Forums: Skydiving Disciplines: Swooping and Canopy Control:

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Mike.d  (C 107643)

Jul 15, 2010, 10:58 AM
Post #26 of 48 (1012 views)
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Doesn't pulling on rears change your angle of incidence, not angle of attack?

To be honest im not to sure this is what i briefly read up on my self -

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Other terms for angle of incidence in this context are rigging angle and rigger's angle of incidence. It should not be confused with the angle of attack, which is the angle the wing chord presents to the airflow in flight. Note that some ambiguity in this terminology exists, as some engineering texts that focus solely on the study of airfoils and their medium may use either term when referring to angle of attack. The use of the term "angle of incidence" to refer to the angle of attack occurs chiefly in British usage

An im no aerodynamics guru buy a long shot, but i think angle of incidence is in built into the design, angle of attack is chord line of the wing and the vector representing the relative motion between the wing and the atmosphere variable buy the means of flaps positive or negative or in our case one direction by the means of our rears.

Thats my interpretation anyway.

castrodavidd  (C 33299)

Jul 15, 2010, 11:26 AM
Post #27 of 48 (1009 views)
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Angle of attack. The acute angle formed between the chord line of an airfoil and the direction of the air striking the airfoil.

Angle of incidence. The angle formed by the chord line of the wing and a line parallel to the longitudinal axis of the airplane.

kallend  (D 23151)

Jul 16, 2010, 5:40 AM
Post #28 of 48 (974 views)
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oh shall we start talking about rears as well, changing our angle of attack. To be honest get a neptune 3 an plug it into a PC it will spert out all the info of decent rates etc etc, and you can draw pie charts and graphs etc etc till they come out your ears.

Kallend
I have to say im very shocked with your experiance you have not heard of a polar curve though this is very basic stuff when coming to flying.

I think you MISREAD my post. castrodavidd said HE hadn't heard of polar curves

kallend  (D 23151)

Jul 16, 2010, 5:43 AM
Post #29 of 48 (972 views)
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Quote:
At what level did you teach aerodynamics? I have yet to see a text book on airplane aerodynamics that didn't include polar curves.

My experance in aviation is Flying for 12 years professional since 2003. I flew CH-47 in the Army and currently fly corporate jet for a living. I have been a flight instructor since 2005 on both airplanes and helicopters. I hold a Comercial license with an instrument rating for Airplanes multi and single engine land, and helicopters. CFI both airplanes and helicopters and three type ratings. DA-20, IA-Jet, and CH-47. Whats yours.
Also I can't find a polar curve in the "pilots handbook of Aeronautical Knowledge" witch is considered the primary source the FAA request Instructors teach from. Maybee I just missed it.

I was thinking REAL aerodynamics, such as is taught to those who design airplanes and helicopters. Has stuff like differential equations in it.

(This post was edited by kallend on Jul 16, 2010, 5:43 AM)

kallend  (D 23151)

Jul 16, 2010, 5:46 AM
Post #30 of 48 (968 views)
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Angle of attack. The acute angle formed between the chord line of an airfoil and the direction of the air striking the airfoil.

.

Poor definition. The air striking the airfoil has an indeterminate direction due to the presence of the airfoil. The reference direction is the free stream direction of the airflow.

castrodavidd  (C 33299)

Jul 16, 2010, 9:17 AM
Post #31 of 48 (953 views)
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I was thinking REAL aerodynamics, such as is taught to those who design airplanes and helicopters. Has stuff like differential equations in it.

Sorry I was thinking of the practical application of aerodynamics that us skydivers actually use in flight.

castrodavidd  (C 33299)

Jul 16, 2010, 9:20 AM
Post #32 of 48 (950 views)
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Poor definition. The air striking the airfoil has an indeterminate direction due to the presence of the airfoil. The reference direction is the free stream direction of the airflow.

Once again sorry, I just copied and pasted the definition from the text book. So that there wasn't my opinion just an acutal definition.

kallend  (D 23151)

Jul 16, 2010, 9:23 AM
Post #33 of 48 (943 views)
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Poor definition. The air striking the airfoil has an indeterminate direction due to the presence of the airfoil. The reference direction is the free stream direction of the airflow.

