[Pyrotex]

Originally Posted by arkain101

LOL...if one was to build such a plane where the engines were located in such a position that they provided substantial thrust of air over the fusilage even while the plane/flying machine was at rest relative to the ground, would it, could it fly, and even maybe hover?....

The answer is "yes" or "damn near yes".
In the late 70's, Mississippi State University worked with the DOD on a new kind of plane. I cannot remember its name so I couldn't Google for it. I will try to describe it.

Ordinary fusilage, ordinary wings sticking straight out (perpendicular) from fusilage. However, about 5 feet out from the fusilage, the wing bends straight down and is shaped like a semi-circle, open side up. At the other end of the semi-circle, the wing continues straight out (horizontal) as if nothing had happened. In the geometric center of the semi-circle, an engine is mounted, with a propeller that just barely fits inside the semi-circular section of wing.

A propellor with a circular cage around it is a "vented propellor" and has a high propulsion efficiency. Well, the configuration above would be called a "semi-vented propellor". Plus, the cross-section of the half-cage itself is the cross-section of a wing. Therefore, the propellor pulls a LOT of air over that semi-circular shaped piece of wing and creates a LOT of lift.

No, it didn't hover. But it allowed the plane to fly at really, REALLY slow speeds. Looked funny as hell, though.

[GAHD]

Artificially increasing is indeed a very intersting thing to consider in aeronautics. Traditional prop-planes have increased lift in the areas directly behind their engines because the prop forces more air over and under the wing, increasing the velocities involved and thus incresing the lift generated by that area. Modern jet-aircraft have lost that extra lift thatnks to under-wing or in-fuselage design.

[GAHD]

Just a side-note, the Bernoulli principle is a very important part of flight. Bernoulli's equation is for the more math-oriented.

[arkain101]

The easiest way to see the Bernoulli Principle in action is through a discovery I made.

Turn on a water tap to a fast stream flow. Take a Spoon from your kitchen that is a good size. Hold it in hand by finger and thumb, letting it dangle vertical, scoop part at the bottom. While holding the spoon vertical and allowing it to move loosly like a pendulum, place the back side of the scoop towards the stream and Voila, Flight has been discovered.

The bend in the spoon makes the stream of water accelerate as it passes over the curve. It creates a low pressure area and the atomosphere wants to get 'in that low pressure area'. So the water then glues itself to the spoon and the mass of it swinging AROUND the curve of the spoon and shooting in the opposite direction the lift on the spoon is being directed causes the bernoulli principle.
Lift is created by the cintrifugal forces of the air that has angular momentum around the wing and is literaly attatched to the wing surface.

Just as if you were to swing on a roap that I was holding onto, It would pull me around. This if lift effect.


My hovering plane design is to create a flexible chassy that is wrapped in a tight smooth flexible fabric. The plane Only needs to push up on the fabric with the internal framings to create a dynamic adjustable ration wing effect. On the sides, top and bottom of the plane design.
Engines that are mounted around the plane (which is invisioned as a saucer like shape). Blow air right at the plane through thin vents that expand widely to sort of wrap half way around the 'edge' of the saucer, the part that cuts the wind. The vent is wide but blows a thin layer of highly accelerated air. Both front and back. The engines would probably need to ahve the ability to reverse air flow direction.

The design is just a napkin sketch. The aerodynamics could get quite interesting, if one was to aim the air stream from two engines towards eachother to cause the two interacting high velocity air to generate an efficient lift.

[GAHD]

It's scary how similar our basic ideas ar arkain, and my design started as a napkin sketch too. Great minds...or simple ones

My design keeps fuselage and wings, but ducts the engines backwards through the wings to create the increased lift. It also incorporates a flexible chassy, I was considering neoprine as the skin but sch a design would preclude the use of a standard jet engine as the exaust would burn away the skin surrounding the exit ports. Perhapse secondary turbine could draw force from a main engine situated in a heat-sheilded area ("fire paste" has intrigued me for use in such an exaust situation before) but that's just more weight and would probably offset the generated lift too much. More likely I'll just use a few ducted electric ans at different angles of attack as the power plat for the 4'-6' test model I want to build.

[arkain101]

Yes, it is lol.

In fact I spent a moment last night thinking about it, and realised i could just use a typical wing. On this wing place a few engines located out in front of the wings edge of attack by a bit of distance. The Engine itself would be a vented intake, that can lift up and down to act a bit like a flap. The engines would be encased in a vent like body which takes that efficient setup and blows high pressure air into the main chamber of the duct. The exit ports would be located along the wing edge and blow a fast layer of air over the wing making its own wind. It would of course try to propell itself forward But with a specific bend in the wing and a flap to catch and direct the high speed air from the tail edge of the wing back towards the ground it should lift.

