AVF Upgrade Candidates

[Seto Kaiba]

Thanks for clearing that up for m Seto. I think that the elimination of the canards probably had a lot to do with the increase in stability, though The wing design on the VF-19F/S would likely have the same issues as a tailless delta wing would it not? That would make it less than ideal for atmospheric operations, since it would have higher landing speeds, unless they somehow figured out how to make ele-flap-erons...

Probably not a huge concern for the VF-19F/S type, after all... that version of the Excalibur was optimized for usage in space.

[GuardianGrey]

Okay, Seto Kaiba, I see that I had a misunderstanding about the SWAG armor & engine output... Though still, WTF?

ECA was introduced into the continuum with Macross Zero. And the issue of not having full-time/powered SWAG armor is not resolved until 50 years later with either multiple engines, or an expensive system, is used?

What, were all the R&D techs chasing an idol's skirt or something?

(Isamu to Yang; "Well, her virginity would be hard to get.")

Same though, but only 20 years of development, on the IVCS/ISC system.

I believe the FAST/Super-part system is supposed to (usually) optimize VF for space, and I notice that the VF-25 does not (seem to) have verniers on the wings. So I wondered why they were not just folded back in/under the booster packs?

[Valkyrie Driver]

Probably not a huge concern for the VF-19F/S type, after all... that version of the Excalibur was optimized for usage in space.

But what about the one in the New Episode archives book? That's clearly in atmo...

[Valkyrie Driver]

So, here's a question that just came up in my mind, regarding control surfaces.

I know that most artwork has been shown with traditional control surfaces, but is it possible that some things were perhaps adopted along the way, like the YF-21's active wing surface? I also see no reason to believe that Aerodynamics wouldn't progress along the same lines of thought as they currently have, so something similar to the NASA X-53, might have occurred. Wing warping has worked since the early days of flight (the wright flyer and most other planes of similar design and construction used wing warping to turn), so is it possible that it made it's way into variable fighters at some point, to increase the aerodynamic efficiency of the fighters (as most, if not all, VF's lack horizontal stabs), the use of some mechanism outside of thrust vectoring to change pitch would be needed. Thrust vectoring can do amazing things but it's no substitute for aerodynamic surfaces inside a planetary atmosphere.

A recent conversation also led to this one, I was discussing the benefits of drones, and the drawbacks of high altitude flight, I assume that all VF's are radiation shielded to protect the pilot from cosmic radiation (what with the stratosphere and space providing no protection against that nuclear furnace 93 million miles away from us).

What say you?

[JB0]

A recent conversation also led to this one, I was discussing the benefits of drones, and the drawbacks of high altitude flight, I assume that all VF's are radiation shielded to protect the pilot from cosmic radiation (what with the stratosphere and space providing no protection against that nuclear furnace 93 million miles away from us).

What say you?

Yeah... whether it's documented or not, I'd totally assume some form of radiation shielding.

...

Unless they just wear lead-lined flight suits?

[Mr March]

Well, like all fiction, Macross too is limited by being a product of its era. With the exception of things like the YF-21's "composite material wing", it's not as if the Macross writers can predict the future of aerodynamic design. So often by default a long running sci-fi franchise may find some of it's creative assumptions outdated by reality in the decades since its initial conception. I don't think much has been said about wing control surfaces in Macross. Perhaps the Master File series embelishes upon those aspects of wing design with more detail?

I think Macross' nature as an anime to sell toys to kids also has an affect upon the fiction. Even after all this time, there still hasn't been a YF-21 that even bothered featuring parts-swapping to realize the composite material wing and few toys have even bothered featuring the traditional control surfaces. Doing crazy advanced stuff in fiction might be ultimately defeating since the toy manufacturers will never be able to implement those design features into a toy product?

[Seto Kaiba]

ECA was introduced into the continuum with Macross Zero. And the issue of not having full-time/powered SWAG armor is not resolved until 50 years later with either multiple engines, or an expensive system, is used?