Once again sorry, I just copied and pasted the definition from the text book. So that there wasn't my opinion just an acutal definition.

Get a proper text book. You know, one with equations and polar curves and stuff like that in it.

The airfoil disturbs the airflow so you can't measure angles relative to the airflow anywhere near the airfoil. The angle of attack is defined relative to the free-stream direction, which is the direction of the flow far enough from the airfoil to be undisturbed.

(This post was edited by kallend on Jul 16, 2010, 9:31 AM)

Mike.d  (C 107643)

Jul 16, 2010, 9:31 AM
Post #34 of 48 (934 views)
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oh shall we start talking about rears as well, changing our angle of attack. To be honest get a neptune 3 an plug it into a PC it will spert out all the info of decent rates etc etc, and you can draw pie charts and graphs etc etc till they come out your ears.

Kallend
I have to say im very shocked with your experiance you have not heard of a polar curve though this is very basic stuff when coming to flying.

I think you MISREAD my post. castrodavidd said HE hadn't heard of polar curves

Sorry about that, i think i had read it correctly just typed what i want to say to whom incorrectly

linebckr83  (D 30571)

Jul 16, 2010, 9:32 AM
Post #35 of 48 (933 views)
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I have only about 3 years experience as an Aerospace Engineer in Advanced Design and have been looking at drag polar curves on a daily basis. Not to mention everyday in Flight Dynamics class. Seems like a pretty common thing to me.

castrodavidd  (C 33299)

Jul 16, 2010, 9:32 AM
Post #36 of 48 (934 views)
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OK I want everyone to read this and see if you think this can be applied to the difference in your speed vs. distance between two different canopies. Also would it be pratical to use this in flight under those canopies.

Quote:
I think you MISREAD my post. castrodavidd said HE hadn't heard of polar curves

Quote:
You may be thinking, "This is all very interesting, but how do I use it in the air. I'm not going to carry polar curve charts with me in the glider and draw tangents for each condition I encounter." You are right. The information derived here must be converted to cockpit displays and/or rules of thumb to use in flight.
First let's discuss headwinds and tailwinds. You have to estimate their values so a rule of thumb is as good as anything. If you were to evaluate several different wind conditions graphically, you would find that the tangent point moves about half as far as the origin. Thus, a good rule would be "Add about half the estimated value of a headwind, and subtract about half the value of a tailwind from the Speed to Fly determined for lift or sink."

For lift and sink we have an instrument in the glider to give us the necessary information. The process used to determine Speed to Fly gives us the sink rate of the air mass and the sink rate of the glider within the air mass. Their total is the value that would be indicated on the variometer. We could select a few representative values of Speed to Fly and stick them on the panel adjacent to the corresponding variometer readings, using a label maker. A better method is to invest in a speed ring for the glider/variometer combination we have. The speed ring is adjustable, but for our current definition of Speed to Fly it should be set with the arrow on the ring pointing to "0" on the variometer. Then when the variometer points to any rate of descent it is also pointing to the corresponding Speed to Fly - the one that will produce the flattest glide under those conditions. Our example shows Speed to Fly varying from 42 kts in still air to 62 kts in 3 kt sink.

Quote is from kallend's link to a site on polar curves.

(This post was edited by castrodavidd on Jul 16, 2010, 9:53 AM)

castrodavidd  (C 33299)

Jul 16, 2010, 9:40 AM
Post #37 of 48 (929 views)
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I have only about 3 years experience as an Aerospace Engineer in Advanced Design and have been looking at drag polar curves on a daily basis. Not to mention everyday in Flight Dynamics class. Seems like a pretty common thing to me.

Occupation: student, aerospace engineer intern
Why dont you put your real qualifications when you post.

Mike.d  (C 107643)

Jul 16, 2010, 11:09 AM
Post #38 of 48 (915 views)
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Look there are so many variable for turn hight wind strength, direction, the discipline you are doing etc etc.

At the end of the day you are the only one who can work these out. An that means getting in the plain a repeating drills lots of times.

