Pilotasso Posted April 2, 2005 Posted April 2, 2005 This designation is not entirely correct, but itends to stress the absense of the conventional tilt nozzle. The invention was designed and premilinary tests done in Portugal. The only document about it can be found in the official Portuguese aiforce magazine site, in the PDF format here: http://www.emfa.pt/maisalto/Vectorizacao.pdf sadly its all in portuguese but those of you who can scratch a little of spanish will be able to read something. ;) the 2 languages have some similarities. It has been published in 2004 jully's issue of the magazine. I have been aware of it for years, but due to some secrecy of the project I had the duty of not revealing at the request of the authour himself. I didnt know however that it was already disclosed to the public. My brother is from the airforce academy, I came to know of it through him as the tests were being done just a few hundred feet from his bunk. It was never revealded to me the exact method of vectorization, wich left me wondering if this was ever going to turn into a project at all. The inventor is another member of the academy in the engeneering area. Some of my university's teachers were aware of it as well. [color:RED]So how dows it work?[/color] Its realy simple and very engineous, I had my bets but they failed. Putting it briefely what the article says (the first half of it describes its principle showing the Su-37 example) Look at figure 1 as I explain it to you: The engine itself can be of any existing model, the difference consists in the nozzle. Instead of a tilting one it is made by an iris like colar. The collar alows 2 gas flow tipes: The engine exaust jet and a secondary flow of fresh air contoled by external air from another smaller intake wich pressure is controled by means of a variable intake difusor. (the opposite efect when you squeeze a hose tip to increase water speed) The secondary flow may be as much as only 2% of the total flow. So the high speed jet exits the engine into the nozzle colar surrounded by secondary jets of fresh air at lower pressure and oposing speed. When it is inteded to vectorize the jet, one of the secondary flow vanes increases its jet speed, the result is that, in that particular direction there will be a slighly higher shear force between the 2 jets, and at the same time the primary engine jet tends to occupy part of the space previously taken by that secondary jet quadrant. As a consequence the primary jet is deflected into that direction. Are you still with me? :) This aparatus can be adapted into any existing engines, providing that the plane has enough space to accomodate more air admission and the extra hydraulic actuators. The tests were carried out in the portuguese airforce academy using a toy remote plane jet engine purchased in germany! :D we dont have the same resources as the major aviation powers you know. The new Colar nozzle was then grafted in place of the old nozzle. Its section can be round or rectangular as shown in picture 3a. Advantages: -can replace the heavy and expensive to buy, and maintain engine tilt vectorization nozzle. -Less parts required, no exoctic materials needed because the colar nozzle wont be exposed to hot gas all the time. -Much less weight and ease of implementation. Disavantages: -Requires more sofisticated software because the jet defection varies with the 2 jets in the colar (see fugure 6). In some situations the secondary jet flow may be disrupted and the main jet creates a vortex inside the colar causing loss of vectorization and engine thrust. (usualy happens after the non linear evolution in that graphic) -It may be that the deflection angle of the jet engine could be slighly reduced in comparison to the convention tilting nozzles. But tests are still undergoing to fix these disavantages. The inventor has gone or will be going to the US to complete the studies with the support of one of the US aviation companies for a possible future aplication in its airceaft. What company that is, its being kept in secret, this information is not in the article but I do know that it is hapening. In the end the US will probably take the credit for the invention, as almost all great Portuguese inventions are. So when you see these jets in action you wont be duped that it was "another great US achievment", you will know where it came from while no one else supects you know that. P.S. No, no this aint aprils fools. (i waited till today april 2nd to publish this) .
SwingKid Posted April 2, 2005 Posted April 2, 2005 So the high speed jet exits the engine into the nozzle colar surrounded by secondary jets of fresh air lower pressure and speed. When it is inteded to vectorize the jet, one of the secondary flow vanes decreases its jet speed, the result is that, in that particular direction there will be a slighly higher shear force between the 2 jets, and at the same time the primary engine jet tends to occupy part of the space previously taken by that secondary jet quadrant. As a consequence the primary jet is deflected into that direction. Interesting... Why does Fig. 1 show the secondary flow moving in the opposite direction to the primary flow? Would this not reduce the total thrust? -SK
Skywall23 Posted April 2, 2005 Posted April 2, 2005 Who would tell heh Pilotasso? I must confess that Im surprised. :) Never thought that my country would be able to do this, but still...:)
Pilotasso Posted April 2, 2005 Author Posted April 2, 2005 Interesting... Why does Fig. 1 show the secondary flow moving in the opposite direction to the primary flow? Would this not reduce the total thrust? -SK I have corrected the post above, the aparatus does work with oposing jets, I have missed the schematic as I read in a hurry. The oposing jets reprsesent only 2-6% of the total and contact between the 2 is reduced when comparing with the total volume, although drag is made there, it is only in the boundary of the 2. But the effect that creates the deflection is the difference of pressure to one of the sides, not the friction itself. Loss of thrust is not mentioned, but I guess as explained above it would hapen to a small degree. The process inside the colar has to be controled by computer in order to avoid stall vortexes between the 2 jets, I guess then we can say there will be a loss of thrust for sure, but its only a case of acidental loss of flow control. .
D-Scythe Posted April 2, 2005 Posted April 2, 2005 Have you seen the TVC system on the PAC-3? Although it's the sketchy, apparently the hittile interceptor is not only controlled by aerodynamic fins, but also small rocket motors (3?) built into the missile forebody that help to increase terminal agility. On top of that, it has an active radar seeker for more reliable end game performance. Only problem is that it seems to target (and destroy) both friendly and enemy aircraft... :D
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