Although long or medium endurance and higher altitude cruising unmanned aerial vehicles (UAVs) are not high performance in the sense of an F-22 or SU-30, they are in fact extremely high performance when it comes to maximizing their design’s potential for the unique mission sets they were built to address. Usually this comes in the form of fuel efficiency, altitude, and survivability. With this in mind, the crash of the Global Hawk in the video posted above is incredibly relevant to the RQ-170 story for multiple reasons.

First off, flying at higher altitudes for long periods of time requires an aircraft design that utilizes a high lift yet very efficient wing design. The only problem is that as these aircraft fly higher their speed and maneuvering envelope becomes smaller. As altitude increases even small changes in speed, G force or angle of attack can cause the aircraft to stall and even enter a flat spin. This phenomenon is known in the aviation world as “coffin corner.” So, otherwise small flight control or command anomalies can end up putting the aircraft in a totally unrecoverable state.

So beyond the speculation of advanced Russian jamming equipment and cutting edge cyber attacks, lets look toward a simpler explanation for the drone’s demise in relation to the video posted above. If the RQ-170 Sentinel had a software or communications glitch that caused it to climb when it was already operating towards the top it’s operating ceiling, or to pitch up or roll abruptly, or the engine suddenly quit, the aircraft could have most likely departed controlled flight and return directly to terra firma. No cyber espionage or hidden agendas, just a plain old simple malfunction paired with an unforgiving performance envelope. Could this have been caused by a spoofed enemy command? Who knows, but in this piece lets concentrate on the physics of the situation, not the speculative causality.

Also what this video shows is just how an aircraft such as a RQ-4 or RQ-170, one made of composite materials and designed with a tremendous amount of lift, can literally flutter like a leaf back down to earth once they depart from controlled flight. I have spent some time close up and personal with the Global Hawk series of aircraft and I can tell you they are much, much more fragile in appearance than the stout RQ-170 drone. They are literally made of plastic, their wings flex like a piece of damp pasta and their radomes and components are toy like. Especially the smaller, earlier block version as shown in this clip. As you can see it hits the ground with a thud and surely some of its parts crack or are separated from the airframe, but there is no smoking hole, no massive fireball, no football sized debris field, and almost all of its internal components are surely intact. The RQ-170 put on display in Iran does have significant damage, the leading edge is banged up and punctured, the wings have been harshly split at their natural seams (see previous post for more details on this) and it would seem that the underside of the drone was badly damaged enough that it was not allowed to be shown to the public. Further, the Sentinel in question may have gone down in a slightly different manner than the Global Hawk in this video, where it hit flat but with some forward motion, allowing its wings and underbelly to take the brunt of the hit and then subsequently sliding to a full stop.

I hope this post helps to illuminate just how utterly wrong the quick conclusions that many “military aviation experts” had jumped to after hearing the news that the aircraft was possibly intact. Many could just not believe that there was not a huge debris field, or a smoking hole in the ground after the drone “plummeted from 50,000+ feet.” These are uninformed conclusions and most likely totally misleading under the circumstances. The RQ-170 could have made it back to earth with minimal damage to its upper side, and this video clearly showcases this fact.

A big thanks for a flickr contact of mine sending this over for review!

To access to all RQ-170 “Sentinel Down” related posts, in order from newest to oldest, please click on the link below!

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  1. b says:

    The RQ-4 is NOT a flying wing. Flying wings are inherently unstable and would not just spiral down 50,000 feet.

    • says:

      That is a very general statement moon, yes I understand they lack the directional stability of a tailed and straight wing configured machine but they can and have flat (or falling leaf) spun after departure from flight. Maybe not as cleanly as the global hawk but its physics at work. Also, the flight control system would surely do what it could to fight the spin to the best of its ability. Modern FBW systems can do some amazing things, and this may have allowed it to stay out of a totally uncontrolled spin where the attitude changes rapidly.

      Thanks so much for sharing your input, I love people with opinions!


  2. Rob says:

    So you’re saying it’s the 17/18/19th of the 9th moonth of the persian calendar, and therefore it’s completely unlikely that they set their camera to the 17/18/19th day of the 9th month of a julian calendar because it’s english translation is september not aznar? It’s that much of a stretch that they’d want photos at least semi-correctly tagged even if the 1390 is omitted? Perhaps the 2011 has something to do with 1390 being impossible to input into a modern camera?

    • says:

      I am not from that area of the world but I checked it on a converter and have maybe a half dozen emails explaining it to me in a positive light. Its an very unique coincidence that I cannot look away from, then the camera could have been just set wrong, mine is right now too.

      Thanks so much for posting here rob!

  3. AR says:

    Another point, the Global Hawk tested ejected all its fuel before impact.
    This should have decreased its weight very much and avoided any explosion or fire before impact.
    Furthermore the operator certainly tried to gain back control till the last moments. A Sentinel out of control, spinning after stall would certainly not eject the fuel, at least not completely. All steering commands used to rescue the UAV would change at some point to steering commands which would guarantee the destruction of it by avoiding a high drag, low velocity descent. After all this is a mission inside a hostile country and the technology inside the sentinel is very sensitive.

    I’m sure that this is a big difference compared to the test conditions of the Global Hawk. If there is no self destruct mechanism then at least maneuvering regimes which would guarantee a high velocity small area impact.

    However good find of course.

    • says:

      I cannot agree with this, we don’t know what the exact protocalls are for the RQ-170 in any circumstands OR if the system was even capable of executing those protocalls at the time. Many thought there would be a self destruct mechanism but that proved totally wrong as A. It is still intact B. Many sources have said it does not have one.

  4. Bart says:

    Don’t know if I’m the first to mention this… but the floors of the gym the RC was displayed in were WET? Could this baby have gone in wetlands or shallow water.. and still leaking water during “media viewing”?

  5. J says:

    Somebody should translate this:

    Interview is with Hossein Salaami, Deputy CinC of IRGC. He describes the various navigation, control, and communication systems of the RQ-170. He says it’s impossible for all the nav systems to have failed at once and then he has this sentence: “This bird came under the control of a secondary system [ours] and how this happened is a mystery that the Americans and others should think about”.


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