Author Topic: 109G/la-5/7 and the slats (Read 7098 times)

Mace2004 · « **Reply #165 on:** November 11, 2005, 06:08:09 PM »

Vn (or VG) diagrams are velocity (V) over G (n). The vertical scale is G-load and horizontal is speed. There are different charts for different altitudes. Your lift curve starts at 1G and ramps up with speed until you reach the plane's G limit (also ramps down for neg G). If you go above the lift line you stall before you reach your G-limit. If you go above the G-limit you overstress your aircraft without using available lift. The right side of the graph is your mach/IAS limit. Using the graph you can determine instantaneous G available for any given speed. Corner velocity is that point where the lift line intersects your maximum G limit and shows that point at which you have the most G available without overstressing the aircraft. This is a point that you typically want to target. Too fast and you're G limited so you can't use all of your available lift. Too slow and you're lift limited and can't generate enough G to get your best turn without stalling. This equates to the speed for max turn rate since G determines turn rate. Note that this says nothing about turn radius just rate. When the diagram includes excess power you can determine the best speed for sustained turns and climb. You can see at what speeds you bleed energy and those that you can sustain or add e

Let's say you check your corner speed and see it's 300 kts but your opponent's is 450 (say an F-4). If you hit the merge co-speed at 450 kts he has his best turn rate available to him while you're G-limited. You can't pull the plane around as quick unless you bleed off that extra 150 kts and since you're fast you're flying a very large radius turn. If his best turn rate is better than what you have available then he gets turned around both quicker and in a smaller radius for a shot opportunity before you. Even if he doesn't get a shot he's gained angles on you and hits the second merge with an advantage. If, on the other hand, you slow to 300 kts at or right after the merge you can get around before him while he screams around in a huge arc. Think about hitting the merge in a Typhoon going 400 and your opponent is a Spit V going 300. Both of you go vertical and you in your typy come over the top only to see the Spit has turned inside you already, reversed and is pulling for a snap shot as you head down on the backside of you're loop. Sound familiar? You wouldn't be surprised if you had both Vn diagrams.

Obviously there's a lot more to consider but overall the Vn is probably the most useful single graph for maneuvering flight. Of course in AH we have a stall limiter; however, it would still be useful. There are those that disable the limiter and even those that don't would be able to use it since you'd know when fast is too fast and visa versa.

Mace

HoHun · « **Reply #166 on:** November 11, 2005, 06:42:44 PM »

Hi Mace,

>Vn (or VG) diagrams are velocity (V) over G (n).

Thanks, I understand. Were they plain V-n-diagrams or did they have some kind of excess power indication as well? Most players know the relative turning abilities by heart, but the relative energy combat capabilities of the aircraft are a bit more dfficult to visualize, and we have not found a good type of diagram for that yet.

Regards,

Henning (HoHun)

Mace2004 · « **Reply #167 on:** November 12, 2005, 02:34:26 AM »

Hohun

Yeah, as I recall they overlayed the Ps data on the Vn. Believe the left vertical axis was load the right was Ps.

Mace

Angus · « **Reply #168 on:** November 12, 2005, 11:31:08 AM »

Mace2004, - Nice input, and very much so.
Did you read the whole thread? Takes patience to ponder through this one, but there is however some meat on the bones.
This is the thread that made me dig quite deep in the debate, and even earned myself a place on HoHun's sig list. Hell, to get some first account word on the slats I even phoned Gunther Rall, lol.
So, great to have all this confirmed, and a good education for some of us

HoHun · « **Reply #169 on:** November 17, 2005, 05:44:40 PM »

Hi Mace,

>Yeah, as I recall they overlayed the Ps data on the Vn. Believe the left vertical axis was load the right was Ps.

We were discussing turn rate over speed diagrams, which we found unsatisfactory. G over speed is not that different - which are the advantages?

Was the Ps information depicted in lines of equal Ps?

Regards,

Henning (HoHun)