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Flight Model Again V2


Focha

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Which could indicate that the Huey also isn't perfect, doesn't necessarily prove that the Gazelle is correct. Surely someone's feedback based on real experience is worth listening to? We all stand to benefit if we can get to the bottom of what's going on with the flight model.

 

Oh I listen very carefully. Sometimes it seems to me that a part of the community thinks that the military pilots (working with the developers) are not worth to be heard.

 

Since everybody can have an own opinion here is mine: I will put more faith into the developers word that several actual Gazelle pilots affirmed a large part of the FM than to thrust one or two persons (who are unknown to me) saying they are RL pilots (which I cant check) flying helicopters of different types. And please don't tell me that everything from Airbus helicopters flies the same way. Even the BK117 and the C2 version (EC145) show some different behaviour. :smilewink:


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Once you start to exceed 70 or 80 Km/h the massive tail fin surface area plus tail boom directional fins start to take authority on directional flight. One of the fenestron design strengths comes from its ability to reduce tail rotor engine drain to almost nought in forward flight, this leaves all power for the main rotors.

 

 

Any fenestron design you look at has a massive tail fin surface area and this is simply a benefit of an aerodynamic tail rotor!

 

 

You are simply fighting a very strong wind vain once a certain speed is achieved!

 

 

Thank you Rogue Trooper for your explanation. I never flew a helicopter, but i think the hard stop of the tail could be a much more smooth. Maybe the FM could need a little bit of finetuning in this sectioon. Just a feeling. Fly straight above 90 km/h and hit the Rudder full left and then full right. First the tail will turn right ...smashing against a invisible wall...


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Don't tell lies.

 

I don't have to… look at my file.

 

Could you explain to me why your FuelFlow went to 0,0 3 seconds before you hit the ground?

 

 

Edit: Before you complain the file is too old, here is a fresh one from 5 minutes ago. Quick and dirty but sums it up. Recovery in less than 20ft after adding full collective. I don't think we need to continue to compare the FM's. Neither of us will be happy and some people will loose their believe in the UH-1.

TacviewHueyreccover.zip

Tacview-20180707-122909-DCS.zip


Edited by FSKRipper

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See I know what you're doing in such a descent. Tell me, do you let the rotor overspeed? (ps. I already know the answer because of the RoD).

 

 

And fyi, look back, I never said the huey FM was perfect. I quite clearly stated the opposite. But not loading the blades and let the rotor overspeed is outside any normal flight parameter anyway and it avoids vrs as a whole because you have to load the disk to just be able to get into vrs. And yes apparently you can get out of such a descent that way and it clearly shows another mistake in the FM.

 

 

You can test the mistakes in the huey FM in much simpler ways. Just be glad the gazelle doesn't simulate ground resonance (that I know off).

 

The gazelle can't get into vrs. Telling me it can't be done irl is bullshit because the helicopter still adheares to the same rules of physics, unless you say it's french, you might have a point there, they're quite special.

 

 

But if you load the helicopter in a 6000ft/min RoD straight(ish) down and you load it just a little bit. The disk simply stalls out. I don't know the exact RoD needed in the gazelle irl but I'm quite sure why the advisors to poly say they have never encountered vrs is because they're trained to avoid that whole situation in any case.

 

 

But if you don't believe me on the VRS. I suggest you take the word of mr Wagtendonk. He has a book called 'Principles of Helicopter Flight' it's an interesting read and it's mandatory for all my students because it's so much better then the other books publically available that I know off.

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@borchi Thank you for that detailed post! Now my interest in the Gazelle's flight mechanics has really been piqued :) So this is out of pure curiosity and by means meant as ''i can't believe thats how she acts in real life''. What i have noticed when flying with AP/Gyro (and thus SAS) on or off is the following;

 

With AP/Gyro on, she always returns to level flight (or trim settings) when rolling/pitching once you let go of the stick, with a tendency to climb once back in level flight (unless you have her trimmed to bank or decend). This makes sense to me since the SAS is intended to ease and increase transitory flight savety. Give the pilots a bit of slack while on route. I take it, that the SAS operates via actuators that constantantly adjust the swashplate to maintain that level flight or altitude/speed hold if you additionally engage that. So far, so good.

