F-16 Radar Missile development (AIM-7)

[basher54321]

Also shows the AIM-7s with the 370 drop tanks installed when the pylons were located further outboard:

[F16VIPER]

Thank you for posting this historical video.
Great find.

[arian]

Why were the landing bay door hard-points dropped from production aircraft? Seems like a good idea.

[basher54321]

I take from what John Will has said:

There was no requirement for BVR missiles on the F-16 originally so little effort was put into mounting them on the fuselage. These mock up pylons were only for flight test firing of the AIM-7.

The YF only had 2 pylons on the wing and when they moved to 3 pylons the inner pylons (4/6) were moved closer in so the clearance for AIM-7s was no longer there anyway.

[madrat]

Looks rather roomy.

[basher54321]

I guess the clearance issue refers to having the gear down and drop tanks installed.

[basher54321]

Another one

[mixelflick]

Also shows the AIM-7s with the 370 drop tanks installed when the pylons were located further outboard:

Did I hear that correctly? Acceleration to mach 1.6 WITH sparrows? I know I heard mach 1.05 sparrow launch. If the former is correct, it makes me wonder about the F-35. One of its attributes is that it's able to hit mach 1.6 with a combat load/combat configured.

But if the video's correct, the F-16 did this in 1977? Granted, no 2,000lb bombs but still..

[basher54321]

Sounds like they tested it to M1.6 - if it was just 2 x AIM-7 and 2 x AIM-9 it could probably go faster. Not really a surprise, would think the F-4 for example and some other AIM-7 carriers could hit their top end with just AIM-7s (without knowing limitations on carriage). Not that top end is always realistic or a practical speed to ever be at but it could be done.

The big advantage is in the F-35 primary AG role where F-16 etc AG loadouts are subsonic / transonic only. F-35 (Internal Weapons & Fuel) can accelerate and cruise faster and higher - and still go to max speed at any point without having to jettison anything.

[vilters]

Hi guys, multiple things going on here.

a) the wing was changed to get more stations. This put the inner wet stations further inside, reducing clearance.
b) the landing gear doors are different.

On the prototypes the MLG has 2 small doors each side : One goes outwards, and the downwards opening door is hinged on the centerline. => The AIM-7 were mounted on the upper/outwards opening doors.

Production models went to a single outwards opening door/side.

[Meteor]

Sounds like they tested it to M1.6 - if it was just 2 x AIM-7 and 2 x AIM-9 it could probably go faster. Not really a surprise, would think the F-4 for example and some other AIM-7 carriers could hit their top end with just AIM-7s (without knowing limitations on carriage). Not that top end is always realistic or a practical speed to ever be at but it could be done.

The F-4C/D carrying 4 x AIM-7 was certified out to aircraft limits, which was Mach 2.5. The employment envelope was 220 KIAS to M2.5.

Unlike current fighters (F-15/16/18/22), earlier fighters were expected to jettison their external fuel tanks before entering combat. They tanks were cheap, flimsy, low G, and expendable. I remember whole fields full of crates of expendable F-4 fuel tanks at Incirlik and Kunsan. Thus it was not expected that Century series fighters would enter combat while still carrying their external tanks. The combat (non-training) air-to-air employment envelope was predicated on a no-tanks configuration.

Keeping a huge amount of bulky external tanks on hand while overseas was a logistics nightmare, especially on an aircraft carrier. There are numerous photos of carriers undergoing replenishment while at Yankee Station (Gulf of Tonkin), which show the transfer of crates of external tanks over to the carrier. The tanks also tended to be unreliable, precisely because they were not intended for extensive and repeated usage, and they had often sat outdoors for years before being mounted on a jet. It was decided that newer generation jets (F-15/16/18) would have higher quality, higher performance, and consequently higher priced external tanks that were expected to be retained through combat, and returned to the base for re-use.

When comparing performance figures of earlier jets (Mirage III, F-105, Mig-21) versus newer jets (SU-27, F-16, Rafale) assume that the earlier jets would hit the merge with only their air-to-air ordnance onboard, while the later generation jets would still be carrying their tanks.

[johnwill]

Hi guys, multiple things going on here.

a) the wing was changed to get more stations. This put the inner wet stations further inside, reducing clearance.
b) the landing gear doors are different.

On the prototypes the MLG has 2 small doors each side : One goes outwards, and the downwards opening door is hinged on the centerline. => The AIM-7 were mounted on the upper/outwards opening doors.

Production models went to a single outwards opening door/side.

Not true. YF-16 had one piece main gear doors. After LWF competition was complete, two piece doors were built to test AIM-7 and Skyflash. Nose gear had two piece doors that were changed to one piece for production.

[outlaw162]

The combat (non-training) air-to-air employment envelope was predicated on a no-tanks configuration.

Interesting statement, and somewhat telling.

The parenthetical (non-training) is significant as far as the Phantom was concerned. FOR TRAINING much of the F-4 A2A was done with wing tanks or a CL tank just to be able to get to and more importantly from the training airspace, which in many cases was subsonic anyway. Depended to some extent on the unit and the location, but AFRES (particularly Tinker & Homestead) always flew A2A 'clean' when the situation allowed. Missions were shorter (and the fuel-gauge was your primary instrument ) but more productive.

