Author Topic: Uncovered serious flaw in Mossie's FM (Read 1624 times)

Widewing · « **on:** July 02, 2004, 10:14:50 AM »

As the subject line indicates, I have discovered a huge flaw in the Mosquito's flight model.

I have never seen so strange a departure behavior as is exibited by the Mosquito. Last evening, I chased down a Typhoon and upon killing it, pulled into a climbing right turn to clear my six. Barely pulling 4 g at 350 mph, the Mossie snapped into an uncontrolable spin. Every effort was made to break the spin, but it was unrecoverable. I was at 5,000 feet initially, plenty of room under normal circumstances. This was baffling as I had never seen such behavior flying the AH1 Mossie.

So, I went offline, started film recording and set about duplicating the problem. It was easy enough to do... Pull 4 g or greater and the Mossie snaps into an unrecoverable spin.

I modified my method, basically letting the Mosquito simply stall nose high, power on, with mild back pressure. What happened then is even more bizarre.

Instant snap roll into a spin, I wrestled with it a bit and stopped rotation. Nonetheless, behavior was getting more strange by the second. I watched my true airspeed indicate 120 mph, while the indicated speed went to NEGATIVE 30 mph!!! Meanwhile, the aircraft simply dropped flat, with zero forward motion and almost no rotation. It dropped like dinner plate. Meanwhile, both engines are powered up into WEP. Still, no forward motion, no torque effect... Nothing. No control input possible in pitch, yaw or roll. Below is a link to a short film.

Clearly, the Mosquito's FM allows for behavior that I would term as "unusual".

Mossie weirdness

My regards,

Widewing

Soulyss · « **Reply #1 on:** July 02, 2004, 10:20:17 AM »

I experienced a similar problem in the Bf110 earlier in the week. Don't recall the exact circumstances, but it was in a dogfight and the result was a stall and my plane dropping straight down like a dinner plate, nothing I could did affecting any change.

Replicant · « **Reply #2 on:** July 02, 2004, 10:33:58 AM »

I've had the same problems with the Mossie. During beta I lost about 20 Mossies out of 25 sorties to the snaproll. I find it extremely severe and pleased someone else is experiencing it! I lost another last night, shallow dive to straff a GV, pulled up to avoid hitting ground, spun, dead!

Widewing · « **Reply #3 on:** July 02, 2004, 10:39:31 AM »

Quote

Originally posted by Soulyss
I experienced a similar problem in the Bf110 earlier in the week. Don't recall the exact circumstances, but it was in a dogfight and the result was a stall and my plane dropping straight down like a dinner plate, nothing I could did affecting any change.

I can get the 110 into a similar flat, rotationless drop. However, I really have to thrash the aircraft to do it. The Mossie, on the other hand, is far more unstable than the 110. Snap rolls into stalls are induced with great ease.

My regards,

Widewing

Soulyss · « **Reply #4 on:** July 02, 2004, 10:47:59 AM »

It's quite possible that I abused that 110 so bad it decided it just was going to simply stop flying to get me out of the cockpit.

thrila · « **Reply #5 on:** July 02, 2004, 11:29:00 AM »

heheh i've done this many times when strafing gv's. I haven't done it in a while because i've been flying the mossie lots and think i've found how to combat it. As soon as it develops i shove this stick forward (no rudder)...this'll you get you out of it. You have to be very, very quick though.

Just try ditching the mossie widewing.

Angus · « **Reply #6 on:** July 02, 2004, 12:12:53 PM »

In RL the 110 was prone for flat spinning.
Not sure about the mossie, but its pilots usually gave it a very good word.
But what Widewing shows is really out of the ordinary, - hence, probably a program error.

thrila · « **Reply #7 on:** July 02, 2004, 12:26:38 PM »

Oh i agree it's odd- It's darn scary too.

Seeker · « **Reply #8 on:** July 02, 2004, 12:28:52 PM »

I've had the flat spin in the 110; dropping the gear got the nose down.

Haven't tried the Mossie yet.

You know; it's not so much the FM; as the stall horn that's changed. I used to be able to chandelle up and away looking over my shoulder judging the pull by the black out/stall horn (depending on desperation)

These days those markers are lying to me; and I'm having to fly by the instruments more; and be a lot more carefull about keeping the ball centred.

Karnak · « **Reply #9 on:** July 02, 2004, 02:40:32 PM »

Oh, I've seen this too. Even managed to get of of the flat fall once, IIRC I used the landing gear to do it.

But I've lost more than enough Mossies doing it. Rope-a-dopes are very dangerous to pull in the Mossie if the relative E states are anywhere near to a close thing.

However, other than the generalistic and anctedotal pilot's reports saying it was a joy to fly, I don't have anything that says this is wrong, so I have been silent on it.

I do know that losing an engine on takeoff or landing was a very bad thing in the Mossie, and I personally experienced this in AH1. Liked it too, even though I died.

SELECTOR · « **Reply #10 on:** July 02, 2004, 02:50:47 PM »

the spin is weired ,, and its still too slow

Widewing · « **Reply #11 on:** July 02, 2004, 03:10:02 PM »

I think I have discovered where the problem lies.

You can momentarily (not for longer than 200 milliseconds) jerk the stick to spike the G meter at 7+ G. Of course, the airplane cannot change attitude in response to such a short duration input (watch the film and you don't even see the elevators deflect in response to the spike because I have some damping preset). However, it seems that the software identifies this ultra-brief spike as being sufficient to induce an accelerated stall, despite the fact that the elevators didn't travel enough to induce the required pitch-up.

Why did the G meter spike when there was no attitude change? Is the G-meter tied to stick movement rather than control surface defection or, as it should work, to actual G loading?

Another disturbing factor is that 3,200 hp turning two large diameter props cannot generate the slightest apparent thrust.

Several mysteries here to resolve.

My regards,

Widewing

GScholz · « **Reply #12 on:** July 02, 2004, 09:16:55 PM »

The mossie's flat spin (not really a spin at all) is somewhat weird, but I could break most of them by turning off the engines (they're holding the wings up), but I lost a lot of altitude. The spinless fall is definitively strange.

GODO · « **Reply #13 on:** July 03, 2004, 05:56:16 AM »

Quote

Originally posted by Widewing
Why did the G meter spike when there was no attitude change? Is the G-meter tied to stick movement rather than control surface defection or, as it should work, to actual G loading?

I also noticed that, and this alone is worth another thread.

Spitter · « **Reply #14 on:** July 07, 2004, 03:39:24 PM »

While we're discussing the mossie. I've been flying AH2 offline only and can not even seem to get the mossie off the runway without autotakeoff. What am I doing wrong?
I never had any problems with the mossie in AH1, but the rudder response in AH2 seems too slow and overpowered once it gets moving that I wind up oscillating back and forth until I'm off the runway.
Is it me, or do I need to change my stick settings in some way specifically to fly the mossie?
I don't notice this with any of the other torquey planes I jumped in.

Cheers,
Spitter, aka FATE squadron target drone.