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HomeAircraftHelicopterMain Discussion › my heli leans to one side why
01-12-2009 06:52 PM  9 years agoPost 21
jgunpilot

rrKey Veteran

Pollock, LA

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Check your setup

Sounds to me like you have a swash plate leveling error somewhere that is making it up through the paddles and into the main blades. You need to make sure that you swash is completly level with zero deadband (no trim, 50 in 50 out in stunt mode, with hold off)
Does your heli hover with the rotor system level with the horizon, skids level, and it doesn't slide to the left? Maybe I need to go back and check my setup, too. Mine always hover right skid low. All three of them.

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01-12-2009 06:56 PM  9 years agoPost 22
BarracudaHockey

rrMaster

Jacksonville FL

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Check your setup

Sounds to me like you have a swash plate leveling error somewhere that is making it up through the paddles and into the main blades. You need to make sure that you swash is completly level with zero deadband (no trim, 50 in 50 out in stunt mode, with hold off)
So you're pretty much saying all of the above responses are incorrect?

Andy
AMA 77227
http://www.jaxrc.com

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01-12-2009 07:29 PM  9 years agoPost 23
dkshema

rrMaster

Cedar Rapids, IA

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Check your setup

Sounds to me like you have a swash plate leveling error somewhere that is making it up through the paddles and into the main blades. You need to make sure that you swash is completly level with zero deadband (no trim, 50 in 50 out in stunt mode, with hold off)
So you're pretty much saying all of the above responses are incorrect?
'Cuda -- some people are simply able to suspend the laws of physics to suit their own needs. After all, a level swash and zero degrees pitch at mid stick cures all.

-----
Dave

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

Team Heliproz

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01-12-2009 08:31 PM  9 years agoPost 24
jgunpilot

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Pollock, LA

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Roger that!

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01-13-2009 03:58 PM  9 years agoPost 25
T-Rex-Flyer

rrElite Veteran

Panama City, Fl

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i have a t-rex 600n and when in hove it seems it wants to lean to the right if your looking at it from the tail faceing you why would this be?
Bottom line, it's normal

As to why, listen to Professor's dkshema, and BarracudaHockey they'll never steer you wrong.

If the wings are traveling faster than the fuselage, it's probably a helicopter.

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01-13-2009 04:08 PM  9 years agoPost 26
jschenck

rrProfessor

La Vista, NE.

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A more simplistic view of this is to imagine your heli sitting on a bench (air hockey table) then attach an electric airplane to the tail boom running full throttle. it'll tend to pull the heli around in circles. if you had someone holding the nose to keep it from spinning it'll get pulled straight sideways.

Simple experiment - try disconnecting the main motor from your Blade CP and run the tail motor up to speed. It's surprising how much thrust that creates. Imagine how much is being created by the larger heli's. That's why the heli tends to get pushed to the side.

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01-13-2009 05:58 PM  9 years agoPost 27
axemanclint

rrKey Veteran

Cypress, Tx. USA

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Translating tendency, the tendency of the helicopter to slide to the left has to be corrected with a bit of right cyclic. This is caused by the tail rotor (on a right hand rotation main rotor) blowing the helicopter sideways.
Exactly what Barracuda said,
This is translating Tendency, all helicopters deal with this in some form or another especially full scale. Unless you are flying a Dual Counter rotating main blade helicopter this will happen. Totally normal and you will get used to it.

Its also why if you ever notice when you lift off the ground into a hover you need to add some right cyclic just a little bit to maintain a Stable straight up hover without wondering.

"what goes up must come down," hopefully in one piece!

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01-16-2009 12:54 AM  9 years agoPost 28
wthford

rrVeteran

Monticello, Illinois

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I know we don't want to say the dreaded "P" word here... but planks have the same problem. Check the firewall on them... They are not straight. They are slightly offset to make up for the same phenomenon. I believe it to the right to make up for the clockwise rotation of the motor. I'd have to go and look at one of mine, but they're out in the cold right now... (yes, I have a few planks)

Stinkin' physics!

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01-16-2009 01:40 AM  9 years agoPost 29
dkshema

rrMaster

Cedar Rapids, IA

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Planks have the offset and down thrust for completely different reasons...torque and P-factor, not translating tendency due to a force being generated by a second propellor mounted 90 degrees to the main thrust line.

P-factor is asymmetric thrust from the propellor blades caused by the difference in the blade's relative angle of attack...

From a website I found using a quick search for "P-factor":
P-Factor is an aerodynamic effect that causes propellor-driven planes to yaw when they are flown at high power and low speed (takeoff and climb out, for example.)

At low speeds, the plane flies at a substantial angle of attack, and so the airflow is not parallel to the plane's axis. Relative to the plane, the airflow is directed several degrees upwards. Now the prop axis is normally parallel to the plane's axis. As the prop rotates, on one side the blades are traveling upwards and on the other side they are traveling downwards. (On most planes, the prop turns clockwise, as seen from behind, so the left side goes up and the right side goes down.)

