How does the F4U-1A beat the Spit 16

[Masherbrum]

Thorism wrote:

The only thing that changes the direction of your Vel vector is lift.

And hence we are talking about turn radius & turn rate as I have stated before.

Bust out some poster board or flash cards, then he might grasp the concept Dale.   

[Ack-Ack]

once again not exactly true is it? 

What part isn't exactly true?  That you have no idea how flaps work or you haven't provided any proof how any parts of the flight model are incorrect?


ack-ack

[boomerlu]

Thorsim, flight modelling is the realm of Physicists, Aero Engineers, and Applied Mathematicians. It is too complicated for common sense. Given that you have no aero-credibility otherwise, your appeals to common sense hold no water against these guys who do have such credibility. If you are going to sensibly argue, you MUST learn the math behind it and use math to demonstrate it.

It is NOT sufficient to quote an aero-expert or pilot if you are not able to see the underlying mathematical reason. Quoting an aero-expert in this way means you have no idea if the quote is in the proper context.

I'm a physicist, I have no aero-qualification but I know enough to infer what I need. My post a few pages back clearly demonstrates that if you scale mass and wing area equally, the turn performance will be equal (assuming unpowered flight - if flight was powered, we would have to scale thrust equally but the result would still be the same). This is NOT necessarily possible in real life due to engineering constraints, but it is a THOUGHT EXPERIMENT so I've not applied engineering constraints.

Re:Hitech on roll rate. Sorry I still think in terms of torques and force of drag, but that's how I function. I doubt that'll change unless I really go get an aero masters. I see your point though - this is how I imagine it.

The linear velocity due to rolling at the wingtip is RR * wingspan. So the drag caused by rolling would be proportional to (RR * wingspan)^2. But the force available from the ailerons changing camber is only proportional to wingspan. Now that we have a force balance...
(RR * wingspan)^2 ~ wingspan
=> RR * wingspan ~ sqrt(wingspan)
=> RR ~ 1/(sqrt wingspan)

I know this is overly simplistic, but this is my physicists' approximation. I think this is what you mean by a longer wing creates a higher speed on the outside of the wing?

Edit: I'm trying to reconcile this with the lift equation, which is linearly proportional to wing area. So for that to work, scaling an aileron's size must only be able to affect a linear increase in its ability to change wing area?

[BnZs]

curious why you need to make the wing loading more on the f16 to make your point, as that is not at all what i am saying.

Make the *lift-loading* and thrust ratios on both airplanes equal and you will get equal results in turn performance, all other factors being equal. In reality, if you hung enough odds and ends on the aircraft bring the F-16's lift-loading up as high as that of the F-15s, you would also be tremendously reducing the thrust/weight and tremendously increasing the drag, so it wouldn't even be a contest.

[hitech]

Backing up to the base of this argument.

The original controversy.

Thorism wrote.

mass momentum and acceleration means more energy will be required(lost) changing the acceleration(turning) of a larger heavier object.  fancy flaps and fairie dust will not change that, no matter how bad the video gamers wish it would ...

While this on the surface is almost a correct statement, it negates a lot of things. Lets begin with a simple no motor , glide only case. You statement seems to imply the heaver object will slow down more quickly. This is not true at all, while correct all things being equal the heaver object will loose more energy, it has more energy stored, and hence the heaver object and lighter object will loose speed at the same rate if the L/D ratio and W/L ratio are the same. And hence if both are gliding would turn on the same downward spiral.

Now as we add a motor which plane will slow down more quickly will simply depend on the T/W ratio given the above case. I.E. who ever would climb the fastest would slow down the least.

So the problem some of us have with this statement it is a completely miss leading statement.

fancy flaps and fairie dust will not change that

And then thorsim statement got the ball rolling because he again back hands he belief that flaps are incorrect. (You said in a previous thread you were done with that topic, why do you bring it up again?[/quote]

Bnz wrote.

Correct. Weight by itself is no factor, but rather the ratio of weight (and drag) to lift and power. The Corsair possessed a rather heavy lift loading in comparison to Japanese aircraft and much greater speed than most opposition types, so it was very much best to keep it fast and boom and zoom in the PTO. In the AHII MA, the Corsair has a better lift loading than much of what it fights and is slower, so it becomes known as a turn fighter.

