Selected Stall Speeds

[hitech]

Stoney: Your numbers are in the ball park. But if you wish to use them for CL calculations you will also have to take into account Horizontal stab forces do to CG's.

HiTech

[thorsim]

The airfoil did not change. The structure was lightened but I have no information that it would have got stronger, only lighter -maybe it was just a bit overdone in earlier variants? The rear fuselage length was not changed. It was lightly modified structurally e.g. the aux tank access hatch was put in and side access hatch was larger in A8.

ok i will re check my sources, question if not fuselage length then what do you suggest was done to offset the COG rearward again after they added the weight upfront ?

EDIT: NM found it, they fuel in an aft tank, sorry for the confusion.

[FLS]

Well, maybe if they hadn't designed so much airfoil thickness taper into the wing design.  Almost all of the planes in-game suffer from tip stall before root stall.  That's why they want to roll over on their backs when they stall.  Washout, IMO, is overrated, and in the case of most WWII aircraft that had it, useless.

Edit: Mixed up and down. 
Wouldn't the wingtip with the trimmed down elevator have a slighter higher AOA than the trimmed up elevator and stall first? Even though the difference is small the loss of roll damping at the stall combined with a slightly higher AOA seems like it would be enough to initiate a roll.

[hitech]

Wouldn't the wingtip with the trimmed down elevator have a slighter higher AOA than the trimmed up elevator and stall first?

I assume you are meaning Aileron not Elevator. If this is case the answer is no, but your thinking is correct. Since the Aileron is creating more camber in the wing, its Max AOA is going down, and hence it will stall sooner just as if it had a greater AOA.

HiTech

[Krusty]

The only changes in the A6 wing was to allow better incorporation for the internal weapons trays and the larger weapons setups that the A-5 could not handle. Maybe it was "lighter" by removing the ribs directly inside the ammo compartement, but overall that's negligible. You'll find wild claims all over the Internet that the wing was greatly enhanced in either weight savings, strength, span, or any number of other claims but the real answer was: It's the same wing. It just just holds different guns.

The overall airframe dimensions between our A8 and A5 are identical with the exception of the bulged cowling to cover the larger guns.

The idea here is interesting, but I don't think it will be very useful.

You might weight a A5 down to the same level as an A-8, but that won't necessarily mean much. Even if the level stall speeds are the same, the turning ability will be greatly affected by the CoG shift of all this added or removed weight ballast.

So while scientifically interesting, it won't mean much in comparing actualy combat performance IMO.

[Stoney]

Stoney: Your numbers are in the ball park. But if you wish to use them for CL calculations you will also have to take into account Horizontal stab forces do to CG's.

HiTech

i.e. trim analysis?

[Stoney]

You might weight a A5 down to the same level as an A-8, but that won't necessarily mean much. Even if the level stall speeds are the same, the turning ability will be greatly affected by the CoG shift of all this added or removed weight ballast.

So while scientifically interesting, it won't mean much in comparing actually combat performance IMO.

Assuming all the weight is being added in the wing, which would probably be close to the CG anyway, I believe the weight increase would have very little impact on turn performance, with respect to CG.  My point is/was that the same wing planform, with the same airfoil, and same wing area, stall speed will be the same, at the same wing-loading.  I guess I should test to see.

[FLS]

I assume you are meaning Aileron not Elevator. If this is case the answer is no, but your thinking is correct. Since the Aileron is creating more camber in the wing, its Max AOA is going down, and hence it will stall sooner just as if it had a greater AOA.

HiTech

Yes I meant Aileron. Brain shut down earlier than usual today. So the down Aileron would also effectively change the incidence and washout for the side that the aircraft wants to roll towards from the spiral slipstream.

[Krusty]

Assuming all the weight is being added in the wing, which would probably be close to the CG anyway, I believe the weight increase would have very little impact on turn performance, with respect to CG.  My point is/was that the same wing planform, with the same airfoil, and same wing area, stall speed will be the same, at the same wing-loading.  I guess I should test to see.

But it won't be... Lightening the A8 will remove weight from the fuel tanks, making the tail lighter. Weighing down the A5 will add gas to the tanks, making the tail heavier. Just sayin' 

[hitech]

i.e. trim analysis?

I.E. if wing cl is 6" behind cg with a 15 ft tail.

A 10000 lb plane would require about 10333 lb lift for level flight. (10000 * .5 / 15) + 10000

HiTech

[Ardy123]

I.E. if wing cl is 6" behind cg with a 15 ft tail.

A 10000 lb plane would require about 10333 lb lift for level flight. (10000 * .5 / 15) + 10000

HiTech

This is probably a dumb question but isn't the h-stab of most planes have symmetrical camber, thus creating equal lift on both directions of the y-axis? ie, if the plane is horizontal, the lift force up is the same as the lift force down? I don't profess to be an aeronautics engineer so I may be way off with this.

[FLS]

Lift is created by angle of attack. I believe camber is more about efficiency than usable lift.

[hitech]

Ardy, if the Cl of the wing is behind the cg, the plane is trying to always pitch down. This must be compensated by a down force from the Horizontal stab/elevator to keep the plane from pitching. That down force then must be compensated by more lift from the wing, or the plane would be sinking but not pitching. Hence nose heavy planes require more lift to fly.

HiTech

[Stoney]

I.E. if wing cl is 6" behind cg with a 15 ft tail.

A 10000 lb plane would require about 10333 lb lift for level flight. (10000 * .5 / 15) + 10000

HiTech

What happens with increased load factors?

[FLS]

Stoney wouldn't it be proportional? A 2G load would require 20666 lbs of lift if 1G requires 10333? I'm guessing that there's something I'm missing or you wouldn't have asked.