Wing-Loading

[Jane-DoH]

I know this might sound like a silly question, but how do airliners manage to fly reasonably well with such horrendously high wing-loadings?

[John Farley]

It is not a silly question but it is not easy to answer your post in a meaningful way without asking you for some clarification:

What is your aviation background?

What do you mean by 'fly reasonably well' (for example do you mean they have high top speeds,are controllable in turbulence, have good takeoff and landing handling characteristics etc etc)

What do you mean by 'horrendously high' (do you just mean many times that of a GA light aircraft? or something else?)

However I will offer that in general aircraft with a high wing loading will need greater distances to takeoff and land (because they will have a higher stall speed), will be more comfortable in turbulence and will not turn so tightly at low speeds as aircraft with a low wing loading.

[Abbey Road]

And for an aircraft that is hover-capable - when in the hover there is little or no aerodynamic wing-loading? ;)

:)

[Denti]

Depends if you call a helicopter an aircraft i guess ;)

[Abbey Road]

Okay, I meant (and should have specified!) hover-capable fixed-wing aircraft! ;) I have a feeling John F will know an awful lot about that.

[Denti]

I bet he does ;)

[barit1]

One can always ask the opposite question: Why do most small aircraft have such low wing loading? Their slow approach speed means that crosswind or tailwind landings are very dicey, and the large profile drag of a big wing limits their top speed. How profitable can a light transport aircraft be with its weather limitations and slow cruise speed? :8

[Jane-DoH]

John Farley,

It is not a silly question but it is not easy to answer your post in a meaningful way without asking you for some clarification:

What is your aviation background?

Aviation buff. I'm not a pilot or an aerospace engineer

What do you mean by 'fly reasonably well' (for example do you mean they have high top speeds,are controllable in turbulence, have good takeoff and landing handling characteristics etc etc)

Mostly good takeoff performance, but not just that. The other issue has to do with turning performance and such, you'd expect a plane with the wing-loading figures typically seen on a commercial-airliner (727, DC-10, etc) to lose speed much quicker than it does for it's wing-loading in turns.

I have heard about numerous cases in which relatively high g-loads were pulled (not intentionally, by accident) and while the plane lost speed in the turns, you would think that for the thrust to weight ratios an airliner has, and the heavy wing loadings, the plane would have quickly lost all it's speed and just dropped out of the sky like a brick.

What do you mean by 'horrendously high' (do you just mean many times that of a GA light aircraft? or something else?)

Well, as I understand it wing-loadings over 85 lbs/ft2.

The original 727-100 had a MTOW around 160,000 pounds and a wing-area of 1,650 square-feet, yielding a wing-loading of 96.97 lbs/ft2.

The DC-10-10 had a MTOW of 430,000 pounds and a wing-area of 3,550 square-feet, yielding a wing-loading of 121.13 lbs/ft2.

[galaxy flyer]

There are many more factors in aerodynamic design than just wing loading-- span loading (the flip side of aspect ratio), airfoil, finess ratios, thrust loading, drag, in all its components and installed high lift devices. A number of fighters have greater wing loadings than the DC-10 and perform fine, for their designed mission. Yes, under G loads they lose speed, but FAR 25 design is for 2.5 positive G and all of them possess the power to overcome the resultant induced drag.

Yes, airliners have undergone proof levels G-loadings, usually they have been associated with a deep nose-low attitude and no amount of G prior to breaking the airplane would result in a stall and "falling out of the sky".

[Jane-DoH]

galaxy flyer,

There are many more factors in aerodynamic design than just wing loading-- span loading (the flip side of aspect ratio), airfoil, finess ratios, thrust loading, drag, in all its components and installed high lift devices.

I assume by fineness-ratios you mean T/C ratio; by span-loading you mean the ratio of span to chord; and thrust loading you mean T/W ratio?

A number of fighters have greater wing loadings than the DC-10 and perform fine, for their designed mission.

Like the F-105, it performed decently well in regards to sustained agility when flying faster than a bat out of hell at low altitudes when lightly to moderately loaded; at lower speeds it bled off speed way too easily, and at full-loads, even it's high-speed agility fell off.

