APM 2.5

[jolyboy]

Good to hear from you mate! Your build sounds interesting. Can't wait to see pics.

That regulator is good, I have one and used it for the same exact purpose as you but now I have a different setup. The black button thingy is an inductor (a coil of wire). Its used with the capacitors to smooth the DC output.

[R_Lefebvre]

Salience, so you flew the 500 direct-drive machine? How did it go??? Any photos of the finished machine before you took it apart?

[salience]

Not yet! Still stuffing the frames with equipment. The crashes were with the old geared version I've been flying/testing for the past several months. The new one should be ready soon - still waiting on servos from HK and a couple of other things. It will be a 3D machine (Double Direct Drive...;>)

[jolyboy]

Finished flying for the week. Got a ton of videos, but unfortunately none of them are very good. Just couldnt get this heli to perform as I'd like. The vid below is probably the best because all of the others were just simple tests flights

Watch for the attempted piro flying into the wind at 75km/h @ 2:37 hahaha



The aim was to dial it in and get a heap of logs to use in proving that piro comp is safe, but the entire 2 days were used trying to get the heli to fly stable. No matter what I did I just couldnt get this thing to fly like my previous setups did. I put it all down to weight. This heli is much heavier than any of my previous helis and handles accordingly. Its an absolute pig to fly lol --- handles like a wet mop.

So anyway, its likely gonna be about 7 months before I get to fly again (going away for work) so his gives me a lot to think about. I think the next build is going to be a light, FAST 3D machine, and the Chase 360 frame I have sitting in my lounge is the likely candidate. I'll probably get a VR uBrain as its small and light and runs arducopter. The motor I have for the chase is rated to >1500W so should be fun Think 3mins @ 160km/h and you'll know what I'm talking about heheheh.

[salience]

What lens in that camera - 2.1.... 2.8mm?
SEVEN MONTHS?
Well, the thread will miss you!

[jolyboy]

Its "Lens D" on the Möbius camera, I think its 2.1 or 1.8 mm. Really good for FPV flying because you can see all around yourself without having to always turn. But its also harder to fly precisely because its more difficult to feel the perspective depth in the image as you fly forwards. A longer lens like 2.8mm is better for precision as long as you keep moving forward at a reasonably decent speed because you get a better feel for the perspective depth, but its harder to look around.

Dont worry I'll be not flying for 7 months but I will be here and I will be conversing with you guys, feeling jealous of all your developments!!!!

[jolyboy]

I was about to hit the buy button for a VR Brain Micro, when I realised that it currently only supports a maximum of 6 channels in PPMSUM mode. WTF really? I had a look at the PX4, and its a good option for me

[jolyboy]

Looks like I don't have time to wait for the PX4, so this is happening:

[R_Lefebvre]

Originally Posted by jolyboy

The aim was to dial it in and get a heap of logs to use in proving that piro comp is safe, but the entire 2 days were used trying to get the heli to fly stable. No matter what I did I just couldnt get this thing to fly like my previous setups did. I put it all down to weight. This heli is much heavier than any of my previous helis and handles accordingly. Its an absolute pig to fly lol --- handles like a wet mop.

So anyway, its likely gonna be about 7 months before I get to fly again (going away for work) so his gives me a lot to think about. I think the next build is going to be a light, FAST 3D machine, and the Chase 360 frame I have sitting in my lounge is the likely candidate. I'll probably get a VR uBrain as its small and light and runs arducopter. The motor I have for the chase is rated to >1500W so should be fun Think 3mins @ 160km/h and you'll know what I'm talking about heheheh.

I imagine your situation is similar to my Protos 500 mapper. It's 3.2kg, almost double the standard weight, and running reduced headspeed. It's definitely sloppy. I think the issue really is simply that the rotor simply doesn't have enough authority over the airframe mass. First, the rotor is turning slow, so there's less cyclic power. And then, the effective stiffness of the head dampers is low, because the system mass is so high.

I think Delta-3 should help, but haven't gotten a round tuit yet.

[jolyboy]

I agree 100%. Its rotor control authority vs moment of inertia. In my case the roll axis flies perfect at all speeds, but the pitch axis is causing drama because if the massive (>3x stock) moment of inertia. I have video of my old 1.1kg trex450 at 2000rpm and its some of the most stable video I have seen with a hard mounted camera. As the moment of inertia becomes too much the head simply is not powerful enough to take full control of the heli. This heli that's causing me trouble is running a 4s 4000mah lipo, wayyyyy bigger than its meant to be. Plus it has that motor on the end of the tail which is increasing MoI drastically.

Re CCComp, i believe there is a point where no amount of optimisation helps, and physics is what is getting in the way. I think that's why CCComp worked so well on my old machine, and now its of little help TBH (my old machine was a less extreme case). This recent 380 machine gets me the most perfect stable rigid hover you can imagine (hovers horribly with CCComp off), but now its is causing extreme sloppiness at speeds greater than 80kmh. I turn CCComp off and I can fly 120kmh with the same head speed but it has this annoying shake that makes videos look very very bad. Its fine for UAV type flying.

