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01-08-2013 02:03 AM  7 years ago
Chris.C

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Hong Kong

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With 3 blade head, we achieve lower head speed by a smaller pinion, e.g. in standard e-caliber, the pinion is 24T so with 3 blades head, we use 23 or 22T.

The JR MB351 head is for their 8 cells helicopters, e.g. NEX E8, spinning 600mm blades.
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01-08-2013 02:17 AM  7 years ago
rapidity

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ohio

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Can u get the same amount of forward energy running a 3 bladed head at lesser rpms than a 2 bladed head at the higher rpms like we do now?
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01-08-2013 04:22 AM  7 years ago
Santiago P

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Dayton

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Hey rapidity

If you were to try spin three 700mm blades to the ussual 2000 rpm you will need 50 more energy to due so, meaning 50% higher amps and a bigger battery to make the time due to the higher rotational inertia and parasite drag.

The fwd speed is a product of pitch and rpm. Lower RPMs means you need a little more pitch to reach your desired 90-100mph, (I seen you like to haul arce)

With 9 degrees at 1950rpm (2 blades) I got enought to make any manuever too big, or to instantly stretch or accelerate through the dreaded loop with double stall turns.

With a 3 bladed head, I would think 1800 at 11 degrees would give me similar fwd speed.
Also no draggy flybar to slow you down.
Team Minicopter - PeakAircraft.com
FUTABA.USA - Team Kontronik - Scorpion Motors-
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01-08-2013 06:05 AM  7 years ago
Chris.C

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Hong Kong

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Also you will few better in an autorotation.
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01-08-2013 12:13 PM  7 years ago
rapidity

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ohio

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K&S has one also. Fits 10 or 12mm shafts. Different from the JR as it doesn't have the direct connection to the swash. Funtech has some 720 and 790mm blade sets available for it. Doesn't have any parts listings for it, may be to new. Around $430. It's a 90 size head. 12 or 14mm blades.
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01-08-2013 04:44 PM  7 years ago
luixitoyo

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Lausanne - Switzerland

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01-09-2013 01:19 AM  7 years ago
richardf

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San Diego, CA USA

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I ran the K&S link through a Japanese to English translator
Page 1
<KS-FBL 90-3Toriatsukaisetsumei-sho>
We seek to purchase this product, Thank you very much.
Please use the above to read the instructions, and you understand product performance.
<Features>
90 ~ GS class is dedicated FBL (Flybarless) head.
Buoyancy margin occurs because three rotor to share the load.
Airframe vibration not only reduced, allowing accurate flight.
Can be mounted on the fuselage of 12 mm and 10 mm diameter mast.
The parts that are designed for rugged, it is available from machine to machine weight F3C.
We have adopted the structure slotted scissor arm and body so that the head can be attached to the mast exactly.
Enjoy great flight performance of three FBL head.
<> Usage Notes
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01-10-2013 12:48 AM  7 years ago
richardf

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San Diego, CA USA

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Testing at 1300 - next one at 1250

Watch at YouTube

A not so good video of 1300 RPM test hop in the backyard, will replace it soon.

-Richard.
AMA 4628
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01-10-2013 01:21 AM  7 years ago
rapidity

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ohio

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So whats the gear ratio, motor, fbl controller, esc?

Which radix blades are u running, wt?
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01-10-2013 02:45 AM  7 years ago
richardf

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San Diego, CA USA

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Gear ratio is 93/11 or 8.45, Scorpion HK-4530-400Kv, Spektrum AR7200BX integrated BeastX with light 180 Radix blades for testing. Have Radix that weigh 210 in reserve after I test a little more.

-Richard
AMA 4628
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01-11-2013 01:45 AM  7 years ago
Dr.Ben

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Richmond, VA, USA

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Guys,

In all of the discussion about drag comparisons and so forth, there is another major factor that is a driving force in the recent use of 3 bladed heads on FAI models. With a FB model, bell hiller mixing effectively creates a steering component to the system every 90 degrees. FBL two bladed systems use hiller only control, so assuming a pure cyclic input, the control input occurs fully only every 180 degrees. Now we all know that there is no lack of control authority in a FBL model, but by adding that third blade, you also decrease the functional latency of the overall FBL control loop as it relates to the initial command of the FBL controller and the time it takes for the swash input to affect movement in the model. The quicker the model actually responds to the command of the stabilization system, the greater the stability. This is critically important for FAI in which we are seeing the transition from FB rotor heads which effectively react to outside influences(wind) as they are happening versus FBL stabilization which even in its most sophisticated iterations are reaction systems.

