Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: Daff on August 04, 2000, 06:41:00 PM
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Will that be fixed in 1.04?.
Daff
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CO, 56th Fighter Group
"This is Yardstick. Follow me"
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Is it broken ?
(its a serious question)
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Broken..I guess you could say so..it's the same as "normal" lift and drag, ie the planes have symmetrical wings.
Daff
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CO, 56th Fighter Group
"This is Yardstick. Follow me"
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Yep I get the same rate of climb inverted or right side up. I haven't noticed symmetrical airfoils on the WW2 fighters I've had a chance to look at. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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The planes don't have symmetrical wings...not by a long shot. At least not in RL...
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Out of curiousity Daff... honest... why is this important to you? I just ask this because when you've mentioned this before, I've tried to pay attention to how that would affect my flying/fighting... and I think I must be looking at it wrong. Unless yer chasing a bandit that chooses to fly inverted the whole way (no extra drag) or you intend to pull some wild neg-G manuevers/evades (inverted lift) I cannot come up with a reason why this would be such a sore spot.
Help me out with this.
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Several reasons.
One is that it should be there, before any of the sims can call themselves "realistic".
(No, it isnt in WB either). It's basic stuff, really.
Two, it would stop several silly manuevers, like outside barrel rolls, bunts at low speed and lomcevak like manuvers because either it would cost too much E or they'd simply depart. (A typical inverted stall speed is about 50% higher inverted than upright). It would make the standard rolling 190 defense (yes other planes are also capable of that) pretty much useless. (I should mention that this problem is much worse in WB).
In short, it would force people to learn to fly more realisticly.
I know it's on the shortlist of things to fix in WB (Although I dont think that list is short at all (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)), but I've yet to hear Pyro/HT acknowledge it.
Daff
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CO, 56th Fighter Group
"This is Yardstick. Follow me"
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Yup, just as I figured... there's a whole damn flying envelope out there I wasn't aware of that concerns this inverted lift/drag thing. Now I gotta go back to flight school and figure out what a low speed bunt and a lomcevak are. Thanks a lot (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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Bunts...lomcevaks...makes me reach for my Excedrin....although a low speed bunt is one heck of a lot easier on the bod than a high speed one.
Lomcevak...sort of did that in a F-104 once...not on purpose of course. +8 to -3 G in about a second. I don't recommend it.
Speaking of the 104...it had a 'regular' unsymmetrical airfoil as well.
Andy
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The 104 had wings? I thought those were guidance fins?
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Daff is correct- it is important in a realistic flight model to get this right. You better believe a lot of the beeeeyoootiful rolls, loops, and assorted maneuvers would get much sloppier with asymmetrical airfoils. (Heck, even veteran R/C pilots know the difference in rolling a Clark Y vs. a fully symmetrical airfoil.)
In short, at slow speed rolls at low alt would cause that plane to dig a great big ditch- you would see a lot more altitude loss while inverted. (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
[This message has been edited by Kieren (edited 08-04-2000).]
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I'm sold.
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Doesn't Lomcevak mean "headache"? (Seriously)
Try this, Nash. Dive a 51 at about 10 degrees. When the speed builds, pull into a nice vertical zoom. When you get it lined out straight up, push full forward and left while holding right rudder. If you do it right the plane should tumble forward.
I haven't been able to get it down just right, but that is the basic idea (as I understand it).
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Tried it Kieren - thanks. It put me into a kind of messy barrel roll. Is this what should happen? These kinds of evasives are something I really *should* work on.
My philosophy when it comes to evasives up to now, basically, is that unless things are in such bad shape that ya need to go into scissors etc. and force an overshoot somehow... that you remain in an offensive mindset. ie, your still the attacker, you just have more catching up to do.
It always struck me as kind of defeatist to throw yer plane into wild out of plane type manuevers simply to throw off the enemy's gunnery. Like lost seconds that ya coulda spent bettering yer angles. However, my stats will bear out the fact that this is probably not the right way to look at a fight.
This is now way off topic...I shoulda put this in the Training forum... But it sure has been an enlightening thread for me. Thanks.
Back to yer regularly scheduled FM gripes (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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Andy Bush wrote:
The planes don't have symmetrical wings...not by a long shot. At least not in RL...
Andy, how far off are they? In, say, an F16?
Wouldn't asymetrical wings overload the super 8086's the Viper use for its FBW? (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
Joking aside, this should affect flight performance considerably.
I understand that wings flex under g loading and so forth, adn that modern FBW systems can compensate for uneven loads and so forth, but still?
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StSanta
JG54 "Grünherz"
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Nash-
It actually should be more of a snap roll in the forward direction- it should be violent (hence "Lomcevak-headache"). I wouldn't really consider this as a defensive maneuver at all. It's more of an air show trick.
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Daff has brought up a great point.
Plus, I don't think Daff is trying to bust balls here, I honestly believe he is asking this to help suggest improvements in AH's flight model.