If you jump two canopies you also have to train twice as much effectively.
An if you want to lower the risk an no doubt aid you in improving your skills at a faster pace get your cash out for a coach.

At the end of the day big boys rules.

castrodavidd  (C 33299)

Jul 16, 2010, 9:23 PM
Post #39 of 48 (877 views)
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I'll drink to that. Beer Light?

kallend  (D 23151)

Jul 18, 2010, 3:36 PM
Post #40 of 48 (800 views)
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Quote:
I have only about 3 years experience as an Aerospace Engineer in Advanced Design and have been looking at drag polar curves on a daily basis. Not to mention everyday in Flight Dynamics class. Seems like a pretty common thing to me.

Occupation: student, aerospace engineer intern
Why dont you put your real qualifications when you post.

So an aero student sees polar curves on a daily basis (which as an engineering professor I do not doubt), but you claim to teach aerodynamics and had never heard of them.

Says a lot.

castrodavidd  (C 33299)

Jul 19, 2010, 3:36 PM
Post #41 of 48 (748 views)
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Ok, Since I guess were gonna start this up again. Your profile says your a professor but you are trying to explain glide ratios of two different canopies by using a polar curve. YOUR AN IDOT! There I said it.
A polar curve is a tool GLIDER pilots use to change glide ratios for a single aircraft. One polar curve chart will not work to explain why two different gliders have different glide ratios. If you cant understand this, go back to school. My sugestion is start with aerodynamics 101 because this is some pretty basic stuff.
How much does that say?

NWFlyer  (D 29960)

Jul 19, 2010, 3:49 PM
Post #42 of 48 (745 views)
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Oh, the irony.

ianmdrennan  (D 25821)
Moderator
Jul 19, 2010, 5:16 PM
Post #43 of 48 (737 views)
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And you're outta here for 10 days.

Cool your jets. No PA's allowed.

phoenixlpr  (D 3049)

Jul 20, 2010, 5:20 AM
Post #45 of 48 (688 views)
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A polar curve is a tool GLIDER pilots use to change glide ratios for a single aircraft. One polar curve chart will not work to explain why two different gliders have different glide ratios. If you cant understand this, go back to school. My sugestion is start with aerodynamics 101 because this is some pretty basic stuff.
If you can not recognize a type of wing you got a problem.

A glider has a fixed and solid wing. You fly an airfoil. Can you see any difference???

linebckr83  (D 30571)

Jul 20, 2010, 10:21 AM
Post #46 of 48 (648 views)
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Quote:
I have only about 3 years experience as an Aerospace Engineer in Advanced Design and have been looking at drag polar curves on a daily basis. Not to mention everyday in Flight Dynamics class. Seems like a pretty common thing to me.
Occupation: student, aerospace engineer intern
Why dont you put your real qualifications when you post.
I'm not sure where I was mistaken here. I said class, and you highlight that I'm a student...

My job is not to make copies. I do the same thing as every other engineer here. After 3 years as an intern, I work on high priority stuff every day, but for a fraction of the cost to the company. Experience is experience.

I will be a 5th year senior this fall, and every single aero or flight dynamics class I've been in involves reading or creating polar curves.

kallend  (D 23151)

Jul 21, 2010, 10:50 AM
Post #47 of 48 (599 views)
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Ok, Since I guess were gonna start this up again. Your profile says your a professor but you are trying to explain glide ratios of two different canopies by using a polar curve. YOUR AN IDOT! There I said it.
A polar curve is a tool GLIDER pilots use to change glide ratios for a single aircraft. One polar curve chart will not work to explain why two different gliders have different glide ratios. If you cant understand this, go back to school. My sugestion is start with aerodynamics 101 because this is some pretty basic stuff.
How much does that say?

I think it says a lot about you and nothing about me.

castrodavidd  (C 33299)

Aug 2, 2010, 8:37 PM
Post #48 of 48 (483 views)
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A glider has a fixed and solid wing. You fly an airfoil. Can you see any difference???

This is great! Can you explain to me what you think the differences is between an airfoil and a wing? I would love to hear it.
Also no one has answered my question on how you can use a polar curve to explain the difference on why two different canopies glide differently. Some one please explain.

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