why is a rectangular intake needed instead of a conical one for substained supersonic flight?Concorde intake?
597521
The Concorde intakes are made highly adaptable to varying flight conditions through a set of movable vanes that are positioned for optimum performance. I would guess the rectangular design simplifies the vanes, which would have to be irised-concentric or clamshell based if used in a conical inlet. According to the ref., at supersonic speed the intake slows the air, whose relative velocity is supersonic, to subsonic speed to prevent instability. At supersonic cruise, the intake is said to contribute 63% of the total power. (This probably refers to the air flow it contributes to the total flow.)
45989
I not very sure about applications of air resistance force. However here is a possible answer. \n\n  There is always some force that provides centripedal acceleration. Air resistance for the straight plane is perpendicular to surface of plane = D (say)\nLet radius of circular motion be r and tangential velocity be v\nSince this force is given to be constant at that altitude,\n\n     Dsin10 = mv*v/r   .........(1)\n     Dcos10 = mg       .........(2)\n\nSolving, we get,\n      tan10 = (v*v)/rg\n\n         r  = (v*v)/gtan10\n         r  =  (135*135)/(9.8*0.176)\n         r  = 10566.44 m\n\n By simple trigonometry, you can draw a right angled triangle ABC representing the plane as hypotenuse AC where B=90 degree, C=10 degree, BC=r and AB = elevation = H\nHence, tan10 = H/r\n           H = tan10 * r\n             = 0.176 * 10566.4\n             = 1859.69 m\n\nIf one of the planes wings which was down comes up after one rev, then the approx. change in altitude will be 1859.69m
904693
If you've got a submarine shaped like a flat-nosed bullet and accelerate it to supercavitation speed, a few hundred km/hour, the water in front of it will be pushed sideways and the sub will be surrounded by a bubble containing nothing but a little water vapour at low pressure.   The only part of the sub in contact with the water would be the flat nose tip.  If you could make it work, you'd cross the Atlantic at airliner speed.  Problems that spring to mind are the huge amount of energy you'd need, how you'd see far enough ahead to avoid an obstacle like a whale, and the effect on marine life.  A possible fuel would be aluminium powder, which you'd react with the water.
483369
Runway 21 would be into the wind, but you're going to be applying right rudder to counter the left yaw disturbance due to the left engine out, and will be sideslipping to the left. To keep you on course you need the headwind to be at least partially a crosswind from the left, so given the choices, that would be runway 30.\nAnother reason to have the crosswind from the left: If you are going to use reverse thrust to decelerate, "Given a choice, it is advantageous to put the cross wind on the same side as the failed engine." (ref.)
31492
the answer to your question is pretty simple in logic.\nthe factor K for venturimeter is higher since the friction due to obstruction to the flow is higher in the case orificemeter. where as in the case of venturimeter the friction due to the difference in flow area is compensated by graduated tapering.
832693
l'angle de 35° par rapport à celui de 45 favorise un meilleur plané du javelot par une pente plus douce. d'autre part au niveau anatomique  ou plutôt biomécanique un lancer à 45° efficace nécessiterait trop de contrainte en terme de position et par conséquent ne permettrait pas une bonne production de la force musculaire
527581
Expansion coefficients for air can be determined using the attached link.\n\nBest wishes !
262603
it all comes down to the difference between laminar flow and turbulent flow.  think about a non-spinning ball moving through the air:\n\nif the surface of the ball is perfectly smooth, then the motion of the air just near the surface (this is called the boundary layer) will be perfectly smooth too.  as the air moves around the sides towards the back of the ball, the angle between the direction of the air's motion and the surface of the ball will get bigger and bigger.  \n\nat some point the boundary layer won't be able to "stick" to the surface anymore and will detach.  (this phenomenon is called boundary layer separation.)  the faster the air is flowing, the separation point will be closer to the place at which the ball is widest.  this separation means that, behind the separation point, the air near the ball's surface will be turbulent.  it is essentially what happens to an airplane's wing during a stall.  \n\nbecause the ball is symmetric, the turbulent area will be equally spread between the left and right sides of the ball.\n\n(a brief aside: laminar flow exerts a greater pressure on the ball's surface than turbulent flow does.  this is why aircraft engineers go to great lengths to make the wings of a plane very smooth - if the airflow around the wing is very smooth too, then the wing can generate greater lift.)\n\nanyway, so everything's symmetric for a ball that's not spinning.  now think about a ball that's spinning around it's vertical axis.  the relative velocity of the air to the ball's surface is different on the left and right side because of the spinning.  this velocity difference means that the boundary layer separation happens at a different place on the left or right side.  \n\nthis means that the left/right side of the ball will have a larger/smaller area with turbulent flow at the surface.  the symmetry is broken and the resulting pressure difference causes a net left/right force on the ball, which makes it curve.\n\nthere is a nice picture of the non-spinning ball at the bottom of this page:\nhttp://astron.berkeley.edu/~jrg/ay202/node97.html\n\nhere's a paper about it, with a nice picture that shows the laminar and turbulent asymmetry:\nhttp://www.wooster.edu/physics/JrIS/Files/nowicki.pdf\n\nmore pictures near the bottom of this page:\nhttp://www.aerospaceweb.org/question/aerodynamics/q0215.shtml\n\ncheers!
