Notice the increase of the WB's Style Defensive Manuevers?

[danish]

AKWabbit
Stop the bs, noone in this thread has "hidden agendas" - at least not the guys from the other sim.
We just cant all be like Wells (thank god :=).

To crave for the numbers, the definite and ultimative mathematical proof, every time a matter is under consideration is bound to stop development.And a good way to stop questions.
Happend to that other sim.

danish

[Pyro]

That's not what I'm saying AKW.  There's nothing hard about looking at what the drag differences would be, it can just be a bit unintuitive, especially if you're not familiar with the basic lift and drag calcs.  
 http://bbs.hitechcreations.com/smf/Smileys/defaultframe.html

My offer to Daff stands.



------------------
Doug "Pyro" Balmos
HiTech Creations

[AKDejaVu]

Once again Pyro, you feel it is accurate to have an inverted F4u-1D climb at a sustained 4k/min at 130 IAS?  Sustained?

at some point.. the wing and lift calculations on the wing become totally innefective.  The wing is no longer generating lift as a wing... only as a plate.  Then it simply becomes an issue of how much force is generated by the volume of air slamming into the top of the wing (the plate in inverted flight) forcing it up.  The angle of the impact calculates into it too.  If you are saying that the force needed to do this is sustainable at 130 ias with a 4k/min climb rate.. I'd really like to see YOUR numbers on that.

AKDejaVu

[AKDejaVu]

A side note to what I said above...

Inverted and normal flight in AH are nowhere near the same.  The maneuvers you are capable of in normal flight (positive G) are not repeatable (at the extreme) in negative G flight.  There is a difference.  Anyone that says otherwise hasn't flown recently.

My question simply revolves around how accurately inverted flight is modeled.

Given certain sets of numbers, I do not know that it is possible to adequately model inverted flight.  It would revolve around re-shaping algorithims in certain situations taking completely different factors into account.  Basically... airfoil simulation computing type of calculations.  Dunno if our systems have the processors to handle that just yet.

I will accept that its the best HTC can do right now... I just can't relly accept that its 100% accurate... but then show me the sim where it is?

AKDejaVu

[CptTrips]

>AKWabbit Stop the bs

Well Danish, if you don't think there are people like Spitboy, Macboy, Gadfly, etc, etc that come to this bbs with "other"  agendas then you are an idiot.

These aren't the only people who question the FM.  We have plenty right here.  A lot of the time they turn out to be right.  But a lot of it is idiots spouting off about how it doesn't "feel" right to them.  Most of the time this base of their experiences in other sims like FA, AW, Aces of the Pacific and such that in no way came be used as a useful comparision here.  More people around here could do worse than take a page out of Well's book.

Concerns about the FM are best expressed with well reason arguments backed up by careful testing, historical test data, or reasonable math are much more valuable to Pyro than random gut feelings.  If you don't think its better to back your gut "Feelings" with some kind of rational argument, and hopefully data, then you're an idiot.  Numbers can be checked and verified.  Opinions are like...well you get the point.  Or actually you probably still don't.

 
Regards,
Wab


BTW, I wasn't implying that Daft was one with a "hidden" agenda.  Although he does seem to have an unnatural fixation on inverted flight.  



[This message has been edited by AKWabbit (edited 09-21-2000).]

[Pyro]

Deja - it looks like you have some misconceptions about this.  An airfoil operates under the same principles whether it's inverted or not.  The difference betwen a cambered airfoil and a symmetrical one is that zero lift occurs at a negative AOA and max AoA and lift coefficient are lower than on the positive side.  

Climb is not a factor of lift, it's a factor of power.  In a steady climb, lift=weight.  At the same climb speed, the lift coefficient required will be the same whether inverted or normal.  More AoA will be required to achieve that lift co while inverted but that won't affect induced drag because induced drag is proportional to the square of the lift co, not the aoa.

So the induced drag won't change but there is a variation in parasite drag with AOA.  However, in the climbing condition parasitic drag component can be very small compared the THP available.  So even if there was a large change in the parasitic drag it doesn't necessarily produce much change in your climb rate.  



------------------
Doug "Pyro" Balmos
HiTech Creations

[danish]

AKWabbit
U implied daff has hidden agendas.
I said bs.

danish

[CptTrips]

>U implied daff has hidden agendas.
>I said bs.

Ahh so thats the hair that got up your ass.

I misspoke.  I wasn't talking about Daff.  I was reffering more to other FM critisism in the past.  Not necessarily in this thread.

