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The F-15 Eagle: Origins and Development, 1964-1972 [pdf]

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Re: The F-15 Eagle: Origins and Development, 1964-1972 [pdf]

#101

Post by greedo »

cpgxiii wrote: post #96
greedo wrote: post #84

Earlier quoted context omitted.

The USN didn't need an air-superiority fighter when they were working on the F-111B, they needed a fleet defense fighter capable of lifting a huge radar and missile set. When the terrible engines in the B model gave them an out, they took it and moved forward with the Tomcat (which used the same engines and weapons set). Little did they realize the TF-30 would remain a terrible engine for so long, and replacing it wi…

The engines certainly gave the USN the out it wanted, but the thing that truly killed the F-111B was the need for a dogfight-capable fleet fighter. There was no way they could have afforded two separate fighter development programs at the time, and Grumman had just the design they wanted ready to jump to. The NATF program probably would have worked out fine, albeit expensively. There has always been speculation that…

Regarding the Sea Apache, it really would have been a huge redesign. Deleting the 30mm Chain Gun, moving the landing gear to the wing stubs, adding a nose mounted radar, and Harpoon/Sidewinder capability. Now some of these requirements were Navy specific, but some would have been required had it been selected just for the USMC.

I think that even an unmodified Apache would have been just too expensive for the always cash-strapped Corps. Plus the airframe and engine commonality with the UH1s they flew simplified their logistics tremendously. It's always a gamble comparing unit costs since so much is either hidden or excluded, but the latest info I found showed a new build AH-1Z was around $30M in 2018, while a new build AH-64 is currently around $52M. And I'm pretty sure the Corp has simply been rebuilding older airframes to the new "Viper" standard. (Turns out most were rebuilds, but some were new construction.)

Regarding the RN flying Apaches, is this from large decked ships, or from anything with a pad? I know the Merlin had a neat winch type thing to help it land in bad weather, and I just wonder how much more likely a rollover would be on a small decked ship versus something like HMS Ocean etc.

Re: The F-15 Eagle: Origins and Development, 1964-1972 [pdf]

#102

Post by the__alchemist »

greedo wrote: post #86
tomohawk wrote: post #16

Earlier quoted context omitted.

It's more like the F35 over promises and under delivers compared to what it is expected to replace. The F15 comes with a 20,000 hour airframe, while the F35 comes with a 8000 hour airframe. The F15 can get to target much faster, much farther, and still have fuel to do something when it gets there. The F15 can carry 12 AIM-120s (or 24 depending), while the F35 can carry 4. The F15's a great interceptor. The F35 is a g…

You try flying an F-15 with 12 to 24 Slammers (and bags since you'll have so much drag. That's going to fly like a pig. Just because Boeing does some demo of it to sell more airframes doesn't mean it's going to be used that way.

Could go for those quad MRM packs though. Easier than 7 GBU-31s right.

Re: The F-15 Eagle: Origins and Development, 1964-1972 [pdf]

#103

Post by bee_rider »

kevbin wrote: post #91
zokier wrote: post #89

Earlier quoted context omitted.

And F-15 had its first flight four years before the MiG-25 defection. So unless they had time machine at hand its unlikely that it had major influence on F-15 design

My impression is the Westerners’ best guess about the Mig-25 contributed significantly to the design of the F-15 and helped to make it what it is. Getting their hands on it was a relief, or even a let down. The alternative scenario, where the Mig-25 really was generations ahead, plays out in the movie Firefox from 1982 where the US is so far behind they have to steal a Soviet Mig-31 superplane. Good for laugh today,…

The, probably slightly played up, version I heard is that the US saw the propaganda version of the Mig-25, and so built the F-15 to counter that imaginary beast.

Re: The F-15 Eagle: Origins and Development, 1964-1972 [pdf]

#104

Post by smcameron »

chiph wrote: post #10

For those of you using CA Harvest Software Change Manager, it has it's origins with Hughes Aircraft and the software written for the F-15. It was sold commercially as CCC/Harvest by Softool Corp starting in the late 1970's. Looks like Broadcom is the newest owner. It's still being used - the last time I encountered it was in 2009 at a large bank.

> CCC/Harvest

Now that's a name I've not heard in a long time. A long time.

(Was working at McDonnell Douglas at the time (mid 1990s), ISS related, had no idea about the F-15 connection. I do remember thinking CCC/Harvest seemed like a really strange choice at the time, but this F-15 connection... alright, so that's probably why.)

Re: The F-15 Eagle: Origins and Development, 1964-1972 [pdf]

#105

Post by cpgxiii »

greedo wrote: post #101
cpgxiii wrote: post #96

Earlier quoted context omitted.

