[f-AA] Gyroscopic precession can produce a RIGHT turning tendency
Ryan Lunde
-Ryan
jay curtis
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Dan McCormack
Not really. How big is your prop? How big is the airplane?The mass of the airplane easily resists the tiny force applied by the gyroscopic effect.And -- I think we only refer to "precession" as a change in gyro attitude over time.Dan Mc
Ryan Lunde
In most cases, I think the other left turning tendencies combined with the aircraft's speed and stability will mitigate the right turning tendency of gyroscopic precession, but perhaps in certain aerobatic maneuvers at very low airspeed, it would be more of a factor. All I'm trying to get at is that gyroscopic precession should not be talked of as a left turning tendency except in the proper context.
From: jcu...@execulink.com
To: aer...@westmont.edu
Date: Wed, 16 Feb 2011 13:59:18 -0500
Subject: Re: [f-AA] Gyroscopic precession can produce a RIGHT turning tendency
jay curtis
Ryan Lunde
I believe you are correct in that in most cases, the airplane easily resists gyroscopic effects, but the raising of the tail at low speeds on the ground will cause it to head for the weeds if unmitigated.
According to the Pilot's Handbook of Aeronautical Knowledge:
"Precession is the resultant action, or deflection, of a spinning rotor when a deflecting force is applied to its rim."
-Ryan
To: aer...@westmont.edu
Date: Wed, 16 Feb 2011 14:06:30 -0500
From: cbt...@aol.com
Subject: Re: [f-AA] Gyroscopic precession can produce a RIGHT turning tendency
Thomas DeWinter
However the direction of thought is almost always on high power high AOA. When taking off and with power on stall.
What is almost never talked about is the need to add LEFT rudder when reducing power and lowering the nose. Some of this is gyroscopic precession. Others due to the offset of the engine and tail which are meant to cancel out the slipstream and other effects at cruise power settings. So on take off you add right rudder which is taught. But almost always it is neglected to teach the addition of left rudder when reducing power and/or lowering the nose.
This really hit home for me when I was doing my instrument training. I did it in a C-182 which has decent amount of power. So the reduction of power and lowering the nose at the outer marker on the ILS under the hood you could actually see the skid ball move and the need to stay coordinated. Something that I apparently missed when I was lazily looking outside VFR. But it was enough that you could have the localizer needle all lined up and when I reduced power and lowered the nose it would cause the sensitive localizer to move and that would start the pilot ( ME!) chasing the needle. When I learned that I needed to just add a little bit of LEFT rudder when I made the power and pitch change. I could keep the needles dead nuts on and wouldn't have to start chasing them.
Bottom line is that ANY time the spinning gyro we call a propeller is spinning. When it is acted on by a force gyroscopic precession WILL occur. The only question is how much. Which is a function of mass, the speed of the gyro and the amount of the force applied. So precession will occur with BOTH nose UP OR nose DOWN. It will also occur when yawing left or right. Or any combination in between.
It is definitely noticeable when lifting the tail up on my Chief. Especially at low airspeeds where more rudder needs to be added to counteract it.
From: Ryan Lunde <n85...@hotmail.com>
To: aer...@westmont.edu
Sent: Wed, February 16, 2011 11:04:26 AM
Subject: [f-AA] Gyroscopic precession can produce a RIGHT turning tendency
Ian Harvie
dangerous to turn right close to the ground. It was the Gnome Rotary,
may be there were others.
Ian
On 17/02/2011 6:35 AM, jay curtis wrote:
> I think your bang on ! Some WW1 aircraft I thought had engine
> cylinders that spun around with the prop. I believe this killed many
> in the learning process, as the force we are talking of was very great
> due to that big mass spinning and the results of it being moved caused
> by precession.?
