Flight Dynamic Engine

[RvETito]

While I appreciate the humor I feel the need to say something serious.

 

I don't wanna look like the team and myself personaly, being charged with the helicopter's physical model testing, are blind and deaf for any criticism. Actualy it's fully the opposite. We all will highly appreciate if a regular user finds any flaw in the code. After all this code is written by humans and that presumes mistakes. But I will (and I believe the rest of the team) thoroughly investigate only findings that are clearly described, physicaly argumented and backed up with selfexplaining tracks/screenshots.

 

And I'll give an example straight away- some months ago a user found a bug with the vortex ring state being function of the ground speed instead of the indicated airspeed. It was something that we overlooked during the testing and I and Yo-Yo personaly thanked the user (pardon me but I forgot his nickname) for the good catch. I wish there were more people like him.

 

So keep your eyes open once you understand what's going on in flight and don't hesitate to ask for cunsult or to post anything you find wrong but please provide correct evidence to back up your statement.

 

Thank you.

[Arclight]

Well, now that you mention it, I seem to have noticed an increase in lift when building up lateral speed. I was in near-hover at the time, "funneling" the farp to get the nose in the wind. Obviously I was low to the ground, so ground effect may have played a part in this.

 

Anyway, what occured to me at the time was that lift from the wings may be determined simply by a measure of airspeed, not nescessarily forward speed. :unsure:

 

Gonna have another look at that, and post it in the correct forum if I find anything to substantiate that notion (not very likely, me thinks :D ). :)

Edited July 28, 2009 by Arclight

[old_red_eyes]

To make things feel real he has to design an algorythm'(s) that takes real flight data, and real force models and turn this all into a flight model that Simulates as close as possible, the flight charatistics of the aircraft he's modeling!

 

Into this there also has to be a certain amount of looseness, Or randomness for lack of a better term, to help simulate the real feel! And this is very hard task to do! VERY HARD! I don't think NASA even has it down 100%...LOL Just Kidding!

 

I'm not sure about that. I know what you mean - sometimes a little jiggle is added to simulate "realism". But that is usually because the model is too crude, and leads to a very linear response - which is unrealistic. Frankly, adding randomness is a cop out for the developer who has an inadequate model.

 

If you model down to 2nd and 3rd order effects, then it should not be necessary to add randomness, because the model should contain sufficient characteristics of the real world to achieve realism without a hack.

 

I would be a little disappointed if BS had randomness built in order to achieve it's remarkable realism, and I suspect the devs would be a little miffed if people think the result of their hard work is down to a RNG.

 

It seems that you have never flown real (i.e full size) helis, I wonder if you have any experience writing simulation software?

[m0jo]

Well, now that you mention it, I seem to have noticed an increase in lift when building up lateral speed. I was in near-hover at the time, "funneling" the farp to get the nose in the wind. Obviously I was low to the ground, so ground effect may have played a part in this.

 

Anyway, what occured to me at the time was that lift from the wings may be determined simply by a measure of airspeed, not nescessarily forward speed.

Thats the translational lift created by the main rotor, not the wings. Above a certain speed, the rotor is operating in clean air and this improve performance. On the Ka-50 the most efficient speed is ~130 km/h IAS.

[Yo-Yo]

Speaking of flight dynamics.

 

Anyone tried to hover near a stationary Ka-50? The blades of the stationary Ka-50 do not react to the downdraft from the Ka-50 hovering near by. On the other hand, the blades from the stationary Ka-50 will react to the environmental wind.

 

 

It's not FM. It's a model of how the world reacts with FM trails. We really can model it, but it takes time. A lot of time. So one can choose - Ka-50 today or trails next year... :)

 

 

Frankly, I can say that there were many things we had no time to do - hot air and gas clouds for engines for example. Engines was ready to adopt it and we knew how to do it but the reality was stronger.

[mvsgas]

http://books.google.com/books?id=ewVI57iyLRwC&pg=PT223&lpg=PT223&dq=helicopterflight.net++trim&source=bl&ots=IWfbSOjPKM&sig=cChd1-LuqxgcOv5iYyO8pHi8UL8&hl=en&ei=FlFvSunxBIGRtgeusPDUCA&sa=X&oi=book_result&ct=result&resnum=3

[crazysundog]

Good link, mvsgas!

 

As if I didn't feel dumb enough as it is!!