What, were all the R&D techs chasing an idol's skirt or something?

Nah, it's just a technology that requires an incredible amount of energy to achieve the results it does, and has to contend with lots of other critical functions for the power it needs.

The armor on a VF is fairly thin stuff... and while the material itself is extraordinarily tough, the energy conversion armor is drawing an awful lot of power to beef up that material to levels that let it shrug off weapons fire orders of magnitude deadlier than what our modern armed forces have. The VF-0's energy conversion armor needed 90% of the battroid's generator output to beef its armor strength up to the level of a main battle tank.

Part of the problem is that while the thermonuclear reaction engines that VFs use to get around use the heat and plasma from the reaction to either heat intake air as propellant (in atmosphere) or use the reaction's plasma stream as propellant in space... which ultimately means that a LOT of potential power is lost generating thrust. So as technology advanced, generator output increased, but so too did engine thrust requirements and the number and severity of "accessory loads" on the power system thanks to more (and more powerful) sensor and stealth systems, integrated energy weapons, computers, communications systems, etc.

Barrier systems are also famously energy-thirsty devices, so that probably isn't helping matters any.

It wasn't until the VF-25's generation (the 5th?) that engine reactor output finally outpaced engine and accessory power demand to the point that light energy conversion armor could be employed around vital areas like the cockpit and engines in fighter mode. To fully utilize energy conversion armor in all modes, a fold wave system or fold dimension resonance system is necessary, which lets the YF-29 and YF-30 cheat up their generator outputs by pulling energy directly from super dimension space. Considering what is said/shown in Macross the Ride, the VF-27 probably needs at least 3 engines to produce enough surplus power to run its gun pod on top of everything else, so when the gun pod is not in use it can use the excess output for its stated ability to use its barriers and energy conversion armor to compensate for the friction heating of the airframe while flying above Mach 5 at around 10km.

I believe the FAST/Super-part system is supposed to (usually) optimize VF for space, and I notice that the VF-25 does not (seem to) have verniers on the wings. So I wondered why they were not just folded back in/under the booster packs?

Actually, both the CG model from the animation and the art in Variable Fighter Master File: VF-25 Messiah show verniers on the VF-25's wingtips. You can seem them quite clearly in this image.

Of course, there is another reason to leave the wings out with the Super Packs on... as seen in Master File, you can still use the 2 outer pylons on each wing for ordinance. (There's a really good picture of this on pages 076 and 077, which show VF-25's using their pylons for AMM-101 and RMS-7 missiles with their Super Packs attached.)

But what about the one in the New Episode archives book? That's clearly in atmo...

Just because it's optimized for space doesn't mean it can only be used there... they used VF-19F's in atmosphere during Operation Stargazer in the Macross 7 TV series.

I know that most artwork has been shown with traditional control surfaces, but is it possible that some things were perhaps adopted along the way, like the YF-21's active wing surface?

All told, the YF-21's active wing technology is described as being extremely difficult/complicated to control properly without using a cheat like a BDI system or implant technology, to the extent that a conventional FCS capable of controlling it is still WIP in 2058.

(This is part of the description of the VF-19ACTIVE "Nothung" from Macross the Ride.)

so is it possible that it made it's way into variable fighters at some point, to increase the aerodynamic efficiency of the fighters (as most, if not all, VF's lack horizontal stabs), the use of some mechanism outside of thrust vectoring to change pitch would be needed. Thrust vectoring can do amazing things but it's no substitute for aerodynamic surfaces inside a planetary atmosphere.

To a certain extent, they're using boundary layer control for this... and have been since the original VF-1... but the existing stabilizers (which are variable cant on many later designs) and thrust-vectoring carry a big part of this burden.

[Valkyrie Driver]

Well, like all fiction, Macross too is limited by being a product of its era. With the exception of things like the YF-21's "composite material wing", it's not as if the Macross writers can predict the future of aerodynamic design. So often by default a long running sci-fi franchise may find some of it's creative assumptions outdated by reality in the decades since its initial conception. I don't think much has been said about wing control surfaces in Macross. Perhaps the Master File series embelishes upon those aspects of wing design with more detail?

