What is the total lift for a fixed wing plane and helicopter?

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Discussion Overview

The discussion centers on calculating the total lift for a fixed wing plane and a helicopter, considering various parameters such as wing dimensions, angle of attack, and air properties. Participants explore theoretical frameworks and assumptions related to lift generation in both scenarios.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether the lift equations for fixed wings and propellers are the same.
  • Another participant notes that air properties and airfoil shape significantly influence lift calculations.
  • A participant highlights the impact of Reynolds number and flow separation on lift, suggesting that at a low Reynolds number, the wing may experience stalled flow.
  • There is a proposal to use lifting line theory for estimating lift, though its applicability is questioned due to assumptions about inviscid flow.
  • A participant suggests considering an ideal scenario where the air is still, and the wings are perfectly shaped to maximize lift, raising questions about the implications of wing width on lift at lower speeds.
  • One participant proposes using thin airfoil theory for an upper bound estimate of lift.
  • Another participant states that there is no standard equation for lift applicable to all aerodynamic situations, indicating the complexity of the topic.
  • A participant distinguishes between the lift generated by a helicopter's rotary wing and its propeller.

Areas of Agreement / Disagreement

Participants express differing views on the applicability of various theories and assumptions in calculating lift, indicating that multiple competing perspectives remain without consensus on the best approach.

Contextual Notes

Participants acknowledge limitations such as the dependence on airfoil shape, the effects of Reynolds number, and the complexity of aerodynamic forces, which are not resolved in the discussion.

KuriousKid
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I came to know that Fixed wing as well as propeller lift equations are same [Am I right]?

Anyways I have question.

What's total lift for fixed wing plane with Wing length of 4 m, 1 m width, Angle of attack = 16 degree, and Wind/plane speed of 6 m/s?

Secondly, what's total lift for Helicopter with propeller diameter of 4 m, width of 1 m and Rpm of 420? Considering angle of attack = 16 degrees?

Any one care to explain in detail?

Surely, I will have follow up questions but let's divide and conquer :)
 
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It also depends on the air properties and the airfoil shape...
 
This is a difficult question to answer. Like russ said it depends on airfoil shape but it will also depend on whether or not certain parts of the wing are stalled. For a wing with a chord of 1m and velocity of 6m/s in air the Reynolds number is approximately 380000 which is pretty low. At this low Reynolds number and and angle of attack of 16 degrees there will almost certainly be regions of separated flow over the wing. The entire wing may even be stalled.

For a wing, the easiest way to get an estimate of the lift is lifting line theory. Unfortunately LLT assumes the flow is inviscid, which is a poor assumption in your case since there will be regions of separated flow. However it is possible to get decent estimates with this method by using experimental data for the airfoil as opposed to the thin airfoil theory result which determines the sectional lift coefficient assuming inviscid flow.
 
Thank you for your replies. Let's consider it's quite air. Air Not flowing, but wings are in speed. No stalling. Wings are in perfect or ideal shape for max lift.

I'm just setting hypothetical envioronment saying everything is ideal as it should be :)

Second question for wing's width in both cases. Having more width at lower speed is'nt benefitial (contributing factor) for more lift?
 
If you want an upper bound on your lift the easiest thing to do would be to treat your wing as an airfoil and then use thin airfoil theory.
 
What would be equation in either case for Thin Foil Theory?
 
KuriousKid said:
What would be equation in either case for Thin Foil Theory?

There is no standard equation for lift or any sort of general case for any sort of aerodynamic force. The situation is much more complicated than that.
 
One simple observation: A helicopter's lift is generated by its "Rotary Wing", and NOT its propeller.
 

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