Virtuall flybar for AP applications?

[MarkWebber]

Mark

I was hoping that I'd get a chance to try out the mechanical reduction today. Won't quit raining, though. I feel good about it. After making the change yesterday, motion test yielded much more subtle gyro inputs. I think that will turn out to be the answer. I wish I'd have made that change prior to gyro adjustments. I'm sure I'll need to reset the gyros now. :roll:

If the weather will just improve now then I can get to dialing this in. I'm itching to fly it with the IR installed. Should be sweet!

[Angelos]

Mark (oscillator),
It is recommended that you use Normal (rate mode) gyros. In which case it does not matter which gyro you decide to use the rate mode does not suffer from drift. However, because the cyclic signals pass through the gyro I recommend that you get decent quality gyros. Some of the cheap gyros have very low resolution and you may loose the nice “feel” of the cyclic. The 401s that Mark Webber picked are probably a good choice. Let’s wait and see how get gets on.

-Angelos

[MarkWebber]

Got to get in another test flight today. A bit windy and only 25F but I couldn't help myself.

It's much better having moved the ail and ele servo links to the inner servo arm hole. No oscillations at all. I'm thinking it might even be able to stand a bit more gain and less delay. It was a bit pitchy in fff. Gain on ele gyro, probably?

Anyhow, it's back to flying more like preconversion R50. Except the roll/flip rates are ridiculious. There does seem to be some roll/pitch coupling. Maybe rotor phasing needs tweeking. Hard to say because I was shaking from the cold.

I need a nice day and little assistance to get it dialed in right. Even so, it's still flying pretty well. :D

[GGoodrum]

25F?? Man, you're dedicated! :D I won't even go out to the car if dips down to the low 50s... :D:D

[MarkWebber]

I hear ya, Gary. I was born in Anaheim and lived on SoCal for most of my childhood. I suppose one gets used to it :roll:

[oscillator]

Thanks for the update Mark. I was wondering earlier today if you had made any progress. Thanks for braving the cold for the cause!

Are you using the digital setting on your 401's? Would it make any difference in this application? I was considering purchasing 240's for my conversion but then remembered the 401 supports the higher rate.

[rroback]

Digital setting is really only for use when using tail specific digitals, like the 9254's. I'd go non d.s. for any other servo.

[MarkWebber]

Like Rhett said, digital's only for digital servos.

And, a faster response isn't going to be a good thing on your cyclic. All of my adjustments so far have been aimed at slowing the response of the gyros down to a managable level. Keep in mind that they will be directly aiding in cyclic input. On your tail, they don't have so much rotor disk surface to work with. Now put it on your cyclic and they'll get the heli oscillating in a big way. Like the twitch you'd get cranking your tail gain way up only the whole thing gets twitchy.

I've never used the 240's but I don't see why you couldn't. From what I've read they work well for guys that don't need remote gain. I do wonder how touchy the pot adjustments would be compared to being able to set the exact gain on a tx.

[MarkWebber]

Snuck in a flight before the storm arrives. wind 0-5mph, 20F.

I've bumped the gain from 10 to 15 and dropped the delay from 75 to 50. I'd say it's flying just about like it was with the flybar. Except for the incredible cyclic response, that is :D . There might be some tweaking left in the gyros, especially with a better pilot flying it. I haven't messed with the rotor phasing yet because it's difficult to tell if it's me or the phasing :roll: . I'd say it's pretty well set for now. I going to put the IR sensor on and see how it performs with stabilization. Sure could use some of that warm weather to come back. Not looking good for around here, though. :roll:

[Angelos]

Mark, you can get the phasing adjusted fairly well on the ground. The method is described in the AP-2000i user guide. Of course always check that it behaves correctly once you spool up and before you take it in the air.

4. Place any blade parallel over the tail boom and apply a large fore and
aft cyclic input while observing the blade for pitch changes. Adjust the
“Phas” menu screen until you find the number that result to no pitch
change on this blade. Keep in mind that the adjustment range is +/-90
degrees and the value you need may be negative.

-Angelos

[MarkWebber]

Thanks, Angelos. With the blades positioned as indicated I have no interaction. That's why I'm not so sure it isn't me imputing the interaction :roll: . Hopefully, weather and skilled pilot permitting, I will be able to get this all dialed in soon. As far as I'm concerned, it's ready to have the IR feature going. It's flying just fine for my skill level.

The other thing I noticed is the tail belt is loose. Maybe it was twitching while I was rolling and flipping and made it seem as if the phasing is off. Keep in mind that this modification is following a pretty ugly dumb thumb crash.

No matter what, I'm feeling good about this conversion. I have a spare head that I thought I might use to return to flybar flight. Why? I think if I drop the cyclic pitch back to 4 or 5 degrees that it will be more tame and better for my purposes.

[oscillator]

FedEx delivered the V-bar parts for my Logo 10 today and I installed them tonight. Wow, it sure looks nice not having a flybar!

Now I just need 2 more gyros and my AP2000i.

Hey Mark - do you still expect the units to ship by the end of the month? Any more updates from your testing?

