SE)

Post Reply
jbeebo
Posts: 107
Joined: Mon Nov 05, 2012 6:31 pm
Country: -
Location: Los Angeles burbs, CA

best practice rudder and gyro limit setup (EXI-450-SE)

Post by jbeebo »

I searched the forum but couldn't find this specific topic. I did find all kinds of useful other stuff though :) Sorry for long post I'm trying to be clear and detailed.

When setting up the rudder servo and gyro limits on a heli, it seems there are multiple means to the same end. I'm new to helis so wanted to run this by the more experienced folks here and make sure I'm not missing something...

Here's the different way's I've tried to setup travel limits of the SG-90 analog rudder servo when run thru a GY48V gyro on an EXI-450-SE heli. Radio is running open9x-r1761. First, I did the following:
1) set the ball 8mm on the servo arm. This is the recommended distance and seems to give +/-45deg of servo travel, which will make for good resolution for the gyro.
2) servo arm 90deg to body when +/-100% limits and 0% subtrim, 0% trim.
3) moved servo on boom to center of tail travel

Now, the model is mechanically setup and centered, so off to set the travel limits! Here's where I see 3 different ways to set the travel extents, and I'm not sure which is best. For each option below, I'm giving numbers for rudder channel "weight" on mixer pg6/11, then plus/minus limits on limits pg7/11, then limit dial setting of GY48V (from 60 to 140). An example:
[tab=30]100, -52, 24, 140 translates to:
[tab=30]rudder channel weight 100% on mixer pg6/11
[tab=30]rudder channel limits -52% to 24% on limits pg7/11
[tab=30]GY48V limit pot set at "140"
option A) use rudder channel limits to define max travel. Settings = 100, -46, 43, 140. This works well and gives full stick travel for full rudder travel.
option B) use rudder channel weight to define max travel. Settings = 43, -100, 100, 140. This works well and gives full stick travel for full rudder travel.
option C) use limit pot on GY48V to define max travel. Settings = 100, -100, 100, ~110. This works, but not well IMHO. At a little more than +/-40% of rudder stick movement, the rudder is at full travel and the gyro clips the radio signal, effectively ignoring the signal for >|40%|

Questions/concerns:
1/ if I use option A or B above, can the gyro overdrive the servo? I tried it and it seems like no in Rate and HH mode.
2/ if I use option C, I discovered I can regain Tx rudder stick resolution by lowering rudder channel weight. Settings = 43, -100, 100, ~110. Is this the correct way?
3/ because I can achieve the same end, overall which is the better way to limit travel?
4/ to hover in rate mode without requiring to hold the rudder, I need ~+15% subtrim. Should I leave the subtrim in there (and leave limits @ -100, 100) or mechanically shift the servo on the boom, then set subtrim and limits to 0, -100, ~85?
5/ for HH mode, rudder trim is mostly irrelevant right? But as I understand it's best to get the bird flying well in rate mode, then switch to HH mode and adjust gain - then you're done.

TIA for any advice, suggestions or wisdom offered.

User avatar
kaos
Posts: 3247
Joined: Wed Dec 28, 2011 1:15 am
Country: United States

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by kaos »

'limit' on tail servo does not limit the servo movement. It changes the piro rate. If you are new to heli, on your first set up don't change it, set it at 100 unless it is too fast when you move your rudder stick.

To limit the tail servo movement you need to use Gy48V 'limit' pot to do it. But gy48V sometimes won't do a good job, you may still have some binding with extreme right rudder. but it won't matter, in real fly you rarely do extreme right rudder any way except full piro punch up. I always set my limit pot on gy48v at 0 and it still binds on extreme right rudder.

