Yf-19 wings when swept back.

[one_one]

This has probably been asked befor or discussed in annother post but I couldn't find info on it. The YF-19 has forward swerpt wings but can also reverse this and be swept all the way back, I think this is only seen once in the anime. Anyway what is the reason, advantage it can do this, Does this allow it to go at maximum speed or something? What is the reasons and advantages and disadvantages for this?

[Angel's Fury]

Hopefully David can answer your question. He's the aircraft guru here.

Edited March 24, 2004 by Angel's Fury

[Yohsho]

I thought the purpose for the Yf-19 being able to sweep back its wings was part of the transformation process. Other than that I have now clue.

[Nani?!]

The real world problem with forward swept wings is that it hinders high speed maneuvers. The resistance it has against the wind is too much for the wings... They make a jet highly manueverable but hinders how fast the speed at which those manuevers can be made in. (this is what I read)

Given this, I suppose the 19 is made of stronger materials than what is currently being used on jets. Apart from the scene in the Plus series where the 19 folds in space (where there is no wind resistance), I would think the 19's wings fold back when it flys top speed in the earth's or eden's atmosphere.

Edited March 24, 2004 by Nani?!

[imode]

Or when it wants to look like a VF-11

[the white drew carey]

I'm only guessing here, but I'm assuming it's for high speed.

If you look at the shape of the fuselage around where the wings connect, you'll see that when they are swept back it makes a very long lifting surface, just not very wide.

This will reduce drag while still providing enough lift to keep airborne.

I may be stupid, though. Maybe we should wait till David shows up.

[Angel's Fury]

I wonder what's keeping David?

[mk16]

Well having flown this plane in xplane. i can say that with the wing completely swept back the plane can still generate lift(im not saying that the simulation is completely accurate,,but eh) and fly for a pretty long time with the engines at idle...well after a few minutes at full power.

My real comment is that that its impossible for the plane to really sweep the wings back like that. Theres no room for that third of the wing behind the wings axes, to basically go around and sweepback. It would cut across the engine and all the arm mechanism and the mechas "shoulder" part. yep impossible. well maibe sweep even more foward yeah with some modification.

[KingNor]

Well having flown this plane in xplane. i can say that with the wing completely swept back the plane can still generate lift(im not saying that the simulation is completely accurate,,but eh) and fly for a pretty long time with the engines at idle...well after a few minutes at full power.

My real comment is that that its impossible for the plane to really sweep the wings back like that. Theres no room for that third of the wing behind the wings axes, to basically go around and sweepback. It would cut across the engine and all the arm mechanism and the mechas "shoulder" part. yep impossible. well maibe sweep even more foward yeah with some modification.

?

are you saying that according to a simulator, the yf-19 is actually flyable?

for something that's designed soley on looks, thats pretty impressive.

[ewilen]

"If it looks right, it'll fly right".

Even more true when you have fly by wire.

[rdenham]

Although the yf-19’s rearward swept wing position may have some aerodynamic function it would also help to conserve space in much the same way as the F-14’s oversweep wing position of 75 degrees.

[Macrosso]

theres a secret jet to unlock in ace combat 04 that is like the yf19. dont know what it is called. so it is possible

[one_klump]

Yeah, I remember flying the YF-19 in X-plane, it was so powerful, you really could reach atmospheric service ceiling in 48 seconds

I also had the VF-1 and the VF-4.

The VF-1 was tons of fun to fly, thrust vectoring would do all the work. However, the VF-4 was a different matter, it handled like a house with little tiny wings.

[Noyhauser]

You can see it best in Digital Mission VFX-2... where the sweep gives it a wicked looking quality.

They are swept back for high speeds in atmosphere... which is the only place where it is useful. Forward Swept wings generate a lot of drag because the air is forced towards the body and over more wing surface which equals more resistance. It also creates more of a surface that has to break undisturbed air in front of an aircraft.(I can't remember what its called) A forward swept winged fighter must break undisturbed air across three points (two wing tips and its nose) FSW has other advantages like greater transsonic control and at high alpha, but it slows down fighters considerably. Sweeping backwards (like in a F-14 and in this case) forces airflow outwards and away from the body which generates far less drag. Its airflow's main break point is the nose, and the shockwaves move outwards from the body.

