Author Topic: Stability with the Ki-84 (Read 2807 times)

Karash · « **on:** May 01, 2007, 03:41:29 PM »

Disclaimer: I do not claim to be an expert at AH...that is why I am posting here.

The Ki-84 is my primary bird...and has been for quite awhile. Throughout this time I have slowly come to the conclusion that 1.) the flight model gets hosed or 2.) there is some sort of weird AOA issues inheirent with its airframe. The reason I bring this up is that I have talked with some other Ki-84 pilots and they all confirm the characteristics that I am about to discribe.

It seems to me that if I am dogfighting with an opponent, with a lot of manuevers both in the vertical and circling (basic knife fighting), the Ki-84 loses its stability to such an extreme that barely moving the stick will cause it to stall...even when going over 200mph IAS. At speeds that flaps are no where near an option to help you turn or keep you up in the air. This seems to happen at any altitude...but a common theory is it is most prevailent when you enter a fight with a lot of speed, then dump it suddenly while angling to attack a enemy's six.

I have been in situations both on the deck and at 15k feet where I have over 250mph speed and any stick movement will start the stall noise. You litterly have to treat the joystick so gingerly that often you cannot come around on your target's six even though you know your plan should be capable to. My only wingman Zes in my squad has the same problem, and I have talked to a few other pilots that again confirmed their problems.

Is there a problem with the game? Or is it something with the actual Ki-84 airframe causing this? Or am I just a dweeb?

I have not been in any other aircraft in AH2 that exhibits this behavior...but again I dont profess to be any sort of expert.

Could I get some opinions out there?

Karash · « **Reply #1 on:** May 01, 2007, 03:42:14 PM »

I forgot to add that I do not use Combat Trim nor the Stall Limiter.

Krusty · « **Reply #2 on:** May 01, 2007, 03:50:31 PM »

Hrm... I, too, am no expert, but I have done well in the Ki, and enjoy flying it.

I have not experienced this problem. You might check the stick mapping and click "advanced" and see if your controls are spiking (and throwing it into invisible stalls).

Usually that plane glides on rails for me.

Karash · « **Reply #3 on:** May 01, 2007, 04:10:42 PM »

Well Krusty you are definately a better pilot than I am. I will check my joystick to see if its spiking, but I doubt it is since no other plan exhibits this performance degredation like what I see in the 84.

Krusty · « **Reply #4 on:** May 01, 2007, 04:15:16 PM »

That's debatable...

Are you sure you're not just snap-stalling? You can do the same with the 190 at almost all speeds. It does that because the elevator authority is very good at almost all speeds.

Usually, though, that requires rapid full-deflection pulls, and you described something different.

When in doubt, get it on film.

SuperDud · « **Reply #5 on:** May 01, 2007, 04:29:35 PM »

KI has a mean snap stall that takes a lot of training to get use to. Practice stall fighting it for a few months and see if that don't help.

Karash · « **Reply #6 on:** May 01, 2007, 05:04:17 PM »

One thing that might cause this problem is that I move my elevator trim to max elevation anytime I need to pull back on the stick. Do you guys think that is contributing to this? It seems to help me all the time in my turning ability....so I would hate to get rid of that technique.

Krusty · « **Reply #7 on:** May 01, 2007, 05:11:16 PM »

I wouldn't recommend that, personally. Try it without doing that.

Karash · « **Reply #8 on:** May 01, 2007, 05:13:02 PM »

btw, what causes a "snap stall" anyhow?

Krusty · « **Reply #9 on:** May 01, 2007, 05:18:20 PM »

Rapidly exceed the AOA, the wing stalls because air is disrupted, and because the air is disrupted the other wing swings around really fast, often flipping you over on your side or upside down.

EDIT: Something like that.

Domin · « **Reply #10 on:** May 01, 2007, 05:39:13 PM »

KI-84 has an odd snap to it. It's a great plane however and is what I started in (I prefer the 109f4 and 109G2 now, do try them, they are closer to the KI84 then most think).

Here is a couple fun KI-84 films:
KI-84 (.ahf)

FX1 · « **Reply #11 on:** May 01, 2007, 05:43:24 PM »

I would go ahead and use combat trim. I found that if your not in the DA in most birds its ok to go ahead and use it. I fly with combat trim and da with it off in the 109's and p38. Just something else to think about in the middle of a fight that doesn't give you that much if advantage.

SuperDud · « **Reply #12 on:** May 01, 2007, 06:35:16 PM »

Quote

Originally posted by Karash
One thing that might cause this problem is that I move my elevator trim to max elevation anytime I need to pull back on the stick. Do you guys think that is contributing to this? It seems to help me all the time in my turning ability....so I would hate to get rid of that technique.

Turning trim on and off is still an on going debate. Some says it works, others that all it does is not force you to pull all the way back on the stick. I'm of the school that you gain no significant advantage from manual trim. HTC himself commented that it won't help with turn rate.

Ack-Ack · « **Reply #13 on:** May 01, 2007, 07:46:32 PM »

Quote

Originally posted by Karash
One thing that might cause this problem is that I move my elevator trim to max elevation anytime I need to pull back on the stick. Do you guys think that is contributing to this? It seems to help me all the time in my turning ability....so I would hate to get rid of that technique.

Sounds like you're getting into a snap roll due to an accelerated stall. Try adjusting your stick scaling some. Also, turn your stall buzzer sound all the way to 100% and learn to listen to it so you'll know when you're riding the edge of an accelerated stall.

ack-ack

BaldEagl · « **Reply #14 on:** May 01, 2007, 08:42:01 PM »

Quote

Originally posted by Karash
btw, what causes a "snap stall" anyhow?

It's actually called a snap-roll.

When you stall one of a few things can happen.

If the wing opposite the direction of engine torque stalls you'll typically go into a flat spin. This happens because you're trying to drop that wing, probably to bank and turn at stall speed. At that low a speed engine torque won't allow you to drop the wing, thus it stalls and the other keeps coming around causing the spin.

The opposite of this is a snap-roll. If you're begining to drop the wing to the side of engine torque at to low a speed, engine torque will effectively help drop that stalled wing for you but much faster than you anticipated because the other non-stalled wing keeps coming helping to accelerate the effect.

The final regular stall happens when you're nose high and stall both wings. The nose will dip and the plane will begin to spin in the direction of engine torque nose down until it gains enough airflow over the wings for you to re-gain control.

In any spin recovery consists of cutting throttle, ruddering hard in the direction opposite the spin, pushing the nose down and recovering from the dive once the plane stops spinning.

Recovery can be difficult at times and, as most stall fights happen on the deck this is a common cause of augering when in one but learning to walk that fine edge of an unrecoverable stall while out-manouvering an opponent is one of the most rewarding types of fighting in my opinion.

I also found this tidbit at: http://www.aopa.org/asf/publications/topics/stall_spin.html

Many pilots believe that an airplane won't stall until it reaches the stall speed (Vs) published in the POH. Stalls and spins both result from a disruption of airflow over the wing. It is important for all pilots to know that a stall or spin can occur at ANY airspeed and at any attitude. If the wing reaches its critical angle of attack, it will stall. A spin will result when one wing has a lower coefficient of lift than the other.