<story><title>NASA reveals what the final X-57 all-electric X-plane will look like</title><url>https://newatlas.com/aircraft/nasa-images-final-x57-electric-x-plane/</url></story><parent_chain><item><author>redis_mlc</author><text>The X-plane program does fundamental research. All military and commercial aircraft have benefited from that research, in the same way WW2 German designs also influenced the world.&lt;p&gt;X-57 is fundamental research, not an effort to create a final product. The closest program similar to it is the X-29, which investigated forward-swept wings, canards and augmented computer systems to control them. (Nobody wants forward-swept wings because a failure in wingtip rigidity or the computer software destroys the structure.)&lt;p&gt;As a commercially-rated airplane pilot and informal aerodynamics student, I think the wingtip propellers are questionable, and the retractable inboard propellers sound like a maintenance and operations nightmare.&lt;p&gt;What&amp;#x27;s weird about mounting propellers at the end of the wing is that you lose half the lift of the propeller wash over the wing, over a normal placement.&lt;p&gt;What&amp;#x27;s misunderstood about wing tip vortices is that regardless of what the loss is, that flow comes from the entire wing producing lift, so is unavoidable. There are already passive techniques like winglets and fences to direct vortices that don&amp;#x27;t require daily maintenance.&lt;p&gt;And we know from the Osprey that complex propeller systems fail too often. A dozen propellers means an order of magnitude more inspections, replacements, ground time (AOG), etc.&lt;p&gt;At $83,000&amp;#x2F;hour to operate, a V22 Osprey is more expensive than an A380. Also, read the section on &amp;quot;Design Challenges&amp;quot;:&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Bell_Boeing_V-22_Osprey&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Bell_Boeing_V-22_Osprey&lt;/a&gt;&lt;p&gt;Additionally, there is no &amp;quot;urban air mobility market&amp;quot; in the USA, and never will be, due to regulation and insurance requirements. In a showdown between the FAA and Uber, the FAA will always win, and the FAA reserves the perogative to change its mind later, as in drone regulation.&lt;p&gt;To give you an idea, it was easier to start SpaceX than it would be to get the FAA to allow &amp;quot;urban air mobility.&amp;quot; So regulation is the real challenge, not technology.</text></item></parent_chain><comment><author>bdamm</author><text>&amp;gt; What&amp;#x27;s weird about mounting propellers at the end of the wing is that you lose half the lift of the propeller wash over the wing, over a normal placement.&lt;p&gt;They&amp;#x27;re generating lift at low speeds by using the array of small motors, and then optimizing the wing for cruise lift. It&amp;#x27;s really brilliant. And it&amp;#x27;ll result in better handling in turbulence too. Frankly I&amp;#x27;m stunned at the direction they&amp;#x27;ve gone here, it&amp;#x27;s really remarkable and is a major shift in approach to aerodynamics that has huge implications across the industry.</text></comment>
<story><title>NASA reveals what the final X-57 all-electric X-plane will look like</title><url>https://newatlas.com/aircraft/nasa-images-final-x57-electric-x-plane/</url></story><parent_chain><item><author>redis_mlc</author><text>The X-plane program does fundamental research. All military and commercial aircraft have benefited from that research, in the same way WW2 German designs also influenced the world.&lt;p&gt;X-57 is fundamental research, not an effort to create a final product. The closest program similar to it is the X-29, which investigated forward-swept wings, canards and augmented computer systems to control them. (Nobody wants forward-swept wings because a failure in wingtip rigidity or the computer software destroys the structure.)&lt;p&gt;As a commercially-rated airplane pilot and informal aerodynamics student, I think the wingtip propellers are questionable, and the retractable inboard propellers sound like a maintenance and operations nightmare.&lt;p&gt;What&amp;#x27;s weird about mounting propellers at the end of the wing is that you lose half the lift of the propeller wash over the wing, over a normal placement.&lt;p&gt;What&amp;#x27;s misunderstood about wing tip vortices is that regardless of what the loss is, that flow comes from the entire wing producing lift, so is unavoidable. There are already passive techniques like winglets and fences to direct vortices that don&amp;#x27;t require daily maintenance.&lt;p&gt;And we know from the Osprey that complex propeller systems fail too often. A dozen propellers means an order of magnitude more inspections, replacements, ground time (AOG), etc.&lt;p&gt;At $83,000&amp;#x2F;hour to operate, a V22 Osprey is more expensive than an A380. Also, read the section on &amp;quot;Design Challenges&amp;quot;:&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Bell_Boeing_V-22_Osprey&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Bell_Boeing_V-22_Osprey&lt;/a&gt;&lt;p&gt;Additionally, there is no &amp;quot;urban air mobility market&amp;quot; in the USA, and never will be, due to regulation and insurance requirements. In a showdown between the FAA and Uber, the FAA will always win, and the FAA reserves the perogative to change its mind later, as in drone regulation.&lt;p&gt;To give you an idea, it was easier to start SpaceX than it would be to get the FAA to allow &amp;quot;urban air mobility.&amp;quot; So regulation is the real challenge, not technology.</text></item></parent_chain><comment><author>starpilot</author><text>Re: Osprey, the X-57&amp;#x27;s electric motors are &lt;i&gt;vastly&lt;/i&gt; simpler than the fueled gas turbines + driveshafts in that aircraft. All you do is run wiring down the wings, with the Osprey you&amp;#x27;re running pressurized, flexible fuel lines into a movable nacelle with enormously complex turbomachinery to do all of the compression + combustion. These things are a pandora&amp;#x27;s box of fatigue problems from the multimodal vibrations and it takes years to analyze them all.&lt;p&gt;You also can&amp;#x27;t compare operating costs of a military vs. civil aircraft. VERY different priorities, military aircraft have dramatically higher requirements due to where they operate (desert sand anyone?) and their mission. EVERYTHING gets inspected, components are designed to be performant like Formula 1 race cars and not necessarily for lowest operating costs. It&amp;#x27;s like comparing an M1 tank, which gets 0.5 mpg, to a Ford F150.&lt;p&gt;&amp;gt; What&amp;#x27;s weird about mounting propellers at the end of the wing is that you lose half the lift of the propeller wash over the wing, over a normal placement.&lt;p&gt;This is nonsense, there&amp;#x27;s no rule of the thumb that states any random wing reduces prop thrust by 50%. You must calculate it. It&amp;#x27;s a very complex unsteady flow field dependent on all of the geometries involved. It will vary on flight condition obviously.&lt;p&gt;&amp;gt; informal aerodynamics student&lt;p&gt;I&amp;#x27;m sorry but the average pilot&amp;#x27;s understanding of aerodynamics is very poor. I&amp;#x27;ve seen blatant mistakes in flight manuals. At the least you should know how to explain what Reynolds number and Kutta condition are before diving into these discussions.</text></comment>