F-15 performance changes due to engine differences

Cold war, Korea, Vietnam, and Desert Storm - up to and including for example the A-10, F-15, Mirage 200, MiG-29, and F-18.
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sprstdlyscottsmn

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Unread post22 Aug 2017, 18:28

The purpose of this thread is to go over the acceleration and top speed differences between the F-15 and it's use of the F100-PW-100(C), F100-PW-220(C/E), F100-PW-229(E), and F110-GE-129(S/SA/SG/SK) motors.


Disclaimers:

F110 performance is estimated relative to the F100-PW-229 via measuring the difference between the motors is the HAF F-16-1. As the F-16 has fixed inlets and the F-15 has variable inlets an assumption is made, in lieu of hard data, that the difference in dynamic thrust calculated for the F-16 transfers over to the F-15. All other accelerations are taken directly from the manuals.

Dynamic excess thrust is taken against fixed weights as the F-15 charts do not include distance or fuel burned in their acceleration charts. As weights become standardized this should still be relatively accurate for showing relative differences in thrust.

Only 40,000ft performance is looked it.


Using the listed Acceleration charts in the various F-15 -1s I used a dV/dt to find acceleration and then divided by the starting weight to get an 'Excess Thrust', or the force available to push the plane faster. As the weight used is constant and the accelerations were from flight test data where fuel is being burned the actual excess thrust would be fractionally lower across the board.
Excess Thrust.JPG

Excess Thrust 2.JPG


The difference between the F100-PW-229 and the F110-GE-129, as a pair, was as follows from the F-16-1. As the inlet limit for the F-16 is around 2.0M no additional data was available beyond that point so no extra thrust was allotted for the F-15 estimations.
GEvsPW.JPG


This resulted in the following acceleration charts for the respective Eagles in a full load. Note that the F-15Sx roughly matches the acceleration of the F-15C equipped with PW-100 motors in 97.7% trim.
Accelerations.JPG

Accelerations2.JPG


As a curiosity I "equipped" an F-15C with F110-GE-129 motors.
Super Eagle.JPG


I also matched up the accelerations of all currently serving U.S. 4th Gen fighters. All data is pulled from the manuals.
Acceleration comparison.JPG
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basher54321

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Unread post22 Aug 2017, 21:56

Nice work

We just need the F-16E manual now to put it back on top of the Accel charts :)
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Unread post23 Aug 2017, 03:00

This is awesome, is it possible for you to add the Su-35 or F-35 in and extended the subsonic part?
viewtopic.php?f=55&t=52510&start=75
I found this from a Chinese forum
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sprstdlyscottsmn

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Unread post23 Aug 2017, 04:02

I don't want to add anything that is pure guesswork. We have no data on the actual performance of the Su-35 and I have not made an updated performance sheet for the F-35. I also can't extend into the subsonic as the Eagle charts start at 0.83. the Hornet charts start pretty high too.
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chucky2

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Unread post30 Aug 2017, 17:28

So given the age of the F-15C/D fleet, and the performance of the F-15E (supposedly with the CFT installed), couldn't they just remove the CFT from the -E and fly them as F-15D? A CFT'less F-15E, APG-82, Sniper ATP, ought to be at least the performance equal to a F-15D in the air, should it not?

The F-15E strike role could just be performed by F-35A...it's not like F-15E is going to survive modern IADS anyways (well, while they're still up)...
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sferrin

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Unread post30 Aug 2017, 17:41

eloise wrote:This is awesome, is it possible for you to add the Su-35 or F-35 in and extended the subsonic part?
viewtopic.php?f=55&t=52510&start=75
I found this from a Chinese forum
Image


I have a tough time buying the Mig-29 and F-22 lines.
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disconnectedradical

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Unread post31 Aug 2017, 00:25

That F-22 line is nonsense, it accelerates from Mach 0.8-1.5 at 30,000 ft in about 52 seconds, just go check the 2010 SAR.

While Andraxxus on Key Pubs is pretty knowledgeable he makes a number of mistakes when analyzing the F-22, namely in that he kept insisting that it has a pitot inlet comparable to the F-16, when in reality the F-22 actually has an external compression inlet with oblique shocks, which allows the inlet supersonic pressure recovery to be much better than what the F-16 can do.
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Unread post31 Aug 2017, 09:54

sferrin wrote:
eloise wrote:This is awesome, is it possible for you to add the Su-35 or F-35 in and extended the subsonic part?
viewtopic.php?f=55&t=52510&start=75
I found this from a Chinese forum
Image


I have a tough time buying the Mig-29 and F-22 lines.


You can safely swap them.
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swiss

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Unread post31 Aug 2017, 19:37

Thank you. :D Very interesting.

sprstdlyscottsmn wrote:I don't want to add anything that is pure guesswork. We have no data on the actual performance of the Su-35 and I have not made an updated performance sheet for the F-35. I also can't extend into the subsonic as the Eagle charts start at 0.83. the Hornet charts start pretty high too.


Possible with EF and Rafale?
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sprstdlyscottsmn

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Unread post31 Aug 2017, 19:45

swiss wrote:Thank you. :D Very interesting.

sprstdlyscottsmn wrote:I don't want to add anything that is pure guesswork. We have no data on the actual performance of the Su-35 and I have not made an updated performance sheet for the F-35. I also can't extend into the subsonic as the Eagle charts start at 0.83. the Hornet charts start pretty high too.


Possible with EF and Rafale?

As of now I don't have any data for those two.
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Unread post01 Sep 2017, 13:02

How 'bout an F-15C with the 36,500lb thrust F100-232 or F110-132? (The -232 was actually run at 37,150lbs and the -132 at 36,500lbs. Both back in the 90s.)
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sprstdlyscottsmn

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Unread post01 Sep 2017, 13:52

sferrin wrote:How 'bout an F-15C with the 36,500lb thrust F100-232 or F110-132? (The -232 was actually run at 37,150lbs and the -132 at 36,500lbs. Both back in the 90s.)

Those are static, un-installed, test bench numbers. The thrust values I derived here are actual installed engines being run from ~0.8M to ~2.3M at 40,000ft, and even then I am only looking at EXCESS thrust, not TOTAL thrust. After all, the -129 and -229 engine bench almost identical thrust numbers, yet the -129 has significant superior excess thrust in the mid-Mach range especially when installed in a single engine fighter. I have other analyses I do where I make theoretical engine performance models, but this analysis was only using installed engines over a specific regime.
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Unread post01 Sep 2017, 14:14

sprstdlyscottsmn wrote:
sferrin wrote:How 'bout an F-15C with the 36,500lb thrust F100-232 or F110-132? (The -232 was actually run at 37,150lbs and the -132 at 36,500lbs. Both back in the 90s.)

Those are static, un-installed, test bench numbers.


Obviously, as are all other published numbers. Regardless, a bench value of 36,500lbs is going to translate to an installed value significantly higher than a bench value of 23,000lbs.
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Unread post01 Sep 2017, 14:17

Great work sprstdlyscottsmn. I love this stuff. The Eagle, dear to my heart, is a beast. Those engines and low wave drag make for world-class performance, even now :devil:
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Unread post01 Sep 2017, 16:54

sferrin wrote:How 'bout an F-15C with the 36,500lb thrust F100-232 or F110-132? (The -232 was actually run at 37,150lbs and the -132 at 36,500lbs. Both back in the 90s.)


Even if those weren't available, it would have been cool if the Saudi's had funded F110-GE-132 which already exists when they ordered their F-15SA. They had to reportedly re-certify it anyways due to the full FbW, could have just taken care of the upgrade right there. It ain't like they don't have the $$$...
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