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jammydodger

What sort of physics do you want for the heli's?

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I like the idea of the copilot taking over "you have control!" smile_o.gif

Thing with BF Vietnam is that they've pretty much replicated real helicopter physics. You'll be surprised to know how cose they are from real choppers (it also seems to me that they've dumbed it down a bit in BF2).

The important thing to me would be making Helos realistic enough so people won't use them as mad UFOs in multiplayer games. If they are too easy to fly they would kill the gameplay balance. At least you want to know that the guy behind the controsl has to have some skills...

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Should have been a poll imo, i vote 1 for realistic because being more realistic is usually a good thing, same for tanks, i want brakes, throttle and gears, it wont make the game alot more dificult but will definetly make it alot more fun and interesting smile_o.gif .

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Quote[/b] ]I'd love to see the "eject" option totally REMOVED. If something goes wrong, you shouldn't have the option of magically ejecting through the rotor blades. You ride it in and hope for the best.

this is already standard in WGL5, the Franzeunit AH-64 pack, etc.

Quote[/b] ]Could also be interesting if there was some way you could fly from the co-pilot seat (in the helos where this makes sense)

apparently the Our Weapons russian mod team was able to accomplish this with their new Mi-8 pack. i haven't tried it out myself yet, though.

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I like the way the helicopters are controlled, not to hard, but not to easy either. They could indeed remove the eject, however giving in account that you can survive a helicopter crash. Normally the blades would start to turn around from the falling of the chopper, so when it hits the ground, he isn't going to fast(can even land undamaged from time to time and That's what I learned, correct me if wrong)

they could make the choppers more complicated, for example all the buttons etc like in chopper sims, this could add to the gameplay==> less pilots, so people with skill fly, and not noobs who fall to the ground after a minute because they are goinging to fast...

But then they should do that to every vehicle, to much work/complicated, and not all people would like that because of the complexity. This would be in real life, so when you capture a tank, you don't know how to control it, so you cannot use it, or you have to learn it.

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The 1 problem I see with having the Heli's that need a skilled pilot to fly them is that when you get noobs and people who haven't got the skills to fly them they will be just crashing them all the time, and leave the other people who can fly them very annoyed that they keep wasting the Helli's.

It would be good if there was a type of training session for the heli's & planes and until you pass a test in them you are unable to fly them online.

Cheers

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The 1 problem I see with having the Heli's that need a skilled pilot to fly them is that when you get noobs and people who haven't got the skills to fly them they will be just crashing them all the time, and leave the other people who can fly them very annoyed that they keep wasting the Helli's.

If BIS changes it to a more realistic way we will all be nubs and screw up when Arma comes out biggrin_o.gif .

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You always have to go through a learn-proces. Some games are easy, some are hard, some give different styles of playing, all up to the gamer to decide and select the best. So finding decent pilots at the beginning will be hard, but adding trainings of how to fly, could indeed be nice. Then we would also be very close to a real war-sim. But it stays a game...

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I think the current level of realism vs useability in OFP's choppers is very good. Removing the automatic raise and lower over terain -leaving that down to the player would be better, as would removing the eject when pissed off with flying would be too!

I enjoy flying choppers in OFP and the fact that I can do it with my trackball mouse and keyboard makes it much more user friendly even if not totally realistic. Bear in mind that doing anything on a PC is often harder than in real life due to your lack of peripheral vision and many other cues such as rolling sensations, swinging sensations and vibrations etc.

When the day comes that we all have total all round vision pc monitors with full force feedback pitch and roll chairs and proper simulator controls, that will be the day to go for full simulation!  biggrin_o.gif

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Removing the automatic raise and lower over terain -leaving that down to the player would be better,

The auto raise/lower is already turned off automaticaly when you use a Joystick smile_o.gif

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Hmm! So it is! So there ya go, BIS had even thought of that! huh.gif So that just leaves this ejecting thing. But hang on what is the real problem with this?

In real life, if the moment took you, I can't see what could stop someone from abandoning the controls, reaching for an emergency shoot and bailing out the doors! Certainly could be usefull if the chopper had caught fire! Just be sure not to deploy your shoot untill clear of the rotors! wow_o.gif

I think I'm quite happy for BIS to leave chopper realism as it is for ARMA!  biggrin_o.gif

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So that just leaves this ejecting thing. But hang on what is the real problem with this?