Yes, under G loads they lose speed, but FAR 25 design is for 2.5 positive G and all of them possess the power to overcome the resultant induced drag.

They can all hold 2.5g without loss of airspeed?

Yes, airliners have undergone proof levels G-loadings, usually they have been associated with a deep nose-low attitude and no amount of G prior to breaking the airplane would result in a stall and "falling out of the sky".

I was largely talking about while in level flight, not in a steep-dive.

[galaxy flyer]

No, span loading is weight divided by span, related to aspect ratio which is what is what you are speaking of.

Yes, fineness is T/C and thrust loading is T/W

The performance under G loads is related to specific excess power, that is, wing loading causes loss of IAS, specific excess power is how the plane can overcome the increase in induced drag. The Thud didn't have a lot of Ps at high loadings or low speed.

I cannot speak for all transport category aircraft but mostl of them at reasonable altitudes can sustain 2.5 Gs for at least 180 degrees and need no more. At cruise levels, 1.2G or 1.3 G is about standard stall margins and sufficient.

Not many transport category planes have any need to exceed 2.5 G at any time and would absolutely need to only in an out of control dive recovery.

Wing loading is not a factor in any conceivable flight regime for the types of planes we are talking about. Transports don't engage in turning fights for survival or "scissor" with another plane to get landing priority.


Were it not for these "horrendously" high wing loadings they could not do their jobs as jet transports. Try designing a jet transport with a wing loading of, say, 50 lb/ sq ft.
GF

[Pugilistic Animus]

I assume by fineness-ratios you mean T/C ratio; by span-loading you mean the ratio of span to chord; and thrust loading you mean T/W ratio?

Jane-Doh,

not exactly,
Fineness ratio, is more about the physical cleanness of the wing it concerns boundary layer T/C is the thickness ratio

Span loading, is the weight divided by the span-a measure of how much load is distributed along the span the

T/C is the thickness ratio...important when chord changes as in flap deflection

The maximum wing load or the maximum weight to ever be carried by the wing is carried at the stall...and is dependent on how far above the stall speed you are if you are at Vs then only one g can be pulled at 2Vs then four times the load will be imparted at the stall at 3Vs 9g...etc...

I hope that helps...:)

One can always ask the opposite question: Why do most small aircraft have such low wing loading? Their slow approach speed means that crosswind or tailwind landings are very dicey, and the large profile drag of a big wing limits their top speed. How profitable can a light transport aircraft be with its weather limitations and slow cruise speed? http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/nerd.gif 4th Jan 2011 07:56

Great Question:ok::}

[galaxy flyer]

I stand, actually sit, corrected by my learned colleague, PA

GF

[galaxy flyer]

PA and Jane DoH

Actually small planes have such low wing loadings due to FAR 23 limiting stall speeds to 61 knots due to crash survival considerations. Cost consideration rule out sophisticated high lift devices, hence large wing areas. Th Helio was an exception but long gone.

GF

[Pugilistic Animus]

Actually small planes have such low wing loadings due to FAR 23 limiting stall speeds to 61 knots due to crash survival considerations

GF
One learns to think differently about aviation everyday, thanks:)

[Jane-DoH]

galaxy flyer,

No, span loading is weight divided by span, related to aspect ratio which is what is what you are speaking of.

I'm sorry, I got that backwards... :}

thrust loading is T/W

Understood

The performance under G loads is related to specific excess power, that is, wing loading causes loss of IAS, specific excess power is how the plane can overcome the increase in induced drag. The Thud didn't have a lot of Ps at high loadings or low speed.

That's the energy-maneuverability formula right?

Were it not for these "horrendously" high wing loadings they could not do their jobs as jet transports. Try designing a jet transport with a wing loading of, say, 50 lb/ sq ft.

It would need to have very thin wings that were very large for it to even remotely work, though I can think of at least one proposed commercial aircraft design that had a wing-loading of 62.6 pounds/square-foot. It was called the L-2000; it was built by Lockheed as a competitor in the SST program.

In a more serious note, I assume that planes designed to sustain high g-loads (fighter-planes) are built with wings that are excessively large for what is needed for optimum efficiency in level flight?


Pugilistic Animus,

Fineness ratio, is more about the physical cleanness of the wing it concerns boundary layer T/C is the thickness ratio

Fascinating.

