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Position of wings


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#1 PMN1

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Posted 01 May 2004 - 08:56 PM

Different bomber designs had different positioning of their wings - high wing, mid wing or low wing.

Does one design have advantages/disadvantages over the others?


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#2 B-24WillowRun

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Posted 02 May 2004 - 01:02 AM

The higher wing positions say like the B-24:D alow for a clearer bomb bay and I think a stronger wing. ;)

#3 andyo2000

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Posted 03 May 2004 - 09:37 PM

I believe lower wings made for much better maneuverability, and I think there was a slight increase in speed and stability as a gun platform as well. But that's for fighters, so it might not affect bombers, especially the gun platform stability as a bigger aircraft needs less stability to absorb recoil.

#4 GregP

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Posted 04 May 2004 - 08:27 AM

Interesting observations. There is no "advantage" to any wing position other than it is probably less draggy if the wing is attatched to the fuselage rather than being mounted above or below and attached with struts.

Low wing, mid-wing, or shoulder wing do NOT indicate the strength of the wing. The design of the wing spar and the strength of the structure dictate the g-loading a wing can take.

If you mount the wing in a shoulder position, then the mass of the bomber lies mostly below the wing, and the wing needs less dihedral to be stable. If you mount the wing in a low position, then it needs MORE dihedral to achieve the same stability. A mid-wing needs less dihedral than a low wing, but more than a shoulder wing for the same stability. Too much dihedral means the aircraft will not achieve a fast rate of roll.

The Hellcat suffered from this very weakness.

There are other design considerations.

A low wing means a short landing gear whereas a high wing needs a longer gear strut to achieve the same strength and ridgidity. When the strut is longer, it can generate more torque when landing, so the attachment structure must also be stronger (read that as heavier).

Any aircraft is a design compromise since aopimizing one facet of an aircraft's performance affects other areas of performance.

The lowest drag is a well streamlined, and well-filleted mid-wing. But ... they are harder to manufacture. If you want to see the ultimate in this area, check out the Republic XF-12. It weighed in around 46,000 kg and could go over 740 kph! Almost in the early jet speed range.

The best wing planform is elliptical. The best example of this is the Supermarine Spitfire. But, a tapered wing is ALMOST as good. The P-51, Zero, and Bf 109 had tapered wings. In the end, the Spit was probably the best fighter (not intended to start another best fighter thread) due to the fact that Reginald Mitchell optimized the wing first, and compromised after that. One of his compromizes was ... fuel! The Spit was mostly a short-legged beast, but flew wonderfully while the airscrew was turning under its own power.

So ... the realk answer is:

Wing design is a compromise, and there are many ways to do the same job. None are the best at everything, but many are very good at a lot of things. The designer must choose what wing planform and configuration best suits the design objectives he is working with, and he compromises everything else to a degree after he makes that choice. But ... only the chief designer makes the number one choice ... the wing.

#5 B-24WillowRun

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Posted 05 May 2004 - 05:44 AM

GregP, that was great post!!;)

I was thinking of the Davis wing on the B-24 and Coronado that is sholder mounted and thin. It was designed for long legs but had its own problums. I must agree with you that design is really compromise and what you want to center on first as most important.

As for the eliptical wings they are good for Props, but jets seem to lag a bit. But that is a hole nother topic. No bother with the Spit coment, it was an example for our betterment.[^]

#6 GregP

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Posted 05 May 2004 - 08:58 AM

Another interesting observation about elliptical wings and jets. B-24WillowRun is right, most jets do NOT have elliptical wings. This is mostly due to the speed at which they are expected to fly.'

If there were a jet designed for 400 to 550 mph, then an elliptical wing would be a really neat choice. Something like the Fairchild A-10 comes to mind. Unfortunately, elliptical wings do NOT lend themselves to efficient construction, so tapered wings are the norm.

If the speed goes above 550 mph, then the wings all start to get swept to help with high-speed aerodynamics. This can be reasdily seen in the French Arsenal VG-70 and VG-90, the last projects by Vernisse and Galtier (VG).

The closest thing I can think of to an elliptical wing in a jet is the Gloster Meteor III. The tapers almost form an elliptical wing, and it falls right in the speed range above at just under 500 mph. Another potential candidate was the WWII German Heinkel He-280. The leading edge was straight, but the trailing edge was elliptical. It was slightly faster at 544 mph, but right in the ballpark.

The French SNCAC NC 1071 MIGHT have an elliptical wing, but I can't find a plan-view of it, so I only suspect it to be so.

The French Sud Ouest 6000 and 6020 might be close to elliptical also, but they appear to be tapered when you look closely.

I can't think of anything else that even MIGHT be a jet example of an elliptical wing, so I suppose we can conclude that high-speed and ease of manufacturing in a jet are more important than aerodynamic considerations.

#7 PMN1

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Posted 05 May 2004 - 10:30 PM

Was the wing designed first and the fuselage around it to meet requirements?

#8 B-24WillowRun

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Posted 06 May 2004 - 04:49 AM

GregP, great! But the speed thing with a jet is more because of the buffiting that you get as speed aproches the sound barrier. The P-38 had that problum when it would dive.

As for the A-10's design, it is one of my favorate jets and would have been at home in WWII, say the Eastern front. It is infact named after the P-47 ;)

My take on design of wing or set specs, it is all what the designers want. US makers go for function then form.

