If the F-111 never happened... Done!

[Spino]

Well, this one built up rather nicely.  Will post most of the photos when I get the backstory finished (there are a lot of them).  For now, here's a sample...

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Yes, today was a marathon of a build day!  This morning the model looked pretty much exactly like it did in the last photo I posted.

[chrisonord]

Very nice 

[Spino]

Thankfully the canopy was relatively easy to get right, unlike the Convair canopy that I'm still having trouble with 

The GBU-8s had relatively thin fins, but otherwise turned out okay.  I managed to find a model of an LAU-105 and printed it up for the Sidewinders to mount on.  The drop tanks got culled because I ran out of khaki paint, but that simplified mounting of the Sidewinders and the ECM pod.

[Spino]

Took me long enough, but I finally finished the backstory on the F-107E.  So here it is, photos and all:

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Mounting issues with the F-105 procurement program (largely due to the Cook-Cragie manufacturing methods used for that aircraft) caused the US Air Force to reconsider the NAA F-107 for the low-altitude tactical nuclear strike role.  The F-107's design, while not ideal for low-level missions, was a more well-rounded aircraft than the F-105, and could operate from unprepared airstrips thanks to its strong landing gear.  Additionally, its top-mounted intakes minimized the potential for FOD ingestion.  The F-107A, named "Sabre II" was ordered into production in May 1960, with the first squadrons receiving their aircraft in November of that year.  The F-107 quickly proved to be entirely capable of the low-level nuclear strike mission, albeit somewhat less well-suited than the more specialized F-105.  The improved F-107B and D variants were used heavily during Operation Rolling Thunder, sustaining significant losses to ground fire (in large part due to the insanity of the repeated mission profiles that the F-107 crews were forced to use), but it proved to be a tough airplane capable of taking punishment and dishing it back out.  The single greatest issue with the F-107 proved to be its dogfighting capability, or rather lack thereof.  While possessing a lower wing loading than its competitor, the F-105, the F-107's top-mounted intake was easily blanked at higher angles of attack, resulting in loss of thrust and potentially engine flame-out.  This put the F-107 at a disadvantage most of the time against VPAF MiGs, though if the F-107 pilot cold get a MiG in his sights the four 20mm cannon were more than capable of shredding the enemy aircraft.

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With the F-4 Phantom II being pressed into both the ground attack and fighter roles with USAF, the F-107 began to take a back seat in the air war over Vietnam, and there was talk of retiring the remainder of the fleet.  However, the replacement for the F-107 (the F-111) became bogged down in technical difficulties and cost overruns, resulting in a need for an improved tactical strike aircraft.  After an improved variant of the A-5 Vigilante was rejected by USAF brass still smarting from having the F-4 forced on them, NAA proposed an upgrade to the existing F-107 fleet.  This upgrade replaced the J-75 turbojet with an improved variant of the F401 being developed for the Convair F/A-17 Kestrel and Grumman F-14 Tomcat, added a new radar with terrain following modes, all-round improved avionics, and the ability to carry a Pave Tack targeting pod in place of the semi-conformal special store.  This upgrade was relatively inexpensive compared to the other options available to the Air Force, so some 300 remaining F-107Ds were re-manufactured to the new F-107E standard. 

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The rebuilt aircraft proved to be a significant upgrade over the previous F-107 variants.  The new turbofan increased range by more than 20% while providing significantly more thrust than the old J-75, while the revolutionary new avionics allowed the single pilot to effectively manage both the aircraft and its weapons systems, even in a high-threat environment.  The adoption of this new F-107 variant resulted in a change in USAF tactical doctrine, with F-107s being based at austere airstrips close to potential hot zones.  This was primarily because even with the new engine, the F-107 simply could not match the range of the F-111.  However, with its further strengthened landing gear and top-mounted intake, the Sabre II was very well-suited to this relatively new basing strategy, and provided more quick-reaction aerial firepower to NATO than the smaller Harriers. The Pave Tack pod combined with Paveway LGBs allowed the F-107 to engage ground targets with pinpoint accuracy.  While commonly referred to as "Pave Drag" by F-4 crews who were forced to give up a weapons station to carry that pod, the F-107's belly recess that had once carried a nuclear weapon proved to be an excellent alternative; the semi-conformal mount considerably reduced the added drag of the pod and resulted in essentially no difference in the real-world top speed of the F-107 (Mach 1.3 with a typical strike load).