I think Macross' nature as an anime to sell toys to kids also has an affect upon the fiction. Even after all this time, there still hasn't been a YF-21 that even bothered featuring parts-swapping to realize the composite material wing and few toys have even bothered featuring the traditional control surfaces. Doing crazy advanced stuff in fiction might be ultimately defeating since the toy manufacturers will never be able to implement those design features into a toy product?

Right, I get where you're coming from here. I was thinking we could maybe apply that sort of thing retroactively as sort of apocryphal info. It doesn't really affect anything we see in the show, all it does is explain things aerodynamically and maybe help us explain things so that we have an easier time suspending our disbelief.

But what about the one in the New Episode archives book? That's clearly in atmo...

Just because it's optimized for space doesn't mean it can only be used there... they used VF-19F's in atmosphere during Operation Stargazer in the Macross 7 TV series.

So, here's a question that just came up in my mind, regarding control surfaces.

I know that most artwork has been shown with traditional control surfaces, but is it possible that some things were perhaps adopted along the way, like the YF-21's active wing surface?

All told, the YF-21's active wing technology is described as being extremely difficult/complicated to control properly without using a cheat like a BDI system or implant technology, to the extent that a conventional FCS capable of controlling it is still WIP in 2058.

(This is part of the description of the VF-19ACTIVE "Nothung" from Macross the Ride.)

so is it possible that it made it's way into variable fighters at some point, to increase the aerodynamic efficiency of the fighters (as most, if not all, VF's lack horizontal stabs), the use of some mechanism outside of thrust vectoring to change pitch would be needed. Thrust vectoring can do amazing things but it's no substitute for aerodynamic surfaces inside a planetary atmosphere.

To a certain extent, they're using boundary layer control for this... and have been since the original VF-1... but the existing stabilizers (which are variable cant on many later designs) and thrust-vectoring carry a big part of this burden.

1. Good point about the optimization not being specialization.

2. The BDI would make the active wing easier to control, as it is implemented on the YF-21, but the concept is still very similar to the X-53 test craft, and using an active aeroelastic wing on a conventional variable fighter could be done in a similar fashion to the X-53, and controlled by the active flight management system, to keep it stable.

3. I'm curious to know how you get the BLC, are they shunting high pressure bleed air over the wing at slow speeds to trick the wing into "thinking" it's flying (ala the F-4) or are they using some other technique (mechanical vortex generators would be counter productive for a high speed aircraft due to the parasite drag). That might slow your takeoff and landing speeds a bit, but it doesn't take the place of flaps.

[Seto Kaiba]

2. The BDI would make the active wing easier to control, as it is implemented on the YF-21, but the concept is still very similar to the X-53 test craft, and using an active aeroelastic wing on a conventional variable fighter could be done in a similar fashion to the X-53, and controlled by the active flight management system, to keep it stable.

Similar in the most basic sense... but what the YF-21 did is on a whole other level.

3. I'm curious to know how you get the BLC, are they shunting high pressure bleed air over the wing at slow speeds to trick the wing into "thinking" it's flying (ala the F-4) or are they using some other technique (mechanical vortex generators would be counter productive for a high speed aircraft due to the parasite drag). That might slow your takeoff and landing speeds a bit, but it doesn't take the place of flaps.

Well... actually, it's a little from Column A and a little from Column B there.

Several VFs (incl. VF-19 and VF-25) do use Vortex Flow Control for attitude control via negative pressure.¹

On the other hand, most VFs have Boundary Layer Control implementations... usually involving a sub-intake in the front fuselage just above the main intake... which is used for attitude control. It's an air suction system, and extends into the leading and trailing edges of the wings (and on the VF-25, apparently into the wing glove and as far back as the stabilizers).