Span loading, is the weight divided by the span-a measure of how much load is distributed along the span

Yeah, I got span-loading and aspect-ratio backwards

T/C is the thickness ratio...important when chord changes as in flap deflection

You mean like fowler-flaps?

[John Farley]

Thanks for responding to my request.

I will not answer it directly now as subsequent posts by yourself and others have moved things on a lot further.

You clearly are familiar with a lot of aspects of aircraft design and performance but I feel have got some of the basic building blocks a bit jumbled up in your head.

I will PM you with some of the basics of lift and drag which I think might help you straighten out some of your concepts.

However all other things being equal if you literally double the wing loading of an aircraft (by filling an airliner with fuel or covering a military aircraft with bombs) then you really won’t change much beyond


The stall speed which will be 1.414 times what it was before (this will up your takeoff and landing speeds and distances)

The aircraft will have much more inertia (this will make the aircraft appear ‘sluggish’ in response to you trying to change its flight path – especially in pitch compared to the light case)

When it comes to the effects of wing loading on manoeuvre there are two aspects called the manoeuvre boundary and the thrust boundary.

The manoeuvre boundary is a measure of how much g you can momentarily pull at a particular speed (this will reduce as wing loading goes up)

The thrust boundary is a measure of how much g you can sustain without loss of airspeed and is primarily affected by the thrust available. It will suffer as you put up the wing loading but likely less than the manoeuvre boundary.

JF

[911slf]

My hang glider has 188 square feet and a wing loading less than 1.5 pound per square foot even carrying a porker like me.

It will take off at 18 mph, and will fly in a dive at 44mph. In all but the calmest conditions it requires active control inputs to avoid being thrown around like a leaf.

For a sport it's fine. As a means of transport it leaves a lot to be desired.

Reasonably????? Well?????

:)

[bearfoil]

Mine was a rogallo, and had a glide ratio of about 6:1. Its wing loading was ~ 1.75lbs/foot2, and yeah, it flew like a potato chip in a gale.

[cwatters]

Two thoughts...

1) Air pressure at sea level is around 2000 Lbs/sqft so is 85 Lbs/sqft really "high" in percentage terms (just 4%)?

2) Reynolds number. Big fast wings are more efficient than small slow ones.

Low Reynolds Number Airfoil Design (http://www.desktop.aero/appliedaero/airfoils2/lowresections.html)

[john_tullamarine]

FAR 23 limiting stall speeds to 61 knots

Originally 70mph prior to metrication.

From a discussion with an ancient engineer chap who was in the precedent organisation in the early days as a boy, 70mph was a figure plucked out of the air by the senior folk as being a reasonable starting point to put into the rule book .. and then it just stayed and was never altered.

[galaxy flyer]

J_T

Always wondered where 61 knots came from--rather odd sounding. But metrication? Perhaps, metrification or nauticalification?

GF

[john_tullamarine]

It's not really metrication, is it ? I ought to be a tad more precise at times .. have to blame the advancing decrepitude, I guess ...

(a) current rule (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid=0c28cd3127d87469135c0308dc73b53c&rgn=div8&view=text&node=14:1.0.1.3.10.2.60.8&idno=14)

(b) old FAR 23 rule (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/C67AE5AEDA8F8F5185256687006B8F49?OpenDocument) which changed to 61 kt at A/L 23-7 Sep69

(c) CAR 3 (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgCCAB.nsf/0/73377eeb0c2129fb86256dfe005fdf58/$FILE/part1.pdf) goes back to 1949 (refer 3.83). I don't have any Net references to earlier US regs but, no doubt, someone else in the sandpit will be able to cite a link to the real olden days .. 1949 - I was too young to have much of an interest in aeroplanes ..

Here endeth the useless bit of information for the day ...

[barit1]

Some pre-incarnation of CAR3 goes back to 1930s. Even racing aircraft of that era were designed to a Vso of 70 mph. :8

[Willit Run]

No wonder I can't fly an ILS; too much metriculation manoeuvreing conversion calculations !

[galaxy flyer]

Boy, am I sorry I brought this up!

GF

[Jane-DoH]

John Farley,

Thanks for responding to my request.

