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Old May 02, 2013, 01:19 PM
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RCG Goblin Heli thread

There must be guys here flying these awesome things. And no discussion going on. So if anyone wants to chat about anything concerning the Goblin helicopters in any size. We need this thread and this is your spot.
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Old May 03, 2013, 03:50 AM
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Luvmyhelis,
I fly the G770 and just don't have any issues with it, it's an awesome bird.
One modification that I did do was the KDE performance tail control on my ship, just because I appreciated the design. On installation I found it would bind, but it wasn't an issue with the KDE control linkage, it was the 770's tail box mounting to the tail boom. The tail box is a square assembly and the tail boom is tapered causing gaps to exist between the two so when bolting up the two together the tail boom would warp the flat side plates of the tail box.
The side plates have the support bearings for the tail rotor shaft so the shaft would now be out of square with the side plates causing a bind between the tail control slider and tail shaft
My fix was to place shims in the gaps that existed between the tail box and boom so the warping of the side plates could not happen when torqueing the tail box to tail boom screws.
I also added a Jeti Anti Spark bullet connector to my positive battery lead to the ESC to get rid of the big arc from the battery while plugging in, that worked perfectly.
Most of my ships I see something that I need to change in an effort to make them better, at least in my mind, but when looking at the 770 I just shrug and say AEYYYYY like Fonzie looking at himself in the mirror of the old Happy Day's show.

I have enjoyed your work and contributions in the past.

RCG has not been a hot bed for SAB discussions but maybe something will get going.
Somebody out there may have an issue or curiosity with SAB for discussion.

Viking
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Old May 03, 2013, 12:24 PM
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Good post Viking. I was looking at the very same Kde dual control pitch slider myself for my G700. I hate single control tail sliders with a passion. Even as well built as the Goblin is, the tail still has that single control slider slop I detest. I even contacted Bob at RcTek to help me machine out a new tri tail rotor to see if I can pick up some extra torque back there and drop my tail blade diameter down just a tad. I hate my blades nicking the grass on landings and spool ups.

I hear you on how well designed these are. Abec 5 bearings everywhere and every single part just fits! I am still running the factory rigid fbl head and just love it. However the Sab blades were not balanced real well. I run Zweave 720s instead.

One of the few things I did have to mod is the tail belt tension roller. Any roller that is seated around threaded bolts will wobble/chatter due to the slop between it and the smaller bolt threads. So I ran a shanked or un threaded bolt through the bearing areas there and it cleaned up the tension roller dramatically.

What really gets me, is no matter where I take this thing. It is always the heli that draws the crowds. Everyone wants to handle it and check it out. My other customs sit there like the invisible man.

But on wed after a series of high speed loops I smoked my esc. My first auto under duress! And soooo glad I was running a separate battery on the RX at that moment.

Viking, what are your electronics?
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Old May 03, 2013, 01:25 PM
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I hear you on the shanked bolt, it's just good engineering.
I have a tendency to stick with what has worked for me in the past on the electronic side so this is my setup:
AR7200BX
Savox Servo's
CC Ice2 HV 160A 50V ESC
CC Pro BEC
Spektrum Sat
Pulse 5000mAh 65c battery
All of these parts have done well for me on other ships and it keep's it simple for me to set it up.
I am looking forward to eventual changes in my electronic package, only because change can be good! However I do get lazy so unless the present gear gives me a problem, I may never change.
I am not a smack flyer nor do I strive to become one but what I really personally appreciate is smooth maneuvers and transitions, that is my goal...relaxing beautiful flight The 770 has the power and stability that it will naturally allow smooth transitions and 3D flight which is what I am after. I'll chase my TRex 250 around the field then pick up the 770 and relax on the sticks. If one want's, it can still be very fast, but if one wants, it can be very slow and precise through the maneuver as well.
To get to the flight ability I personally want will take me a long time but I am will to put that time in, it's just a blast.
Power and stability...gota love it.

...I have contemplated running a separate battery for the RX as you have done for the same reason. It's not a question of "if" it will happen but "when". Hopefully I will have changed over by that time.
What's your setup for that?

Viking
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Old May 03, 2013, 03:38 PM
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I picked up a Pulse 2s 7.4v 2550ma Rx batt that is riding on a velcro strip along with a velcro strap underneath on the lower thin body tray. I did mount up a ProBec on a few test hovers trying to diagnose some setup issues with my gov earlier, but I took it off the minute my Rx pack showed up in the mail.

I had a ProBec burn all my $$$ Mks servos and Sk720 last fall so I won't be using one of those again on a heli if I can get around it. (In fact I just left a message with Thomas at MKS USA an hour ago about the replacement set I am ordering this weekend) Also had two of the Ice esc's burn down my helis.
But believe it or not I still run their HV esc's in my 6s and 12s 420mm stretched 450 prototypes due to their superior phasing speeds. No other controller will run my custom motors. And am seriously thinking of adding a new Castle Phoenix Edge HV130 to the Gob. I like the data logging and hopefully the days of Castle cremations are over? I like the idea of a cap pack to help regulate voltage ripples now though after this last weeks esc failure on mine as I will explain.