I get confused if it would lift or not. I mean can we really defy gravity by hanging onto a vacuum? If I was to hold onto a wing and blow air out of my mouth fast enough could I make myself fly?
I guess according to my mass transfer description of how lift works I suppose it would work. As you are creating upwards directed momentum.

[CraigD]

All of the folk interested in STOL/VTOL might find the history of aircraft designed to exploit the Coandă effect interesting. Thought nowhere as successful as vectored thrust systems such as the Harrier’s, or tilt rotors like the Osprey’s (thought some would argue that “successful” is an exaggeration of the Osprey’s, or even the Harrier’s service records), a number of both weird and unremarkable –looking aircraft fal into this category.

Improvements in takeoff performance in prop aircraft due to a combination of tractor (propeller in front) configuration and enlarged trailing edge wing flaps near the propeller are common in STOL aircraft – there are, to my knowledge, no widely used pusher (propeller in back) STOL airplanes, even though this configuration has proven to have improved in-flight efficiency, and is very popular in “exotic” high-performance aircraft like the VariEze and the Beech Starship.

I really wish I could find a reference to a very strange looking, 50s-era experimental aircraft that paired a large-diameter prop with incredibly big wing flaps in an attempt at near VTOL performance, - arkain’s description sounds much like it - but I’ve tried and failed to in a reasonable amount of searching.

[arkain101]

Quote from wikipedia.
Coandă effect

Demonstration
If one holds the back of a spoon in the edge of a stream of water running freely out of a tap (faucet), the stream of water will deflect from the vertical in order to run over the back of the spoon. This is the Coandă effect in action.

This demonstration is the combination of the Venturi effect and the Coandă effect. The Venturi effect would cause a drop in pressure between the spoon and the stream of water, which would then be drawn towards the spoon. Once the surface of the stream hits the spoon, the Coandă effect keeps it running over the convex surface.

I had a chuckle when I read this. Due to the fact that I had in my own doing discovered this effect and anaylised its phsyics and found an application for it.
So there is the bernoulli principle
and
Coandă effect

I find there are some differences between the two.

Anyone want to cleary point them out to save some time?

[arkain101]

Quote from wiki on coanda effect.
Lift from an airfoil

Some people have attempted to explain how a wing generates lift, by invoking the Coandă effect. However, this theory does not produce quantifiable data, and so it is unable to predict such things as the thickness of the boundary layer. Professional aerodynamicists regard this theory as a fallacy. For example, the theory states that air “sticks” to the surface because of its viscosity. This implies that if the viscosity of the fluid changes, the amount of lift an airfoil produces should change in proportion. Experiments show that the amount of lift produced by a real wing is independent of viscosity over a wide range. The real Coandă effect requires turbulence, so it occurs only if the viscosity is sufficiently low. Furthermore, the air speeds up above a wing's upper surface. The theory assumes that the relative air-flow meets the wing at the same velocity as in free air and then follows the curve. This understates the pressure gradients by an order of magnitude.

This is why I created a topic here that better and seemed to re-explain lift. The topic went somewhat overlooked.
-its here, http://hypography.com/forums/physics...highlight=lift

I said and stand by, lift is created from the angular momentum of the mass of the air swinging around the curve of the wing. The air is glued to the wings surface from a low pressure enviroment in the atomosphere above the wings sufact. The air wants to get thrown away, but the vacuum is keeping it attatched, and the air is forced to trade places with the wing, the air gets pulled down by the wing, and the wing gets pulled up. The greater the vacuum and exhange of mass the greater the lifting effect.

This is flight explained. And using this data, a wing could be very much differently designed. It could have a smooth thing knife edge front, that slowly curves upwards and then more dramatically curves downards below the height of the wings front. The bottom of the wing shape would remain flat, and grooved or such to create a less drag enviorment, then slightly just curve downwards to meet with the top of the wing, like a fixed flap, although just enough to match the velocity, power, lift, and drag specs regarded to fusilages needs.

The same as a rocket going into space by exchanging mass from exhaust and the rocket body. The mass of the fuel/exhaust gasses being accelerated out of the rocket causes a trade in momentum where the rocket goes up and the fuel goes down, or in other words, opposite directions.

In the same manner a wing grabs air or a fluid and throws it downwards like the rocket (without creating much drag). The exhange in mass and momentum causes the wing do get thrown up relative to how much mass of the air is thrown down.

[Qfwfq]

An early example of aerodynamic lubrication is the golf ball. Surprisingly, it shows that the overall drag can, in certain cases, be less with turbulent flow than with laminar.

I also have a vague memory, from some 30 or so years ago, of a missile design emloying a small, flat circular plate to create a shock wave all around the craft. I imagine it reduced drag but ran into various engineering troubles.