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HomeScale✈️AircraftScale HeliScale Helicopter Main Discussion › 4 Blade Head issues
11-22-2017 03:13 PM  21 months ago
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stephen01505

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Glasgow

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4 Blade Head issues
I have recently fitted a 4 blade head to my Align 700 electric and running a head speed of around 1370 but don`t seem to have great tail authority.
Running an Align G-Pro ,Does anybody have any suggestion,I am new to multi blade heads?

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11-22-2017 03:16 PM  21 months ago
co_rotorhead

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Centennial, CO, USA

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The 2 most common solutions for this are 1) longer tail blades or 2) more tail blades.

Which option you go with will ultimately depend on how "scale" you want the helicopter to look. For example, on my 5-blade 600-size AH-6, I am running a 2-blade tail rotor with 105mm tail blades since the full-scale AH-6 has a 2-blade tail rotor and I am going for authenticity.

On a 700-size heli, you could try 115mm tail blades and see how they hold. (On my 800-size Huey, I am running 800mm main blades and 130mm tail blades with a headspeed about 1300-1350)

Or you could go with a 4-blade tail rotor with standard length blades. Again, it depends on what you're looking for as far as how authentic you want it to look.
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11-22-2017 03:21 PM  21 months ago
ssmith512

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Indianapolis, IN USA

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Also, some research on your part is needed to get the correct Align part numbers, but there are different main gears and tail drive gears that you can install that will increase the tail ratio for a faster spinning tail.Steve
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11-22-2017 06:52 PM  21 months ago
goodhunting

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Slovenia ... somewhere in Europe

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Yes it would help to know which helicopter you are building....
But in general I'm with Steve.... There are gearing options for the tail....

Klem
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11-22-2017 07:30 PM  21 months ago
Grimracer

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Eau Claire WI

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Align just announced a new taller tail ratio for lower head speed gear setup for the 700.

Grim
Michael J Zaborowski
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11-23-2017 12:11 AM  21 months ago
TailKiller

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Panama City, FL

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Everything stated above to true and will serve you well. I have found another way without gear changes and with a slightly larger tail blade.
Most controllers will have you set the tail to zero pitch center.
If you set center to a start point of 4 degrees positive on the tail to start to counter the rotor head torque, Settle on a HS range to fly, say 1300. Put the heli in the air and flip from HH to Rate and then adjust from there till the heli tail holds in Rate mode. This way just a little more pitch from the rudder stick will nose right, a little less pitch will nose left from the torque. And vise versa for CCW. Works great for me and the gyro will not have to work so hard to hold the tail.
,Dennis
http://pcrcheliclub.com/
700 Astar Super Scale T-600 Bell 206 Trex 600 Naza H DX8
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08-26-2018 11:38 PM  12 months ago
flyawayed

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orlando , fl .USA

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Another question is what size main blades are u running on the head? If they are standard main blades for a 2 bladed pod and boom heli that would be a a big point of ur problem with double the drag of 4 standard blades would make any 4 bladed head hard to hold heading. Alot of time when doing scale you need to go smaller and thinner on the main blades to not over torque the tail when trying to have good heading hold control. All my 4 bladed heads I've built I've used scale blades that can be between 12-20mm thinner, and rule of thumb is with scale u always go smaller when adding more blades.like 3 of my scale 700 size birds I used 600mm /640mm and they were 42mm or 32mm wide,those are thin blade but have loads of lift at speed from 1100-1500hs.edward lopez sanchez
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08-27-2018 09:18 AM  12 months ago
Andy01

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Brisbane, Australia

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stephen01505...
I have recently fitted a 4 blade head to my Align 700 electric and running a head speed of around 1370 but don`t seem to have great tail authority.
Running an Align G-Pro ,Does anybody have any suggestion,I am new to multi blade heads?
It depends on what you are trying to do. If you are flying it in a gentle scale like fashion as a pod and boom, then a couple of things;

1. The headspeed is probably too fast if you are running 4x 700mm blades. I have a 4x 820mm running at 1050rpm with 2x 150mm tail blades, and a 2x 710mm running at 1350rpm with 2x 120mm tail blades. So I would think that 4x 700mm should run around 1200rpm with at least 2x 130mm tail blades. A slower headspeed, of course, makes you problem even worse.

2. If you are running stock 115mm tail blades (2 off) it has no chance. Even with faster gearing you are going to have to longer / wider / asymmetrical / multiple (or any combination of the above) tail blades.

If you trying to fly it quite aggressively then the headspeed might be appropriate but you need even more tail authority.

Also, the not-so-good news is that the tail authority will almost certainly get even worse once you chuck it into a fuselage as the combination of more weight and larger sail area increases the need for tail authority even further.

Colin
Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon )
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08-27-2018 10:58 PM  12 months ago
Heli_Splatter

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USA

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Could someone suggest headspeed and blade size for Trex500 helicopter?
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08-28-2018 09:36 AM  12 months ago
Andy01

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Brisbane, Australia

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How many blades ? Flown scale ?

For a 2x 465mm, try 1700rpm.

Minor hijack.

Colin
Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon )
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