THE ARBALEST:
THE ARBALEST: IRREGULAR WARFARE AIRCRAFT
Shown armed following illustrations with six Hellfire AGM-114, Front Turret: Stabilized “precision fire system" using a 50 cal weapon (12.7mm), Main Turret armed with a M230 Chain Gun (30mm).
The DoD has been looking for Aircraft for Irregular Warfare of late: “U.S. Needs Stealthy Airlifter” (link), and ast year the DoD was also been looking for a “COIN / CAS aircraft” (link). There is a clear gap in the market between traditional fighter, support planes designed for maneuver warfare, and the emerging tech around irregular warfare. One might call the new platform an armed “bush plane”. It is an interesting question: it is in some way to define a general class of aircraft that sits between helicopters and typical aircraft. This is a study that makes an attempt to take a fresh look at this paradigms. Updated: August, 22th, 2010
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“The Arbalest”: A Light Attack Armed Reconnaissance (LAAR) Aircraft.
Low cost COIN / LAAR Aircraft are being bought by many Nations. Typical of these aircraft is the Embraer EMB 314. This is a beautiful plane designed in Brazil. Without casting aspersions these aircraft, they function within a similar design paradigm as a P51 Mustang. In fact in many cases they resemble the Mustang. These aircraft are multi-role fighters pressed into the role of Combat Air Support (CAS).
The Arbalest concept has “Very Short Takeoff and Landing” (VSTOL), it can tote a lot of fire power, or hang in the air for hours. The Arbalest sits between a A10 Thunderbolt II (aka. The Warthog), an AH-64 Apache and a MQ-9 Reaper UAV. (Everything is “off the shelf” or under development, except the airframe.) This concept attempts to represent clear thinking about set of problems represented by the DoD’s LAAR solicitation, “A Clear Design Brief” if you like.
Is the reuse of a P51 Mustang is really the best solution for contemporary COIN / CAS / LAAR platforms? The Arbalest CAS/COIN Aircraft - M230 Chain Gun (30mm)
The Arbalest : Takes its name from the steel crossbow that resembles the form the the airframe when bent. The steel crossbow was a contributor to the end of the age of Armor. It allowed untrained archers hiding behind walls to effectively pierce the armor of mounted knights. It was an inexpensive solution to a long standing problem.
The Arbalest is a single engine, light combat aircraft is designed for patrols, fire support, e-warfare and observation. Any such aircraft should be field deploy-able and have STOL capabilities. It should fall between an Apache, an A10 and a Reaper in capacities. Yet it should cost much less.
What is needed is a tight design brief for a contemporary CAS / COIN / Observation platform: An idea started to form that this plane would be stationed directly with forward units, (like a helicopter) providing trusted and immediate air support. However, the long loiter time and ability to fly at altitude provides real gains for Combat Air Support.
- Fuel Efficient
- Inexpensive
- Survivable: Armor for Crew and Engines
- Easy to Fly – or Learn to Fly
- Low Stall Speed
- Long loiter time
- E-Warfare / Observation / Survey
- All Weather – Night Vision
- Known Technologies
- Precise Firepower
- Suitable for forward deployment
- VSTOL (Very Short Take Off and Landing)
- Rough Runways
The Arbalest - Key Features
This resulted in a design using a “Box Wing” and “Ducted Fan” propulsion: The “box wing” allows the use of narrow wing cross section creating lower drag and greater wing area in a smaller footprint. The “Ducted Fan” creates more thrust than a conventional propeller and quiets the noise of the prop. Further the ducts allow the thrust to be “Vectored” to create additional lift. Combined with the low stall speed and tight turning radius (due to many vertical surfaces and short wing span) this plane can loiter over head and provide precise fire support to troops on the ground.
The Arbalest can be stationed close to combat areas and take off quickly on improvised run ways due to its large wing area and ducted propellers. Further, the box wing creates a form that is self bracing allowing a stronger air frame than conventional designs. The design shown here is intentioned as “overbuilt” to withstand decades of deployment. (Note the “fat ass” and chunky construction in the illustration “Project Characteristics” .) The Arbalest Landing - Short Takeoff and Landing (vSTOL) - (Time to redraw the landing gear.)
This airframe can function in multiple roles. With a similar wing area as a Reaper it could fly high and observe the goings on of the world. However, the low stall speed allows it to support ground troops and fly Nap of the Earth. “Slow and Low” if you like. The Arbalest’s draw back is that it will never be as fast as an open prop plane or jet. This platform will never be a great air-to-air fighter. It is designed for permissive environments. The Arbalest CAS/COIN Aircraft - Front View
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Very Short Take-Off and Landing (VSTOL): Utah State University’s Space Dynamics Laboratory lightweight, stabilized turret
The Arbalest is designed to be Very Short Take Off and Landing (vSTOL). The ducted props should “sit” near the center of lift/gravity. That is to say between the wings so they can “vector with thrust” and increase lift. The wings needs some forward speed to provide the lift and come into play, that means VTOL will not work here. Not making it Vertical Take Off and Landing (VTOL) was a design compromise.