The Constant Peg program purported 'value' was overrated as far as the F-4 was concerned. You had to carry tanks to make it all the way around the west side of the airspace and back out the same way. So you really didn't get to fly the airplane the way you really would have to.....jettisoning the tanks would have been embarrassing and frowned upon at home. Other than intercepting and seeing 'one' or 'two' and realizing you were at a gross disadvantage, both 'g' & acceleration-wise with tanks on, you might as well have gone downtown to a casino where you could also lose, but had a better chance to win.

We found the best place to 'hone' how to fly the Phantom A2A was out of Yuma and used it often. 25 miles to the ACMI....and 25 miles back. Miramar guys appreciated the 'depressed angle radar' simulators that were pretty much forced to start off down low. (local Miramar Phantom reserve VFs, 301 & 302 had PD radars so not necessarily as useful for training against simulators of what the export threat had at the time)

In any case what a pleasure to get into a machine with the fuel specifics and other assorted capabilities of the Viper.....even without the vaunted AIM-7.

[basher54321]

The F-4C/D carrying 4 x AIM-7 was certified out to aircraft limits, which was Mach 2.5. The employment envelope was 220 KIAS to M2.5.

Unlike current fighters (F-15/16/18/22), earlier fighters were expected to jettison their external fuel tanks before entering combat. They tanks were cheap, flimsy, low G, and expendable. I remember whole fields full of crates of expendable F-4 fuel tanks at Incirlik and Kunsan. Thus it was not expected that Century series fighters would enter combat while still carrying their external tanks. The combat (non-training) air-to-air employment envelope was predicated on a no-tanks configuration.

Many thanks Meteor - I had read the F-4 needed to at least ditch the centreline tank to get clearance for firing the AIM-7 and the jettison speed was relatively low on the original tanks.

Was this wishful thinking on someones part then because I remember a good few F-15 pilots ditching their tanks pre merge in DS (via their own statements) - was thinking that was SOP but I suppose left to pilot intuition regardless of the extra cost they still significantly degrade a pilots survive-ability

[Meteor]

Many thanks Meteor - I had read the F-4 needed to at least ditch the centreline tank to get clearance for firing the AIM-7 and the jettison speed was relatively low on the original tanks.

Was this wishful thinking on someones part then because I remember a good few F-15 pilots ditching their tanks pre merge in DS (via their own statements) - was thinking that was SOP but I suppose left to pilot intuition regardless of the extra cost they still significantly degrade a pilots survive-ability

Just pulled out my old and yellowed F-4C/D-1 to check the numbers: The centerline 600 gallon tank was limited to 600KIAS/M1.8, while the wing 370 gallon tanks were between 550-750KIAS and M1.6 depending on whether they were empty or not. G limits for the centerline were 3-5G (depending on fuel), and the wing tanks were 4-6G. Max jettison speed for the CL was 425KIAS, and only up to 375KIAS (at 1G) for the wings.

The clean air-to-air (4 x AIM-7) airspeed limits were 750KIAS and M2.5. Below M.72 and 37,500LBS, the G limit was 8.5. Comparing the "with tank" versus "without tank" performance figures above, it's obvious why we jettisoned tanks prior to the merge. That's why our "real world combat" fence check had us jettisoning the tanks no later than 10 miles prior to the merge.

While I don't doubt that some aircraft jettisoned their tanks prior to an air-to-air fight in recent wars, I do not believe that it was encouraged. I vaguely remember a briefing (in 1983) when we switched from the F-4D to the F-16A at Torrejon AB. I'm making up these numbers (because I'm old and going senile), but as I recall they said that we had over 10 sets of tanks for every F-4 at TJ, but that the USAF was only buying 1.2 sets per F-16. (In other words, if you jettison them, you don't get another set.)

There is no free lunch when it comes to carrying more fuel. The F-22 and F-35 carry all of their fuel internally. That's a lot of internal volume. Lots of space inside means a larger, heavier, draggier jet. Large, heavy, draggy jets require more structure to support the weight under G, which requires more thrust to push through the air, which requires more fuel to accomplish, etc. It's a vicious circle. The USAF has decided that the advantages of stealth outweigh the costs of carrying all that fuel internally. I'm not privy to all of the studies, so I'm not going to argue with them.

Something to consider: An F-35A comes off the tanker with 17,000LBS of internal fuel. Shortly thereafter he commits to an air-to-air engagement, He arrives at the 10 mile point with 15,000LBS still onboard. He's going to carry all of that fuel into the engagement. He might prefer to enter the fight at a 50% fuel load (8,500LBS) but he doesn't have that option, because he can't rapidly jettison the fuel. He's going to be carrying an extra 6,500LBS (the equivalent of 3 x MK-84s) to the merge. I know that I would at least like to have the option of reducing my gross weight if I was entering a fight outnumbered and with only a couple of AIM-120s onboard.