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Post by dunkonu23 on Feb 7, 2011 12:27:03 GMT -5
Yeah, I think that's what's happening too, Bill. I've only stripped (well, melted one gear) since I've had my 550 and that was with stupid head speed (which I'm still seeking), but I digress. Hang in there, Robby. We'll get you going! Scott
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Doozer
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Post by Doozer on Feb 7, 2011 16:05:21 GMT -5
Looking at the pinion through the bottom ... It looks like the pinion I'm using is wrong for the gear. I'm using a pinion I bought at my LHS... it's an Align pinion. I have it pushed up as far as it will go and it still doesn't look as close as it should. I feel fairly dumb at this point. All e is out of Gaui pinions so I just shelf it until I can get the correct pinion.
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Post by dunkonu23 on Feb 7, 2011 16:16:26 GMT -5
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Doozer
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Post by Doozer on Feb 7, 2011 18:49:05 GMT -5
Thank you sir! Pinions on the way.
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Post by dunkonu23 on Feb 7, 2011 19:14:00 GMT -5
Great! And, you're welcome. Can't wait to hear that it's sorted and in the air! Scott
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Post by billmay on Feb 7, 2011 23:15:16 GMT -5
With enough discussion, the truth will always prevail!! ;D Bill
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Doozer
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Post by Doozer on Feb 7, 2011 23:29:55 GMT -5
the funny thing is. I've flown that pinion (type, not the same one) since I built it. I flew many, many flights with it before the first strip. I didn't suspect it until I looked at it. I've always just kind of gone by feel. Not anymore . Thanks again guys.
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Doozer
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Post by Doozer on Feb 12, 2011 19:30:31 GMT -5
Got my pinions ::does cabbage patch::
I'll be flying tomorrow if the wind doesn't pick up to much. I have two pinions 13t and 15t. My grips are plastic, but the blades are carbon, so I'll run the 13 with the 60 front. 13/60/19/61 that should put me in the 1800 to 1900 rpm ball park.... i think. I used a downloadble head speed calculator. If I'm wrong tell me so I don't have this thing vaporize in mid air.
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Post by Jerrymac on Feb 12, 2011 22:01:01 GMT -5
What head speed were you running with the plastic grips and 430mm blades?
You might want something around 2200 to 2300 with 500's, but I am not sure what the plastic grips are rated for. I run about 1900 to 2000 on my long-boomed Hurri running 550mm blades and plastic grips.
I use the cnc grips on my 425 because I run a head speed of around 2900 to 3000.
Efficiency ratings seem to be a little suspect on the Z-Power motors to me. I think they are a little more efficient than the stated rating. You might be a little closer to 2000 with that gearing if you are still running the Z20-1470.
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Post by dunkonu23 on Feb 12, 2011 23:58:20 GMT -5
I'm with Jerry. I think your headspeed is a little low. If you get a wobble on liftoff into hover, you'll know that immediately. I've seen a person running 2800 on plastic grips with a 425. I wouldn't recommend that, though. I'd probably start at around 2300 and move up gradually from there.
Scott
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Doozer
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Post by Doozer on Feb 13, 2011 13:38:29 GMT -5
Alright, thanks for the input. I can get to approximately 2300 with the 15t pinion, but I think I'm going to try 13t first. I'll see if I can get a graph out of my CC ESC.
Another question. If I stretch it to swing 500's what motor should I use? I'm using the Z20 1470Kv... maybe the 980kv or the Z30 1100kv. I'm also using mini servos, should I switch those out too?
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Post by Jerrymac on Feb 13, 2011 15:00:44 GMT -5
On the motor, you could try the 1470kv geared for around 2200 to 2300 running 500mm blades and see how it flys. If it bogs too much then go for the Z30-1100. If I remember right, I think Ivan (9sec240) was using a 1600kv motor in his 425 and re-geared it after stretching to 500's. Maybe he can offer some input on that. I personally chose the Z30-1100 for my HeadHunter build which will be using the medium boom and 500mm blades.
On the servos, I have never used mini's on any of my Hurri's so I can't really comment there. Mine all have full sized servos on them, except for my 425 which has a JR DS3500 tail servo on it which is a mini servo.
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Doozer
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Post by Doozer on Feb 13, 2011 16:01:58 GMT -5
Well....
Everything was perfect except the head speed. It was a lot lower than I remember. No punch at all. However, there wasn't any wobble when I loaded the blades up and it stayed in a cyclic hand free hover with no noticeable drift (tail in, tail left/right, and nose in). I did some circuits, figure 8's, and some pirouetting stall turns, but I was sketched out at the thought of going inverted with the head speed so low. So I didn't.