Plus alot of the defensive moves we see now, just aren't really that desirable to do if the inverted lift and drag is modeled closer. The cost to do them outweighs the benefit, especially down low. Or up high you'd see alot more aircraft departing from controlled flight IMO.
Cobra
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Nash, the thing is that you can "abuse" the current inverted lift/drag to gain angles.
You got a con on your 6, you roll inverted and start pushing up. The con starts pulling his nose up (he's still upright) and as he gets close to get guns on you, you pull back on the stick. There's no way he can follow that. He wont have enough elevator authority to push nose low (or will red out doing so) and if he rolls inverted, it will take time.
You, OTOH, have just gained a significant amount of angles, possibly an overshoot and it hasnt cost you the E it ought to have cost you.
Daff
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CO, 56th Fighter Group
"This is Yardstick. Follow me"
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Hmm....
<evil grin>
That's an interesting tidbit of information Daff.
Very... tempting. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
<taps fingers on the desktop...ponders>
The lord's prayer sayeth:
"And lead us not into temptation"...
However... the very next line clearly states:
"But deliver us from evil"
Hhm....
(http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
[This message has been edited by Nash (edited 08-05-2000).]
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You mean you havent seen anyone use that move???.
Daff
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CO, 56th Fighter Group
"This is Yardstick. Follow me"
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Actually? No... But uhm... I 'spect I'll be seein' more of it now.
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I've tried to, to be honest. But before I could yank back on the stick to do the break downwards I was dead. But I never knew about the issue being talked about here. I always thought it would be easier to roll inverted, go upwards and then yank back.
-Westy
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One of the changes we're making a change to will effect this, but I have one question for you. Why do you believe a plane cannot climb well from an inverted position? If you can express this mathematically, even better. I ask because it sounds like you're looking for a huge difference, and I tend to doubt there will be one, although I haven't checked.
BTW, this is outside of stuff like oil starvation.
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Doug "Pyro" Balmos
HiTech Creations
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I believe Bernoulli got a few things that hints in that direction.
Since the wing is shaped to give the fastest airflow (more lift) over the top of the wing, you need to increase the AoA to "shift" the leading edge when flying inverted (in order to get the faster airflow over the bottom on the wing), ie more drag, lower climbspeed, higher stallspeed.
A tad surprised by that response, to be honest.
Daff
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CO, 56th Fighter Group
"This is Yardstick. Follow me"
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I remember a piece in Clarence Emil Andersons book where he described a shooting chase with a 109 and the 109 went inverted in a climb. Anderson commented how odd that was to see as flying a plane like that "required a tremendous amount of effort".
The 109 subsequently went nose down and crashed without the pilot escaping.
FWIW, I dont find any advantage in inverted flight. However, it is an act of engineering vs physics and should be in any FM if at all possible.
I once flew an entire sortie up-side down.
Its no fun.
Yeager
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I have a question Daff, what about angle of incidence remember that, with that in mind and possiblity the advent of laminar flow wings ya know the wings that are suppose to be the same on top as on bottom. The point being that not any of the a/c in HT have the same angle of incidence and some are more or less laminar the others, which would explain why some aircraft with the assist with copious amounts of power can climb inverted and others can't that being in the real world which does not seem to apply in HT. Please don't misunderstand me I love HT if not for the aircraft but for all the friends i have made playing which is the most important part of the game to me. Any who the angle of incidence would also play a large part of the aoa with is the difference between the angle of incidence and the cord line of the wing...some basic flight school junk.., So in the end you are correct Daff these planes should not be doing what they are doing, and if we had to physically take the damands of the g forces both neg and poss you would see less and less of this stuff being performed, (specially after and heavy night out on the town or some real greasy food... thats my 2 cents worth..
thanks for the ear... (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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HI, again sorry about AOA, that is the difference between the cordline of the wing and relative wind... pls forgive my minor oversite. and I amy not even touching dihedral..
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...throw in the thrust line, incidence of wing and stab, airfoil selection, dihedral... it is more complicated than "the airfoil is not symmetrical". The one thing we can agree on is these aircraft were optimized to fly right-side-up. (http://bbs.hitechcreations.com/smf/Smileys/default/wink.gif)
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It's a given that more AOA will be required. The point I'm after is why you feel this would lead to a lot more drag. Keep in mind that this is not the same as comparing identical wings to each other at different AOA's.
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Doug "Pyro" Balmos
HiTech Creations
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The increased drag will probably be directly related to the increased AoA.
Increased AoA = increased downwash = increased drag.
Add to that, that the underside of the wing, even with the displacement of the leading edge (by increasing the AoA) will most likely be less effective in the lift departemnt than upright, you again need to increased the AoA to get the same amount of lift out of it, again increasing the drag.
Parasite drag could also be increased, as the leading edge is now more blunt than in upright, although this would depend on the design of the airfoil.
How much the angle of incidence would affect it, I guess it's more relevant in the stall department. (Outer wing would stall first).
Dihedral will definitly affect stability, but I dont know if there's other effects (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif).
I'm no aeronautical engineer, just a PPL with a keen interest in aerobatics.
