Replies to This Discussion

Permalink Reply by James on June 22, 2012 at 2:16am

in my case, i still worry about alt hold in v2.6 but i seem to be in the minority, im going to try adjusting my throttle range this weekend and see if that improves it.

perhaps instead of tuning down the P term in RATE YAW you could increase the P term in STAB YAW, or maybe try adding some RATE YAW I to limit the overshoot.  the thing to have in mind is that there are two controllers working here, the "outer" STAB controller sets the desired heading, and the "inner" RATE controller tries to reach that heading.  its complex and different configurations have their own problems.

as i said, Dave has a tri that flies nicely (dont know how well the yaw works?) and Robert is working on improving the yaw controller for all platforms - i think this deserves a thread all to itself.

james

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Permalink Reply by Bruce Jones on June 22, 2012 at 2:36am

I'm more than happy to move this to another thread if that'd be best.

I'm using the param files Dean Wynton posted here.  I've got to say, most of the time I like how it flies - except for the yaw problem.

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Permalink Reply by Dave C on June 22, 2012 at 4:25am

Bah! Been called  into work, I'll test Rob's patch and do some tuning tomorrow :)

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Permalink Reply by Glenn M on June 22, 2012 at 1:40am

I haven't used the non-carbon gemfan props, but the carbon reinforced ones at least didn't have an insert that fit the nx4008 prop adapters well, so that's probably where the imbalance comes from. I've found the props themselves to be very well balanced, but they need to be centred well otherwise they'll be all over the place. I found the nx4008 prop adapters to be made of quite soft aluminium and I broke them, so replaced them with 3mm propsavers from rctimer and they are all good now.

I've just built a new tri today. I managed to get hold of some delrin sheet, and just cut my own frame with a dremel. It looks a bit nicer than the plywood!

What size batteries are you using? I'm running 5000mah 4s but it brings the total weight to about 1500g with gopro and security camera which is a little heavy I think. I get about a 22 min hover with apc 10x4.7s on nx4008s.

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Permalink Reply by Bruce Jones on June 22, 2012 at 1:49am

Yeah, the Gemfans were a bit tricky to fit.  I have a small round reaming file and I just took a small amount off the inside of their tightest insert.  They fit VERY tightly.

I replaced all my prop adapters too.  I think I broke 3 the first 3 times I went out flying with them.  I like the motors, the adapters that come with them suck.

I'm using 4S 3300mah batteries and getting about 18 minutes with an 80% discharge using APC 9x4.7, about 17:30 with the Gemfans.  Though that Gemfan number was flown with 5mph winds and the APC were in dead calm.

I should try some 10 inchers.

I've rebuilt this FPVMANUALS frame 4 times now.  I like the looks of it and how it performs in the air.  And in easy crashes I love how the arms just fold back and absorb the impact.  But in crashes with any speed, it seems like something always breaks that I need to buy from Tim.  I should figure out how to make the replacement parts myself.

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Wiki NinjaPermalink Reply by Gary McCray on June 22, 2012 at 1:34pm

I'm using 11x4.7 Carbon GemFans and have found them excellently balanced out of the box.

Their adapter bushings are a little tricky though, requiring careful removal of the connecting sprues and filing, sanding or reaming a slight chamfer to the edge where you insert them into the prop because they tend to grab and gall on the sharp carbon propellers bushing well edge.

I am running a KK X525 quad with an APM2 and I can tell you the GemFans are superior in every way to the stock GWS 9" 3 blade prop that comes with them. Less power consumption, higher performance and much quieter.

Your little camera is a very good lesson in RF interference to the GPS being a really good thing to avoid.

Occasionally I have though my quad might have had similar aspirations.

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Permalink Reply by Glenn M on June 22, 2012 at 1:55am

I couldn't get it to stop vibrating no matter how hard I tried with the 10mm arms. The new frame is drilled for 12mm arms, and it has made a huge difference for me in the quality of the video and stability that I'm getting out of it. Everything was balanced right before, I think the arms just flexed a little too much and they were only 40cm long or so.

I'll have to link some pics of how my new one is put together soon. It should be very easy to replace pretty much anything on it while out and about.

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Permalink Reply by Bruce Jones on June 22, 2012 at 2:09am

A good friend of mine built a Y6 using the FPV Manual kit.  He must have started with arms at least 80cm long.  All using the 10mm stock.  Well, when it took off, the arms would get into an oscillation with the center deck probably bouncing up and down a good 5cm.  It was amazing it could fly at all (he was using a Naza FC) made a really awesome thwapping noise, and was kind of captivating to watch the rhythmic pulsing.  But I was convinced it was going to kill us all with those 12 spinning knives.

He started cutting them shorter and shorter until now, I'd guess they're about 20-25 cm long.  The thing looks kind of funny but flies well.

I think the type of wood used has a big impact as well.  I used ash wood (figured if it was good for baseball bats it'd be good for arms).  My buddy used poplar - I believe because he thought it'd be light.  But it is definitely springier than mine.

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DeveloperPermalink Reply by Randy on June 22, 2012 at 11:39am

Yes, re the crash after changing to 3S batteries...I totally agree with Glenn M.  The throttle trim would likely be much higher for 3s vs a 4s.  It's adjusted automatically during flight and saved to your eeprom (when you disarm the motors).  I would have expected the throttle trim to have reset to the new value required values if you held a stable hover for about 15 seconds.

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Permalink Reply by Bruce Jones on June 22, 2012 at 12:22pm

OK, I'll remember to do that in the future.

But for other people who get in the same situation, is there any way the code could be modified to prevent total failure?  I'm worried about the safety issues.  I barely missed hitting another guy flying at the field when I lost power.  If I hadn't yelled and he hadn't responded very quickly he would have been hit.

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Permalink Reply by Gustav Kuhn on June 22, 2012 at 1:07am

Hi Bruce, I have the same camera, well, looks the same.

Just checked it with my Spectrum Analyzer, old HP 141, and yes, it is evil :-)

Generates a lot of RF noise well into the GPS frequency.

It probably killed you gps reception.

As for your other problem, I fly a quad, on 3S, weather has been really bad here, except when I'm at work, aargh!

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Permalink Reply by Bruce Jones on June 22, 2012 at 1:18am

Wow, that's really interesting about the camera.  I NEVER would have guessed that.  It looks so small and simple...

Could you do me a favor - wrap it with aluminum foil and see if your'e still getting evil rays of death out of it?  I'd appreciate it.

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