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F-107s were deployed from RAF Akrotiri in 1986 for Operation El Dorado Canyon, dropping precision bombs on multiple targets in Libya.  While no F-107s were directly shot down in the raid, one suffered an engine flame-out while evading an SA-6 and crashed in the Mediterranean.  F-107s also participated in Operation Desert Storm, dropping roughly 70% of the laser-guided bombs used in that conflict.  One even shot down an Iraqi MiG-23 whose pilot mistakenly took an un-escorted F-107 flight for easy pickings – the Sabre IIs had already dropped their bombs and thus were just maneuverable enough to turn the tables on the MiG and destroy it with cannon fire.  F-107s remained in service until the mid-1990s, when they were replaced with F-15E Strike Eagles.

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Specifications (F-107E):

    Crew: one
    Length: 62ft 5in (19.02 m)
    Wingspan: 36 ft 7 in (11.15 m)
    Height: 19 ft 8 in (5.89 m)
    Wing area: 377 sq ft (35 m2)
    Empty weight: 22,696 lb (10,295 kg)
    Gross weight: 39,755 lb (18,033 kg)
    Max takeoff weight: 41,537 lb (18,841 kg)
    Powerplant: 1 × Pratt & Whitney F401-230 turbofan, 30,000lbf thrust
    Maximum speed: 1,295 mph (2,084 km/h, 1,125 kn, Mach 2 at altitude)
    Range: 2,938 mi
    Service ceiling: 53,200 ft (16,220 m)
    Rate of climb: 41,900 ft/min
    Wing loading: 106 lb/sq ft (516 kg/m2)
    Thrust/weight: 0.75

[Weaver]

Nice one Spino - looks good in that cammo. 

Begs the question of what the USAF would have replaced the F-111 with if it had been cancelled in the real world too, doesn't it?

[buzzbomb]

Nifty design and build from 3D parts.

FDM or resin for the printed parts ?

[Spino]

Nifty design and build from 3D parts.

FDM or resin for the printed parts ?

Thanks!  It's all FDM I'm afraid, I don't have a resin printer and it's not really in the budget right now.

[kerick]

That's a great looking F-107!

[chrisonord]

Very cool looking plane, and excellent build. 

[Spino]

Begs the question of what the USAF would have replaced the F-111 with if it had been cancelled in the real world too, doesn't it?

Indeed it does!  My vote would be for an improved version of the A-5 with the tunnel bay replaced by fuel tanks and improved ECM, and the J-79s swapped out for Speys, but after USAF got stuck with both the F-4 and the A-7 they probably wouldn't like that.  Maybe TSR-2 or a heavily upgraded B-58?

[Weaver]

Begs the question of what the USAF would have replaced the F-111 with if it had been cancelled in the real world too, doesn't it?

Indeed it does!  My vote would be for an improved version of the A-5 with the tunnel bay replaced by fuel tanks and improved ECM, and the J-79s swapped out for Speys, but after USAF got stuck with both the F-4 and the A-7 they probably wouldn't like that.  Maybe TSR-2 or a heavily upgraded B-58?

My suspicion is that, just like with the Navy, the F-111B and the Tomcat, they'd have started another programme from scratch for something uniquely tailored to their single-service requirement. That then begs the question of would it have been swing-wing or not? I suspect it would have come down to whether the F-111's problems were fundamental design concept issues, or the result of trying to fit USAF requirements into the USN's carrier operations limits.

[Spino]

Begs the question of what the USAF would have replaced the F-111 with if it had been cancelled in the real world too, doesn't it?

Indeed it does!  My vote would be for an improved version of the A-5 with the tunnel bay replaced by fuel tanks and improved ECM, and the J-79s swapped out for Speys, but after USAF got stuck with both the F-4 and the A-7 they probably wouldn't like that.  Maybe TSR-2 or a heavily upgraded B-58?

