I finally found a GT-5.1V2 and 5.2 in stock!

[Polartip]

Originally Posted by gwright

You could possibly try some softer blades (more flex) so you could damp with the blades since the head must be stiff. I really don't think you'll ever eliminate the issue with gyro settings, as that's not the problem in the first place.
do you have head without those links,..i.e. a "normal" style head? I wouldn't think you'd want to run the stiff linkage head at low rpm anyway,..the repeated stress on those links when it teeters is just asking for failure. Back many years ago some folks played with stiff heads, literally JB welding the blade axle into the head block and dial indicating it EXACTLY centered. No, I would NEVER suggest doing this. Those heads were plastic (cheap to replace) and we ran far far lower rpms. Still kinda dangerous now that I think about it,..but I digress. The point I wanted to make is they had to experiment with MANY blades to find some more flexible rotorblades that would effectively provide the damping.

On another note, I hope to have a 550fbl in the air soon, and when that happens I'd be happy to share settings that I end up with. With the software and cable I could just post a setup file.I installed a 9 tooth pinion, instead of the stock 11 tooth since I want lower rpms without heating things up, and longer flights. something I always run into with the slower setups is getting the tail to work well. The designers want to make something that appeals to the majority, so they usually work best at the more common high rpm ranges. I found there's an 8 tooth pulley available for the tail of other raptors and it will of course fit in the 550, so I put it in last night. Stock is 9, resulting in 4.55 tail ratio if i counted the teeth correctly on the front pully. the 8 tooth should be 5.1 or thereabouts. If you're gonna spin the head up like most people I wouldn't recommend it, the tail would be really whirring, but at the planned lower rpms it should help a lot. Due to these differences, I'm not sure how useful my GT5.2 settings will be, but I'd be happy to share when done. I'm not sure when we'll have weather to fly and I'll be able to get it in the air though. This weekend would be good but I have family responsibilities.

This sounds like the the logical course to take, everywhere I've asked it seems that the 500 size and more so with the dfc head does not like the low headspeed. Do you know of any carbon blades that would be less stiff in this size? Are you a fan of the Kontronik governors or do you mostly adjust thru pinion size. I Have read that there is advantages and disadvantages with regard to bigger pinion and lower curve and visa versa... But the subject is mildly confusing.

Should have the family join in on the 550 fun, that way you're getting 2 birds with one stone... Would love to see some of the config.

[Bladecpnitro]

Originally Posted by Polartip

Jip, tried all the gain adjustments I could Stomach... Might be to low on the rpm's tho, Trying for 1600 rpm. Not giving up tho. Shes also losing the tail a bit, but I'm sure this will be easier to solve... Probably get some bigger tail rotor blades as I've heard Gary mention in other posts.

Oh! For low headspeeds you need higher swash P gain and I gain settings, I didn't catch the low headspeed part.

[gwright]

I don't use Kontroniks ESC's,.. I generally use JETI products (spins and mezon's), so I cant comment other than I always hear how they have the best governers available. You generally don't hear negative comments on kontroniks.

As for blades, I think you're going to have to search for fiberglass or wood. Carbons are going to be too stiff. You could always treat the problem rather than the symptoms,.. install a swash follower, normal links, and softer damping. The damping is the issue, but if you soften the damping, those style links will be under extreme loads and I'd worry about fail. Additionally, when you soften damping you're going to have to worry about boom strikes, and I think that head design is lower, so the blades are even closer to the boom. I could get extremely verbose about my opinions on those direct linkage head designs,.. but I digress.......

For your tailrotor,..longer blades and speed it up if possible. It seems 4.7~5.0 tail ratios were standard for the longest time, and now with headspeeds going through the stratosphere the manufacturers are lowering tail ratios, probably for safety, which is a good thing. Unfortunately, those of us that want to run more sensible rpms are left with developing other solutions. On my E720 I actually had someone make a speed up tail gear to get it from 4.6ish to just over 5.0. He doesn't want to produce these in quantity, so no, i wouldn't ask . I run either 115/s or 120's on those machines (and will try 130's when they're in stock again). Please understand though, when you change ratios or use longer blades,.etc. that the manuf didn't consider his during design, so you're accepting responsibility if something breaks due to the higher loads.


As for the gains,.. I've always found that the swash gain works inverse to the tail. As you speed up the head you have to of course drop the tail gain as we've known for years,.. but I've found i can run far higher swash gains in higher rpms. It doesn't make sense to me either <G>, except that maybe the control loop speed is the issue. Not the amplitude of control but the speed. Sort of like if you used servos that were .5 sec transit and swapped them for .1 sec transit. You speed up a component of a closed loop and you can speed up everything else (gains). Maybe the tail is allready quick enough, and the higher rpms increase the amplitude of correction too much, resulting in needing lower gains. I love a good brain teaser, but I dunno on this one, just what I've noticed in use.

As for lower rpm setups, always better to drop pinion and/or motor KV than to just run lower throttle/governer. You end up overgeared and the current spikes can be tremendous. for instance, one of my machines had lots of headroom, and I was at 1750/1300 on the headspeeds. Current spikes would hit 160~170 in flight, average current in the mid 20's. Not too high, things not too hot, everything OK, but I wanted more efficiency. I regeared, and with governer I could tell absolutely no difference in flight power. Started dropping timing on ESC (was at 20 degree advance to start, which is my common starting point on low KV outrunners from hacker). When I hit something really low, like 8 or 10 degrees advance, I started loading a bit,.. not enough headroom. As timing is raised and lowered, a side effect is it raises/lowers KV, so for the effective kv at 20 degrees I was fine, at 8 I didn't have enough headroom. Keep in mind we're splitting hairs here, even at 20 degrees we're talking less than a 10% increase in KV). I ended up somewhere around 12 or 14 degrees timing advance to have zero loading (just barely enough headroom, but it's enough). Temps on battery and ESC were showing under 100 degrees in summer, motor a little over 100. Highest recorded current spike was 109 amps (down from 160~170), average current much lower, in the low teens now. flight time of course was extended. Deeper gearing for less headroom, but same rpms and pitch, same flight performance, from around 12 minutes up to 16-ish minutes with 1300 rpm the whole time. Since I fly a mix of rpms flipping back and forth I set my timer at a conservative 10 minutes on that machine.

Polar,.. no kids to "join in", just my wife, and she came home saturday after 3 months in the hospital, two in ICU on life support,.. so you can understand why heli's haven't been my prime priority.

[Bladecpnitro]

Tower Hobbies finally has the Ace GT 5.2 in stock in the US 199.99
http://www3.towerhobbies.com/cgi-bin...?&I=LXEANP&P=7
It looks great, I think the black looked better though.

[radu7]

Yeah, I liked the black look better as well. I guess the white face will help keep the unit cooler if it is mounted on the heli in a place where the sun will hit it for any length of time. Hopefully it's a kind of white plastic that won't turn yellow and look like crap after a while. Not that it would affect how it operates.

[Polartip]

Just purchased the 5.2... Should be arriving in South Africa in a week or so. Cant wait!