In real life, if the moment took you, I can't see what could stop someone from abandoning the controls, reaching for an emergency shoot and bailing out the doors! Certainly could be usefull if the chopper had caught fire! Just be sure not to deploy your shoot untill clear of the rotors! wow_o.gif

Ejecting from most helicopters just isn't an option at all. That's one of the primary things that makes helo pilots a different breed than fixed-wing aviators. They know that no matter what happens, they don't have an option to bail. It's auto-rotate or nothing.

And with the realistic feel of OFP, it just doesn't really fit. I've even had a few times where I did eject from a chopper in the game, but then felt like that was so absurd that it kind or ruined my gaming session, so I started over. HaHa tounge2.gif

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Removing the automatic raise and lower over terain -leaving that down to the player would be better,

The auto raise/lower is already turned off automaticaly when you use a Joystick smile_o.gif

Nah, it's still auto NAP. Unless that was added in the very latest patch.

Edit: the collective or rotor rpm is just a little less terrain automated with joystick, not completely as it should be

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Tell you what would be really entertaining also:

- dissymetical lift (that right Jinef?)

You get more lift from ground closer to the rotor than farther away. So Hovering low over sloped terrain, funky stuff happens. That's what would make flying OFP helis much more enjoyable and provide a higher learning curve.

You know me, I love insanely high learning curves, but their slopes don't need to be too steep as one can enable / disable options.

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*reads Bn's post ....*

*rolls eyes ... shakes head*

Ok here we go, I wrote this with assistance from another helicopter pilot quite a while ago.

Quote[/b] ]

This text outlines the flight model limitations in Operation Flashpoint: Resistance 1.96.

Contents:

1. Introduction

2. Flight Controls

3. General Factors Affecting Flight

4. Features of Rotary Flight

5. The OFP flight model in comparison.

6. Game play Considerations

1. Introduction

The intent of this study is to outline the limitations of the OFP flight model in order to be able to offer solid foundations for improvements in the future flight

model of a BIS game engine. I am going to begin by outlining the fundamental flight controls in helicopters and look at what is needed to fly a helicopter in terms of input. I will then go through several factors that

affect the handling/flight characteristics of a helicopter that are not modeled in the current simulation. I will then look at several features of rotary flight that are interesting and add

the extra little bit of challenge to flying helicopters. I will then surmise this all and look at how OFP represents it, areas to improve etc. Finally I will look at possible ways of putting this into a game environment and making an accessible flight model for teenage gamers.

2. Flight Controls

The 3 main controls for rotary flight are:

Cyclic

Collective + Throttle

Anti-Torque Pedals

Cyclic:

The cyclic stick controls the direction in which the helicopter moves, it does this by tilting from the central pivot the entire rotor assembly (referred to as the rotor disc) so that each blade's pitch changes once per cycle, hence the name, in the direction the stick is moved.

In summary the cyclic controls the helicopter's pitch and bank attitude. Some helicopters augment cyclic pitch inputs with control surface inputs from other sources, e.g. the fly-by-wire tail plane on the Blackhawk and B214ST.

Collective:

The collective is a helicopter's primary altitude control. It varies the lift produced by the rotor disc by increasing or decreasing the pitch of all the main rotor blades collectively, hence the name of the control.

Throttle:

On the collective stick you usually find the throttle, which controls the power of the engine(s), this is a separate control. However, all modern helicopters have governor or computer controlled engines,

which maintains a roughly constant RPM except in autorotation regardless of the pilot inputs.

Anti-Torque Pedals:

The anti-torque pedals compensate for the torque produced by the main rotor by increasing or decreasing the pitch of the tail rotor blades.

The anti-torque pedals have most effect when stationary, in forward flight they have less effect on the helicopters heading and are primarily used to keep the aircraft in trim. Tandem-rotor and coaxial-rotor aircraft use the opposing torques of the 2 main rotors to provide directional and balance control, often assisted by large vertical control surfaces (fins and rudders). As in conventional helicopters, these control functions are maintained through movement of foot pedals.

Example of flying the helicopter and coordinating the controls:

In order to actually get the helicopter flying you need to coordinate all these controls. So let's describe the controls in a takeoff, short forward flight and then a hover for a helicopter with a counter clockwise rotor system.

1: On ground, engines running, rotors at 100% rpm.