My suspicion is that, just like with the Navy, the F-111B and the Tomcat, they'd have started another programme from scratch for something uniquely tailored to their single-service requirement. That then begs the question of would it have been swing-wing or not? I suspect it would have come down to whether the F-111's problems were fundamental design concept issues, or the result of trying to fit USAF requirements into the USN's carrier operations limits.

If swing wings weren't necessary outside of the USN requirement, then the easiest option might have just been to develop the Strike Eagle about ten years earlier than it actually happened, and maybe keep the F-105s around a few more years until the mudhen gets into service in significant numbers.

[Weaver]

Begs the question of what the USAF would have replaced the F-111 with if it had been cancelled in the real world too, doesn't it?

Indeed it does!  My vote would be for an improved version of the A-5 with the tunnel bay replaced by fuel tanks and improved ECM, and the J-79s swapped out for Speys, but after USAF got stuck with both the F-4 and the A-7 they probably wouldn't like that.  Maybe TSR-2 or a heavily upgraded B-58?

My suspicion is that, just like with the Navy, the F-111B and the Tomcat, they'd have started another programme from scratch for something uniquely tailored to their single-service requirement. That then begs the question of would it have been swing-wing or not? I suspect it would have come down to whether the F-111's problems were fundamental design concept issues, or the result of trying to fit USAF requirements into the USN's carrier operations limits.

If swing wings weren't necessary outside of the USN requirement, then the easiest option might have just been to develop the Strike Eagle about ten years earlier than it actually happened, and maybe keep the F-105s around a few more years until the mudhen gets into service in significant numbers.

Hmm, dunno about that. If the F-111 was going to be cancelled at all, then it would have been in the late 1960s at the latest, and the F-15 was still a "paper plane" at that point, with it's entire raison d'etre being pure air-to-air, it's motto being "not a pound for air to ground" and it's principle cheerleaders being the "fighter mafia". I can't see them viewing Strike Eagle concepts as anything other than a threat at the time, and pushing back as hard as they could. They were already disturbed by how large the F-15A was turning out to be...

The F-105s were already on the way out by that point, with HUGE attrition in Vietnam and the F-4 able to do anything they could do. If they were going to develop an interim aircraft, it would most likely have been F-4-based, purely for lack of alternatives. One interesting possibility might be that they'd develop a quick'n'dirty "Strike Phantom" based on the UK's F-4K/M, who's Spey turbofan engines conferred greater range at the cost of some high-altutude performance. As a new-build aircraft, it might have structural strengthening and as many F-111 black boxes as were working by that point. RAF Phantoms had inertial navigation platforms, and a combination of small attack radar+terrain-following radar in the large "Navy" radome, in the style of the Tornado, doesn't seem unreasonable.

It doesn't neccessarily follow that removing the USN requirement removes the need for swing-wings. After all, the UK/Germany/Italy and the Soviet Union put purely land-based swing-wing strike aircraft into service for reasons of short field length, dispersal capability and reconciling long range with high attack speed. France looked seriously at it as well, to the point of building prototypes.

[Spino]

Good points, I forgot that the F-15 didn't even fly until 1972.

[HarryPhishnuts]

First of @Spino great work as always. I bow to your 3D prowess 

The core question of cancelling the F-111 really depends on timing. If it was early in the program say early 60's then the USAF would probably just start a new program. It it was later in the program, then the options become more interesting. The only real contemporary to the F-111 at that time was the TSR.2. For both their primary mission was fly real-low, real-fast, drop whatever fun sticks they had and run like hell, in all kinds of weather. The only other thing by late 60's that kinda fits that would be the Mirage IV but there's no way the USAF would consider a French aircraft. The Vigilante was too far out of production by that point but maybe some kind of new de-navalized, just for USAF, derivative could be an option. A "strike" centered F-4 could be possible but the issue would be range and on the deck speed. While you could find a different engine to help (Spey or maybe some derivative of the TF-30 assuming it had gotten far enough along) I'm not sure how well the F-4 could really do at true nap-of-the-earth mission profiles.

I mentioned on @Spino F-8 build but if they were looking for something really intermediate, Vought had a couple of supersonic attack Crusader ideas they had been kicking around in the 60s. Something like what would become the YA-7F but with an afterburner and de-navalized could be an option. Say combine it with the Spey-Sader proposal they did there might be something there. 

Lots of juicy ideas in this.