Don't Snap Roll A Hawker

Pilot Fighter said:
Normally, with aircraft, we are talking G's relative to the airframe.
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Well, everything in the airplane is relative to the wings, which are directly connected to the airframe. If the wings are at +1G, everything else in and connected to the inside of the airframe is at +1G. Sideloads (roll loads) will be felt, but in exactly the same way as they always are during a turn.
Now... there is that theory that if all the Pax jump out of their seats just before touchdown, we can lower our landing weight...;)
 
Crop Duster said:
You mistake me son, I live for this kind of discussion. I've got scars from old AOCS AFNA discussions. Best part is, it's not a fight... lots of smart folks here... I might learn something.
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And usually I would agree with that sentiment...
 
Crop Duster said:
You mistake me son, I live for this kind of discussion. I've got scars from old AOCS AFNA discussions. Best part is, it's not a fight... lots of smart folks here... I might learn something.
Click to expand...
Upright or inverted in level flight, an aircraft is experiencing 1G.

G's have a vector component. So, at 1G, you would expect fluids to accumulate in the direction of the vector component within a reservoir, just as you would expect an aircraft generating no lift to fall in the direction of that vector.
 
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Pilot Fighter said:
Upright or inverted in level flight, an aircraft is experiencing +1G.

G's have a vector component. So, at 1G, you would expect fluids to accumulate in the direction of the vector component within a reservoir, just as you would expect an aircraft generating no lift to fall in the direction of that vector.
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Which, if I'm understanding you correctly, is precisely why I can keep water (or any other fluid) in an inverted bucket, and by extension, why I don't need any "inverted" systems to keep my engine running while doing a properly executed +1G maneuver of any kind.
I'm not talking about sustained inverted flight. That's negative and a whole different bucket o' fish.
 
Crop Duster said:
Which, if I'm understanding you correctly, is precisely why I can keep water (or any other fluid) in an inverted bucket, and by extension, why I don't need any "inverted" systems to keep my engine running while doing a properly executed +1G maneuver of any kind.
I'm not talking about sustained inverted flight. That's negative and a whole different bucket o' fish.
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Yes, we agree. The case of an inverted aircraft forces us to be strict in our definitions and continue to use the same vector. If we built an aircraft that was symmetrical, top and bottom, the force of gravity is really the same even though we could run out of fuel without an inverted system, different load factor (dimensional).

I just realized that I don't like this subject without being able to draw pictures.
 
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Crop Duster said:
Which, if I'm understanding you correctly, is precisely why I can keep water (or any other fluid) in an inverted bucket, and by extension, why I don't need any "inverted" systems to keep my engine running while doing a properly executed +1G maneuver of any kind.
I'm not talking about sustained inverted flight. That's negative and a whole different bucket o' fish.
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I clarified my comment a few posts after the one you replied to. I was posting on my phone and it cut off the part where I was referencing sustained inverted flight even if you use +1G to get there.
 
mikecweb said:
I think a more important debate is whether or not this should be shared on a public forum. The bravado or whatever want to call it, and notion that you can willingly break regulations because you are *I don't have the education to emote without using a curse word* super pilot is sad. Are you going to fall out of the sky for rolling a airplane, probably not. You want to brag about it, get off my lawn.
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Personally, I wouldn't, but the willingness to do so is very strange.
 
These last few posts has helped me learn something, rather explained physics and now I know why the lav juice spills out when I roll the Gulfstream.

Thank you, Mr Wizard.
 
Crop Duster said:
I get where you are going, and I certainly agree that the best reason NOT to do aerobatics (of any kind) in a non aerobat airplane is that PILOTs screw up.
But lets be real clear here and go back to basic aerodynamics 101. An airplane in controlled flight DOES NOT CARE where the earth is. All the airplane cares about is where the relative wind is. To an airplane, rolling out of a +1G turn to the left is exactly the same as entering a +1G turn to the right. To an airplane, being "inverted" at +1G is exactly the same as being "upright" at +1G. At +1G there IS NO INVERTED to an airplane (in the air)... only to a pilot. Control surfaces, interference drag, stability... NONE of those change to the airplane if you are actually flying "upside down" at +1G. Again, the airplane doesn't know it. "Upside down" is a human perception, not an airplane's. A wing is just a machine that does work based on airflow over it. We control the work it does by controlling that airflow. The airflow, and consequent work, in a positive G flight regime is NOT related to its position relative to the earth.
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Right, and what I was trying to say (which maybe didn't come through) is that if you're not super pilot and don't do a perfect 1G roll, you will start getting relative wind angles, interference drag and potential stability effects that the aerodynamics people weren't necessarily obligated to look at. It's more about the potential for surprise of something unexpected happening half way through the maneuver - and how the pilot reacts to that surprise - rather than any concrete structural or aerodynamic limit.

I'm not advocating breaking FARs and doing aerobatics in a non-aerobatic airplane either, just saying that test pilots do envelope expanding maneuvers all the time, and the trick is to not do dumb stuff when unexpected things happen.

Edit: I can see this thread has devolved into people talking about all kinds of random stuff... Sustained inverted flight... Fluids pooling in different parts of tanks, etc. To be clear, we started talking about a QUICK +1G aileron roll with no sustained inverted flight. When flown correctly your butt stays on the seat the whole time, Bob Hoover can pour his tea, etc. In that case the relative wind is the same as it always was and there's no reason to worry about fuel or oil pooling in weird places it shouldn't. But then you've probably flown with someone who's like "hey watch this!" and rolls the airplane and you get that lurching feeling in your stomach upsidedown and your butt comes off the seat. At that point you're at less than +1G. It's a subtle argument but since people make mistakes and don't always fly maneuvers perfectly, that's when I would start to worry about something weird happening.
 
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inigo88 said:
Right, and what I was trying to say (which maybe didn't come through) is that if you're not super pilot and don't do a perfect 1G roll, you will start getting relative wind angles, interference drag and potential stability effects that the aerodynamics people weren't necessarily obligated to look at. It's more about the potential for surprise of something unexpected happening half way through the maneuver - and how the pilot reacts to that surprise - rather than any concrete structural or aerodynamic limit.

I'm not advocating breaking FARs and doing aerobatics in a non-aerobatic airplane either, just saying that test pilots do envelope expanding maneuvers all the time, and the trick is to not do dumb stuff when unexpected things happen.

Edit: I can see this thread has devolved into people talking about all kinds of random stuff... Sustained inverted flight... Fluids pooling in different parts of tanks, etc. To be clear, we started talking about a QUICK +1G aileron roll with no sustained inverted flight. When flown correctly your butt stays on the seat the whole time, Bob Hoover can pour his tea, etc. In that case the relative wind is the same as it always was and there's no reason to worry about fuel or oil pooling in weird places it shouldn't. But then you've probably flown with someone who's like "hey watch this!" and rolls the airplane and you get that lurching feeling in your stomach upsidedown and your butt comes off the seat. At that point you're at less than +1G. It's a subtle argument but since people make mistakes and don't always fly maneuvers perfectly, that's when I would start to worry about something weird happening.
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Hoover's tea pouring flight was a barrel roll, a graceful maneuver in which the vector of the load factor keeps you squarely in your seat, pretty constant positive g load.

A quick aileron roll can knock the slobber out of your mouth, as your big head chases your body.
 
Pilot Fighter said:
Hoover's tea pouring flight was a barrel roll, a graceful maneuver in which the vector of the load factor keeps you squarely in your seat, pretty constant positive g load.

A quick aileron roll can knock the slobber out of your mouth, as your big head chases your body.
Click to expand...

Here's what I look like in a point aileron roll...
dog-drool_New.jpg
 
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