# Can We Build a Space Plane? **URL:** \ **Category:** Factual Questions\ **Created:** [April 6, 2005, 11:30pm UTC](https://boards.straightdope.com/t/can-we-build-a-space-plane/298118 "2005-04-06T23:30:12Z")\ **Posts on this page:** 4\ **Page:** 2
**Author:** ![Washoe](https://avatars.discourse-cdn.com/v4/letter/w/ecae2f/32.png) [@Washoe](https://boards.straightdope.com/u/Washoe)\ **Post date:** [April 19, 2005, 1:48am UTC](https://boards.straightdope.com/t/can-we-build-a-space-plane/298118/21 "2005-04-19T01:48:30Z")
Can you explain that more fully or point to a web page that can? I can’t visualize that in my head—it seems impossible. ---
**Author:** ![Sam\_Stone](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Sam\_Stone](https://boards.straightdope.com/u/Sam_Stone)\ **Post date:** [April 19, 2005, 3:11am UTC](https://boards.straightdope.com/t/can-we-build-a-space-plane/298118/22 "2005-04-19T03:11:40Z")
Just do a search on this board. There have been tons of threads about it. ---
**Author:** ![Ale](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@Ale](https://boards.straightdope.com/u/Ale)\ **Post date:** [April 19, 2005, 3:27am UTC](https://boards.straightdope.com/t/can-we-build-a-space-plane/298118/23 "2005-04-19T03:27:04Z")
> [@Washoe](#): > > Can you explain that more fully or point to a web page that can? I can’t visualize that in my head—it seems impossible. Action and reaction, get a spoon and place it bellow the faucet, holding it loosely by the handle between your thumb and your index, like a pendulum, let the water run down the convex face and see how it is deflected “down” (just think the spoon is a wing and the water the air moving over it) and see how the spoon “lifts”; all that´s happened is that the water followed the surface of the spoon that directed it towards one side, since there´s a mass moving in a direction an equal and opposite force is applied in the other direction; thus you get lift. That explains why a wing can generate lift even if it has a symetrical or flat airfoil. Go read [this](http://www.aa.washington.edu/faculty/eberhardt/lift.htm) for a more nuanced explanation. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [April 19, 2005, 7:01am UTC](https://boards.straightdope.com/t/can-we-build-a-space-plane/298118/24 "2005-04-19T07:01:17Z")
> [@Ale](#): > > That´s a misconception; the bulk of the lift generatd by a wing comes from the reaction to a mass of air being moved down, diverted by the airfoil and angle of attack of the wing. _sigh_ I don’t want to get into the discussion–there’s another ongoing thread that has been hijacked by this very issue–but we’re talking oranges and citrus here. Yes, the forward movement of the plane and the angle of the wing with respect to the “static” atmosphere (angle of attack) creates a downward force on the air that causes an upward reaction on the wing, but this is same thing as [Bernoulli’s Principle](http://en.wikipedia.org/wiki/Bernoulli%27s_principle) causing a pressure differential between the upper and lower wing surfaces. The problem comes in where people make incorrect assumptions about the condition of the wing and behavior of the fluid, i.e. a “symmetrical” wing cross-section still has to have a positive [angle of attack](http://en.wikipedia.org/wiki/Angle_of_attack) in order to maintain level flight. Mathematically, Bernoulli’s Principle is only explicitly solvable within a boundary, i.e. a control volume which bounds all steamlines of all particles. Bernoulli’s Equation places some additional restrictions which make it impractical for representing real-world flows (compressable, nonstead, viscous) over a wing, and solutions in computational fluid dyamics are general obtained by approximate, iterative solutions of Euler or Navier-Stokes equations. However, the principle still applies. Stranger [Previous page](https://boards.straightdope.com/t/can-we-build-a-space-plane/298118.md?page=1)