The Smart Mortar


This document is a discussion of what we feel is a new type of control and management software.  There are many possible areas where a control and management software could act. This new software that we are introducing is a software that manages and controls a real physical item and our name for this physical item is: “The Smart Mortar.”

Our objective in this discussion is to introduce and describe a new type of software. We feel introducing a new software is clearer if we describe this software as it controls and manages a specific item.  We feel it adds unnecessary confusion if we simultaneously discuss features of the software and features of various types of physical items that the software could manage. To prevent this type of confusion, we choose to include discussion of only one version of the Smart Mortar. We will describe this Smart Mortar by simply stipulating its features. We recognize that other versions of a “Smart Mortar” are probably possible, but we choose to limit this discussion to only one spedific Smart Mortar.

We plan to demonstrate how this new software functions by a format where we apply this new software to the Smart Mortar. We will add discussion that shows why particular features of the Smart Mortar were chosen, but we will not devote much discussion to justifying or advocating the features of the Smart Mortar, instead we will just state: here is the Smart Mortar, here is its overall purpose, here is how it is deployed, and here is how it behaves.

The Smart Mortar is a type of flying device. When the Smart Mortar is functioning in its normal mode will not travel in purely ballistic flight.  Since its normal flight is not ballistic, we will refer to the Smart Mortar as a Drone.

The Drone is a military item and its purpose is summarized below:

 1) It will act as a flying device to carry an explosive device from a ground location (launch site) controlled by Friendly Forces to a ground location (target) controlled by Enemy Forces,

 2) It will use on-board software and physical structures to implement as-needed flight control during its flying time so that it will fly to its target site using controlled flight.

3) It will use controlled flight actions at an appropriate moment to cause itself to fly downward so that it will fly to and detonate its explosive charge at the ground location of the target.

The Flight Event is the entire extent of the time that the Drone is in the air. This Flight Event is divided into three phases. The first phase is named the Ascent Phase, the next phase is the Gliding Phase, and the final phase is the Impact phase.  The Ascent Phase begins by transfer of an energy impulse to the Drone. This energy transfer causes a rapid increase in the Drone’s airspeed. The initial motion of the Drone will be constrained so that it leaves the ground travelling upward at a very steep angle with an initial airspeed will be 700 mph. As it travels upward, it will exchange airspeed for altitude. At about 30 seconds into the ascent, the Drone will be at an altitude of about 14,000 feet with an airspeed of about 45 mph. The on-board software controlling the Drone will cause its flight control surfaces to bring the Drone into a transition maneuver.  This transition maneuver will decrease airspeed but will also bring the Drone into a glide (nose down but almost horizontal flying). At this point, the Drone begins the Gliding Phase of its Flight Event. During the gliding phase, the Drone will exchange altitude to maintain its airspeed at about 40 mph. Its glide angle in still air will be about 20 degrees, and its speed over the ground will be near to 40 mph. It is desired that the Drone will impact the target area with the Drone flying essentially straight down with a large airspeed. This desire requires that the Drone will need to transition out of gliding flight which it will achieve by a nose down flight control action. This nose down event transitions the Drone from the Glide Phase to the Impact Phase. At the end of the Impact Phase, the Drone will impact the ground level with a significant vertical velocity. The Drone’s on-board explosive device will have a “trigger” mechanism, so that, if there is onset of rapid deceleration, this trigger will initiate detonation of the Drone’s explosive device.

The event that gives the Drone its initial airspeed is an impulse given to the Drone by placing air at very high pressure at the back end of the Drone. As this air pressure pushes on the back of the Drone, it will accelerate the Drone forward rapidly increasing the airspeed of the Drone from zero to 700 mph. Control of this air impulse will be that the Drone is placed in the breech of a pneumatic cannon. This cannon is 8 feet long, and the air under pressure is introduced to the cannon behind the Drone by a rapid action valve. The effect is that the Drone will be pushed through the cannon barrel. At the end of the 8 feet of travel in the cannon barrel, the Drone will now have an airspeed of 700 mph, and since the cannon barrel is pointed upwards at about an 84 degree angle off of horizontal, then the Drone will leave the cannon barrel flying essentially straight up with an initial flight airspeed of 700 mph.

After the launch event, there are no propulsive energy sources available to the Drone, other than the force of gravity. The control software in the Drone can increase the Drone’s airspeed by requesting the flight control surfaces of the Drone to cause an increase in its nose down attitude.  If the Drone is in a nose down flight profile, the gravity force will cause an increase in negative vertical velocity. (We define vertical velocity as being only the portion of the airspeed along the vertical axis of motion. We define negative vertical velocity as being vertical velocity toward the ground).  The flight control software also has an ability to request the flight control surfaces to cause a nose up action. Nosing up will cause the Drone to exchange negative vertical airspeed into positive horizontal airspeed. By using these nose attitude alteration events, the flight control software can use gravity forces to modulate both the vertical and the horizontal components of the Drone’s flight.

The Drone will not have an independent ability to initially designate a location on the land as a target. Initial specification of what location is a target will be done by military forces.

The manner of action of this Drone as it progresses towards a successful conclusion to its mission requires that multiple processes must occur concurrently. We will describe in more detail the steps of the Drone’s behaviors as it progresses through its mission so that one can understand why this control software is constructed to allow multiple loops of software activity to be all occurring concurrently.