Daff
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CO, 56th Fighter Group
"This is Yardstick. Follow me"
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Written out loud to all, not directed at anyone. (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
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Things I can see that would impact the ability to climb as well inverted as upright:[list=1]- Airfoil selection. With a semi-symmetrical airfoil the center of lift would be located in a different location, possibly affecting the AoA necessary for level flight. Inverted the airfoil would possibly generate less left even under optimum conditions due to the amount of curve applied to the lower surface. Again, a higher AoA would be needed to compensate for the decreased lift ability, increasing drag.
- Dihedral. Dihedral is the upward sweep of the wing that increases stability in the upright, normal flight regime. The high wing's lift vector is not pointed vertically up as much as the lower wing's lift vector, therefore the high wing tends to drop. While inverted, the reverse would be true. This would force more control input to maintain control, therefore more drag.
- Washout. Washout is the turning of the tips of aircraft down (AoA) a few degrees relative to the root of the wing- the purpose is to help maintain control at slower speeds (delaying the stall of the wingtips a few mph). Inverted, wingtip stall would occur faster.
- Thrust line. In many cases the thrust line of an aircraft will not be set at 0 degrees. The Hellcat had something like 2 degrees down thrust, so inverted that converts to 2 degree positive thrust.
- Angle of Attack (AoA). The position of the wings relative to the centerline is chosen with many factors in mind, but in our case it is important to know that if an aircraft carries 1 or 2 degrees positive AoA in upright flight it translates to 1 or 2 degrees negative AoA in inverted flight. This would increase drag over regular flight significantly. Don't forget the horizontal stab can have its AoA set too, and this must be figured in as well.[/list=a]
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In the end, inverted flight should probably be harder to maintain, show decreased performance, and generally feel unstable. Maybe someday I will take a "dream ride" and find out for myself- what do I know! (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
I eagerly await the holes that will be punched in this. (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
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http://www.hpcisp.com/~kieren/calendar/calendar.htm (http://www.hpcisp.com/~kieren/calendar/calendar.htm)
[This message has been edited by Kieren (edited 08-07-2000).]
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Originally posted by Daff:
The increased drag will probably be directly related to the increased AoA.
Increased AoA = increased downwash = increased drag.
This is what I was getting at by saying that you really have to make the comparisons as if it were two different airfoils. The part you said above about AOA is a general statement that is true for most discussions dealing with an individual wing at different AOA's. But the reality is that it's really based on Cl. Looking at this example, the plane weighs the same, has the same wing area and planform, and will require the same Cl whether inverted or not.
Example: 2 planes have the same weight, wing area, aspect ratio, etc. The only thing different are the shapes of the airfoils. Plane 1 has a lift co of 1.0 at 10 degrees AoA. Plane 2 needs 11 degrees of AoA to get a lift co of 1.0. Which plane has more induced drag?
Anyway, there are differences between an inverted and normal climb, I'm not trying to argue that. I just don't know that they will be that big of a deal when it comes to climb rate. But then, I don't even know how much difference in RoC it makes to have your gear down.
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Doug "Pyro" Balmos
HiTech Creations
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Is radial G modeled in AH?
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Well, I know that on a typical asymmetrical winged plane, the inverted stall speed is about 50% higher than upright. That, too me, indicates that lift is a fair bit lower and drag a fair bit higher.
You dont have an airfoil analyzer to get the general numbers for inverted lift and drag?
Daff
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CO, 56th Fighter Group
"This is Yardstick. Follow me"
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What a thread!!
Regarding laminar flow airfoils...they are usually cambered just like any other unsymmetrical airfoil (the P-51 had a unsymmetrical, but laminar, airfoil).
An inverted climb under 'normal' conditions would be an uncomfortable experience in a WW2 fighter. 'Normal' in this case means a sustained climb where the aircraft is at or near one G.
The unsymmetrical shape of the airfoil would tend to produce a lifting force off the 'top' of the wing regardless of the attitude of that wing. If that attitude is down, then that lifting force is also down...and would have to be offset by an equal and opposite force to keep the aircraft from going down.
In any aircraft, the pilot gets that equal and opposite force by pushing forward on the stick How much? He needs to see minus one G on the G meter.
The difference between a symmetrical and unsymmetrical airfoil aircraft is that the pilot in the unsymmetrical aircraft has to 'push forward harder' to get the needed angle of attack on the wing to obtain the minus one G. Generally speaking, the unsymmetrical aircraft will require a greater AOA than its counterpart. This AOA may or may not be attainable...or sustainable (the aircraft may 'stall' first).
Anyway, the real point is that I can see no reason for an inverted climb in RL...now if the sim programming gives a particular advantage under these conditions...well, that's a different story!
Andy
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"Anyway, the real point is that I can see no reason for an inverted climb in RL"
Why not?..it's fun! (http://bbs.hitechcreations.com/smf/Smileys/default/smile.gif)
Daff
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CO, 56th Fighter Group
"This is Yardstick. Follow me"