 

Coming back the observation in the OP, when you disable the AP (disengaging the gyro did not make any difference according to my obersation in game) the SAS is disengaged also and thus the Gazelle does not show the automatic stabilization to level flight that i described above.

 

What i see happening is the following. With AP disengaged, when you put her into a bank, the Gazelle holds that bank angle but starts to slowly pitch down, which needs to actively countered by adding pitch. Same as in fixed wing aircraft, which is to be expected.

 

Now, with AP still off (thus trim not functioning), straight and level flight and no bank at all, the Gazelle can fly perfectly straight ahead for an extensive period, without any cyclic corrections needed by the pilot. I have tried that for various speeds. For instance, i can increase collective so that she reaches 210kmh, keeps that speed, and flys perfectly level (no ascend/descend whatsoever) for a really long time. All by minute joystick inputs before i finally let go of throttle and stick. I actually increased the game speed to see how long she can fly like that.

 

QUESTION: assuming this is intended and correct behaviour, is this due to its rotor and aerodynamic design (streamlined fuselage and big tail section etc.), OR do those actuators (also used by the AP and SAS) still operate and constantly correct the swashplate albeit with differing flightpath behaviour than with AP/SAS engaged?

 

 

BTW; the MI-8 has an auto-pilot described in detail in the manual on page 215-223. I am not really proficient or knowledgeable about hte MI-8, but i have disabled that system mid flight, and you pretty much instantly loose control if you don't actively steer via cyclic. The MI-8 instantly starts pitching up, eventually stalling pointing up into the sky :) But it really is a totally different design, big and heavy, way more blades, no big tail section etc.

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If you compare the tail fin of a Huey or the hind.....

 

You said Hind...What? :)

Control is an illusion which usually shatters at the least expected moment.

Gazelle Mini-gun version is endorphins with rotors. See above.

 

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See I know what you're doing in such a descent. Tell me, do you let the rotor overspeed? (ps. I already know the answer because of the RoD).

 

 

And fyi, look back, I never said the huey FM was perfect. I quite clearly stated the opposite. But not loading the blades and let the rotor overspeed is outside any normal flight parameter anyway and it avoids vrs as a whole because you have to load the disk to just be able to get into vrs. And yes apparently you can get out of such a descent that way and it clearly shows another mistake in the FM.

 

 

You can test the mistakes in the huey FM in much simpler ways. Just be glad the gazelle doesn't simulate ground resonance (that I know off).

 

The gazelle can't get into vrs. Telling me it can't be done irl is bullshit because the helicopter still adheares to the same rules of physics, unless you say it's french, you might have a point there, they're quite special.

 

 

But if you load the helicopter in a 6000ft/min RoD straight(ish) down and you load it just a little bit. The disk simply stalls out. I don't know the exact RoD needed in the gazelle irl but I'm quite sure why the advisors to poly say they have never encountered vrs is because they're trained to avoid that whole situation in any case.

 

 

But if you don't believe me on the VRS. I suggest you take the word of mr Wagtendonk. He has a book called 'Principles of Helicopter Flight' it's an interesting read and it's mandatory for all my students because it's so much better then the other books publically available that I know off.

 

Never said everything is fine but I'm a bit tired of the same discussions every 4 months. Some posts ago you said I'm lying, know you admit this UH-1 error. Even with a VS of 980m/s (same as your VS) I'm able to do this recovery :huh:

I own the book btw. but as a RL pilot you should know that sometimes there are some big deviations from the standards according to the specific aircraft.

 

Sorry, regarding VRS look at post 16, it was never said it's impossible! Regarding your RL experience I would like to point you to my post 26. I don't know your background but I know some civilian spare time pilots knowing not more about aerodynamics and mechanics as my son. This is another reason why I put more thrust in military experience since in most countries the pilots are expected to earn a degree in one of this areas. In other countries they are better taxi drivers and driving a car doesn't mean understanding how it works. Look at the streets...