The engines certainly gave the USN the out it wanted, but the thing that truly killed the F-111B was the need for a dogfight-capable fleet fighter. There was no way they could have afforded two separate fighter development programs at the time, and Grumman had just the design they wanted ready to jump to. The NATF program probably would have worked out fine, albeit expensively. There has always been speculation that…

Regarding the Sea Apache, it really would have been a huge redesign. Deleting the 30mm Chain Gun, moving the landing gear to the wing stubs, adding a nose mounted radar, and Harpoon/Sidewinder capability. Now some of these requirements were Navy specific, but some would have been required had it been selected just for the USMC. I think that even an unmodified Apache would have been just too expensive for the always c…

I think the Sea Apache design was doomed to failure, potentially deliberately, by including so many modifications to the base design. A reasonably scoped modification for the USMC would have been the standard increased corrosion resistance, folding main rotor, tail wheel moved forwards, and folding tail fin+rotor (i.e. all the same modifications made to the base S-70 design for shipboard use).

The cost question is a very tricky one, hence why I used the comparison of foreign orders between the two types as an assessment of overall value. My understanding is that more AH-1Z/UH-1Y airframes were new builds than was originally planned (hardly a surprise), which strongly suggests that airframe reuse did not save as much in production as hoped. The strongest argument for the AH-1Z cost-wise was the commonality with UH-1Y, but had the USMC considered switching entirely to AH-64 + SH-60 derivatives instead I don't think that argument would have been as strong (after all, the whole rest of the USN operates SH-60 variants, including the ships that operate USMC AH-1/UH-1s).

The RN has flown WAH-64s from their large deck ships, so roughly equivalent size-wise to anything that routinely operates AH-1Zs. The only important modification in the WAH-64 design is a folding rotor to reduce storage size, but that doesn't affect takeoff/landing abilities. With some minor changes like pulling the tail gear forwards (e.g. as on the {S,M}H-60{B,F,R}), you could fit an Apache on anything that can handle a Seahawk (i.e. basically everything with a pad). Notably, the AH-64 wheelbase is not that different from the spacing of the skids on an AH-1, so it's not going to be hugely different in terms of stability on a large deck ship. There's also been a fair number of training exercises between US army AH-64 units and USN ships, so shipboard Apache operations aren't exactly foreign to the US either.

Re: The F-15 Eagle: Origins and Development, 1964-1972 [pdf]

#106

Post by The_Colonel »

justinator wrote: post #99
The_Colonel wrote: post #70

I'm kind of fascinated how these deadly machines can be so good-looking / elegant.

I've worked at Wings Over the Rockies a bit, and they have an old F4. It's not good looking/elegant. It just looks like a bunch of giant metal cylinders welded onto each other that holds a lot of very explosive liquid with mounting points to put smaller cylinders on with more explosives. I get that the status quo has marketed fighter jets as sexy, but they just are there to do a job and that job is to kill.

I agree regarding the older jets like F-4. But e.g. F-15, F-22, MiG-29 or B-2/21 look great. Interestingly, the newer F-35 less so (it's a bit "chunky").

Re: The F-15 Eagle: Origins and Development, 1964-1972 [pdf]

#107

Post by VLM »

jki275 wrote: post #62
hef19898 wrote: post #57

Earlier quoted context omitted.

BVR engangements are happeneniing when the shooting side discovers the targeted side first. If they don't, it is visual range again. Obviously low observability aircraft, e.g. a F-35 or 22, have an advantage here. But then the other side can have AWACS to guide their attackers. And let's not forget, jets like a Rafale of Eurofighter, or even a F/A-18, have smaller radar signatures than a F-15. An once the stealth air…

The F4 didn't have a cannon, but the real problem in Vietnam was bad missiles, not lack of a gun, and the massive improvements in missile technology were what made the Phantom effective. A gun is almost utterly useless in modern fighter aircraft, especially for air to air engagements, especially in a world where the AIM-9X and its opposing side equivalents exist. You will never, even WVR, even if you graduated TOPGUN…

We just spent 20 years using guns for close air support, wouldn't call that useless.

The problem with BVR is there's zero room for risk and zero room for error and BVR missiles are pretty random/shotgun weapons. If BVR missiles are only effective 1/3 of the time you're better off going non-BVR and using your logistical might to put 3x the number of planes in the air...

Re: The F-15 Eagle: Origins and Development, 1964-1972 [pdf]

#108

Post by mhh__ »

The_Colonel wrote: post #106
justinator wrote: post #99

Earlier quoted context omitted.

I've worked at Wings Over the Rockies a bit, and they have an old F4. It's not good looking/elegant. It just looks like a bunch of giant metal cylinders welded onto each other that holds a lot of very explosive liquid with mounting points to put smaller cylinders on with more explosives. I get that the status quo has marketed fighter jets as sexy, but they just are there to do a job and that job is to kill.

