Doing aerobatics in bomb-loaded bombers

[bozon]

#1, when you are standing on the ground, you are in effect, pulling 1 G, if you jump up into the air, you are now pulling a negative G.

When jumping in the air you are in free-fall, hence 0 G, not negative. Negative G would be jumping into the air with a rubber band stretching after you and pulling you down in addition to gravity.

Just sayin'

Since each additional g adds the total aircraft weight to the wing load you just have to reduce max g by 1 to stay within the wing limit.

Good luck flying a 1g loop.  I hope you mean keep some positive g when inverted.   

You can fly a loop and keep positive G through it. For example, you can start with a 3G pull, down to 2G when crossing the vertical and 1G when inverted, then build up G again as you accelerate downward on the other side. This way you have a constant 2G centripetal acceleration throughout, and keep G positive. However the loss of speed in the climb will not make this a perfect circle - more like an inverted Greek gamma shape.

[FLS]

There is no negative g, it's just a different vector. 

You don't need 1 g inverted, any radial g will keep you in the seat.

[earl1937]

Since each additional g adds the total aircraft weight to the wing load you just have to reduce max g by 1 to stay within the wing limit.

Good luck flying a 1g loop.  I hope you mean keep some positive g when inverted.   

I never said anything about a 1 g roll, but have done many 1.5 g barrel rolls, which is very easy to do. If you are not pulling at least a 1/2 G, every loose object  in the aircraft is going to fly up in your face, including the dirt and dust in the floor.

[Brooke]

Bet that was great seeing/hearing Tillman speak.

It was, and I was really grateful that he showed up to moderate one of the discussion panels.

Also, many of the pilots' stories have been absolutely amazing.  I've heard stories from combat pilots of most of the US combat aircraft in WWII (P-51, P-47, P-38, P-40, F4U, F6F, TBM, SBD, B-29, B-17, B-24, B-25, P-61) and some RAF planes (Spitfire, Mosquito, Beaufighter, Wellington), pilots who gained aces status in P-51's (Bud Anderson and others), P-47's (Steve Pisanos, George Novotny, and others), P-38's (George Chandler and others), F6F's (Hamilton McWhorter and others), F4U (Dean Caswell and others), and the Mosquito (Lou Luma), every theater, pilots who participated in the Battle of Midway (including Harry Ferrier, who was on the only TBM to make it back to Midway), the Marianas (F6F pilots and TBM pilot Warren Omark, who put a torpedo into the Hiyo), Market Garden (Spitfire pilot Witold Herbst), North Africa, bombing Tokyo, over Germany, France, and Italy, different roles (fighter, fighter-bomber, divebomber, torpedo bomber, bomber, recon), a guy who was on the USS Bunker Hill when it was hit by the kamikazes, a guy who shot down an Me 262 (Clayton Gross), a guy who shot down an Me 163 (Art Jeffrey).

The Museum of Flight near Seattle has been an amazing place.  I feel very lucky.

[earl1937]

When jumping in the air you are in free-fall, hence 0 G, not negative. Negative G would be jumping into the air with a rubber band stretching after you and pulling you down in addition to gravity.

Just sayin'
You can fly a loop and keep positive G through it. For example, you can start with a 3G pull, down to 2G when crossing the vertical and 1G when inverted, then build up G again as you accelerate downward on the other side. This way you have a constant 2G centripetal acceleration throughout, and keep G positive. However the loss of speed in the climb will not make this a perfect circle - more like an inverted Greek gamma shape.

OK, now I am confused! Are you saying that if you are inverted and you push forward on stick, you will not be pulling a negative G? I believe it was Einstein, who while talking about relativity, stated that anything that moves away from the center of the earth, is in effect, in a negative G situation., Hence, if you jump off the ground, as you are going up, you are in a negative situation. Maybe that was a poor analogy I used, but the principal is the same. Now if you are doing a spilt S, while you are not working aginst gravity, you now have centrfical  force which comes into play, which applies G forces, but is generated in a different way.  

[FLS]

I never said anything about a 1 g roll, but have done many 1.5 g barrel rolls, which is very easy to do. If you are not pulling at least a 1/2 G, every loose object  in the aircraft is going to fly up in your face, including the dirt and dust in the floor.

Earl the 1g comment was for Karnak. I would expect at least 4 g coming out of a loop and Karnak described holding 1 g throughout a loop.

[Cthulhu]

Guys, the uses of "g's" to describe the magnitude of inertial loads (and that's what maneuvering loads are) is purely a convention. The presence, or absence, of a gravitation field while you're making those maneuvers is largely secondary. You can pull a 100 g turn in the void of space (well your vehicle could..... you'd be a lump of Jello on the floor    )

Yes you can do a loop and experience zero "g" at the top (but only within a gravitaion field like the Earth's), but it will only be for a moment.