The upwards angle of the airflow causes the downward (right) side of the prop to have a greater airspeed and angle of attack than the upward (left) side. So the downward (right) side of the prop generates more thrust. Pull harder on the right side of the plane than on the left and the plane will yaw to the left.

This is one of the reasons why most real prop planes need a certain amount of right rudder to keep them straight during takeoff and climb out.

The other factor that requires right rudder on takeoff (in planes with clockwise props) is spiral propwash. The sideways component of the spiral propwash strikes the vertical stabilizer from the left (in conventional single engine configurations), also causing a yaw to the left. In general, the spiral propwash effect is a lot stronger than P-factor.

You also need right aileron to keep the plane straight to counteract the rotational torque from the engine(s).

-----
Dave

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

Team Heliproz

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01-16-2009 01:44 AM  9 years agoPost 30
#55

rrVeteran

Dyersburg, TN

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correct^^^....

there is NO translating tendency in Planks Guys, If ya don't know what your talking about--- DONT post it....

Dropping Tones!

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01-16-2009 01:47 AM  9 years agoPost 31
jschenck

rrProfessor

La Vista, NE.

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That was my thought - the offset firewall on the airplane is there essentially for the same reason we put tail blades on the heli. That's different than the side lean that we need on a heli to compensate for the thrust of the tail. Now if I remember the Cherokee I solo'd in (almost 20 years ago !? N41497) had the left wing slightly higher than the right wing to help compensate for the torque also.

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01-16-2009 01:53 AM  9 years agoPost 32
AirWolfRC

rrProfessor

42½ N, 83½ W

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Now if I remember the Cherokee I solo'd in (almost 20 years ago !? N41497) had the left wing slightly higher than the right wing to help compensate for the torque also.
Nope, - you just had a right strut lower than the left.

Thrust is compensated for by some right thrust in the engine mount and/or about 1º or so of built in right vertical stabilizer.

Note - the P51D also had 1º of vertical stabilizer offset.

Down thrust in the engine mount is to compensate for the tendancy of a wing to "nose up" when the airspeed increases (flying faster with engine forward thrust and having an asymetric airfoil).

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01-16-2009 07:48 AM  9 years agoPost 33
greenking

rrNovice

Sydney, Australia

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Here's what's going on.......
Guys,

I wrote the attached documents to answer the same questions on another website. I think it makes it all reasonably clear - as long as they are attached!!

Regards

GK

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01-16-2009 09:18 PM  9 years agoPost 34
Richard Morgan

rrApprentice

Virginia Beach, Virginia USA

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On the level....
First, place the Heli on a level surface with the nose facing you. Then take a bit of twine and tie it to the skid that is always low in the hover. Next, throw the other end of the twine over the top of the canopy and tie that end securely to the skid that is always higher. This should keep things level in the hover, and then you can always make fine adjustments to the Heli to be by simplely varing the tension. Oh, be sure you don't get the twine tangled in the swash plate or mixing arms.

Kinda unsightly, but this just might work!

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01-17-2009 12:47 AM  9 years agoPost 35
M S Robinson

rrNovice

UK

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Out of curiosity what full size helis have a offset main rotor in a lateral direction? The ones I work on only have a forward tilt to level the fuselage when the aircraft is in a cruise. On a Lynx this is 4 degrees.

At a higher speed the tail fin provides the a lot of the force counteracting the torque from the main rotor. There is hardly any tilt required because it is an aerofoil reacting to the forward airspeed rather than the rotor blowing the air sideways. On a Gazelle it comes into effect at around 60kts.

I'm not sure if I explained that very well.

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01-17-2009 01:01 AM  9 years agoPost 36
AirWolfRC

rrProfessor

42½ N, 83½ W

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You explained it fine . . . .
. . . . but we're talking about in a hover where you see the tilt.

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01-17-2009 01:39 AM  9 years agoPost 37
dkshema

rrMaster

Cedar Rapids, IA

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The vertical fin won't do much in a full scale heli to stop translating tendency in a hover. It might be big and all air-foily and stuff, but in a hover, it's incapable of providing any lateral force on the airframe.

-----
Dave

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

Team Heliproz

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01-17-2009 01:41 AM  9 years agoPost 38
Yug

rrMaster

UK. Herts

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i have a t-rex 600n and when in hove it seems it wants to lean to the right if your looking at it from the tail faceing you why would this be?
Consider the fact that the TR is working to correct the torque of the mains, then it follows that the heli will lean to the right. This is basic stuff. At all times you are 'flying' a heli if you see what I mean.

Vegetable rights and Peace

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01-17-2009 03:16 AM  9 years agoPost 39
billm

rrElite Veteran

Liberty Lake, WA

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YUG, Nice to see you back. The last photo of you was drinking out of a Nitro Bottle. Now that will make you lean to the left.

My name is Billm. Cough, and I'm a Heli Holic

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HomeAircraftHelicopterMain Discussion › my heli leans to one side why
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