1. See page 49 of Variable Fighter Master File: VF-19 Excalibur and page 30 of Variable Fighter Master File: VF-25 Messiah for helpful infographics and explanations.

[Mr March]

Right, I get where you're coming from here. I was thinking we could maybe apply that sort of thing retroactively as sort of apocryphal info. It doesn't really affect anything we see in the show, all it does is explain things aerodynamically and maybe help us explain things so that we have an easier time suspending our disbelief.

Retroactive apocrypha does happen in Macross, some appeared in the Macross Chronicle technical descriptions. So we could imagine it might happen. I think if you examine some of the transformation systems of the variable fighters, they would already feature a version of the aeroelastic wing concept in basic form, just by virtue of how their wing components are mounted and can shift mechanically. The YF-19 and VF-25 immediately come to mind as two such designs.

[Valkyrie Driver]

The AAW (Active Aeroelastic Wing) would give you a control surface that could function like a flying tail (the whole stab moves as the control surface rather than just having trailing edge surfaces) and would work like ailerons (only full surface movement) while still allowing you to have flaps on the inboard section of the wing (the part that doesn't move). This would allow for greater maneuverability, and when coupled with boundary layer control, would serve to allow for much lower landing speeds in atmo, which would also counter the ground effect that large area wing surfaces tend to generate.

I think it would be safe to assume that, given the level of technology we see in macross, this would be the case in many later generation fighters.

[Seto Kaiba]

I think it would be safe to assume that, given the level of technology we see in macross, this would be the case in many later generation fighters.

Personally, I'm not so sure... from Master File, the attempts to upgrade the VF-1 seem to be concerned with improving the wing rigidity and frequency response, and I'm not seeing anything like it mentioned in connection with any aircraft except the YF-21/VF-22 and VF-19ACTIVE. (Possibly it's because of the VF's other role as a ground warfare unit, where armor endurance is paramount.)

They seem to favor methods that alter the airflow over the airframe... like boundary layer control, vortex flow control, variable-cant stabilizers, etc.

[GuardianGrey]

I feel that they have that ability, though it's not shown in a VF, but a VB. Though I could be totally wrong.

The VB-6 has to convert a wing into a leg & back, which has to be no small feat do to the weight involved.

Getting that servo to be aerodynamic enough for flight would need a morphing surface system, I feel.

[Valkyrie Driver]

OT solves a lot of problems, you could have the wing surface rigid when you need it, yet elastic when you need it. Though most fighters seem to have enough trailing edge space for flaps and elevons.

[Seto Kaiba]

I feel that they have that ability, though it's not shown in a VF, but a VB. Though I could be totally wrong.

Nope... officially, the only aircraft in Macross which have been mentioned as having anything along those lines are the YF-21/VF-22 and VF-19ACTIVE. From everything I've been able to find on the X-53 program, it sounds like the same problem was solved using different methods on VFs... specifically, a more rigid wing courtesy of overtechnology materials, and drag manipulation using vortex flow and boundary layer control.

The VB-6 has to convert a wing into a leg & back, which has to be no small feat do to the weight involved.

Getting that servo to be aerodynamic enough for flight would need a morphing surface system, I feel.

Um... why would the actuator need to be aerodynamic? It's INSIDE the airframe in Bomber mode - when aerodynamics actually matter - and is only exposed for a couple seconds during transformation, tops.

OT solves a lot of problems, you could have the wing surface rigid when you need it, yet elastic when you need it. Though most fighters seem to have enough trailing edge space for flaps and elevons.

That's kind of the thing... I'm not really seeing the benefit of the active aeroelastic wing vs. what the VFs already have in terms of airflow manipulation and control surfaces.

[Valkyrie Driver]

It was just a thought, I wondered how exactly a VF without a horizontal stabilizer, and thus elevators, would change pitch in atmo, while maintaining the ability to roll, and being able to land at low speeds.

