AOA, Can someone explain this to me?

[Gatordev]

Awesome...

Gator, you gotta agree you opened up for that comeback

I guess. I really don't see the dig (although I understand that it was there). It's like saying elementry school kids suck because they can't do alegebra. Well, duh, they're not meant to do it yet.

 

[Pitchlock]

Since I have no idea what the current training syllabus is like this book may be redundant, but I do remeber not learning about it until I got to the fleet:

"Aerodynamics for the Naval Aviator"
http://www.amazon.com/Aerodynamics-Naval-Aviators-reprint-676-T/dp/156027140X

Makes a great stocking stuffer. At one time it was an official navy publication and you could order it through the squadron.

Another book I like that is very basic (calculus not required) but good on the concepts is:

"The Illustrated Guide to Aerodynamics" by H.C. "Skip" Smith

It also important to know that any number published in Natops is arrived at from experimental data as well as theoretical. The theoretical numbers aren't calculated for every possible flight condition nor does the initial flight testing test every condition. This is why with experience sometimes you can do 'better' than the published numbers. Or lead yourself to believe you are smater than the engineers.

 

[wiseguy04]

FWIW, the last time someone tried gouge numbers for a T-45 divert, I believe the result was a flameout followed shortly thereafter by a FNAEB. Your mileage may vary, consult the Dash-1.

Ahh yes, the farmer's field incident. Actually the reason for that flameout was because the student was using the dirty bingo chart instead of the clean bingo chart, not that it would have made that big of a difference. (who knows)

 

[NavyLonghorn]

Ahh yes, the farmer's field incident. Actually the reason for that flameout was because the student was using the dirty bingo chart instead of the clean bingo chart, not that it would have made that big of a difference. (who knows)

Wouldnt dirty bingo be a higher number? More power needed with all that drag hangin out.

 

[scoober78]

Ahh yes, the farmer's field incident. Actually the reason for that flameout was because the student was using the dirty bingo chart instead of the clean bingo chart, not that it would have made that big of a difference. (who knows)

I think he means Bingo range...? That would indeed be a lower number for the reason you suggest.

 

[larbear]

Ahh yes, the farmer's field incident. Actually the reason for that flameout was because the student was using the dirty bingo chart instead of the clean bingo chart, not that it would have made that big of a difference. (who knows)

Yeah, after flying a "modified bingo" for a bit, they settled on dirty bingo numbers, which are flown much slower than a clean bingo.

 

[Intruder Driver]

Back to the original scenario: On a low level and not sure if you can make it back to the field. Real simple (I'm assuming you're talking jets):
(1) You don't stay low (low altitude = max fuel burn); immediately fly the bingo profile.
(2) There is no modified bingo profile. Fly the bingo profile by the numbers. Navy pilots have, decade over decade, been proven wrong when they thought they had a better plan than the bingo profile. Accident boards point it out early in the proceedings.
(3) 95+ per cent of the fuel burn is on the climb, so don't panic when you get to the appropriate altitude and you have no gas. You'll be fine.
(4) Use the time in the descent, at idle, to get your story straight, especially if there is more than one person onboard.
(5) Ask for the arresting gear. If by chance you flame out on rollout, the RAT won't work and you'll lose electrical power. No harm, no foul in taking the gear.

 

[Intruder Driver]

Regarding AOA: AOA is only accurate if the aircraft is in balanced flight. When the power is way back on a descent, it's easy to have one engine throwing out a few more velocities than the other one, so trim the ball.

 

[Purdue]

Back to the original scenario: On a low level and not sure if you can make it back to the field. Real simple (I'm assuming you're talking jets):

Regarding AOA: AOA is only accurate if the aircraft is in balanced flight. When the power is way back on a descent, it's easy to have one engine throwing out a few more velocities than the other one, so trim the ball.

I'm specifically talking about my single engine prop-driven T-6A Texan II.

And in the case in question, I'm talking about a scenario where I've lost the engine completely and am trying to stretch it out and make it to a runway. The AF says t oignore my AOA gauge and just always fly 125 for best range no matter what the AOA indicates (then why have a little triangle labeled Max Range?)

Also, I jumped in a sim the other day, and decided I was going to test my theory. I killed my engine at VFR entry (maybe 10 miles from the underrun to my runway?). Zooming from my entry airspeed of 200 knots to he AF instructed clean glide speed of 125 knots I crashed before I made it. Gliding at max range on my AOA I touched down with about 8 feet of pavement behind me on the underrun.

I picked this because they tell us that it's impossible to recover the aircraft from VFR entry. It's generally assumed you cannot possibly make it to a landing surface until you are at LEAST on "45 to initial". And they're right... it is impossible if you don't fly max-range AOA.

Of course, as someone stated earlier... I'll play the Air Forces game.... and to keep myself safe, were I to encounter a real emergency, I'd fly as instructed... even if it wont get me where I need to go.

(** for the sake of accuracy, I dealt with a "snapshot" of myself in the sim so I started from the same exact position after my failed engine, Zoom, Turn, Climb, Clean for both glides.)

 

[Intruder Driver]

I've learned in 6,000+ hours of flight time, most of it low level, and also from some salty dogs in the Caribbean flying DC-3's, Cherokee 6's and other assorted cats and dogs, that the key to surviving the loss of an engine at low altitude (unless you have a gazillion knots on), is to make no turns (or minimal turns). Convert airspeed to altitude, and cherish your liftees, which are ruined by turns. Obviously turn to make a runway, within reason.