This statement.

Weight by itself is no factor, but rather the ratio of weight (and drag) to lift and power.

Is completely accurate, unlike thorsim's.[/quote]

And now it apears to me Thorsim has a problem because he switches from a debate of physics to a personal attack.

no the mistakes are yours, and whomever convinced you that the f4u4 could compete well in a maneuver fight vs. a spit 16.

all your statements below are suspect imo.  

Quote from: BnZs on Yesterday at 12:27:30 AM

Correct. Weight by itself is no factor ...  

Once again, the absolute size itself is irrelevant to performance. ...  

The F4U-1A is obviously the less draggy aircraft,  

since it goes faster despite having a lower power loading,  

this will primarily effect E retention in diving and zooming.  

The ratio of lift/weight in various configurations can be determined by comparing 1G stall speeds.  


your picture is cute but you have left out quite a few aircraft many of which out turned the spit 16 ...
spits 1-5, 109s E&Fs, yak 3?, laggs?, prolly the maccis, the hurris, some others as well ...

you sure are intrigued with near stall speed performance, however equating that with maneuverability in a fighter is comical, just ask any fighter pilot ...

it is you who needs to read because the only way to get around newton is "virtually" no matter what you see here.

if that were not so then the extras and SUs would not dominate aerobatics ...

t

And the persona attack begins, for what reason I can only guess. But BNZ is seems to be trying to describe things as accurately as possible, Thorsim seems to have barly any knowledge of the physics because of statements like this.

ure are intrigued with near stall speed performance, however equating that with maneuverability in a fighter is comical

Stall speed is a function of Weight/MaxLift  which has everything to do with turn radius.

HiTech

[thorsim]

and your lift is acting against the Vel vector to a new Vel vector ...

the force required to change the Vel vector of a heavier object is more than a lighter object.  

therefore the lighter object requires less force to change it's Vel vector.

now the question is could we switch the terms force and energy?

i think to a large extent we can, and there in lies the advantage of which i speak.

t

Thorism wrote:

The only thing that changes the direction of your Vel vector is lift.

And hence we are talking about turn radius & turn rate as I have stated before.

[thorsim]

so limit the trust available to the f15 and add some drag then make your case.

Make the *lift-loading* and thrust ratios on both airplanes equal and you will get equal results in turn performance, all other factors being equal. In reality, if you hung enough odds and ends on the aircraft bring the F-16's lift-loading up as high as that of the F-15s, you would also be tremendously reducing the thrust/weight and tremendously increasing the drag, so it wouldn't even be a contest.

[boomerlu]

now the question is could we switch the terms force and energy?

i think to a large extent we can, and there in lies the advantage of which i speak.

Pick up a high school physics textbook. Your butchery of the subject is quite comprehensive.

Edit: to be clear, a more massive object also CARRIES more energy than a smaller object for the same velocity. In a turn, a more massive airplane with correspondingly larger wing area will lose the same PROPORTION of energy as a smaller airplane with a correspondingly smaller wing area, everything else the same. Therefore the more massive aircraft will lose the same amount of airspeed as the smaller one as per the kinetic energy equation K = m v^2 with K the kinetic energy, m the mass, and v the velocity.

The loss of energy is NOT from lift as you suggest. It is from the induced drag caused by lift, and the force is given as D ~ L^2/S with D the drag, L the lift, S the wing area, and the ~ symbol denoting "is proportional to".

[BnZs]

so limit the trust available to the f15 and add some drag then make your case.

And the song remains the same. Identical lift loading and identical thrust loading will result in identical turn performance, all other factors being equal. What part of that is so hard to understand?

[BnZs]

and your lift is acting against the Vel vector to a new Vel vector ...

the force required to change the Vel vector of a heavier object is more than a lighter object.  

therefore the lighter object requires less force to change it's Vel vector.

Which can be a real knotty problem...unless the heavier object also has more force available (lift and thrust) with which to work. Not...all...that...hard...to. ..comprehend.

It can also be a knotty problem if the smaller object has even less of one of these forces in proportion to its weight, say lift...which is why much heavier F6Fs and F4Us can, did, and will easily out-turn the smaller 190s, a fact of history and physics which all your whining and non-science will never change.

