Talk:Boeing F-15EX Eagle II

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The Boeing F-15EX Eagle II is an American multirole all-weather strike fighter manufactured by Boeing Defense, Space & Security. Derived from the McDonnell Douglas F-15 Eagle and first conceived in 2018, the F-15EX is not expected to survive against modern air defenses by 2028, but has the capability to perform homeland and airbase defense, enforce no-fly zones against limited air defenses, and deploy standoff munitions. The aircraft made its maiden flight in February 2021, and as of 2023 has a total planned fleet size of up to 104. This F-15EX, from the United States Air Force's 40th Flight Test Squadron, was photographed flying over northern California during an aerial-refueling operation in May 2021.

Photograph credit: Ethan Wagner

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Florida ANG

I won't start an edit war but the source as originally written https://web.archive.org/web/20200927161831/https://www.af.mil/News/Article-Display/Article/2314043/air-force-announces-guard-locations-for-f-35a-f-15ex/ specifically refers to the Florida ANG receiving the F-35A, not the F-15EX. The quote "the Air Force plans to replace the Air National Guard’s aging F-15C Eagles in Florida and Oregon with the service’s newest air superiority aircraft" is either referring to both the F-35A and F-15EX or is simply a mistake much like the announcment[1] about basing the F-15EX in California and Louisiana calling the Eagle II a 'Strike Eagle'.

Other sources from the time likewise refer to only the Oregon ANG units getting the F-15EX: https://www.airforcetimes.com/news/your-air-force/2020/08/20/here-are-the-air-national-guard-bases-that-will-get-the-f-35-f-15ex/ & https://www.airandspaceforces.com/f-15ex-headed-to-oregon-florida-as-usaf-decides-on-fighter-bases/. I believe the latter source explains the confusion as that specifically refers to the test squadrons at Eglin receiving the F-15EX, not the ANG wing at Jacksonville. I won't revert the article again but I just wanted to explain my point of view.

Thanks, F4JPhantomII (talk) 19:10, 20 April 2023 (UTC)

• OK, that makes a lot more sense now. Thank you. -Fnlayson (talk) 01:57, 21 April 2023 (UTC)

Trust/Weight wrong?

Trust/weight seems to be based on the calculation 29,500 (afterburning trust, per engine) / 31,700 (empty weight) = 0.9305, 0.93 listed as a figure. Am I wrong in assuming it should be double that, or is there some other calculation that gives the same figure and is correct? 213.124.170.231 (talk) 14:07, 30 June 2023 (UTC)

The F-15EX weighs considerably more than 31,700 lbs, which represents early weight of the F-15E without all of the additional avionics and upgrades over its service life. The current F-15E with the F100-229 engines weighs about 34,600 lbs empty, and the F-15EX is slightly more than that. Thrust-to-weight ratio here is typically for loaded gross weight, although much of the numbers here are just figures for the F-15E as official ones for the EX haven't been published yet. Steve7c8 (talk) 20:35, 13 February 2024 (UTC)

Why would the F-15EX have a similar weight to the F-15E when it has fly-by-wire? The F-15QA is specified at 31,700 lbs empty. Shouldn't this also reflect the F-15EX? 184.174.197.4 (talk) 20:22, 26 February 2024 (UTC)

The T/W ratio is based on total thrust divided by the typical operating weight or gross weight, not empty weight. See F-15 specs section for an example. -Fnlayson (talk) 22:25, 26 February 2024 (UTC)

I understand that, but my point is that the F-15EX has fly-by-wire, so it should be lighter than the F-15E. The F-15E has an empty weight of 34,600 pounds, while the F-15QA has an empty weight specified at 31,725 pounds. For the F-15E, 34,600 pounds, plus 13,455 pounds of internal fuel, plus 3045 pounds for combat configuration, gives a gross weight of 51,100 pounds, and a T/W ratio of 0.93:1 with the F100-PW-220 engines putting out 23,470 thrust each. For the F-15QA with the same amount of fuel and combat load, gives a gross weight of 48,225 pounds, and a T/W of 1.22:1 with the F101-GE-129 engines putting out 29,500 pounds of thrust each. My argument is that the F-15EX should have a weight and T/W similar the F-15QA, as they are both advance eagles with fly-by-wire.

