Document created: 2 June 04
Air University Review, November-December 1972

Low-Cost Remotely Piloted Vehicles

The potential for providing low-cost tactical remotely piloted vehicles (RPV’s) should be considered and emphasis given to the development of an unconstrained innovative approach in establishing their logistic and maintenance support systems. Choice of the appropriate logistic and maintenance characteristics can significantly influence the overall design of RPV’s and their support aerospace ground equipment (AGE). Critical examination of various design and support system options is in order, with the goal of initiating changes in the expensive methods currently used to obtain military hardware.

The RPV’s discussed here are primarily ground-launched, controlled from a ground station even when they are a long distance away (e.g., more than 100 miles), and returned for recovery and reuse; however, most of the ideas expressed are also applicable to other possible variants of RPV’s, such as expendable vehicles and those launched and controlled from aircraft (for example, Condor). Indeed, a low-cost philosophy should be adopted for all kinds of RPV’s.

Requirements for RPV’s should direct that low life-cycle costs be provided for these new tactical weapon systems as well as define the expected mission performance goals. The motivation to reduce costs—not only the initial investment costs but also those associated with operation, maintenance, and logistics—should dominate the actions taken by the research and development (R&D) community in response to operational requirements. Specifically, this means that a new maintenance and logistics approach should be taken for the support of RV’s; the kinds of systems now used to support military aircraft should not be envisioned as satisfying RPV requirements. We should insist on simplified support systems, those that can provide the lowest life-cycle costs. As on example, we should strive for RPV system concepts that will require a minimum number of skilled personnel, since manpower constraints on military systems may be much more severe in the future than in the past.

Costs of an unmanned flying vehicle can be reduced in many ways. A principal method is to establish practical yet minimal performance requirements for the vehicle’s maximum airspeed, payload, versatility, and the environmental conditions under which it must operate. Strike RPV’s will usually be flown below 20,000 feet; they should not be required to operate at 40,000 or 50,000 feet. We must keep in mind that RPV’s are not expected to survive a large number of sorties, since they will be used primarily—perhaps solely—in the most heavily defended environments. They will not be expected to fly more than 10 to 20 sorties. Many subsystems will be required to operate perfectly at all times; an occasional failure of an essential subsystem may cause a catastrophic loss. Therefore, higher operational losses can be expected for RPV’s than for manned aircraft losses caused by accidents other than losses related to hostilities. Since man-rated qualities do not have to be designed into the remotely piloted vehicles, and entirely different philosophy of design can be accepted than that applied to manned aircraft.

If we consider all RPV’s as expendable, those that can be recovered and flown again may be called “reusable expendables.” They may be categorized as nonaircraft class of military hardware—similar to a round of ordnance or other weapon—and an appropriate design philosophy followed. Because many RPV’s will be necessary to be effective in an important conflict, we should think in terms of automated fabrication and high production rates, like those of the automobile and ordnance industries.

Cost advantages could accrue from designing RPV’s in modular form, that is, from major components that can be easily and rapidly removed and replaced when necessary. Some components can be considered throwaway items; when they fail or are damaged, they can be replaced easily by either new components or usable ones from salvaged vehicles. Cannibalizing, though inappropriate for manned aircraft, could be acceptable in RPV maintenance procedures. The major components could be assembled at a staging area close to the launch site, having been withdrawn from storage and shipped by air or other means to the staging area. The assembling process must be simple, merely installation of bolts or screws and attachment of electrical connections, fuel lines, hydraulic lines, etc. The engine pod should be a single module that can be replaced without excessive time or skill. The necessary maintenance skills should be limited, perhaps to the use of torque wrenches and safety wiring. This will require much imagination and innovation in the design of RPV airframes. The potential of a modular concept cannot be ascertained without design and evaluation of low-cost components that allow only minimal repairs, if any.

Combat elements will need replacement RPV’s frequently during intense conflicts extending over weeks or months; the loss rate may be as high as 10 or 20 percent. Thus the modular approach looks attractive as a way to facilitate getting many replacement RPV components to the operating theater. Also, it may be highly appropriate to keep the physical size of the vehicle small. If a modular approach is introduced, the Air Force could conceivably get wings from one contractor, fuselages from another, and so on, with an effective system integration management organization. (Perhaps electronic companies can be the RPV prime contractors!) This modular approach may be vital if RPV’s are deployed to small airfields suitable only for small cargo aircraft or if they are transported by trucks to remote sites. Considerable transportation support may be needed, but the resources spent on logistics of this kind will be less costly than providing many skilled mechanics to repair and recondition a limited number of RPV’s. The transportation problem will exist to some degree regardless of the maintenance and design concepts adopted because of the expected RPV loss rate when they are used in combat.

The RPV components must have a long shelf life. An efficient packaging technique is needed, such as using plastic bags to protect the RPV components from salt spray, moisture, or other severe environment. Once an RPV is assembled, it is expected to be operational for only a short time, so the severe requirement for corrosion resistance need not apply.

Design of RPV avionics is another area in which large savings could be made. RPV’s will have many electronic components, comprising perhaps 30 to 50 percent of the total cost, so considerable attention must be given to making them inexpensively. While they must have some reliability, the reliability we should be thinking of is in terms of flying the vehicle 10 to 20 sorties rather than for thousands of hours. Where practical, the concept of throwaway electronic equipment should be encouraged, like that used for inexpensive transistor radios and integrated circuit designs. If an avionic unit does not check out, one black box should be replaced by another; resources should not be expended to repair bad ones. Again it is clear that requirements established by military specifications and standards should not be applied to RPV electronic components; and if commercial-quality elements are used, the price can be greatly reduced—by at least a factor of 10 and perhaps by a factor of 100. Costs may be substantially reduced if more optimum temperature and pressure environments are provided for electronic units in the design of RPV airframes. We could then expect satisfactory performance from many low-priced commercial-quality electronic components.

