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HelicopterCentury Radikal G20-30 N640 Hawk Predator › what yeeaa think, 640 RTs on a 50,,
01-04-2010 04:01 AM  7 years agoPost 1
Gearhead

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well for years I wanted to try longer Blades on my Century 50s,, longer Blades more Lift, and larger Disk, larger Disk smoother heli, and I like smooooth

here's my thoughts,,
so with 600s and 620s size Blades guys are running 12 and 13 Degrees of Positive Collective on their Ravens & NX50s ,, well how about using less Pitch with the new RT 640s,,

the set up would be,,
use the older Stock 55t Counter Gear to get an Engine Speed of 17,500 for a Head Speed of 1930 (yes I did the calculating), and use a Collective Pitch around 10 Degrees,,

yes a longer Boom/T-Tube would be needed but for myself I see no real problem there making that up,, hummmm, I wonder if the Predator Boom and T-Tube would work (I got to look into that now)

what-cha think ??

Jim
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01-04-2010 04:37 AM  7 years agoPost 2
MAXHSHV

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i bought a predator boom and tourqe tube to strech a raven and then the big block i had in grenaded but now you have me thinking.

Century heli rep. To much power is never enough.

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01-04-2010 03:35 PM  7 years agoPost 3
Dilbeck

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Springdale Arkansas

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I have a set of Century 640 wood blades on my Raven right now. Just got them to try out before I did anything futher. I like them even with the current gearing and engine. The extra lift at lower head speeds is very noticeable. They are only $26 so I figured what the heck Im only sport flying anyway.

I didnt think the Predator boom would fit the Raven, will it??

Clint

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01-04-2010 10:37 PM  7 years agoPost 4
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Dilbeck,, I first have to ask you, with your 640 Woodys what size Tail Blades are you using and how close do the Mains come to the Tails ??

as for the Predators Boom I know it's Diameter is 21mms, so last night I measured the 50s Diameter and I got 20mms, but my Plastic Calipers seam to have a bit of slop in them so I think the 50's are 21 also,, (I need to buy new Calipers, also I dropped and broke my SS Calipers eerrrr),,, plus there was a photo on here of a guy having the Predators Metal Tail Box on his Raven (I think BM bought that heli),,, so we would have to shorten the Predators Boom, I measured the 50s Boom Length and the Predators is some 5 inches longer,, we only need a Boom 1& 3/4 inches longer for 640s IF you want to run 92mm or 95mm Tail Blades,,

as for Collective Pitch with the OS Hyper 50 I was thinking even if we had to run 9 Degrees of Collective that should be OK too, the Longer and Wider RT 640 Blades will have more bite in the Air, and the Cyclic would still be crisp with a HS of 1930,, and of-course a good Governor will help below Full Throttle,,

now with the new Larger 55,56, 57 and the new KME 60 you may get away using the Gray 53t Speed-up Gear,, with the Gray Speed-up Gear at a Ratio of 8.736 and an Engine Speed of 17,500 we would have a HS of 2003,,

it seems for all out power the KME 60 is the way to go !!

Dilbeck,, one other thing, those New RT 604s are about 4mm wider than the Woodys, so you will need more power there for that..

you see, this is another raison why I like Century 50s, they are so versatile !!

Jim
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01-04-2010 11:48 PM  7 years agoPost 5
Dilbeck

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Springdale Arkansas

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Dilbeck,, I first have to ask you, with your 640 Woodys what size Tail Blades are you using and how close do the Mains come to the Tails ??
The 640 main blades are hanging over the stock tail blades by 1" max. I did notice a slight drift that started to develop with the addition of the longer blades. These Century 640s are 58mm wide at the tip. Not sure of the RT. I am currently running a +10/-10 pitch with the OS50 hyper. I truly believe with this combo of blades and engine I will not need a governor for the engine is at its sweet spot. I noticed no bogging what so ever with this pitch range on a power climb out. Though Im using a Align governor it didnt seem to matter at 2000 head speed. Further test will be needed to confirm this.

