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Post by Jerrymac on Apr 14, 2010 1:36:20 GMT -5
Scott, I spent a couple hours last night searching for info on the G770 on a bunch of sites. You know the saying, "put a dozen heli pilots in a room and ask a question",lol.
I do know that the 770 stops hard after a piro, as I have one on my 550. I also read of guys running TT tails that got rid of their 770 cause it stopped so hard it took the gears out. That is what confuses me about the 425. I must just have a set-up issue that I am missing.
My searching didn't help, as some guys said too high a gain will cause it, while others said too low a gain will cause it ,lol. Others said too much foam tape under the gyro causes it, and yes, others said not enough foam will cause it.
I think I will fiddle with the gain and also the rudder endpoints a little first. It seemed to bounce much worse in one direction than the other, although now I don't remember which way was worse. I looked over my mechanical set-up and didn't see anything that I think would cause a problem.
I generally don't let the stick snap back to center, at least not on purpose, but I fly thumbs and I have had my thumbs slip off the sticks more times than I would like. I almost flew the BH450 into my face last weekend because of that.
I had the BH pretty far out and my timer started beeping. I turned and started to fly it back toward me pretty fast. When it got close, I pulled back on the stick to stop, and my thumb slipped off the stick.
Hehe, this old fart got fast reflexes though, cause in the blink of an eye, I hit full collective and it went right up over my head. That is the second time that happened to me, only last time I ducked and almost crashed the heli too.
I have to get some more batteries for the Gaui 425 too. I only got 2 of them at first, to see how well I liked it. So far, other than the tail bounce I am liking it alot.
Jerry
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Post by dunkonu23 on Apr 14, 2010 5:43:07 GMT -5
In thinking about it, it may be the piro rates are too high. I know in the setup it said to set the rudder endpoints in the radio to 150.. in my way of thinking, that's pegging them!
Scott
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9sec240
Full Member
naturalasperiphobic
Posts: 261
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Post by 9sec240 on Apr 14, 2010 8:00:09 GMT -5
The JR stuff is quite odd for setups. On the G270 they want you to set up at 150% but then never mention backing it down but they DO say to be careful at over 100% on rudder EPAs..
How much expo are you running? I have found that expo will help soften stops and get rid of bounce.
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Post by dunkonu23 on Apr 14, 2010 22:51:29 GMT -5
The JR stuff is quite odd for setups. On the G270 they want you to set up at 150% but then never mention backing it down but they DO say to be careful at over 100% on rudder EPAs.. How much expo are you running? I have found that expo will help soften stops and get rid of bounce. Really odd! When I read the manual, I'm thinking the whole time.. this is really odd. You're right, the manual seems to leave things out. I'm thinking of looking to see Finless has a video on Jerry's gyro setup. I'd like to hear what he thinks about it. Scott |
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Post by dunkonu23 on Apr 14, 2010 23:15:26 GMT -5
Just now looking at the Finless videos on Jerry's gyro. Interesting. Finless is setting up dual rates to control pyro rates. He also says it's cool to lower the endpoints. Still watching... Here's a link to some setup info... You probably already have this Jerry... www.helifreak.com/showthread.php?t=78591Might want to take a look at your ball position on the servo arm, Jerry. Just a thought. If you're using the quad 3500G arm, I'm willing to bet you're on the last hole, something like 13-15mm from center and that may be too far out. Just a thought. Scott |
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Post by Jerrymac on Apr 15, 2010 2:00:52 GMT -5
Well, here is a little more info as far as the set-up goes.
I have the round wheel on the tail servo and the ball is out 10mm from center. The travel adjust on the gyro itself is at about 90 to 95%.
My rudder endpoints are 150 right, and 120 left. The piro rate was faster 'with' torque (which is normal) so I lowered the endpoint to get the piro rate close in both directions. Since it piros really fast I have the rudder dual rate at 80%.
I have the gyro gain at 32% using gear end points which would make the "true gain" about 22%. ( E.P. / 1.44 )
I have the rudder expo at 45%.
I might try increasing the gain next time I fly it to see what happens. The manual gives guidelines for gain for a Trex 450 and a Trex 600. Maybe something in between might work.