[JB0]

It was just a thought, I wondered how exactly a VF without a horizontal stabilizer, and thus elevators, would change pitch in atmo, while maintaining the ability to roll, and being able to land at low speeds.

Good thing they've got attitude control thrusters, then.

[Seto Kaiba]

It was just a thought, I wondered how exactly a VF without a horizontal stabilizer, and thus elevators, would change pitch in atmo, while maintaining the ability to roll, and being able to land at low speeds.

Well... you've got the ailerons for roll control, and then the outward-canted stabilizers ("ruddervators") and thrust vectoring for pitch. Beyond that, you've got the BLC, VFC, and verniers if you're in the mood to cheat a little.

As far as low-speed landings go... you really can't beat GERWALK mode vertical landing, but there's always leading edge and slotted fowler flaps to work with, in conjunction with the BLC.

[Andras]

Um... why would the actuator need to be aerodynamic? It's INSIDE the airframe in Bomber mode - when aerodynamics actually matter - and is only exposed for a couple seconds during transformation, tops.

Ahh, servo is a Mekton term. Each section of a mecha (main body, arms, legs, wings) are all servos. One of the abilities a transformable mecha has is to convert legs into wings.

[Seto Kaiba]

Ahh, servo is a Mekton term. Each section of a mecha (main body, arms, legs, wings) are all servos. One of the abilities a transformable mecha has is to convert legs into wings.

Oh. Well, that explains that then. I learned something new today.

Pretty sure the Konig Monster wouldn't be a candidate for an active aeroelastic wing there, on the grounds that it's more or less a lifting body aircraft...

Edited April 20, 2015 by Seto Kaiba

[Valkyrie Driver]

Well... you've got the ailerons for roll control, and then the outward-canted stabilizers ("ruddervators") and thrust vectoring for pitch. Beyond that, you've got the BLC, VFC, and verniers if you're in the mood to cheat a little.

As far as low-speed landings go... you really can't beat GERWALK mode vertical landing, but there's always leading edge and slotted fowler flaps to work with, in conjunction with the BLC.

Good point. I suppose I had forgotten about the V-tail, and the concept of ruddervators. I also hadn't considered the slotted flaps, which would also contribute to BLC if I'm not mistaken.

[GuardianGrey]

Thank you for your response, Andras, that was what I was trying to convey.

And even if the VB-6 is not a morphing/flexible wing, it is still an impressive feat of engineering to have the trailing edge of a wing (usually the thinnest/weakest part of) become the footplate for a 100+ ton unit.

Because I haven't seen MF, does the VB-6 ever go into its "destroid" mode (I would call it 'battroid' myself)?

Or does it only change to GERWALK mode (that looks more like the classic Monster destroid form)?

And how is the GERWALK form able to do Ground Effect with its wings being the legs?

[Seto Kaiba]

Good point. I suppose I had forgotten about the V-tail, and the concept of ruddervators. I also hadn't considered the slotted flaps, which would also contribute to BLC if I'm not mistaken.

From the look of the diagram in Master File, the VF-1 may have double slotted fowler flaps to play with... possibly to make up for its relatively small wing.

Because I haven't seen MF, does the VB-6 ever go into its "destroid" mode (I would call it 'battroid' myself)?

Or does it only change to GERWALK mode (that looks more like the classic Monster destroid form)?

And how is the GERWALK form able to do Ground Effect with its wings being the legs?

It does, but only in the final episode... after it gets its leg blown off and crashes on the Battle Galaxy.

The answer to your other question is "raw thrust". The engines are in the lower legs.

[Valkyrie Driver]

Do ruddervators need to be in a V configuration? or can those be used on the VF-171 as well?

[Seto Kaiba]

Do ruddervators need to be in a V configuration? or can those be used on the VF-171 as well?

Most of the time it's more like an X-shape in Macross (two dorsal, two ventral).

I think the stabilizers on the VF-4, VF-14, VF-171, etc. work just as well despite being inward-canted instead of outward... sort of an inverted V-tail, when you think about it.

