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When the DC-8 Went Supersonic (2011)
- freeone3000 9y agoIn a dive.
- 1001101 9y agoIn a commercial passenger jet designed in the 1950's.
- nathanm412 9y agoThe biggest issue wouldn't have been designing a power system that could bring a jet to mach speeds. The bragging rights for them were that the plane survived the transition to mach 1.
- craftyguy 9y agoDoes something magically happen at Mach 1.0 that would compromise structural integrity significantly more than, say, Mach .99...9?
- tim333 9y agoIt seems not quite - supersonic airflow would already be having an effect in places if the plane was doing 0.99 see https://www.quora.com/What-happens-if-an-airliner-reaches-Mach-1-sound-speed-1224km-h-or-768-mph# https://www.quora.com/What-happens-if-an-airliner-reaches-Ma...
- qwerty_asdf 9y agoIf you read the parts where they mention “buffeting” that’s the dangerous part, where uneven airflow introduces instability, causing the airframe to rattle. Buffeting occurs when the soundwaves of the noise of the craft and its motion directly affect the air as it flows across the surface of the plane. This happens as the plane enters the shockwave of the sound barrier, and ceases when they accelerate beyond the speed of sound. At and beyond Mach 1 the buffeting is behind the plane, and flight is smoother, with no rattling or shaking from the incidental turbulence. It also happens when decelerating, although it’s easier to decelerate safely through the buffeting quickly, since less time is spent in the shockwave, and a reduction in speed grants improved control.
- craftyguy 9y agoI see, thanks for the explanation
- scrumper 9y agoGood story, and a great example of test pilot presence of mind as the crew discovers that the elevators don't work...
- throwanem 9y agoWhat surprised me the most was that they did it on purpose!
- mirimir 9y agoTwo reasons are pretty clear from the article. It was fun. And it could be sold to management as safety PR.
- cratermoon 9y agoThe engineering data alone from the flight was worth the risk. What they measured and learned during the flight probably gave the aircraft designers at Douglas priceless insights.
- haltingthoughts 9y agoModern aircraft undergo testing near the speed of sound to find issues as well. https://youtu.be/rpP7hsuVuoE?t=1155 https://youtu.be/rpP7hsuVuoE?t=1155
- giarc 9y agoNot only safety but so they could say they beat Boeing.
- dfrey 9y agoQueue up the Ryan Reynolds "But Why?" gif for this one I think.
- jtchang 9y agoWhat does it mean when he says he pushed over into the dive more? Does that mean he went faster down?
- stcredzero 9y agoYes. To relieve stress on the stabilizer.
- robertely 9y agoYes, it means he pitched down even more.
- bwanab 9y agoI miss the DC-8. Always my favorite jet in my younger days. Those things felt like rockets taking off.
- InTheArena 9y agoNear criminally stupid though. Not only did they have issues with two separate control surfaces, a unplanned stall and a safety violation on takeoff, they did all of these things for a marketing piece establishing the plane was safe. This at a time where metal fatigue and structural load was not well understood, as the Europeans where finding out as their planes decompressed explosively midair. There was a 747-SP that went supersonic by accident and was only saved by the crew deploying the landing gear to slow the plane down. He amount of damage was non trivial. Someone will probably jump all over the critics of Douglas and point out Boeing’s Tex Johnson’s barrel row. 1) that was not endorsed by the company and 2) was a neutral G maneuver. 3) the company appropriately freaked and told him never to do that again. We have occupational safety and standards operating procedures for a reason.
- deleted 9y ago[deleted]
- qwerty_asdf 9y agoSince when is voluntary experimentation on a test rig, under controlled circumstances, criminally stupid? It’s not like this was a passenger flight. It would warrant criticism if the pilot tried it without informing the crew prior to takeoff. All participants entered into the activity with an understanding that they were risking their lives. These people did it because they enjoyed the challenge, not to score points with corporate overlords or jockey for a raise and a promotion. The marketing angle was simply to provide cost justification and demonstrate that a perceptible reward would be earned with the risk undertaken.
- InTheArena 9y agoThat's a optimistic reading of the article. The article states it was for marketing reasons, and also states that they had several plan threating outcomes that were not planned for. If it where in the context of understanding the plane's behavior at trans-sonic speeds, I can understand it, but that is not really given as a justification.
- geezerjay 9y ago