Piro speed both ways was nice... a little faster with torque so I'll dial some of that out (Through my CY Solid G). There was no wag, and no pitch up in FFF. It was noticeably more quiet with the correct pinion, and best of all... no gear strip.
I'm going to change the pinion to the 15t and see how that feels. I haven't started charging the battery yet so I don't know what my mAh out was. My guess is that after 7 minutes of flying I probably took it to 40%. I decided to keep flying after the 5 min timer went off because there was not a real drop in power. The motor was a little warmer than my body temp. I had to really press to feel any heat at all. I could not feel any warmth from the battery.
So it was a good trip, I flew a few other helis as well. 72 degress and a mild > 5mph breeze. It did gust a few times above 10 mph because I fly in the only open area between two mountains and some housing sub divisions (wind tunnel.. sort of). Bigger helis are more fun!!! I don't think I want to fly smaller than a 500 anymore... unless I'm inside. My G5 didn't feel as good as my Gaui, and I love that 450.
Anyway, before I order the stretch, I'm going to wait to see how it behaves with the 15t pinion. I'm not a huge fan of metal in the head, I just don't need it for the way I fly, but if the metal grips are safer, I'll spring for them. I had a lot of fun today!
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Post by dunkonu23 on Feb 13, 2011 16:31:41 GMT -5
Robby,
That's great news!!!! I'm happy for you, man! Now, if you decide to stretch it, I don't think keeping the mini servos is a good idea. The head loading may just overpower the servos. Plus, you will have more torque on the tail. It may work, but I'm always one for safety.
Scott
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Doozer
Junior Member
Posts: 68
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Post by Doozer on Feb 13, 2011 16:41:35 GMT -5
I'm ready for that HH frame whenever you are!! ;D
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Post by Jerrymac on Feb 13, 2011 19:41:51 GMT -5
Glad to hear you enjoyed your day flying. I can imagine how sluggish the collective was with those gears and 430mm blades. I use the Z20-1470 on my 425 running 15-50-20-61 gears. I has some insane pop on collective. Flight time suffers though, as I only get 4:00 with 6s 2500mah batteries.
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Post by dunkonu23 on Feb 14, 2011 4:48:43 GMT -5
I'm ready for that HH frame whenever you are!! ;D I hear you! As soon as I get the metal parts in I'll let you know. I've been E-mailing my machinist daily so... soon. Scott
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Doozer
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Post by Doozer on Mar 1, 2011 0:08:38 GMT -5
This heli's been flying so great. It's really become my favorite Electric heli. But man, I've had such a hard time getting more than a few flights out it without something going wrong. Not the heli's fault... it's the operator. I had to emergency auto again with this heli. All I did was break a landing strut and the Tail Stabilizer. I had to auto because the motor stopped while coming out of a stall turn. Freaked me out a bit because I wasn't expecting it.
So I tore everything down... all shafts are straight, links straight, no cracks in the grips. This was a case where breaking a couple of 7 dollar parts was worth it. What was the problem? The red motor wire from the Z20 had been rubbing against a motor mount screw and was exposed. A few strands had broken and this was causing the motor to stop running. I soldered the broken strands together, as best I could, then triple wrapped it with heat shrink tubing. Plugged it up and, it spooled up fine.
I'm still worried though. I'm not sure I will have much fun with it as is. So I'm going to stretch it to 500 and get a new motor. Taking suggestions on the motor.
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Post by Jerrymac on Mar 1, 2011 1:39:55 GMT -5
Glad to hear that you are enjoying your 425. Right now, the 425 is my favorite heli to fly too, but that could change when I get the HeadHunter "500" finished.
There are 2 motors that come to mind that seem to work well for 500mm and 550mm blades, but, both come with a drawback. The Z30-1100kv is very popular, and that is what I put in my HH build, but it is taller than the Z20 and hits the canopy so you have to trim the canopy out around the top of the motor. A few guys, and I believe Scott is one of them, are using the Scorpion 4020-1100, but, it is too large in diameter to fit between the pitch and roll levers on the stock plastic frame. Not sure about the height on the Scorpion though, if it fits under the canopy.
Even if you decide to go with a HeadHunter frame, you will have to trim the canopy for the top of the Z30 motor to stick out. Hopefully Scott will chime in and let you know how the 4020 fit in his HH frame.
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Post by dunkonu23 on Mar 1, 2011 5:29:55 GMT -5
I have no fitting problem with the 4020 1100 on my HeadHunters. Fits just fine. Heavy thing, though... you have to move electronics around for CG accuracy, but it's a great motor. Keep it oiled!
Scott
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