>
> ----- Original Message -----
> *From:* Ryan Lunde <mailto:n85...@hotmail.com>
> *To:* aer...@westmont.edu <mailto:aer...@westmont.edu>
> *Sent:* Wednesday, February 16, 2011 2:07 PM
> *Subject:* Re: [f-AA] Gyroscopic precession can produce a RIGHT
> turning tendency
>
> Also, I believe that gyroscopic precession can lead to a pitching
> motion when yawing. Think again about where the force is applied,
> this time at the sides, and where it will act, at the top and
> bottom of the prop. The "Pilot's Handbook of Aeronautical
> Knowledge" alludes to this, but it doesn't get into great detail.
>
> In most cases, I think the other left turning tendencies combined
> with the aircraft's speed and stability will mitigate the right
> turning tendency of gyroscopic precession, but perhaps in certain
> aerobatic maneuvers at very low airspeed, it would be more of a
> factor. All I'm trying to get at is that gyroscopic precession
> should not be talked of as a left turning tendency except in the
> proper context.
>
> ------------------------------------------------------------------------
> From: jcu...@execulink.com
> To: aer...@westmont.edu
> Date: Wed, 16 Feb 2011 13:59:18 -0500
> Subject: Re: [f-AA] Gyroscopic precession can produce a RIGHT
> turning tendency
>
> I am a bit slow ,in rereading a few times I think I'm with you !!
> They say always left, But as you say in lowering the tail(nose
> raised) or a quick climb input,why is there not a precession force
> for a right turn ? Gets me thinking as we wheel land and lower
> the tail at ending there must be a small right force also but the
> prop is not at high rpm so that particular precession force is
> very small in that situation ?? Just yesterday when up enjoying
> great weather I pondered stuff similar like left vs right turn
> input needs and forces that combine to vary side to side
> outcomes.Makes for a great excuse to go flying,(scientific
> investigation) My best way to describe precession to none flyers
> is to mention a big hand grinder wound up and moved around it
> helps to understand.
>
> ----- Original Message -----
> *From:* Ryan Lunde <mailto:n85...@hotmail.com>
> *To:* aer...@westmont.edu <mailto:aer...@westmont.edu>
> *Sent:* Wednesday, February 16, 2011 12:04 PM
> *Subject:* [f-AA] Gyroscopic precession can produce a RIGHT
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jay curtis
a truely wild looking beast ! I think I saw one at Oshkosh museum. My
Grandfather flew an Armstrong-Whitworth AW 160 fk8 (big ack)in the 1st war.
He passed on before I got the bug.
Subject: Re: [f-AA] Gyroscopic precession can produce a RIGHTturning
tendency
>I believe that that was what initiated the left circuit. it being too
> dangerous to turn right close to the ground. It was the Gnome Rotary,
> may be there were others.
>
> Ian
_______________________________________________
Tony Markl
takeoff and this is totally different from airborne as the wheels are on the ground. Just OMO
Tony Markl
www.tailwheel-and-fabric-spoken-here.com
"Fabric work done or taught at your location"
On 2/16/11 12:04 PM, Ryan Lunde wrote:
I was attending a private pilot ground school that some friends of mine host so that I could brush up on some material for my upcoming CFI checkride. The instructor was discussing left turning tendencies and stated they are most prevalent in slow, high angle of attack attitudes. As we all know, assuming a standard clockwise-from-behind prop, such attitudes require right rudder to compensate for the very real left turning tendencies of torque, spiraling slipstream, and P-factor. Gyroscopic precession was also mentioned and I took it for granted, but then I got to thinking about it a bit more. Gyroscopic precession is almost always discussed in literature in the context of raising the tail of a taildragger on the takeoff roll and we all notice the increased right rudder required at this stage of flight. If you imagine where the force is acting on the prop to push the nose down, it would be at the top of the arc. Gyroscopic precession dictates that the force applied on a spinning object will be redirected 90 degrees from the point of application in the direction of rotation. In our tail raising scenario, force is applied at the top of the prop, but it acts at the 3 o'clock position, causing a left turning tendency. Now, what rattled my thinking was that if the nose were raised, the force would be applied at the bottom of the disk (6 o'clock), the force would act at the 9 o'clock position causing a RIGHT turning tendency. While we often don't experience a need for more left rudder due to the net force (the sum of the other three forces) still resulting in a left turning tendency, if all of the forces were to be accounted for, gyroscopic precession could not be counted as a left turning tendency while raising the nose and doesn't cause any force as long as the nose is being held in a steady attitude. I brought this to their attention after class, but my logic was dismissed. As long as we're not talking about planes powered by British or Russian engines, Gyroscopic precession is always a left turning tendency, I was told. I did some more research and I stand by my assessment. Anybody else care to weigh in?