2: Lift collective slowly, pitch increases thus torque increases.

3: The aircraft lifts off ground, you need to add left pedal to keep it on heading.

4: You add forward cyclic, the attitude lowers and you need more collective to keep airborne.

5: More collective = left pedal.

6: You fly forward into un-disturbed air; the rotor disc becomes more efficient.

7: You lower collective to keep your desired altitude, no left pedal, maybe some right pedal.

8: You flare to a hover. The nose rises and you need to lower collective to keep desire altitude, pedal to the right.

9: As the aircraft loses translational lift you need to raise the collective to maintain altitude, increase throttle to maintain RRPM and apply pedal to maintain heading.

This may seem overly complex however it becomes second nature.

3. General Factors Affecting Flight

In Vietnam out of the 7000 helicopters downed 4500 or so were due to crashing. Mountainous terrain, hot rising air so low air density, often overloaded and very hard to navigate = Horrible place for helicopters.

Environment

Climate

Weather

Weight

Drag

Malfunctions

Environment:

> The terrain dictates the helicopter's flight, high altitudes have a lower density of air so the rotors provide less lift and engines operate less effectively.

> When landing and taking off in sand or snow the rotor wash can kick up stuff to cause 'brownouts' or 'whiteouts'.

Climate

> Arid climates offer problems for helicopters, dust/sand kicked up the downwash of rotors is damaging to the airframe, can damage the engines significantly and can cause erosion of the rotors leading to cracks and faults.

> Cold climates offer problems for helicopters; icing in flight causes dangerous unbalancing and extra weight.

Weather

> Wind - Helicopters land, takeoff and hover into the wind. The only thing a helicopter pilot doesn't do into the wind is urinate.

> Temperature - Efficiency of the rotors depends on air, cold air = thick hot air = thin.

Weight

> Fuel - The amount of fuel an aircraft carries determines its weight and operating capabilities.

> Cargo - The amount of cargo an aircraft carries determines its weight and thus performance.

Drag

> The addition of an under slung load, the attachment of an optional external piece of equipment (e.g. hoist/winch) or even having a door open will add significantly to drag, requiring more collective pitch and larger forward-cyclic-pitch inputs.

Malfunctions

> A lot of things can go wrong in a helicopter, triply so if bullets happen to be entering important systems and severing important cables. A helicopter pilot needs to be able to diagnose and react quickly to a certain failure.

4. Features of Rotary Flight

Ground effect: Ground effect is a condition of improved performance encountered when operating near (within 1/2 rotor diameter/ 2/3 in UK...) of the ground. It is due to the interference of the surface with the airflow pattern of the rotor system leading to a reduction in induced flow, and it is more pronounced the nearer the ground is approached. Ground cushion is reduced by hovering over uneven ground, hovering in a strong wind (although the effect here is minimized because the wind will probably induce translational lift) or hovering close to a building or other object that causes air to recirculate back into the disc from the top.

Translational Lift: As the helicopter translates into directional flight from a hover, the rotor disc leaves turbulence and vortexes behind making the system more efficient producing more lift.

Into the wind: All helicopters will try to "weathercock" into wind at low speed. Hovering downwind affects controllability: the wind will catch on the upper surface of the tail plane, pushing it down. Hot turbine exhaust air will be blown back to the intake, raising the temperature of the air going into the engines and reducing their efficiency. Some helicopters have unusual characteristics whereby certain crosswind components are actually more or less advantageous. E.g. Chinook hovers best (i.e. uses least power) with a crosswind from the 9-10 o'clock, while Lynx Mk 1 and especially early Huey (up to B205A, or late-model UH1H) suffered poor performance with crosswinds from the 2-5 o'clock directions owing to their poor tail-rotor design

Dissymmetry of lift: The imbalance of lift caused by the differences in lift from the retreating blade and the advancing blade. Constant cyclic correction is needed.

Retreating Blade Stall: A tendency for the retreating blade to stall in forward flight is inherent in all present-day helicopters and is a major factor in limiting their forward speed. Just as the stall of an airplane wing limits the low speed possibilities of the airplane, the stall of a rotor blade limits the high-speed potential of a helicopter. The airspeed of the retreating blade (the blade moving away from the direction of flight) slows down as forward speed increases. The retreating blade must, however, produce an amount of lift equal to that of the advancing blade. Therefore, as the airspeed of the retreating blade decreases with forward aircraft speed, the blade angle of attack must be increased to equalize lift throughout the rotor disk area. As this angle increase is continued, the blade will stall at some high forward speed.

