The VF-19 Excalibur engine ratings in the Macross Chronicle

[Mr March]

After a conversation with Seto Kaiba yesterday, I decided to write an exhaustive analysis for the apparently bizarre published engine ratings of the VF-19 Excalibur in Macross Chronicle issues #27 and #41. I'm posting it here before inclusion on my website for the submission of any thoughts, corrections or questions fellow interested fans may have.

NOTE: Please ignore the HTML tags

Analysis: The VF-19 Excalibur engine ratings in the Macross Chronicle

A rather interesting development in the published statistics of the variable fighters occurred in Macross Chronicle issue #27. Sheet 27-02 provided statistics for the VF-19<u><b>S</u></b> Excalibur in which the engine thrust for that variable fighter is rated at 68,950 kg each whereas the VF-19S engines were previously rated at 78,950 kg each. Much later in Macross Chronicle issue #41 the statistics for the VF-19<u><b>F</u></b> Excalibur were published. Sheet 41-08 describes the VF-19F engines rated at 78,500 kg each whereas they were previously rated at 72,500 kg each. This new information has created a unique aberration in valkyrie performance whereby a standard model variable fighter (the VF-19F) is now superior to the team leader/commander type variable fighter (the VF-19S). It is clear such a bizarre development warrants examination to either acknowledge the trivia, rationalize the issue, or debunk an honest error in publication.

There are two issues that arise from the trivia published in Macross Chronicle issues 27 and 41:

1) The VF-19F maximum air speed is still published in the Macross Chronicle as Mach 5+ while the VF-19S maximum air speed is Mach 5.1+, apparently ignoring the fact that the new VF-19S engines have far less thrust than the new VF-19F engines. The Chronicle also confirms the weight of the VF-19S (8.62 tons) is heavier than the VF-19F (8.55 tons). Since both the F and S airframes are virtually identical, it would be physically impossible for an aircraft with less engine thrust and more weight to achieve a superior speed. The Chronicle also confirms the climb rate of the VF-19F is 65,000 meters per second while the VF-19S climb rate is 68,000 meters per second. Again, this information creates a contradiction in which the newly rated VF-19S is supposed to have inferior engine thrust to the VF-19F and yet the S type is achieving an impossible superiority. Macross Chronicle issue 41 attempts to acknowledge the problem with a sentence which reads: <i>While the F-type has superior engine thrust compared to the S-type, it has inferior cruising speed and rate-of-climb from sea-level</i>. However, rather than provide a solution the sentence only serves to highlight the contradicting performance ratings between the two VF-19 types. Thus the issue remains unresolved.

2) The new engine ratings provided in the Macross Chronicle appear to contradict established literature for variable fighter thrust ratings. Until publication of Chronicle #27, the performance of a team leader/commander type variable fighter was always superior to the standard mass-produced model variable fighter, either by higher engine ratings or descriptive trivia. This can be verified by official trivia for the VF-1 Valkyrie (VF-1S written description), the VF-17 Nightmare (D/S engine ratings), the original VF-19 Excalibur (F/S engine ratings) and VF-25 Messiah (VF-25S written description). The Chronicle also adheres to established performance ratings between standard and leader models for all other valkyries with the only exception being the VF-19 Excalibur.

In summary, it appears most likely the engine thrust rating for the S type VF-19 Excalibur variable fighter provided in Macross Chronicle #27 is a simple error on behalf of the writers. When the Chronicle profiles the F type VF-19 Excalibur later in issue #41, it appears the writers discovered the problem created by their error in issue #27 and attempt to explain away the error with a poorly rationalized line of trivia.

Rather than perpetuate this error I have decided to detail the genesis of the problem and document it in this dedicated section. The change of engine thrust rating can be easily explained as transposition errors on behalf of the writer of Chronicle issue #27. The Chronicle rating for the VF-19F engines previously rated at 72,500 kg become rated at 78,500 kg in the Macross Chronicle, which transposes the second digit of the VF-19S atmospheric thrust rating (68,500 kg). Further, the new VF-19S thrust rating of 68,950 kg listed in the Macross Chronicle appears to be the result of a transposition error of the first digit of the atmospheric thrust rating (again, 68,500 kg) with the <u>previous maximum thrust</u> rating of the VF-19S (78,950 kg). With that in mind, the original VF-19 Excalibur engine thrust ratings (72,500 kg for the F type and 78,950kg for the S type) will remain on the <b>Macross Mecha Manual</b> and footnotes will direct curious fans to this section for an explanation of the Macross Chronicle figures.

[Talos]

After a conversation with Seto Kaiba yesterday, I decided to write an exhaustive analysis for the apparently bizarre published engine ratings of the VF-19 Excalibur in Macross Chronicle issues #27 and #41. I'm posting it here before inclusion on my website for the submission of any thoughts, corrections or questions fellow interested fans may have.

NOTE: Please ignore the HTML tags

I have to get rid of this headache that's pounding in my head if I want to give you a more in-depth and longer reply, but I'm just going to say that it seems like a typo for me and the VF-19S should properly be 78,950 kg thrust per engine.