[LoBiSoMeM]

As you are from Brazil LoBiSoMeM and you like flying low, I got a great video for you :)

You might have seen it before, but this is just amazing :joystick:

 

http://www.patricksaviation.com/videos/Caribougnal/1694/

 

The dream of every helicopter pilot :D

 

Today, low level flight in Rio (my hometown) is only possible in some areas with one of these:

 

http://www.youtube.com/watch?v=0EI7WuvQYcI&feature=related

 

Really sad... :huh:

[Oldflyer2]

Hi All!

 

I as I am in the process of making a good track to try and show what is happening to me in this sim. With my setup and what I seem to be experiencing.

 

I have seen a few posts where Some members have stated the really good control they have! Would it be too much to ask if any member would be willing to post a track of some general flying around a fieled in both Cockpit view and chase view! And if they could also being showing there control inputs? If this is too much to ask that is ok.

 

It sure would be helpfull to see if what I seem to see is what eveyone else sees during a flight! Dang that's a lot of sees...LOL

 

And I do appologize for the ***** languange in one of my posts! it will never happen again! Sorry!

 

Sincerely: OldFlyer2

[GGTharos]

You're probably just not trimming enough, or not using trim properly. This will cause you to fight the autopilot under normal circumstances.

 

Trimming without an FFB stick is not realistic, and does cause some issues and requires you to adjust to it (simply put, the joystick makes trimming without ffb unrealistic, in that you must re-center the stick. In reality the stick will stay where you held it when you trim, as will the pedals. If you look in game, the virtual stick in the pit behaves exactly so).

 

The normal method - from what I hear - is to move the stick a short distance then trim - rinse-lather-repeat. Short means SHORT, not half stick throw.

[mvsgas]

Hi All!

 

I as I am in the process of making a good track to try and show what is happening to me in this sim. With my setup and what I seem to be experiencing.

 

I have seen a few posts where Some members have stated the really good control they have! Would it be too much to ask if any member would be willing to post a track of some general flying around a fieled in both Cockpit view and chase view! And if they could also being showing there control inputs? If this is too much to ask that is ok.

 

It sure would be helpfull to see if what I seem to see is what eveyone else sees during a flight! Dang that's a lot of sees...LOL

 

And I do appologize for the ***** languange in one of my posts! it will never happen again! Sorry!

 

Sincerely: OldFlyer2

 

 

Would it be easier if we just join online somewhere?

We can get a group of guys in Team Speak or ventrilo and see all the flying live.

[SUBS17]

The AP is not supposed to center Yaw, but hold the aircraft in its trimmed position. If you trim it with some sideslip, it will keep the sideslip.

 

 

What about HDG hold surely that should have the YAW centred.

[LoBiSoMeM]

Hi All!

 

I as I am in the process of making a good track to try and show what is happening to me in this sim. With my setup and what I seem to be experiencing.

 

I have seen a few posts where Some members have stated the really good control they have! Would it be too much to ask if any member would be willing to post a track of some general flying around a fieled in both Cockpit view and chase view! And if they could also being showing there control inputs? If this is too much to ask that is ok.

 

It sure would be helpfull to see if what I seem to see is what eveyone else sees during a flight! Dang that's a lot of sees...LOL

 

And I do appologize for the ***** languange in one of my posts! it will never happen again! Sorry!

 

Sincerely: OldFlyer2

 

Ok... I made a track now of a short fun flight boring some brave truck driver and a kind of easy "slalom" over a city. With the control input window on.

 

Just engaged FD, no trim usage at all, no gun slew, no dust protection turned on :thumbup: just "dirty" flying with my cheap, descalibrated and old joy with tiny side throtlle slider as collective and my cheap FreeTrack HT system...

 

As said Cindy Lauper, it's good enough for me! :pilotfly:

 

http://www.easy-share.com/1906986976/FDFlightTest.trk

 

I felt the Ka-50 very "user friendly" with the inputs! Something strange are happening in your system or with your flying style, OldFyer2! I'm flying OK without touch the trim... With trim usage and AP engaged, hands free 90% of the time!

Edited July 29, 2009 by LoBiSoMeM

[bfeld]

I'm not sure about that. I know what you mean - sometimes a little jiggle is added to simulate "realism". But that is usually because the model is too crude, and leads to a very linear response - which is unrealistic. Frankly, adding randomness is a cop out for the developer who has an inadequate model.

 

If you model down to 2nd and 3rd order effects, then it should not be necessary to add randomness, because the model should contain sufficient characteristics of the real world to achieve realism without a hack.

 

I would be a little disappointed if BS had randomness built in order to achieve it's remarkable realism, and I suspect the devs would be a little miffed if people think the result of their hard work is down to a RNG.

