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Shrike Airsoft Bow


The Shrike Airsoft Bow photographed for the release of the first production run. Manufactured in the Dyson workshop at Imperial College London
The Shrike Airsoft Bow photographed for the release of the first production run. Manufactured in the Dyson workshop at Imperial College London

The Shrike has been an ongoing project of mine for the last 10 years. It's undergone 12 prototype stages, a pre-production run and a full production run before being approached by a major brand to license the design. The Shrike has been delivered to dozens of airsoft players around the world, in the UK, Europe and even the US and Asia.


The concept started as a relatively simple one. An evening spent watching a Youtube video where someone used the piston rods from the boot of a hatchback car and a spring from the underside of a sofa to create a rudimentary bolt-action sniper for airsoft was the moment of inspiration. The basic principle to which all airsoft replicas use to function, is some mechanism to compress air, and that air being used to propel a BB towards a target. Abstracting the idea of a spring and piston, the mechanism of a bow and arrow is remarkably similar, although the bow is perhaps more of a lateral / rotational spring than the linear ones used in spring action or AEG replicas. Arrows don't make great pistons with a field point, or broadhead, but changing that out for something cylindrical with an O-ring, and encasing the stroke length in a cylinder mounted to the riser gets the job done. This was pretty much it for the first prototype. The head of a Pritt stick attached to the end of an arrow, encased in some 32mm PVC pipe, bolted to the riser of the bow, and some garden hose looped from the end of the cylinder back to some 6mm ID aluminium tubing attached to the cylinder with jubilee clips, crudely sprayed matt black with some pound store paint (that I swear I can still smell to this day) and it was done. Each BB had to be barrel loaded, before drawing the arrow back and aiming. It wasn't fast, it wasn't mobile, but it was quiet, very quiet.


The first prototype of the Shrike, produced in 2015
The first prototype of the Shrike, produced in 2015

I was fortunate enough that my local site owner, who's known me since I was barely old enough to sign on to game days, upon thorough inspection, demonstration and chronograph testing (about 270 with a 0.2 at the time) permitted me to use the first prototype at a small summertime night game. With around 25 players across 50 acres, there was plenty of scope for sneaking around in the dark, letting off silent shots at reasonably close range with players having no idea where they'd been hit from, it was a perfect testing ground for the concept.



Over the next year or so, iterations improved, adding a hopper mechanism, largely through trial and error that could feed a single pellet at a time, improving velocity and reliability. The main mounts to the riser incorporated a hand tightened M10 bolt and a garden gate hinger that allowed for the airsoft attachment to be folded in line with the limbs of the bow, and slung over the shoulder, keeping hands free. Eventually in October 2016 the project was taken out in the light of day, used during a busy Sunday game at Warminster Airsoft. The Mk4 iteration had a 50 round hopper, applied a fixed hop-up to the pellets, and had a projectile velocity of around 450 fps, classing it as a bolt action with a 30 meter minimum engagement distance. Photos from the game day quickly began to circulate the airsoft community, and for the next few weeks I was inundated with messages about the bow from excited individuals who wanted to purchase one, or be involved in the project.


The Mk4 prototype in use at Warminster Airsoft in 2016
The Mk4 prototype in use at Warminster Airsoft in 2016

I quickly realised however that I was not a good enough archer to consistently be making these sorts of shots at 30+ meters. The combination of a 34lb draw weight, and 32mm bore cylinder was overkill, a challenge to use for a day, and not necessary for someone without enough practice to instinctively shoot arrows at that sort of range.

Future versions first reduced the cylinder bore down to 22mm, and then dropped to a 20lb draw weight youth bow, which when tuned brought velocity down to about 320 fps with a 0.2g, ideal for this platform.


Another year or two went by, with the Mk5 version dropping the cylinder size, and replaced some of the air hose connections with more robust, copper elbows. The Mk6 did away with the large, wooden recurve in exchange for a more affordable, more resilient and lower draw weight polymer youth bow, while adding adjustability to the hop-up system. This was one of the consistent challenges facing the whole project, to create a hopper based feeding system, capable of applying high quality and consistent hop-up performance - backspin on the pellets as they are forced down the barrel, for those unfamiliar with airsoft technicalities - this in turn creates a positive lift as pellets fly towards the target, effectively increasing accurate range and countering the pull of gravity that would otherwise cause the pellet to drop far sooner after leaving the barrel. Most hop units use reciprocating mechanical nozzles to load a single pellet into a chamber, and then allow pressurised air through to accelerate the pellet, while preventing a second or third round following down the barrel. The Shrike uses a complex set of geometries and fluid mechanics to provide sufficient vacuum and then back pressure to ensure only a single pellet is dropped into the chamber and forced outwards. The adjustability within the hop system allows for a potential loss of pressure in this system, as does having a reloadable hopper, so these had to be designed very carefully and with great precision to maintain this balance of pressures. The Mk7 expanded on this to allow the barrel to be replaced and the hop-rubber to be easily maintained.