You're welcome

You clearly are familiar with a lot of aspects of aircraft design and performance but I feel have got some of the basic building blocks a bit jumbled up in your head.

Understood

I will PM you with some of the basics of lift and drag which I think might help you straighten out some of your concepts.

Yup, I got your message.

The stall speed which will be 1.414 times what it was before (this will up your takeoff and landing speeds and distances)

I assume that has to do with exponent in the the L = (CL)½(ρ)(S)(V^2) formula (1.414 and on is the square root of 2)?

The aircraft will have much more inertia (this will make the aircraft appear ‘sluggish’ in response to you trying to change its flight path

Yeah, more mass always equals more inertia

The manoeuvre boundary is a measure of how much g you can momentarily pull at a particular speed (this will reduce as wing loading goes up)

The maximum instantaneous g-load you could pull without getting an accelerated stall?

The thrust boundary is a measure of how much g you can sustain without loss of airspeed and is primarily affected by the thrust available. It will suffer as you put up the wing loading but likely less than the manoeuvre boundary.

Makes sense: There are planes that have good instantaneous agility and poor sustained agility.


cwatters,

Reynolds number. Big fast wings are more efficient than small slow ones.

I never knew low Reynolds numbers had any drawbacks -- I just thought they hurt you when you scaled a wing up without sharpening the leading-edge.


Willit Run,

No wonder I can't fly an ILS; too much metriculation manoeuvreing conversion calculations !

I've usually found the metric conversions fairly easy. You just have to memorize all the conversion tables. Maybe that's easier said than done, but I have most of that memorized since 7th grade.

[John Farley]

The maximum instantaneous g-load you could pull without getting an accelerated stall?

No. You will have to reach the stall otherwise how do you know you have reached the max g? DoH - sorry!

When briefing for tests to get this data the most important thing is the characteristics that the team choose to define the stall. (wing drop, buffet level, sideslip behaviour and so on)

[Jane-DoH]

John Farley,

No. You will have to reach the stall otherwise how do you know you have reached the max g?

I assume that data would have been derived from the wind-tunnel data and flight-testing...

[John Farley]

The boundaries can only be fully established by flight test.

Tunnels are just one of the estimation tools available - but estimates are just that estimates.

.

[Jane-DoH]

John Farley,

The boundaries can only be fully established by flight test.

Sorry about that...

[Jane-DoH]

galaxy flyer,

Transports don't engage in turning fights for survival or "scissor" with another plane to get landing priority.

I'm sorry, I don't even know why I'm responding but I thought that was hilarious... :ok:

[GreenKnight121]

Knots (kts) = nautical miles per hour (nmph).
1 nautical mile = 6,000 feet.

1 statute (land) mile = 5,280 feet.
MPH = statute miles per hour

1 mile = .88 nmile

None of this has anything to do with the metric system.



KPH = kilometers per hour
1 kilometer ≈ 3,281 feet ≈ .62 mile ≈ .547 nmile

[Jane-DoH]

A nautical mile is 6076 feet not 6000

[Brian Abraham]

None of this has anything to do with the metric systemThe nautical mile now days (since 1929) is actually defined in metric terms, being 1,852 metres, which in turn equates to 6,076.1155 feet.

[barit1]

Although it's conventional to think about the "metric system" in terms of metres (= 1/40,000,000 of the circumference of the Earth at the equator), today the metre is better defined, and it's all called SI (systeme internationale d'unites). I tend to think of ANY system as "a metric system".

And so the nautical mile is 1 minute of longitude at the equator, so = 1/(360x60) of the circumference of the Earth at the equator.

[Brian Abraham]

And so the nautical mile is 1 minute of longitude at the equator, so = 1/(360x60) of the circumference of the Earth at the equator.I'm afraid not barit.

The nautical mile was historically defined as a minute of arc along a meridian of the Earth, making a meridian exactly 180×60 = 10,800 historical nautical miles. It can therefore be used for approximate measures on a meridian as change of latitude on a nautical chart. The originally intended definition of the metre as 10−7 of a half-meridian arc makes the mean historical nautical mile exactly (2×107)/10,800 = 1,851.851851… historical metres. Based on the current IUGG meridian of 20,003,931.4585 (standard) metres the mean historical nautical mile is 1,852.216 m.