 

Now I am not sure if I know what you mean, but anyways, this is a very interesting point :) :

 

Perhaps it feels better to replace randomness by noise. The world is full of (technically speaking: signal-) noise that you will neglect in a pure digital simulation. E.g. if you have a three dimensional box (take a book for a practical example) it has three main axes. Rotation is stable around the axis with the highest mass moment of inertia and the lowest, respectively. The other axis (taking the book again, it's the axis from left to right through the book, when looking at its cover, assuming a standard book format) is instable. Try it, by throwing the book, spinning it around the axes. In the letter case, it will whirl around.

 

Now, instability means, that there is exaxtly one point of stability (around that axis), that you will hardly find in reality, due to noise. In a digital simulation, you will most probably stay within this stable point. So you need to add some sort of noise.

I was told that in the beginning of digital simulators they had real problems with stability. Before that time, they had analogue circuits to solve differential equations that already were subjected to noise.

 

I'm really curious if there's some kind of noise modelled in DCS, in a sense of positive randomness :) .

 

Cheers, bfeld

Edited July 29, 2009 by bfeld

[159th_Viper]

.....I have seen a few posts where Some members have stated the really good control they have! Would it be too much to ask if any member would be willing to post a track of some general flying around a fieled in both Cockpit view and chase view! And if they could also being showing there control inputs? If this is too much to ask that is ok.....

 

 

 

Post #66

 

 

Hi Oldflyer2

I'm 12 years your senior!

If you have not done so, do download Frazer Demo: https://www.digitalcombatsimulator.com/index.php?end_pos=133&scr=products&lang=en

 

Watch what Frazer is doing in the cockpit view, and how the Ka-50 is reacting. You may find it helpful.

[JimMack]

Hi All!

 

I as I am in the process of making a good track to try and show what is happening to me in this sim. With my setup and what I seem to be experiencing.

 

I have seen a few posts where Some members have stated the really good control they have! Would it be too much to ask if any member would be willing to post a track of some general flying around a fieled in both Cockpit view and chase view! And if they could also being showing there control inputs? If this is too much to ask that is ok.

 

It sure would be helpfull to see if what I seem to see is what eveyone else sees during a flight! Dang that's a lot of sees...LOL

 

And I do appologize for the ***** languange in one of my posts! it will never happen again! Sorry!

 

Sincerely: OldFlyer2

 

Here is a video:-

See how small the inputs are of the rudders, collective and cyclic are in the cockpit view

Edited July 29, 2009 by JimMack
more info

[redberon2003]

OldFlyer,

 

 

I've Attached a .Trk File showing a short demonstration of my own flying in the KA-50, I have about 30 hours time in Sim, and about 40 hours of Real time as a Private Pilot in 172's *Which handle nothing like helicopters.

 

For the Seasoned veterans of DCS,

 

 

How was my flying? :joystick:

 

 

:lookaround:

 

:)

forOldflyer.trk

[Frazer]

Watched your track redberon2003 and your flying is stable and controlled. What you could improve is using your instruments more to ensure a coördinated flight.

 

Think of an instructor telling you:

"Turn right here, bank 30, speed 100km/h and climb with 3m/s to altitude 100m. Make sure your drift indicator is centered".

 

Thats what I do to force myself to get the best out of me ;)

[159th_Viper]

Don't be afraid to Push the Envelope - That way you will be comfortable in knowing exactly how far you can push the Whirly-Bird before she Bites!

 

Herewith a track Underflying Railway and Road Bridges at Max IAS (310km/h+)......testament to the Flight Dynamic imbuing sufficient control to successfully navigate the Road Less Taken :)

 

[ATTACH]29459[/ATTACH]

[redberon2003]

Watched your track redberon2003 and your flying is stable and controlled. What you could improve is using your instruments more to ensure a coördinated flight.

 

Think of an instructor telling you:

"Turn right here, bank 30, speed 100km/h and climb with 3m/s to altitude 100m. Make sure your drift indicator is centered".

 

Thats what I do to force myself to get the best out of me ;)

 

 

It's pretty difficult without rudder pedals :cry:, this is something I typically note every few seconds though *I'm a pilot*, out of habbit doing it in the real world. Sadly, the twist on the joystick leaves a lot to be desired.

[mvsgas]

Here is mine.

 

I tried to hover the KA-50 at different altitudes by just trimming and letting go of the controls.

Weather is summer , 25 degrees C, with 3m/s wind at all altitudes

 

Notice I only had 50% fuels and no ammo( :smartass: I know it says on the tittle). I did not see the need to overload the KA-50 nor carry max combat load to test if the trim causes problems. I will upload one tomorrow with max combat load (10800KG IIRC) I you need me to OldFlyer2.

