Hobo Jungle

[MurphOnMillerAve]

...porcine pilots plummeting?
(Couldn't resist the alliteration potential.)

[sarge]

Sorry, I'm not getting the relevance of the NASA expose on how lift really is generated vs. the "myths", to your thesis that area is irrelevant to capacity. Wing loading is all great but you neglect velocity required against that loading and the idea area is a variable as are its components (span times chord).

I seem to remember the loaded weight divided by wing area gives wing loading. That wing loading set against the velocity (something exponential like 1/2V squared) along with air density and a lift coefficient (which is where you appear to be lurking) gives one lifting force. Very simplistically the higher the speed the greater the lifting force generated for a fixed weight and area, or for Murph's question about a human doing bird-flight like our owl, to achieve a lifting force to simplistically counteract a known loaded weight at a bird-speed, area then becomes the principle variable since birds tend to max out at something like 5lbs/sq ft wing-loading. Let's call density fixed and your lift coefficient must be in there.

Unless things have radically changed, I seem to remember area matters in defining a required lifting force as does (greatly) velocity.

Unless I'm missing something and am steeped in myth (which is quite possible), the list of variables must include velocity, air-density, a lift coefficient, loaded weight, and chord all needing defined with respect to each other before you solve for (Murph's question) a wingspan.

I can be thick as hell, though...

[webenda]

I tried to keep it simple by comparing wingspans of birds vs weight and extrapolating wingspan for a 250 lb bird. Murph asked for wingspan, Murph got wingspan. Now Sarge, you are making the problem/answer more interesting/fun.

Sorry, I'm not getting the relevance of the NASA expose on how lift really is generated vs. the "myths", to your thesis that area is irrelevant to capacity.).

I don’t recall saying, “…area is irrelevant to capacity.”
I used the word, “capacity” in referring to the C-5A Galaxy.

While I was at Lockheed Aircraft I overheard the engineers talking about how the C-5 Galaxy did not fit the usual formulas for aircraft design. They were puzzled and delighted to find it had a much larger load capacity than predicted. Seems the bigger the flying machine, the better its load lifting efficiency.

Nothing there about the C-5A’s 6,200 ft2 wing area being irrelevant. Nowhere else is “capacity” mentioned.

We can compare wing loading on the 28 foot span 10 foot chord and 1 inch chord wings.
250 / (28 x 10) = 0.9 lbs/sq ft
250 / (28 x 1/12) = 107 lbs/sq ft

At that wing loading (107 lbs/sq ft) a half inch chord wing is going to have flow separation on top of the wing and stall. A longer chord is needed to gently direct the air from stationary to a downward vector. Simple theory does not consider air does not like to be treated rudely.

Now if we made that 1 inch chord wing 3,333 feet in span it would have way too much lift at the same angle of attack so we will have to reduce the angle of attack to almost nothing. Now the air will kindly flow over the wing, produce 250 pounds of lift at a wing loading of 0.9 lbs/sq ft and everyone will be happy.

Well, maybe not everyone. Not even a carbon fiber wing would be rigid enough to maintain a reasonably straight wing span wise . And there is even a problem at 28 foot span with torsional rigidity.

Those are just some of the reasons extremely short chords are seldom seen.

You might have meant, “I'm not getting the relevance of the NASA expose on how lift really is generated vs. the "myths", to your thesis that chord is irrelevant to lift.”?

I'll work on the answer to that question. I am somewhat fuzzy on where I got that information. Thought it was NASA.

[sarge]

I don’t recall saying, “…area is irrelevant to capacity.”

Well, yeah you did here when you said:

Actually, Wingspan is the only defining factor in calculating an ability to generate enough lift to fly 250lbs.

I think we're talking cross purposes here and still missing the point. The point is simply I don't buy that wingspan itself is the only defining factor to calculate the ability to lift a defined load; total loaded weight, velocity, wing area, air density, and the lift coefficient all come into play in what was a traditional aero calc. They are all defining factors.

[webenda]

OK. I'll see what I can do starting with this equation.

Equation for the Wrong Theory of Lift.png (16.63 KiB) Viewed 1871 times

[sarge]

OK. Go for it.

Understand though I'm still in need of convincing you can confidently give a Murph a wingspan with no other parametres defined:

Given the average size and weight of us, can you imagine what the wing-span would have to be for us to have natural flight, if we had wings.

You and I? I like that you ask the easy questions. Answer: 28 ft wing span.

And assert:

Actually, Wingspan is the only defining factor in calculating an ability to generate enough lift to fly 250lbs.

...when controlled sustained flight is demonstrated by Yves Rossy crossing the Channel "wearing" a fixed-wing aircraft with an 8' span, Fritz Ungar's fixed-wing pack has an 11' span, just to cite a few examples with considerably shorter wingspans than the original post (and apparently the formula you chose) would assert.

[webenda]

You mention some spans for human flight wings. The span gives a clue about take off speed.