btw, the F-15E would have a T/W of 1.14:1 with the F100-PW-229 engines, which output 29,160 pounds of thrust each. 184.174.227.72 (talk) 20:22, 27 February 2024 (UTC)

• The F-15QA variant incorporated a revised wing structure which probably increased the empty weight some. I'd guess they did little to reduce weight due to the FBW system also. -Fnlayson (talk) 21:38, 27 February 2024 (UTC)

Fly-by-wire doesn't necessarily reduce the weight of the flight controls, if all of the hydraulic circuits and actuators are the same, and the weight differences between the legacy Control Augmentation System and the fly-by-wire would not be significant. What's your source on the empty weight of the F-15QA? Steve7c8 (talk) 21:48, 27 February 2024 (UTC)

Admittedly my source was far less reliable than I initially thought (CMANO, which I had only just now learned what that was). Regardless, assuming an identical weight to the F-15E, that would still give a T/W ratio of 1.15:1. 64.189.25.28 (talk) 00:01, 28 February 2024 (UTC)

The gross weight of the F-15EX will depend on what the typical combat loadout is. With the legacy F-15C/D, they rarely took off without two 600 gal wing tanks, and the F-15E almost always took off with CFTs. Using a thrust-to-weight ratio that only has internal fuel would be a highly unrealistic and uncommon loadout. Steve7c8 (talk) 17:59, 2 March 2024 (UTC)

I figure it should be noted that there the US Air Force F-15EX order includes variants both with and without CFTs. Perhaps it would be a good idea to include both values and note the origin of the difference.

Per my calculations: at 29,500 lbs of thrust from each engine at full thrust (59,000 lbs total) and a weight of 34,600 lbs plus 13,455 lbs of internal fuel (48,055 lbs total) without CFTs, the T/W is 1.23. I don't have a reference offhand for the weight of the CFTs when fully fueled. And of course, this doesn't account for any additional weight from a combat configuration. Brainandforce (talk) 21:51, 23 August 2024 (UTC)

All of this is why some of us recommend not making one's own calculations for Thrust/Weight Ratio. Instead, we should only cite reliable published sources that give the Thrust/Weight Ratio, preferably with the thrust and weight used for their calculations. In most cases, Thrust/Weight Ratio just amounts to a dick-measuring contest between favorite aircraft. BilCat (talk) 00:12, 24 August 2024 (UTC)

Role of former Assistant/Acting SecDef Patrick Shanahan

One thing that's noteworthy is that at the time when the F-15EX was being discussed and finally procured, one of the DoD officials in office was the Assistant and eventually acting SecDef Patrick Shanahan, who had a management role at Boeing prior to becoming the Assistant SecDef. While the ethics commission at the DoD did say that Shanahan was barred from the F-15EX decision, he reportedly advocated for Boeing during his time as the acting SecDef and Boeing did receive disproportionate amount of contracts during his tenure; as far as how much that influenced the decision, I don't know. As such, I don't know if this is something worth mentioning in the article. Steve7c8 (talk) 20:52, 13 February 2024 (UTC)

References

Steve7c8 (talk) 20:52, 13 February 2024 (UTC)

Order of variants

I think the F-15EX article can be used to as a "catch-all" to capture the F-15 Advanced Eagle as a whole, which actually began with the F-15SA. Since both the F-15SA and QA predate the EX, does it make sense for those variants to be listed before the EX? Steve7c8 (talk) 21:21, 13 February 2024 (UTC)

Yes, all these recent variants seem related enough to be covered together here. -Fnlayson (talk) 21:47, 13 February 2024 (UTC)

Quality assessment

I've expanded the article considerably in the past couple of days, should we do a quality reassessment to see where it stands? Steve7c8 (talk) 16:54, 15 February 2024 (UTC)