As you know, the Castle controllers can be tuned to give wicked rpm response. I can't get any of my other esc's even close. Plus now there is a way to couple them with the Skookum Robotics and Vbar fbl controllers for the gov. And the Sk540 gov pumps the pitch at the same time as the Rpm ramp slightly before the blade load hits. The response is real hard to describe since it is proactive instead of reactive. Going through any hard transition where the normal esc gov changes in head speed tend to make a guy alter his gymbals in response are gone. Rolls, loops and twists, high speed banks and such are seamless. The difference between my Ice esc on gov, ( or any other esc for that matter) and the Skookum gov are night and day.

Bottom line, it makes me look like a far better pilot. I can live with that....

Wednesday when I fried my Goblins esc on its last flight of the day, and probably toasted the wiring in my new Scorp to boot. I had earlier let one of our clubs more advanced fliers take the Goblin up. He is running the same fbl controller you have and a BeastX on his 6Hv's. The Sk540, even with 10 expo was so lively it scared him. To me the others feel numb after flying these fbl controllers for a while now. And the moves feel so much more precise and connected. Some guys were complaining of small head bobbles with the Sk540 and the rigid head but I can't get mine to. I also took it in a 30mph wind gusty flight from one side of our huge flying field, to the other and back going sideways against the wind and never touched the tail once. It stayed perfectly nailed in the correct position. That was impressive.
Anyways. During the last full blast high speed loop of the day. Right after the apex at the bottom as I was slowing down we could all hear the motor start sputtering. And I was suddenly in my first real forced auto.

So as of today after fighting through another total teardown and replacing the esc and motor. Here is my equipment list.

Scorp 4035-630 is gone and replaced with a wimpy AlignBL750-MX 530kv.

Yep HV120 (YGE clone) with heat sink.
HK Magnetic induction 70360 cyclics and 70960 on the tail.
Zippy 40c 5000ma packs using the CF sliding battery tray mod. Pulse Rx batt.
720mm Z weave blades. Stock tail.
Sk540 w power bus on the Sab fbl support pad.

And other than that, unbelievably. There are no other custom mods than a simple bolt on the tension roller on the entire heli. Unlike all my other Align and Compass helis that are basically total customs and aren't nearly as well built.

Just as a side note. I talked to Thomas for hours and got the rare opportunity to interview him a few times recently. What an incredible guy is all I can say. But in one talk. We discussed the Bec issue on not only helis but on planes. Thomas told me the #1 reason most servos come back damaged is due to Bec failures. Most bec's when they fail, end up routing full voltage through them as they go. Destroying everything connected to them. So he adamantly hates Bec's with a passion. And flat out told me that if there is any way to mount a separate flight pack anywhere. Do it.

LMH

P.S. Thomas from Mks just called back. Mks HBL669 and 665 servos on their way..
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Old May 04, 2013, 08:13 AM
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So how much is left in the Pulse 2s 7.4v 2550ma Rx battery after a flight?
Not sure but a two cell Pulse may be less weight than the CC Pro Bec which would be good as well. I may have to drift that direction and give the RX battery a try just for piece of mind, simpler is always better from a reliability point of you and there is one thing you must never loose while flying anything and that is control. You can loose motor power, but you can't loose your control input so battery power to the RX helps ensure control function continues, I like it.
The thin lower body tray you have your battery mounted to, that is where I have the BEC mounted at this time (soon to be a battery pack for the RX) and I noticed on my 770 that it was very flexible and could contribute to amplifying any vibration in that area from the weight of the BEC. I used a couple of thin strips of the foam from the parts trays in my kit between the top and lower body tray to make the tray ridged to prevent vibration. Worked perfectly.
I cut the foam slightly thicker that the dimension between the plates so when assembled I would have a slight compression to the foam and on assembly only glued one side of the foam to only one plate so in the future I could pull the two plates apart if needed.
Anyway with your battery pack mounted there if you notice it has the ability to vibrate, the foam is a positive, light weight fix.

Glad you auto went well, nothing like surprises when flying helicopters.

Viking
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Old May 04, 2013, 03:26 PM
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I think I better remember to post how much I use on the Rx pack the next few times out. Plus with my new Mks servos that will change things for sure also. It will change of coarse on the length of flight times and how drastically I alter the flight styles. My flight yesterday with the new Align motor drew so many less amps than the much more powerful Scorp I had on it. I went well over 8 minutes and was still flying with lots of batt still left when I brought it down. But talk about much less overall power! The Scorp gave me 6 min flights safely and 7 pushing it to soft cutoff. But I could bake and shake with that motor. What do the 700 guys do with the Align motor? Just hover around?
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Old May 05, 2013, 10:13 PM
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Looks like a total rebuild is in order now. I do mean total. I added up the parts after today's fiasco and it comes close to $700.
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Old May 06, 2013, 06:10 AM
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Originally Posted by Luvmyhelis View Post
Looks like a total rebuild is in order now. I do mean total. I added up the parts after today's fiasco and it comes close to $700.