The historical definition differs from the length-based standard in that a minute of arc, and hence a nautical mile, is not a constant length at the surface of the Earth but gradually lengthens with increasing distance from the equator, as a corollary of the Earth's oblateness, hence the need for "mean" in the last sentence of the previous paragraph. This length equals about 1,861 metres at the poles and 1,843 metres at the Equator.

Other nations had different definitions of the nautical mile. This variety in combination with the complexity of angular measure described above along with the intrinsic uncertainty of geodetically derived units mitigated against the extant definitions in favor of a simple unit of pure length. International agreement was achieved in 1929 when the International Extraordinary Hydrographic Conference held in Monaco adopted a definition of one international nautical mile as being equal to 1,852 metres exactly, in excellent agreement (for an integer) with both the above-mentioned values of 1,851.851 historical metres and 1,852.216 standard metres.

Use of angle-based length was first suggested by E. Gunter (of Gunter's chain fame), reference: W. Waters, The Art of Navigation in England in Elizabethan and Stuart Times, ( London, 1958). During the 18th century, the relation of a mile of 6000 (geometric) feet, or a minute of arc on the earth surface had been advanced as a universal measure for land and sea. The metric Kilometre was selected to represent a centisimal minute of arc, on the same basis, with the circle divided into 400 degrees of 100 minutes.

[barit1]

Thanks for the upgrade; however MY navigation was never that precise! :O

[mike-wsm]

When getting to the seventh significant figure, do we need to consider the effect of global warming on sea level and hence on the earth's circumference? Or the fact that aeronautical miles are longer because the earth's circumference is greater when at altitude?

[Jane-DoH]

mike-wsm,

Very good observation about the distances being greater at altitude. If you drew a line 30,000 feet up in the air at your takeoff and landing points you technically cover a little bit more distance than if you were at sea-level the whole time.

[john_tullamarine]

which in turn equates to 6,076.1155 feet

I just love it when people talk in tongues ...

[Upper Air]

Very good observation about the distances being greater at altitude. If you drew a line 30,000 feet up in the air at your takeoff and landing points you technically cover a little bit more distance than if you were at sea-level the whole time.

Is that maybe why when they fly from LON to NY say, and take aboard an atomic clock and then say, that they have gained or lost x minutes of time, and then start to assume that in travelling from A to B one`s body/time/zone. . . /thing slows down or speeds up. . ?

Its funny how they never calc the angle at altitude thus increasing the ground distance (experiemnt) take two small knitting needles, one large orange, place the knitting needles in the orange like a pair of alien type antennae splaying apart from the centre at approx 20 degrees offcentre (you might be better using the sine from the suraface of the Earth, or not . .) - voila! dist between needles at the suraface of the orange is x and the dist between the two needles at altitude above the orange (i.e., at the ends of the needles) is greater.

So. . . .to go from a to b at altitude will take longer even though the distance is 2geographically the same but it is not the same from a Spherical Geometric point of view. ( I bull---t) Except that the distance at altititude is further than at the surface, this is NOT bull---t and all the navigation caluclations are based on measuremnt on the surface.

That is why they think your time/clock alters when you travel and that time slows down or speeds up. . . ah well, these are probably the same people that believe in the displacement theory.

Sorry, I, I just had to share that with you guys, its Jane, she has inspired me to be a scientist - I think she is building either a new ICBM or alternately a new space craft which needs little fuel.

[Jane-DoH]

Upper Air

Technically, the fact that you cover a slightly greater distance up at altitude, then running right along the surface of the earth would slightly increase the effects of jet-lag when you're going from east to west, and slightly reduce the effect of jet-lag when you're going west to east.

I think she is building either a new ICBM or alternately a new space craft which needs little fuel.

Ya got me! I'm building me a spaceship! Rather than moving around the universe, it moves the universe around the ship :}

[DERG]

Robyn..the last idea is classified. Best move on.

[Jane-DoH]

DERG

Robyn..the last idea is classified. Best move on.

