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View Full Version : 10s Lower Headspeed Goblin? - Q. for SAB?


pitchandyaw
01-22-2012, 03:22 PM
I have a Logo 600se and have been very happy with it and the way it flies.

But I have been looking at the Goblin and I really love the design, the looks, estimated crash cost and ease of repair.

It seems:
- The weight of the goblin is the same if not lighter than the logo 600se
- The main blade diameter is the same.

And I know the gear/pinion options offer a lot of flexibility in configuration, so....

My question is:
Could I replace my Logo 600se with a Goblin and use it on 10s 5000 packs with a head speed of around 1800?

I know it's not going to be a hardcore smack machine at that head speed, but I don't need or want that. If it would give me similar performance to the logo 600se with the same packs, then I'm sold.

And as I get better, it can become a 12s monster later on ;)

Thoughts anyone? Thoughts SAB?

jhheli
01-22-2012, 05:22 PM
The SE is lighter and most SE run 690, the goblin can run 690 to 710s. I think you should give it a go, because you can run 1900 or 1950 to compensate for the little extra weight and get the same performance with a slightly lower flight time maybe not even that noticeable.

Dogdocphil
01-22-2012, 06:56 PM
Bert has run his at 1800 and it runs very well. Not hot enough for smack but very nice

LegndarySaiyan
01-22-2012, 06:58 PM
This is a similar question to the people asking if they can run 12s on the logo exxtreme. Short answer is yes it is possible, but in the long run, I think it's more economical to run 12s from the start if your seriously considering the goblin. 700 class is a 12s platform and the head speeds you prefer are still available on 12s. Changing to a 12s system later would require a different motor, pulley, and new packs so really what are you saving by running 10s in the interm?

jhheli
01-22-2012, 08:43 PM
You could use the same motor on 10s or 12s, if you use it on 10s then you would need a 26 tooth pinion/pulley if you use it on 12s then you would need a 22 tooth running the jive a 70% flat on either setup to achieve 1800 headspeed, and you would have to change a thing, though it is a 12s heli it is very versatile.

The good thing about the goblin is you can use just about every motor, because they have the pinion/pulley to go with just about any motor.

pitchandyaw
01-23-2012, 06:59 AM
This is a similar question to the people asking if they can run 12s on the logo exxtreme.

I understand your point, but I think this is actually quite a different question because:

- The xxtreme weighs a lot more than most 700's (the logo 600se & Goblin are very similar)
- The xxtreme uses a different class of motor from current 700's (the 600se & Goblin use the same class of motor)
- The xxtreme swings significantly larger blades than 700's (the 600se and Goblin swing the same, or very nearly the same, size blades)

pitchandyaw
01-23-2012, 07:10 AM
You could use the same motor on 10s or 12s, if you use it on 10s then you would need a 26 tooth pinion/pulley if you use it on 12s then you would need a 22 tooth running the jive a 70% flat on either setup to achieve 1800 headspeed, and you would have to change a thing, though it is a 12s heli it is very versatile.

The good thing about the goblin is you can use just about every motor, because they have the pinion/pulley to go with just about any motor.


The motor in question (coming out of the logo) is a Pyro 700-45. The speed controller would be a Jive.

Looking at the head speed calc on RH:
On 10s
Headspeed requested: 1800
Pinion suggested is: 26
Throttle 65%: 1718
Throttle 75%: 1822
Throttle 85%: 1926

On 12s (with the 26t from above):
Throttle 65%: 2061
Throttle 75%: 2186
Throttle 85%: 2311

This looks like exactly what I need; a nice flying lower head speed machine on 10s, but not crazy powerful.

This allows me to sell my logo and use the selection of new 5s 5000 packs on the Goblin.

Later, I can put in some 12s packs and have a much more powerful machine if I need.

It seems to work on paper, the only remaining question is actual flight experience on 10s - does anyone have that?

worldofmaya
01-23-2012, 12:07 PM
Not with a goblin, because there's none availabe by now.
But if you're interested in my experience with other models...
I build a custom Trex 700, TDR style at the beginning of last year, I had Logo from 500 3D to 600 XL ( rebuild to SE before Mikado) and I had a Henseleit TDR as 700 and 800 for the last 6 months.
I did low-rpm with my Logo, Trex and TDR. I think the TDR is the one which is close to the Goblin taking head - tail ratio, weight, Center of gravity and availabe motor - main rotor ratio...
First of let me say low-rpm here in Europe doesn't mean flying with 1700 - 1800rpm. My Logo 600 SE was used down to ~960rpm and flew up to 20min with 2x light 6s 3000mAh 20c in parallel.
I did the same with my Trex-TDR-clone which was a bit of a pain because of the pretty week main - tail ratio.
TDR 700... using 2s in parallel I got 900rpm max. I don't now how long you can fly because I always stopped after 10min. Using symmetrical 710mm Radix performance on pitch was a bit week which means you had to know what you want before you give stick inputs. Using the Vbar gov I later on tried from 1000 to 2000 rpm. At 1000rpm I had some vibrations because hard dampers. Beginning at 1200rpm you can fly pretty much everything, 1400rpm gives nice performance on pitch with symetrical blades and with a light setup you'll be able to get great 3D performance without wasting energy, high current or low flight time.
Just to compare... flying smack style at 1900rpm no matter if it's a TDR or my e720 12s 4450mAh TPs are empty after 2,5 to 3min.
If you want some more real world measurements at different headspeeds, have a look at Jan Henseleits opinion in his TDR manual -> http://www.henseleit-helicopters.de/Handbuecher/TDR-manual-2011.pdf
As a conclusion... my advice is set the Goblin for a head-speed around 1600 max at 80% on a Jive with 10s, keep your machine light and you'll have lot's of fun. If you get vibrations at certain rpms, just increase / decrease rpm a little bit or try to play with dampers tension. Every model has this, most European / German models at lower rpms, others like Trex at higher rpms.
-Klaus

pitchandyaw
01-28-2012, 04:05 PM
Thanks Klaus. I think I'm going to give this a go. I love my logo at low head speeds and don't see any reason why the goblin shouldn't behave similarly.

worldofmaya
01-28-2012, 05:16 PM
Only question is the head dampening... if they really developed it for hard-3D it may be too hard. Wouldn't be a problem at all to solve that.
-klaus

pitchandyaw
02-03-2012, 11:26 AM
SAB have listed 10s as an option in the manual. I goes that means it has been testing with acceptable results?

TomC
02-03-2012, 06:42 PM
I think that with the supplied stock 22t motor pulley if you select a good 520-530KV heli motor and use a esc with a decent gov, the heli should be pretty happy gov'd to ~1750 hs w/10s and ~2100 hs w/12s. Seems to me you would then have the best of both worlds. Also, 1750 hs is probably high enough, with stock dampers (and 1-shim only), to keep you out of the wobble-zone and the stock tail gear should still hold the tail ok.

Personally, I would avoid using motors with less than ~480kv on 10s because most outrunner motors do not produce good power until they are spinning ~20.000 rpm, which they do with a 520-530kv motor on 10s. On 12s this motor would spin a ittle less than 24,000 max, making very good power without going over design limits (~25,000 rpm is fine for most).

Cheers,
TomC

Joe Bailey
02-11-2012, 07:23 PM
I would be very intrested in seeing one of these at 1500rpm like a TDR, we have two tdr's at my club now both flying at low rpm and to be honest anything more then 1600 on a 90 now just looks like such an effort to get a heli to fly.

Joe