Aerodynamics - Question about wingtip shapes

Click For Summary

Discussion Overview

The discussion revolves around the aerodynamic implications of different wingtip shapes on aircraft, specifically comparing rounded and straight wing tips. Participants explore how these shapes may influence roll rate and overall roll performance, touching on historical design choices and theoretical underpinnings.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that rounded wing tips, like those on the Spitfire and A6M Zero, may help avoid tip stalls, while others note that agile aircraft may prefer stalls beginning at the tips for quicker roll response.
  • One participant mentions that modern jet airliners feature wingtips that are extended and bent upwards, implying a design evolution in wingtip shapes.
  • Another participant states that elliptical wing planforms are considered the most efficient, but acknowledges that various factors influence wing shape choices.
  • It is noted that the P-51 Mustang's squared-off wing tips were a design decision aimed at saving time and costs, with no significant loss of efficiency observed.
  • Some argue that while elliptical wings are aesthetically pleasing and theoretically efficient, practical considerations have led to the adoption of square tips in newer designs for benefits like longer ailerons and flaps.

Areas of Agreement / Disagreement

Participants express differing views on the aerodynamic advantages of rounded versus straight wing tips, with no consensus reached on which design is superior or under what conditions. The discussion remains unresolved regarding the overall impact of wingtip shapes on performance.

Contextual Notes

Participants reference various aerodynamic theories and historical design choices, but the discussion lacks detailed mathematical analysis or empirical data to support claims. The effectiveness of different wingtip shapes may depend on specific flight conditions and aircraft types.

marry del
Messages
1
Reaction score
0
Short of picking up an aerospace engineering book and learning a lot of complex math, I figured I'd ask here.

Looking at the wing tips of planes like the Spitfire, P-63 Air Cobra, P-47 Thunderbolt, A6M Zero, etc... you'll notice the wing tips are rounded.

Looking at the wing tips of the P-51, the BF-109, modern Cessnas, FW-190, etc... you'll notice the wing tips are straight.

Does this affect aerodynamics much? Roll rate/roll performance at all? If so, could someone explain why the rounded wings are better/worse?
 
Last edited by a moderator:
Physics news on Phys.org
I have no idea but you might also want to note that modern jet airliners all have the wingtips extended slightly and bent upwards.
 
The round shapes of those wings tried to avoid tip stalls.
They were complex to fabricate.
More agile and acrobatic airplanes prefer the stalls beginning by the tips, so they are quick to roll.

Please, see:
https://en.wikipedia.org/wiki/Elliptical_wing

2H8Bm.jpg
 
  • Informative
  • Like
Likes   Reactions: Klystron, berkeman and russ_watters
Welcome to PF!
marry del said:
Looking at the wing tips of planes like the Spitfire, P-63 Air Cobra, P-47 Thunderbolt, A6M Zero, etc... you'll notice the wing tips are rounded.
More specifically, elliptical.
Looking at the wing tips of the P-51, the BF-109, modern Cessnas, FW-190, etc... you'll notice the wing tips are straight.

Does this affect aerodynamics much? Roll rate/roll performance at all? If so, could someone explain why the rounded wings are better/worse?
Elliptical plan wings are most efficient, but there are many factors affecting the choice of plan. Here's a primer on common shapes:
https://www.aircraftcompare.com/blog/types-of-aircraft-wings/
 
  • Like
Likes   Reactions: Klystron and Lnewqban
Elliptical wing planforms were inspired by Ludwig Prandtl's Lifting Line Theory.

The P-51 Mustang was designed with squared off wing tips in order to save time and cut costs. After engineers noticed no apparent loss of efficiency, squared off tips eventually became the norm.

The rationale behind the constant chord (e.g. Piper Cub) or tapered (e.g. P-39) wing with rounded tips is that it was supposed to yield some of the efficiencies but be easier and less expensive to build than pure elliptical. It turned out to be a mistake, and when Aeronca Champ or Piper Super Cub wings are built new, they have square tips. The side benefit is that the ailerons have a longer moment arm and flaps can be longer.

Elliptical wings hung on for a long time because they appealed to intuition. They look beautiful, efficient and graceful. About the only benefit is higher torsional strength-to-weight and torsional rigidity-to-weight ratio.
 
  • Informative
Likes   Reactions: Klystron