Author Topic: Get rid of tail heavy physics  (Read 5003 times)

Offline Dream Child

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Get rid of tail heavy physics
« on: September 20, 2009, 06:46:15 PM »
Real WWII planes, in almost all circumstances, are nose heavy, so why does the tail always drop when losing the horizontal stabilizers? Though this does provide some good laughs if I lose the stabilizers on my FM-2 in the dueling arena, where I figured out I could make a continuous right hand turn without them if the flaps were down, and have all sorts of people yell about hacking the game... in real life, most of the time, the horizontal stabilizer and elevators are pushing down on the back of the airplane to make it fly, so if you lose them, the nose would drop, especially since you've lightened the tail even more by removing the extra weight.

While I don't want to get too realistic with the physics, I'd like to see this one fixed.

Offline guncrasher

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Re: Get rid of tail heavy physics
« Reply #1 on: September 20, 2009, 06:51:47 PM »
I always thought that plane with no elevators would dive faster than a pony running away from a c47.  which brings another related item, why how can a plane with 1/2 a wing still be able to fly at full speed.

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Offline AirFlyer

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Re: Get rid of tail heavy physics
« Reply #2 on: September 20, 2009, 07:31:56 PM »
I have a few guesses on this, and I don't think it has a whole lot to do with weight, mind I'm not fully informed on airplane physics so I could be wrong.

Whenever I see a plane go nose up after I've just taken off the Hor. Stabs. they are generally mostly level, or, going up(ish). When this happens my guess is your planes wings are still creating lift, your Hor. Stabs. are no longer creating that nice stability like the name implies, and physics just put your nose up from the lift of your wings. Stall ensues and eventually like the old saying implies, what came up is now coming back down.

Again, just my guess, and by no means right.
« Last Edit: September 20, 2009, 07:33:27 PM by AirFlyer »
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Offline OOZ662

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Re: Get rid of tail heavy physics
« Reply #3 on: September 20, 2009, 07:36:59 PM »
From my point of view, a plane without horizontal stabs becomes just like a leaf. It flutters up until the air over the wings is reversed, at which point they just slide downward as they're like a razor to the air.

But, that's just my theory.
A Rook who first flew 09/26/03 at the age of 13, has been a GL in 10+ Scenarios, and was two-time Points and First Annual 68KO Cup winner of the AH Extreme Air Racing League.

Offline Dream Child

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Re: Get rid of tail heavy physics
« Reply #4 on: September 20, 2009, 07:55:50 PM »
I have a few guesses on this, and I don't think it has a whole lot to do with weight, mind I'm not fully informed on airplane physics so I could be wrong.

Whenever I see a plane go nose up after I've just taken off the Hor. Stabs. they are generally mostly level, or, going up(ish). When this happens my guess is your planes wings are still creating lift, your Hor. Stabs. are no longer creating that nice stability like the name implies, and physics just put your nose up from the lift of your wings. Stall ensues and eventually like the old saying implies, what came up is now coming back down.

Again, just my guess, and by no means right.

Yes, you're still creating lift, but the center of gravity is forward of the center of lift, so nose goes down, not up. Remember, in real life, you're pushing down on the tail to make the plane fly. Stop pushing down on the tail and the nose drops, and in this case probably oscillate badly after that as there are no stabilizers to dampen things out.

Offline Dream Child

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Re: Get rid of tail heavy physics
« Reply #5 on: September 20, 2009, 07:57:32 PM »
From my point of view, a plane without horizontal stabs becomes just like a leaf. It flutters up until the air over the wings is reversed, at which point they just slide downward as they're like a razor to the air.

But, that's just my theory.

Well, it would lose stability on one axis, and would probably oscillate badly, but would still end up nose down, as the center of gravity is in front of the center of lift.

Offline OOZ662

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Re: Get rid of tail heavy physics
« Reply #6 on: September 20, 2009, 07:59:19 PM »
Looking at an aircraft simply from the aspect of CoG is like looking at how a computer works by examining a capacitor on the motherboard.
A Rook who first flew 09/26/03 at the age of 13, has been a GL in 10+ Scenarios, and was two-time Points and First Annual 68KO Cup winner of the AH Extreme Air Racing League.

