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  1. 163277.jpg OK, so its snowing in parts of the UK.  And for a change its actually stuck.  Which means this country is in total Chaos.  I don't know what it is about the UK population and snow that they lose the ability to drive, but that's just the way it is here.  So in response to this embarrassing situation, I'm staying in doors for the duration.

    Which in turn means I either paint my hallway (which isn't going to happen) or i spend the day trying to work out how to accurately calculate all the necessary config values for a Helicopter in ArmA3 without the proper SDK from RTDynamics.

    Love it or hate it the ArmA3 Advanced Flight Model is here to stay.  And once mastered its actually a lot more fun than the basic flight model.  Far more satisfying to prove you have the real skill to fly properly than just fake it?

    Before we go any further lets address the aerodynamic representation of the Cow in the room.  What does it mean?  Why is it relevant?

    The Answer?  It just made me laugh.  Its the inspiration for writing this article simply because the absurdity of the image gels nicely with my feelings toward generating a practical config for the ArmA3 Advanced flight model.

    So for the last year or so I've been banging my head on my desk trying to work it all out and get all my helicopters up and working with it.   This has led to some ...interesting craters on the various A3 Islands.  But hey, its all leading towards progress. 

    I have not failed. I've just found 10,000 ways that won't work.

    rock-efa.jpgI used to be, I'm going to say, a pretty decent Aerospace Engineer back in the day.  But even way back when I did get my hands dirty in CADDS5 and Catia some of the maths related to Aerodynamics scared the crap out of me.  

    This article is not an all out Tutorial.  Not even close.  Lets think of it as the start of discussion.  I'm going to share some things I've found along the way.  If you have a better way to do something, or If I've gotten something wrong.  SHOUT it out and we can all move on and learn together.

    For those that don't know much about the flight dynamics of ArmA3 helicopters, this isn't going to make much sense.  For this that do know something about ArmA3 Helicopters this may make some sense...possibly. 

     

    Step 1 - In your quest to lose hair and go gray early in your life.

    My best advice is find a class of helo; eg: small, med, heavy and modify these the stock values.  There are some values you can calculate and others that require some mysterious and complicated voodoo incorporated into the RTDynamics SDK that we are not privy too.Simulink-Attitude-Hold-Cropped-Wide-e1314192224119.png

    Step 2 - Research, maybe this should come first?

    You will need to find some basic facts about your aircraft.

    • Dimensions,
    • engine specs,
    • mass,
    • rotor blade dimensions. 

    Other values we are simply going to try and make an educated guess.

    Step 3 - The joy of XML

    So we've got our XML file open. You are greeted by a wall of text, figures and variables that  are both terrifying and baffling to all concerned. Some of the variables are easy to explain and find.  Others are a little more esoteric and mysterious.

    xmldoc_1.JPG

    You are going to see long tables of values as shown above with variable names like:

    • SideForceDueToSideslip
    • LiftDueToAoA
    • DragDueToAoA
    • DragDueToSideslip
    • itchingMomentDueToAoA - 
    • YawingMomentDueToSideslip
    • LiftDueToSideslip 

    This is a calculated table of values.  My best advice is find a class of helo, small, med, heavy and use the stock values.  These are calculated by a RotorLib Plugin for MATLAB that on licensees have access to.  Since we don't have all the tools we are guessing.

    BIS has provided a breakdown of the RotorLIB values as well as some of the formulas to create the values on the BIKI but it still isn't the most accessible read.

    https://community.bistudio.com/wiki/Helicopter_Flight_Model_Config_(XML)

    I'm not going to repeat everything in that BIKI article.  I dont see the point.  But some things need de-mystifying...and I don't have all the answers but i am willing to share 

    We are going to focus and the values we can find online or in manuals or calculate from known values. MOM-diagram.JPG

    • Mass - Obvious really. This is the (I believe) empty weight of the helicopter.  I'm basing this off values seen in the Littlebird and KA60 configs etc
    • MomentsOfInertia - Ixx, Iyy, Izz, All these are unique to your helicopter type.  They will change based on the dimensions and mass of the airframe relative to the "allup" Center Of Gravity (CoG)
    • Engines:
      • emergencyPowerHP
      • maxTorque
    • DriveTrains
      • TorqueLimits emergency
      • Load gearRatio Main Rotor
      • Load gearRatio Tail Rotor

     

     

     

     

     

     

     

    I'm in the process of writing an excel spreadsheet to help calculate all the values we are going to need.  But its a long slog

  2. Rock
    Latest Entry

    By Rock,

    NEW VERSION RELEASED
    Admins: NEW server side key!