ON gy48V (or any gy401 clone), you set up your heli at rate mode with a gain of around 40-50% by moving the tail servo back and forth till it hold, for finer adjustment adjust the linkage rod length by half turn or full turn of the ball link holder. for the finest adjustment, use the subtrim (you should only do a few clicks at most). Once your tail holds at rate mode at 40-50% gain. You MUST adjust your tail to hold at rate mode without drift or the tail will never hold right. This is the most important part of tail set up. Then switch to HH mode, it should hold. raise your HH gain as high as you can without a tail wag. You are done with tail set up.
jbeebo
Posts: 107
Joined: Mon Nov 05, 2012 6:31 pm
Country: -
Location: Los Angeles burbs, CA

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by jbeebo »

Thank kaos for the advice, it is much appreciated.
I slept on it last night and came to same basic conclusion so was glad I wasn't thinking crazy.

to reiterate seems I take the following steps.
-right now the tail servo arm is centered and the tail slider is also centered in travel. But when I did test hovers I needed a bunch of right rudder stick to keep the nose forward (in rate mode). Thus, I could fix 2 ways: subtrim or correct it mechanically on the bird. Sounds like mechanically is the way to go. Make gross adjustments by sliding the servo and fine adjustments with the linkage rod, aim to get subtrim near zero. Goal is no tail drift at center stick - cool.

-after that's done, the distance from servo center to bottom out of the tail slider will be shorter one direction than the other. While giving full stick on the TX, set the gyro limit pot to get full travel when tail slider is right. Now the gyro will not overdrive the tail mechanism no matter the gyro or radio commands. For this particular bird/servo/gyro the gyro limit pot would ~110 (in the range of 60 to 140 per sticker on gyro).

-make small adjustments to subtrim if necessary.

-At this point however, about half of rudder stick travel will cause full motion of servo, so I need to adjust either rudder channel "weight" in mixes page or the plus/minus limits on the limits page, which adjusts the ratio of rudder stick (input to mixer/limiter in open9x) vs. rudder command (output of TX). Then I'll have full stick travel equate to full servo travel.
[tab=30]Q: which is better; weight adjustment or limit adjustment? I'm leaning towards limits, and leave weight at 100%.

OK! bird is ready for more test hovers and gyro PID gain settings...
-because analog servo, DS switch off, set servo delay pot=0, rate mode, rate gain ~35% as a start. In mixes, I have GEA switch set so 0=rate mode (0% to -100% gain signal) and 1=HH mode (0% to +100% gain signal). Gain is adjusted by P3. Adjust rate mode gain so tail doesn't wag around. Permanently set this gain in 9X by forcing that value when !GEA. I've already played with rate mode gain and approx -33% seemed to work well.

-now switch to HH mode. Adjust gain so tail doesn't wag in steady hover. Do a bunch of piros and check for tail bounce-back or mushy response. Adjust delay pot on gyro until tail comes to abrupt stop with no overshoot or mush on piro stop. This is a cheapy analog servo so some gyro delay will likely be needed.

DONE!

Do I have the sequence right?
User avatar
Kilrah
Posts: 11108
Joined: Sat Feb 18, 2012 6:56 pm
Country: Switzerland

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by Kilrah »

Sounds good! Just this:
jbeebo wrote:-At this point however, about half of rudder stick travel will cause full motion of servo, so I need to adjust either rudder channel "weight" in mixes page or the plus/minus limits on the limits page, which adjusts the ratio of rudder stick (input to mixer/limiter in open9x) vs. rudder command (output of TX). Then I'll have full stick travel equate to full servo travel.
In rate mode, yes. However, once you switch to HH mode AFAIK the gyro will expect full stick travel (the stick isn't controlling the servo anymore, it's just telling the gyro how fast you want IT to turn the heli).
jbeebo
Posts: 107
Joined: Mon Nov 05, 2012 6:31 pm
Country: -
Location: Los Angeles burbs, CA

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by jbeebo »

Interesting...will have to experiment with that later. If that's the case, then perhaps I should set a mix such that rudder output:
-during !GEA (rate mode), rudder signal is adjusted by weight and gain signal to a fixed -33%
-during GEA (HH mode), then weight is 100% and gain is TBD. Might need to leave P3 as gain adjust for HH mode because of known drift/temperature issues with this gyro, but tone down adjustment range and offset to make it a fine tune knob vs. a gross gain adjustment.

