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HomeAircraftHelicopterMain Discussion › Hey what's phase angle?
04-11-2010 04:23 AM  8 years agoPost 1
3kidzheli

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columbia, ms usa

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Can I get a definition of this term and how do I adjust it? Read some post earlier and am cusious if this affects me on something I got going on???

There is no such thing as up, it's all out...

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04-11-2010 05:00 AM  8 years agoPost 2
dkshema

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Cedar Rapids, IA

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The bottom half of the swashplate does not turn, yet it has to pass control inputs to the head. The upper half of the swashplate usually has four balls on it. Two go the the washout base, two go up to the head, usually to the ends of the bell-hiller mixing levers.

The upper half of the swashplate is usually driven by a pair of steel pins that rotate with the main rotor mast. The washout base slides up and down on the main rotor mast, and has a couple of holes or grooves that the driving pins fit into.

The location of those two pins that drive the washout base/top half of the swashplate are what control the phase angle, or phasing.

In many helicopter kits (all of the Trex series, for example) those two pins are permanently attached to the main rotor hub, are in a fixed position, and the phasing is not adjustable. You have to trust that the designer and manufacturer put them in the correct place, or you will end up with aileron/elevator interaction that can only be corrected by using electronic mixing in the transmitter.

Some helicopters (Kyosho Caliber series, Hirobo EVO and Hirobo Freya, for example) have adjustable phasing. The two pins that drive the washout base and upper half of the swashplate are not fixed in the head block, rather they are part of a separate ring (radius block) that is installed on the main rotor mast during assembly.

The picture below is that of a Kyosho Caliber 30 main rotor head. You can see the two washout driving pins embedded in the washout base, and pointing upwards.

Between the base of the main rotor hub and the top of the washout base, you will see a black plastic collar with a couple of grooves in which the washout drive pins slide up and down.

That is the radius block, and if you loosen the two bolts that hold it in place, the block can rotate around the main mast, and when it does, the washout base and upper half of the swashplate move with it. During assembly, that block has to be rotated and fixed in the correct position or the heli will not be controllable, and if it is, there will be a great deal of aileron/elevator interaction.

Phasing is NOT related to the problem you posted in a separate thread, that of one of your three swashplate control servos moving at a different rate than the other two.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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04-11-2010 05:30 AM  8 years agoPost 3
3kidzheli

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columbia, ms usa

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Thanks that helps alot and yeah I was curious a bout the other thread interacting with this as a solution, I tend to think it may be servos getting old, didn't do this when they were newer. What indicaytion would there be is phase angle was an issue? I have a k3d and a pred gasser...

There is no such thing as up, it's all out...

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04-11-2010 05:42 AM  8 years agoPost 4
rotormonkey

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Ottawa, ON - Canada

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On a heli, when you give forward cyclic, the pitch of the blade left of the heli decreases, and the one on the right increases pitch (assuming a clockwise turning rotor). Intuitively you would think that would make the heli pitch left, but due to gyroscopic procession, everything happens 90 degrees.

Well it's not always exactly 90 degrees. Depending on blades, some will lead/lag more than others. Because of that lead/lag, the phasing might be thrown off a bit. So while the rotor head itself is correctly adjusting for 90 degrees, the blades might be at 92 degrees thus throwing off your phasing.

What are the symptoms of incorrect phasing? If you do elevator flips, and the tail appears to be going out of line. Or if you're doing rolls, and they sort of corkscrew a bit as if you were giving an elevator input at the same time when you're not. Those are symptoms of phasing issues. Unfortunately they're also symptoms of ccpm interaction and bad piloting. Hard to tell which sometimes.

Basically when you give elevator you'll get a little aileron too, or when you give aileron, you'll get a little elevator input at the same time. The amount you get might be quite subtle depending on how much the phasing is off.

Don't know if I explained what it actually is well or not.. I tried

If it can't hover, it ain't worth flying.

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04-11-2010 06:14 AM  8 years agoPost 5
dkshema

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Cedar Rapids, IA

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If your heli has adjustable phasing...

Turn the head so that the flybar is perpendicular to the sides of the heli. Hold the flybar level and still so it doesn't flop up and down when you move the sticks.

Move the AILERON stick side to side. If the phasing is set up correctly, the flybar paddles will not move. If the phasing is a bit off, the paddles will tilt just a bit.

Properly adjusted, aileron cyclic should NOT affect the paddles when you have the head in the position described above.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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04-11-2010 06:54 AM  8 years agoPost 6
3kidzheli

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columbia, ms usa

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Great I got it thanks fellas!!!

There is no such thing as up, it's all out...