    V3.111
    - Extended duration upto 5 hrs flight time
    - Ground Control Shelter
    - 3Den Attributes Panel
    - SAR Radar - See diagram
    - Visual and IR Sensor Ranges changed
    - Datalink range to 16km
    http://bit.ly/2VFiGYu #rksl #Arma3

     

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  3. How To Operate a Helicopter Mechanic

     

      A long, long time ago, back in the days of iron men and wooden rotor blades, a ritual began. It takes place when a helicopter pilot approaches a mechanic to report some difficulty with his aircraft.  All mechanics seem to be aware of it, which leads to the conclusion that it's included somewhere in their training, and most are diligent in practicing it.

      New pilots are largely ignorant of the ritual because it's neither included in their training, nor handed down to them by older drivers.  Older drivers feel that the pain of learning everything the hard way was so exquisite, that they shouldn't deny anyone the pleasure.

      There are pilots who refuse to recognize it as a serious professional amenity, no matter how many times they perform it, and are driven to distraction by it. Some take it personally.   They get red in the face, fume and boil, and do foolish dances.   Some try to take it as a joke, but it's always dead serious.   Most pilots find they can't change it, and so accept it and try to practice it with some grace.

      The ritual is accomplished before any work is actually done on the aircraft.   It has four parts, and goes something like this:

    1. The pilot reports the problem. The mechanic says, There's nothing wrong with it."


    2. The pilot repeats the complaint. The mechanic replies, "It's the gauge."
     

    3. The pilot persists, plaintively. The mechanic Maintains, "They're all like that."
     

    4. The pilot, heatedly now, explains the problem carefully, enunciating carefully. The mechanic states, "I can't fix it."

      After the ritual has been played through in it's entirety, serious discussion begins, and the problem is usually solved forthwith.

      Like most rituals, this one has it's roots in antiquity and a basis in experience and common sense.  It started back when mechanics first learned to operate pilots, and still serves a number of purposes.  It's most important function is that it is a good basic diagnostic technique.  Causing the pilot to explain the symptoms of the problem several times in increasing detail not only saves troubleshooting time, but gives the mechanic insight into the pilot's knowledge of how the machine works, and his state of mind.


     

      Every mechanic knows that if the if the last flight was performed at night or in bad weather, some of the problems reported are imagined, some exaggerated, and some are real.  Likewise, a personal problem, especially romantic or financial, but including simple fatigue, affects a pilot's perception of every little rattle and thump.  There are also chronic whiners complainers to be weeded out and dealt with.  While performing the ritual, an unscrupulous mechanic can find out if the pilot can be easily intimidated.  If the driver has an obvious personality disorder like prejudices, pet peeves, tender spots, or other manias, they will stick out like handles, with which he can be steered around.

      There is a proper way to operate a mechanic as well.  Don't confuse "operating" a mechanic with "putting one in his place."  The worst and most often repeated mistake is to try to establish an "I'm the pilot and you're just the mechanic" hierarchy.  Although a lot of mechanics can and do fly recreationally, they give a damn about doing it for a living.  Their satisfaction comes from working on complex and expensive machinery.  As a pilot, you are neither feared nor envied, but merely tolerated, for until they actually train monkeys to fly those things, he needs a pilot to put the parts in motion so he can tell if everything is working properly.  The driver who tries to put a mech in his "place" is headed for a fall.  Sooner or later, he'll try to crank with the blade tied down.  After he has snatched the tailboom around to the cabin door and completely burnt out the engine, he'll see the mech there sporting a funny little smirk.  Helicopter mechanics are indifferent to attempts at discipline or regimentation other than the discipline of their craft.  It's accepted that a good mechanic's personality should contain unpredictable mixtures of irascibility and nonchalance, and should exhibit at least some bizarre behavior.

      The basic operation of a mechanic involves four steps:


    1.  Clean an aircraft.  Get out a hose or bucket, a broom, and some rags, and at some strange time of day, like early morning, or when you would normally take your afternoon nap) start cleaning that bird from top to bottom, inside and out. This is guaranteed to knock even the sourest old wrench off balance.  He'll be suspicious, but he'll be attracted to this strange behavior like a passing motorist to a roadside accident.  He may even join in to make sure you don't break anything.  Before you know it , you'll be talking to each other about the aircraft while you're getting a more intimate knowledge of it.  Maybe while you're mucking out the pilot's station, you'll see how rude it is to leave coffee cups, candy wrappers, cigarette butts, and other trash behind to be cleaned up.
     