[David Hingtgen]

I wouldn't accept any other explanation other than a simple typo. 78950 vs 68950.

PS---top speed in a plane isn't necessarily a function of engine power. Many are limited by heat. IIRC that's actually explained as part of the VF-27's profile, in that it can divert PPB energy to "the forward shields" as a temporary measure to protect against extreme heat, and thus go much faster than the VF-25. Yes, it requires the VF-27's extra thrust to do so, but without heat protection the structure wouldn't be able to take it regardless of how much power you had.

The F-111, F-15, and SR-71 are all limited by heat, rather than the power of their engines. (the MiG-25 is pretty much limited by fuel consumption--it can suck its tanks dry while still accelerating)

[Ghost Train]

Just a few nerd observations here:

1) Mach is not a measure of speed. As discussed in the Aircraft thread, it is the ratio of your own velocity to the speed of sound at a given altitude/pressure/temperature. m/s divided by m/s cancels out all units, it is therefore just a plain ratio - it is not velocity or speed.

Given that observation, it makes sense reporting different Mach numbers, as the speed of sound differs. A mach number at sea level will be substantially different than a mach number at high altitudes. Furthermore, as you hit LEO, your Mach number becomes pretty pointless as there is little to no "air" left for sound waves to propagate through, it might as well be infinity.

2) It makes no sense to report an engine rating with kg (lol what's that supposed to mean, how much it weighs ).

Thrust is a force, hence a unit like a Newton would be more appropriate. This is probably a common mistake due to the fact that Imperial units use Pound-Force in lieu of Newtons. Unfortunately, it is frequently abbreviated as lb which can also just mean pounds. The valkyrie source material probably just took 50,000 lb (or whatever) and misinterpreted it as meaning pounds as opposed to pound-force and just transformed the units straight to kilogram.

[David Hingtgen]

Yup. I discussed pounds vs pounds-force vs kilograms vs kilonewtons with Graham a while ago, with regards to how valk engine thrust is reported.

Darn gravity, always screwing up our valk calculations!

(I didn't feel like pointing out the lack of "N" in the VF-19 specs, as that's not really part of the discussion)

As for Mach--since no plane can achieve full speed at sea level, and Mach 1 is pretty constant from 35,000 to 80,000ft (where most planes achieve max speed), everyone just uses that. 660mph.

[azrael]

Blame Kawamori and the Chronicle editors.

Heck, the VF-19S' engines use to be FF-2550Js and then they became FF-2550Xs. And heck, the VF-19As 56,500 kg FF-2200 engines still give it a max velocity of Mach 5.1+ @ 10,000m and the VF-19A is the heaviest of the family (from my last check).

[Seto Kaiba]

2) It makes no sense to report an engine rating with kg (lol what's that supposed to mean, how much it weighs ).

Or we could make the safe assumption that they just goofed on the symbol and meant kilograms-force. There's a nice, quick conversion for that to kilonewtons. Just multiply it by 0.00980665.

Blame Kawamori and the Chronicle editors.

lol, it was still a fun conversation we had about it... just a WEIRD typo. I read that page like eight times before I noticed it too... XD

[thegunny]

I think it's reason enough to get out the tanto & rice paper

[azrael]

And if you want a real headache, the VF-171EX's FF-2550F engines, which are noted as the same used in the the VF-19, are rated at 67.5t (max. output in space).

[Ghost Train]

As for Mach--since no plane can achieve full speed at sea level, and Mach 1 is pretty constant from 35,000 to 80,000ft (where most planes achieve max speed), everyone just uses that. 660mph.

Not exactly a plane lol, but wasn't there a rocket car/boat a few years ago that exceeded the speed of sound?

[Mr March]

Thanks for the comments everyone. I'm glad this analysis was helpful. While errors and omissions are not exactly new to the Macross Chronicle, many of them are not as easy to diagnose as this VF-19 engine issue was. But it helps to have something written down for future reference.

Regarding the unit "kg", the unit does indeed stand for "kilograms-thrust" or "kgf". I can understand the confusion since the term is apparently obscure. It is not an officially recognized unit but was apparently used by Russians in their rocket engineering. All the Macross productions up to Macross Dynamite 7 published their official statistics using thrust ratings in "kg". This was likely adopted from Mobile Suit Gundam and from there I've no idea where it came from or why. Starting with Macross Zero the thrust ratings have been more properly expressed in kiloNewtons (kN). I went through the trouble of converting all the old statistics for the mecha from SDF Macross through Macross Dynamite 7 to kiloNewtons. Thrust ratings in kN can be found in each Valkyrie profile in green colored text, so that fans can compare engine performance between all the old mecha to the Macross Zero/Frontier mecha.

Regarding the VF-171EX Nightmare Plus engines, the thrust ratings can either be expressed as 67.5 tons or 67,500 kg. Either expression is accurate and each displays the same measurement just in a different order of magnitude. The VF-171EX Nightmare Plus engine ratings equate to roughly 662.18 kN of thrust per engine. The Macross Chronicle has provided enough statistics to calculate a Thrust-to-Weight ratio for the VF-171 and VF-171EX (as well as several other earlier Valkyries) and those will be included in the next update. For those fans who are interested, I'll post the VF-171 T-W ratios (and the original VF-17 Nightmare ratios) below for comparison.