The RPV system should be designed to permit testing of various components before the vehicle is committed to the launch pad. Automatic go-no-go tests for the RPV electronic components should be possible using aerospace ground equipment rather than equipment in the RPV. Also, the engine could be checked by measuring the pressure ratio of the compressor at a given rpm. This may be accomplished without starting the engine by using an external power source to rotate it to the desired rpm. A simple check of the condition of bearings can be made by timing the period required to slow down between two rpm values.

Care must be taken, however, for the essential functions of the vehicle to have some degree of redundancy or an alternate way of operating without forcing costs too high or adding too much to the RPV’s size and weight. As an example, the autopilot should have a self-contained mode of operation; then if loss of radio contact occurs, the RPV could still fly to the starting point or other pre-programmed location.

Two major elements of RPV systems should not be compromised as far as quality is concerned. These are long-lifetime elements: the relay of aircraft and the control centers. The relay aircraft for most tactical combat scenarios using RPV’s must be able to support a number of RPV’s at the same time. It would be impractical in most cases to provide a drone relay for a single RPV, as a drone would reduce the reliability and increase the operating cost of the overall system. Therefore, a highly reliable manned aircraft should be used for the relay aircraft, committed to service a number of RPV’s. One relay station may be designed to handle concurrently three or four RPV’s at the target, transmitting television signals or other imagery, and, in addition, eight or ten others en route, sending data using a narrow bandwidth and time-multiplex techniques. Thus a dozen or more remotely piloted vehicles can be airborne at the same time under the control of a single control center and through one relay aircraft. While the electronics in this relay aircraft would probably be complex and expensive, it would be unwise to chance losing it for noncombat reasons. The relay aircraft probably will remain behind the forward edge of the battle area (FEBA) at a very high altitude to reduce its vulnerability and provide a long line-of-sight range without horizon cutoff so that RPV’s can be flown at distances of 200 to 250 nautical miles from the relay aircraft. A U-2 or an RB-57F may be appropriate, or, if more payload and volume are required, perhaps a C-141 or other jet cargo aircraft having a loiter altitude of at least 40,000 feet should be used. The relay aircraft may need to remain on station for long periods, as much as 8 or 10 hours; thus one aircraft could conceivably support a hundred RPV’s during the station period.

The other major element of the RPV system that needs special attention for efficient design is the ground control center. It should contain a general-purpose computer to provide versatility through appropriate software as changes occur in the control center functions or RPV designs. A number of control stations should be required within a center: three or four where the remote pilots control RPV’s by imagery from on-board sensors, and another stations with three or four people to monitor and control eight or ten other RPV’s going to and from targets. There may also be a station for launch and recovery of RPV’s. Therefore, a control center can be envisioned consisting of three or more trailers compatible with bare base or 407L equipment and transportable in a C-130 or other airlift aircraft.

The development and design of future RPV systems should not be skimped on with regard to cost or quality. Large overall savings can be made if sufficient R&D money is provided early in development and directed to finding ways to reduce costs and provide the basis for an appropriate logistics and maintenance system such as the one mentioned earlier. Experiments to realize throwaway components should be supported. Automated production techniques should be developed so that the Air Force will have the capability to mobilize quickly after a production run on an RPV design has been discontinued. We should experiment with different materials and fabrication techniques to reduce the labor costs in the construction of the vehicles. Various types of plastics and perhaps epoxy and paper structures may be acceptable and most economical in certain areas.

Different techniques should be tried for launching and recovering all unmanned vehicles. Programs should be initiated to develop and evaluate new techniques in order to incorporate the best launch and recovery capabilities for the future RPV designs. One way to save money on RPV operations is to reduce the requirement for support aircraft. The only aircraft needed in an RPV strike or strike support system is a relay aircraft. Ground launch and some type of ground recovery by a horizontal landing are predicted to be the least expensive and the most desirable methods, especially if many sorties are required of each vehicle in a short period of time. Unless unique requirements exist, tactical RPV’s should not be limited to launch from DC-130s and recovery by helicopters. The present techniques place excessively restrictive limitations on future RPV system designs. 

The opportunity exists to obtain viable new tactical weapon systems at very low life-cycle costs. All methods that can force the cost down should be investigated as compared to costs of present aircraft methods and procedures. RPV’s will have a short expected lifetime and will not require the reliability of man-rated systems. Therefore, today’s aerospace standards, specifications, and practices and Air Force aircraft management procedures do not necessarily apply to RPV’s. Large cost savings can be obtained if commercial-quality components and materials are used and automated production techniques are developed. This approach can lead to throwaway components, which in turn can revolutionize the maintenance and support required and effect a large reduction in life-cycle cost.

Santa Monica, California

Contributor

Lieutenant Colonel Robert H. Jacobson (M.S.M.E., University of Southern California) is assigned to Hq USAF with duty at the RAND Corporation, Santa Monica. He has flown jet fighter, U-2s, and, in Southeast Asia, F-4s. He served as instructor, Test Pilot School, Edwards AFB, and a tour as test pilot. At RAND he works on RPVs, Loran, conventional weapons, and other tactical areas. His next assignment is with Aeronautical Systems Divisions, AFSC.