Take an aircraft of your choosing, whether it’s a little Cessna, a business jet, a cargo plane or an airliner. Now, enclose it nearly completely in a fairing with the density of fiber glass or carbon-fiber reinforced polymer. The fairing is optimized for high lift and low drag.
How much would the speed, range, carrying capacity, maneuverability or other important factor be affected?
Wound’t the engines and wings need to be outside the fairing? I’m not sure how this would work.
An airframe basically is a fairing.
The fuselage is a fairing for the interior of the aircraft. The wings, horizontal stabilizer, and vertical stabilizer are fairing-shaped. The intersections of these components hare faired to a greater or lesser degree, and there are ‘speed mods’ available to improve airflow.
Presume the intakes and exhausts are not enclosed in the fairing but the engines are.
As for wings, presume a metal airframe for the wings and then a carbon fiber-type fairing on top of those wings. So, a double layer wing.
So, what would happen if you doubled it?
That’s what I was going to say.
Airplane design is a compromise of many factors, three of which you mentioned (drag, lift, weight). There’s also strength and cost, machinability, probably regulatory issues, and others. Certainly, if we ignore some of those factors, we could improve others. Cost is probably the easiest one on that score: raise the budget and sure, we’ll make it slipperier! But then we’ll also replace the engines with higher performance ones, etc.
Doubled the size of the fuselage? You’d increase drag without increasing lift, unless you made it wing-shaped. The “flying wing” concept has been used, with mixed results. It seems to me that’s the ultimate case of your suggestion.
You also need to account for cooling. If all you had was an intake and a hole for the exhaust, you would quickly overheat. Speaking from a piston-engine perspective, most are air-cooled.
The airfoil is designed for a given envelope of operations. Putting a fairing over it increases its dimensions (and weight) at least, meaning that there would be more drag, meaning that you’d need more power. And if you had a fairing, what’s the purpose of the wing skin you’re covering? Many wings are already bonded instead of riveted, and many riveted wings have flush rivets.
See above. You’d wind up with the same shape, but larger and heavier so you need more power. Remember that a Cessna 150/152 can just lift two FAA-standard adults with full tanks. If you increase its weight, you need to decrease the useful load.
The B-2 flies quite well – with computers keeping it stable. OTOH, there’s the Vought V-173, which is practically all ‘fairing’. There’s a reason they only built one of them.
As the OP asked for a design that optimizes high lift and low drag, it seems that you’d want a high aspect ratio wing that is very thin and long, like those you see in gliders or prop commuters like the Dash 8. Adding a second fairing like the OP proposes would seem to run counter to that design.
I wondered about a design that would optimize high lift and low drag while having two layers of airframes, the inner one made out of metal and the outer one made out of something like carbon fiber.
Most planes are constructed with a rigid frame covered with a lightweight skin. What you’re talking about sounds like adding another skin to that, which would have no purpose.
Humor me, if you will and can.
How are jet engines cooled?
So, you could counter the disadvantages of having an airframe+fairing by having a bigger engine?
What benefit do you expect the second skin to give you that the first skin isn’t already giving you? And what are the requirements of this second skin? Can I just cover the entire plane in a thin coat of paint and call that a fairing?
Presume that the inner airframe is very bad when it comes to aerodynamics but you have to have it.
The requirements of the second skin are: increasing lift, reducing drag, made of something like carbon-fiber or some other polymer.
You’re adding weight but otherwise reducing drag, possibly increasing lift. You might or might not increase range or fuel efficiency depending on how bad the inner airframe is how much more lift and less drag there is, plus how much weight you are adding. You need real numbers to get an answer.
Are you thinking about a flying car or something similar?
Well, the Boeing 787’s wings and fuselage barrels (including the “skin”) are already made out of carbon fiber, but the reason is not due to aerodynamics but due to weight savings.
In aluminim-skinned aircraft, the “skin” of the wings generally do not play a structural role (that is up to the wing spars and ribs), so the skin was already fairly well optimized for low drag. Adding a second CFRP layer to the aluminum skin would do very little to help aerodynamics.
I’ve never piloted a turbine-powered aircraft, so I’ll defer the question to someone who has.
There’s a saying: ‘You can fly a barn door, given enough power.’ When you’re designing an aircraft, you need (as has been stated upthread) to make compromises. You can have a bigger aircraft, but you need a bigger engine to make it fly. A bigger engine means a beefier structure, which requires more power. You need to match the powerplant to the airframe. Now, more power means increased fuel burn. So you have to carry more fuel, which means you can carry less payload. Or you have reduced range. So yeah, you could build a heavier airplane and put on a more powerful engine, but what are you going to give up in exchange?
What Chronos said. What’s the point of having a second skin? Most airplanes are already designed to be as efficient as possible within mission parameters.
A Cessna Skyhawk is design to carry up to four people at a reasonably fast speed for a reasonably long distance for the least amount of power and cost to meet those parameters. A Cessna Skylane will carry more and go farther and faster, but it requires 45% more horsepower and more expensive overhauls to do it. A Lear 35A carries more people, has a greater range, and goes a hell of a lot faster, but they’re more complex than a piston aircraft, requires more expensive maintenance, and burns about 14 times as much fuel as a Skylane. And it requires two pilots.
So first you decide what you want your airplane to do. Then you figure out how you can make it do that as efficiently as possible. As I said at the start, your airframe is your fairing.
Now we’ve got that sorted, what if it was on a treadmill?
MichaelEmouse
Are you a troll or really not know what a fairing is?? Google is your friend. I guess my nerdiness forces me to respond to this… :rolleyes:
Traditionally a fairing is a cover used blend together sharp corners between airplane exterior surfaces. This is a fairing.
ALL aircraft has some type of strong, “ugly” inner frame in some locations to carry concentrated loads. More modern composite planes may use more of an integrated stressed skin structure and be more of a streamlined shape. But it has to have an “ugly” welded steel structure to support the engine.
A Vari Easy is an example. The outer shape is carved from foam and covered with fiberglass to create a streamlined shell, pretty much what you suggest.
Ah yes, the ancestor of the plane that killed John Denver.
I think the OP has some carbon-fiber material that he wants to find a use for.