Thrust to Weight Ratios

[2bighorn]

You have confused me what you are defining as 1g. Is your definition of 1 g, that an object orbiting the earth is experiencing 1g? I'm not debating, just want to know your G definition.

Not sure where we went in different directions.

If you park a plane on tarmac horizontally, one axis G meter will show 1G, if you park it on the tail nose up it will show 0G, even though in both cases plane accelerates upwards at 1G relative to free fall, correct?

Or are we talking about another reference frame?

[hitech]

I'm just saying that the forces acting on airframe aren't necessarily the same as forces acting on a body (let's say pilot) inside the airframe.

Ok I'm lost again, pilot strapped to plane. Pilot is now part of airplane. Force acts on airplane, but not on the pilot?

HiTech

[2bighorn]

Ok I'm lost again, pilot strapped to plane. Pilot is now part of airplane. Force acts on airplane, but not on the pilot?

HiTech

Only forces acting on the pilot are weight and airframe.

[hitech]

Only forces acting on the pilot are weight and airframe.

I have never heard of a force named airframe.

I have heard of forces like lift,drag,thrust and weight.

All of which except weight are transmitted to the pilot threw an airframe.

But I do not believe an airframe is a force.

P.S. at this point we are just speaking of semantics.


HiTech

[Midway]

  <enters brainy think tank room>    <sees heated discussion>  <leaves brainy think tank room as fast as possible> 

[FLS]

Only at the top for a moment I think when the thrust runs out of steam.

Hitech is describing a special situation where the only thrust is from momentum and only gravity is decelerating you. I believe his point is that you won't feel weight in the decelerating zoom climb the same as you don't feel weight in freefall.

[2bighorn]

I have never heard of a force named airframe.

I have heard of forces like lift,drag,thrust and weight.

All of which except weight are transmitted to the pilot threw an airframe.

But I do not believe an airframe is a force.

P.S. at this point we are just speaking of semantics.


HiTech

Of course it's semantics. You know that I meant the force airframe exerts on the pilot, and if we are picky, you can't call it thrust, lift nor drag, since neither affects pilot directly, but only as a vector sum force resulting from others, minus loss incurring during the transfer ie deformation (straps), or even purposely built device such as shock absorbers/acceleration dampeners.

But lets keep it simple, any time you accelerate (relative to free fall) you feel G forces.

And if you answer the question I asked earlier, we're back in discussion, otherwise, we'll just talk by each other.

If you park a plane on tarmac horizontally, one axis G meter will show 1G, if you park it on the tail nose up it will show 0G, even though in both cases plane accelerates upwards at 1G relative to free fall, correct?

Or are we talking about another reference frame?

[FLS]

That's why climbers, when climbing those vertical walls, float? cos(90)=0.  Congrats, you've just invented anti-gravity.

You're just saying that thrust can't be greater than weight but really you know better.

[PuppetZ]

If I sum this up,

G load is the measure of acceleration of an airframe along a certain axis, going straight up and down, passing through the CG.
In certain flight regime, the instrumentation wont read the gravity as part of the total G load of an airframe. Level it read 1g, inverted -1g and vertical 0g. And everything in-between.
Gravity being universal, it's always felt along a certain axis, which is going from the center of gravity straight down to mother earth.

Soooooo....where does that leave me? I guess that I should avoid nose high turn if I want to optimize my turn rate as gravity will add to my turn instead of fighting me.

But this was interesting.

Now speaking of anti-gravity, when do we the claw back. T'was such a treat! 

[2bighorn]

You're just saying that thrust can't be greater than weight but really you know better.

You're just saying that Apollo astronauts didn't know about cos(90)=0 but you really know better.

[Lusche]

Interesting. I thought a zero G situation was that of a freefalling object. So if I'm in a plane climbing straight up, I'll be weightless?

Edit : I really dont get it. Do you define a G in a plane as a force acting straight down on the floor of the craft in level flight? If so it does make sense as depending on the planes attitude, gravity is going to act differently on your plane. Then by that definition, we could say a plane going straight up is experiencing 0g relative to that imaginary line coming perpendicular to the floor. Yet the pilot and airframe will still experience gravity but along a different axis. Does that even make sense?! I'm kinda comfused by this discussion.

With the correct throttle setting you would be feeling completely weightless/falling, or more correctly decelerating

I'm sure you all seen the pictures and vids of astronauts training  for zero-G in parabolic flights in airliners:



And that's the segment of the flight where they experience zero G:



As you can see, 0G begins while still climbing.

[FLS]

You're just saying that Apollo astronauts didn't know about cos(90)=0 but you really know better.

Are you wondering about the .3 G? Lift is .7 G. Thrust adds .3 G. Pilot and plane are at 1G.

[2bighorn]

As you can see, 0G begins while still climbing.

At that point plane is not really climbing, it's in state of inertial fall, similar to satellites orbiting the Earth. Simply said, it's in free fall but not toward the center of the Earth.

[Lusche]

At that point plane is not really climbing, it's in state of inertial fall, similar to satellites orbiting the Earth. Simply said, it's in free fall but not toward the center of the Earth.

Strange definition of climbing there 

As long as I see a plane going UP I would call it climbing.

[2bighorn]

Strange definition of climbing there 

As long as I see a plane going UP I would call it climbing.

In that graphic, the flight path is not illustrated well. Plane does not climb when astronauts experience 0G.