Just look at it straight on, with Forward swept the 19's forward profile is probably 20% more when they are out, and when they are blended in, thats at least 20% less forward profile to drive through the air. At high speed it doesn't need its wings because it would gain enough lift from its body, and you don't need that much of a control surface to control the plane when there is so much air going over the control surfaces. Moreover roll control can be accomplised through the YF-19's 1 dimentional thrust vectoring system(up and down feet)

However in space the 19 would probably always have its wings in forward swept mode because there is no drag to worry about, and it give the 19 better roll characteristics having the wings wider from the centerline (because there are verniers in the tips of the wings.)

Edited March 25, 2004 by Noyhauser

[ewilen]

rdenham, that's a beautiful picture. (I'm referring to the F-14, not your avatar )Great reference to see what "realistic" panel lining should hope to achieve.

[mk16]

Well having flown this plane in xplane. i can say that with the wing completely swept back the plane can still generate lift(im not saying that the simulation is completely accurate,,but eh) and fly for a pretty long time with the engines at idle...well after a few minutes at full power.

My real comment is that that its impossible for the plane to really sweep the wings back like that. Theres no room for that third of the wing behind the wings axes, to basically go around and sweepback. It would cut across the engine and all the arm mechanism and the mechas "shoulder" part. yep impossible. well maibe sweep even more foward yeah with some modification.

?

are you saying that according to a simulator, the yf-19 is actually flyable?

for something that's designed soley on looks, thats pretty impressive.

Yeah pretty much according to the sim you can fly it. But its pretty impossible at max throttle since you'd be unconscious within seconds. And its very maneuverable (hmm has a hight roll rate) at high speeds like its been said. With the wings swept back the plane is less maneuverable at high speeds(which is actually a good thing) and it can take off in a zinch, 1 seconds acceleration and you're off.

http://homepage.mac.com/bgillis/gallery.html

[KingNor]

what simulator is this?

is it readily available?

[Boxer]

The wings might fold for storage, like the VF-1's wings and tail fins fold for easier storage.

If it's worth anything, the YF-21's wings fold down for some reason.

[Skull Leader]

they SO need to wash that F-14, it looks damn near disgraceful.....

Yeah, I'm kinda interested in this X-plane simulator and I've never heard of it.... any info?

[Greyryder]

X-Plane website.

Interesting sims in that it actually calculates the flight dynamics, instaed of using a preset data file. I've got an older version of it.

[mk16]

Well yeah sure its available.

http://www.x-plane.com/ Main site,

you can download a demo from here. Its not time limited in the sense that it stops working after 30 days but...it works for 5 minutes before it turns off all user inputs(keyboard ,mouse,pads) then the plane is on its own(you can still fly it via autopilot)

This is a really good sim..you can actually train for an Airline Transport Certificate(given that you own a Full Motion Sim and pay an instructor) ..it has the best flight model around FS does not match it.

http://www.x-plane.org/

This is the best support site there is for the sim.(Macross world of Xplane ) People there are nice and allways helpfull. and they have tons of addons lots.

Edited March 25, 2004 by mk16

[VF19]

someone put it on kazaa or a bittorrent!

[Noyhauser]

If it's worth anything, the YF-21's wings fold down for some reason.

thats to ride the shockwave the plane's nose, intakes and forward stabilisers makes... the XB-71 did this as well.

[Akilae]

Well yeah sure its available.

http://www.x-plane.com/ Main site,

you can download a demo from here. Its not time limited in the sense that it stops working after 30 days but...it works for 5 minutes before it turns off all user inputs(keyboard ,mouse,pads) then the plane is on its own(you can still fly it via autopilot)

This is a really good sim..you can actually train for an Airline Transport Certificate(given that you own a Full Motion Sim and pay an instructor) ..it has the best flight model around FS does not match it.

http://www.x-plane.org/

This is the best support site there is for the sim.(Macross world of Xplane ) People there are nice and allways helpfull. and they have tons of addons lots.

