Virtuall flybar for AP applications?

[scary]

yeah?? well, ill be damned :)

i think a light just turned on about it aswell, i was too busy thinking about how the gyros would tell the servos how to tilt the swash (especially 2 servos getting their signals from one gyro), but its the AP2000i which takes care of that.

Cheers for your help!

[MarkWebber]

but its the AP2000i which takes care of that.


Precisely why the gyros must go ahead of the AP2000i and why the IR stabilization is not terribly effective with the gyros in HH.

[scary]

So to get the best stabilisation at a location, we should really use the IR in RR, which will locate the heli in space comparable to the horizon, and then flick over to HH and let the gyros take care of the heli stabilised in relation to keeping the swashplate level.

This seems logical to me! :)

[scary]

gday again guys

well ive almost done it! everything is wired correctly and the swashplate holds extremely well! and thats the problem... even with the gain at 0, i get oscillations 1 foot off the ground and i have to ditch it.

Ive tried taking off in rate mode but i dont like the feeling... i like to have everything central and return back to centre. So taking off in HH seems to be ok (apart from some twitching) and then its all fine for about 3 secs and then i have to bring her back to earth.

It seems as though it is very sensitive, so perhaps creating some exponential cyclic control??

Just not sure if i can do that on the JR XP8130...

..i was just thinking, im flying the Hurricane 550 and this thing is light... 1950grams... but im doing all this for AP. Would it be better to have more weight with such a setup?? maybe i should mount the camera (or add some dead weight under the heli) and see if this drops the sensitivity of the gyros?



cheers

[MarkWebber]

What gain are you using on the gyros? I had to keep my 401's between 13-15% or it would do the same. Also, if your engine tuning is off it will induce oscillations. Does it do the same if you reduce gain to 0%?

[scary]

Gday Mark

im running an electric engine so i dont think tuning is an issue. However, running the gyro's at 0 gain also brings in oscillations...

[scary]

Gday Mark

im running an electric engine so i dont think tuning is an issue. However, running the gyro's at 0 gain also brings in oscillations...

here are some pics of the setup

http://img.photobucket.com/albums/v190/skary/heli/IMG_0170resized.jpg
http://img.photobucket.com/albums/v190/skary/heli/IMG_0173resized.jpg
http://img.photobucket.com/albums/v190/skary/heli/IMG_0174resized.jpg

[scary]

thinking about my flight this morning...

i did realise that trying to start off in rate mode was not doing what I anticipated. When in rate mode, the swash would tilt to the left constantly, and i had to hit HH to level the swash again. Shouldnt rate mode just move to a state inputted by the sticks? and not move itself like in HH?

[MarkWebber]

Any trim or subtrim on that channel? How much pitch on the cyclic? You might want to try a bit of expo on the cyclic to reduce sensitivity around center. My hands shake a bit as it is and that would be readily seen in the heli before I added expo.

No loose linkage in the heli, right? That could cause a bit of oscillation, as well. I would look there as the gyros are just along for the ride when at 0%.

[scary]

Thankyou Mark

I will check for loose linkages but I dont think this would be the case, as it is a very new heli which comes almost ready to fly.

Is there anything on the AP2000i which can create this exponential input?

[MarkWebber]

Nothing in the AP2000i. This is in your tx.

Also, if you could take another pic from the swashplate up. It wasn't too visible in the others.

[scary]

im still thinking about this and questions keep coming!!

Exponential of the cyclic in the TX couldnt mean the gyro's are influenced to react exponentially because they just react relative to their orientation?? so that cant help...

Would there be any difference that I am trying to fly the heli with the flybar still attached?? making the gyros far too sensitive?

Would adding some dead weight make the heli less nimble in the air? Resulting in the gyro sensitivity to be reduced??

[MarkWebber]

I didn't realize that the flybar was still attached. I'm not sure what effect that would have.

The expo suggestion was for the possibility that it's from small, unintentional stick inputs.

[scary]

well im getting very discouraged :(

I have removed the flybar and tried to give it a flight this morning. After removing the flybar, it seemed to get rid of the oscillations, but the heli is still very responsive.... really responsive.
After trying to take off in HH, I found the stick input to be extremely sensitive. Also I couldnt understand why the heli wasnt levelling itself. THe gyro gains is around 7%, maybe a little high? So i gave it 25% expo on the cyclic. This didnt really help - i got about a foot off the ground and became paranoid, gave it too much cyclic and it came down with a boom strike :( the strike also sent my FMA copilot flying in a couple of pieces.
I found flying with the flybar more stable and fun.... this isnt enjoyable at the moment....

Because i want this for AP, i have manufactured a front mount with just some dead weight for now, and i had the batteries at the rear of the heli for counter balance. With the additional weight, it would only take off with full headspeed and about 10° of pitch which i found dissapointing also.

Well, i guess ill get a new tail boom, some blades and try again!

[MarkWebber]

How much pitch do you have on the cyclic? I had to add >40% expo to slow down the cyclic on mine.
Also, a bit of delay on the gyro was required if I remember correctly.

[scary]

wow, 40%!
okay, that makes me feel a bit better. I thought i was the only one having these oversensitivity issues. Also, ill start off with the gain at 0% and bring in a delay.

Thanks Mark, after I've slept on it, im rather happy that all i need replacing is a tail boom ($5) and the tail rudder line ($2.50)

My pitch must be around 10° but i think i might also increase that as high as possible due to the increased weight im carrying.

Cheers

[MarkWebber]

I'm refering to cyclic pitch, not collective. If you've got a lot of cyclic pitch, that will make it even more sensative. Due to the removal of the flybar's gyroscopic effect, it's going to be more sensative to stick inputs. Cyclic will be instantly applied to the blades rather than mixed in by the flybar.

[MarkWebber]

What are your rates for Ail and Ele in the AP2000i?

[scary]

Gday Mark

Sorry for the long break between posts; I have just recieved all my replacement parts for the Hurricane to get it going again.

I dont have my gear in front of me but i dont believe i have set any rates in the AP2000i.
Should I have set anything?

My next approach is to dramatically reduce the sensitivity of the cyclic by programming a really low linear input, with maybe 40% the maximum value.

[MarkWebber]

Been thinking about it a bit. I should have said rates in the tx. This is because the gyro 'piro' rate is dependant upon the rate from your tx. If you're at a higher rate setting, the gyro is going to respond more quickly. Try reducing the rates to slow the gyro down.

[aramsdell]

Scary, great choice. XPS system. Got it and the AP2000i on my helicam.