I agree regarding the older jets like F-4. But e.g. F-15, F-22, MiG-29 or B-2/21 look great. Interestingly, the newer F-35 less so (it's a bit "chunky").

Hence "Fat Amy" for the F-35

Re: The F-15 Eagle: Origins and Development, 1964-1972 [pdf]

#109

Post by indymike »

cpgxiii wrote: post #63
indymike wrote: post #56

Earlier quoted context omitted.

> This whole "multi-service aircraft can't work" meme has been going for essentially a century, and has been wrong just as long. I'm not sure that's really the case. When we see successful cross-service adoption, it's because the aircraft simply was that so good the other branch saw a lot of value in buying it. So far the only program that has worked from inception is the F-35. The others failed to get traction in th…

My point is that multi-service aircraft are entirely possible, and have been all along. That several notable aircraft emerged as multi-service aircraft is all the more evidence that a multi-service aircraft (really, a family of tightly related aircraft) can be designed as such. The reason there are more USN->USAF success stories is that it is much easier to design an aircraft with the stresses of carrier operation in…

> The USAF and USN are just incredibly unwilling to have to compromise

I don't think that is the case. The issue is that most of the joint programs fail because they start with such a broad difference in requirements the program can't work. Here are two examples:

F-111/TFX - Navy wanted a fleet interceptor / air superiority fighter built around the Phoenix Missile. Air Force wanted a heavy attack aircraft. The F-111 led to the Navy having to do a crash development to get the F-14 Tomcat.

F-16 LWF - Navy wanted a twin engine. AF wanted single engine. Joint program died immediately... so we the taxpayers ended up with the USAF buying F-16 (great aircraft) and the Navy ordering an update on the YF-17 which became the F/A-18 Hornet (another great aircraft). Incidentally, the YF-17 was a twin engine iteration of the F-5 (which is an iteration of the T-38 Talon), and the F/A-18 is an iteration of the YF-17.

> for most of the cold war had the budgets and supplier diversity to acquire entirely separately.

I think you are on to something: lack of supplier diversity will be a forcing function in the future...

Re: The F-15 Eagle: Origins and Development, 1964-1972 [pdf]

#110

Post by cpgxiii »

indymike wrote: post #109
cpgxiii wrote: post #63

Earlier quoted context omitted.

My point is that multi-service aircraft are entirely possible, and have been all along. That several notable aircraft emerged as multi-service aircraft is all the more evidence that a multi-service aircraft (really, a family of tightly related aircraft) can be designed as such. The reason there are more USN->USAF success stories is that it is much easier to design an aircraft with the stresses of carrier operation in…

> The USAF and USN are just incredibly unwilling to have to compromise I don't think that is the case. The issue is that most of the joint programs fail because they start with such a broad difference in requirements the program can't work. Here are two examples: F-111/TFX - Navy wanted a fleet interceptor / air superiority fighter built around the Phoenix Missile. Air Force wanted a heavy attack aircraft. The F-111…

> The issue is that most of the joint programs fail because they start with such a broad difference in requirements the program can't work.

Agreeing on requirements is the most important compromise. You can always come up with different requirements that make collaboration impossible. Sometimes these differing requirements are fundamental - e.g. the E-2 and E-3 (E-7 in the future), while performing similar roles, are necessarily very different platforms - that a joint program would never be considered. Sometimes these requirements are not so fundamental - e.g. the many years of single-engine versus twin-engine disagreement - that a joint program is possible, albeit challenging.

While the JSF program has had plenty of issues, the fact that it has been successful in delivering the envisioned aircraft is a testament to (a) technology improving to the point that many once-dealbreaker requirements (e.g. single-engine) could be swept aside, (b) the rise in costs making it clear that completely separate development programs were impractical, and (c) explicitly providing requirements flexibility via the "family-of-aircraft" approach (no way the F-35C would have been acceptable financially to anyone other than the USN, no way the F-35A would have been suitable for carrier use).

> ...lack of supplier diversity will be a forcing function in the future...

The consolidation of the 90s and 2000s is directly the consequence of lower budgets. Consider the fighter/strike fleets of the 1980s:

- USAF: A-7 (LTV), A-10 (FR), F-4 (MD), F-15 (MD), F-16 (GD), F-111 (GD), F-117 (Lockheed)

- USN: A-6 (Grumman), A-7 (LTV), F-4 (MD), F-14 (Grumman), F/A-18 (MD)

versus today:

- USAF: A-10 (none), F-15 (Boeing), F-15E (Boeing), F-16 (LM), F-22 (LM), F-35A (LM)

- USN: F/A-18E/F (Boeing), F-35C (LM)

there's just not enough business to support much more than the Boeing/LM duopoly keeping both production/support running and enough capability to be competitive for the NGAD programs.

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