Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: Benny Moore on February 17, 2007, 09:12:07 PM
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How is the aircraft mass handled in Aces High II? I know from the screenshots in the stall speed thread that lift and drag are intricately modelled, having many points being calculated in real time. Is mass done the same way? If so, is the weight evenly distributed along the points, or is the majority of it in the fuselage and less in the wingtips?
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Mass is distributed as it is in the "real" aircraft, including the mass of fuel and ordie.
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How do you know? And how did they manage it? I've thought about the best way to realistically model mass, and the only thing I could think of was to weigh individual aircraft parts to find their weight and center of balance. It sounds tricky. I'd like to know how Hitech dealt with this.
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Take 2 drop tanks and then drop one. Bet the plane pulls to the side with the tank.
Bronk
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It does. This could be just the drag, but it's probably weighted too. But how is it done? Obviously the drop tanks and bombs are fairly easy to know the weight of, but what about the different parts of the airplanes?
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Originally posted by Benny Moore
It does. This could be just the drag, but it's probably weighted too. But how is it done? Obviously the drop tanks and bombs are fairly easy to know the weight of, but what about the different parts of the airplanes?
In bombers on a B17 if you shut off the #1 engine you will feel some drag and counter it by shuting off the #4 engine
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Manually select which fuel tanks you use using shift+f. I believe you can select right wing tank or left wing tank. See if that has any affect
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You are aware that weight telemetry can be viewed on the E6B?
They probably have a set dry weight CG for an aircraft, and everything expendable that's loaded on the plane affects the CG location proportional to its distance from the "dry" CG.
Everything added to the plane from the hanger affects CG as modeled. Find it hard to believe that anyone with a little AH experience would think otherwise, or need to "test" that.
From what Ive observed, "plane parts" only affect total weight if they had expendable materials on them (loaded pylon, internal fuel tank).
Originally posted by Raptor
Manually select which fuel tanks you use using shift+f. I believe you can select right wing tank or left wing tank. See if that has any affect
Heck yea it does. That's how to best land with a damaged wing. Move the CG over towards the good wing by draining any fuel tanks on the side of the bad wing.
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weight is not mass
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Originally posted by kvuo75
weight is not mass
Since we all live at the surface of the earth where the acceleration of gravity is relatively constant, it has been natural for us to confuse the concepts of mass and weight. To study the difference, we need to separate these two "parameters." We could either leave the earth's gravitational field so that we would have no weight, or create an experimental situation where weight is not a factor. An easy way to do this is to use floating objects. Floating objects still have all their mass, and move almost friction-free in still water, but we don't notice their weight since the water supports (opposes) it. A small block of wood floating in water can be pushed back and forth very easily by hand. Pushing a large motorboat requires either a much greater push or a longer time to have the same effect. The effort required to change the motion of an object is a measure of its mass. The motorboat has a lot more mass than the block of wood.
The metric unit of mass is the kilogram. The kilogram was intended to be the mass of a cube of water one-tenth of a meter on a side. In actual practice the official standard of the kilogram is a cylindrical piece of platinum-iridium alloy kept in a secure location in France. A megagram (metric ton) is the mass of a cubic meter of water. A kilogram is about 2.2 pounds. A metric ton is about 2200 pounds.
The metric unit of weight (or any other force - such as that of a stretched spring, or a bat striking a ball, or a locomotive pulling a train) is called the newton. One newton is defined as the amount of force required to cause one kilogram to accelerate one meter per second every second. A newton is roughly the weight of four ounces, or a pound weighs about four newtons. A kilogram at the earth's surface has a weight of about 9.80 newtons. Above the earth's surface it weighs less and less. Below the earth's surface (in a mine or borehole) it also weighs less. Can you figure out why?
Don't believe a word.