 

Also notice that I tried to trim ad much as I thought required and as long as I kept doing this the KA-50 (IMHO) handle very well and docile.

Almost at the end I tried to show what happens when maneuvering without trimming. Started a very steep left hand turn and by 340 degrees of rotation the KA-50 started to miss behave.

 

I was able to hover the aircraft without auto hover ( just the the normal augmentation channels and altitude control)

 

Now, I know I am a terrible pilot :D:joystick::pilotfly:, I just believe I showed that the KA-50 only misbehaves is you do not pay proper attention to what it is doing, Like I five year old boy :D

[Panzertard]

.... Sadly, the twist on the joystick leaves a lot to be desired.

Sorry, OT - but ... those sticks should have been banned from the market .. heh. Awfull rudder-control ;)

Altough I owned one "gaming flightstick" at a stage, which was okai for a while - the Thrustmaster TopGun - where you could turn it off on the stick, and enable the one in the front of the throttle.

 

Unfortunately - no other vendors picked up this nifty method for "gaming flightsticks" except the one's offering separate units of throttle+stick+pedals.

[Frazer]

Don't be afraid to Push the Envelope - That way you will be comfortable in knowing exactly how far you can push the Whirly-Bird before she Bites!

 

Herewith a track Underflying Railway and Road Bridges at Max IAS (310km/h+)......testament to the Flight Dynamic imbuing sufficient control to successfully navigate the Road Less Taken :)

Ofcourse BS pilots should push the envelope to know the Ka-50's limit but I see too many pilots doing that without being able to fly the shark in a realistic way.

 

It's pretty difficult without rudder pedals :cry:, this is something I typically note every few seconds though *I'm a pilot*, out of habbit doing it in the real world. Sadly, the twist on the joystick leaves a lot to be desired.

It is indeed better to have rudder pedals though it is not impossible to fly precise with a twister.

 

Also notice that I tried to trim ad much as I thought required and as long as I kept doing this the KA-50 (IMHO) handle very well and docile.

Almost at the end I tried to show what happens when maneuvering without trimming. Started a very steep left hand turn and by 340 degrees of rotation the KA-50 started to miss behave.

I personally only use the trim when flying long distances and I want to be able to get my hands off the stick. During aerobatic or combat maneuvering, I cancel all trims. I do this to have the same responses every time again. Since I depend a fair amount on muscle memory.

 

If I have some time, I'll fly a track with precise turns & and aerobatics to cover my statements. :joystick:

[LoBiSoMeM]

I personally only use the trim when flying long distances and I want to be able to get my hands off the stick. During aerobatic or combat maneuvering, I cancel all trims. I do this to have the same responses every time again. Since I depend a fair amount on muscle memory.

 

Me too. But my aerobatic skills are really crap! To do that good, need more discipline and training... I only do simple split-s and loopings...

 

Talking about input devices, I use the pedals of an old steering wheel... works OK. A cheap solution.

 

In really low, fast and direction/speed changing flight, the use of the "stick center and go" trim will be an easy way to kill yourself, I think... The loose springs joy I use is good in this kind of situation: less stress on my arm and more precise control!

 

I saw real pilots talking about the trim feature in real heli, but in the sim, with a non-FF joy, things are different. We need to adjust to our "reallity"!

 

Maybe OldFlyer2 is using too much trim...

[Oldflyer2]

Hello All!

 

Hey! who started this great thread anyway?...LOL Just kidding!

 

I also want too thank those that should me some of there trks. Great flyers in here! Some made me dizzy! but HooA!

 

My thing with any flight model is not only what it allows you to do, but what it should not as well. one thing that I seem to get in my setup is a real hard time getting rid of sideslip!

 

And the heli in slow hover never settles down! it always wants to be turning left or right with no input. so I made this trk and need to ask this.

 

Should I really be able to sideslip this heli at over 260 KPH! I thought that at those speeds the airfoils, wing stabs would give it more wind resistant effect. Make it need to bank more into turns! maybe I'm wrong!.

 

And is there any wild manuveur that would make the coxial rotors touch! I Would think the heli does have it's limits on what you can do! And what you can't!

 

And I really agree on the pedal subject! This sim made me order up some new peddles this week and the track IR system for combat! it looks Awesome!

 

I have waited along time for a great heli sim Since the old days of janes and I am surely hooked on this.

 

I guess I will make this my final thoughts on the whole thing. But I have seen some real honest opions come out here! I hope It all helps. It was not ment at all too hurt.