It will probably rate as a C as a minimum, or maybe B, depending on completeness imo. -Fnlayson (talk) 17:53, 15 February 2024 (UTC)

Infobox

I like some input on how to approach this. This article is mainly about the F-15EX but is now encompassing all Advanced Eagle variants that starts from the F-15SA. How do we want to have the information in the infobox be presented? Just the F-15EX or all Advanced Eagles? A compromise may be to include both in separate lines, but that makes the infobox cumbersome. Steve7c8 (talk) 11:33, 17 February 2024 (UTC)

I think using Advanced Eagles would be the simplest for a main label. But details for each variant does not have to be listed if they are generally similar, imo. -Fnlayson (talk) 15:32, 17 February 2024 (UTC)

Maximum speed

I noticed that the maximum speed was changed to Mach 2.9, citing a statement from the Boeing PM in an Aviation Week article. Speaking as someone who has worked in the industry, I find this claim highly implausible. There are issues of thermal limitations of the windscreen and the aluminum structure that the F-15 is predominantly built out of, inlet stability, shock impingement, and other potential issues. The only aircraft that ever flew at such speeds are either built from steel such as the MiG-25, MiG-31, XB-70, or titanium alloy such as the A-12 and SR-71. The article also doesn't make it clear if this was an airspeed that the aircraft was actually tested to, or if it refers to some kind of limit beyond the operational conditions. For instance, Mach 2.9 could be a reference to the flutter limit, which is a 15% margin above the maximum speed, so for a Mach 2.5 limit speed, the flutter limit would be Mach 2.875, or roughly 2.9. The manuals for the Advanced Eagle hasn't changed and still indicates a Mach 2.5 limit even when clean with no pylons.

In short, speaking as an engineer and also from reviewing manuals and documentation, it's highly doubtful that Mach 2.9 is a speed that was actually tested, and I would postulate that it's more likely some kind of theoretical limit as discussed above. Steve7c8 (talk) 14:28, 22 February 2024 (UTC)

From the article:

"Specifically, the not-to-exceed speed of the twin-engined fighter is about Mach 2.9, or about 2,225 mph at sea level, Novotny said. That puts the top speed of the Eagle II within about 80 mph of Mach 3, a speed only a few aircraft powered by gas turbines have achieved....'Remember, we’re testing when it’s clean,' Novotny said. 'So it’s not carrying a bunch of stuff on it. And in that airshow configuration, with the two big GE [F110-GE-]229 engines, it’s putting out 29,500 pounds of thrust per side.'”

This implies that Mach 2.9 was done in an actual test flight. I believe the F-15EX has 70% parts commonality with the F-15c. How that would impact top speed I'm not sure. Replacing the windscreen I know would be easy. The rest, I'm not qualified to answer that. 184.174.227.36 (talk) 21:35, 22 February 2024 (UTC)

It's the F110-GE-129 engine, which has roughly the same static thrust rating as the F100-PW-229. The flight manual Technical Order 1F-15E-1 clean envelope charts for the F-15E indicate maximum speed of Mach 2.4 with the F100-PW-220, and Mach 2.3 with the F100-PW-229, both at standard day temperature at high altitude; Mach 2.5 is possible at 10 degrees Celsius below standard day at high altitude. Keep in mind that any speed above Mach 2.3 is marked as a time-limited pursuit of just 1 minute. Given the substantially higher thermal environment a Mach 2.9 versus Mach 2.5, 581 K (308 °C; 586 °F) versus 487 K (214 °C; 417 °F) at standard day at high altitude, I find it implausible that Mach 2.9 was the tested speed, and the envelope charts (which are the same as the F-15SA and QA) have not changed. In short, I would be more comfortable if there is additional corroboration, but right now I would rather not adjust the number based on a single statement; no sources are immune to mistakes, even normally reputable ones like Aviation Week & Space Technology. Steve7c8 (talk) 14:56, 23 February 2024 (UTC)

It turns out that the Boeing PM misspoke. It’s Mach 2.497, not Mach 2.9. Steve7c8 (talk) 17:29, 24 February 2024 (UTC)