Behaviour at high alpha

[Jax37]

Hi there,

 

First of all, Im a big fan of the DCS serie, excellent work!

 

Little about my self, I have never flown a real, KA50, A-10 or P51(yet...) but I do have about 4000h spread out on helicopters, airliners and aerobatic planes and my comments below are general observations based on my aviation experience and therefore maybe not 100% correct for the P51. Although my bet is that they will be applicable.

 

Im not very convinced of the flight behaviour during high alpha and especially combined with high G [read dogfighting]. All planes I have ever flown will warn you of an impending stall. Either naturally by buffeting, or artificially by visual or aural warning, by stick shaker or on some military planes rudderpedal shaker (!!). Or a combination thereof.

The P51beta however will just start rolling and then snaping to the left when increasing Gs and alpha during coordinated flight (and to the right with power off) I bet the real plane would shake quite a bit before a wing stalles and you would also feel it in the controls. A more accurate simulations would be to implement buffeting in the cockpit (shaking) and maybe also a low frequency sound. In some planes the buffeting of the fuselage is actually hearable (not to mention the application of high Gs!).

 

Also while Im at it. The blackout effect by g-forces are set way to low. 6-7gs without g-suit and pressure breathing is hard but not impossible, the blackout in the sim starts to early, already below 6g.

 

Blue skies,

Jax

[Brisse]

Hi!

I have never flown anything in real world and I respect your opinion but I have heard Mustang pilots describe high AOA and stall behavior of the plane and it sounds exactly like it feels in DCS: P-51D.

[Suchacz]

I think, that this is still WIP...?

 

It sounds logical, that if Mustang loses pressure above its wings, the prop momentum starts turning the whole aircraft... imho :smilewink:

[lobo]

Hi there,

 

First of all, Im a big fan of the DCS serie, excellent work!

 

Little about my self, I have never flown a real, KA50, A-10 or P51(yet...) but I do have about 4000h spread out on helicopters, airliners and aerobatic planes and my comments below are general observations based on my aviation experience and therefore maybe not 100% correct for the P51. Although my bet is that they will be applicable.

 

Im not very convinced of the flight behaviour during high alpha and especially combined with high G [read dogfighting]. All planes I have ever flown will warn you of an impending stall. Either naturally by buffeting, or artificially by visual or aural warning, by stick shaker or on some military planes rudderpedal shaker (!!). Or a combination thereof.

The P51beta however will just start rolling and then snaping to the left when increasing Gs and alpha during coordinated flight (and to the right with power off) I bet the real plane would shake quite a bit before a wing stalles and you would also feel it in the controls. A more accurate simulations would be to implement buffeting in the cockpit (shaking) and maybe also a low frequency sound. In some planes the buffeting of the fuselage is actually hearable (not to mention the application of high Gs!).

 

Also while Im at it. The blackout effect by g-forces are set way to low. 6-7gs without g-suit and pressure breathing is hard but not impossible, the blackout in the sim starts to early, already below 6g.

 

Blue skies,

Jax

 

Have a read though this pilot report:

http://www.airbum.com/pireps/PirepMustangBurch.7.html

[ATAG_Snapper]

That report was a good read -- pretty much describes my perception of the DCS P51D, especially flight departure. Apples-to-oranges, certainly, but far, far, different to anything I've experienced in other current WW2 aircraft sims.

[EtherealN]

Either naturally by buffeting

 

See this sticky thread: http://forums.eagle.ru/showthread.php?t=87556

 

Specifically:

"4. Other

 

Buffeting and shaking will be added in the near future."

 

P-51D is still in active development and this is a beta. :)

[Pyroflash]

I love thew whole "Oh, you have 4,000 hours in some aircraft other than the one we are talking about? Your views must be wrong" attitude people take on here. Respectfully, I doubt that the P-51D's stall characteristics are such that the aircraft doesn't do some sort of shaking before stalling out, and given the aircraft that I have flown, this can mean a number of different things. However, I have never, ever flown an aircraft that DOESN'T give some sort of physical warning as to an impending stall, and see no reason why the Mustang would be any different.

 

**Disclaimer: Yes, I am fully aware that there are some larger aircraft that will stall out with nothing more than an aural warning. This has led to crashes and accidents that have forced most of the designers of these aircraft to implement some form of stick shaker in order to simulate the physical effects of a stall in the cockpit.

 

Especially since Matt has come out and stated

 

"Buffeting and shaking will be added in the near future."

 

DCS is a GAME that SIMULATES AN AIRCRAFT TO THE BEST OF ITS ABILITY. Please do not forget that simulations will inevitably get a multitude of things wrong, and that the only way to get 100% fidelity is to go out and fly the real aircraft.

Edited June 16, 2012 by Pyroflash

[Nate--IRL--]

AFAIK a noted characteristic of the P-51 was that any sort of physical stall warning occurred very close to departure. You get very little warning of departure.

 

Nate

[159th_Viper]

P-51D 'The Little Witch' Flight:

 

 

Interesting to note start-procedure/takeoff/landing and stalls in the loop.