Yves Rossy: 8 feet.
Yves launches into flight from a helicopter, flys at 186 mph and lands with a parachute.

Fritz Unger: 11 feet
Fritz had planed to take off from the ground thus longer wingspan so he could take off at less than his predicted flight speed of 200 mph. With a wing loading of 13 lbs/sq foot he should have been able to take off at ~40 mph. He did manage 2 inch altitude at 40 in one of his videos.

Fritz's wing design was unstable in pitch and yaw . You can see it was unstable just by looking at it--no reflex and no sweep back or vertical stabilizer. Frizt seems to have disappeared at the end of 2013. I have been searching for "Fritz Unger Obiturary," but can't find it. Maybe he is still alive but unable to post on the internet anymore.

Murph the Angel: 28 feet
Long wing span and maybe a little head wind allows Murph to take off just by running a few steps. Sort of like this:=> https://youtu.be/L7LmuweBQlA
Landing at zero speed possible with headwind.

33 440

[sarge]

Yves Rossy: 8 feet.
Yves launches into flight from a helicopter, flys at 186 mph and lands with a parachute.

Actually, Wingspan is the only defining factor in calculating an ability to generate enough lift to fly 250lbs.

Not surprised since he cannot run at take-off or landing speeds. Flying the Channel, he is controlled and sustainable in flight. Looks like velocity (for one of several) is a defining factor after all.

Given the average size and weight of us, can you imagine what the wing-span would have to be for us to have natural flight, if we had wings.

You and I? I like that you ask the easy questions. Answer: 28 ft wing span.

It also looks like a calc for wingspan without the other factors defined is overly simplistic at best.

After three days, I remain unconvinced that wingspan is the only defining factor in calc'ing the ability to generate enough lift to fly 250lbs, nor does the empirical evidence support the notion the calc you are using, such that your answer is a definitive 28 feet, is correct.

Shall we move on as disagreeing friends, then?

[Rufus T. Firefly]

I am aware that with sufficient applied thrust that a pig can be surprising aerodynamic.......however landing does tend to generate bacon and good BBQ.

[webenda]

Shall we move on as disagreeing friends, then?

Page four of NASA's Incorrect Theory series states, Arguments arise because people over-simplify the description of the problem of aerodynamic lift.The real details of how an object generates lift are very complex and do not lend themselves to simplification.

I am not finished but this jungle can move on to other topics. I will be back with a simplified explanation of why the lift formula that has been used since the Wright Bro's. is incorrect and lift does not depend on wing area.

Reference to Wright Bro's: http://wright.nasa.gov/airplane/liftold.html

[sarge]

...which isn't the question.

The question remains how wingspan is the "only defining factor", and a 28' span is a believable answer to some formula as required to lift a Murph, when history has many examples that fly in the face of that; an F104G only has about 22' span lifting a loaded weight equal to some 80 Murphs.

I am waiting for the expose sometime, though. We often forget fundamentals continue to change even after we retire.

I'm with you; on to different topics!

[webenda]

The F104G's official top speed is 1,328 mph. At that speed air is not compressible. At that speed the F104G does not need wings.

The F104G wings are needed for takeoff. Takeoff speed for an F104G is 219 mph. Your MG Midget has enough bonnet span to takeoff at that speed.

I suspect Murph cannot run 219 mph. [opinion] Considering what his top speed might be, he is going to need every inch of those 28 foot span angel wings to takeoff.

Please criticize yourself for comparing Murph to an F104G.

I notice you keep bringing up speed. I won't leave speed out. The small "a" in L=ma stands for acceleration, which is a function of air speed in a wind tunnel or aircraft speed in the real world.

[sarge]

The F104G's official top speed is 1,328 mph. At that speed air is not compressible. At that speed the F104G does not need wings.

True, but again an obfuscation, for:

The F104G wings are needed for takeoff. Takeoff speed for an F104G is 219 mph. Your MG Midget has enough bonnet span to takeoff at that speed.

So 21 feet can lift 80 Murphs in controlled sustainable flight, disproving the assertions of your calc and that wingspan is the only defining factor. Simples.

I notice you keep bringing up speed. I won't leave speed out. The small "a" in L=ma stands for acceleration, which is a function of air speed in a wind tunnel or aircraft speed in the real world.

Yes I will, at least the velocity component of acceleration, along with density of the air, some derivation of a lift coefficient, total loaded weight, and wing area (the last at least until I can let go the old ways and accept some new parameter based on the NASA argument), all factors needing defined.

As always, F=ma.

Please criticize yourself for comparing Murph to an F104G.

A fair cop, mate, but still better than comparing him to a C130 or a C5.

Enough of this! Lets move on to something else. The rest of the world...

[rogruth]

The look in the cats eyes is sort of smiling but the mouth is saying "Don't you dare touch my post or me".
Nice kitty.

[sarge]

Actually one of those lucky shots with my little point-n-pray Canon that sits on the table next to my chair, one of those yawns that could be enjoyed by everyone in the room.