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04-12-2010 01:26 PM  8 years agoPost 7
TachyonDriver

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Chipping, Lancs, UK

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Thanks from me too! I was aware of the phasing term, but not how to check it on a heli

Tach.

Little Spinning Bundle of Joy® DON'T DISS THE DINO!!

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04-12-2010 02:04 PM  8 years agoPost 8
Frank Bostwick

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Cincinnati Ohio

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Another concise, worthwhile explanation from dkshema on a 202 or even 303 subject.
Thank you

RIP ROMAN

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04-12-2010 02:25 PM  8 years agoPost 9
T Koffler

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Cayuga, NY 13034

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I wonder why a company would design a head without adjustable phasing without it being dead on? It there a reason they would design it with the phasing being out?

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04-12-2010 02:27 PM  8 years agoPost 10
Rotowerkz

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Windham, NH

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This is interesting. I've been the proud owner of a Century Falcon for some time, and noticed recently that they redesigned the head block so that it was not integral with the block that held the pins (radius block)? Previously, the head block and washout pins were purchased as a single assembly, so there was no freedom for setting the phase angle. Since the Falcon shares many parts with the Raven and Hawk (and perhaps the NX50), I think this was the reason for the redesign - to give the experienced pilot the freedom to play with the phase angle.

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04-12-2010 02:34 PM  8 years agoPost 11
T Koffler

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Cayuga, NY 13034

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I remember years ago I had a PHI (tornado or hurricane, can't remember) and when I built it I didnt pay any attention to that block. I just slapped it all together. Well the first time I flew it, it was a handfull! I had it in FFF going into a loop and when I pulled up it went to the right! I think I did track the problem down to that block, eyeballed it up and she was good to go..

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04-12-2010 02:52 PM  8 years agoPost 12
rotormonkey

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Ottawa, ON - Canada

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I wonder why a company would design a head without adjustable phasing without it being dead on? It there a reason they would design it with the phasing being out?
I don't think it's possible to have it non adjustable and have it "dead on" 100% of the time. Because different blades will lead/lag at different angles, phasing depends to some extent on the blades used.

Why would they make it non-adjustable? I would expect for the sake of simplicity. Designs like Align are geared toward the masses. There's a lot of newbies out there that have no idea what phasing is, and are happy not to care. It's one more thing to adjust that isn't completely necessary to get the thing flying.

If your phasing is off it can be corrected with programmable mixing in your transmitter as well so align owners are not completely forgotten

If it can't hover, it ain't worth flying.

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04-12-2010 03:09 PM  8 years agoPost 13
GyroFreak

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Orlando Florida ...28N 81W

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Thanks, a lot of good info here.

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

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04-12-2010 03:16 PM  8 years agoPost 14
T Koffler

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Cayuga, NY 13034

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I don't think any of my MA helis ever had adjustable phasing.. I would think that would be a heli line geared more for the experienced flyer.. I had a Freya that had an adjustable block if I remember right.. I really wonder what the reason is. Probably simplicity? Who knows...

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04-12-2010 10:43 PM  8 years agoPost 15
zaw

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Lebanon, NH - USA

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Is that why my little Honey Bee King goes to the slight right when I do Forward. My Gaui 425 also do that but very slightly.

ಠ_ಠ HBK2 built with inexpensive parts! ٩๏̯͡๏)۶ Gaui425

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04-13-2010 12:56 AM  8 years agoPost 16
Rotowerkz

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Windham, NH

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On smaller helis, the linearity of the swashplate as the collective goes up and down is more critical. Yes, you might have a flat swash low, middle and high stick, but when you change the collective quickly, one servo may very well lag the others, causing an imbalance, which may also produce the pull left/right. I doubt that lack of a phasing adjustment would preclude you from being able to fix the pulling condition on your HBK.

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04-13-2010 03:21 AM  8 years agoPost 17
max232

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Pensacola

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Great info here. i have a question? could this phasing cause the blades to make a different sound on a flb head? my heli makes a completely different sound than it did with a flybar it seems to fly ok, i am just concerned at the sound. still tweaking the setup. thanks for any input on this.

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04-13-2010 01:26 PM  8 years agoPost 18
rotormonkey

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Ottawa, ON - Canada

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No phasing offset can not make any difference in sound in and of itself. All it does is change when/where the control surfaces move when you give a cyclic input, so it'd be exactly the same as moving your cyclic stick up and right, as opposed to just up for example. No change in sound there.

If you've gone to an FBL head, and noticed the sound change, it's probably due to the missing sound of the flybar whizzing through the air. You wouldn't think it'd make much difference in the way it sounds what with all that other stuff whizzing through the air too - but it does.

If it can't hover, it ain't worth flying.

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