 

 

Another training flight vid from The Little Witch:

 

A0hNMKnJk6k

 

See how she stalls from about 3:40min. Visually I cannot pick up any signs of an impending stall - see if you can. Also interesting perspective on all the flight maneuvers.

Edited June 16, 2012 by 159th_Viper

[Double_D]

nice vid..some interesting points to know like how you do flaps to make a tighter turn...:thumbup:

[effte]

Nice vid indeed.

 

You'll usually feel the rumble of the turbulent air coming off the wing impacting the horizontal stab. Then you have the feel of the controls going all mushy on you.

 

The buffet would be right after the point where the instructor says, and I quote, "Get ready for a buffet". :thumbup:

 

It's not something you'll see in a vid, unless the camera mount is shaky.

 

Also of interest is the fact that he stalled out closing on the top of the loop, caught by the instructor in approximately 90 degrees of roll - and he wasn't flying when it happened.

 

Interesting how he has the tail off the ground in about five or six seconds, after only 200 m of ground roll - with very little swing. I doubt it's at 61"/3000 either. That's not something that's doable with 100% consistency in DCS at the moment. If he couldn't do it 100% of the time, we wouldn't see him doing it at all in such a rare aircraft.

 

(You also see plenty of people doing formation takeoffs in vintage Mustangs on Youtube. Not something they'd do if directional control was much of a challenge.)

 

The wheel landing is certainly not easy to replicate in DCS at the moment either.

[effte]

I love thew whole "Oh, you have 4,000 hours in some aircraft other than the one we are talking about? Your views must be wrong" attitude people take on here.

 

Haha, no kidding!

 

And then there's the "I've never flown outside of my armchair, but flying a pure-bred fighter is bound to be difficult and this is difficult so it must be right" crowd. :D

Edited June 16, 2012 by effte

[159th_Viper]

The wheel landing is certainly not easy to replicate in DCS at the moment either.

 

How so?

 

Ygx8r4ULRBA

[Double_D]

How so?

 

Ygx8r4ULRBA

 

Nice Landing " Shrek ":thumbup:

[effte]

Viper,

I know that English isn't your native tongue, but I still would have expected you to catch the difference between 'easy' and 'possible'. ;) Now, post a vid of you doing that five times in a row, without relying on the VSI (another TLA for your enjoyment!) and without cheving up the first 450-650 meters of the runway trying to grease it on. In the vid, a beginner had it down (with a little help) in slightly more than 300 meters.

 

Edit: Second vidm on the T/O roll - "There's 50, start pushing forward elevator". I expect that to be 50 KIAS though, rather than mph, as he refers to airspeeds in knots in the first vid and probably has a different ASI than original. Still, 56 mph. Pushing the tail up. No directional control issues. A beginner on the type at the controls, being coached to do it by a pro. Hmm.

 

Also, prior to the stall: "Feel that little vibration? Pull a little harder." And then, departure. What more do you need to show that you can hold it on the ragged edge riding the buffet? You have to have that camera shake? :D

 

Moot point though, I think we're getting it soon.

 

Cheers,

/Fred

Edited June 17, 2012 by effte

[159th_Viper]

:wallbash:

 

Viper,

I know that English isn't your native tongue....

 

Guess again.

 

but I still would have expected you to catch the difference between 'easy' and 'possible'. ;)......

 

You know what, us testers rely inter alia on people such as yourself to identify and track down issues. In doing so, we have time and time and time again begged for issues to be reported/identified as comprehensively as possible in order to aid in the reporting process.

 

Which is why I got hiccups when you alledged 'certainly not easy'.....

 

I managed to placate my stressed vein and, giving you the benefit of the doubt in thinking that an issue exists that needs addressing, again requested more information, hence my post. It's inferred, but I'll say it again, 'certainly not easy' is useless for me or anyone else for that matter to attempt further investigation into a potential issue.

 

 

Now, post a vid of you doing that five times in a row, without relying on the VSI (another TLA for your enjoyment!) and without cheving up the first 450-650 meters of the runway trying to grease it on. In the vid, a beginner had it down (with a little help) in slightly more than 300 meters.......

 

I am still none the wiser. What is currently wrong, apart from, in your opinion, being too difficult?

 

 

Edit: Second vidm on the T/O roll - "There's 50, start pushing forward elevator". I expect that to be 50 KIAS though, rather than mph, as he refers to airspeeds in knots in the first vid and probably has a different ASI than original. Still, 56 mph. Pushing the tail up. No directional control issues. A beginner on the type at the controls, being coached to do it by a pro. Hmm.

 

Also, prior to the stall: "Feel that little vibration? Pull a little harder." And then, departure. What more do you need to show that you can hold it on the ragged edge riding the buffet? You have to have that camera shake? :D

 

 

These issues are already addressed in other threads and confirmed as being a WIP - no need for analysis at this point.

Edited June 17, 2012 by 159th_Viper

[Smokin Hole]

The lack of decent stall warning in a sim is fairly common. It doesn't mean that the aerodynamics are wrong, just that the PC environment sucks. FFB helps. But honestly the best work-around I have ever seen is the aural warning in Warbirds. It was totally unrealistic but perhaps in the way it simulated the natural awareness of an oncoming stall, it was the most realistic of all. (No, I would never want that feature in DCS).

