Sorry FlyboyJ but you're post was far more ridiculous than mine, which had quite a bit of background to it.
They YF-12 was canceled because there simply wasn't a threat for it to intercept. It was impractical but did assist in the development of the Phoenix missile system. The F-15 was developed under a whole different military doctrine nearly a decade later. The USAF didn't go with the F-15 in lieu of the YF-12, that's plain nonsense!!!
The YF-12A was cancelled because of mission complexity and overall cost. As described by an A12 CIA pilot who was carried over to the SR71 programme in his book, Blackbird (to paraphrase), "...the problem with the YF-12 interceptor was that every Blackbird mission required the support of a NASA ground station identical to that used in its space launches. In all respects flying the Blackbird is far more like a space mission than flying an aircraft."
But you're right about the missile system, the AIM-47 SARH and advanced radar package comprised the Pheonix weapon system, the 90 mile range missiles available initially in nuclear tipped and conventional warheads. These were further developed to the AIM-54 ARH when the entire package was salvaged by the Tomcat in an attempt to recover development costs.
The F-15 will turn out to be one of the most cost effective weapons platforms when it is finally retired.
But not when it was intially developed. It was the single most expensive front line fighter of its day.
NOW THAT'S A JOKE! Are you sure you don't mean the SU-27???? The Mig-31 has a big powerful radar that could still be jammed, flies real fast and carries BIG missiles. BIG DEAL! Other than that it's a pig! It's still built out of steel, it cannot maneuver out of it's own way, has a 600 hour engine, drinks fuel like a whale, has a turning radius comparible to an SR-71 and is (was) a logistical nightmare. There was no big secret during it's development. Why do you think the Russians and other former USSR nations have gotten rid of their MiG-31s? It's a brick with wings! I think just about any modern western fighter (F-15, F-16, Tornado, F-18 ) if deployed properly, will feast on the Mig-31 without mercy!
I think it's fun dispelling comic book misconceptions.
The airframe of the MiG 31 is 50% high temp. nickle steel, 16% titanium and 33% indeterminent light alloys. Radome and wing spars are composite.
The construction is inherently stronger than the F-15's alloy and titanium ribbed, composite construction and aluminium honeycomb sections, which is designed for high transonic performance and excellent manoeuvrability as a dogfighter (something which had been continually stressed by F-4 pilots during Vietnam). The Strike Eagle involved a reinforcing of the overall structure to sustain high g's under heavy subsonic loading.
The high-supersonic g rating of the Foxhound is 5g's. The SR-71 is 1.5g's. The SR-71 is limited to a 45 degree turn rate at high supersonic speeds, a restriction the entire MiG 25 series does not have.
All MiG 25s (including the MP Foxhound or MiG 31), were designed for high manoeuvrability and overall rigidity at high Mach speeds. Put simply the best way to achieve this is with a good old fashioned solid construction.
What they can't do is a sudden wing over, split-s and immelman at transonic speeds (Mach 0.85 to 1.2), quite like honeycomb/composite structure US fighters can. What it can do is manoeuvre far more erratically at high supersonic speeds (Mach 2.3 and up), than any other fighter in the world and it has a fully loaded combat radius of over 700km on internal fuel, at that speed (1200km otherwise). Since they don't tow a refuelling tanker behind them into combat, they obviously don't guzzle juice too badly.
Bench testing of the Aviadvigatel D-30F-6 four stage augumention engines has surpassed several hundred thousand flying hours without breakdown (source: Jane's Information Group), as compared to the 1,000hr engine life of the MiG-25PD Tumansky engines. To my knowledge, a D-30F-6 engine has yet to fail under any conditions.
The rated maximum cruise of Mach 2.83 at 67,500 feet is geared for minimum augumented fuel consumption which provides the 34,170lbs st. the engine is nominally rated to this speed at. However these engines are designed to be oversped to 41,843lbs st. rated total maximum thrust, whereas the Tumanksys although sharing this inherent overspeed feature due to application, were not and this was the cause of the earlier Foxbat's infamous unreliability.
The avionics and full ECM package of the MiG 31 contains an electronically scanned phase array "Flash Dance" radar (digital multimode pulse doppler with lookdown shootdown equivalent), with a 200km search range, the ability to track 10 targets at 120km and engage up to four, simultaneously. This radar is so sophisticated it is able to track targets below and immediately behind the aircraft for a limited over the shoulder weapons fire capability and totally outclasses all other combat radar systems in service at the time of its inception.
Its primary weapon system is comparable to the Pheonix and although in early R-33 variants SARH (roughly equivalent to the original Pheonix AIM-47 missiles), later generation R-77, R-27 and R-33 variants are available in ARH configuration (roughly equivalent to Pheonix AIM-54 if this model has become available and AIM-120 AMRAAM class missiles, although the R-77 early production models have a bad rep).