Love that we can do that level of customization with Open9x!

User avatar
Kilrah
Posts: 11108
Joined: Sat Feb 18, 2012 6:56 pm
Country: Switzerland

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by Kilrah »

Yep something like this. Or use a 3-point curve instead of messing around with weight and offset, that way you can precisely adjust both sides easily.
jbeebo
Posts: 107
Joined: Mon Nov 05, 2012 6:31 pm
Country: -
Location: Los Angeles burbs, CA

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by jbeebo »

hmm, you mean create a curve for P3 which adjusts range of gain adjustment and reference the curve in mix page vs. adjusting the gain range by changing weight and offset of P3 directly in mixes?
User avatar
Kilrah
Posts: 11108
Joined: Sat Feb 18, 2012 6:56 pm
Country: Switzerland

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by Kilrah »

No, I meant for the rudder channel.
One mix active when !GEA, 100% with a 3-point curve adjusted to have full stick travel on both sides in rate mode, and another mix active when GEA, 100% with no curve for HH mode.
jbeebo
Posts: 107
Joined: Mon Nov 05, 2012 6:31 pm
Country: -
Location: Los Angeles burbs, CA

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by jbeebo »

Got it, thanks for clarifying. Seems like a 3point curve can do exact same as weight + subtrim + limits all in one neat, easy to comprehend package.
User avatar
kaos
Posts: 3247
Joined: Wed Dec 28, 2011 1:15 am
Country: United States

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by kaos »

It is normal for the slider to be on one side for gy48v. Nowadays I just start the setup with slider at 1/3 to the boom side. I don't fly in rate mode. Always HH.
I set my GEA with rate and !GEA with HH. the GEA is just for set up and it is back to !GEA/HH every time I fly/turn on the Tx.
I also used P3 to adjust the gain. After initial set up put the setting in and leave the P3 to 0 every time at start up just use it for minor gain adjustment as needed during fly.

here is one of heli ch5 /gyro ch:
79% HALF !GEA
40% HALF GEA
+30% P3

that 30% gives me much finer gain adjustment during fly.

I don't use any curves and weight is always 100%. Just make sure you got your rate mode tail set perfectly by adjusting the tail servo/linkage rod position without any drift.

Here is my EXI SE V2 with gy48V and a DS919(or MD 922 , can't remember now) servo. (don't have much luck with analog servo on the tail) ;)
This particular heli is still on stock T9X.
http://www.youtube.com/watch?v=eYhp4INf62U
jbeebo
Posts: 107
Joined: Mon Nov 05, 2012 6:31 pm
Country: -
Location: Los Angeles burbs, CA

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by jbeebo »

Thanks kaos and kilrah for feedback. Today I setup bird as suggested and things went pretty well. I managed to get the servo position set such that little to no rudder correction was required even in rate mode. Adjusting the gyro limit pot worked champ and bird flew well. Found 30% expo was too much as I didn't like the lack of perceived authority near center followed by rapid change at extents - will tone it down a little. Didn't get to HH mode gain settings as wind picked up and was sketchy to fly in the tight space I had in backyard...

I noticed the gyro hunts around a bit in rate mode even with low gains and some delay, and discovered some slop/lash in the rear tail slider mechanism, maybe that's the cause? Also I'm running a cheap a$$ analog servo for the tail, which no doubt makes the gyro's job harder - might upgrade to a digital heli specific tail servo. I'm the 3rd owner of this trainer heli so it's seen some days, so to speak.