    2.  Do a thorough pre-flight.  Most mechanics are willing to admit to themselves that they might make a mistake, and since a lot of his work must be done at night or in a hurry, a good one likes to have his work checked.  Of course he'd rather have another mech do the checking, but a driver is better than nothing. Although they cultivate a deadpan, don't-give-a-damn attitude, mechanics have nightmares about forgetting to torque a nut or leaving tools in inlets and drive shaft tunnels.  A mech will let little gigs slide on a machine that is never pre-flighted, not because they won't be noticed, but because he figures the driver will overlook something big someday, and the whole thing will end up in a smoking pile of rubble anyway.
     

    3.  Don't abuse the machinery.  Mechanics see drivers come and go, so you won't impress one in a thousand with what you can make the aircraft do.  They all know she'll lift more than max gross, and will do a hammerhead with half roll. While the driver is confident that the blades and engine and massive frame members will take it, the mech knows that it's the seals and bearings and rivets deep in the guts of the machine that fail from abuse.  In a driver mechanics aren't looking for fancy expensive clothes, flashy girlfriends, tricky maneuvers, and lots of juicy stories about Viet Nam.  They're looking for one who'll fly the thing so that all the components make their full service life.  They also know that high maintenance costs are a good excuse to keep salaries low.
     

    4.  Do a post-flight inspection.  Nothing feels more deliciously dashing than to end the day by stepping down from the bird and walking off into the sunset while the blade slowly turns down.  It's the stuff that beer commercials are made of.  The trouble is, it leaves the pilot ignorant of how the aircraft has fared after a hard days work, and leaves the wrench doing a slow burn.  The mechanic is an engineer, not a groom, and needs some fresh, first hand information on the aircraft's performance if he is to have it ready to go the next day.  A little end-of-the-day conference also gives you one more chance to get him in the short ribs.  Tell him the thing flew good.  It's been known to make them faint dead away.

      As you can see, operating a helicopter mechanic is simple, but it is not easy. What it boils down to is that if a pilot performs his pilot rituals religiously in no time at all he will find the mechanic operating smoothly.  (I have not attempted to explain how to make friends with a mechanic, for that is not known.) Helicopter pilots and mechanics have a strange relationship.  It's a symbiotic partnership because one's job depends on the other, but it's an adversary situation too, since one's job is to provide the helicopter with loving care, and the other's is to provide wear and tear.  Pilots will probably always regard mechanics as lazy, lecherous, intemperate swine who couldn't make it through flight school, and mechanics will always be convinced that pilots are petulant children with pathological ego problems, a big watch, and a little whatchamacallit.  Both points of view are viciously slanderous, of course, and only partly true.




    by William C. Dykes
    Jolly Green

     

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    Recent Entries

    Ok now this is bugging the hell out of me.

    As a content creator I am protective over my own creations.  I spent thousands of hours making addons for free.  The least I should get is credit and respect yeah?  I feel strongly about the rights of other creators too.  Whether they are individuals, groups or corporations.  You make the effort, put in the hours you should get the rewards?  Whatever they are.  Sounds fair doesn't it?

    Have a read of this:  

    All things arma.PNG

    All Things ArmA III was one of my favourite Facebook ArmA groups.  I say was because reading Mr Jason Mulligan’s (the Page Admin) post just pissed me off.  He perfectly identifies himself as the typical selfish user.  He’s perfectly happy to take content no matter where is comes from.  F@%$ the hidden cost to the end user.  He’s an admin on one of the bigger ArmA Fan pages on facebook and look at his attitude.

     

    So what is the hidden cost?

    Content creators see this attitude and say “Why the hell am I bothering to release content when I get treated like this?"  (Its certainly how I feel.  I’m actually sorry I came back to the ArmA Community.)

    So what happens when genuine creators feel unappreciated, used and abused?  

    • They go underground and stop releasing Public content.
    • The only people left in the community are the end users and the thieves.
    • The knowledge base that was held by the older and wider community starts to vanish.
    • The people with all the knowledge don't bother posting and helping anymore.
    • The community standard goes down hill rapidly.
    • This leaves only the people willing to steal content.

    See where this is going?  If you are truly a fan of the ArmA series and the ArmA Community, you shouldn't tolerate theives.  You should support the decent addons creators.  They are the ones that make the mods you play with all the time.

    Without them, your experience is really going to change.

    Think about it.

    Rock

     

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