It says 63 for a 450 and 75 for a 600 using the gyro sense menu. That would be about 19 'true' gain for the 450 and 36 'true gain' for the 600. ( G.S.M. -50 X 1.44 )
Appreciate the help guys,thanks.
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Post by Jerrymac on Apr 19, 2010 4:20:01 GMT -5
Well, it was kinda cold (38F) and windy today, but I took the 425 out to the field again. I popped the tail control rod off at the servo and checked for any binding in the tail, and it was real smooth.
I flew 2 packs just doing some hovering, some punch outs and some forward and backward circles and 8's, and some quick piros. I fiddled with the gyro gain having the gear end point as low as 15 and as high as 45 and can't get rid of the bounce in the tail.
At 15 the tail seemed to 'hunt' a little, slowly drifting back and forth. At 25 it would hold good but started to bounce after a piro. At 32 it held rock solid on full collective punch outs, but even a slight right or left rudder input would cause it to bounce back and forth. At 45 the tail started wagging bad all the time.
At this point, I am not sure what to do with it. I am using the same gyro on the 550 with no problems. I might try some different tail blades to see if makes any difference as I am at a loss right now.
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Post by dunkonu23 on Apr 19, 2010 10:14:02 GMT -5
How's the belt tension, Jerry?
Scott
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Post by Jerrymac on Apr 20, 2010 3:02:15 GMT -5
How's the belt tension, Jerry? Scott Well, the 425 is still in the back of my truck, but I will check that tomorrow. Seems to me that I had the belt kinda loose when I first put it together and maybe it stretched a little more, I dunno, I will check that, Thanks. |
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Post by dunkonu23 on Apr 20, 2010 4:16:55 GMT -5
How's the belt tension, Jerry? Scott Well, the 425 is still in the back of my truck, but I will check that tomorrow. Seems to me that I had the belt kinda loose when I first put it together and maybe it stretched a little more, I dunno, I will check that, Thanks. My thought on the belt is that if it's loose it will do some things... slap around inside the boom--you might be able to hear it when you spool the helicopter down. Also, a loose belt might be prone snap against torque if there is any type of torque applied. Kind of like how you shoot a rubber band. Differential tension -- one side is loose while the torqued side is tight. On my 550 my belt has about 2mm of deflection--that's tight, but the tail is ROCK solid and does not exhibit any of the tendencies you described. Try it and let me know. Scott |
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Post by dunkonu23 on Apr 20, 2010 9:38:47 GMT -5
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Post by Jerrymac on Apr 24, 2010 20:56:48 GMT -5
Well guys, I am an idiot.  When setting up the tail I didn't realize that the gyro had the servo switch factory set to 'low' for an analog servo, especially since the gyro came boxed with a JR DS3500G servo. While checking everything over that you guys suggested and finding no problems, I was getting ready to switch out the gyro with the G770 that is on the 550 to see what happened. That is when I put my glasses on and noticed the servo switch on the gyro set to 'low'.  I just assumed that since it came with a digital servo the switch would have been set for it. Well we all know what the first part of "assume" means, and I feel like it. It is supposed to rain most of the day Sunday, but I am going to at least take it out in the yard for a few quick pyros to see if the bounce problem is solved. Thanks for the suggestions. Hope this cures the bounce. Jerry |
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Post by dunkonu23 on Apr 25, 2010 12:30:42 GMT -5
Well guys, I am an idiot. When setting up the tail I didn't realize that the gyro had the servo switch factory set to 'low' for an analog servo, especially since the gyro came boxed with a JR DS3500G servo. While checking everything over that you guys suggested and finding no problems, I was getting ready to switch out the gyro with the G770 that is on the 550 to see what happened. That is when I put my glasses on and noticed the servo switch on the gyro set to 'low'. I just assumed that since it came with a digital servo the switch would have been set for it. Well we all know what the first part of "assume" means, and I feel like it. It is supposed to rain most of the day Sunday, but I am going to at least take it out in the yard for a few quick pyros to see if the bounce problem is solved. Thanks for the suggestions. Hope this cures the bounce. Jerry It happens, bro. I'm just glad you got it sorted. Crappy weather here, too... well... Extremely windy.. gusts to 40. I know Ivan would brave it, but... LOL! Scott |
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Post by Jerrymac on Apr 25, 2010 22:30:50 GMT -5
Well, I kept an eye on the weather radar today and there was a slight break in the rain about 6:30pm, so off to the field I went. I started off with a warm-up flight with the BH450, and the motor quit about 1 minute into the flight. Not sure yet what happened, but was able to do a rather ugly auto that got it on the ground with no damage. Flew 2 packs with the Gaui 425 with the servo switch on the gyro now set to 'high' (Duh) and the tail held like a rock. No bounce at all even after some blazing piros. ;D Overall, I am real happy with the 425, except that I put a 14T pinion on it after putting a 15T by mistake the first time, and the punch-outs felt a little 'mushy'. I think I will put the 15T back on it. Now I just gotta figure out what happened to the 450.  |
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Doozer
Junior Member
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Post by Doozer on Apr 25, 2010 23:11:53 GMT -5
What do you think your flight times will be with the 15t pinion? I'm getting between 2500 and 2600 rpms with the 14t. I'd like to up that a bit, But I'm only getting 5.5 mins on the 2100mah hyperions. I think some better blades would help me a bit.