Can I run digital tail servo and keep analogs on cyclic?
User avatar
Kilrah
Posts: 11108
Joined: Sat Feb 18, 2012 6:56 pm
Country: Switzerland

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by Kilrah »

jbeebo wrote:I noticed the gyro hunts around a bit in rate mode even with low gains and some delay, and discovered some slop/lash in the rear tail slider mechanism, maybe that's the cause?
Very likely, yes. Slop is baaad.
jbeebo wrote:Can I run digital tail servo and keep analogs on cyclic?
Yep of course. Was a common setup at the beginning of digital servos, where you could afford a good one to work on the tail (you can even find matched gyro/servo pairs in high end stuff), but adding 3 more digitals on the head was just too expensive.
User avatar
kaos
Posts: 3247
Joined: Wed Dec 28, 2011 1:15 am
Country: United States

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by kaos »

Kilrah wrote:
jbeebo wrote:Can I run digital tail servo and keep analogs on cyclic?
Yep of course. Was a common setup at the beginning of digital servos, where you could afford a good one to work on the tail (you can even find matched gyro/servo pairs in high end stuff), but adding 3 more digitals on the head was just too expensive.
HUmm, too expensive?
try corona DS939 (8.00 each from HK) DS919 for tail is only 9.00 both digital metal gear. I am cheap (that is why I got into T9x and er9x :lol: ).
Never used a servo > 20.00 :mrgreen: on the heli cyclic, metal gear is almost a must or you are looking at stripped gear every time you have a minor crash. But analog servo for cyclic is just fine (like cheap Tpro-90, not the Tpro-90s) Only thing about these servos is DS919 you want to run it on 6V ot hold tail better. and both corona servo flanges is weak, fill the cavity under the flanges with epoxy and using washer or servo mounting plate or you can smash the flanges just by overtightening the mounting screw a bit. 5 of my 7 450s are running these cheap analog /digital metal gear servos. I even use HXT900 (3.00 @) for cyclic. HXT 900 is very precise but plastic gear. You can replace the gear for .50.
A relatively cheap but excellent tail servo is EMax 9258 (around 19.00), digital metal gear but you need an adaptor plate or correct bracket to mount on the SE tail boom. It has two mounting holes each flange. It is equivalent to a DS520 by Align.
User avatar
gohsthb
Posts: 1412
Joined: Wed Dec 28, 2011 2:32 pm
Country: -
Location: Naperville, IL

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by gohsthb »

Kilrah was referring to long ago . . . before hobbyking, when digital servos were the new magic.
-Gohst
jbeebo
Posts: 107
Joined: Mon Nov 05, 2012 6:31 pm
Country: -
Location: Los Angeles burbs, CA

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by jbeebo »

Excellent advice. I'm cheap and pretty handy too - hence here we are at the 9x forums!

I'm seriously considering this G401B + S9257 combo for $25 to improve tail stability. It has very positive reviews on RCgroups forums, gyro has supposedly less drift, wags and blow outs than GY48V. But yes, the servo is a little larger so might need longer servo clamps for the boom. Today the tail servo is Tpro SG90.
For cyclic I have 2x Tpro SG90, with an HXT900 thrown in for good measure on aileron! - this is indeed a cobbled up heli :lol: I'm not going for cyclic upgrades (yet), the cyclic limitation is not the machine, but rather the operator...if/when I like the looks of the DS939.

Because of slop in tail, was looking at this upgraded CNC tailbox. It replaces the single ball + fork control arm with dual ball control arm. The ball/fork control arm and mating pin in tail slider is the major contributor of the lash, they are just plain worn out plastic bits. My only concern about that tailbox assy is compatibility with my EXI-450-SE-V2. It seems EXI tail boom OD is standard 12.0mm dia x 347mm length.
User avatar
kaos
Posts: 3247
Joined: Wed Dec 28, 2011 1:15 am
Country: United States

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by kaos »

gohsthb wrote:Kilrah was referring to long ago . . . before hobbyking, when digital servos were the new magic.
-Gohst
Gee, I did not realize Kilrah is that old. :lol:
He must have some young guy disguise as him in one of his video. :mrgreen:

Jbeebo:
I don't know about that ebay combo, no experience with it. I don't think it is the genuine Futaba s9257. that alone will be more than 50.00.
Futaba s9257 is an excellent tail servo but the clone may not be. if rcgroup is reviewing the same ebay combo and have good result then go for it. that gyro is also a Gy401 clone, the Futaba gy401 has been gold standard tail gyro for a long time. but not all the clones work the same. gy48v is one of the clones. if you have vibe in your heli , your tail will be gone. vibe is the no.1 killer for gyro. use a good pad and if needed put some hot glue in the gyro pcb to fix it in the case will solve the problem. I have 5 450 running on gy48v and one running on HK401B without tail problem. use this pad, better than the expensive gyro pad sold on the market , at least equivalent to those expensive ones.
http://www.hobbyking.com/hobbyking/stor ... oduct=8999
one sheet for < 3.00 last for ever, sticky as hell , I used it every where I can use a 5 mm thick double sided tape.

The Emax also is a 9257 clone of Futaba s9257 which I have heard done a really good job. the 9258 is just the metal gear version of that. Have one Emax 9258 in my box but none of my tail servo breaks yet, so I have not really used it.
One thing I leraned from heli it needs much more torque than the similar size plane. Not a good idea to have different type of servo for cyclics. Try use the same kind of cyclic for all 3.

One word of advice, upgrading your plastic EXI may not be the best way in the long run. It may cost more than just get a full metal head and tail with CF body heli kit, like HK 450pro. the plastic head and tail can cause problem easily such as vib and slop. A HK 450 pro CF metal kit is around 50ish. Do the math a little. been through that route too. ;)
jbeebo
Posts: 107
Joined: Mon Nov 05, 2012 6:31 pm
Country: -
Location: Los Angeles burbs, CA

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by jbeebo »

Decisions, decisions...
Amazing you can buy a whole HK450GT kit for $60 shipped to my door. No doubt this bird will fly well. Alternately I can put about the same amount of $$ into this existing EXI to make equivalent or perhaps a little more durable. Funny how wear on 2 itty bitty plastic parts can cause such trouble and cash expenditure.

Regardless of which path, a digital tail servo is an excellent idea. I could use the GY48V and just get a S9257 clone for $15 and save ~ $10 vs. the combo kit.

Indeed mixed bag of cyclic servos is by no means optimum. I could put the HXT900 from AIL onto RUD and take that SG90 from RUD up to AIL to match rest of SG90 on cyclic...

I guess it boils down to this: put minimum $$ into this bird and keep flying / learning, even if the heli doesn't perform top notch (e.g. live with some tail wag), or start that inexorable upgrade path either thru a whole new kit or bits and pieces.

I really appreciate the advice from you more experienced whirly-birders! I think I need to sleep on it - that works well for me :)
User avatar
kaos
Posts: 3247
Joined: Wed Dec 28, 2011 1:15 am
Country: United States

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by kaos »

"perhaps a little more durable" ??

NO such thing as durable heli. you crash, they break, metal or plastic. ;) you replace parts (if you can trouble shoot which one(s) out of 50 parts that is/are damaged), you can't bend or glue it back together most of the time. It's a money pit for parts. ;) I had one incidence the heli dropped from 3 ft right after take off and end up with the most expensive repair of all my heli repairs. all 3 cyclic servo broken, bent main shaft, striped main gear and tail drive gear, fly bar, main blades. What happened? I forgot to put the screw on the tail servo and it did not come loose while I was setting up the tail. It came loose the 1st time after I take it out in the field. When I got home, I saw that little screw is sitting in a small tray on my desk. :?
These 450s is powerful with 3K rpm main blade but the parts is like bird legs.
Practice a lot on sim till you can get the head in nailed at least on the sim, can save you a lot of crashes. 99% of the the crashes is pilot error which is easily done. Flying plane I can close my eye for a while if a sand got into my eye. Flying heli, if I blink it crashes. :lol:
User avatar
Kilrah
Posts: 11108
Joined: Sat Feb 18, 2012 6:56 pm
Country: Switzerland