Vortex Ring State: A massive descent-rate in excess of 3000 feet/min when fully developed, accompanied by random pitch and roll. VERY nasty!! Conditions conducive to vortex ring state are a vertical or nearly vertical descent of at least 300 feet per minute and low forward airspeed. The rotor system must also be using some of the available engine power (from 20 to 100 percent) with insufficient power available to retard the sink rate. These conditions can occur, during extended operations in the high hover with an un-noticed sink-rate, approaches with a tailwind or during formation approaches when some aircraft are flying in turbulence from other aircraft.

Autorotation: During powered flight, the rotor drag is overcome with engine power. When the engine fails, or is deliberately disengaged from the rotor system, some other force must be used to sustain rotor RPM so controlled flight can be continued to the ground. Adjusting the collective pitch to allow a controlled descent generates this force. Airflow during helicopter descent provides the energy to overcome blade drag and turn the rotor. When the helicopter is descending in this manner, it is said to be in a state of autorotation. The helicopter has potential energy by virtue of its altitude. As altitude decreases, potential energy is converted to kinetic energy and stored in the turning rotor. The pilot uses this kinetic energy to cushion the touchdown when near the ground.

In-flow roll and tail-rotor roll: Minor effects noted only during hover and transition to/from forward flight. Can be disregarded for BIS simulation purposes; if you were going to produce older, imbalanced helicopter models you might consider including these, but frankly I wouldn't bother.

5. The OFP flight model in comparison.

The OFP flight model has several features that offer playability to some and a pain the backside to others.

Feature 1: Coupling of Anti-Torque and lateral cyclic.

This is nice for tour guide flights where a helicopter simply has to go up, straight, turn around and down. However military flying, especially gunship, requires added capability to quickly acquire targets, make hard turns, do evasive maneuvers etc.

There is a sort of anti gravity device on OFP helicopters, when they descend to the ground there is a massively exaggerated ground effect which produces a lot of lift. It is so strong it is almost like a terrain avoidance system. Ground effect should be modeled in a more plausible way.

OFP helicopters are immensely stable, you can hover one and then go to dinner, watch some TV, go to sleep and in the morning they will be in the exact same position with only 10 % fuel used.

The engines are Herculean and impervious to over torque, you can climb from 0 to 3000 feet in less than a minute without any reluctances.

OFP helicopters also seem to have a barrel of nitro glycerin aboard each one, even the most gentle auto-rotations (A gentle autorotation is hitting the ground traveling forward at 30 Mph) can cause the helicopter to explode spectacularly. This is to do with collision detection and airframe armor values however it is an important part of crash landing and walking away from it (Something that should be most definitely modeled, helicopters currently are either are alive or dead, same for their occupants.)

Rotor-Blades are solid, the collision detection should obviously represent this.

Sound modeling of helicopters is too simple. You can be 100 meters from a full troop transport and not hear it if it’s behind a ridge. This applies to everything however helicopters are particularly vulnerable as you can hear them from 5kms away.

6. Game play Considerations

A lot of people are going to be annoyed if they cannot fly the ‘choppers’ so a cadet mode is the most obvious answer to this. People who want to use all vehicles for fun games in MP can play on a server where the cadet system is enabled.

If the flight model is more accessible to people who would like to make modifications towards realism the next generation of OFP will attract the serious helicopter simmers and helicopter pilots looking for training.

I hope this has given a clear objective to aim for, or at least guidance in how to improve the older flight model.

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Bloody hell, just because I don't know all the l33t terminology. mad_o.giftounge2.gif

I mean dissymetrical lift, from sloped terrain then. yay.gifyay.gif

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Removing the automatic raise and lower over terain -leaving that down to the player would be better,

The auto raise/lower is already turned off automaticaly when you use a Joystick smile_o.gif

Nah, it's still auto NAP.  Unless that was added in the very latest patch.

Edit: the collective or rotor rpm is just a little less terrain automated with joystick, not completely as it should be

It's completely off, honest. Are you using the joystick just for the cyclic, or also for the collective? That might be it... I use a separatte throttle stick and it works for me. Full control goodness smile_o.gif

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Ejecting from most helicopters just isn't an option at all... they don't have an option to bail. It's auto-rotate or nothing.

