CoolGuy
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How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 2:50 am

Of course it has a shape that seeks to lessen drag to the best extent possible, but does the fuselage of an aircraft provide any lift? My guess is yes to a small degree.
 
EMBQA
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RE: How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 3:13 am

Quoting CoolGuy (Thread starter):
Does the fuselage of an aircraft provide any lift?

No... they do not offer an airfoil to provide the lift. I think only on the Shorts 330/360 does.... I was told it was as much as 20%.
"It's not the size of the dog in the fight, but the size of the fight in the dog"
 
hotelmode
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RE: How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 3:21 am

It Doesnt need to be an aerofoil to create at least some lift. Any angle of attack to the airflow above 0 will cause an upward force and if the journey for the air over the top is longer than that underneath again "some" lift will be created. The 747's upper deck for example creates some lift. Insignificant compared to the wing of course but it is there.
 
CoolGuy
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RE: How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 3:21 am

Any shape that cuts through the air will provide lift in one direction (or none if the shape is just right). Since the top sides of aircraft seem to be more curved than the bottom, that should provide some lift (and some substantial but necessary drag).


Edit: Hotelmode, you beat me to it. I just wonder how significant or insignificant that amount is.

[Edited 2007-08-02 20:23:58]
 
aeroweanie
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RE: How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 3:37 am

I happen to have a Beech Super King Air 200 CFD solution open on my computer right now. It says that the wings are carrying 80.4% of the total lift, the horizontal tail is carrying a download that is -.2% of the total lift, the nacelles (including overwing portion) are carrying 9.5% of the total lift, the vertical tail (including the bullet fairing at the top) is carrying .3% of the total lift and the fuselage is carrying the remaining 10% of the total lift. The fuselage needs to carry some lift, otherwise you won't have any lift carry-over and the induced drag will be high.
 
hotelmode
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RE: How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 3:52 am

Quoting CoolGuy (Reply 3):
Edit: Hotelmode, you beat me to it. I just wonder how significant or insignificant that amount is.

I dont know, I currently fly the pax 747-400, one of my friends is now on the freighters (short upper deck) and claims there's a small but discernable difference in aircraft behaviour especially at low speed. I would be interested to see if the trim postion for an identical load distribution is different on the freighters.
 
9VSIO
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RE: How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 4:05 am

Don't some aerobatic aircraft have fuselages that are shaped like aerofoils to provide lift when the bank angle is around 90? Or is that just a myth?
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2H4
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RE: How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 5:03 am

Quoting AeroWeanie (Reply 4):
I happen to have a Beech Super King Air 200 CFD solution open on my computer right now.

Do you have any examples from other aircraft? What do you think the Shorts 330/360 would be?

Quoting Hotelmode (Reply 5):
I would be interested to see if the trim postion for an identical load distribution is different on the freighters.

Me too. The freighter has a shorter hump, so it seems logical that there would be some difference....


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lowrider
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RE: How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 10:45 am

Quoting 2H4 (Reply 7):
What do you think the Shorts 330/360 would be?

I have heard figures of 20 to 25 percent as well. The struts and gear fairings provide about another 10 percent.
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tdscanuck
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RE: How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 6:35 pm

Quoting CoolGuy (Reply 3):
Since the top sides of aircraft seem to be more curved than the bottom, that should provide some lift (and some substantial but necessary drag).

Even if the fuselage was symmetric you'd still get some lift, at least on airliners, because virtually all of them cruise with a few degrees of nose-up pitch.

If you happen to get some lift form the fuselage it's an OK bonus, but it's not really a good idea to design for it. The wing is far more efficient at producing lift than the fuselage; you want to get as much lift there as you can.

Tom.
 
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Jetlagged
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RE: How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 8:11 pm

The fuselage does create lift (and sideforce). Particularly true for missiles, where a large proportion of lift comes from the body (some only have small control fins at the rear).

Quoting Hotelmode (Reply 5):
I dont know, I currently fly the pax 747-400, one of my friends is now on the freighters (short upper deck) and claims there's a small but discernable difference in aircraft behaviour especially at low speed. I would be interested to see if the trim postion for an identical load distribution is different on the freighters.