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by Kilrah »

kaos wrote:NO such thing as durable heli. you crash, they break, metal or plastic. ;) you replace parts (if you can trouble shoot which one(s) out of 50 parts that is/are damaged), you can't bend or glue it back together most of the time.
That's exactly what drove me away from helis quite some time ago already, after crashing because the landing skid got caught in grass, leading to 2 weeks waiting for parts and nearly a day to replace them and set things up again ;)
I had one incidence the heli dropped from 3 ft right after take off and end up with the most expensive repair of all my heli repairs. all 3 cyclic servo broken, bent main shaft, striped main gear and tail drive gear, fly bar, main blades. What happened? I forgot to put the screw on the tail servo and it did not come loose while I was setting up the tail. It came loose the 1st time after I take it out in the field. When I got home, I saw that little screw is sitting in a small tray on my desk. :?
Ouch.
User avatar
kaos
Posts: 3247
Joined: Wed Dec 28, 2011 1:15 am
Country: United States

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by kaos »

Jbeebo: one last thing, HXT900 is not good for the tail. for the tail you want a fast servo 0.09 sec or faster. for cyclic you want more torque 1.6-1.8 Kg or above and spd at 0.12 would be just fine. But with cheap servo, you have to take into account of these spec are 'puffed'. for cheap tail servo I look for 0.07 sec or better. HXT900 is not fast enough. you will have some drift. I don't know how well you fly cp heli. As difficult as these heli fly, for less experienced, if you are fighting the tail drift, you can expect you will crash. for more experienced flyer they can handle some drift.

Kilrah: I think you misinterpret what SKID is (actually they mislabel it, should be 'stand'). It is only used to hold the weight of the heli. They really don't 'skid' around, especially around grass. :mrgreen:
jbeebo
Posts: 107
Joined: Mon Nov 05, 2012 6:31 pm
Country: -
Location: Los Angeles burbs, CA

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by jbeebo »

Thanks kaos, I thought the HXT900 on the tail would be no better and maybe even worse than SG90 on the tail so today I ordered the G401B + S9257 ebay combo based on RCgroups reviews. When it arrives, the SG90 from RUD will replace the HXT900 AIL, so will have 3 equally junky cyclic servos. I might run the GY48V a little while longer and see if the servo alone improves the tail hold situation.

I pulled apart the tail control arm and slider mechanism today - sloppy city. I need some new parts. Tried to find just the control arm and slider but not much luck (this for $10). So $17 for just new tail assy from ebay or $60 for new tail plus a bunch of "free" spare parts (i.e. order the HK450GT kit...)? decisions decisions.

I'm definitely a newbie heli pilot and it was definitely hard to control the bird while fighting tail drift and wag, thus my desire to get the tail setup best I can. How did people fly these things before gyros??

Love the comments about birds legs, skids, durability etc. :lol: I think anyone that wants to fly RC helis must be crazy - hey wait - that's me!!

While waiting for parts, back to the sim!
User avatar
kaos
Posts: 3247
Joined: Wed Dec 28, 2011 1:15 am
Country: United States

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by kaos »

jbeebo wrote: I think anyone that wants to fly RC helis must be crazy - hey wait - that's me!!
You are right about that. ;) For a few very gifted person can get a handle of flying it relatively quick, or you need an iron will or just by nature like to be tortured. :mrgreen:

statistically, I think i read some where only 5% of all heli 'trier' stayed in the business and continue to fly.

Good luck on your fun adventure!
User avatar
gohsthb
Posts: 1412
Joined: Wed Dec 28, 2011 2:32 pm
Country: -
Location: Naperville, IL

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by gohsthb »

I'm not sure but that 5% might be a bit high.
If it were upgrading the gyro, I would have gone with a ga250. It uses a mems sensor, which is worlds better than the piezo types. And it is only $10 at hobby king.
-Gohst

Sent from my LG-P999 using Tapatalk 2
User avatar
kaos
Posts: 3247
Joined: Wed Dec 28, 2011 1:15 am
Country: United States

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by kaos »

yep, ga250 is a good one. I have one too to be used when my gy48v fails (ordered as a weight filler for something else). But every time you are prepared to replace them, they seem to know and start to behave. :lol: so I am still using the 5 old gy48v. ;)