Understood

[sevenstrokeroll]

if anyone would like to see how wing loading tests were originally done, find the movie, "China Clipper" and watch how they put sand bags on the wings until they (the wings) break.

caaaraaachk

[barit1]

sevenstrokeroll:

Nope. You're describing the ultimate load structural test. No aerodynamics anywhere in sight. An aircraft can have great structural strength but terrible flight performance (or vice versa...).

[sevenstrokeroll]

yup...you are right...but its really cool

[HazelNuts39]

No aerodynamics anywhere in sight.No ? I thought the sandbags simulate aerodynamic loads.

regards,
HN39

[DERG]

Robyn

If you look at a video on youtube of the B787 testing ...as the 'plane rotates..ahem..takes off from the ground you see the wings BEND.

It is though like a toy with invisible strings: pulls the whole mass, prolly 300 tonnes, pulled up by the wing tips. Do you agree?

Now I make that 150 tonnes per wing. The wing area is more near the "root" where the wing comes out of the fuselage, so there it is really strong. Then at the end where the winglets are, it is delicate and I guess that is why it bends more.

Then we have all the other wing shapes too...like the old Delta wings on our V bombers here in the UK and same as Concorde. I am sure they did bend a little but nothing like we see now with the B787 or the A380 or that huge Antolov Russian transport 'plane.. Do you agree?

Regards

[Jane-DoH]

DERG

If you look at a video on youtube of the B787 testing ...as the 'plane rotates..ahem..takes off from the ground you see the wings BEND.

Yes, that's because the fuselage doesn't produce any significant lift so it weighs down the mid-section of the plane, the wings on the other hand are lifting so you get a bend. The wing gets progressively more flexible at the tips so you get more flexing there.

Then we have all the other wing shapes too...like the old Delta wings on our V bombers here in the UK and same as Concorde.

A delta is a naturally more rigid structure than a swept wing as I understand it. I think it has something to do with the fact that by having no trailing edge aft sweep you naturally get less flexing because more of the overall wing's chord connects to the fuselage.

I am sure they did bend a little but nothing like we see now with the B787 or the A380 or that huge Antolov Russian transport 'plane.. Do you agree?

Most larger spans flex more than smaller ones; also most modern airliners use composites much more frequently in the design. They can flex more than metals can and maintain structural integrity if I recall.

[mike-wsm]

Just went through the process of logging in and getting back here, now what was it I wanted to say? Old age y'know. Shouldn't be allowed but I don't care much for the alternative.

Oh, yes. I think bendywings are affected by national history. During the thirties there were some wing failures on British projects, and people tried to make the wings much stronger, confusing this, as drawing offices will, with making them more rigid. Bristols ended up with the extremely rigid Pollicut wing that was used in everything, Bombay, Britain First, Blenheim, Beaufighter, Bolingbroke, Beaufort, Buckingham, Buckmaster, Brigand, Freighter, Wayfarer to name the ones that sprng readily to mind. Avros did much the same in the Vulcan, and I don't recall the Comet, Valiant or Victor being particularly flexible. It was Boeing, after a visit to Bristols, who had the bright idea of making the wing flex along its length whilst importantly maintaining its torsional rigidity, mostly, but allowing the big forward masses, aka engines, to twist the wing for gust alleviation, which was what Bristols were doing by a different method when they visited and saw the Brabazon alleviator, which so far as I know never worked in flight.

[Pugilistic Animus]

Jane-Doh

you really love planes...I'm surprised you never had any flight training-nice to see :)

[rooaaiast]

Mike-wsm
I never thought about the natural wing-twist natural gust alleviation movement. Of low-slung engines.
You learn something every day......Thanks

[Jane-DoH]

mike-wsm

It was Boeing, after a visit to Bristols, who had the bright idea of making the wing flex along its length whilst importantly maintaining its torsional rigidity, mostly, but allowing the big forward masses, aka engines, to twist the wing for gust alleviation

I didn't know the engine pods were used to twist the wing leading-edge down in responses to gusts. I just thought the engines weighed the wings down so they wouldn't flex up as much.

[barit1]

Mass-balanced control surfaces have been an aeronautical design feature for eight decades - maybe more. It provides dynamic stability, more flutter margin.

Mounting engines ahead of the flexible wing, on pylons, is no different in principle.