During my 2.5 years as Air Ops in Roosy Roads, three civilian airplanes crashed in Puerto Rico because they tried to turn back to the field too early after losing an engine after takeoff or lost an engine enroute (<1000') and ran out of lift from making turns looking for a place to put down. In all three cases, it was determined that, had they simply maintained straight and level flight, they could have likely gotten a restart or flown safely into a controlled (crash) landing. As it was, all three crews died.

 

[Gatordev]

I've learned in 6,000+ hours of flight time, most of it low level, and also from some salty dogs in the Caribbean flying DC-3's, Cherokee 6's and other assorted cats and dogs, that the key to surviving the loss of an engine at low altitude (unless you have a gazillion knots on), is to make no turns (or minimal turns). Convert airspeed to altitude, and cherish your liftees, which are ruined by turns. Obviously turn to make a runway, within reason.

Please don't take this as arguing your point, as I think it's very valid, but here's some food for thought for those that care... There is that happy place where you can get enough turn in to make it worth while and minimize the increased descent rate. For example, a power loss for the T-34 on, say, the crosswind, isn't the end of the world. Apparently 45 degrees is the magic number. More than that, and you lose the benefit. Of course, you have to be starting out high enough, which just proves your point, Intruder.

Disclaimer: My post isn't meant as an excuse to go against FTI/SOP for you studs. I know some squadrons have a "forward of the wing" policy in effect.

 

[A4sForever]

....Convert airspeed to altitude, and cherish your liftees, which are ruined by turns. Obviously turn to make a runway, within reason.........In all three cases, it was determined that, had they simply maintained straight and level flight, they could have likely gotten a restart or flown safely into a controlled (crash) landing. ...

Not sure what you mean by a "controlled (crash) landing" ... sounds like a crash by any other name to me .... but basically your premise is O.K. ... go straight out, no turns on an engine out (...done it, military & civilian w/ engine loss on T/O) ... but in many cases you HAVE to make turns after take-off (HKG, ANC, SFO come to mind immediately. The immediate turn requirement is usually factored into your runway takeoff performance on the civie side.

It seems the civilian world pays more attention to that than my military experiences would indicate --- perhaps because the civilians have come up with more & weirder places to put aerodromes where vertical obstructions abound ... ???

 

[llnick2001]

I'm specifically talking about my single engine prop-driven T-6A Texan II.

And in the case in question, I'm talking about a scenario where I've lost the engine completely and am trying to stretch it out and make it to a runway. The AF says t oignore my AOA gauge and just always fly 125 for best range no matter what the AOA indicates (then why have a little triangle labeled Max Range?)

Also, I jumped in a sim the other day, and decided I was going to test my theory. I killed my engine at VFR entry (maybe 10 miles from the underrun to my runway?). Zooming from my entry airspeed of 200 knots to he AF instructed clean glide speed of 125 knots I crashed before I made it. Gliding at max range on my AOA I touched down with about 8 feet of pavement behind me on the underrun.

I picked this because they tell us that it's impossible to recover the aircraft from VFR entry. It's generally assumed you cannot possibly make it to a landing surface until you are at LEAST on "45 to initial". And they're right... it is impossible if you don't fly max-range AOA.

Of course, as someone stated earlier... I'll play the Air Forces game.... and to keep myself safe, were I to encounter a real emergency, I'd fly as instructed... even if it wont get me where I need to go.

(** for the sake of accuracy, I dealt with a "snapshot" of myself in the sim so I started from the same exact position after my failed engine, Zoom, Turn, Climb, Clean for both glides.)

That's great you took the time to do that. I'd mention it to the instructor (if you're pretty comfortable with him). Use your judgment though. It wouldn't be worth it for me to put up with extra Vance crap, but it could be a good professional discussion if the ip is willing to entertain it without holding it against you. Just out of curiosity, about what airspeed were you at when you did the max range aoa (if you remember)?

 

[Tom]

I'm specifically talking about my single engine prop-driven T-6A Texan II.

And in the case in question, I'm talking about a scenario where I've lost the engine completely and am trying to stretch it out and make it to a runway. The AF says t oignore my AOA gauge and just always fly 125 for best range no matter what the AOA indicates (then why have a little triangle labeled Max Range?)

From my limited experience here is what I think. In an instance of a complete loss of power, initial students are taught to establish Vglide (which I believe correlates to your 125). This is a speed at which the lift to drag ratio is the best. This speed can change with weight, CG, etc. due to different lift requirements and resulting drag created. An aircraft's speed in the situation is effected only by AoA in straight and level flight.

Your situation indicates that my conjecture is correct. In the argument for training though I can understand the idea of teaching 125 (or whatever Vglide corresponds to). In an emergency situation with a low time pilot at the controls, a training organization may want to dumb down the idea in the hope that the pilot will fly the aircraft all the way to landing. New pilots have a problem of having their head inside the aircraft too much.

Then again, what's the first thing that goes through a pilot's head when he crashes?

The firewall.

 

[nittany03]

In the argument for training though I can understand the idea of teaching 125 (or whatever Vglide corresponds to). In an emergency situation with a low time pilot at the controls, a training organization may want to dumb down the idea in the hope that the pilot will fly the aircraft all the way to landing.

I would also add that at low airspeed it is very easy to overcontrol AOA when using it as a performance measure. When I was first learning the T-45, I had trouble overcontrolling the nose during stall recoveries by chasing AOA. Took me some practice to get soft enough hands to hold 1 unit AOA. Dunno if the T-6 is the same.