[Smokin Hole]

Regarding landings: Landing 3 points is pretty easy IMO. What is difficult are wheel landings. I excuse my inability to do them consistently with grace by telling myself that the tendency for the CG to pull the tail down slightly at touchdown is exaggerated. You may disagree with that theory but it preserves my ego and I am therefore sticking with it.

[HiJack]

How so?

 

Ygx8r4ULRBA

 

Are you sure you are not in Game mode Viper? :thumbup:

[effte]

Viper,

regarding the English, that was strictly tongue-in-cheek, seeing as how people from your part of the world managed to fail in the ICAO English language proficiency tests in spite of being English-speaking.

 

The Stallion 51 vid is certainly not easy to replicate. Try it. In the real world, pilots with relatively few hours total, and very few hours on type, have been sent to fly these aircraft under abysmal weather conditions, under extreme stress, heavily loaded, from rough runways. Yet, the type wasn't plagued with take-off and landing accidents - unlike certain other types in theatre.

 

Today, we see wheel landings and formation takeoffs being performed routinely, mostly by very experienced pilots but also by pilots with not all that many hours on type. We see the tails being actively lifted at under 60 mph by beginners without directional control issues. We see 20 knot crosswind takeoffs off concrete runways. All this in rare vintage aircraft which the owners are extremely vary of exposing to any kind of risk.

 

This, you cannot replicate in DCS at the moment. There is a difference between what we are seeing in DCS and the real world.

 

Taildraggers can bite, and they will if you give them an excuse. However, most people manage to do thousands of flights in all conditions without ever really getting into trouble - including on this particular type.

 

However, as I feel the final release is still some way off, with the team hard at work, I think it is way too early to get all upset. It's what I would expect at this stage. Keeping the (perceived) issue on the table is all I want to do at this point.

 

We are spoiled though, as DCS:A-10C was pretty much spot on in the flight dynamics from the open beta release IMNSHO.

 

As for details on what is wrong, all I can do is guess. To attempt any kind of detailing, I'd need to have access to engineering data (aero coefficients/moment arms, CM locations, tyre models etc etc) which I am not privy to. The best I can do is do my best to have those who do have access to flight model data know that I, from my vantage point, perceive a discrepancy between the flight model and the real world, in the hope that they will indeed have a look at it eventually.

 

I do have a theory or two, with some in-sim data I think backs them up, but I'm not quite done thinking there. To post them at this point would be too far out on the speculation side of the spectrum.

 

These issues are already addressed in other threads and confirmed as being a WIP - no need for analysis at this point.

 

Directional stability is confirmed as WIP, apart from the rudder hinge moments? Can't find it in the official WIP sticky.

 

Cheers,

/Fred

Edited June 17, 2012 by effte
Viper's edit

[Panzertard]

Sorry to jump in so late, but didn't we try to get a bit more data from ED about this, Viper?

Not sure if we got the answers by Yo-You yet?

 

(PS, a poor attempt to mask my own poor skills on the topic) ;)

[Nate--IRL--]

Sorry to jump in so late, but didn't we try to get a bit more data from ED about this, Viper?

Not sure if we got the answers by Yo-You yet?

 

(PS, a poor attempt to mask my own poor skills on the topic) ;)

 

Fly the P-51 later today and note the difference to earlier builds, at the edge of the envelope. Even better if you have FFB ;) .

 

Nate

[Jax37]

See this sticky thread: http://forums.eagle.ru/showthread.php?t=87556

 

Specifically:

"4. Other

 

Buffeting and shaking will be added in the near future."

 

P-51D is still in active development and this is a beta. :)

 

Excellent! Then someone's working on it, and in the mean time I'll go take a quick type rating on the search function :book:

[159th_Viper]

Sorry to jump in so late, but didn't we try to get a bit more data from ED about this, Viper?

Not sure if we got the answers by Yo-You yet?

 

(PS, a poor attempt to mask my own poor skills on the topic) ;)

 

No, all matters are being attended to. As for wheeler landings, they are spot-on provided that parameters are met and in the absence of substantive allegations to the contrary, cannot fault those at this stage. Will revisit after next version release.

Edited June 17, 2012 by 159th_Viper

[leafer]

That article pretty much described DCS P-51D.

 

I was at 6,000 feet and I thought I'd never get that thing down from altitude. At 175 mph it has a glide ratio of nearly 15:1; it will glide three miles for every thousand feet of altitude. I tried dropping the nose and diving down at 250 mph, but then found when I got to the altitude I wanted, the airplane didn't want to slow down, and I'd gain altitude trying to bring the nose up. So, this is what a high-performance airplane is like. The Mustang is so slippery, that you really have to work to get it down to 200 mph. Under 200 mph, it's fairly easy to control the speed, but above 200, even the slightest jerk on the stick picks up 500 feet and may not even budge the airspeed. I made lots and lots of circles getting down to pattern altitude.

 

I did wonder if it was really this difficult to lose speed. A hung of metal this size doesn't want to slow down? This can't be realistic! Good job, ED.