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# Tag Info

0

Your general formulation seems fine. Two things to point out: If you choose to sample only half the wing, then you cannot utilize the relation: $C_L=A_1\pi A$. You would have to do the integration: $C_L=\frac{2}{V_\infty S}\int^{b/2}_{-b/2}{\Gamma(y)dy}$. That being said, maybe you can simplify the expression and get a closed-form result? Haven't tried ...

3

The tail only looks backward when people can usually see it: in the pattern, parked, or flying formation with a photographer in a slower aircraft. Rather than using trim tabs to push control surfaces out of alignment (which adds drag), the entire empennage pivots for pitch trim adjustments. To trim the nose up at low speed, the leading edge of the horizontal ...

0

It sure can; in fact, they are equivalent (with an offset of 1G). In the body frame, the vertical equation of motion is: $$Z+mg\cos\theta\cos\phi=m(\dot{w}+pv-qu)$$ Accelerometers can't measure inertial or gravitational forces, so vertical acceleration as measured is $N_z=Z/m$.

11

"Flies like a brick" is merely a figure of speech. It comes from personal feelings of the pilot when comparing it to an actual plane. It's just like the saying that someone is "dumb as a rock". Obviously, even the most stupid person (or even animal) is much smarter than rock. The saying merely expresses the frustration of the speaker when dealing with a ...

4

Adding to other answers, yes space shuttle is a brick that flying not just a brick. Body-lifting can not be disregarded in hypersonic flight during the reentry, it is not just the wing creating the lift, it is the whole bottom section hitting the atmosphere. Looking at another famous spacecraft, Appollo, it doesn't have any conventional wings but NASA uses ...

-1

The surprise of some engineers about comparing kinetic energy to lift?!?. Yes, let's look at the formulas, and how we apply them. In steady state flight, we talk about the 4 FORCES of flight. F = kg m/s^2 = ma: Lift, Gravity, Thrust, Drag So why not Kinetic Energy KE = kg m^2/s^2 = F × d, or even Power P = kg m^2/s^3 = F × d/t? Because, in describing ...

2

Wouldn't it be better to use no flaps, and rotate at the higher speed that is required? Well, now we are talking about a short field take off. If you ever watched Lindbergh's takeoff the day of the famous journey across the Atlantic non-stop flight, barely clearing a power line on climb out, or even actually done one off a muddy or snowy runway, you know ...

1

Because without flaps extended there is less safety margin for stalling in the landing. Picture above from this answer shows the lift coefficient as function of the angle of attack. With flaps extended, a certain amount of lift is reached at a lower AoA than without flaps. It is a safety feature during landing, when speed needs to be reduced as much as ...

2

Increasing the flaps does increase the drag, but not by that much initially. For the first stages of flaps you gain more by reducing required takeoff speed. If you would increase the flaps more and more, eventually the drag would become too much and you would lose takeoff distance again. Flap setting has an affect on the wing’s lift coefficient and on the ...

5

In the most simple model for subsonic aerodynamics, drag is split into two components: Zero-lift drag, that is all the drag created when the airplane produces no net lift. This kind of drag has again two components: Friction and pressure drag, that is the aerodynamic drag parallel and perpendicular to the local surface. This drag would dominate in a ...

0

No energy is 'lost' to lift. All the energy delivered by the engine is spent, directly or indirectly, in accelerating air downwards in order to produce lift...

37

As everyone has pointed out, it's a joke. Others have answered the lifting-body question (it didn't meet design requirements), so I just wanted to expand some thoughts on the spirit of the "flying brick" nickname. I suspect whoever came up with the term didn't spend a lot of time analyzing it. However, I think it's significant that the nickname is flying ...

