Been a while, here's a quick one. One of my all time favorite weird airplanes. Tacit Blue!
This plane just screams weird. Weird shape. Weird cockpit. Weird tail. Weird wing. Weird name. It looks like something an alien species would bring to earth, greeted by Will Smith in an F/A-18 screaming "WELCOME TO EARF!"
So, you may ask, 'Jake, what the hell am I looking at?' To answer that, lets first consider the time this aircraft was built. In the late 70's and early 80's, some brilliant minds at Lockheed were working on stealth technology. Stealth was all the rage. Lockheed came up with a method using flat panels to design the first truly stealth aircraft, Have Blue - A prototype that would eventually become the F-117A Nighthawk (I'll do one of these on Have Blue sometime). This technology was truly revolutionary. One story in Ben Rich's book Skunk Works recalls that the radar cross section of Have Blue was so small they had to clean bird crap off the radar model so as not to skew the results.
The principles that allow the Nighthawk to be stealth can be applied similarly to a curved surface, called a Gaussian surface. This is the direction that Northrop took with their stealth projects, most notably in the B-2, which you may notice has some similarities to ol' Tacit Blue here.
So Tacit Blue was a prototype for the B-2, right? Not exactly...
The air force wanted to deploy radar to the front lines on an aircraft with a low probability of intercept. Basically, they wanted to get a plane with a radar to the front lines and have it come home safely, very difficult to do in an era of smart weapons such as radar locking missiles. Naturally, a stealth aircraft would be a good way to do this. So Tacit Blue was born, partly to prove the Gaussian surface methods for stealth, but really to test the idea of deploying radar to the front lines on board a stealth airplane.
There's a lot of interesting things going on with this plane. First and foremost, the shape of the fuselage is very strange as a result of using the Gaussian surface for minimal radar cross section. This was really the heart of the program, and it succeeded in that respect, proving that this type of stealth technology works - Tacit Blue was reported to have a radar cross section of a bat! For reference, Tacit Blue is 55 feet long and about 48 feet in wingspan...so it's not that small!
The powerplant is also interesting. Two turbofan engines sit IN the fuselage, with air feeding in from the inlet on the top of the aircraft. They are exhausted between two V-tails. Why this configuration? Well, in my opinion this was a brilliant application of stealth. First of all, engine inlets typically get warm, both from the engines themselves and aerodynamic heating. By placing it on top of the plane, a heat sensing missile launched from the ground won't see the heat on the inlet surface. Burying the engines in the fuselage helps to mask their heat as well as their noise. And exhausting between the two vertical fins also helps to reduce heat signature and noise, much like the H-Tail on the A-10 Warthog II does. This is another place that the B-2 draws from the Tacit Blue - each inlet on the B-2 actually feeds two turbofan engines that are buried in the wing.
So what became of Tacit Blue? The air force decided that they could accomplish the radar mission from a larger aircraft further away from the front lines, this became the E-8 Joint STARS modified 707. Tacit Blue flew 250 hours over 3 years before being retired to a hangar in 1985. The B-2 Bomber flew 4 years later, in 1989, drawing a fair deal of its stealth technology from Tacit Blue.
You can see Tacit Blue now at the USAF Museum at Wright Patterson Air Force Base.