Ben Minor
Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA
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01-11-2013 02:00 AM  7 years ago
Santiago P

rrProfessor

Dayton

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Amen to that.

I said the same thing in diferent words on my 1st post
Now this 3 bladed head is making me very curious. I can now see how one can achieve lower headspeeds silky behavior without compromising the control per rev for the FBL unit... hummm

very high rpms (~2000) would not be needed becasue the responce and stability from the 3rd blade.
Before you know it, you'll see 4 blades.
Don't think anyone knows the sweetspot yest. Many combinationsto be tried: # of blades, Dia, RPM, and total disk inertia.

It will be very interesting to see what kind of Rotor systems develop from this.

Santiago
Team Minicopter - PeakAircraft.com
FUTABA.USA - Team Kontronik - Scorpion Motors-
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01-11-2013 03:05 AM  7 years ago
richardf

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San Diego, CA USA

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I did an 8 blade head with standard 690 blades four years ago and you will find a picture in my gallery.

This is too just many blades, the swash plate is seething with balls, plus the follower. You should have heard that sound, wicked, but the issues of trying to setup a flybarless system for me back then was beyond my attention span.

So I can honestly say where the upper limit is.

-Richard.
AMA 4628
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01-11-2013 04:57 AM  7 years ago
Dr.Ben

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Richmond, VA, USA

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Addendum......

Cool factor counts. Three bladed head running like a silent sewing machine on a full fuselage electric FAI model is just plain long cool.

Ben Minor
Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA
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01-11-2013 05:05 AM  7 years ago
richardf

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San Diego, CA USA

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I have a CompTIA Linux LXO-102 test in the morning and if the weather is calmer than (storm) what we have now, I will reset the CC-HV80 to 1200 RPM for a super low hover and see what happens.

-Richard.
AMA 4628
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01-11-2013 11:47 AM  7 years ago
rapidity

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ohio

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Gotta be cool!

So much for the guys who use to say that fbl would make our corner of the hobby a lot more accessible because u wouldn't need an all out competition machine any longer.
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01-11-2013 12:24 PM  7 years ago
ian694

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United Kingdom

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Hi all,

With all the testing for FAI flybarless and 3 blade heads. What type of blade is being used, flybarless or an FAI blade?

Regards

Ian
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01-11-2013 04:04 PM  7 years ago
richardf

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San Diego, CA USA

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I ordered just a hub and spindles for 80 USD to convert a plastic Freya with no other changes as a test for comparison.AMA 4628
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01-11-2013 06:16 PM  7 years ago
richardf

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San Diego, CA USA

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Ian,

I don't yet know how to answer the question about which blades are necessary with a 3 blade setup. One of the better pilots here with experience can extol the virtues of the appropriate blade for the application. With my "sport" settings on the FBL controller and the minimal flapping with a 3 blade setup, there may be a larger margin for controller sensitivity to blade stiffness and other characteristics.

-Richard
AMA 4628
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01-12-2013 03:31 AM  7 years ago
Dr.Ben

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Richmond, VA, USA

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Based on what I have tested so far with CGY750 firmware evolution, there is no ideal FAI FBL blade right now. Speaking of just two bladed heads for now, the current breed of FAI blades is really too heavy for good FBL performance. They will sit in hover pretty well, but they load up the system a bit too much for quick aerobatics. Remember that we need stability, but the blades cannot dull performance so much that the FBL controller fails to get a response to/from the rotor system quickly enough. I have this vision right now that the ideal FBL blade will be a bit less in total mass but still with CG well outboard and will the chordwise CG well optimized for stabilty so that the blade lags correctly in flight.

Ben Minor
Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA
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