[Valkyrie Driver]

So variable fighters in one way or another have all of the necessary control surfaces to be fully functional aircraft. I realize that flaps aren't necessary, since there are quite a few aircraft without them, but they are conducive to achieving lower landing speeds which is always a plus for a military aircraft.

[Mr March]

I think with the variable fighters the advanced OverTechnology permits them to cheat quite a bit. I think someone mentioned up above that the verniers could be used even in an atmosphere to turn tightly or even achieve lower landing speeds. And because of the thermonuclear reaction engines pumping out 650 MW per engine, power-to-weight ratio is far beyond anything we have now

[Valkyrie Driver]

Obviously the thrust vectoring will be used to enhance the flight characteristics of the fighter, so the control surfaces and the TV nozzles will move in concert with one another, but from a basic flight point of view they should have all of the necessary control surfaces, for the sake of redundancy, because redundancy is important for a military fighter.

[GuardianGrey]

I think I have seen that in a clip on YouTube (VB-6 Monster part II), Seto Kaiba, though I can't say for sure that it was in Destriod or GERWALK mode by the angle/view we are given as it floats off.

I know I did say the veinier thrusters could slowdown forward movement in the Real Life Technologies thread in referring to VTOL capability of a VF, though I agree that redundancy is a good thing at times.

Heck, my fan-made VF-19FXR did reintroduce the canards to the F-series, though also retained some of verniers from the space optimization. Redundant, though if needed, best to have.

Though not a VF, the SDF-1 had redundant systems for lifting (the rocket engines & gravitational turbines).

Odd thought, why has no one miniaturized the gravitational field systems to fighter-scale?

Or could the IVCS/ISC systems a development/spinoff of the attempt to do so, by compensating for G-forces with gravity/fold fields?

[Seto Kaiba]

I think I have seen that in a clip on YouTube (VB-6 Monster part II), Seto Kaiba, though I can't say for sure that it was in Destriod or GERWALK mode by the angle/view we are given as it floats off.

No, the bit I'm talking about is about 40 seconds after that part... the Konig Monster drifts off in Heavy GERWALK mode, and the next time we see it (circa 19:15), it's in Destroid mode, firing away with the forearm guns while Island-1 descends in the background:

I know I did say the veinier thrusters could slowdown forward movement in the Real Life Technologies thread in referring to VTOL capability of a VF, though I agree that redundancy is a good thing at times.

In actual fact, the VF-1 had a pair of verniers specifically for deceleration on the outside of its intakes...

Odd thought, why has no one miniaturized the gravitational field systems to fighter-scale?

Or could the IVCS/ISC systems a development/spinoff of the attempt to do so, by compensating for G-forces with gravity/fold fields?

Well... according to Master File, there's already a GIC system inside every thermonuclear reaction turbine engine, which is both the means by which the reaction is catalyzed and controlled and the method by which the resulting plasma stream is manipulated.

If I had to guess, I'd say that the reason nobody's tried to put an artificial gravity system on a VF is that there's too much potential to have something go badly awry... like what happened with the original ISC prototype, where it MAGNIFIED the g-forces on the pilot's body instead of reducing them, or having them somehow interfere with the GIC inside the reaction turbines. Using an AG field to simulate planetary gravity or provide deceleration forces wouldn't actually dampen g-forces from lateral motion either...

[GuardianGrey]

No, the bit I'm talking about is about 40 seconds after that part... the Konig Monster drifts off in Heavy GERWALK mode, and the next time we see it (circa 19:15), it's in Destroid mode, firing away with the forearm guns while Island-1 descends in the background:

vlcsnap-2015-04-25-13h20m19s194.png

Ah, I see now & the image answers helps answer the questions about how could the VB-6 utilize its weapons in Destriod mode.

I'm (most likely making a mistake and) assuming that the four (4) rail cannons are not able to be used in said form (due to the usual need of both legs and bracing plate to fire).

