Questions About Aerodynamics and Flying Cars- Help

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Discussion Overview

The discussion revolves around the mechanics of lift generation in aerodynamics, particularly focusing on the concept of creating lift through airflow over wings. Participants explore the feasibility of generating lift by blowing air over stationary wings, as opposed to relying solely on forward motion. The conversation touches on theoretical and practical aspects of aerodynamics, including applications in model aircraft and wind tunnel simulations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions why planes need to move to generate lift and suggests that blowing air over a wing could create vertical lift.
  • Another participant confirms that blowing air over a wing can indeed create lift.
  • A different participant mentions that while it is possible to generate lift this way, it may not be practical for forward motion, referencing wind tunnel experiments and a specific aircraft that could take off without moving due to sufficient wind speed.
  • There is a query about whether the lift generated would be vertical if the conditions were precisely measured.
  • Some participants note that certain radio control models achieve lift through prop wash, indicating that this concept is applied in practice.
  • One participant emphasizes the necessity of forward speed for a vehicle to travel effectively, even if lift can be generated by blowing air over the wings.
  • A historical reference is made to a prototype developed in the 1950s that utilized a design to enhance lift through propeller wash, suggesting that similar concepts could be applied with ducted fans.
  • Another participant expresses gratitude for the responses received and inquires about free wind tunnel simulations for further research.
  • Suggestions for software like xfoil are provided, along with a mention of its limitations and assumptions.
  • A recommendation for a book on wing section theory is made, noting its utility for calculating lift but also its limitations regarding complex interactions like prop wash.

Areas of Agreement / Disagreement

Participants generally agree that it is possible to generate lift by blowing air over wings, but there is no consensus on the practicality of this method for actual flight. The discussion includes multiple viewpoints on the necessity of forward motion and the effectiveness of various aerodynamic designs.

Contextual Notes

Some limitations are noted regarding the assumptions made in simulations and the applicability of theoretical models to real-world scenarios, particularly concerning interactions between wings and prop wash.

Who May Find This Useful

This discussion may be of interest to those studying aerodynamics, model aircraft enthusiasts, and individuals looking for resources on wind tunnel simulations and wing design theory.

T.O.E Dream
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Sorry i didn't know where else to ask this so I'm hoping you guys can help anyways.

If a air moving over a wing causes lift then why do planes need to move in order for this to happen. What i mean is instead of moving in order for the air to pass the wing why can't we "blow" air at fast speeds over a wing to create lift. Would this cause vertical lift? Can someone clear things up.

Thanks in advance!
 
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Sure, you can do this. If you blow air over a wing you create lift.
 
We can do that very thing, but it doesn't really get you anywhere. If you consider it from a modeling aspect, that's exactly what happens in a wind tunnel. I have also seen an aeroplane (a German Stork) not only take off without moving, but also fly backwards along the runway because the wind was faster than its minimum stall point. (Stall depends upon both angle of attack and speed.)
 
But will it be vertical lift (considering that you measured everything precisely)?
 
Some very overpowered radio control models almost do this due to the prop wash across the wing.
 
Note, T.O.E., that if you want this vehicle to actually go anywhere, you also need forward speed...
 
This was developed as early as the 50s. (What's the guy's name?...) He built a working prototype where the wing had a channel toward the root of the wing. It was like a dip in the wing with 180 degrees of the propeller wash running through the dip. Significantly greater lift is developed.

Edit: Found it. http://www.scripophily.net/cuschanwinai.html"

There's nothing wrong with your idea, TOE. One could concievably develop lift from stationary wings with air blowing over the top in various directions without requiring forward motion. I can imagine a bunch of ducted fans could do it, which can achieve the same results by the same means, and ducted fans can be redirected for forward motion.
 
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Thanks, these were the answers i was looking for!

By the way does anyone know any free wind tunnel simulations on the internet. I know that you can find how much a wing creates lift by an equation. But you need to find it's lift coefficient which you usually do in a wind tunnel. I'm just doing a bit of research.
 
There are free programs like xfoil that might help. xfoil is a dos (or unix) interactive program. It makes some simplifying assumptions, but I've read that it's reasonably accurate for speeds below 1/3 mach.

http://web.mit.edu/drela/Public/web/xfoil
 
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  • #10
Theory of Wing Sections, Abbot, a Dover reprint, 1959 isn't bad for getting fairly close design values for wings, if that's what you're interested in. Using various equations and graphs, it will allow you to calculate the lift of a particular foil of some fairly simple wing plane-forms such as elliptical, rectangular, or tapered. But just as with Xfoil, which is for single, isolated sections only, it won't help with interacting systems such as a wing subjected to prop wash. The text is available online as a free downloadable ebook in .pdf, if you jump through some login hoops.
 
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