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Post by dunkonu23 on Apr 25, 2010 23:54:50 GMT -5
Sorry about your BH450, Jerry. I had problems like that from time to time on my BH500. I found cold solder joints on the motor barrel connectors. Funny thing is they got "cold" from the heating/cooling cycle. I'm glad you got it down without damage, though. I know how that pinion thing happens all too well.  I now mark my pinion gears with a sharpie or label so I know tooth count! Scott |
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Post by Jerrymac on Apr 26, 2010 1:30:01 GMT -5
Not sure what the flight times would be with the 15T pinion, but I will let you know as I am gonna put it back on. I have been breaking in some new lipos, so I have my timer set at 4 min. It flys pretty well with the 14T, but after having the 15T on it first, it just feels a little 'mushy' now. It never bogged with the 15T, but I was having trouble with the tail that ended up being unrelated to the head speed.
I will check out the BH450 this week, but I am thinking that the loud squeal I heard the last time I flew it might have been a motor bearing going bad, I dunno. I will check the solder connections though, as it made no smoke, or had any burning smell anywhere, it just basically fell out of the sky, and the motor would not spool back up after letting it cool down for a while.
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Post by Jerrymac on Jul 29, 2010 2:15:14 GMT -5
Well, I have had my 425 for about 3 or 4 months now and here is an update. I tinkered around a lot with different gearing, and had the head speed as low as 2500 and higher than 3000. I tinkered with different cyclic and blade pitches to see what a difference they made. Right now I am running a head speed of around 2700 to 2800 according to my calculations. ( Don't have a tach ). Have +- 13 degrees of blade pitch and 7 degrees of cyclic pitch. I am really happy with the way it flys, and it is now my "most flown" helicopter. I do still like flying my Hurri 550, but as I get better at flying, I just like the more nimble 425. As my flying skills get better, I think I will get a frame kit from Scott and transform it into a HeadHunter / Gaui 425. ;D I have only had one minor crash with it so far. The ball end of the elevator arm broke in flight and I lost elevator control. I was able to hit the TH and do a rather ugly nose in auto. It hit on the front of the skids then flipped over on it's head. The only damage was a slightly bent flybar, and of course, the broken elevator arm. Didn't even crack the cheap plastic canopy.  Overall, I am very pleased with the Gaui 425 and would recommend it to anybody that wants to build an inexpensive heli kit. |
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Post by dunkonu23 on Jul 29, 2010 15:48:25 GMT -5
Sounds great, Jerry! I'll let you know when the frames come in and I get kits prepared! Scott |
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Post by Jerrymac on Jul 30, 2010 1:01:28 GMT -5
Sounds great, Jerry! I'll let you know when the frames come in and I get kits prepared! Scott Cool Scott. Since these will be the new "G****y" HeadHunter kits, can I have mine engraved with the serial # 0001 somewhere on the frame?  |
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When setting up the tail I didn't realize that the gyro had the servo switch factory set to 'low' for an analog servo, especially since the gyro came boxed with a JR DS3500G servo.
I just assumed that since it came with a digital servo the switch would have been set for it. Well we all know what the first part of "assume" means, and I feel like it.
I now mark my pinion gears with a sharpie or label so I know tooth count! 