I see a lot of airliners and whatnot... is this a sim in the sense of MS Flight Simulator, ie flying a 747, Cessna, etc..

Or could it also be used for combat flight sim? Would be interesting to see how the Supernova Project might have gone given similar piloting experience and controls...

[David Hingtgen]

A. I usually post LATE you know. And I've got a weird schedule for the next few weeks.

B. On something this important/complex, I usually like to do a quick review.

Ok, let's go on one of my fave topics. (quick note: wave drag=drag created by the formation of a shockwave, as in when you go trans/supersonic)

Noyhauser--your first paragraph strikes me as pretty wrong regarding FSW drag. Sorry, please correct me if I'm wrong. Also sorry if I come off negatively. I think you're mixing the nose's bow wave (and wave drag) with parasitic drag or something. (I have no degree, I just read a lot--I could be wrong) Forward-swept wings (generally, assuming similar characteristics) have less drag at transonic and supersonic speed than aft-swept. It was one of the design goals of the X-29. The spanwise flow (inboard on FSW) is irrelevant to wave drag, for the airflow effectively ignores the sweep (it doesn't travel right along with leading edge), it goes straight across the wing at a right angle to the leading edge (or at least it's only accelerated in that direction) ---that is the basic inherent property of sweep. If it wasn't, sweep would be nigh-pointless, as increasing sweep increases the structural length of a wing, increasing drag. It's only because sweeping it decreases the wave drag more than it increases the parasitic (skin) drag, that we do it.

This shows it pretty well:

http://142.26.194.131/aerodynamics1/High-S...phics/Sweep.GIF

Only that vector component of the air is accelerated, leading edge to trailing edge, not along the leading edge. You could have wings a mile long, but if their chord is only 20 feet, then the air only cares about the 20 feet.

Sweep basically "breaks up" the airflow into its component vectors.

http://www.desktopaero.com/appliedaero/pot...es/image446.gif

Thus, we only deal with the U1 vector, not U(infinity). (in the pic) Note angle A--sweep angle. For almost anything involving mach/sweep, etc, you use Cosine A. (Actually, 1/CosA if you want the new critical Mach number)

:::yeesh I'm tired::: Actually, this is more of a general supersonic drag theory question than FSW question, for as I mentioned above, it's simply Cosine A. And it doesn't care which direction. 45 degrees forward and 45 degrees back will have the exact same effect regarding drag, since it's the cosine of 45. (Asides from the minor minor differences FSW and ASW have----it's really close, the only reason it's mentioned a lot is because airlines would kill for 1% less drag for fuel savings).

Anyways---drag (parasitic) of FSW and ASW (aft-swept, AKA "normal" sweep) wings is really really close, but FSW is slightly better. Both ASW and FSW have the air move across a greater distance than a simple straight wing--which direction doesn't matter for drag, only for how it flies. (Maneuverability, lift, etc).

We're not talking manueverability here for the YF-19 (otherwise this'd be a LONG post), so we can just talk supersonic flight/drag etc.

(sorry for this being written disorderly like this, I've had a rough 24 hours--I'll edit/followup/etc later--everybody be sure to ask what you want clarified)

So---IMHO the YF-19's aft-sweep at high-speed is pretty pointless/impossible. Asides from the whole "it won't fit" problem, you'll also encounter the airflow going sideways across the airfoil. If it goes from -45 to 45, then you'll have the air going exactly across the airfoil sideways. And that lift is 0. If you put a 747 on the runway, and get a 200mph wind going from the side, it's not going to fly. You can't twist the air 90 degrees and expect lift. Heck, the F-14 only changes it 40 degrees betweeen min and max and loses most of the wing's lift. (60% loss off the top of my head--which is why it relies more on fuselage lift at high speed). However as Noyhauser brought up, the YF-19 relies (like many planes) on body lift at that point. It'd work if the YF-19's aerodynamic enough for it to rely 100% on body lift. (The wing roots are its only chance to develop enough lift, YF-19's fuselage is so not a lifting body, unlike an F-14)

