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  #11  
Old 01-25-2016, 08:53 AM
sblack sblack is offline
 
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Just to be clear, it is pitch angle, not AOA, that is a factor in fuel flow. Pitch is related to the earth, so it is AC orientation relative to the gravity vector. AOA is related to the airstream. An aircraft can have a stall AOA at 0 deg pitch. AOA has no direct impact on the fuel system.
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  #12  
Old 01-25-2016, 10:24 AM
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Guy Prevost Guy Prevost is offline
 
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I had that happen once during testing, because I forgot to push the mixture forward from its previous very lean position for high altitude cruising and LOP testing.

Guy
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  #13  
Old 01-25-2016, 10:29 AM
TS Flightlines TS Flightlines is offline
 
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Whatever the issue--Guilherme my friend be safe!!!!
Maybe we need to put a Williams FJ44 on your RV so you'll feel more comfortable!



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  #14  
Old 01-25-2016, 10:58 AM
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Alex

That's what I am pressuming as well
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  #15  
Old 01-25-2016, 11:00 AM
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Tom

Those jet engines aren't funny������like our lycosauros
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  #16  
Old 01-25-2016, 11:18 AM
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beav beav is offline
 
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This happened to me as well during Phase 1 flight testing. The issue turned out to be an overly rich idle mixture. Make sure you're getting the recommended 50rpm rise on shutdown to ensure your idle mixture is set correctly.
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  #17  
Old 01-25-2016, 06:10 PM
BillL BillL is offline
 
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Quote:
Originally Posted by sblack View Post
Just to be clear, it is pitch angle, not AOA, that is a factor in fuel flow. Pitch is related to the earth, so it is AC orientation relative to the gravity vector. AOA is related to the airstream. An aircraft can have a stall AOA at 0 deg pitch. AOA has no direct impact on the fuel system.
So what does the fuel see from tank level to mechanical pump when the plane is at 4 G's vertical into a loop? Where is the vector? Wouldn't AOA be more applicable here, or should we just do the vector calculations and get the relative "height" of the fuel column? Is it pitch?
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  #18  
Old 01-26-2016, 07:30 AM
sblack sblack is offline
 
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Quote:
Originally Posted by BillL View Post
So what does the fuel see from tank level to mechanical pump when the plane is at 4 G's vertical into a loop? Where is the vector? Wouldn't AOA be more applicable here, or should we just do the vector calculations and get the relative "height" of the fuel column? Is it pitch?
Hmm I might have engaged keyboard before brain there. The true longitudinal angle that the fuel sees is the angle between whatever your pitch reference is, say the top longeron, and the resultant acceleration vector which is the vector sum of the vertical and longitudinal accelerations and gravity, or as we call it in engineering nomenclature Nx, Ny and g. But this is over-complicating it. In a 4g loop it would be the vector sum of the acceleration of the airplane in pitch about the center of the loop (Vsquared/r), the longitudinal acceleration which would probably be -ve on the way up and the gravity vector so it would depend where you were in the loop and yes, angle of attack would figure into that because it is the difference between your pitch datum and the flight path. But this is all academic. When you do your fuel flow test in preparation for first flight you generally use your max climb pitch attitude.

Interestingly, if you look at the fuel angle in the tank on the runway during the takeoff roll, when the airplane is accelerating, and the same angle in the tank on climb at constant speed, they are the same. I've done this simulation for large airplanes.
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  #19  
Old 01-26-2016, 08:58 AM
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bobmarkert bobmarkert is offline
 
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Default Engine quit during spin

A few weeks ago I had the same problem during a 6 turn spin. I fly out of KBJC outside Denver so the terrain is very high. I was at 10,000' msl / 4,000' agl. Here is the bottom line for me; I have a light weight prop and high compression engine and I was too rich for the altitude I was at when I did my spins. Here in Denver we lean for a normal takeoff. At 10,000, leaning aggressively fixed my problem. What altitude were you at when you did your stalls? This may or may not be a component of your issue.

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