In actual fact, the VF-1 had a pair of verniers specifically for deceleration on the outside of its intakes...

I agree with that, Seto Kaiba, as was previously pointed out in the Real Life Technologies thread with Mr March's gif marking the FLIR sensors also as.

Well... according to Master File, there's already a GIC system inside every thermonuclear reaction turbine engine, which is both the means by which the reaction is catalyzed and controlled and the method by which the resulting plasma stream is manipulated.

If I had to guess, I'd say that the reason nobody's tried to put an artificial gravity system on a VF is that there's too much potential to have something go badly awry... like what happened with the original ISC prototype, where it MAGNIFIED the g-forces on the pilot's body instead of reducing them, or having them somehow interfere with the GIC inside the reaction turbines. Using an AG field to simulate planetary gravity or provide deceleration forces wouldn't actually dampen g-forces from lateral motion either...

On the effectiveness of gravity field manipulation, there is always room to debate, although the "oops" of the prototype ISC is not an usual fear of said systems.

Edited April 25, 2015 by GuardianGrey

[Seto Kaiba]

I'm (most likely making a mistake and) assuming that the four (4) rail cannons are not able to be used in said form (due to the usual need of both legs and bracing plate to fire).

Yep, per Macross Chronicle's VB-6 mechanic sheet, the Konig Monster can fire all of its weapons in Destroid mode. It supposedly uses its engines to stabilize itself.

On the effectiveness of gravity field manipulation, there is always room to debate, although the "oops" of the prototype ISC is not an usual fear of said systems.

Humanity's discovery that the Zentradi possess countermeasures for gravity control systems might have played a role too... and they found that out fairly early in the first space war.

[Valkyrie Driver]

So, here's another bit of a question, The VF-25 was intended to be the next generation of main line fighter right? It seems though that it was quickly surpassed by the VF-27 and YF-29, which both seem to have more internal armaments than the VF-25. Why did they move from internal armaments on the VF-25, and then Bring them back for the VF-27 and YF-29?

The heavy battroid of the VF-17/171 has internal micromissile launchers, do the leg bays on the VF-19 perform the same function, or is that simply a consideration from the passive stealth silhouette of the VF-17?

[Seto Kaiba]

So, here's another bit of a question, The VF-25 was intended to be the next generation of main line fighter right?

Sort of... the VF-25 was meant to be the next main fighter for Frontier (and its close allies). The YF-24 specs were redacted a bit and sent to all of the emigrant fleets and planets with a sort of "do whatever with this" kind of attitude.

It seems though that it was quickly surpassed by the VF-27 and YF-29, which both seem to have more internal armaments than the VF-25. Why did they move from internal armaments on the VF-25, and then Bring them back for the VF-27 and YF-29?

In terms of raw flight performance or technological sophistication perhaps, but both the VF-27 and YF-29 suffer from low versatility as a result of the overwhelming emphasis on anti-Vajra combat. Neither could honestly match a VF-25 for general purpose-fulness or the sheer diversity of combat roles it can fill. Not to mention ANYONE can fly a VF-25, while only cyborgs can fly the VF-27, and the YF-29 is prohibitively resource-intensive.

Thr VF-27 plays by different rules because it was developed by a different fleet and different designer to fight a single foe... the Vajra. The YF-29 was likewise built for that one fight. To incorporate the same levels of firepower as a VF-25 with FAST packs without sacrificing the insanely high performance that was their overriding design consideration, internalizing their armaments was the only way to go... even if it ultimately restricted the types of armaments used.

The heavy battroid of the VF-17/171 has internal micromissile launchers, do the leg bays on the VF-19 perform the same function, or is that simply a consideration from the passive stealth silhouette of the VF-17?

Yes, the VF-19's internal modular ordinance bays are meant to allow the fighter to carry various types of armament without compromising passive stealth... though that became less of a concern after the better active stealth systems were implemented on the production model.

[Mommar]

I still don't know how you manage to keep all of this stuff straight, Seto.