That doesn't sound good, what happened?

Viking
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Old May 06, 2013, 09:11 AM
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Originally Posted by Luvmyhelis View Post
Looks like a total rebuild is in order now. I do mean total. I added up the parts after today's fiasco and it comes close to $700.
Those words are never good to hear.
My worst fear in flying the big ones
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Old May 06, 2013, 10:34 AM
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That doesn't sound good, what happened?

Viking
Very very poor decision making on my end. I was showing off when I should have just landed it. Wasn't feeling 100% and literally dumb thumbed it, but may have had a stripped servo arm that contributed. Right around center flip the heli responded in a whole different way. I barely had time to hit TH before it tanked full tilt. Honestly I was up sweating at 3am still traumatized and mad as heck at myself. One, had I been flying in our normal club field, with much more visibility and room. That is where to hot dog things. Not where I was. Two, I hit TH due to the fact that I heard kids talking that were gathered under a tree less than 100 ft from where it came down in a semi twist less than 15 ft above the ground. Partially visibly blocked. And it was moving fast. The thought of flying out of it died in a millisecond and I knew the instant I hit TH things were gonna get ugly. The mental image of it hurting anyone will stick with me forever.

Speaking of moving fast. Is the larger Gob even faster?

Quote:
Originally Posted by jombo View Post
Those words are never good to hear.
My worst fear in flying the big ones
Yeah, my luck. If it can, and I have it. It will. If I can save my esc, and one of the servo gear sets. I can knock about $160 off that earlier figure though. Still
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Old May 07, 2013, 07:41 AM
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Sorry to hear all that and I feel your pain. I just had a similar crash with my T250 training ship that went very similar. I fly in a very small area flanked by trees on three sides and my house on the forth. I usually stay high to use the skyline as a visual backdrop for attitude detail but in this case I decided to fly lower and got in the three shadows moving fast doing flips and just lost sight of it and from that all control. Another lesson learned, and I did know better.
The 770 is deceptively fast, it's big, but accelerates very quickly.
I had flown most of one day with the T250 and decided to get the 770 out...forgot to tell my thumbs I changed ships, luckily on the first flip when I pushed hard into negative pitch, as I do with the little ship, I had plenty of vertical space to fly in because the 770 just disappeared straight up and out still rotating through the flip.
Spent the rest of the flight being very aware of my control input and let my eyes dictate how much and when the sticks were moved and not just relying on remembered stick movement.
Biggest thing for me to remember this summer is to stay out of the tree shadows, it's costly.

Viking
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Old May 07, 2013, 02:08 PM
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Sorry to hear all that and I feel your pain. I just had a similar crash with my T250 training ship that went very similar. I fly in a very small area flanked by trees on three sides and my house on the forth. I usually stay high to use the skyline as a visual backdrop for attitude detail but in this case I decided to fly lower and got in the three shadows moving fast doing flips and just lost sight of it and from that all control. Another lesson learned, and I did know better.
The 770 is deceptively fast, it's big, but accelerates very quickly.
I had flown most of one day with the T250 and decided to get the 770 out...forgot to tell my thumbs I changed ships, luckily on the first flip when I pushed hard into negative pitch, as I do with the little ship, I had plenty of vertical space to fly in because the 770 just disappeared straight up and out still rotating through the flip.
Spent the rest of the flight being very aware of my control input and let my eyes dictate how much and when the sticks were moved and not just relying on remembered stick movement.
Biggest thing for me to remember this summer is to stay out of the tree shadows, it's costly.

Viking
Yeah, the space required for the big guys is critical. Lesson learned on my part, no hot dogging unless I have the room. No matter how good you are, there is a moment where something will deviate. Having room to adjust is def needed. I just got a 250 together late last night. Sadly every part on this kit seemed to be defective. I almost have enough to build two of them now. The second being a total pile though.....

I did spend hours yesterday practicing linked stationary side and back flips on the sim. Cyclic pitch timing has to be instinctive to get them just perfect. Funny thing, the day before I trashed the Gob, I was doing those effortlessly in the same spot. Dead on perfect. The next day? Bam..........
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Old May 11, 2013, 03:58 PM
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I have my Goblin setup on a 2s lipo for a rx pack as well. I generally use 200-250 mah per flight. I have (3) BLS 451s on cyclic, a BLS 251 on the tail with a Spektrum VR5203 step down to 6V, Mega Power 120HV ESC, Quantum 4530-500KV motor, VBAR 5.3 pro, VBAR GOV, SAB mains and tails, Custom canopy and boom.....love it!!!!
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Old May 11, 2013, 04:52 PM
Need More PURPLE !!
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Hey Goblin crowd.

Whats the "limited edition" G-500..Upgrades ? comes with an Ikon


http://helidirect.com/sab-goblin-500...on-p-30951.hdx


Extremely nice pics & set up laughingstill -Drool-
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