Flight scales badly to slow speeds. Let me demonstrate with some very rough calculations:<p>Imagine three aircraft flying the same distance.<p>The first is a large airplane flying at 20 m&#x2F;s. Solar impulse speed.
The second is a large airplane flying at 200 m&#x2F;s. Basic propeller plane.
The third is a small airplane flying at 200 m&#x2F;s.<p><pre><code>    Slow plane:
    speed: 1x
    area: 1x
    lift: 1x
    payload: 1x
    drag: 1x
    thrust: 1x
    power: 1x
    distance: 1x
    energy: 1x
    
    Big fast plane:
    speed: 10x
    area: 1x
    lift: 100x
    payload: 100x
    drag: 100x
    thrust: 100x
    power: 1000x
    duration: 0.1x
    distance: 1x
    energy: 100x
    
    Small fast plane:
    speed: 10x
    area: 0.01x
    lift: 1x
    payload: 1x
    drag: 1x
    thrust: 1x
    power: 10x
    duration: 0.1x
    distance: 1x
    energy: 1x

</code></pre>
You can see that you use the same energy per payload no matter how fast you go, but your plane can be a lot smaller if you go fast.<p>(This didn&#x27;t take into account altitude. That means you can go even faster for the same energy expenditure.)