VF-17D Nightmare (empty) = 9.28

VF-17S Nightmare (empty) = 10.04

VF-171 Nightmare Plus (empty) = 7.48

VF-171EX Nightmare Plus (empty) = 10.42

[David Hingtgen]

Not the weight ratios again! Yeesh, there's still no agreement for modern real-life planes... (as wikipedia lists the F-15 and F-22 at exactly the same)

[DrStrangelove]

As for the velocity differential the S can be faster if it has a lower drag coefficient, an SR-71 has a lower thrust ratio than an F-15 or F-22, but it is a much cleaner aircraft. This wouldn't explain the higher climb rate however, unless it's supposed to be for initial climb rate as opposed to sustained climb, in which case the lower powered S would initially climb faster due to higher initial kinetic energy. If this is so the S might make it to say 10km quicker but the F would pass it up and make orbit first. Or it could just be another goof(retcon?, like the size of the factory satellite).

[David Hingtgen]

SR-71 engine is optimized for high-speed high-alt performance. At speed and altitude, a J58 is pumping out way more thrust than an F100. Same reason an F-4, drag-hog that it is, with only a bit more than half the power of the sleeker F-15--is only slightly slower. The F-4 has a turbojet, the F-15 has a turbofan. And in high-alt high-speed situations, a turbojet reigns supreme over a turbofan.

"25,000lbs" is the thrust rating AT SEA LEVEL for a plane with ZERO FORWARD AIRSPEED. (which is why most specs say "static thrust" and sometimes mention sea level)

At 50,000ft at 1500MPH, the relative thrust ratings of a ramjet vs a turbofan will change drastically.

[Mr March]

The thrust-to-weight ratio is totally valid for the intended purpose; a simple and convenient way to express Valkyrie statistics through a single figure. Fans can then use that figure to easily compare one Valkyrie to another Valkyrie, or even to a real world jet fighter. The ratios are not designed as an exhaustive academic dissertation on the subject (nor is there enough official trivia for any such examination of any aspect of the Valkyries). Again, the appearance of thrust and weight figures in Macross is very likely another aping of the original Mobile Suit Gundam series which actually provided derived Thrust-to-Weight ratios in published statistics (the ratio was titled "maximum thruster acceleration" in Gundam, but is the exact same figure as a Thrust-to-Weight ratio). The only difference is the Macross writers simply provided sufficient figures for thrust and weight and wanted fans to do the math themselves. So we have

[DrStrangelove]

SR-71 engine is optimized for high-speed high-alt performance. At speed and altitude, a J58 is pumping out way more thrust than an F100.

J58s crank out more power than an F100 at any altitude. Most its superiority at high altitude is derived from its quasi-ramjet like properties

Same reason an F-4, drag-hog that it is, with only a bit more than half the power of the sleeker F-15--is only slightly slower. The F-4 has a turbojet, the F-15 has a turbofan. And in high-alt high-speed situations, a turbojet reigns supreme over a turbofan.

This generally only applies to high-bypass ratio turbofans like on airliners/cargo planes, in which the fan stage grossly outsizes the actual combustion stages. This doesnt really apply so much to low bypass engines used by most high perfomance combat aircraft

"25,000lbs" is the thrust rating AT SEA LEVEL for a plane with ZERO FORWARD AIRSPEED. (which is why most specs say "static thrust" and sometimes mention sea level)

The same sort of thing applies to turbojets, all combustion engines power output falls off at high altitude as atmospheric pressure drops

At 50,000ft at 1500MPH, the relative thrust ratings of a ramjet vs a turbofan will change drastically.

As it would for a turbojet, they also possess all the fans and whatnot slowing down the rarefied air

[Seto Kaiba]

Or it could just be another goof(retcon?, like the size of the factory satellite).

While I'm no expert on aerodynamics, the way the Macross Chronicle sheet presents those numbers makes it look like a transposition error that they then went back and tried to justify, rather than something they'd initially intended to do. The original numbers are much more consistent with what we've come to expect from "leader" models in Macross. Only one digit actually changed between the two models... the VF-19F took the VF-19S's atmospheric thrust limitation and then stuck a 7 where the 6 should be, while the VF-19S's took its normal thrust rating, omitted the atmospheric limitation, and replaced the leading 7 in the normal thrust rating with a 6.

[DrStrangelove]

While I'm no expert on aerodynamics, the way the Macross Chronicle sheet presents those numbers makes it look like a transposition error that they then went back and tried to justify, rather than something they'd initially intended to do. The original numbers are much more consistent with what we've come to expect from "leader" models in Macross. Only one digit actually changed between the two models... the VF-19F took the VF-19S's atmospheric thrust limitation and then stuck a 7 where the 6 should be, while the VF-19S's took its normal thrust rating, omitted the atmospheric limitation, and replaced the leading 7 in the normal thrust rating with a 6.

Yeah I would consider that the most likely explanation, I was just providing a possible rationalization.