One thing about these piezo gyro. My understanding is piezo sensor are more sensitive to temperature change. Once I learned that, just leave the heli at the site of flying for 5-10 min before start the motor. They seem to be doing just fine. I test it in the winter. When my house is at 74 degree while in the garage in only 45 degree. I put the heli in the garage for 10-20 min then start it. They behave just fine.
jbeebo
Posts: 107
Joined: Mon Nov 05, 2012 6:31 pm
Country: -
Location: Los Angeles burbs, CA

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by jbeebo »

a quick update. Impatiently I flew the 450 in the too-small space in the back yard with old worn out parts as mentioned above. Tail was wagging all over the place. Some gusts of wind were more than my skills could handle and heli below into hanging branches of trees. bent main shaft, broken main blade, bent flybar rod, and bent tail boom (from blade strike). Lesson learned. :roll:

A few weeks later and it's back together with V3 head on a V2SE chassis, new tail assy, new boom, new digital S9257 clone servo - same GY48V gyro. But this time, before trimming rudder in-flight I made a lazy-susan type turntable out of old HDD bearing and platters. No matter how I tune/adjust that GY48V in rate or HH mode, I could not get right of crazy tail wags and general instability. I opened the GY48V case and saw wear marks of PCB against case meaning vibe was shaking the PCB around. Could do the hot-glue or silicon fix, or swap in the other GY401 clone I had, but was placing an order at HK anyways so splurged on that $10 GA250. Should be here in a week or two and can try again.

In the meantime spending more time on the Sim, which seems to be paying off. I'm burning thru fewer and fewer virtual helis now! ;) Thinking about investing in a mCPx or FBL100 or Genius CP or V120 to get more stick time in a smaller space. Supposedly I can bind them to 9X.
User avatar
kaos
Posts: 3247
Joined: Wed Dec 28, 2011 1:15 am
Country: United States

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by kaos »

don't fly in more than 3 mph wind in the beginning. You will crash easy. If you can't hover well with no wind, once the wind hits you WILL crash.
Hope you have your TG on. learn to hover only 1-3 ft high in the beginning. if some thing happens, just put it down, with TG, it won't hurt much. not like plane, it can float in the air. at 4-5 ft something goes wrong even with TG , it will break something. People say you can't get out of the balde wash at 2-3 ft, I think it is actually good to learn how to deal with wind from the beginning with that back wash. ;) I started out like that in the garage (I don't recommend it though) because of the wind issue. but I only get it up 2-3 ft, higher I will hit the ceiling, lower I will hit the floor with TG, If I slide I put it down quickly so I won't cut my walls. little by little I was able to do that pack after pack without putting the heli down and do piro in the garage before I went out to fly. It takes time. ;)
heli gyro does not like to be pinned down on the lazy Susan. You need to make that link kind of elastic I think.
try the hot glue in gy48V. (none of my gy48v has hot glue , I only have one HK401b need hot glue). did you order the gyro pad from HK at the same time? gyro pad on 450 is critical, that dampens out the vib. make sure your belt is not double twisted or too tight. do you have vid how the wag look like?
cp heli is a double edged sword. If you can't build it/tune it right, it won't fly well - for beginner that means easy crash. but before you can fly to a certain degree, it is hard to tune it right. you don't know it is your flying or its the heli not flying right. ;)
Now you are into the dark zone of cp heli. after a crash, ANY part or bearing can be damage without obvious sign when looking/examine it. some times takes days or wks to sort out one stupid bearing is the cause. did you check your main bearing after the crash, now you have a new head. use a good main shaft and roll the bearing on a flat surface, you will feel the 'gritting' if it is bad. try with a brand new good bearing so you can feel how smooth a good bearing feel like. you can't tell the damaged bearing by looking at it.
definitely working on the sim. side in and head in. if you can do side in in both direction, you will be able to fly FFF. if you can do head in some what, that is the time you don't crash often any more.;)