-Ryan
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Don Harvie
We had an airport committee meeting the other night, and were talking
about flying taildraggers etc. and Dave who flies a Champ made the
comment, right rudder on take off & left rudder on landing.
His argument was the the normal offset of the rudder and/or thrust line
[in our aircraft] is usually meant to compensate for cruise power and
when landing with no or low power, left rudder is needed to remove the
builtin [now] overcompensation for the P-factor.
I've never noticed this and am usually just concentrating on keeping it
straight. I don't think I consciously apply right rudder on takeoff
either but I'm sure it's there keeping me straight on take off too.
I have a pic of Dad in the Chief showing a takeoff with cross wind from
the right. There is considerable right rudder applied despite this
being opposite what would be needed for the crosswind. Here is the pic:
<http://harvie.cable.nu/gallery2/main.php/v/Don/Flying/Aeronca_VH-IDH/testflight2/IMG_9001_crop.JPG.html>
For me this image more than anything else highlighted the need to
compensate for P-Factor etc. on takeoff.
As for gyroscopic tendencies the precession forces that occur because
we're 'pushing' on a gyroscope, (the spinning prop) would be greatest at
higher RPM. When we raise the tail on takeoff we're also close to visual
clues that highlight any change in direction that might occur as a
result of the precession force.
When we lower the tail and get a right turn force from the 'gyroscope',
if we're in the air at full power for a climb, we are probably already
compensating for a greater P-factor trying to turn us left so the
smaller right turning tendency from the tilted gyroscope is somewhat
lost in the other forces acting on the aircraft.
In a power off condition when I raise the nose I'm usually thinking
about stalls and am on the rudder keeping the 'ball in the middle'. The
gyroscopic forces here are also lessened with lower RPM(power). So again
I think it gets lost in the greater picture.
Similarly when wheel landing and we lower the tail we know that it's the
most critical phase and may already have applied some left rudder to
keep straight without being consciously aware, as a result of the
airframe configuration mentioned above. The low RPM again would minimise
the effect.
I think a right turn tendency as a result of gyroscopic precession must
exist, except that it mostly gets lost in the bigger picture of whatever
else is occurring at the time.
Don H
_______________________________________________
Rich Dugger
analyzing it so much ahead of time. You really can't predict what is gonna
happen.
You just have to deal with it.
Rich
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From: "Don Harvie" <donh...@yahoo.com.au>
Sent: Thursday, February 17, 2011 7:32 PM
To: <aer...@westmont.edu>
Subject: Re: [f-AA] Gyroscopic precession can produce a RIGHT
turningtendency
> Ryan,
Don Harvie
across.
Don
On 18/02/2011 1:24 PM, Rich Dugger wrote:
> I guess I just do what needs to be done to fly the airplane without
> analyzing it so much ahead of time. You really can't predict what is gonna
> happen.
>
> You just have to deal with it.
>
>
>
> Rich
>
>
>
> If you plan to forward this message please delete the previous forwards. Not
> only does it make it easier for your recipient to enjoy the message but it
> protects your email buddies addresses and privacy. It will be appreciated!
>
>
> --------------------------------------------------
> From: "Don Harvie"<donh...@yahoo.com.au>
> Sent: Thursday, February 17, 2011 7:32 PM
> To:<aer...@westmont.edu>
> Subject: Re: [f-AA] Gyroscopic precession can produce a RIGHT
> turningtendency
>
>> Ryan,
>>
>> We had an airport committee meeting the other night, and were talking
>> about flying taildraggers etc. and Dave who flies a Champ made the
>> comment, right rudder on take off& left rudder on landing.