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In engineering terms all weight and mass of an airplane will be measured through the center of gravity and center of pressure that is where all weight is measured and multiplied by the length on the lever arm from said point and the weight acting in that direction from the tip of the lever arm..........Mechanical Engineering Student Ledpig :D
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:O Woh :huh
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Originally posted by squealer
Since we all live at the surface of the earth where the acceleration of gravity is relatively constant, it has been natural for us to confuse the concepts of mass and weight. To study the difference, we need to separate these two "parameters." We could either leave the earth's gravitational field so that we would have no weight, or create an experimental situation where weight is not a factor. An easy way to do this is to use floating objects. Floating objects still have all their mass, and move almost friction-free in still water, but we don't notice their weight since the water supports (opposes) it. A small block of wood floating in water can be pushed back and forth very easily by hand. Pushing a large motorboat requires either a much greater push or a longer time to have the same effect. The effort required to change the motion of an object is a measure of its mass. The motorboat has a lot more mass than the block of wood.
The metric unit of mass is the kilogram. The kilogram was intended to be the mass of a cube of water one-tenth of a meter on a side. In actual practice the official standard of the kilogram is a cylindrical piece of platinum-iridium alloy kept in a secure location in France. A megagram (metric ton) is the mass of a cubic meter of water. A kilogram is about 2.2 pounds. A metric ton is about 2200 pounds.
The metric unit of weight (or any other force - such as that of a stretched spring, or a bat striking a ball, or a locomotive pulling a train) is called the newton. One newton is defined as the amount of force required to cause one kilogram to accelerate one meter per second every second. A newton is roughly the weight of four ounces, or a pound weighs about four newtons. A kilogram at the earth's surface has a weight of about 9.80 newtons. Above the earth's surface it weighs less and less. Below the earth's surface (in a mine or borehole) it also weighs less. Can you figure out why?
Don't believe a word.
That is exactly true this was first proven by Galileo and demonstrated by astronauts on the moon. Objects of differing masses wil be accelerated the same amount by an equal force of gravity. (i.e. a bowling ball wiil hit the ground the same time as a feather without the interference of air resistance.
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Originally posted by Pyro
The moments of inertia are problematic since we only have this data on a few planes and had to use that to make estimates on all the others.
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Originally posted by Pyro
The moments of inertia are problematic since we only have this data on a few planes and had to use that to make estimates on all the others.
I've wondered about the P-38 in particular. If you go into a hard roll and then go to neutral stick the roll stops immediately. Whereas I would suspect that due to the inertia of the 2 engines, turbos, main gear, booms and fuel that it would continue to roll, at least to some degree, until reverse aileron was provided. Maybe not, but a different sim does require some reverse aileron to stop rolling. Just curious.
Best regards.
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That, in fact, was exactly what I had in mind when I asked the original question. I was flying my P-38 and someone asked me what I thought about the inertia modelling. He wondered why the rolling always stopped as soon as you let go of the stick. My initial response was that I thought it's fine, but after thinking about it and trying it out, we discussed it some more. I recall roll inertia being an especially big problem on the P-38 and P-61, because the engines were away from the center of gravity.
Don't get me wrong, I'm not complaining. I think it's very cool that Hitech's modelled the moments of inertia. I was just wondering how they did it, and how complex. It looks like Pyro is aware of the problem, and that due to the lack of data it's unavoidable.
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Mass...
Example, if i was to scoop up all the french peaple and tie them into ball. Then fire them off into orbit they would have a mass and therefore a gravitational attraction. Thus they would attract space particulate and debris, eventually building enough mass to be classed as a moon. Then we could use such a moon (lets call it frenchy) to dump all the nuclear waste and biohazardous materials produced from the earth. A fine contribution for greenpeace made by the french it would be..;)
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Do not get the wrong impression, i love the french.
Well young females anyway. Pretty young ones aged 20 to 30 :aok
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(all rise)
Blessed are those that are here to fly and die with grace and honor in all there virtual glory.
