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Old 06-15-2017, 07:03 AM   #1 (permalink)
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Default 700L V2 or 700X Decision

I am trying to decide between the two heli's in kit form. I can get the 700L V2 for a very good price or spend more and get the 700X. Both heli's will be low head speed projects.

What would you fellas recommend?

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Old 06-15-2017, 08:25 AM   #2 (permalink)
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The 700x is lighter. I would think that would be better for LHS.
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Old 06-15-2017, 10:58 AM   #3 (permalink)
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Originally Posted by NC_2_VA View Post
The 700x is lighter. I would think that would be better for LHS.
That is a good point. How much lighter?
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Old 06-15-2017, 01:21 PM   #4 (permalink)
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Actually the all up weight of both helis if built with 'super combo' hardware is about the same. The 700X airframe is a bit lighter but it's motor is a bit heavier, overall it's about a tie. There is roughly 70g difference in the bare mainframes, give or take, so not a big deal really.

I have the 700X and love it and would recommend it to most people but to be honest IMHO neither the 700X or 700L V2 is 100% ideally suited for 'proper' LHS because you have very limited main gear ratio options and no option at all for higher speed tail ratios. You are also limited on tail blade size due to main to tail blade clearance (though the three blade tail is an option). They work great at 'lowish' HS but for seriously LHS adjustable tail ratio would I think be desirable.

The 690SX that you already have is the heli that's probably better suited to LHS... no?
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Old 06-15-2017, 09:44 PM   #5 (permalink)
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Quote:
Originally Posted by Grumpy_Old_Man View Post
Actually the all up weight of both helis if built with 'super combo' hardware is about the same. The 700X airframe is a bit lighter but it's motor is a bit heavier, overall it's about a tie. There is roughly 70g difference in the bare mainframes, give or take, so not a big deal really.

I have the 700X and love it and would recommend it to most people but to be honest IMHO neither the 700X or 700L V2 is 100% ideally suited for 'proper' LHS because you have very limited main gear ratio options and no option at all for higher speed tail ratios. You are also limited on tail blade size due to main to tail blade clearance (though the three blade tail is an option). They work great at 'lowish' HS but for seriously LHS adjustable tail ratio would I think be desirable.

The 690SX that you already have is the heli that's probably better suited to LHS... no?
Thank you for the information Grumpy.

This is a case of wanting to build another heli If I could keep the tail control up with proper gearing, I would be happy turning 1500 or so on the 700x for slowish aerobatics. Maybe a small stretch with a 700N boom coupled with a three bladed tail?


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Old 06-15-2017, 11:32 PM   #6 (permalink)
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Originally Posted by Grumpy_Old_Man View Post
I have the 700X and love it and would recommend it to most people but to be honest IMHO neither the 700X or 700L V2 is 100% ideally suited for 'proper' LHS because you have very limited main gear ratio options and no option at all for higher speed tail ratios
*ahem*

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Old 06-15-2017, 11:37 PM   #7 (permalink)
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Quote:
Originally Posted by Grumpy_Old_Man View Post
I have the 700X and love it and would recommend it to most people but to be honest IMHO neither the 700X or 700L V2 is 100% ideally suited for 'proper' LHS because you have very limited main gear ratio options and no option at all for higher speed tail ratios
*ahem*



Also if you slot the boom mount holes by 1mm you should be able to run the Trex 700N front gear and auto gear which has a 4.95:1 ratio. If the kit comes with the 4.3:1 gears you'll need the older 104t auto gear as well.
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Old 06-15-2017, 11:52 PM   #8 (permalink)
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Originally Posted by Atomic Skull View Post
*ahem*



Also if you slot the boom mount holes by 1mm you should be able to run the Trex 700N front gear and auto gear which has a 4.95:1 ratio. If the kit comes with the 4.3:1 gears you'll need the older 104t auto gear as well.
I have that exact KDE setup on my 600 and love it!

The only problem is there is no KDE adjustable mount listed under the 700X section...
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Old 06-16-2017, 01:14 AM   #9 (permalink)
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go for 700x . cos if u have 700L.. ur heart wil look at 700x in future. if u have the 700x. u wont bother to look at the L again.. 2 cents anyway
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Old 06-16-2017, 04:25 AM   #10 (permalink)
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The cheapest solution on the tail is probably a slight stretch using the 700N boom then use 115mm tail blades.
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Old 06-16-2017, 05:55 AM   #11 (permalink)
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weeeelllll if money is not an issue then go all the way out...
if you're on a budget then get the cheaper one...

