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Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2019, 06:18
by sprstdlyscottsmn
Only one VAB and it is a calculation hog. Double linear interpolation to take a 17X10 table and explode it to a 271X81 table for three difference parameters.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 19 Jan 2019, 07:51
by SpudmanWP
lol.. VBA, not VAB... my bad (damn you fingers). :doh:

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 01:33
by eloise
@Spurt: How many missile can F-15 carry before it has lower top speed and longer acceleration time than F-35?
Can a fully loaded F-15X with 16-22 AIM-120 catch a F-35?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 01:57
by SpudmanWP
Don't forget to add range into the question. If the F-15X is in full AB and the F-35 is not then how long will the AB fuel last?

How is it supposed to detect the F-35 at that range?

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 03:24
by element1loop
SpudmanWP wrote:Don't forget to add range into the question. If the F-15X is in full AB and the F-35 is not then how long will the AB fuel last? How is it supposed to detect the F-35 at that range?


It's reasonable to presume a networked F-15X in a modern force would be cued to the approximate location and vector of the F-35. Same is true of an F-35 though, and then some, and who could resist a snap J-turn to fire a slammer (or four) at the F-15X? The F-35 is either going to get a kill or make the F-15X turn and run. While the F-35A would be unlikely to need to run away from an F-15X (when a 4th gen meets a 5th gen 'n all). Then again, neither would be alone either.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 07:28
by eloise
SpudmanWP wrote:How is it supposed to detect the F-35 at that range?

Iam thinking F-15 can use MSDN and SACM to intercept F-35's missiles, then chase down the F-35 without wweapon

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 08:55
by SpudmanWP
SACM never claimed anti-missile capability and radar is useless vs the F-35 at anything longer than a few dozen miles.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 11:14
by eloise
SpudmanWP wrote:SACM never claimed anti-missile capability and radar is useless vs the F-35 at anything longer than a few dozen miles.

How about mixing MSDN and AIM-9X, F-15X use MSDN to intercept AIM-120 and SACM from F-35, then when F-35 is empty, it can be run down
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Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 14:36
by sprstdlyscottsmn
eloise wrote: then when F-35 is empty, it can be run down

Still have to find it first

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 14:46
by hornetfinn
sprstdlyscottsmn wrote:
eloise wrote: then when F-35 is empty, it can be run down

Still have to find it first


While not being killed by other F-35s in the area watching you closely...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 14:54
by marsavian
sprstdlyscottsmn wrote:
eloise wrote: then when F-35 is empty, it can be run down

Still have to find it first


Legion IRST21 pods with a bit of luck plus the latest EPAWSS might give it a clue where to look.

https://www.baesystems.com/en/product/e ... tem-epawss

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 15:22
by sprstdlyscottsmn
meanwhile, the F-35 and everything it is networked to already knows where you are and what you are doing. It's just not something I would want to do.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 15:33
by sprstdlyscottsmn
eloise wrote:@Spurt: How many missile can F-15 carry before it has lower top speed and longer acceleration time than F-35?
Can a fully loaded F-15X with 16-22 AIM-120 catch a F-35?

By my model (and I have a fairly high confidence in this model) an F-15SA with 14 AMRAAMS and two AIM-9Xs with CFT only has a top aerodynamic speed of ~1.59M. With 60% fuel, it would take 54s to reach Mach 1.2 from 0.8 at 30,000ft and using 1,280lb of fuel to do it. It would have 3 minutes of AB time remaining under these conditions before nominal BINGO (3* reserve remaining).

Weighing in at 60,580lb, it has a Wing Loading of 99.6, and Lift Loading of 60.8, a remaining Fuel Fraction of 0.22, and an excess thrust to weight at 0.85M@36,000ft of 0.18. That T/W correlates to a 10 deg climb or an acceleration of 3.4kt/sec or 0.006M/sec. There is a lot of power in two F100-GE-129s.

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 16:48
by quicksilver
spr, :salute: the work that has gone into your model. fwiw, it seems to be very generous wrt transonic accel in that configuration. Maybe the delta to my understanding is about the engines...

Re: Operational Performace Comparison: Viper, Beagle, and St

Unread postPosted: 08 Feb 2019, 16:57
by quicksilver
The other general observation I offer is that there is an opportunity cost in ‘catching’ or ‘running someone down’. Your fuel numbers highlight the fact that depending on where a given target is located relative to the weapons envelope of those weapons remaining on one’s jet, ‘running someone down’ can cost one the fuel to get home (or at least back to the tanker). Of course, if one is defending one’s home plate, ‘allowable risk’ for such decisions is very very high; in other cases, not so much.

Perhaps another relevant comparison might be the delta Mach necessary to close a given distance in a certain amount of time, because that helps define that ‘opportunity cost’ I refer to.