error in the "will the plane take off"

He doesn’t actually mention the Bernoulli principle. Regardless of whether air is “deflected downwards” (which understates the importance of what happens over the top of the wing), or “travels faster over the top compared to the bottom” (which is true even for a flat plate, but the reason given is flawed), or “turned”, the ultimate effect must be the same: for a wing to generate lift there must be an area of lower pressure above it compared to the pressure below it. This is all he has said and it is about as accurate as you can be without offending someone somewhere.

And yeah, in real life prop aircraft, the lift generated by the propwash over the wing is minimal. It has a small effect on the behaviour of the aircraft as the wing stalls but that is about all. Otherwise I’d be in danger of lifting off the ground when doing full power engine runs against the brakes!

And you’d be better off rotating the engines 90 degrees and calling the thing a helicopter.

Ever visit the Everglades?

Missing the point, I think, John. Those work by pushing air. They don’t work by pushing air into the sails of the ship.

Yes. Thank you.

Would one be allowed, outside of the pit, to respectfully call someone an idiot and kindly suggest they return to whence they came? Because if one were, I might be inclined to say so to Dr Max (or whatever his screen name is). Although that might be rude, so perhaps I’ll refrain.

Yes, but that’s not what he said.

Anyway, I already pointed out the problem with his logic in my previous posting. Pulling yourself up by your bootstraps or using fans on your own sails is a zero-net-force situation. Airplane propellers are not (if they were, no plane would ever take off).

(And yet the “using fans on your own sails” situation is actually more complex than that. Ever hear of a Flettner rotor ship?)

Nothing to add, just wanted to say it’s realizations like this thread that make me glad I re-upped earlier today.

True and true. Problem here is that neither analogy is really equivalent to what happens with the airplane wing, although John’s is closer. Problem is, with both swamp boats and self-propelled sailing ships, we’re talking about purely horizontal airflow, thrust, and motion.

However, with the airpalne, the question is whether a prop thrusting horizontally will create enough flow over the wing to lift the plane vertically. Different set of vectors.

In an earlier thread, guest **smellsofbikes ** says,

That pretty much seems to match with John’s intuition that a normal aircraft won’t fly with just the engine backflow, but an overpowered one might.

Yes, well, I wasn’t saying that the propeller wash over the wing thing wouldn’t work, just pointing out that the analogy used was based upon an inaccurate understanding of what the prior poster had said. :slight_smile:

Sorry; I wasn’t necessarily disagreeing with you, just using your post as a jumping-off point to continue the conversation.

Not needed (nor would it be heeded).

Dr Max came, answered and left (victoriously, at least in his mind).

No, that would not be allowed. But I think you knew that. Insults, whether direct or implied, are not permitted in this forum. Don’t try this ploy again.

bibliophage
moderator CCC

On the thread about Human Cannonballs Cecil, peace be unto him, mentions the first such projectile, a “Young woman named Zazel”. Actually it was a young man who at that point in his career posed as a woman becasue his mentor, The Great Farini, thought it made better theatre. “Farini” was a Canadian, an early tightrope walker and the first person, I think, to walk a tightrope over Niagara Falls.

The story of both of them (including their real names, which I forget) is in the book “The Great Farini”, a good and interesting read.

Sorry, this was meant ot be a new thread. Forgive a newbie.

Bumping this thread (chose it because it’s recent, and because it contains zut’s definitive post on the subject) to report that Mythbusters has decided to take on the question. The episode will air in December, sez this story. Set your TiVos, people! :slight_smile:

It’s the same mighty, magical force that keeps threads like this popping up when everything has been wrung out of the topic long ago.

The only reason it was a man was because they couldn’t find a woman of the right caliber. :slight_smile:

So the plane didn’t take off? :wink: Guess they screwed up somewhere.

Knowing Mythbusters, I suspect the plane revved up, lurched forward, slewed off the runway, careened wildly toward the camera crew, tipped onto its nose, and exploded in a ball of flame.