PilotPhotog Podcast

X-31 Thrust Vectoring Technology Demonstrator

July 05, 2021 PilotPhotog Season 1 Episode 23
PilotPhotog Podcast
X-31 Thrust Vectoring Technology Demonstrator
Show Notes Transcript

Part of the NASA technology demonstrators, X-31 was designed to test thrust vectoring technology by using a delta wing, canards, and vectored thrust from the engine.   Designed and built by  Rockwell and Messerschmitt-Bölkow-Blohm or MBB, The X-31 was  part of a joint US and German project known as the Enhanced Fighter Maneuverability program or EFM.  The goal of the EFM was to use thrust vectoring and an advanced flight control system to provide enhanced control authority in pitch and yaw, this resulted in significantly more maneuverability than most conventional fighters.


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You're listening to the PilotPhotog Podcast. Let's listen to the story of the Enhanced Fighter Maneuverability demonstrator. The <inaudible> Part of the NASA technology demonstrators. The XRD one was designed to test thrust vectoring technology by using a Delta wing canards and vectored thrust from the engine Designed and built by Rockwell and Messerschmitt book and Blohm or MBB. The X 31 was part of a joint US and German project known as the Enhanced Fighter Maneuverability program or EFM. The goal of the EFM was to use thrust vectoring and an advanced flight control system to provide enhanced control authority in pitch and yaw. This resulted in significantly more maneuverability than most conventional fighters.


Hey, couple of interesting specifications for the <inaudible> its maximum speed was 782 knots or Mach 1.28 And the engine was one General electric F 4 0 4 GE 400 turbofan engine, which produce 71 kilonewtons of Thrust. It's also the same engine found and the F 18 super Hornet development. Although the X 31 Was basically an all new airframe design, it did borrow heavily both and design concept and actual parts from other aircraft. For example, the front section is from an FAA 18 Hornet, which includes a canopy cockpit and ejection Seat from the F 16, the landing gear rudder pedals, nose wheel tires, and fuel pump deleting edge flap drivers from the S 16 XL, the V 20 twos control surface actuators.


The main landing Gear wheels and brakes are from a Cessna citation for the canards the B one B lancers control vein spindles. And initially the emergency air start system from the F 20 Tiger shark. The use of other air worthy Parts was intentional. Has this significantly reduce development time. Additionally, Rockwell developed a flyaway tool and concept to produce The X 31. Flyaway tooling is a process by which the tooling is used to create. The assembly becomes part of the air frame so that when the aircraft is completed, it flies away with its own tooling. Aside from vector Thrust, the X 31 may use of a Delta wing paired with <inaudible>. This design concept have been using the sob <inaudible> and would also be seen in the sole profile, the Eurofighter typhoon and the sob grip and the XRD ones' Delta when he was actually a cranked arrow or double Delta wing, such as those seen and the S 16 XL and the sob DRock and before, and the computer control canards assist was stability and increased Maneuverability.


Thrust Vectoring is accomplished By using three paddles, which direct the engines exhaust as part of the EFM program. Two X 30 ones were built with the first one flying in October of 1990 Performance and testing The goal of the EFM Program was to give the next generation of highly maneuverable fighters, design information and concepts that could give them advantages and close combat. This was done by demonstrating maneuvers at high angles of attack and focusing an agile flight within the post-fall regime to understand what the post-sale is. We need to review the angle of attack Or AOA fixed wing aircraft Have what is known as a cord line, which is a reference line that is drawn through the wing, has an aircraft flies to the air we'll pitch up or down. And the vectors generated between the relative Bush of the aircraft and the atmosphere.


This form is an angle, which was you referred to this AOA and it was usually represented by the letter alpha every aircraft will stall when it reaches this critical angle of attack or AOA, which in most air foils is somewhere between 15 and 20 degrees for The X 31. That was actually 30 degrees. Thrust. Vectoring helps compensate for the loss of controls that occurs during a saw and allows the aircraft to fly beyond this normal critical area. The attack operating beyond the critical AOA is known as post hall. And this aspect of fly was extensively studied with the X 31 during its time, right? And flight side of the X 31 achieved several milestones in 1992, the X 31 demonstrated a 70 degree AOA in 1993.


The second next 31 demonstrated a post all minimum radius, 180 to return, which was not possible by conventional aircraft. This maneuver became known as a Herb's Maneuver. The maneuver is named After German scientists and MBB employee, Dr. Wolfgang Herbst, who was a proponent of utilizing post-sale maneuvers and air to air combat. The maneuvers also referred to as a J turn and is generally considered more useful and combat than the Cobra Maneuver. The <inaudible> also Flew tactical maneuvers against an F 18 and other tactical areas. Okay. And in November of 1993, the aircraft reached a speed of Mach 1.28 in 1994, your sophomore was installed on the X 31 to demonstrate the quasi tailless Operation.


This was made possible By the ability of Thrust Vectoring nozzles to provide adequate yacht and Pitch control. Overall 500 Test flights were flown between 1990 and 1995 between the two prototypes. However, the program was not without incident in 1995, after 292 test flights, the first X 31 prototype crashed just north of Edwards air force base. The result of the crash was caused by ice inside the pedo tube, which set an incorrect airspeed data to the flight control computers, leading to a departure from controlled Flight. There were several factors That led to this, including replacing the heated Pito tube with an unheated one, along with both the ground crews in pilot, being unaware of the developing problem and not resorting to an override option of the computer controlled system, by going to fix flight control gains.


Instead while the pilot ejected safely, this led NASA to produce a 2005 film and titled <inaudible> and breaking the chain, which focused on what went wrong and how to prevent future mishaps Legacy with over 500 Test flights carried out between the two X 31 prototypes the data which the EFM program gathered was instrumental in providing designers with a better understanding of aerodynamics, developing effective flight controls and fly control systems that incorporated Thrust Vectoring. Some of these findings would be applied to the F 22 and today the remaining XRD one is on display in an exam in Germany. You can say the X 31, along with the F 18 Harvey Wrote the book on Thrust factory. What do you think is the X 30 woman of the lesser known NASA X planes?


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