Now, as for drag----well, when you go REALLY fast, sweep becomes pretty pointless actually. Sweep only increases the critical mach factor (the point at which you form a shockwave on the airfoil). However, as I mentioned---that decreases wave drag, not parasitic drag. Also, the more you do this, the less lift you have. So you start having to go to delta wings, bigger wings, etc. Eventually you're going to be flying a very skinny, very heavy triangle. (Like a Concorde, but even more so). The limit is basically Mach 3.5 for a practical plane, well under what YF-19's do. (Not that any valk flies below what it SHOULD based on sweep, but the YF-19 REALLY goes too fast).

At really high speeds, (Mach 5, like YF-19's go), you actually want no sweep, as the parasitic drag from additional structure due to sweep outweighs the decrease in wave drag. Look at the X-15---straight wings. Or the F-104---over Mach 2, nice straight wings. Having small wings decreases the drag, and being straight they produce lots of lift, so you CAN have small wings and not fall out of the sky. ::looks for graph::

Big important point Sweep is so you can use a normal (subsonic) airfoil in a supersonic environment. And it's only useful up to a point. Beyond that, you want a supersonic airfoil, which doesn't need sweep, because it's designed for it. But it's really bad for subsonic situations (like takeoff and landing).

Ok, I think that's it for tonight. I'm sure I've put a major error in there somewhere. This is like the "super question" for FSW, since it pretty much combines normal sweep, forward-sweep, Mach number, both methods of achieving supersonic drag reduction, and just about everything else.

Honestly, to fully explain it, I need to do a full "Mach and shockwaves" post, and "shockwaves and drag" post, and a "drag/shock/sweep" post. Plus a "forward vs aft sweep" post. I'll check here again as early as I can tomorrow. 3PM central at the latest hopefully.

Quick (hopefully) summary:

1. Drag-wise, FSW and ASW are really close, slight advantage to FSW, advantage greater at high-alpha. (Can't talk planes without mentioning alpha, especially not FSW planes).

2. The point of sweeping wings (in either direction) is to allow them to use normal airfoils (which are great for low speed and subsonic handling) in supersonic environments as well. But they have a practical limit. They're pointless for Mach 4, 5, 6, etc.

3. You can't mix FSW and ASW on the same plane, as the airfoils would become utterly ineffective. But that assumes you're only using the wings to fly, which many high-speed planes don't. YF-19 could use body-lift. (We'll assume it does, otherwise it couldn't fly at all in high-speed mode).

4. THUS: If the YF-19's body itself, or just the non-sweeping wing-roots had a supersonic airfoil, they would work quite well at ultra-high-speed, since the wings would be worthless, but they'd be in their element. (Though since the YF-19's wingroots are highly swept, they could use a subsonic airfoil--depends on exactly how much lift the wings make)

Edited March 25, 2004 by David Hingtgen

[David Hingtgen]

The main reason for the XB-70's folding tips was for yaw stability. The bigger they made the tips (by moving the hinge location), the smaller they could make the v.stabs. It was that or ventral fins, which'd add drag. The folding tips DID help with the shockwave-riding, but not much. They simply increased the effect. (more like "made sure it stayed under the wing")

Also, the shockwave it rode was just the one from the intake. The whole theory requires the shockwave to remain below the wing. The nose and canards did of course make shockwaves at high speed, but they were just like any other shockwave. The XB-70, for the wave-riding to work, required a specifically shaped and located shock, thus the big giant intake/engine box. (Technically it's actually more like "boosting the pressure from the wing's shockwave and using that" but everyone calls it wave-riding) The wing makes a shockwave, and like all waves increases the pressure--but with the addition of the intake under the wing, you get even MORE pressure under the wing and thus more lift--and for little or no additional drag because the wave is trapped under the wing) You'll note most fast planes have nice smooth/curved bellies under the wing--SR-71, Concorde, etc. But the XB-70 stuck that big huge intake box below right behind where the shockwave would form, and the shockwave had nowhere to go so it increased the pressure.