Yes, there is such a thing as negative g's, but it's just another convention (a reversal of the longitudinal acceleration vector relative to the coordinate system of the aircraft as FLS said).

[earl1937]

Earl the 1g comment was for Karnak. I would expect at least 4 g coming out of a loop and Karnak described holding 1 g throughout a loop.

Sorry sir! My bad, I always enjoy your posts and  you do for training people in this great game!

[FLS]

Sorry sir! My bad, I always enjoy your posts and  you do for training people in this great game!

No worries I've misread a few posts myself.   

[bozon]

OK, now I am confused! Are you saying that if you are inverted and you push forward on stick, you will not be pulling a negative G? I believe it was Einstein, who while talking about relativity, stated that anything that moves away from the center of the earth, is in effect, in a negative G situation., Hence, if you jump off the ground, as you are going up, you are in a negative situation. Maybe that was a poor analogy I used, but the principal is the same. Now if you are doing a spilt S, while you are not working aginst gravity, you now have centrfical  force which comes into play, which applies G forces, but is generated in a different way.  

I never said anything about pushing the stick. What I said translates to "you can yank on the stick and keep G>1 throughout the loop", but it will not come out like a nice circle. Easy to demonstrate in AH, every spit 2-weeker does it as his main ACM.

0G means free-fall. The direction of travel makes no difference - a stone thrown upward is at free-fall even when it is still going up. For a pilot like yourself: G=L/Mg using just scalar numbers and regardless of the gravity vector. Everything that is traveling through the air and does not produce lift (L=0) is pulling 0G and flies ballisticly. So, if you jump up off the ground you are at 0G till you hit the ground again.

Now regarding relativity - in general relativity, being "stationary" means 0G, i.e. free-fall. So, if you are NOT falling and are standing on solid ground you are actually accelerating "up" from earth at 1g (lower case "g"=10 m/s^2 and has nothing to do with "lift" in the aeronautical sense). You can call this negative acceleration if you define the positive direction towards the earth's center, so you are now at -1g and are moving away from earth's center in space-time.

General relativity originated from the notion that locally one cannot distinguish between gravity and acceleration, hence "gravity" is in practice acceleration. Ironically, Einstein's theory that is supposed to explained gravity does not have a gravitational force in it at all.

[FLS]

Aren't you guys just disagreeing about your frame of reference? After you jump you decelerate, stop, and accelerate in the opposite direction until the ground stops you. As Cthulhu pointed out 0 g refers to load factor. We are always subject to gravity.

[Widewing]

Aren't you guys just disagreeing about your frame of reference? After you jump you decelerate, stop, and accelerate in the opposite direction until the ground stops you. As Cthulhu pointed out 0 g refers to load factor. We are always subject to gravity.

To attain zero g, you must descend at the rate of gravity. This can be seen using an strain gauge type accelerometer w/amplifier and an Oscilloscope. Attach the accelerometer to something you can simply let fall. We use vertical drop test machines for testing dynamic response to impacts. While sitting in normal gravity, the accelerometer will have a voltage output that equates to 1g. When it is released, the output voltage nearly goes to zero. It can never attain zero, because there are always factors preventing it. Aero drag, very slight friction on the Teflon guide bushings, etc, all contribute to not dropping at the rate of gravity. It comes very close, though.

An aircraft can attain zero g by easing nose down and losing altitude at the rate of gravity. Fighter pilots call this, "unloading". It minimizes induced drag and maximizes acceleration with minimal loss of altitude.

[Cthulhu]

To attain zero g, you must descend at the rate of gravity. This can be seen using an strain gauge type accelerometer w/amplifier and an Oscilloscope. Attach the accelerometer to something you can simply let fall. We use vertical drop test machines for testing dynamic response to impacts. While sitting in normal gravity, the accelerometer will have a voltage output that equates to 1g. When it is released, the output voltage nearly goes to zero. It can never attain zero, because there are always factors preventing it. Aero drag, very slight friction on the Teflon guide bushings, etc, all contribute to not dropping at the rate of gravity. It comes very close, though.

An aircraft can attain zero g by easing nose down and losing altitude at the rate of gravity. Fighter pilots call this, "unloading". It minimizes induced drag and maximizes acceleration with minimal loss of altitude.

I'm surprised you didn't use the "Vomit Comet" as an example of zero g.

[TheCrazyOrange]

Correct me if I'm wrong, but isn't going up at any rate actually increasing the G's experienced? This being the case, isn't a rock still traveling up still experiencing G>0?

[Karnak]

Earl the 1g comment was for Karnak. I would expect at least 4 g coming out of a loop and Karnak described holding 1 g throughout a loop.

I didn't mean to imply that it was possible to do so.  I was being overly generic I fear.  Any pull out is going to be more than 1G, well, any pull out on Earth.  If somebody ever does on on Venus or Titan they will be able to keep it under 1 G if they are gentle enough.