[mike-wsm]

Mass-balanced control surfaces have been an aeronautical design feature for eight decades - maybe more. It provides dynamic stability, more flutter margin.


Er, rather more than eight decades, more like 250 million years, the mesozoic Pterodactyl had an aerodynamic and mass balance behind its head to allow it to move its beak sideways in flight.


http://sexypterodactyl.files.wordpress.com/2010/06/sexypterodactyl_fly.jpg

[barit1]

I stand corrected. :D:O

[HarryMann]

I think there were others (than Boeing) well aware of nodal placement of masses, torsional gust alleviation etc in the 50's and 60's.

[barit1]

An interesting sidelight: When Boeing initially proposed a 707-based AWACS airframe, new engines were proposed: more efficient, lighter weight, etc. Boeing was concerned that if they were TOO light, ballast would be needed to insure dynamic stability.

In the end, they reverted to the tried and true JT3D/TF33. That is, until the CFM56 retrofit came along.

[bearfoil]

The Pterodactyl was not strictly speaking, a flyer. It could not take off, but had to find a cliff or hill to launch from, to soar. Those finger thingies at the LE joint are graspers to climb with. The Alien Head helped reduce drag. Launch, hike, Launch, hike, Launch hike, etc. Kinda like hang gliding.

[mike-wsm]

Plenty of hang glider flyers use the same site for takeoff and landing, it's called slope soaring. And when they're airborne they seem to think they're flying.

Many birds use slope soaring, a gull rarely flaps its wings except for t.o. and l., and uses cliffs and seashore features to gain height. Pelicans seem to fly all day in line-ahead formation using wave soaring. Glorious to watch the whole formation wing over one by one from one wave to the next.


http://msnbcmedia3.msn.com/j/MSNBC/Components/Photo/_new/tiny-pterodactyl-278x225.grid-6x2.jpg

Pteraichnus nipponensis (http://www.msnbc.msn.com/id/35646571/ns/technology_and_science-science/)


I somehow think a pterodactyl would be a little vulnerable when hiking and would prefer to return to base by air. Good energy management would permit excursions to lower levels and return to base. Dunno what they used to feed on, could they catch 'insectosaurs' in midair or did they grab ground-based food?

[Jane-DoH]

mike-wsm

"Insectosaurs"? Last I checked arthropods were around way before reptiles were -- they were just insects.

[mike-wsm]

Yes, and ptera nippo appears to be eating one!

[Jane-DoH]

I love my arthropods too, crustaceans in particular -- usually get 'em at a seafood restaurant. They go great with butter.

[sevenstrokeroll]

http://www.jaunted.com/files/6193/HughesAirways.jpg

[bubbers44]

I remember those days. Hughes Air West, PSA and Air California with a crew of hotties. The trouble is they are still flying and the only requirement is to fit through the window exit.

[Jane-DoH]

mike-wsm

I just thought of something. The earth is not a perfect sphere, it's diameter and circumference across the equator is larger than the poles which has to do with the earth's rotation.

Regardless to compute the differences of altitude you'd take the planet's circumference, which is pretty easy to compute (πD); you'd take the planet's circumference at altitude ([D+2(Altitude)]π); then divide the circumference of the planet at altitude by the circumference of the planet at sea-level.

At that point you multiple that number by the length of your trip.

Circumference of Earth at Sea Level (Across Equator) = 40,075 kilometers
Altitude of 35,000 feet = 11,000 meters
Altitude of 60,000 feet = 18,288 meters
Circumference of Earth at 11 kilometers = 40,144 kilometers
Difference in Circumference @ 11 kilometers = 69 km
Circumference of Earth at 18.288 km = 40,187 kilometers
Difference in Circumference @ 18,288 meters = 112 km

So theoretically, for a flight that would traverse 10,000 km on the ground right along the equator, you would travel about 10,017.22 kilometers by air if you were flying at 35,000 feet; and 10,027.95 kilometers if you were at 60,000 feet. Of course this is theoretical because you'd have to take off, climb to altitude, then descend; you would also have to fly right along the equator with no deviation (no northwest/northeast/southwest/southeast); to make it even more complex many airports are not at sea-level, and flights usually don't involve a constant climb and descent rate.