Private Flying LAA/BMAA/BGA/BPA The sheer pleasure of flight.

Polar diagram

Old 13th Dec 2020, 15:03
  #1 (permalink)  
Thread Starter
Join Date: Dec 2007
Location: Meteorology Avenue 17
Age: 41
Posts: 185
Polar diagram

I found it in an old PPL German book. Could someone explain me please the diagram and eventually translate it? Thanks

Attached Files
File Type: pdf
Polardiagramm.pdf (598.5 KB, 154 views)
maximus610 is offline  
Old 13th Dec 2020, 15:13
  #2 (permalink)  
Join Date: Dec 2020
Location: London
Posts: 3
These diagrams do still exist albeit under a fresh name, "Drag Polar Curves".
A320 Glider is offline  
Old 13th Dec 2020, 15:27
  #3 (permalink)  
Join Date: Jul 2010
Location: EBZH
Posts: 2,624
senkrechter Sturz => vertical fall
Rückenflug => inverted flight
Rückentrudeln (not sure, here) => inverted stall
Schnellflug => fast cruise
Reiseflug => cruise
bester Gleitwinkel => optimal rate of descent (or "angle of descent")
maximale Reichweite => maximum range
bestes Steigen => best climb
geringstes Sinken => least descent
Anstellwinkel wird kleiner => decreasing angle of attack
Anstellwinkel wird größer => increasing angle of attack
Abkippen => stall
Klappe => flaps

hope this helps

Jan Olieslagers is offline  
Old 13th Dec 2020, 16:10
  #4 (permalink)  
Join Date: Sep 2016
Location: USA
Posts: 663
Coefficient of drag on the horizontal axis, coefficient of lift (also AOA, as they move together) on the vertical. So unlike most graphs that show whatever you're controlling on the horizontal axis and the result on the vertical, this one shows what you're controlling on the vertical. Each curve shows a certain flap configuration.

The highest point on each curve is the highest lift coefficient, aka stall. You can see the higher the flap setting, the higher the max lift coefficient, meaning the lower the stall speed.

At any point along a curve, the ratio of lift to drag coefficients is represented by the slope between that point and the origin. (The graphical result of dividing top by bottom. Bigger ratio means steeper slope.) So if you're looking for the highest L/D ratio, (meaning the most efficient flight regime) for a particular flap config curve, it'll be shown by finding the spot on that curve that has the steepest slope to the origin, which in essence means where it bulges out the most to the top left. Aka, the tangent point. Here, that max slope is shown for the clean wing ("Polarentengente") and the point of the clean wing curve that touches it is "bester Gleitwinkel." Any lower on the curve, both lift and drag coefficients decrease, but in a ratio such that drag dominates. Any higher, they both increase, but again drag dominates. So that point, your best L/D, is your best glide.

For higher flap settings, you can see their tangent slopes to the origin are shallower, meaning their best lift/drag ratios are less, manning the best glide angle you can achieve is worse. Also those worse best glide angles occur at higher lift coefficients, meaning lower speeds.
Vessbot is offline  
Old 13th Dec 2020, 18:05
  #5 (permalink)  
Join Date: Mar 2017
Location: Earth
Posts: 11
Rückentrudeln => inverted spin
ArrowFly is offline  
Old 13th Dec 2020, 19:18
  #6 (permalink)  
Join Date: Aug 2006
Location: Ontario, Canada
Age: 60
Posts: 4,873
Rückentrudeln => inverted spin
Would that be inverted stall, rather than spin? I don't know German, but I know aerodynamics enough to know that the airfoil would not know if it were stalled, or spinning, just it wasn't creating lift anymore...
Pilot DAR is offline  
Old 14th Dec 2020, 04:47
  #7 (permalink)  
Join Date: Jul 2010
Location: EBZH
Posts: 2,624
No, I was wrong, ArrowFly is right. "Trudeln" does translate to "spin". And "Rücken" to "back", in the anatomical sense.
Jan Olieslagers is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.