Search found 19 matches

by airshowfan
Fri Oct 15, 2010 12:34 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

(Or perhaps you mean that no physicsts and aero professionals disagree with the Newton explanation? If so, I agree.) I guess that's what I meant. The majority of old K-12 textbook illustrations clearly depict air behind the wing flowing horizontally, with zero downwash. Their explanations don't men...
by airshowfan
Tue Oct 12, 2010 1:48 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

Yesterday I had a chance to fly in a 747-8 simulator at Boeing Field. It's used by the stability-&-control/airplane-handling aerodynamicists to "test" conditions that are too risky to actually test-fly (such as really bad and almost-impossibly unlikely things happening during takeoff a...
by airshowfan
Mon Oct 11, 2010 6:48 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

The proponents of the arguments usually fall into two camps: (1) those who support the "Bernoulli" position that lift is generated by a pressure difference across the wing, and (2) those who support the "Newton" position that lift is the reaction force on a body caused by deflec...
by airshowfan
Mon Oct 11, 2010 12:17 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

the kid that brings up the issue of imaginary numbers is probably not trying to improve the educational process, but showing off, kind of the like the five year old that knows about every dinosaurs, so thinks they know everything. If you read XKCD, you were probably guilty of this at some point. I ...
by airshowfan
Sat Oct 09, 2010 2:23 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

the pressure is decreased by an amount proportional to the extra distance moved Actually, the pressure change is proportional to the change in the square of the speed. But that's a minor nitpick. Overall, you're right. And that's a good way to expose why the equal-distances thing doesn't work, abou...
by airshowfan
Sat Oct 09, 2010 2:10 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

I realize I am arguing with a guy whose name is airshowfan, and neither of us have numbers to back up our armchair engineering I have numbers. But if I shared them, I'd be fired :wink: I also have the FAA requirements which airplane structure is required to meet, and those I can share, because they...
by airshowfan
Sat Oct 09, 2010 1:14 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

Planes can't be designed to be strong from every direction without taking a massive weight penalty, and why would they? Because the FAA says they should. By that I mean: Because, for the sake of safety, the FAA has a huge list of conditions that every certified airplane must survive without damage,...
by airshowfan
Fri Oct 08, 2010 11:31 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

even trying to flip it over will make the controls lock up and the plane instantly do a nosedive into the ground The controls don't "lock up". You just don't have enough elevator authority to overcome the horizontal stabilizer's force that pushes the tail up and the nose down: http://foru...
by airshowfan
Fri Oct 08, 2010 11:11 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

If you throw a rock fast enough, it will generate enough lift to overcome its weight, and will go "up". Anything can go "up" non-sustainably if you get it going fast enough. The question, then, is: at a sustainable descent rate, what is the lift-to-drag ratio? By the way, it equa...
by airshowfan
Fri Oct 08, 2010 8:42 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

I got this answer from asking Google how long can a plane fly upside down. This answer is incomplete and uses technical language in imprecise ways. It strikes me as someone who doesn't know what he's talking about, but trying to hide this by writing a lot. how the wings will "attack" the ...
by airshowfan
Fri Oct 08, 2010 7:17 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

Yeah, that makes sense. While on a boat, the gold is displacing a lot of water (its weight), but once in the water the gold is displacing less water (its volume). Once the gold goes overboard, the boat hull displaces less water corresponding to the weight of the gold, while the gold itself displaces...
by airshowfan
Fri Oct 08, 2010 7:07 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

Floating objects displace their weight in water (which is a lower volume). Sinking objects displace their volume in water (which is a lower weight). Right?
by airshowfan
Fri Oct 08, 2010 5:36 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

The primary function of their wings is not to provide lift, just to balance them and provide coordination. You know that this is incorrect, right? Just checking. This only proves that the equal distance explanation could not be the only reason why something with wings flies... Actually, the incorre...
by airshowfan
Fri Oct 08, 2010 3:59 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0803: "Airfoil"
Replies: 243
Views: 101195

Re: 0803: "Airfoil"

Airplanes can fly upside down (i.e. airfoils can still generate lift upside-down) because the stagnation point changes. (Unfortunately, this is compatible with the incorrect "the separated air must meet up with itself at the trailing edge, so the air taking the longer path must speed up" e...
by airshowfan
Mon Jun 28, 2010 6:55 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0759: "3x9"
Replies: 135
Views: 41924

Re: "3x9" Discussion (#759)

I, too, use this "handy trick" ALL THE TIME. "Prove that blah is equivalent to blah" pretty much means "Start working forwards from this one and backwards from that one and see if you can make them meet in the middle". Well, I do usually manage to close up the seam. And...
by airshowfan
Wed Apr 14, 2010 5:58 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0727: "Trade Expert"
Replies: 172
Views: 45188

Re: “Trade Expert” discussion

I'm with memcginn . I don't really keep track of which one is called "slash" and which one is called "backslash". When typing out a URL I write "/" (whatever that's called), and when going into Windows directories I type "\" (whatever that's called). Whenever ...
by airshowfan
Fri Mar 26, 2010 4:52 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0719: "Brain Worms"
Replies: 140
Views: 28535

Re: "Brain Worms" Discussion

I used to have these driving dreams (from the back seat, swerving all over the road, sometimes brakes don't work) when I was a little kid. I don't think I've had them since I was 12 or 13, definitely not since I started actually driving. (I'm 28 now. And yes, I remember many of the dreams I had when...
by airshowfan
Mon Feb 15, 2010 5:39 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0702: "Snow Tracking"
Replies: 135
Views: 38540

Re: “Snow Tracking” discussion

Shouldn't it be "duplicator", with an O?

Otherwise, great comic :]

(I, too, didn't notice at first how early the jokes started).
by airshowfan
Mon Aug 24, 2009 7:17 pm UTC
Forum: Individual XKCD Comic Threads
Topic: 0627: "Tech Support Cheat Sheet"
Replies: 182
Views: 55695

Re: "Tech Support Cheat Sheet" Discussion

I've been reading XKCD for years. Huge fan. Like many of you, I feel like some strips were plucked right out of my brain. I email them to people all the time. Etc. But this one was so good, it prompted me to actually register for this forum so I could post my thumbs-up. And on a related note, I used...

Go to advanced search