Possibly, but the aerodynamic differences between 747-400 and 747-400F do not begin to appear until about Mach 0.6 and above (according to Boeing). Just as likely to be a difference in behaviour due to the different inertia with main deck cargo.
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britjap
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RE: How Much Lift Does The Fuselage Provide?

Fri Aug 03, 2007 9:44 pm

As others mentioned the fuselage certainly does generate some lift.

At this years Paris air show the C-27 gave an awesome display involving at one point a pass during which it was banked at a crazily high angle. The commentator mentioned that during this manoeuvre the aircraft was generating a lot of its lift from the fuselage.
 
Stil
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RE: How Much Lift Does The Fuselage Provide?

Sat Aug 04, 2007 12:20 am

Well, if there's some condensation over the fuselage, there should be some low pressure and some lifting


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Stil
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F27Friendship
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RE: How Much Lift Does The Fuselage Provide?

Sat Aug 04, 2007 1:18 am

Quoting CoolGuy (Thread starter):
Of course it has a shape that seeks to lessen drag to the best extent possible, but does the fuselage of an aircraft provide any lift? My guess is yes to a small degree.

This depends ofcourse on the aircraft type and tyhe conditions. As said,under an angle most normal fuselages provide some lift.

The Shorts SC.7 Skyvan partially uses the lifting body principle as the fuselage generates 30% of the lift.

A lot of fighters have a lifting fuselage incorporated in the design, like the F-16
 
aeroweanie
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RE: How Much Lift Does The Fuselage Provide?

Sat Aug 04, 2007 10:05 am

Quoting 2H4 (Reply 7):
What do you think the Shorts 330/360 would be?

I don't know. I have the geometry, but have never built a CFD model. Someday....

Quoting 2H4 (Reply 7):
Do you have any examples from other aircraft?

747:
Wings: 89.5%
Fuselage: 13.1%
Horizontal Tail: -3.7%
Vertical Tail: .1%
Nacelles and Pylons: 1%

P-51D:
Wings: 92.9%
Fuselage: 7.7%
Horizontal Tail: -.7%
Vertical Tail: .1%
 
2H4
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RE: How Much Lift Does The Fuselage Provide?

Sat Aug 04, 2007 11:51 pm

Boy, it sure would be interesting to see the numbers for the F-104, what with those tiny playing cards wings...

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N231YE
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RE: How Much Lift Does The Fuselage Provide?

Sun Aug 05, 2007 11:09 am

Take a look at a photo of the old F-14. Note how its fuselage has an airfoil shape to it.

I was once told that by a ex-Navy mechanic, whom stated that the F-14's fuselage provides a substantial amount of lift...it in conjunction with the swing wing, gave the F-14 awesome low-speed handling characteristics.
 
9VSIO
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RE: How Much Lift Does The Fuselage Provide?

Sun Aug 05, 2007 6:32 pm

Don't forget the story of the F-15 that made it home with only one wing!
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FredT
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RE: How Much Lift Does The Fuselage Provide?

Sun Aug 05, 2007 8:52 pm

Quoting Hotelmode (Reply 2):
if the journey for the air over the top is longer than that underneath again "some" lift will be created

There's four often given explanations for lift. Two are true, and go hand in hand. Two are right out wrong, and that's one of them. There's a long thread on this in the forum archives somewhere.

Quoting Hotelmode (Reply 5):
I dont know, I currently fly the pax 747-400, one of my friends is now on the freighters (short upper deck) and claims there's a small but discernable difference in aircraft behaviour especially at low speed. I would be interested to see if the trim postion for an identical load distribution is different on the freighters.

The big difference from an aero point of view, as I heard it, was that the longer hump made the aircraft more area-ruled, thus decreasing mach drag significantly.

Cheers,
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bomber996
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RE: How Much Lift Does The Fuselage Provide?

Sun Aug 05, 2007 9:22 pm

The fuselage doesn't always have to be in the shape of an airfoil to generate lift. Wings obviously create a huge low pressure zone over the top of them. This low pressure zone can also extend upwards of the wings several feet. the area of the fuselage directly over the wing is affected greatly by this low pressure zone. It is because of this low pressure zone that most of the fuselage created lift is in-fact helping the aircraft stay airborne.

