Here is a web site that describes AOA complete with animation. http://wright.nasa.gov/airplane/incline.html There is another site that describes pitch. Just change the incline to pitch.Tom

Are there any 737-700 A&Ps out there? I would like to know what sensors supply AOA data to the ADIRU ? Thank's from Jim

i'm not a pilot or anything but this is what i make of it?AOA = not body attitudeAOA is the angle at which the AIRFLOW hits the fusethe body attitude is relative to the horizon, the AOA is relative to the airflow, air can flow in many ways and not always parralell tot he 'flat ground'But you're right in saying the EADI pitch indication shows the body attitude.

perhaps 1,0 is the defaulted figure when the AoA measurement is not operational?(e.g. no airflow = no angle of attack)not sure though

Jim ,I can tell you there are 2 AOA sensors on the fwd sides of the fuselage ,one on the left and one on the right just below the pitot probes(they look like small wings that rotate in a resolver). They send a 28VAC signal to the Adiru L and Adiru R independently.

Just as a matter of interest Randy, in your diagram what do (4) and (5) designate? I have no idea what the arc next to (4) is. I assume (5) is 0.0 degrees but I'd be interested to know what else your manual has to say about it.I've only just noticed the following statement:'The angle of attack indications display ADIRU aircraft body angle of attack.'This would be different to 'true' angle of attack which is, I believe, measured relative to the mean chord line. This would explain why in level unaccelerated flight the pitch angle matches the displayed AoA, even though I would expect the 'true' AoA to have some other value.The definition of mean chord line is probably somewhat arbitrary on a wing that is twisted unless they go to the trouble of using calculus to find it, so it seems simpler to display aircraft body angle of attack rather than 'true' angle of attack and save everyone a lot of hassle, particularly as the position of the mean chord line is also affected by flap/slat position...

Here you gohttp://forums.avsim.net/user_files/39224.jpg[h4]Best Wishes,Randy J. Smithhttp://img.villagephotos.com/p/2003-8/196432/winglets_lg.jpg [h3] AMD XP 2200 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF2 MX 32 MEG and still runs GOOD!|WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"[/h3]

"I would like to know what sensors supply AOA data to the ADIRU ?"The AOA sensors, of course, Jim ;-)The AOA sensors are freely rotating vanes on the side of the fuselage. Here's a pic of one nestled inbetween the pitot-static probes below the cockpit of a 737 (although I can't recall what type of 737 it was).http://members.ozemail.com.au/~b744er/PitotStatic.jpg Cheers.Ian.

Ian, what's a pitot-static tube? I thought they were just pitot tubes. Aren't the static ports further back and flush?;-)Lee Hetherington (KBED)

Not on a 737. the 737 uses pitot statics, and Ian has indicated in the pictures where the static ports are. Some airplanes (like the 757) use separate pitot tubes and flush static ports, while others (like the 737) use combined pitot-statics.Don S.

Actually, there may be variations to this Don. The 737-600~900 notes I have with me at the moment do show separate pitots (3) and (flush) statics (6!). I haven't had a look at our airline's recently, however.Lee... The combined ones look like the static ports are simply holes in the pitot tube, but they aren't. Each static port(hole) has it's own mini-tubing system so that the pressures are not mixed. I don't know what the advantages are, other than compactness.Unlike older gen aircraft, the newer NG pitots don't feed the Air Data Computers (or rather ADIRUs) directly. The air pressure is converted into an electrical signal close to the probe itself and this electrical signal is then sent to the ADIRU's. This helps reduce data processing delay errors. Even so, the NG also has a predictive airspeed function built into the displays. When the aircraft is accelerating or decelerating, the system tries to predict a trend in airspeed and then adds/subtracts a few knots to the cockpit displays when appropriate.Hope this helps. Cheers.Ian.P.S. There are also pitots up on the tailfin for the Elevator Feel System (you can see their outline in Spot view).

Craig,Correct observation. Here is why :At CRZ the amount of lift produced is equal to the weight of the aircraft (assuming a very small angle of fixed wing incidence) hence(1) Lift = Weight = 0.5 * rho * WingArea * TAS^2 * Cl (2) TAS = SQRT(rho_o / rho) * IAS + b(M)(3) Cl ~= (dCl/dAA + a(M) ) * AoA [Lift coefficient](a) b(M) is a Mach correction factor usually of the order of 4-6 knots hence pretty small for the present purposes. rho_o is the air density at sea level.(:( a(M) is also a Mach correction factor. Furthermore, for small angles of attack (dCl/dAoA) is ssentially constant and a(M) is very small for the present purposes (i.e. Cl is a linear function of AoA)In view of the above remarks, substituting (2) and (3) into (1) you obtain :Weight = [0.5 * rho_o * WingArea * dCl/dAoA ] * IAS^2 * AoAIn the relation above the term is square brackets is constant, hence for fixed weight and fixed IAS, you have the same AoA !Small differences will be observed mainly as a result of Mach correction factors. These are indeed modelled in our NG using compressible formulae (Prandtl-Glauert beta factors for those familiar with aerodynamics).Hope this clarifies the issue.Regards,VangelisPS_1. In SU2 lift characetristics are fixed for FS9 (MSFS argh!) so that pitch figures in all stages of flight match those of the good book. Stall characteristics for both FS2K2 and FS9 versions are also carefully adjusted following tests in 3D motion sim (actually motion has been turned off else the thing would disintegrate from ensuing buffeting).PS_2 As already noted above pitch and AoA are two different things. You can stall an airplane pitch down ! Try 150 IAS and descend at 5000ft/min--- check your AoA and at 10 deg AoA floor the throttle.============================================== E. M. Vaos Precision Manuals Development Group www.precisionmanuals.com==============================================

VangelisVery interesting post - I like to see a few equations, which I think do help to clarify things. Appreciate you taking the time to present this information.

Perfect....now i can bring this baby on board a carrier!. How about a launch bar on the nose wheel so I can hook up to the cat and a tail hook too!Remember to catch the three wire.Tony

Hi Craig,another useful equation is the following:Flight path vector angle (fpv) = Pitch angle + AoA also denotedgamma = theta + alphaThis will give that AoA and Pitch Angle are equal at cruise, where fpv is zero.Hope this will shed some light over the recent discussion on pitch angles and AoA :-wave/SAS108, Owe Wiktorsson Msc Aero