True. And that will help people to use the Helis in a more realistic way. None of that "fly over enemy base and jump" business.

Did you know that auto-rotations are also implemented in OFP? They are hard to master, but they do work. I'm not sure most people is aware of the complexities of the current helicopter physics when using a joystick... You'll miss all this if you just fly with the mouse.

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Well terrain following is not comlpetely off with a joystick. I do have a seperate throttle as well, last I tried there was a hell of a lot of terrain following... I don't know what version of the OFP exe you got. tounge2.gif

Yes autorotation is in OFP, but it's not necessairly accurate either. Actually it is quite bad without a joystick especially (not sure with one) as when you control the collective it automatically stalls the blades as that is connected to the engine RPM somehow, it's like you can't feather the rotor.

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Ejecting from most helicopters just isn't an option at all... they don't have an option to bail. It's auto-rotate or nothing.

True. And that will help people to use the Helis in a more realistic way. None of that "fly over enemy base and jump" business.

Did you know that auto-rotations are also implemented in OFP? They are hard to master, but they do work. I'm not sure most people is aware of the complexities of the current helicopter physics when using a joystick... You'll miss all this if you just fly with the mouse.

True on ejection, however this is fairly easily fixed in mods or addons. Check WGL for example.

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Ah, the helo controls thread! I guess this is the place for my question: In most computer games, helicopters seem to be flying with their nose pointing downwards (during forward flight) to a greater or lesser degree. Is that realistic?

I know that real-life helicopters can pitch their nose down for quicker acceleration, but do they do that (albeit to a lesser degree) during conventional forward flight? I've never flown in a helicopter myself, but from TV pictures they seem to fly pretty much straight ahead.

Expert advice would be greatly appreciated.

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In most computer games, helicopters seem to be flying with their nose pointing downwards (during forward flight) to a greater or lesser degree. Is that realistic?

I know that real-life helicopters can pitch their nose down for quicker acceleration, but do they do that (albeit to a lesser degree) during conventional forward flight? I've never flown in a helicopter myself, but from TV pictures they seem to fly pretty much straight ahead.

Expert advice would be greatly appreciated.

If a chopper did not put its nose down it could not fly forwards, it would simply hover. In order for it to move in any direction it would have to tilt its rotors into the direction it wanted to go. The main rotors don't just supply the lift but also the directional force. This can only be aceived by tilting. The faster you want to go the more tilt you would need.

I'm sure there are plenty of 'tech heads' in here who will give you the same blurb by using words like 'cyclic controls' and 'collective lift', but it all boils down to the same thing in the end - no tilt no move! wink_o.gif

Btw, that video clip was a bit scarry! Bet the pilot had a wet moment as he chopped his tube in half! rofl.gif

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Well, to whatever degree 'terrain following' is simulated on keyboard vs controller, the simple fact is that ground effect is

way too strong in OFP.

The 'attitude' of the helicopter is how the airframe is positioned in the air, with forward tilt or backwards tilt etc.

The direction of the helicopter's movement is controlled by the movement of the entire rotor disc. This is done with the cyclic, which usually controls hydraulics.

When in the hover the helicopter can move in any direction without the attitude of the helicopter changing. Meaning that the helicopter is straight and level but the rotor is tilted forward. As the rotors tilt forward and the speed is increased the airflow causes the attitude of the airframe to lower.

Is this the tech-head stuff you wanted?

Summary: Wait and see what BIS sticks in ArmA and then start the wishlists for OFP2.

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Well, to whatever degree 'terrain following' is simulated on keyboard vs controller, the simple fact is that ground effect is

way too strong in OFP.

Ground effect is where the chopper would experience increased lift close to the ground as it came to rest on it's own air cushion! If you hover steady and slowly decrease the collective untill you start to decend slowly, you should continue to decend slowly untill about 10feet or so from the ground after which you would come to rest on your air cushion and hover untill you ruduced some more collective.

This does not happen in OFP so I would have to assume that there is NO ground effect in OFP not too much.  icon_rolleyes.gif

Regarding the terrain following feature, I find that it is only pressent when I use the keyboard controlls. The minute I touch my Cyborge 3D Gold joystic the feature switches off and I have to make sure that I increase collective manually as I approach elevated terrain or else - Wham!  biggrin_o.gif

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