[thorsim]

nope slowing down is "acceleration" try again ...

Backing up to the base of this argument.

The original controversy.

Thorism wrote.
While this on the surface is almost a correct statement, it negates a lot of things. Lets begin with a simple no motor , glide only case. You statement seems to imply the heaver object will slow down more quickly. This is not true at all, while correct all things being equal the heaver object will loose more energy, it has more energy stored, and hence the heaver object and lighter object will loose speed at the same rate if the L/D ratio and W/L ratio are the same. And hence if both are gliding would turn on the same downward spiral.

ok but i never said it wouldn't, and that is not my point, i did not deny the effects of any other factors, that was other people exaggerating my point so they could take issue with it.

Now as we add a motor which plane will slow down more quickly will simply depend on the T/W ratio given the above case. I.E. who ever would climb the fastest would slow down the least.

no peoples exaggeration of my statements are misleading, just like you suggesting i was suggesting the flaps were wrong in the quote you posted.

So the problem some of us have with this statement it is a completely miss leading statement.

you should note that any comments directed at B&Z were in response to his made at me.  once again please show where i discounted any of the lift values anywhere in this thread sir.  

since you will be unable to, please address our point of contention which is that i believe that size and weight are factors in and of themselves to be considered in the maneuverability of an aircraft where as others deny that.

BTW HT you, and everyone else for that matter, can feel free to stop misrepresenting my point anytime now.

i do not do it to any of you.

minimum turn radius may have everything to do with stall speed, however not much to do with ACM.

you can call Bob on that steve, if you feel the need.    

t

Bnz wrote.
This statement.
 Is completely accurate, unlike thorsim's.

And now it apears to me Thorsim has a problem because he switches from a debate of physics to a personal attack.

And the persona attack begins, for what reason I can only guess. But BNZ is seems to be trying to describe things as accurately as possible, Thorsim seems to have barly any knowledge of the physics because of statements like this.

Stall speed is a function of Weight/MaxLift  which has everything to do with turn radius.

HiTech

[BnZs]

minimum turn radius may have everything to do with stall speed, however not much to do with ACM.

Nose-to-nose turning (such as in a flat scissors) favors the plane with minimum turning radius. "Bob" seems to think that nose-to-nose turning is important enough in ACM to devote quite a few pages to it.

[thorsim]

right, and that larger aircraft will need to be able to apply all that extra force and have the extra power to over come the energy lost applying that force vs. the other aircraft not burdened with the same weight disadvantage.

does the f4u have the power lift and drag advantages to over come the weight disadvantage it has vs. the spitfire?

i think not.

Which can be a real knotty problem...unless the heavier object also has more force available (lift and thrust) with which to work. Not...all...that...hard...to. ..comprehend.

It can also be a knotty problem if the smaller object has even less of one of these forces in proportion to its weight, say lift...which is why much heavier F6Fs and F4Us can, did, and will easily out-turn the smaller 190s, a fact of history and physics which all your whining and non-science will never change.

[thorsim]

i think there are other factors more important to a scissor and i suspect bob would agree. 

Nose-to-nose turning (such as in a flat scissors) favors the plane with minimum turning radius. "Bob" seems to think that nose-to-nose turning is important enough in ACM to devote quite a few pages to it.

[thorsim]

and it would require a proportionally higher thrust to match the thrust/weight ratio to be able to recover that lost energy as quickly as the lighter aircraft.

theory is all very nice but not always practically applicable ...

as you will notice nobody has tried to use the B-17 example again.  

Pick up a high school physics textbook. Your butchery of the subject is quite comprehensive.

Edit: to be clear, a more massive object also CARRIES more energy than a smaller object for the same velocity. In a turn, a more massive airplane with correspondingly larger wing area will lose the same PROPORTION of energy as a smaller airplane with a correspondingly smaller wing area, everything else the same. Therefore the more massive aircraft will lose the same amount of airspeed as the smaller one as per the kinetic energy equation K = m v^2 with K the kinetic energy, m the mass, and v the velocity.

The loss of energy is NOT from lift as you suggest. It is from the induced drag caused by lift, and the force is given as D ~ L^2/S with D the drag, L the lift, S the wing area, and the ~ symbol denoting "is proportional to".