 

So for me this discussion ends here, much fun furthermore… :thumbup:


Edited by FSKRipper

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Ok so also a real helicopter pilot here, 2050 hours flight time. 21 hours in an Astar. The op has some valid points. I'd like to see VRS implemented as well. But when playing with a joystick that has a very weak or no centering spring it "feels" a lot like the astar did to me. Are the stick positions exactly correlated to where they would be in a real aircraft? Probably not. But allowances must be made for this being a video game. It took me 10 hours to learn to hover a real helicopter and 24 to solo. Imagine how many people would rage quit if it took that much time before being able to use the module at all. One other thing I'd like to see implemented is a little more translating tendency and right skid hanging low, But overall I think its a great module and I reccomend it.

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''One other thing I'd like to see implemented is a little more translating tendency and right skid hanging low''

 

But thats the issue. You say you would like to see this implemented. And i gather you say that because of your background in RL helicopter aviation, with different helos. But how do you know that the Gazelle does have this more pronounced than we see in the DCS module? Isn't this the point of DCS; to simulate specific aircraft as close to RL as the developers can possibly make them?

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You know I could be wrong about the translating tendency. Maybe the gyros are taking care of it. But if that's the case the right skid should be hanging lower than the left. But I don't complain about it. I just mention it as an observation because I have time in a similar but not identical aircraft. And yes I'd like it to be as realistic as possible but if was 100% realistic non-helicopter pilots wouldn't be able to fly it.

Full disclosure I consider one of the Devs a friend, however I won't hesitate to tell him or anyone else the areas I feel could be improved. And that friendship actually grew out of me contacting him to let him know what I thought was right and what needed work and he took my concerns to the actual gazelle pilots. Could it be more realistic? Sure. But I think its pretty damn good and feels more real to me than the Huey does, of which I've done a lot of work in in real life. But hey thats my opinion take it or leave it.

 

And to the guy who said the tail rotor isn't realistic at speed... It is realistic. The aircraft wants to weather vane into the relative wind and at a certain speed the tail will be completely unloaded and the pressure of the relative wind on the tail and the body of the ship will make it want to turn back into the wind.


Edited by Jester986
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About the right skid low. She actually has a right roll in hover of 2°. This is not much but she is very light too.

 

Let me assure you, we evolve and learn new stuff with new modules too. I can not talk about it yet, but the last check we did yesterday and comparing real pictures with the picture i transferred to one of our product consultants unvield that in the super heavy weight condition some helicopters have a huge rolldegree in hover.

That is all i can say right now about hanging skids in translating tendency conditions.

 

About the other modules, well after the sales i finally have all helos available in DCS and compared them all. I do not want to make official statements about the other products, but some feel more realistic then others just by the pure feeling.

I talked a lot with the pilots of my contact list. Some of them fly the huey for living like Jester also presented and surprisingly the once I talk to do not like the Huey for the way the cyclic is programmed. I have no sticktime on the Huey in RL so I have to listen to the once that do and learn from them.

 

Fact is, DCS is great for what it is, YES, "a game" and it goes very far in terms of getting closer to reality then others that are on the market way longer.

So I still enjoy the Gazelle at the end of the day, although I assume through testing and developing this module and still using it now and then I can claim that I have way mor then 500 hours on her, probably closer to 1000.

 

What I can say though in the name of the team is, that we hope to shout out some news about new stuff this year, but some benchmarks have to be meet and some milestones also have to be passed to actually unviel anything of our future stuff.

We still plan great stuff and even beond what we have released and plan to release as next module and I assume the story about what feels right or wrong will stay the same all the time.

 

Nevertheless I wish all of you a happy flying and while I look at my screen and see on my 2nd screen something awsome I have a big smile of joy on my face.

 

Ohh and I know already now that on first insight people will start to talk about the flightmodel, although they can only see stuff but not have first touch :D

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Fair enough on that skid! Haha guess I just didn't notice. And I don't mean to get off topic but to refine my statement on the Huey I like it too and its a good model, but when I'm throwing it around a little more aggressively is when it doesnt feel right and on short final on approch to an oil platform.

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She always had the pedigree and always behaved so... in fact the old machine required a solid chunk of work to get a corner level and straight and once mastered she was a machine of speed and intent......

 

To be fair, the old model didn't make sense. You could barely hover with 4 HOTs and 60% fuel without blowing the engine after 1-2 mins (faster if you yawed and increased torque and thus engine strain).