3

You want to move a heavy payload at low speeds. This means that induced drag will dominate the aircraft. If we assume a quadratic polar, the least amount of energy for staying airborne is needed when induced drag is three times higher than friction drag. Assuming a quadratic polar, the optimum lift coefficient at that point is $$c_L=\sqrt{3\cdot c_{D0}\cdot\... 0 I don't know if your question relates to the approach phase or the flare. The later as explained above has to do with the elevator, the former i.e for the approach phase you will notice that airliners and even more so fighter jets come on the approach indeed with a high noze up attitude. That has to do with swept wings. Swept wings allow an aircraft to fly ... 21 In addition to its poor glide ratio the shuttles name also stems from the materials its made from as much as it does its poor glide performance. The Space Shuttle's heat shield was made out of LI-900 Silica tiles that strongly resemble bricks and thus the shuttle was sometimes called the "Flying Brickyard". If you would like to know why NASA chose a wing ... 78 The small wings make it fly like a brick. Without the wings it would fly like a stone. Seriously, you are taking the expression too literally. The Space Shuttle is landing like a glider plane with a (not so good) glide ratio of about 4.5:1 (see What was the Space Shuttle's glide ratio?). No brick would be able to achieve that. Designing the Space ... 7 The change in pitch during the landing is called the flare and it is controlled by the pilot (or autopilot for an autoland) using the elevators (i.e. pulling on the yoke). From the Boeing 737 NG FCTM (6.10 Landing): When the threshold passes under the airplane nose and out of sight, shift the visual sighting point to the far end of the runway. Shifting ... 0 For landing an airplane has to slow down. When looking at the lift equation,$$L=\frac{1}{2}c_L(\alpha)\rho v^2A$$We find that, to get constant lift L with lower speed v we need to increase either c_L(\alpha) or wing surface area A (we can't change the air density \rho). Note the explicit dependency of the lift coefficient on the angle of ... 0 Flaps help to increase the lift at low speed, allowing the aircraft to fly at a lower than cruise speed speed. The pitch up is caused by the elevator on the rear wing. 3 When flying at the airspeed that yields the maximum L/D ratio, which is also the airspeed that yields the lowest total drag force, 50% of the total drag is "induced drag", i.e. drag due to the creation of lift. At higher airspeeds, a lower % of the total drag is "induced drag". At lower airspeeds, a higher % of the total drag is "induced drag". -3 About 6% You're looking for the "Lift to Drag" ratio - see here for some examples of different things: https://en.wikipedia.org/wiki/Lift-to-drag_ratio A paraglider is a 10:1 glide ratio. A 747 at cruise is 17:1 - thus - 6% of the power keeps it up, and the rest, 94%, offsets the drag of flying at mach 0.85. 4 The increase in the lift curve slope at low angle of attack is quite normal. At 10° you see the effect of vortex lift kicking in. Yes, that is specific to delta wings. Attached and vortex lift over angle of attack (picture source). This is taken from the excellent Cambridge Core article on vortex lift and these particular diagrams are from E.C. Polhamus: A ... 0 No, at least, not in the way you seem to think. When any aircraft flies, it does so relative to the air, not the ground. So, when you're watching from the ground, the air acts like a treadmill. So, if you've got a 35kt South* wind, and a UAV that's flying North at 25kts, then, from the perspective of the ground, it will be traveling North at 60kts. It will ... 2 A high Cm airfoil does not mean it will be draggy by itself. However, it does mean that when combined with trim devices (e.g. tailplane, elevator, canard, elevon), the overall drag may be higher due to the trim drag component. Since 25% MAC, about which pitching moments are generally cited, generally gives around 20% static margin for low speed aircraft, ... 1 The book's pages won't flap open, but it will bend unpredictably, because its density is so close to that of paper (vs. hardboard) that it must be a paperback. So you can't assume that it's a flat plate. Even if you fling it like a frisbee so centrifugal force holds it flat like LightSail 2, during a 10 km drop, air friction will overcome that and let it ... 2 You have a very thin book. The answer depends on how you initially drop the book. 1. If you drop it flat about its front It will very closely approximate a flat plate; in this case, the pressure drag will overwhelm the skin friction drag. Hoerner, Fluid Dynamic Drag has some empirical data on the drag coefficient of a bluff body (near 2.0): To retrieve ... 0 "Is it dangerous to do a skidding turn to lose altitude without increasing airspeed" This is a great question as it underscores the importance of approaching at around 1.3 times stall speed. Also, of critical importance, is your instructor did NOT request a skidding turn, what was requested was a forward slip, although I admit this may have taken me by ... 5 A "fully-stalled take-off" is an attempted takeoff where the elevator has too much authority. This can cause the aircraft to rotate to an excessive nose up attitude, which can exceed the stall angle of attack, before takeoff speed is attained. Ventral fins were added to some B707s to improve lateral stability, and prevent over-rotation. Over rotation which ... 0 When pondering this question, it is very helpful to consider the Lift vector in proportion to the thrust vector. The average GA plane 4 lbs of lift for every pound of thrust. Depending on speed, it can climb with thrust contributing to vertical lift, not contributing, or even opposing. When a plane is in high cruise speed, it must lower AOA to control ... 9 Quoting the F/A-18A,B,C,D Flight Manual A1-F18AC-NFM-000, I-2-42 2.8.2.8 Control Augmentation System (CAS) [...] The lateral control system uses ailerons, differential trailing edge flaps, differential leading edge flaps, differential stabilator, and rudders to achieve the desired roll characteristics. Scheduled air data roll rate feedback is used ... 3 Bernoulli's equation holds only if there is no energy source in the system. Since the fan adds energy, Bernoulli's does not apply across the fan; in the context of 1-D flow, pressure changes discontinuously across the fan. Due to conservation of mass (no mass source for a simple fan), airspeed cannot change discontinuously across the fan interface. ... 