I'm a bit tired of fiddling with this low rpm heli and really want to get a really solid machine to do some real flying. I'm hoping this chase 360 is going to be a good setup for me. Good news is a PX4 fits between the side frames with about 1.5mm either side! This heli will look cleaner than stock if I 3D print a mount for the PX4 because the wiring will be largely hidden. I also find the 3D printed mounts work well vibration wise because thick plastic don't resonate like thin carbon does.

[jolyboy]

Oh, one other thing you guys might be interested in:
This 4s 4000mah machine has the same flight time as my old 4s 2800mah machine, but the former flies half as well.

After this whole adventure trying to get long flight times I'm actually of the opinion that its more fun to have a 3D speed demon and just carry heaps of packs. With my new build I can have some 6s for insane 3D and some 3s packs for cruising around slowly. But in any case, the pitch axis moment of inertia is very small on this heli so it should fly really well at low HS.

[salience]

A TRex500 packed to the gills. ~3 kilos. Everything (almost) inside: APM, FrSky X8R bind mode 4, thus 8 channels via SBus converter to APM, channels 9-16 available directly from Rx. 60A YEP ESC to iPower 105Kv main motor, direct drive, 40A YEP ESC to iPower tail motor, CCBec Pro @7v for HV servos, MinimOSD, Teensy3.1 for SPort telemetry, 2 cameras, one with servo, camera switcher on ch11, servo on ch12, Immersion VTx, ESCs on chs 9&10, etc. It actually flies! Only one short test so far, needs some re-adjustments, (I had a rather misconstrued pitch curve and it took off like a shot - so at least I know it can rise quite rapidly!) but I hit a snag: the main motor / mainshaft coupling I devised is not satisfactory. In one of the photos you can see the nylon item, it fits into the motor and has a crossbolt for the mainshaft, but with my small Unimat lathe I couldn't turn something better. It should be in alu, and include a flat section that screws to the motor directly, rather than using the drilled-out plate from the supplied motor accerssories. The nylon affair is not quite true, and too flexible actually, so my vibrations are not as low as they could be. Any ideas for getting one made for me?

[jolyboy]

Wow!!!!!! That's a pack horse if I ever saw one. How on earth did you fit all that gear in there?

I hope it handles in the air OK. If you have any issues with the pitch axis, it will be better without the training gear on the tail boom.

The nylon part you speak of, does it need to bear any torque, or is it just a spacer? If it doesn't need to bear any torque, you can get a really accurate one 3D printed at shapeways.com. If you need a 3D model made, I can do one for you if you can supply the dimensions you need.

Another option would be to have it CNC cut from alloy in china.

[R_Lefebvre]

Cool, so it flies! Are you using 6S or 4S?

[salience]

yep, lotta wires in there. But easy to get to just by removing the port-side frame, which has very little attached to it. You can hardly see the APM in there, but it's actually mounted on one of those anti-vibe plates with the angled damper rubbers, directly under the mainshaft. The tail stand is actually quite light - a piece of 450 mainblade and a super-light practice golf ball - good for sliding over the rough terrain here rather than snagging something in a less than perfect landing.

on 6S, 3S for the tail.

the part should be alu - it centers the 8mm shaft inside the 13mm hole in the motor casing, and also screws to the top of the motor casing, and also has a cross bolt for the shaft at the top. In the picture it would be the (now) nylon top with crossbolt, the plate underneath it that screws to the motor casing, and another thinner section below, extending into the motor casing. In the present one, the plate squeezes a thinner plate of nylon to the motor casing, and is a devil to get true, since the nylon is a bit compressible, and my turning job not perfect. And I didn't have a bar of nylon of the full diameter, and if I had, it wouldn't have fit in the chuck of the lathe. See pics of motor below

Got any China addresses for enquiry?

[jolyboy]

I haven't used any myself, but a google search showed these guys, with CNC parts starting at $95
http://www.protolabs.com/firstcut

[salience]

Seems reasonable for a one-off job... but it would be more interesting if there were 6 or 7 of you also building a DDD 500 with an iPower 105 ;>)

I just ordered some alu bar stock - I'll give it another shot first - practice makes perfect I heard.

[salience]

Rather than send yet another 100 bucks to China I ordered some Al bar stock and some new lathe tools, including a nifty boring bar that'll do as small as 6mm holes. I wouldn't be surprised if most of that came from China, but at least I bought it Euro... The result looks good, certainly much better than the nylon thing in a previous photo. Just have to drill the crossbolt hole and mount the thing on the motor. The vibe graph will tell...

[sliver001]

Hello. I did verifying performance with dataflash logs in stabilize mode (in traditional heli 450) but the plot is bad - lines do not overlap. What could be the reason?

[R_Lefebvre]

Most common cause of that is the swash plate not being level, and/or not enough Rate I-term. Your Imax is 500, but you want this at least 1800, I normally run 4500, but you can only do this on the Full Parameters List.