here is a vid I did when I built my 1st cp heli - an EXI se v2. I was struggling with a 'RTF' eRazor(RTF stands for 'Ready To f--k up in cp heli world ;) ). Once I built this one, I was in heaven. look at the TG and how low I was practicing hovering. Now I do that all the time to set up my heli because it is an ideal no wind place. ;) I am prepared to sacrifice the heli if something happens, in the garage it is very close to me. at 2-3 ft, I can put in down in a split sec. I put -2 degree on my normal pitch curve so I can put it down quickly with a chop of throttle stick.
http://www.youtube.com/watch?v=gsSv5XSV8Mg
jbeebo
Posts: 107
Joined: Mon Nov 05, 2012 6:31 pm
Country: -
Location: Los Angeles burbs, CA

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by jbeebo »

Thanks for helping this noob along kaos!

re: lazy susan, I had read that before so tried to give a lot of compliance by loosely attaching it with plenty of bubble wrap wrapped around skids. landing gear can move freely L/R/U/D about 3/4", yet heli could not get airborne. Heli spins up normally moving thru transitional vibratory modes and rudder behavior matches that when it was airborne. I think it works OK...

re: foam, absolutely I believe this was a factor. there was a small piece of 1mm thin black foam holding it down. Foam did not cover entire bottom of gyro. I ordered that foam pad you suggested. I have some 3M grey HD tape I could use too. Given I have the GA250 coming soon, I'm going to just wait for that superior MEMS gyro vs. trying to make the GY401 clones work with lotsa experiments, though might be interesting to see if I can fix it :)

Your vids of the EXI look nothing like mine. My tail w/ GY48V wags all over the place, no matter the gain, delay, analog or digital settings, etc. An example of my GY48V behavior: power up heli but before spin-up, gyro behaves as expected. Spin-up heli, tail goes crazy. Spin down heli, tail still going crazy, servo arm moving +/-20deg, even with the rotor totally stopped. Seems vibe causes it to go nuts and it doesn't recover until power off/power on again. Same thing when I hovered in air. It's clear not all GY48V do that, just mine, but I'm over it and hope the ga250 plus good foam will fix the issue.

re: setup, yes critical. When I got heli, swash totally out of alignment. First tried to align with simple tools/visually but found results not good. So I built my own leveling tool. Using it adjusted mechanically level at center, and then v. slightly adjust limits in 9X to keep it level at min/max collective. I think that alone will major improve chances of success. I'm getting good at adjusting this bird and am confident I could build one from a collection of parts. I have whole new head including new mainshaft, feathering shaft, etc. Main shaft bearings are smooth and I realigned them too. My heli runs pretty smooth as I'm careful with setup e.g. blade balance, tracking, etc. Example, it runs way smoother than my friend's fo-real Trex 500, and his tail is pretty solid, not rock solid but 100% better than mine was! If memory serves I have -2deg to +7deg collective for ID0 setup with pitch gauge.

re: sim, making headway. changed from thumb to pinch grip and found that helps for fine control of cyclic. I was a thumber in my fixed wing days so I'm retraining myself. Can hover all directions OK, keeping within ~10ft circle worst case. FFF in straight line with hammerheads or turns at either end OK. Simple funnels are sloppy but I'm working on rudder/cyclic phasing to improve. Rainbows are OK too. Inverted hover needs lotsa work! The sim is an excellent investment, and am trying to be a good student following progressive/regimented training program.

My work schedule forces me to take about 3week hiatus from helis. Mid march I should be back in air...I'll check in then.
Cheers!
User avatar
kaos
Posts: 3247
Joined: Wed Dec 28, 2011 1:15 am
Country: United States

Re: best practice rudder and gyro limit setup (EXI-450-SE)

Post by kaos »

I would suggest set your ID0 pitch as -2 to +9. +7 may be a little too little.

Glad to see you back in March, mean while take the sim with you if possible for whatever you are doing. ;)

Post Reply

Return to “Helicoptor Programming”