#9 GregP

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Posted 06 May 2004 - 08:28 AM

Hi WillowRun,

True, form instead of function.

I sometimes fly full scale aircraft (Cessnas and Pipers), but have flown radio controll airplanes for over 25 years off and on. I had one model with a completely elliptical wing ... even more pure elliptical than a Spitfire.

It flew absolutely great. So, based on THAT experience, I'd like to see a full-scale plane with a true elliptical wing. Too bad they're so hard to make!

It is also interesting to note that the Lockheed P-38 had a problem with near-sonic flight, but WAS recoverable if the pilot used the trim tabs to do it. The trim tab could move the elevator despite the shock wave ... it was considewrably stronger than the human-powered elevator. Some P-38s were fitted with dive recovery flaps. They changed the center of lift, moving it forward and resulting in a nose-up moment of force.

#10 robert

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Posted 07 May 2004 - 01:46 PM

I've always loved the shape of the Heinkel He 112 wing:

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#11 JoeB

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Posted 07 May 2004 - 10:33 PM

Another aspect in WWII prop types, esp. fighters, is a low wing allowed a larger propeller diameter for a given length of landing gear legs. In general momentum theory of prop efficiency will favor putting a given HP through a larger prop disk. And very long gear legs added weight and complexity (to stow them). Hence some went beyond low wing to inverted gull wing, as in drawing of Heinkel above, and the F4U.

And interesting study of relative merits of wing placement is the Kawanishi Shiden ("George"). The original design was the N1K Kyofu (Rex) floatplane fighter with a mid wing, presumably found optimum for aerodynamic reasons. The initial landplane adaptation, N1K1-J, retained that arrangement with complex contracting gear legs. Definitive N1K2-J Shiden-Kai was redesigned with low wing and simplified shorter gear legs.

Joe

#12 simon

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Posted 07 May 2004 - 11:38 PM

Unless you opt for an extremely narrow landing gear, like the Bf109, but in the latter case your storing up all kinds of problems if for some reason you have to start cutting corners on pilot training!

#13 GregP

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Posted 09 May 2004 - 11:14 AM

One thing I always wondered about the He 112 was about the shape of the horizontal tail. Since the wing was very elliptical, why wasn't the tailplane?

Just curious.

I believe the He 112 was as good as the Bf 109 and would have been able to be developed into a great fighter, just as the Bf 109 was.

#14 Corsarius

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Posted 09 May 2004 - 02:30 PM

Great post earlier, GregP. I'll follow that one to the letter. I've nothing to contribute there as you've pretty much said it all.

Otherwise, my favourite position on the wings? On either side of the aircraft is a firm favourite of mine.

#15 simon

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Posted 09 May 2004 - 02:51 PM

You say that like it's the only option! Some aircraft did carry their wing above them, although I can't stand the appearance of the parasol monoplanes myself!

#16 robert

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Posted 09 May 2004 - 04:43 PM

quote:Originally posted by GregP

One thing I always wondered about the He 112 was about the shape of the horizontal tail. Since the wing was very elliptical, why wasn't the tailplane?

Just curious.


A good question - I don't know the answer! One interesting thing is that the He 112 was, of course, completely redesigned before it got to the definitive He 112B version, and the prototype He 112 V1's tailplane was far more of an elliptical shape than the later version.

#17 GregP

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Posted 10 May 2004 - 12:48 PM

They SAY that an airplane that LOOKS right, FLIES right.

If they're talking about the Spitfire, the P-51, the Yak-3, the Zero, the Fw 190, or the Bf 109, then they're RIGHT, and in spades.

These planes just LOOK right. Of these, I believe the Spitfire looks the part the best of all. It has the almost-ideal elliptical wings and tail.

But, that's just personal opinion.The He 100 looked awesome, but they elected not to build it. Go figure.

#18 Corsarius

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Posted 10 May 2004 - 02:23 PM

yes. Parasol monoplanes just don't look right. I don't care how good the Fokker DVIII was supposed to be in WWI.. I just wouldn't feel comfortable flying in one.

Thinking of which, there was a third aircraft that vied against the He112 and Bf109 for the new Luftwaffe fighter. It was by Focke-wulf, the FW159. A parasol monoplane with retractable undercarriage. Seriously, could you REALLY see these things engaging spitfires over britain? In fact, I'd almost put that one in the 'ugliest fighter' thread.

#19 PMN1

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Posted 11 May 2004 - 12:50 AM

Depending on where you read it, the Lancaster is given a ceiling of around 23,000ft - 25,000ft while the Lincoln is given a ceiling of around 28,000ft - 30,000ft.

Was the Lincoln's greater ceiling due to the more powerful engines or did the longer wingspan (102 vs 102ft) have a part in this (bearing in mind the fuselage length and weight of aircraft also went up)?

Could the Lancaster and Halifax have been given ceilings to match the B17 and B24 with the Merlin (Lancaster) and Hercules (Halifax) engines they used?

#20 B-24WillowRun

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Posted 11 May 2004 - 01:18 AM

GregP, I agree with the P-38's trim tabs and dive breaks. Sorry i was gone so long in reading this forum. As for this He-112 stuff the number say it was a good airftaft, but it just lost out to the 109 in that the 109 in my thoughts was already in production. Please corect that if it is wrong, I have not checked that. ;)

As for the inverted gull wing why not use it? It dose make some very pritty big engine fighters, but wasent it harder to land?[?]




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