(the response will be - I will)
Do you reject Ho-tards and there inability to gain a 6 shot ---- (i will)
Do you reject Ram-tards, that fly there plane into yours to cause damage, even though the message reads- so and so- collided with you. --- (i will)
Do you reject toolshedders and the grief they cause to furballers when they drop the fighter hangers. ---- ( i will)
Do you reject furballers and the greif they cause to toolshedders for not joining the vulch fest and keeping CAP. ----( i will)
Do you reject tank town, and the spawn campers that live there. - (i will)
Thus ends our Aircraft Mass.
I leave you now in the name of Hitech, Skuzzy, and the HTC crew.
:noid
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When i get my wine and crackers ???:D :lol
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E=MC2 0r MC2=E
So the more energy we have, the more mass is relitive to gravity ?
LOL Slow roll vs Fast roll ? will generation of a magnectic field
occur at high speed ? I should use that Boost more often ! lol
Confussssed :rolleyes
Pass the Crackers Brother : :t
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Go back to school DLfrmHLL..:rofl Or pass pass the lager,l i need one.
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now i need beer, help me..
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i'm getting killed :cry i need help. pass me a lager..
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aaaaaaaaaar/fforgive i've had a drink. i'll regrett this tomorow
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LMAO This Bud is for You
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Originally posted by squealer
the kilogram is a cylindrical piece of platinum-iridium alloy kept in a secure location in France.
A secure location in France??? Squealer's kidding us right?
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*****t i can not bla bla that..........sorry if you know me bla bla ,,,,,,,
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e= ???
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Originally posted by Benny Moore
How is the aircraft mass handled in Aces High II? I know from the screenshots in the stall speed thread that lift and drag are intricately modelled, having many points being calculated in real time. Is mass done the same way? If so, is the weight evenly distributed along the points, or is the majority of it in the fuselage and less in the wingtips?
Actually the calculation is not real time, but uses pre-calcualted tables for the aerodynamics. Real time, high accuracy calculation is not possible on todays computers. From what I understand, what is calcualted are the sum of forces each element of the model give.
As for mass: For every element (wing section, attached bomb, fuel tank etc) you only need 3 things:
Its mass, its inertia moment (per axis) and position. From this you can get the total mass, the center of mass and total inertia moment in each axis.
That, in fact, was exactly what I had in mind when I asked the original question. I was flying my P-38 and someone asked me what I thought about the inertia modelling. He wondered why the rolling always stopped as soon as you let go of the stick. My initial response was that I thought it's fine, but after thinking about it and trying it out, we discussed it some more. I recall roll inertia being an especially big problem on the P-38 and P-61, because the engines were away from the center of gravity.
The problem with inertia was for initiating the roll. P-38 could reach high roll rate but it took time to build, giving a long delay between stick deflection and the actuall roll motion. This seems to be modeled in the game.
When you center the stick there already is a strong roll moment in the opposite direction. This is because the rising wing has now a lower angle of attack (less lift) then the lowered one (while the roll motion is mainteded). It would slow the roll quite fast - how fast? I'm not sure, but in the game (as far as I remember) the "over roll" is negligible. It would be interesting to see how external wing bombs/rockets/DT affect the roll rate and inertia if anyone cares to test this.
Generally, I'm a bit suspecious of the control responses in AH, especially the elevator. I suspect they are too sharp, especially at slow speeds. I don't think that the jink motions we can do near stall are that realistic. Perhaps the stick deflection is linked directly to the wing AoA instead of the elevator's AoA that governs the main wing's. I don't know.
Improving flight models but making them simple and fast enough to run on a home computer is quite a challange I suspect. Some compromises are have to be made and not everything can be modeled directly. A relevant example migh tbe the high speed roll rate. In RL it was limited by the force the pilot's arm could apply on the stick. Our flimsy, plastic joystick can be deflected in a split second. The result is that the actual roll is not directly related to the stick deflection, but slightly delayed. So is the stiffening of the elevator at high speeds.
So far AH gives the best compromise and it keeps improving. We have seen quite a few FM improvements over the last few years. I hope more will come.