[J A Dare]

3.  You can't mix FSW and ASW on the same plane, as the airfoils would become utterly ineffective.  But that assumes you're only using the wings to fly, which many high-speed planes don't.  YF-19 could use body-lift.

4.  THUS:  If the YF-19's body itself, or just the non-sweeping wing-roots had a supersonic airfoil, they would work quite well at ultra-high-speed, since the wings would be worthless,  but they'd be in their element.

Looking at the image Angel's Fury posted, I too was thinking sweeping the wings aft was for "lifting body" flight as demonstrated by the X-24.

http://www.dfrc.nasa.gov/gallery/Photo/X-24/index.html

But why? Lifting bodies don't really "fly", more like "floating" decends. This principle was used in designing the Crew Return Vehicle (CRV) X-38.

http://www.dfrc.nasa.gov/gallery/Photo/X-38/index.html

My guess for the full aft sweep is for storage purposes.

[mk16]

I see a lot of airliners and whatnot... is this a sim in the sense of MS Flight Simulator, ie flying a 747, Cessna, etc..

Or could it also be used for combat flight sim? Would be interesting to see how the Supernova Project might have gone given similar piloting experience and controls...

Its a full sim you can fly military planes,xplanes, commercial, general, helicopters, hmm blimps , space shuttle, cars, boats, rockets, fly on mars, heh you could even make the macross if you wanted.

Well all planes can have weapons in the sim, bombs missiles, guns, the only catch is that they cause no damage. Nothing blows up...they would have.. but after 911 and the Iraq war the programers, Austin is the main person behind all this, had a change of heart. But yeah you can shoot missiles,drop bomb, guns ECT. But theres no damage. there are some forum guys working on a plugin that could enable you to dog fight and fake "shoot down" other planes over the net. Its all pretty much coming eventually. Maybe even before Version 8, you can get free upgrades till the next version, were on version 7.3.

[Wicked Ace]

A.  I usually post LATE you know.  And I've got a weird schedule for the next few weeks.

Thanks, for taking the time to explain, in detail; there are those of us who really appreciate knowledgeable input on science fiction fantasy (i.e. could this really work in real life?).

Edited March 25, 2004 by Wicked Ace

[Anubis]

I am always wowed at how much detail you write up for these kinds of threads. Thanks for the info as usual, DH.

[Angel's Fury]

I always enjoyed your insights David! My favorite is your explaination of the FSW concept. Too bad I can't dig it out from the old forum. This is kind of off topic, so if the YF-19 fusalage isn't a lifting body like the F-14, does the canards serve any purpose at this point? What do canards do? Is there wrong/right way on how the canards are supposed to be positioned? Care to explain why the canards on the SV-51 are positioned the way they are in comparison to the YF-19?

SV-51

YF-19

Edited March 25, 2004 by Angel's Fury

[Druna Skass]

theres a secret jet to unlock in ace combat 04 that is like the yf19. dont know what it is called. so it is possible

The X-02, the wings on it aren't the same as the 19's, since they fold into the main part of the wing instead of sweeping back.

I think that was just a concept design made just for that game...

Edited March 25, 2004 by Druna Skass

[KingNor]

But why? Lifting bodies don't really "fly", more like "floating" decends. This principle was used in designing the Crew Return Vehicle (CRV) X-38.

actually they can fly. as in. go up and down and such.

the lifting body for that shuttle thing simply was trying to get astronauts to the ground so it doesn't need to fly alot.

back in the 60's and 70's the US did create a few planes that flew with the lifting body design. they were unstable i think so they didn't keep them.

so a lifting body CAN fly, you just dont' see them much.

[KingNor]

they SO need to wash that F-14, it looks damn near disgraceful.....

Yeah, I'm kinda interested in this X-plane simulator and I've never heard of it.... any info?

i thought the f-14 looked kinda neat like that.

i like the texture in contrast with the polished canopy. makes the jet look ancient.