As usual with Soviet later generation aircraft a full IR search/track system is fitted standard, a retractable sensor in this case.
"Other nations," former Soviet territories or otherwise haven't gotten rid of their MiG-31's, nobody else had any (edit to add: you reminded me in another post, China recieved a small number of early build MiG-25MP/MiG31's, quite right and my error of memory), the Russian Federation have kept their relatively few number in service (less than 200 were ever made). In fact the former "White Russia," ie. the Ukraine has kept its original MiG-25PD/PDS and RB Foxbats in service alongside the excellent Tu-22M medium bomber, MiG-23 Floggers and early Fulcrum A's. The problem however being that the limited Tumansky engine life of the earlier Foxbats and subsequent maintainence costs meant they were flown so infrequently that, believe it or not when the Ukraine became independant, nobody actually knew how to fly them! The Ukraine, India and China however all presently keep perfectly combat ready Foxbats, with India earmarked for Foxhound import (edit to add: as at around 2000).
Russia has been promoting the export of the early MiG-31 "Foxhound A" (the MiG-25MP), since the inception of the improved MiG-31M which is now the standard front line variant. More than 160 "first generation" Foxhound A's were delivered and an ASAT (anti-satellite), version has been created in the hope to increase the attractability of this inherently expensive aircraft in the wake of inexpensive Sukhoi and Fulcrum popularity.
I understand the MiG-31M is also being offered for export in its existing configuration, which is a move that mirrors the intial production of the Foxbats in the 70's, as they are designed to be employed only in small numbers with a much larger force of (detuned in the case of foreign exports) counter-air fighters.
The F-15 enjoys similar infrastructure restrictions, requiring elaborate, expensive and specialised ground support and maintainence schedules, and a large, well surfaced runway with a good takeoff run. Look I love aircraft and the F-15 is a goddamn awesome one, but reality is reality.
Vipers are therefore used in front line airfields and a strategy of inexpensive multirole, quick turnaround and easily manufactured numbers (with high parts commonality), is employed to take greatest advantage of these inherent operational "logistics."
Put simply, the US military infrastructure is the wealthiest in the world, and if it had Mikoyan instead of McDonnell Douglas it'd be using Foxhounds just like it uses F-15s and in those numbers. It'd be replacing Foxbat early variants for Foxhound later ones just as if they were F-15A's being superceded by F-15C's and equipping Flankers and Platypii as if they were Strike Eagles. The F-15 hasn't been
the cutting edge front line fighter because it's just well...so universally amazing a real philosophers stone, it is because the US is
rich. There is no other reason.
And when you are
rich you can afford to lay out untold billions in strategic "role to model outlay" and wait 35 years for it to come good on its investment financially. The Soviet Union tried it with the Flanker, Fulcrum and Foxhound team and broke their economy, now you can buy a new Su-27 cheaper than you'll get an F-15C with 3500 flying hours, you'll probably get an export Foxhound cheaper than you'll get a used Strike Eagle (you've been selling these to the Bin Ladens by the way, you naughty Americans). And Fulcrums are the European and Asiatic export competitor for Vipers.
The 1991 MiG-31M is did not fail to be the most advanced frontline fighter in the world at that time (to be superceded by the F/A-22), because it was incapable. It did because Russia is
poor. Put it in similar numbers to the F-15C all over Frontal Aviation and I suspect the universal threat evaluation of this aircraft would more than have impacted any uneducated assumptions of its mediocrity.
Like all the final series of production aircraft in the former USSR, the Foxhound, Fulcrum and Flanker series are tremendously underrated even by many fighter enthusiasts which are not closely familiar with the these models. This holds true for the excellent Su-34 anti-armour attack aircraft in the Warthog class to the high performing Tu-160 strategic bomber (which is a lot like a Concorde...with nukes), and the Tu-22M maritime-recon and medium bomber in the B1-B class (only much better performing).
The last of the Soviet fighters are dirt cheap because the CIS is broke, not because evenly matched for type and number they aren't perfectly capable of dominating a modern battlefield. The former Soviet Union desintegrated its economy building them to compete with the best US design prototypes, not failing to. Relatively few celebrated democratic nations are buying them because of existing support infrastructure and politics, not because US fighters are inherently better.
Seriously FlyboyJ, I'm surprised at your apparent ignorance in this matter.
As for the reasons behind the F-15's initial development it will require another elaborate post unto itself. If you're unsatisfied with my assertion that it was directly conceived to combat the Foxbat in lieu of the overpriced and unrealistic YF-12A proposal, I'll get around to it presently.