The is a great model of this somewhere on the internet showing where the high and low pressures are on an aircraft. I just couldn't find it.  drunk 

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F27Friendship
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RE: How Much Lift Does The Fuselage Provide?

Mon Aug 06, 2007 2:13 am

Quoting FredT (Reply 18):
The big difference from an aero point of view, as I heard it, was that the longer hump made the aircraft more area-ruled, thus decreasing mach drag significantly.

The difference in behaviour is noticed in low-speed

Quoting FredT (Reply 18):
discernable difference in aircraft behaviour especially at low speed.

I reckon the 747-400 which has the longer bulb, has less separation, because there is less curvature
 
FredT
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RE: How Much Lift Does The Fuselage Provide?

Mon Aug 06, 2007 3:08 am

Quoting F27Friendship (Reply 20):
The difference in behaviour is noticed in low-speed

Then I'd go with the suggestion made by another poster: Mass distribution effects and/or effects of the other changes to the airframe/controls. Not that it really matters one iota.  Smile

Quoting F27Friendship (Reply 20):
Quoting FredT (Reply 18):
discernable difference in aircraft behaviour especially at low speed.

I reckon the 747-400 which has the longer bulb, has less separation, because there is less curvature

That is not me you were quoting.
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aeroweanie
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RE: How Much Lift Does The Fuselage Provide?

Tue Aug 07, 2007 10:32 am

Bell P-39Q Airacobra:
Wings: 88.5%
Fuselage: 10.1%
Horizontal Tail: .9%
Vertical Tail: .5%

Bell P-63 Kingcobra:
Wings: 100%
Fuselage: 8.5%
Horizontal Tail: -9.1%
Vertical Tail: .6%

Supermarine Spitfire IX:
Wings: 97.6%
Fuselage: 11.9%
Horizontal Tail: -9.5%
Vertical Tail: 0%

Focke-Wulf Fw 190A-8:
Wings: 96.1%
Fuselage: 7.2%
Horizontal Tail: -4.6%
Vertical Tail: 1.3%

Focke-Wulf Fw 190D-9:
Wings: 87.9%
Fuselage: 13.3%
Horizontal Tail: -2.4%
Vertical Tail: 1.2%

Mooney M252:
Wings: 94.8%
Fuselage: 10.0%
Horizontal Tail: -4.8%
Vertical Tail: 0%

Cessna 441:
Wings: 81.4%
Fuselage: 12.2%
Horizontal Tail: -4.7%
Vertical Tail: .2%
Nacelles including overwing portion: 10.9%

Questair Venture:
Wings: 90.7%
Fuselage: 17.5%
Vertical Tail: 0%
Horizontal Tail: -8.2%

Wittman W-10 Tailwind:
Wings: 114.5%
Fuselage: 13.5%
Vertical Tail: 0%
Horizontal Tail: -14.0%
Landing Gear: -1.1%
Strut: -10.9%
Note how everything is fighting on this one

Sabreliner 40:
WIngs: 84.9%
Fuselage: 13.9%
Horizontal Tail: -2.5%
Vertical Tail: 0%
Nacelles and Pylons: 3.7%

Sabreliner 60:
Wings: 87.3%
Fuselage: 14.0%
Horizontal Tail: -3.6%
Vertical Tail: 0%
Nacelles and Pylons: 2.3%

Sabreliner 65:
Wings: 95.8%
Fuselage: 13.7%
Horizontal Tail: -12.0%
Vertical Tail: 0%
Nacelles and Pylons: 2.5%

Sabreliner 75:
Wings: 86.6%
Fuselage: 13.9%
Horizontal Tail: -3.2%
Vertical Tail: 0%
Nacelles and Pylons: 2.7%

Sabreliner 80:
Wings: 85.3%
Fuselage: 13.9%
Horizontal Tail: -2.0%
Vertical Tail: 0%
Nacelles and Pylons: 2.8%

The Sabreliners are all trimmed to the same flight condition. Note how the lift sharing varies model to model.

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