700 Goblin 770 Comp

Smoggie

Well-Known Member
So this is my birthday and Christmas present to myself;)

It's the Goblin 770 Comp 'carbon edition' .. the carbon bit gets you a pure carbon canopy and tailboom plus a few upgrades of stuff like the swash, tail control mechanism and maingear. The 770 used basically the same mechanicals as the Goblin 630 and 700 but with larger frames and longer tail boom and main shaft.. plus longer blades obviously. It's a big old beast but because it shares mechanicals with it's smaller siblings the airframe is not much different in weight.

Being a scinflint I decided to use mainly hardware i had laying around or transferred from other helis. This meant no mega 14s power system, I'll use the 12s batteries from my trusty Compass 7HV. The full build spec is:

  • Motor: Kontronik Pyro 750 560Kv
  • ESC: YGE 160HV
  • FBL: Vbar Silverline
  • Servos: King Max HV Brushless all round
  • Batteries: 2 x Turnigy (or Zippy) 6s 5000mAh 40C
  • Rx power: 2s 2200mAh LiPo unregulated.

I had to cut the beefy 8mm shaft of the Pyro down to suit the Goblin, it had previously been fitted to a Mikado Logo which use really long shafts. Due to the relatively high Kv I also had to go down to the smallest motor pulley available at 18t. Otherwise it was a very straightforward build, much the same as the Goblin 630 I already own.

Surprisingly the 770 built up the the exact same flying weight as the 700 size Compass which was an encouraging sign as I was initially worries it might be a little underpowered with the setup i had (most people put 800 size motors and 14s in the 770)

So here are a few pictures:
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Flying opportunities have been limited by weather but it has flown and was pretty much setup spot on from the first flight. Power is ample, it really only needs 1700RPm to perform well but the motor will turn the rotors at 1950RPM and at that it's ballistic.

Anyway, here is an early flight in very windy conditions:
 
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holtneil

Active Member
Hi Steve through that was you with the kasama dune , do love the Goblin tho she is a gorgeous heli the King max servos do bring extra bling to the goblin bling
 

Smoggie

Well-Known Member
I've not been getting much flying in lately due to constant storms sweeping in but here's another flight of the 770 at low headspeed (1700RPM).. This heli doesn't need high RPM to fly well:
 
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D.O.G.

Goblin 380 Supporter
That is one sweet,colorful,beast of a bird you have smoggie. Good luck in taming that girl. Lol
 

Smoggie

Well-Known Member
While these big helis might be bit intimidating at first, to actually fly they are easier than smaller helis. The best way I can describe it is like flying in a slow motion replay, everything happens more slowly and smoothly. That's why i like them!

I've been tweaking the 770. The tail hold was a bit 'soft' at lower RPM, I had to almost max out the gyro gain to get it to hold well. So I've installed 115mm tail blades (stock were 108mm) and the smaller rear tail drive pulley to increase tail RPM a little. I'm looking forward to giving it a test flight but the weather's not cooperating.
 

holtneil

Active Member
Hi Steve she is lovely the weather is meant to be good this weekend between 5 and 7 degs so get those batteries ready , it's a pain only having the one pack for mine ,I don't think the 3000 mah from the 500 would work on my 630 so it's the last flight of the day rush home 're charge for the next day lol
 

Smoggie

Well-Known Member
Those 3000 packs would fly it, but it would be a bit tail heavy, and the flights quite short. But better than only having one flight!

- - - Updated - - -

Here's a little trick that might be useful for owners of 630, 700 and 770 Goblins...

The canopy on the Goblin is held only by two quick release studs at the rear plus the chin of the canopy locates in a slot where the landing gear meets the frame. This works well enough but the front-top of the canopy isn't supported and sometimes the canopy can end up sitting off centre, like this:
image.jpg
(Not my heli but mine was like this when built)

This can be due to the canopy being slightly deformed, and by the motor wires which run down the side of the frame forcing the canopy over to one side.

While it's not a big deal and doesnt effect performance of the heli in any way, it's irritating. So i fixed this by using a pair of canopy rubber supports from a Trex 800 (Align part number H80B009XXT)
h80b009xxw.jpg


These fit the Goblin as if 'meant to be', no trimming or adjustment required. You just need a couple of screws of the correct length, or cut down the ones that come with the supports.:
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The supports centre up the canopy perfectly:
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image.jpg

h80b009xxw.jpg
 

D.O.G.

Goblin 380 Supporter
Those rubber support work great. I don't have a gobby but I do have those supports on my 500.
 
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