712219
The Preissmann slot model is using a fictitious slot above the adit so as to use the open channel flow to simulate a pipe flow.The simulation is good as long as the pipe flow is for a full pipe and the pressure is not sub atmospheric.\nTo help you in modeling try AFT Arrow software.
14321
First, look at any typical airfoil shape. It is sort of teardrop shaped, with a round end and a pointy end, but not symmetrical--one side seems flatter than the other. Let's imagine that the pointy end points to the right, the round end point to the left, the flatter side is on the bottom and the rounder side is on top.\n\nLet air flow from the left to the right. Air flowing near the airfoil at speeds that are not too fast (less than the speed of sound) is not compressible. Let's follow two tiny blobs of air that start next to each other, but approach the round end of the airfoil in such a way that one blob goes up and over the airfoil, while the other slides over the bottom. These two blobs will arrive at the pointy end at approximately the same time. But, the one going up and over as a longer path to take and therefore must travel faster. All the air molecules in a blob are actually thrashing about randomly and can collide with other air blobs nearby as well as the upper surface of the airfoil. This is true of the upper blob and the lower blob. But, if the upper blobs average speed is faster, then its molecules collide with the upper surface of the airfoil less over the trip from round end to point end than do the molecules in the lower blob. Therefore the pressure caused by the collisions of the molecules in the upper air blob on the upper side of the airfoil is less than the pressure on the lower surface caused by collisions of the lower blob's molecules with the lower surface. This means there is a difference of pressure between the two surfaces--pressure drops as you go from upper to lower surface. If the airfoil is rigid, then this difference in pressure will become a force exerted on the airfoil from below, called lift. This lift is what makes an airplane rise on takeoff as it rushes through the air with its wings whose cross-sections are airfoil shaped, rounded end into the oncoming air and flatter side towards the ground.
491132
drag and thrust are not equal, thrust outpowers drag
742139
An energy-efficient, carbon-composite, centrifugal fan designed to direct a high flow rate of air from above to the radially outward direction driven by an electric motor.\n\nWhy do you ask?  Do you have any good referrals?
962609
The M/A of a wedge (disregarding friction) = cot(wedge angle)\n\nUnfortunately, there's a LOT of friction, so it's not so simple after all!
335287
A supercharger mechanically increases the amount of air going into the intake prior to entering the combustion chambers. This is also the same purpose of a turbocharger. Where a SUPERcharger is generally BELT driven, a TURBOcharger derives its power from a "fin or fins" propelled by exhaust air.\n\nAs for your second question, my money is on the cobra.
762462
Do you mean the FEA program if so the most important factor and the one that i used to always get wrong is node number and separation. Try a simple shape with fixed point load and pivot. First try with 10000's of nodes then try with 100's then with just 2 or 3 dependent on shape the difference to the results are big. Node choice comes with experience which i am lacking!!
1146635
Its mostly because of aerodynamics.With the Present propulsion method we cannot device those aircraft.Primarily circular aircraft shud rely on air for lift and it cannot take off as easy as normal one used now.\nMoreover Manoeverability cannot be achieved to the max with present technologies.\nBut who know it might be real one day..we cud have them.
517769
In the US, see the FAA web site, FAR part 103. The aircraft must not be capable of more than 55 knots calibrated airspeed at full power in level flight.\n\nDo you know there is a special category for aircraft questions?