The Drone’s on-board software will have an ability to calculate where above the ground is the Drone’s location as compared to where is the designated location of the target.  This software will repetitively calculate what is the Drone’s predicted impact location. The software of the Drone will also send commands to the control surfaces of the Drone to alter the flying characteristics of the Drone to try to keep the Drone’s predicted impact location to be congruent with the target’s location.

Another way to describe this is that the software of the Drone in a repetitive loop fashion will:

  1. Establish where does the Drone’s flight control software consider the Drone to be with respect to the land beneath the Drone?
  2. Stipulating that the Drone control software prefers the Drone to fly about 3000 feet essentially straight down immediately prior to ground impact and detonation, where is the best place in the flight path to place the transition point for the Drone to convert from the Gliding phase to the Impact phase?
  3. Using extrapolation of the current flight path, and remembering 2) above, does the current flight path generate a predicted impact point that is congruent with the desired impact point?
  4. Do the on-going calculations of the software, considering 2) and 3) above, demonstrate control surface changes that should alter the Drone’s flight path to increase congruence between the predicted and the desired impact point?
  5. After review of the Drone’s current sensor data, are there any modulation or moderation restrictions that should be placed on the suggested flight control changes calculated from 4)?
  6. After factoring in considerations from 2), 3), 4), and 5) above, the flight control software releases commands to implement flight control surface changes and then b), (in a loop fashion) the software brings itself back to 1) above and starts this control sequence again.

The Drone’s Gliding Phase is chosen to be high altitude, low airspeed. These parameters are chosen for several reasons.

The Drone’s altitude represents an energy storage device since the Drone can lose altitude to acquire propulsive energy.  The Drone cannot maintain its airspeed unless it expends enough energy to overcome the drag effect of its airspeed.  Altitude is the only source of propulsive energy available to the Drone. This means that, for the Drone to maintain an airspeed, it must give up altitude to acquire the energy needed to overcome the drag of that airspeed. Since higher airspeed generates higher drag forces, then energy balance issues require that the Drone must lose altitude more rapidly if it chooses to maintain itself at a higher airspeed.

We prefer the Drone to spend its Gliding time at high altitude. Our basis for this preference follows:

  1. Higher Gliding altitude decreases the probability that the enemy will detect the Drone, which lowers the probability of defensive action against the Drone by the enemy. 
  2. Higher Gliding altitude increases the survivability of the Drone against defensive weapons fire, if the Drone is detected, because it is harder to successfully strike targets at high altitude.
  3. Higher Gliding altitude allows transition to Impact phase at higher altitude which allows higher negative vertical velocity (higher airspeed) for the Drone when it is near to the target.
  4. Higher airspeed during this final (near to the target) portion of the descent decreases the probability that enemy forces will detect the descending Drone.
  5. Higher airspeed during this portion of the descent also means that, if the enemy does detect the Drone, it is more difficult to manage defensive fire so that is successfully strikes the Drone.

We prefer the Drone to spend its Gliding time at low airspeed. Our basis for this preference follows:

  1. A slow airspeed during the Gliding Phase means that the Drone’s on-board control software will have more time to analyze navigation issues and calculate solutions, particularly the continuous upgrading of: a) where is the Drone? and b) can the Drone continue to image the target?
  2. A slow airspeed gives the control software more time to evaluate the Drone’s flight path and flight stability, and more time to calculate and implement flight control solutions.
  3. A slow airspeed decreases the ability of air flowing past the Drone to either start or worsen damage to the physical structure of the Drone.  Progression of damage to the physical structure of the Drone probably will degrade performance parameters.  Also, progression of physical damage to the Drone will eventually cause loss of ability to maintain controlled flight.

The Drone will be destroyed at the end of its mission. Consideration of this outcome makes it reasonable to design the Drone so that it is not unnecessarily complex or expensive.  The Drone is a military device and if it has a non-successful mission, the results from this non-success would be impact (and explosion) at a location other than the target. Explosion not at the target can result in undesired results, some of which may be severe such as collateral injuries and/or collateral structural damages.  Consideration of these outcomes make it reasonable to increase the cost and complexity of the Drone to make successful completion of the mission highly probable.  Balancing these considerations implies that high reliability of control and mission completion should be designed into the Drone, but that, otherwise, increased cost and complexity are not wanted.

Keeping the considerations above in mind, we can list some design principles that gave us the Drone design we are using.  We wanted to minimize parts of the Drone that are moving parts. We understand that the entire Drone is a moving part because it is flying along. By use of the phrase “moving part,” we mean parts of the Drone that move with respect to the Drone, or parts of the Drone where these parts have sub-parts, and these sub-parts move with respect to the overall part or with respect to the Drone. 

We wanted to limit the abilities of the sensory items of the Drone, as follows:

  1. Considering Navigation, we only need sensory data that allow calculations to establish and repetitively update a) where is the Drone? and b) where is the target?
  2. Considering Flight Control Aeronautics, we only need sensory the data that allow maintenance of controlled flight for those flight configurations that the Drone most likely would encounter
  3. Considering Flight Control Piloting, we only need sensory data that allow control of the flight path in a manner that is stable, controlled, and directs the Drone to the target.