Clint

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01-04-2010 11:49 PM  7 years agoPost 6
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edited,,

ok ok I did more measuring after my supper, it doesn't take long to eat supper when you know you got to do something on your heli LOL

wow I'm surprised , I have 95mm Tail blades on my Raven and I found 640s will fit without hitting the Tail Blades,, COOL !!,,, with the 95mm T-Blades I would have a good 1&1/2 inches between the 640 Mains and 95mm Tails,,

so it can be done,, but ideally a Boom 1 or 2 inches longer would be best,,

and to add to the whole thing the longer 640 will create more Counter Torque on the Air Frame giving you a bit less power (Nose right) on the Tail, but I could live with that, a longer Boom would help a bit there too..

this hobby is so cool yet so expensive, I have 2 Gasser Planes and a Glow Plane to get in the Air this Spring, and I want a Radikal too, and now I want to do this with the 640s with a KME 60 LOL, and I want to convert my Raven to a NX,, LOL I don't think it will all happen this spring

Jim
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01-04-2010 11:52 PM  7 years agoPost 7
Gearhead

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""The 640 main blades are hanging over the stock tail blades by 1" max""

humm, are you sure you don't have the 30 Boom on you heli ??

I will measure again,, hold on..

Jim
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01-05-2010 12:07 AM  7 years agoPost 8
Gearhead

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I did MORE measuring,,

this time I turned the Tail so the T-Blades were pointing at the Main Blades,, if the 640s Mains bent a bit in flight as we know they do I will have about 1 inch between the 2 Blades, even if I had a Boom Strike I don't believe the blades would hit,, but still, a longer Boom would be best,, and a longer Boom could be made with the Predators Boom and T-Tube..

Jim
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01-05-2010 12:19 AM  7 years agoPost 9
Dilbeck

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Springdale Arkansas

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I was off a little, Its a 1/2" overlap with the 640 mains and the Raven stock tail blades. Im not the least bit worried about that because Iv yet to make contact with any helis main blades and tail to date. Ive run 600s on the stock Hawk Pro many a time with no problems. Maybe because I fly them like I paid for them instead of Flying them like I stole them!! I would be interested in experiencing with a longer boom if it would fit though!

Clint

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01-05-2010 12:46 AM  7 years agoPost 10
Gearhead

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the thing is, 40mms is a bit less than 1&5/8 inches,, so just mounting the 5 inche longer Predator Boom/T-Tube as-is on a Raven or NX is a bit over kill..

Clint,, do something for me,, measure from the Back Edge of your Frame where your Boom goes into, to the Edge of your Tail Gear Box, and post the results ,I will do the same, I'm thinking you have the 30 size Boom on your Raven..

Jim
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01-05-2010 12:53 AM  7 years agoPost 11
Gearhead

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measuring from the Back Edge of my Frame to where my Boom goes into the Edge of my Tail Gear Box,,

(measuring on the top of the Boom) I'm right at 24& 5/8 inches..

if your shorter than that then you probable have the 30 Boom in your Raven

Jim
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01-05-2010 01:04 AM  7 years agoPost 12
Dilbeck

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Springdale Arkansas

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I got the same measurement + 1/16. I purchased this Raven stock and could not imagen them sending a 30 tail boom in the kit. But anything is possible.

Clint

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01-05-2010 01:09 AM  7 years agoPost 13
Dilbeck

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Springdale Arkansas

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Did some more poking around and found a 30 boom from the Hawk, It is way shorter than the Raven. Matter of fact I dont have anything Hawk or otherwise using the 30 size boom. Its all 50 now..

Clint

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01-05-2010 01:14 AM  7 years agoPost 14
oldfart

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Vancouver, Canada

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The key to most any such enlarging of any heli, from the size it was designed for is what Clint said here:
Maybe because I fly them like I paid for them instead of Flying them like I stole them!!:
Which means, that it all depends on the type of flying you plan to do with it.

Set for a high rotor head speed, using 640mm blades and a 56/60 engine, just maybe something it the power train (e.g inner teeth of the maingear) or rotor head (e.g 6mm spindle), may not be designed to take the forces that they will be subjected too, in more demanding 3D flying.

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01-05-2010 02:01 AM  7 years agoPost 15
crash n' burn99

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ottawa, canada

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Im going to 640's on the radical just for better autorotation.

Do proctologists chew there finger nails when there nervouse?

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01-05-2010 03:15 AM  7 years agoPost 16
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well I hear that Phil,, it's just so tempting to try, and all the parts are there to do it/try it LOL

think about this, flying RC helis is like being a Doctor, it's a practice LOL, you fix it or try something new and off it goes, but it may come back to be fixed again LOL

Jim
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