Armaments:
This platform is designed to provide precise fire support to ground troops. The “Main Turret” allows it to engage enemy forces with more precise fire than conventional wing mounted arms. To further the increase the accuracy of the platform the “Front Turret” has two gyro stabilized mounts that allow marksmenship like percision at range. A system such as Sagetech’s TAPSS system could be used. With a range of 1500m this allows single individuals to be targeted with much lower risk of collateral damage. There is an emphasis on firearms rather than guided munitions with a view toward operational cost. Bullets are simply less expensive than missiles . That said with the heavy Arbalest is capable of carrying a full complement of guided or unguided munitions mounted on it’s five hard-points.The
Cargo Area: This is a recent change due to a suggestion. A small cargo area has been placed in the back of the plane. This will be about 3.5m3 (125 cu ft.). It is large enough for a stretcher and attendant, Various packages would be possible: a radio operator / eWarefare Officer / life raft or supplies. It will be accessed by a back hatch of 1000mm x 1500mm (watch your head). This is still being worked into the design and is not reflected in the illustration here.
In the course of this project I came across a NASA Student Competition winner from 2002 “the Ikelos”. (Link) This was encouraging as the design was quite similar: In fact I shortened the ducts after the project below. (Their wing design is much better than mine.)
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NASA Concept 2002
NASA and the FAA honored students from seven universities today as winners of the 2002 University Student Competition
TECHNOLOGY INNOVATIONS CATEGORY — SECOND PLACE (Link) Design: Ikelos By: Virginia Polytechnic Institute & State University, Loughborough University (UK) Description: A team from Virginia Polytechnic Institute & State University and Loughborough University, United Kingdom took second place. Their joint effort resulted in “Ikelos,” an aircraft featuring a box-wing design with fans powered by a rotary diesel engine. This uniquely designed aircraft allows pilots to take super-short takeoffs and landings.
The team’s design – the ‘Ikelos’ aircraft – is capable of carrying two people and uses a box-wing configuration, with powerful flaps to allow take-off and landing within 150ft. A Rand-Cam rotary engine is mounted transversely to drive twin ducted fans, which allow for a dramatic reduction in noise compared to current light aircraft. The aircraft is predicted to have a range of 575 miles and to fly at speeds up to 160mph.
If it is possible to land the Arbalest in 50m, (150ft) then it would be possible land on the deck of a Destroyer. That short seems unlikely as the Arbalest is heavier than the Ikelos. However, with a bit of assistance it might be possible. It would certainly be suitable for Helicopter Carriers, Amphibious Assault Ship, or Queen Elizabeth class aircraft carrier. The VSTOL capacity of the Arbalest could be very useful in a Navel role. Combined with Harrier or F-35B STOVL, for air support / protection, the Arbalest could provide new fire power and endurance in naval roles. The Navy likes twin engine aircraft. Yet another design revision? I am going to guess that might take a bit more effort.
Project Under Development: Below is a sketch of a larger version of the Arbalest Concept. This came out of comments and reflections on the original entry. It is a slightly larger design to accommodate broad range of rolls. Including Naval roles and SOC Transport. This could be built in tandem or box wing design: the Box Wing is retained here for self reinforcing structure and antenna area.
Stealth Transport: Multi-role Aircraft
- Twin turboshaft design (GE T700 – common to both the Black Hawk and the Apache )
- Vector-able Ducted Prop (a compromise between efficiency and “stealthiness”)
- 2-3 Crew and 10-12 Passengers
- Retains similar armament as original design
- Low Observation Design
- Tail Obscures IR signature of engines
- Rear Loading Door
- Small size aids reduced radar cross section
Given the limited funds in defense budgets around the world it might be of interest to create a platform that functioned at an “80% roll” of functionality of Ground Support / Light Transport. Combined with the move toward modules the airframe could be reconfigured to fill various rolls.
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Thanks: This is a project that got “knocked out” in a weekend. Special thanks to Sketchup (Google Warehouse) and Wikipedia: Without these resources this project would have taken much longer.
Links:
Excellent Discussion of COIN/LAAR Aircraft by James “JJ” Jinnette, Colonel, USAF, ACCE Afghanistan Deputy Director (link)
DISCLAIMER: I am not an Aircraft Engineer, I am an Architect: If you happen to be an Aircraft Engineer or Aerospace company I would be interested in discussing the furthering of this proposal.
Change Log:
2014 - 04 - 08: Reposted to on-e.net
2010 – 08 – 24: Revised Range and Speed Calculated via Raymers Simplified Forumulas
2010 – 04 – 12: New Illustration “Key Features” and Cargo. Thanks to Philip West
2010 – 04 – 23: Link to Sagetech TAPSS System and various weapon systems.
2010 – 04 – 27: Intro Text and Sketch of “Stealth Transport”
March 27, 2010 | Filed under TECH and tagged with a10 thunderbolt, Afghanistan Airforce, close air support, COIN Aircraft, Combat Air Support (CAS), design paradigm, Irregular Warfare (IW), Light Attack Armed Reconnaissance (LAAR) Aircraft, Stealth Transport.
Tags: a10 thunderbolt, Afghanistan Airforce, close air support, COIN Aircraft, Combat Air Support (CAS), design paradigm, Irregular Warfare (IW), Light Attack Armed Reconnaissance (LAAR) Aircraft,Stealth Transport