Offline Chalenge

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Re: Get rid of tail heavy physics
« Reply #7 on: September 20, 2009, 08:00:12 PM »
It may not look right but I considered it for a while after the last collision I had with a tailess airplane (I would call it debris) and my conclusion was that the pitching moment takes precedence over the other forces at work once the tail parts company. Its lift on the tail that keeps the nose down and counters the pitching moment normally.
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Offline Knite

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Re: Get rid of tail heavy physics
« Reply #8 on: September 20, 2009, 08:17:48 PM »
Actually, an aircraft in flight losing the horizontal stablizers WOULD pitch nose up. It's not a factor of center of gravity, but how wings work to create lift. (for instance, an aircraft wing is not perfectly flat, not symmetrical in the vertical plane). There is a reason for that.

Probably best I just link to NASA =P

http://www.grc.nasa.gov/WWW/K-12/airplane/elv.html
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Offline AirFlyer

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Re: Get rid of tail heavy physics
« Reply #9 on: September 20, 2009, 08:20:11 PM »
Actually, an aircraft in flight losing the horizontal stablizers WOULD pitch nose up. It's not a factor of center of gravity, but how wings work to create lift. (for instance, an aircraft wing is not perfectly flat, not symmetrical in the vertical plane). There is a reason for that.

Probably best I just link to NASA =P

http://www.grc.nasa.gov/WWW/K-12/airplane/elv.html


Interesting, from what I got out of that I was semi-right anyways.
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Offline Dream Child

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Re: Get rid of tail heavy physics
« Reply #10 on: September 20, 2009, 08:49:35 PM »
Actually, an aircraft in flight losing the horizontal stablizers WOULD pitch nose up. It's not a factor of center of gravity, but how wings work to create lift. (for instance, an aircraft wing is not perfectly flat, not symmetrical in the vertical plane). There is a reason for that.

Probably best I just link to NASA =P

http://www.grc.nasa.gov/WWW/K-12/airplane/elv.html


Umm...no, not normally. It's a factor of center of gravity vs center of lift. If I have to push down on the tail to keep the nose of the plane up, and then I lose that push, the nose goes down. While the math is a bit messy, the concept is not.

Offline Dream Child

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Re: Get rid of tail heavy physics
« Reply #11 on: September 20, 2009, 08:56:26 PM »
Looking at an aircraft simply from the aspect of CoG is like looking at how a computer works by examining a capacitor on the motherboard.

Umm...no, not even close. I'll say this as simply as I know how. Under normal flying conditions, one has to push the tail down to make the plane fly level. This is because the CoG is in front of the Center of Lift (CoL). If I lose that downward push on the tail, the tail will rise, and subsequently, the nose will drop. Most, if not all, planes are cabable of operating with the CoG behind the CoF, but that is not normal operation, and the design is for normal operation with the CoG in front of the CoL.

Offline Chalenge

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Re: Get rid of tail heavy physics
« Reply #12 on: September 20, 2009, 08:59:08 PM »
I think this fellow discusses aftward CGs (nose heaviness) and pitching moments rather well but consider well what he is saying (the opposite of what I suggested):

http://ciurpita.tripod.com/rc/rcsd/lowSpeedStability/lowSpeedStability.html
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Offline BnZs

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Re: Get rid of tail heavy physics
« Reply #13 on: September 20, 2009, 09:00:39 PM »
Rather academic whats happens to your airplane after the stabs are shot loose, unless you are also saying this "tail-heavy" modeling 1. has an effect when planes still in one piece are maneuvering and 2. that this is innacurate.
« Last Edit: September 20, 2009, 09:14:54 PM by BnZs »
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Offline Chalenge

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Re: Get rid of tail heavy physics
« Reply #14 on: September 20, 2009, 09:03:23 PM »
Rather academic whats happens to your airplane after the stabs are shot loose, unless you are also saying this "tail-heavy" modeling 1. has an effect when planes still in on piece are maneuvering and 2. that this is innacurate.

I would agree except for those dreaded collisions being forced upon me by debris flopping up into my face.

I think what we see online is accurate as far as airspeed is represented but that after speed drops off the nose should then fall... but why not setup an experiment and see for yourself?
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