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AOA, Can someone explain this to me?
- Thread starter Purdue
- Start date
Do you guys --- these days --- call it an "indicator" or an "indexer" .... ???
The AOA indexer and AOA indicator are two different things...
At least in the A4...
A4 Skyhawk Angle of Attack System
View attachment 3811
At least in the A4...
A4 Skyhawk Angle of Attack System
View attachment 3811
The AOA stuff in API is pretty basic and has some assumptions that don't 100% agree with reality. That said, I think your IP might be full of sh!t. He was spouting gouge and slapping your peepee for not knowing gouge. Usually when they quote random gouge numbers (0-2 units AOA??), they are pulling it from a handout they got at PIT. I think it's available on the gouge CD. You might look into that. The correct answer is to reference the diversion range summary in the pocket checklist. I'm sure you know this already or you never would have made it past the 15 day program.
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.
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.
I think you mean the indexer. That doesn't matter, since you don't use the indexer outside of the pattern. On the other hand, the AOA gauge always works.
NavyLonghorn
Registered User
No AOA indication atall in the Tweet. So totally new concept to some of those guys I bet.
I think what A-4s is saying is right on the money. Obviously I'm not an expert, but I'll go ahead and throw in my .02 just for fun.
M/E is simply, how can I stay in the air for the maximum amount of time? The answer HAS to be to have the lowest rate of fuel consumption. That means maximize L/D ratio so you can stay in level flight with the least amount of wasted energy. Since L/D shouldn't change with altitude, this should be a constant AoA
M/R means get as far as I can before my fuel runs out. However, since engine performance DOES change with altitude, it seems very possible to me that getting the most DISTANCE from the plane does not mean flying at max L/D. In this case, the best L/D for M/R could depend on altitude, which is why the AoA could be different. If not, then maybe they are factoring in the fact that at a higher altitude, you can glide. Wheras at a lower altitude, you can't
My attempt at an explanation.
M/E is simply, how can I stay in the air for the maximum amount of time? The answer HAS to be to have the lowest rate of fuel consumption. That means maximize L/D ratio so you can stay in level flight with the least amount of wasted energy. Since L/D shouldn't change with altitude, this should be a constant AoA
M/R means get as far as I can before my fuel runs out. However, since engine performance DOES change with altitude, it seems very possible to me that getting the most DISTANCE from the plane does not mean flying at max L/D. In this case, the best L/D for M/R could depend on altitude, which is why the AoA could be different. If not, then maybe they are factoring in the fact that at a higher altitude, you can glide. Wheras at a lower altitude, you can't
My attempt at an explanation.
Indexer. I meant indexer. The word completely slipped my mind when posting.
I accept your heartfelt apology and will support you while you bear the burden of your shame and humiliation ... question: how does it feel to be "old" ....
... ???
ACTUALLY ... we X-checked the throttles with the book ... ALWAYS .... 'cause they occasionally don't do it "right" ... and once in a while we're dispatched WITHOUT one of those God-given gifts to Aviation ... this one called "auto-throttles" ... and once in a while, based on 25 years experience ... I could do it "better" (fuel burn, forward speed, vis-a-vi competing traffic) than the "gee-whiz" stuff that Boeing engineers thought we needed.
Bottom line: you HAVE to be smarter than the airplane. And by extension ... smarter than the engineers that designed it.
...But close to the ground ... ??? I ALWAYS used airspeed and nose attitude (and to a lesser degree, the altimeter/other visual cues) ... as I could follow the AOA guage right into the ground ...
As I'm sure you are aware, we're talking about a different kind of flying.
As for the pattern, I still find the indicator more helpful than the indexer, but again, different (read: lighter/slower) airframe.
The IP was right that the airspeed schedule in the PCL changes with altitude (IAS changes much more than TAS). In these tables, the airspeed to be flown depends only on the altitude and drag index. The airspeed to be flown does not take into account different fuel loads at a given altitude. If you were to fly L/Dmax AOA you would not get these airspeeds at altitudes other than 31k and some nominal fuel state. If you look closely at the trends in the recommended TAS and IAS for each altitude, niether changes linearly with altitude changes. The TAS oscillates back and forth. This seems to indicate some more complex factors than the simple changes in TAS expected due to changes in atmospheric density while flying constant AOA.
The bottom line is that it looks like flying your 4.9 Units isn't the approved and flight tested solution to diverts. The tables in the PCL are based on constant airspeed, which appears to coincide with L/Dmax only at 31k.
Oh yeah, up there in Enid, you have a good chance of having a 100+ knot wind in the MOA from the jet stream in the winter. That can make much of this moot anyway.
In any case, you will be flying an airspeed from a chart, not a gouge AOA.
The bottom line is that it looks like flying your 4.9 Units isn't the approved and flight tested solution to diverts. The tables in the PCL are based on constant airspeed, which appears to coincide with L/Dmax only at 31k.
Oh yeah, up there in Enid, you have a good chance of having a 100+ knot wind in the MOA from the jet stream in the winter. That can make much of this moot anyway.
In any case, you will be flying an airspeed from a chart, not a gouge AOA.
Sure... but only for some of you .... the "bottom line" (above) was provided for those who participate in an arena of flight that you do not participate in ...
Awesome...Sure... but only for some of you .... the "bottom line" (above) was provided for those who participate in an arena of flight that you do not participate in ...
Gator, you gotta agree you opened up for that comeback