[David Hingtgen]

Any low-vis Tomcat looks just like that pic. Sometimes nicer, sometimes worse. It's simple--corrosion control/prevention. Any little spot that looks less than perfect, gets sanded/primed/painted right away at sea. And they only paint the exact little spot, not the whole panel, so it looks really patchy pretty soon. (Crews would like to do a whole panel at a time, it'd make the planes look a lot better, but the Navy says no) And paint batches don't match anyway. And sometimes you're out of Dark Ghost Gray and need to use Light Ghost Grey.

AC4's X-02: It's a YF-23 with switchblade wings embedded in the leading edges. (And new engines, ventral fins, folding stabs). But it's 80% YF-23, much like AC2's XFA-27 was mainly an F-14.

Angel's Fury: a quick explanation of canards is that they are basically the opposite of horiz. stabs. Unless you're an F-16 or X-29 or anything else purposely realyl unstable, a plane's center of lift is aft of its center of gravity. That is basic stability---if lift is forward of center of gravity, you're unstable. ::tries to find pic::

Ok, more extra stuff than I wanted, but it shows it well:

Big black vertical line (W): center of lift from wings. Yellow dot: center of gravity. Lift pulls up, gravity pulls down. Imagine if you attached strings to the center of lift and center of gravity, and pulled in opposite directions (down from gravity, and up from lift). Since lift is aft of gravity, the plane will tip nose-down. Not good. Now look at the h. stabs---the big black line labled T. That's the force from the tail. It is small, but aft of the wings, and pulls down, thus righting the aircraft, thus level flight. That is how most planes fly. If a plane weighs 100,000lbs, you actually need like 120,000lbs of lift from the wings, since the tail will probably be pushing DOWN with 20,000lbs of force, to keep the plane level.

So---what's another way to keep the plane level? The exact opposite--a small tail pulling UP, AHEAD of the wings. Which would be canards. Generally seen as superior, since they add to the lift of the wings, rather than trying to oppose them from behind. Best example is takeoff--you're at the end of a runway, trying to get lift to get off the ground--then to pull up, you push DOWN with thousands of pounds of force on the tail----not the best way to get UP.

You can kind of think of it like this--to make a balanced force against gravity, you can have either a huge lifting force from the wings and a downforce from the tail, or a medium lift from the wings and a small lift from the canards. Tailplane downforce generally is more stable, but canards are lighter and quicker. Thus you see airliners with tailplanes, and many fighters with canards. You also see many modern fighters with tailplanes instead of canards--why? Well, some designers just don't like canards (this is why F-16's don't have them). Heck, it's the reason most don't have them. Also---it is easy to add a canard for additional stability/control, like you see on the X-29 or S-37 or the XB-70. It is however very easy to add a "bad" canard and have a really messed up plane if its the ONLY source of pitch stability. SAAB is certainly good at it, but many companies/designers are not experienced with it. Canard-only designs are AFAIK harder to design than tailplane/h.stab designs.

Finally---you're much more likely to see canards on a delta-winged plane. Look at XB-70, most modern European fighters, etc. It mainly has to do with how elevons work on delta-winged planes, and especially the "takeoff" situation I mentioned. Also, since delta-winged planes are generally quite stable in pitch anyway since they have such huge wings and a spread center of lift (unless you design it not to be), they usually use canards as a supplement, not the only source for pitch control. (Since it's usually the wing itself for pitch control----look at a Concorde---nothing but the wing).

So in summary a YF-19 would probably use its small canards simply as an additional source of pitch control, since it has thrust-vectoring like almost every other valk for its primary source of pitch stability/control. Canards (like most any control surface if you want) can also be used differentially for roll control, but the -19's are so small it's probably pointless. "Supplemental" canards are awesome to quickly pitch-up (the main move fighters do) because if you have a normal tailplane--that means you've got a downforce at one end of the plane, and an upforce at the other--and you will very quickly rotate the aircraft about its axis like that.