 

I agree with you, though. She's a joy to fly at the moment. Still like to visit the Huey whenever I can. For some reason it feels more... raw. :)

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One other thing I'd like to see implemented is a little more translating tendency and right skid hanging low,

 

Hum. If I understand helicopter aerodynamics correctly, it should be the left skid hanging low, if any. And this issue is most likely addressed by the SAS. Newer helicopters tilt the rotor dish slightly to compensate for the natural translation tendency.

 

I'm curious, do you want to see these features because you know the Gazelle to be having these flaws or because you're used to them from other helicopters, specifically the Huey that has a very pronounced translation/roll tendency?

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Counter clockwise rototating, American and I believe Augusta, hang left skid low. Even if like the 206 they have a cant in the rotor system to compensate for translating tendency. Because a left tilt in the rotor mast or a left cyclic input is the same thing as far as the helicopter is concerned. The right skid would hang low because the rotor system rotates the opposite direction in the gazelle. So torque, tailrotor thrust, and translating tendency are all the opposite direction. And I'm comparing it to my experience flying an Astar, a descendant of the gazelle but as a stated an admittedly different helicopter.

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Dear community,

First of all thank you for your time and effort to speak about your thoughts on the Gazelle.

Let me roll up the last post from last to first.

 

About bank angles of the Gazelle a very important fact has to be known. As soon the AP and the gyro are activated, another system is running in the background to enhance flightsafety and an easier controlability of the helicopter for combat use. This system is callaed "SAS", as far I remember the correct name is Stability Augumentation System, but I would have to check that again, which is not im portant for the function it provides.

This system is designed to support the pilots and counter tendencies of the airframe that you try to neglect if possible to increase safety of flight during combat. According to the french pilots the system has 2 sides, a good and a bad one. Good one is that it enables you to fly semi automatic in cross country flights. Bad part is, if you fly more aggresiv you have to fight the systems tendencies, which is the reason why some of the pilots switch of the AP or the gyro for example.

I also switch of the trim when I fly her in DCS, then she feels even more natural to me, but that is just me and everybody has to find thier preferred way of flying her.

This SAS has no real activation button by design in the SA342M cause it is directly linked to the gyro and the autopilot.

As soon you switch off certain functions the SAS is also deactivated.

Another important factor about the Gazelle is the design of the rotorsystem. I often read that people like to compare the Gazelle and the huey. Yes both have the same phyisical laws applied, BUT, they both have different rotordesigns, not only the ammount of the blades and the width of the blades over the cord of the blade, no, the airfoil is different and very importantly, also the rotorsystem itself is designed different. The blades of the Gazelle are capable of flap and feather independently which also changes some flightbehavior in favour of the Gazelle, and no, the blades of the Huey are not capable of doing the exact same. As far I remember the blades of the Huey are only able to flap through the axis of the hinge. Also weight and distance between center of mass and rotor center are different, including the relativ positions between, mainrotor, tailrotor and center of mass, which is for example a reason why the Gazelle has literally no tendency of roll when you apply yaw. Compared that with a huey it has to be stated that both fly different and according to one of the testpilots in our team, who flys the huey for living, plus one of his buddies has over 10000h on the huey and knows the DCS huey, the flightmodel has its flaws too, which I myself can not comment, cause I have no experiance with the huey other then in DCS, so for me, in regards to the huey, I am at the same seat of opinion like the majority of the customers and think it is great.

One factor I have to add about the SAS too. This system enables the autohover of the helicopter too. Without it the SA342M would not be able to autohover or even slave itself to the Viviane sight.

 

Sc_neo pointed out that the Gazelle centers itself slower then the MI8. I do have the DCS MI8 since nearly 2 weeks now and know little to nothing about its avionics. I assume that the MI8 does not have a SAS, but as stated, I do not know, so the next thing is pure speculation. If it does not have a SAS the centering tendency of the MI8 is linked to the pendulum effect, that is more pronounced to heavy helicopters then to light once, where you feel little to no pendulum effect, which also depends on thier relativ design.

 

About Focha. I am not sure what your intentions are, but I have reviewed your former statements and compare it to yours now and they are the complete opposite. First you complained about fm issues that were by far changed now and now you complain about the fact, that the helicopter keeps it roll, which you were complaining about before, that it was not doing what I just mentioned. Not sure if I misunderstood something, but right now I am not sure where you want to travel with your statement.

