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Flightline Friday – the Convair F-106 Delta Dart January 10, 2014

Posted by Tantumblogo in Admin, Flightline Friday, foolishness, fun, Society, technology.

Ah, this is one of my all time favorite birds.  I love the Delta Dart.  Conceived in 1954 as the “ultimate interceptor,” the F-106 endured a protracted development period that wound up seeing far more of its predecessor – the not nearly so ultimate Convair F-102 Delta Dagger – produced that the ultimate version.

The Delta Dagger and Dart brought a number of new technologies to fruition.  Convair was the prime American company that continued Dr. Alexander Lippisch’s experiments with triangular wing planforms in Nazi Germany.  After the war,

XF-92A prototype

XF-92A prototype

Convair produced the experimental XF-92 delta wing prototype.  Chuck Yeager did much of the early testing on this aircraft.  The aircraft was underpowered, but showed some promise, so the Air Force gave Convair a contract to develop a new, delta-wing interceptor.  That was supposed to be the 1954 ultimate interceptor, but problems in development led the Air Force to approve what was supposed to be an interim type.  That became the F-102, which had many problems of its own.

The -102 was supposed to be the Air Force’s first supersonic all-weather interceptor.  All previous interceptors – the F-89, F-94, and F-86D, were transonic at best.  In order for an interceptor to have a reasonable ability to respond to last minute threats, or even to overhaul a fleeing bomber, they need to have at least twice the top speed as the bomber.  So, these transonic interceptors with top speeds of 6-700 mph were really only good against propeller driven bombers.  They were obsolete against aircraft like the B-52, and even the prop+jet (6 turnin’ and 4 burnin’!) B-36 gave them a very hard time at high altitude.

Unfortunately for the Air Force and Convair, the prototype F-102 did not perform as expected. In fact, it was barely as fast as an F-86!  The problem turned out to be transonic drag.  While the J-57 powered F-102 had plenty of thrust, it’s aerodynamic design was such that the type could not go supersonic.  Fortunately for the Air Force and Convair, NASA’s brilliant aerodynamicist Richard Whitcomb had already discovered this problem and developed his solution of “area-ruling.”  Area ruling required an aircraft to have a fuselage that was fat in front and in back, but skinny in the middle – the so-called “wasp waist” or “coke bottle” shape.  See the photos below, to see how the F-102 changed from a uniform, thick fuselage, to one with some of Whitcomb’s characteristics.

Original F-102

Original F-102

Revised F-102A

Revised F-102A

It might not seem like much, but that change to fuselage shape increased the F-102A’s top speed by about 20%, to 825 mph.  This increase was all that could be achieved by modifying an already complete design. But that was still not nearly as fast as the Air Force needed – in order to counter suspected Soviet transonic (600 mph) bombers, the Air Force needed an all weather interceptor capable of Mach 2.  This was the 1954 ultimate interceptor, or the F-106.

But the F-106 was to incorporate more than just increased speed.  She was to be equipped with a very advanced avionics SAGE_computer_roomsystem, one tied into the brand-spanking new, and very complex Semi-Automatic Ground Environment (SAGE) computer-controlled air defense system that had just been developed by the Air Force.  SAGE, using the first mass produced computer (the AN/FSQ-7, which took up an entire floor of a huge concrete blockhouse, but was very, very advanced for its time and was the machine that gave the computer industry it’s start – it is the great grandfather of all modern computers), would be capable of guiding the F-106 interceptor virtually without any pilot input, from takeoff to touchdown.  It could perform automatic intercepts and greatly sped up the intercept process – critical if the USAF was to defend against transonic or even low-supersonic bombers.

But this automatic intercept capability required all manner of new avionics for the F-106.  These took time to develop, so that the F-106, originally desired to enter service in 1956, did not enter squadrons until mid-1959.  By that time, concern over air defense had lessened, as the big threat was now perceived to be the intercontinental ballistic missile.  Because of that decreased concern, and also due to its high cost, only 340 F-106s were built.

Proper area ruling on the F-106

Proper area ruling on the F-106

But these were prodigiously capable aircraft. Not only was the F-106 possessed of very advanced electronics and flight controls, she was a dream to fly, very nimble, and possessed of great thrust from her J75 engine.  In fact, she was USAF’s 777px-F-106A_102FIW_Tu95D_CapeCod_1982most capable supersonic dogfighter in the early 60s, and was much better in close in combat than the F-4 Phantom II, which Robert McNamara nevertheless foisted on the Air Force.  The F-106 had a top speed of Mach 2.35, had an internal weapons bay carrying four AIM-4 Falcon missiles and an unguided, nuclear AIR-2 Genie rocket.  The Genie was dangerous and unwieldy, and was rapidly phased out.  In its place, the F-106 got an M61 Vulcan 20mm cannon, giving the F-106 a good close-in combat capability.  Coupled with some other late improvements, such as a clear bubble canopy and some avionics updates, the F-106 could be a dangerous opponent in a dogfight well into the 1980s.

Firing a Genie

Firing a Genie

Even F-15s, if not well handled, could have problems with an F-106.

The F-106 was the last purpose-built interceptor acquired by USAF.  Various plans for replacements and upgraded versions were put forth, but the Vietnam War and then the post-Vietnam malaise insured none of those came to fruition.  Maybe next week, I’ll do a post on one of those proposed replacements, the F-12B Blackbird, a truly amazing aircraft.  Because it was never replaced, the F-106 wound up soldiering on in the USAF and Air National Guard until the late 80s, when it was finally replaced by F-16s.

The San Diego Air and Space Museum, located in Convair’s old home town, has a truly prodigious video library.  They have been slowly adding items to Youtube.  See below some videos on my second favorite aircraft of all time (after the glorious F8U Crusader):

The first video gives an overview of the F-102 and F-106 programs from the perspective of 1956:

The below shows the program to add the M61 Vulcan cannon to the F-106:

The following is a pretty arcane video that shows how the F-106’s very advanced (for it’s time) flight controls worked.  It illustrates how the pilot could use the electronic commands from the ground to intercept an enemy aircraft.  Some nice shots of the 106’s very advanced radar screen.  Too bad they did not show the 8″ movie map display down between the pilot’s legs, I’ve never seen video of that:



1. Blaine - January 11, 2014

Keep ‘me coming. This is a great series.

Incidentally, could you please pray for the crew of the MH-53E that went down off Virginia Beach this week? Great people died, one a long time friend and squadron-mare of mine. Very sad situation. Thanks.

tantamergo - January 13, 2014

I did not even know. I don’t follow such things very much anymore, especially since Lex passed away.

I am sorry for your loss. God bless you!

Blaine - January 13, 2014

Obviously that was supposed to say squadron-mate. I hate typing on a phone. Thanks for the prayers.

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