3 I know this was answered a while back but let me give you my two cents. As explained by Peter a combination of the wing swept and low aspect ratio affect the lift production of the wing. But another effect also takes place; vortex lift. aeroalias explains it very nicely on this post: What is vortex lift? In short vortex lift is lift generated by the ... 4 Note that your plots show lift coefficient over angle of attack. This lift coefficient is referenced to a reference area which must be defined somehow. It is customary to use the projection of the clean wing area in the x-y plane for all flap settings in order to keep coefficients comparable. The lift curve slope increases because the real wing area ... 0 Adverse yaw from aileron deflection, at roll initiation, is a function of wing span: a longer wing span creates more adverse yaw. And a long wing span is not what an F-16 possesses. Image source Its main problem at lower airspeed is creating a roll rate at all with such short wings. Deflecting the rudder may help increasing the roll rate - for a left roll, ... 1 First, I would like to point out the question was about limit load on airplane wings, which is different that load limits for the entire aircraft. Therefore, this sounds like an airframe question, not propulsion. Let's look from the wing frame of reference: it does not care if aircraft is going level, up, down, sideways, or upside down. All it cares is ... 0 Please don't run such experiments by yourself! To change the thrust arrangement of an aircraft is to create a partially new aircraft. To do that, you have to know what you're doing and what, exactly, down to numbers, will happen. Adding or spreading engines is not an automatic increase of lift coefficient, so the short answer is, no. 0 It's been done. Thing is, while you may get the theoretical jump to 4.5 Clmax, it's only for the 10 or 15% of the wing that is in the slipstream in the case of the Lazair and it's itty bitty props. So overall, the effect in total CLmax of two extra engines blowing on the wings is negligible. The 4 engine Lazair's performance was almost all from the ... 1 The fundamental way distributed propulsion adds extra lift is by blowing additional air over the wings. This is a direct thrust-to-lift conversion. If you produce less thrust, you produce less lift with this arrangement. So, no, you don't go to a negative AoA to counteract the excess lift produced by running all of your motors at full power. You never ... 0 Nevermind guys, I finally found a proof for this, after a long time of googling: https://www.whoi.edu/fileserver.do?id=218347&pt=10&p=116694 0 The "Bird of Prey" is nothing more than an artist's conception at this point so there is nothing to review from a mechanical design standpoint. Somebody thought it would be neat to make a plane that looked like a bird, but the methods by which birds achieve flight is far different than in modern aircraft. I don't believe there are any practical ... 1 No, there is no reason why aerodynamic center (AC) have to lie on the chord line. As the OP correctly pointed out, Thin Airfoil Theory (TAT) result indicates that the AC: Exists, and Lies on the chord line 1/4c away from the leading edge. However, this is only because the TAT makes the fundamental assumptions that the airfoil is thin, the mean deviation ... 2 Newton's first law of motion states: An object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. The instant you let go of the object, it has 50 kt sideways motion, and 0 kt vertical motion. First, let's assume this happens in a vacuum, so only gravity applies. This is essentially a ... 3 This sort of scenario happens from time to time. Before a flight the crew will calculate the flap setting and speed at which the aircraft rotates based on aircraft weight, the weather conditions, and runway length. If any of these are entered incorrectly, the aircraft could rotate too soon and not lift off when expected. To decrease wear on the engines, ... 6 This answer assumes that the wind is uniform in direction and speed, from the balloon all the way down to the ground. The object will impact the ground directly below the balloon, not "upwind" of the balloon. As the falling object accelerates vertically, the trajectory of the falling object as viewed from the ground reference frame continually becomes more ... 0 Why would the induced velocity at a point P of an infinitesimal section of the filament be zero unless d\vec{l} and \vec{r} are perpendicular ? The cross product in$$ \frac{ d\vec{l} \times \vec{r} }{ \lvert \vec{r} \lvert ^3}  does not change signs when going over the $\frac{\pi}{2}$ angle in between vectors, so the infinitesimal filament ...

11

The first thing I would do is advance thrust to maximum available thrust, make sure both engines are indeed operating. Next I'd check is if the speedbrake is stowed. I would not consider retracting flaps because when you are too slow to climb you are definitely too slow to retract flaps... could be deadly. Normally this kind of situation can't happen ...

3

The FDR would show exactly what the control inputs were so they would know from that. It's important to understand that pitch trim effectively controls the airspeed the airplane will seek naturally without any control input (FAR 25 pitch stability requirements specifically require airplanes to effectively seek a trimmed speed within certain parameters ...

1

Additional response to edited question: object is dropped with an initial groundspeed of zero: the only forces present as object falls are gravity and aerodynamic drag. Drag is a function of airspeed, which has a vertical component as well as a horizontal component. If you use the airmass reference frame, the ONLY significance of wind is that 1) the ...

0

The falling object moves within the mass of air, and suffers no horizontal forces at all... For a ground observer, it drifts with the wind...

2

Transonic buffet, or Mach induced buffet, or high speed buffet, is a flow separation due to the combined presence of shockwave and "high" angle of attack. The boundary layer separation results in random high frequency vibrations. As the AOA increases, the separation and the associated vibrations worsen, up to the point where the crew can no longer read the ...

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