 

I am happy to talk about aspects of helicopter flights all the time, but keep in mind, EVERY helicopter flys different and also DCS huey and DCS MI8 have flightmodel flaws, which I have seen myself. But I am not discussing any other module that is not our own, which would not be fair and I hope that we do not have to compare DCS huey and DCS Gazelle all the time to explain things, cause explaining and comparing flaws with flaws just make things worse and I would not like to judge other modules in comparrison with ours. I am certain the people who made the other modules have thier valid information why the modules are the way they made them. Same apllies for us.

 

@Focha, please make sure that the FFB options are turned off. One of the pilots was bitching about the Gazelle too, until we compared settings and figurred that FFB was activ, although he uses a none FFB stick.

 

Hi,

 

First off all... I am not bitching.

 

What I am giving is my experience of the module based on some airframes I fly and flew in real life.

 

I don't know if my first post contradicts this one. What I know is that the Gazelle you are modelling feels wrong to me based on my real life experience with other helicopters.

 

But be sure that the first Gazelle I find, I will ride it to have comparison of the same model.

 

I fly in real life the AS365 N1 which is a big brother of the Gazelle and I've flown also AIII which is a older brother. AS365 have a SAS/AFCS system but I don't know how much alike it to the SAS/AFCS system of the Gazelle.

 

What I would expect from my personal experience is that without SAS/AFCS/AP a helicopter is a helicopter. It is back to basics, unless the Gazelle is a very special helicopter different from all the helicopters I have flown.

 

Ones heavier others smaller, all traditional helicopters feel the same, even coaxial ones, although more sluguish in some flight dynamics, but all act a bit the same.

 

My intentions are simple: unless I feel right about the flight dynamics of your helicopter I will tell you otherwise. Sorry for the blunt honesty here.

 

Right now, there are certain things in your FM that are not in par with my personal experience of the real world.

 

For example, I've never flown a Ka-50 but I've flown a Ka-32 and the Black Shark is really there.

 

What I am trying to say, is that your helicopter dynamics does not feel right. One of the things I have noticed (and I didn't extensively tested the flight model) was that the helicopter tends to remain in the same attitude when there is not input... even with SAS/AP off.

 

I have a Microsoft FF2, I will try to see if it is the FFB and report it back.

 

Thank you for your reply and sorry if I didn't explain myself to you.

 

Kind regards.

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Regarding the right side skid being the last to left the ground or the first to touch it... helicopters are very susceptible to weight and balance and other conditions, like wind, etc...

 

For example, in AS350 B3, when I fly alone and with full tank, the last part of the skid to left the ground is always the rear of the right skid (spring) when I have full load of fuel and people, the helicopter leave the ground almost with both skids simultaneous.

 

It depends on the situation...

 

I can give you another example. I still remember when I was in the school flying the R-22, there was a huge difference flying with instructor and without one.

 

One of the things I felt immediately when took off the first solo flight, was the helicopter tendency to have nose up and the rear of the skids to left the ground last, when I was with an instructor, they both got to the air almost parallel to the ground.

 

So, we cannot give a round number on the amount of inclination a helicopter has, since it is highly susceptible to mass and balance and other effects, like side wind, etc.

 

Cheers.

 

PS: Generally speaking, a clockwise rotor will have a tendency to have the right skid off the ground last and first on landing, and a counter clockwise rotor the left one. But this is not always true and is determine by other factors, W&B, wind, design, etc...


Edited by Focha

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When I was flying the Astar I was always light as you said and always had the nose up and right skid low. Anyway as to what your talking about with the attitide... I did a ferry flight this morning in a 206L4 and remembered to take some video, which I sent to borchi and he'll post. You'll note that When I put right cyclic in it continues to roll until I neautalize it. It then holds the bank and I have to put left cyclic in to level the ship. True a 206 is not a gazelle but as you said a helicopter is a helicopter... Obviously were not going to agree and it sounds like you have much more experience then I do in Europcopters, my suspicion is though that our difference in opinion come down to our rigs. Do you have an older unused joystick you can remove the centering spring from? That made all the difference in the world in the feel of all the helicopters for me.

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