I "had" a T700 V2... stock electronics (all from motor to ESC and servos)... all set up out of the box... for 12S...
At one point I (deliberately) plugged only one battery... so it flew on the 6S setup... quite ok.

I fly scale... not 3D for me... and I set up my helicopters so that I hover (5,5 deg pitch) at mid stick.... this setup required about 3/4 of throttle and it still climbed out ok... If I were to keep it at 6S I would play with this setup to give it some room for the "oh SH*** moments" but other than that it flew fine for the LHS.... Yes one needed to stay ahead of the cyclic inputs and predict what the heli will do but this is the story of the LHS helis in general...

so if you want to fly it at 1500 RPM... I believe you'll be fine with both helicopters...

gh
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Old 06-16-2017, 07:10 AM   #12 (permalink)
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The new 760X might be worth a look if you are interested in LHS. It's more expensive but comes 'pre-stretched' and includes the 3 blade tail.
It comes with the HW 160A ESC which you wouldn't need for LHS but you could easily sell it and replace it with a 130A and offset some more of the difference in cost.
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Old 06-16-2017, 01:57 PM   #13 (permalink)
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After more research and listening to advice from you fellas, I think the 700x is the way to go.

I figure adding the 760 boom with a three bladed tail would offset any tail holding issues at lower head speeds (900 to 1500 rpm is the goal). Maybe KDE will come out with an adjustable motor mount for the 700x

As far as the servos and esc are concerned, I have MKS 960's and a 990 along with a HW 120a V4 and a Menzon 135 opto but I am a little concerned about using the Menzon after hearing about the failures on 12S. To top it off, I love the HW governor.

For F3C flying along with some mild aerobatics, do you guys think the 120a would suffice? I have no problems picking up a HW 160 but only if it is really needed.

Lastly, I am picking up a kit only with no blades, motor, esc etc..

Thanks for the feedback,

Sawacs
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Old 06-16-2017, 02:27 PM   #14 (permalink)
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The HW 120A V4 is 6S only, so no, that's not going to be safe on a 700. The HW 130A HV V4 is fine, that's what the 700X super combo comes with (but Align branded)

If you are getting the bare airframe kit then for LHS you could get a motor with lower Kv, something in the 400Kv ballpark. That would get around the need for adjustable gearing.
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Old 06-16-2017, 02:31 PM   #15 (permalink)
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Quote:
Originally Posted by Grumpy_Old_Man View Post
The HW 120A V4 is 6S only, so no, that's not going to be safe on a 700.

The HW 130A HV V4 is fine, that's what the 700X super combo comes with (but Align branded)
Thanks,

I completely forgot about the 120a being 6s only.. doh!

Looks like there will be a 130a HV V4 heading this way
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Old 06-21-2017, 05:02 PM   #16 (permalink)
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From what I can tell, there is no way to change the motor pinion gearing on the Trex 700x since there is no way to adjust the motor mount correct?

However, with the 700 V2, I could pick up an adjustable mount which would provide an option for different pinions for use with different head speeds.

This is the one and only aspect of the 700X that keeps me from pulling the trigger

Cheers
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Old 06-21-2017, 10:55 PM   #17 (permalink)
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you can get 112T with 12T pinion.. i am using it now for my 700x.. rpm about 2000 at 83% gov v4 esc.

i guess u can push down to 75% ... to get lower headspeed.. i do harder 3d now..so i need 2000rpm.
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Old 06-22-2017, 02:34 AM   #18 (permalink)
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OR!!!!
you could change the ESC... get the Kontronik heli Jive 120HV and you can play with the free-wheeling function of the ESC and reduce the HS without changing the gear ratio...

gh
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Old 06-22-2017, 03:22 AM   #19 (permalink)
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No issues with Castle 160HV on my 700L as low as 1600-1700rpm in hard flying. It never gets more than warm.
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Old 06-22-2017, 05:45 AM   #20 (permalink)
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OR!!!!
you could change the ESC... get the Kontronik heli Jive 120HV and you can play with the free-wheeling function of the ESC and reduce the HS without changing the gear ratio...

gh
You don't need to change the ESC. The 700X or 700L V2 'Super combo' both come with Hobbywing V4 ESC's that already have active freewheeling (just like Kontronik, but cheaper!)

Having said that, running low RPM by governing down isn't as efficient as optimising the gearing, active freewheel or no.
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