I stand by my original point however that opinions are more valuable when supported by reason and evidence instead of mere conviction.


Regards,
Wab




[This message has been edited by AKWabbit (edited 09-21-2000).]

[AKDejaVu]

I am aware of how a wing works.  I am also aware that transfering the lift is not just a matter of increasing AoA.  It is, but there is more to consider.  The wing is no longer effecient in that the top of the wing is now significantly shorter than the bottom.  To change this, the AoA has to be adjusted drastically just for level flight at low speed.. not as much.. but still significantly at higher speeds.

Is it safe to say that the wing is less efficient inverted?  Wouldn't a higher stall speed be a by-product?  And in the process of stalling (nose going down) the initial added weight of the lift is going to make the plane nose down even more to gain speed?

I can porpuse between 400ft/min and 4k/min in a p38 inverted max climb.  It still accelerates inverted at 110 ias without losing altitude.. climbing up to 130 (4k/min) and then starts decreasing climb rate again.  Never does it dip below zero.

Once again, I'm not saying its way off or not modeled at all.  But if you think it is correct, I'll have to disagree with you.

AKDejaVu

[Daff]

Sorry, Pyro, I dont do maths..but I do fly a plane inverted from time to time. (In the moment only a couple of times a year, but that'll change soon)...a typical asymmetrical wing usually have a stallspeed 50% higher inverted than upright. (Check the pilots notes on a Yak52, Bulldog and T-67  for starters).
Also..if wings are that effective inverted, why bother with the fancy design?

Daff

------------------
CO, 56th Fighter Group
"This is Yardstick. Follow me"

[dudedog]

I fly R/C aerobatic machines and I'm quite familiar with aerodynamic theory. When flying a machine with a fully symetrical airfoil the performance is almost totally unchanged, and with a well aligned/balanced plane, hands-off inverted is quite possible. It is my understanding that most fighter airfoils are semi-symetrical, some almost full symetrical. Thusly, while flying inverted the only factors affecting the performance would be the incedence of the wing and stab and the airfoil. While I agree that the performance should differ a bit, unless you have specific data pertaining to the airfoil and incidence of the wing of the plane in question, please reserve your judgements untill backed up by real data. Unless you've flown a fighter inverted, or seen test data of such, you have nothing to compare it to other than your assumptions. I would really like to see more solid data when people question the FM. Otherwise it's purely subjective.

[AKDejaVu]

With asymetrical wings, you are implying that one side of the wing is in effect longer than the other.  That is how the lift is generated.

When you invert the asymetrical wing, in order to generate the lift, you need to make the top longer than the bottom.  But now, you have to make the the shorter side of the wing longer.  In effect, you lessen the area providing lift requiring an increase in the airflow required to generate equivilant lift.

and for you Dudedog.. we can question whatever we want.  Thankyou.

If I decide to criticize however... I'd better have some numbers.  I don't know where to begin solving the problem and I wouldn't have the knowledge to start talking down to HTC in regards to it.  They have generated a better flight model than I ever dreamed possible.  However, I will question anyone that thinks its perfect.

AKDejaVu

[dudedog]

StSanta, I meant no offence, I actually agree that the FM doesn't match my "assumptions" on how WWII aircraft would fly inverted either. But then I don't know what airfoils they use, nor have I ever seen inverted flight performance data.

[wells]

A typical airfoil, the NACA 230xx series as used on many WW2 fighters, such as P-38, F6f, F4f, F4u, Fw-190 has a negative Clmax that is about 80% of the positive Clmax.  The stall speed inverted would be the inverse square root factor, or close to 12% higher.  That's a 2% cambered airfoil.  The zero-lift angle is about -1 degree, so it would be really difficult to tell this airfoil as being non-symmetrical by just looking at it.  Going to a 4% cambered airfoil, it gets a bit worse...

The negative Clmax in the case of the NACA 4412 is 42% that of the positive and inverted stall speed would be 55% higher in that case.  That is the tip airfoil on the T-6 and P-38.

The thicker the airfoil for a given camber, the more symmetrical it's behaviour, so the thick root sections on the Typhoon and F4u would be as close to symmetrical as you would get, without actually being symmetrical airfoils.

[This message has been edited by wells (edited 09-21-2000).]

[AKDejaVu]

How about figuring this out Wells..

At a constant speed.. lets say 200 IAS, how much less lift is generated? Given that figure, and the angle the plane is climbing at... you should be able to calculate added wieght to the equation.

AKDejaVu