Cheers!

[MarkWebber]

Mark

No more flights yet. I've got the IR sensor on and programmed. Now I'm just waiting for better weather. Unfortunately, it's not looking good around here. Arctic Clipper on it's way. If I can get a window with reasonable winds, I'll give it a shot. Considering that it's flying pretty much like before conversion, I don't really expect the IR to do anything but perform great.

Still waiting on the cables from Spartan. Should be getting to them any time now. I am still hoping well get everything out by the end of the month.

[MarkWebber]

Finally got in a flight with the completed install. IR worked well despite horrible IR conditions. Heavy snow cover, heavy overcast and snow falling. 70% gain felt comparable to my normal 30%. My R50 behaved as it should. I just need more power to pull off the sick roll rate without bogging the head too much. :D

[GGoodrum]

... I just need more power to pull off the sick roll rate without bogging the head too much. :D

One word: ELECTRIC! :mrgreen: :mrgreen:

[MarkWebber]

Geez Gary..what's with you and this electric obcession :wink: Won't be much longer, I shoud think.

[oscillator]

Thanks for the update Mark. A few questions:

1. How are people handling the IR gain adjustment on radios that don't have a slider? I have switches out the wazoo on my DX7, but no proportional control on the extra channels.

2. Where did you end up for gain/delay on your roll and pitch gyros?

3. Are you still seeing roll/pitch interaction? If not, what adjustments did you make?

4. When do you expect the AP2000i's to ship? (you knew that one was coming ;-)

Cheers,
Mark

[MarkWebber]

1 So far, they're using a 3 position switch assigned 0, 30 and 60%, for instance. You'll need to try adjusting the gain settings to your likings. Even with a slider, I normally don't exceed 30% or so. That's just what works for me.

2 I'm not sure I'm satisfied with the gyro settings just yet. I'm at 10% gain and 35% delay. I need a really nice day or two to play with the settings to see if any improvement can be found. Still, it is flying rather well at those settings.

3 Being that I'm not the greatest pilot, I'm not convinced that it isn't me inducing the interaction. Two sets of eyes and a better pilot will tell the tale. Should I determine that there is an interaction, it should be a simple matter of adjusting the phasing in the AP2000i just a bit. Far easier than moving the swashplate driver accurately.

4 Yes, I knew it was coming and I understand completely. The cables made it to Angelos' hands and my order went out this week. Normally it takes 1 to 1 1/2 weeks to get to me.

[Angelos]

Finally the weather was good enough to do some further tests on the gyro. Here is a short video. Best to right click and select the save option.

http://www.spartan-rc.com/pub/rr_posts/ds760_4Feb07.wmv

-Angelos

[GGoodrum]

Wow, that held really well, even with that poor Raptor being on fire, and all... :D:D

[oscillator]

My AP2000i showed up on Saturday! Went to the local hobby shop and picked up 2 GY240's. So far I've mounted everything on the heli, but still in the process of setting it up. Hopefully I'll get in a test flight this weekend.

[MarkWebber]

Definately start lower on the gain and work up from there. I started too high and the oscillations were a bit unnerving. I think I was upwards of 25% and 0 delay. I've settled about 25% delay and 14% gain. Toward the end of the flight I start seeing some oscillations but I think that's just pilot input from the cold :roll:

Looking forward to your results.

[oscillator]

Something I didn't realize at the time I - the GY240 doesn't have a delay control. Hope this doesn't become a problem.

I wired everything up last night and got it working on the bench. At about 25% gain I can barely see the gyros moving the swash. At about 50% the operation is obvious. Guess I'll start with the low gain and cheap blades and hope I can hover it.

According to Mikado the control arms on my servos should be 19mm - with the flybar. They don't say anything about control arm lengths without the flybar, but I have reduced this to 13.5mm to account for the mechanical reduction that was present with the flybar. However, I now only get +-7 deg pitch with full collective travel and 100% servo travel on both the TX and the AP2000i. Do you think +-7 deg of pitch is sufficient for AP applications or should I try to get 10 deg?

[MarkWebber]

I guess that'll depend somewhat on your rigs weight too. Maybe give it a shot at the 7 degrees and adjust as necessary. It shouldn't hurt to loose a bit off the negative side if you need more positive.

From what I've experienced now, you can hover easily with low gain settings. It's in ff or windy conditions that the gyros will really be doing their thing to reduce pitchyness. Better to start low and work up than the other way round. Even when it was oscillation badly, I was still able to land safely. Then change my shorts :oops: ...j/k

[oscillator]

1st Hover!


Just spooled it up and hovered it for the 1st time a few min ago - in my garage! OK, so it was only an inch off the ground, and I had my workbench chair between me and the heli, and there are large bundles of wire hanging out everywhere, but hey, it got off the ground.

Hopefully I will get some time tomorrow afternoon to take it out and hover it for real. Once I'm happy with everything I'll start cleaning up wires and mount the IR sensor. Then it is the stretch, camera mount, down link, etc. Lots of work left.

But hey - it is looking promising!