Angle of Incidence

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krines
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Angle of Incidence

Post by krines »

What is the angle of incidence for an A model
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Bruce Fenstermacher
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Re: Angle of Incidence

Post by Bruce Fenstermacher »

Angle of incidence between what? The wing and the ground parked? the stabilizer and the wing?
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lowNslow
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Re: Angle of Incidence

Post by lowNslow »

Angle of Incidence = angle between the chord line of the wing at the fuselage and the fuselage’s longitudinal axis.

What it is supposed to be for the 170, I don't know.
Karl
'53 170B N3158B SN:25400
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krines
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Re: Angle of Incidence

Post by krines »

Yes I am asking the angle between the cord line of the wing and the fuselage or thrust line of the engine
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Bruce Fenstermacher
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Re: Angle of Incidence

Post by Bruce Fenstermacher »

Here is a thread from 2003.

http://cessna170.com/forums/viewtopic.p ... 1106#p7924.
by gahorn » Sat Aug 30, 2003 8:25 pm
The Horizontal Stabilizer angle of incidence is measured across the top of the horizontal stab. spars (ront and back) without regard to the airfoil shape of the skin. (Press the skin down so it won't interfere with the straight-edge.) It's angle is compared to the fuselage splice plate, which is the long piece of aluminum that runs the length of the fuselage on each side. That angle should be -2 degrees, 48 minutes.
The last post reads:
by N2520V » Fri Jun 15, 2007 9:13 pm
I know this is an old thread, but I got a definitive answer from Cessna regarding this measurement on a 48 Ragwing.
Horizontal Stabilizer Angle of Incidence = -4 degrees measured against the leveling reference, upper door sill.
I don't know where George got the answer or what models it is for. I also don't know how the fuselage split plate George speaks of compares to the upper door sill. Perhaps there is -1 degree, 12 minute difference and so all 170s are the same, just a difference how it is measured.
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johneeb
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Re: Angle of Incidence

Post by johneeb »

I have no idea what the Angle of Incidence of the wing is, I do know that we can adjust the angle with the cams at the rear Spars to compensate for a heavy wing.
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nippaero
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Re: Angle of Incidence

Post by nippaero »

Since my wings are off for the winter I have been thinking about this. How does one go about adjusting the cams after attaching the wing? Is it just trial and error by flying and adjusting or is there a more scientific way? The cam doesn't seem like it would move the wing a whole lot at the inboard trailing edge. Maybe a little goes a long way?

What would the flight characteristics be like if it was out of adjustment? Would there be a tendency to drop a wing during a stall?
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bagarre
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Re: Angle of Incidence

Post by bagarre »

nippaero wrote:Since my wings are off for the winter I have been thinking about this. How does one go about adjusting the cams after attaching the wing? Is it just trial and error by flying and adjusting or is there a more scientific way? The cam doesn't seem like it would move the wing a whole lot at the inboard trailing edge. Maybe a little goes a long way?

What would the flight characteristics be like if it was out of adjustment? Would there be a tendency to drop a wing during a stall?
If it's out of adjustment, one wing will feel heavy.
There is a rigging document somewhere on the forum but the idea is that you start out with the eccentrics even and adjust as needed to fly level. Probably a search for rigging would find the thread I'm thinking about.

EDIT:
Found it.
http://www.cessna170.org/forums/viewtop ... 527#p72527
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nippaero
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Re: Angle of Incidence

Post by nippaero »

Thanks David. I'll read through it.
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krines
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Re: Angle of Incidence

Post by krines »

Ok time for more info. I hate to say it but I am no longer the owner of my precious 170. I now am an owner of a super-cub. I will always hold my 1320D in my heart. When landing the supercub on a wheel landing you must be very tail wheel low to accomplish the shortest landing possible, same with the 170. However the tail wheel low in the cub is much lower almost 3 point. The cub has about 4.5 to 5.0 degrees angle of incidence. I suspect the 170 has less. There is a thrust line mod for the cub that bring the incidence closer to zero. I suspect the 170 is closer to zero and that is why I ask. Do tell
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n2582d
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Re: Angle of Incidence

Post by n2582d »

While I don't think this is what you are looking for, I've included Service News Letter (S.N.L.) 07-27-54 "Wing and Stabilizer Rigging Information" here. On the 170B we think the thrust line is 2 degrees nose down. See this thread.
Gary
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krines
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Re: Angle of Incidence

Post by krines »

2 degrees makes some sense to me. While flying just above the runway at the slowest possible speed the 170A seems to be only slightly tail low as compared to my cub which is very tail low. I suspect the angle of incidence is the issue but flaps also contribute some. When you pull flaps on the 170 the nose goes down on the cub it really goes up.
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Re: Angle of Incidence

Post by GAHorn »

Bruce Fenstermacher wrote:...

I don't know where George got the answer or what models it is for. I also don't know how the fuselage split plate George speaks of compares to the upper door sill. Perhaps there is -1 degree, 12 minute difference and so all 170s are the same, just a difference how it is measured.
If you closely read it again you will note that the information was relevant to the angle of incidence of the Horizontal Stabilizer. (not the wing) :wink:
krines wrote:2 degrees makes some sense to me. While flying just above the runway at the slowest possible speed the 170A seems to be only slightly tail low as compared to my cub which is very tail low. I suspect the angle of incidence is the issue but flaps also contribute some. When you pull flaps on the 170 the nose goes down on the cub it really goes up.
Whaaa...???
The thust line has nothing to do with angle of incidence except as a reference point. (And the 170 nose rises when flaps are deployed...not as you suggested. This is because the flaps provide a downward relative wind to the horizontal stabilizer, thereby increasing it's downward lift.... as it behaves as an upside-down wing to keep the nose-heavy airplane's nose pivoted about the center-of-lift created by the wing. Next time you are flying your 170 in a trimmed condition, ...deploy flaps and you will find you must re-trim in a downward direction in order to counteract the rising nose.)
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krines
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Re: Angle of Incidence

Post by krines »

Now that you mention it I guess there was a nose up pitch movement with flap deployment on the 170 but nothing like the cub. The cub flown properly you dont notice it as much but the first couple flights was eye opening. To be clearer on the thrustline issue, if a cub and 170 have thrustlines in line with the fuselage and a cub has a 5 degree angle of incidence and a a 170 has less (the angle of incidence question for the wing remains unanswered) how does this affect flight characteristics of power on approaches. If the cub thrust is pulling down relative to the wing by 5 degrees does it cause one to compensate with a more tail low approach. Say fore instance if the 170 has between 0-2 degree thrustline and angle of incidence power would not pull toward the ground relative to the wing as much requiring less tail down attitude.
bagarre
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Re: Angle of Incidence

Post by bagarre »

How much power are you carrying on final approach to notice the down thrust of the motor?
Are you flying your approach behind the power curve ?
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