A couple of months ago I’ve noticed that the F-15C handles very differently, than the F-15A. After some flight testing I realized the gap between the 2 aircraft is quite massive, the F-15A pretty much always wins in a dogfight quite easily, despite the real life performance of the 2 airframe should be very close. So I’ve decided to dig into the issue and it seems the newly added F-15C variants (that includes the japanese one) are massively overweight.
Here are the operational empty weights of ALL the F-15C variants:
-F-15J (which is a licenced build F-15C): 12820 kg or 28 263 lbs
-F-15J(M) (which is a licenced build, modernized F-15C): 13030 kg or 28 726 lbs
-F-15C MSIP II and Baz Meshupar (both have the same weight): 13470 kg or 29 696 lbs
I checked a couple of sources and it seems the current weight for the F-15C MSIP II is likely closer to the 2 seater F-15D. I found 1 manual, which deals with the MSIP II variants as well and looked up a lot of secondary sources. The manual states, that for the F-15C/D model the operational empty weight is around 29 000 lbs, while the secondary sources I’ve looked up more consistently place the F-15C’s empty weight to be 28 000 lbs. My observation is, that the newer the source it is more likely it places the F-15C’s weight to be the aformentioned 28 000 lbs. Now I understand, that the Devs use the so called operational empty weight (true empty weight + oil + stuck fuel + pilot) and none of these sources clarify what they mean by empty weight, but as a lead 2 sources mention a 600 lbs difference between the F-15A and F-15C, which leads me to believe this 28 000 lbs is actually the operational empty weight. In game, the F-15A 12 380 kg or 27 293. Now this number is quite close to the F-15A/B numbers (27 500 lbs) present in the manual, which also states the figures presented are rounded to the nearest 500 lbs. Adding this 600 lbs extra, we would arrive very close to the quoted 28 000 lbs, 27 893 lbs to be precise. What are your thoughts on the matter? Can anyone also help me with checking some sources to clarify the matter?
Sources (https://archive.org):
F -15 Eagle - America’s First Air Superiority Fighter p 45 (empty weight)
/details/f-15-eagle-americas-first-air-superiority-fighter/page/n43/mode/2up
The great book of modern warplanes by Spick, Mike (2002) p 137 (empty weight)
/details/greatbookofmoder0000spic
The Great Warplanes of the 1980s by Yenne, Bill p 50 (empty weight)
/details/greatwarplanesof0000yenn/page/n1/mode/2up?q=The+Great+Warplanes+of+the+1980s
Aerofax Datagraph 6 McDonnell Douglas F-15A/B/C/DIE Eagle/Strike Eagle by Dennis R. Jenkins (1990) p 9. paragraph 4, line 4: „an empty F-15C is about 600 Ibs. heavier than an F-15A.”
/details/aerofax-datagraph-006-mcdonnell-douglas-f-15a-b-c-./mode/2up"
McDonnell Douglas F-15 Eagle: Supreme Heavy-Weight Fighter by Dennis R. Jenkins (1998) p 33 paragraph 3 line 5-7: An empty F-15C is about 600 lbs heavier than the typical F-15A."
/details/f-15-eagle-2/F-15%20Eagle%20%282%29/page/33/mode/2up
Sources 2:
On the F100 engine documents, the A is stated as 27,700 lbs but they are rounded to the nearest 500 pounds as you can see on the 86 change of the flight manual and on the 220 manual, 28k lbs.
Pre-MSIP F15C WITH F100s is 28,600 lbs and with 220 engines you have an increase of roughly 1k lbs.
The problem with performance you see is mostly due to engine thrust.
This is an F15C MSIP using 220 engines acceleration at 40k ft. The Red line is the ingame performance. Much lower Top speed and much lower acceleration. Currently the F15A performs better than the F15C at high altitude when is should be the other way around. The F15C should be able to overspeed itself under 40k ft.
But ofc, report goes NOT A BUG, Community Bug Reporting System.
Meanwhile F-15A matches but they can’t make F-15C match…
Not excessive. On the flight manual, read the Gross weight part.
and SHALL NOT be used for…
Its mostly to give you an idea.
Performance appendixes have more information, more detail and are for performance calculation stuff.
MSIP 1k lbs gain, wasn’t “just for some” modifications. It included amraam adaptability, EWWS to TEWS, ECM & FLARES, amraam provision gps and other stuff.
You also need to factor weight changes from 100 engine to 220 engines. Some F-15C had apg 70s which we dont know if they was weighr increase or decrease. It all adds up.
https://www.si.edu/object/pratt-whitney-f100-pw-100-turbofan-engine%3Anasm_A19900276000
So there is 600 pounds, that needs to be found. However it’s still a bit odd and most sources I quoted already deal with the MSIP II program, including the TO in one way or an other. As far as I am aware, during such upgrades manufacturers try to avoid adding extra weight as much as they can to avoid the degradation and performance and not cause issues with the aircraft’s balance. Can you please share your source? I would like to check it and see how it compares against the TO I saw, maybe there lies the answer. Also your point about the performance graph is quite interesting.
Thanks, but that’s where I started. At first I tried to get some source material from Gaijin through the reporting system, but they didn’t reveal their sources and pointed towards the forum to discuss the issue. If there is enough evidence, I will submit a bug report, but I want to be sure. So if you have some material, that could contradict or add to this case feel free to post it… that’s why I turned to Gaijin and the forum in the first place.
And as you know. That is not always acheived, weight increases.
It comes from Appendix A(100s) and Appendix B(220s) from 1989. If you look at appendix A from the 1986 change(from the manual you posted), it puts the F15A at 27,500 and (100 non-msip)F15C at 28,500, it was put on a diet and lost weight between 1986 and 1989?
Weight is not exact exact. Rounded. So don’t sweat it. The issue is thrust, by a big factor.
Though I agree to just stick to 29,500lbs rather than the 29,700 we have currently.
For the Japanese idk why its lower as I don’t follow it.
Issues like radar missing 2/5ths of it max range, faster scan rate at 10 and 20N.M, no radar warning warning when launching sparrows, engine thrust, and missing HPRF TWS are far more important and do a difference but not done as developers use soviet sources despite speciric primary documentation stating otherwise
I’ve noticed they react quite harshly to any attempt aimed at correcting the F-15C, so it’s more likely they think it’s good for “balance”. However, it’s quite contradicting to their mission statement about “realism”. I think I’m going to dig deeper into the issue, since even newer magazines state a lower weight and they swear they base their numbers on proper manuals. Do you think there is any chance for a newer manual, possibly from the 90’s? That would clarify a lot I guess.
Okey guys, in the meantime I’ve started to look around for a couple of documents and I came across an interesting piece of document I’ve found on Scribs. It’s a Standard Aircraft Characteristic (SAC) document directly from McDonell Douglass and in it they give an exact number for the weight of the MSIP F-15C’s. The document is from 1992. On page 3 at the top right corner the empty configuration of the plane is 28 476 lbs with the PW 220 engine. Also I’ve also seen 2 other documents from McDonell, Eagle talk volume II and volume III. While these last 2 documents don’t exactly mention the weight of the aircraft, they indirectly provide some weight information, that indicate consistency across these documents. For example: In the SAC, on page 4 full internal fuel is stated to be 13 455 lbs, while in Eagle talk Vol II on page 28 it says: “The new fuel arrangement in the C/D can really give you long legs. With internal fuel only, you should see 13,400 pounds on the gage at engine start.” So in short, I think we have the proper empty weight for the MSIP II and Baz Meshupar. Now only the Japanese versions remain, but based on this info, they should be lighter too.
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