By this point, the functional aspects were fairly well dialled in. It was a consistent shot, and offered reliable performance in any game conditions, visiting sites over the UK and taking plenty of knocks while consistently allowing me to eliminate other players in my now refined sneaky play style.


The Mark 7 prototype pictured at Spec Ops the Rock in 2017
The Mark 7 prototype pictured at Spec Ops the Rock in 2017

In 2017 I secured UK Design Rights for this project with the Intellectual Property Office, for the overall design of an airsoft bow, the pneumatic attachment for a bow that allows propellant of pellets, and the hopper based hop-up system that is the keystone to the function of the design. In 2017 this was also submitted as the basis for an additional Extended Project Qualification, where I elaborated in great detail the design process and technological influence that has lead to the creation of the Shrike.


Iterations from this point onwards were more about commercialisation that design proficiency. Increased emphasis was placed on robust components, increasing the strength

of known points of failure by reinforcing, using higher strength materials and minimising joints where possible. Standardised components were used where available, assembly and disassembly became easier and more consistent manufacturing processes and workflows created a more reliable product. By the Mk10, the Shrike took standard AEG barrels and hop rubbers. Issues with the complex composite hop assembly fracturing when torqued had been eliminated by use of like materials to aid adhesion, more robust geometry and fewer separate components being glued together.


The Mk10 in use in August 2020
The Mk10 in use in August 2020

In 2021, I was fortunate enough to have time, support and financial headroom to pursue this personal project with more dedication. I was in contact with professors at Imperial College London's business school, and with work quietening down during various stages of COVID lockdowns and tiered measures, I had the option to pursue a business venture from this idea.

Starting with the product I knew worked and had sufficient market demand, I focussed on bringing the Shrike from prototypes to commercial version. The first three months were spent redesigning the Shrike, analysing any custom components, and redesigning in a way that could use standard, off the shelf products or processes to achieve the same result. The hop unit again underwent a radical redesign, instead of using direct bonded, aluminium, steel and brass, soldered and brazed together, this was replaced by a machined sleeve, designed to take sections cut, extruded aluminium and steel tubing as inserts. This reduced the number of precision components from five to one, and made a fixed datum for all tolerances to then be referenced from, reducing complexity of accounting for tolerance stacking. This also allowed for the use of off-the-shelf AEG barrel clips to retain the barrel and hop rubber within the hop chamber, these again relying on the fixed reference points and comparatively higher precision of the barrel machining and the hop sleeve datum to ensure any barrel, from any supplier, would fit the Shrike and perform well. Several customers have since fitted aftermarket tight-bore barrels, longer, shorter, tracer units etc without any performance issues as a result of these changes. The M10 bolt retaining the folding mechanism was replaced by a ratcheting lever bolt, easier to adjust in a pinch, while remaining out of sight lines. The hopper itself was made removable. and received a pin-locking brace on the underside, allowing for bodyweight magnitude impacts without snapping, while improving serviceability. Use of finer thread on the adjustable hop-up mechanism allowed for a more precise adjustment and increased resistance to vibration. Screws were standardised to 12mm M3, button headed machine screws throughout, and the arrow piston itself became removable through the use of two 20mm dowel pins in the rear end of the cylinder.


The Mk12 hop unit, with precision machined sleeve and inserts. Mentioned retaining bolt and machine screws.
The Mk12 hop unit, with precision machined sleeve and inserts. Mentioned retaining bolt and machine screws.

Extensive testing later, and verifying the design changes had been an improvement, focus shifted to manufacturing at scale, and customer interaction. Marketing was launched, and a community mailing list gathered over 500 people worldwide who wanted to purchase a bow. Workshop effort moved towards producing cost effective bills of materials, order of operations and purchasing. Packaging was designed to support and display the Shrike, while mitigating the risks of poor quality courier services in the UK. Instruction manuals, documentation, compliance regulation and tax management all needed to be produced. By Summer 2021, the first batch of pre-production units was ready to go on sale.



An example parts diagram included in the instruction manual, including part codes for future servicing
An example parts diagram included in the instruction manual, including part codes for future servicing

12 units were released in the first round, enough to cover material costs for the first batch of products and the prototyping materials, for just under £200 each. All of these sold within 1 minute of the product going on sale. Most were within the UK but two went to Europe, and one ended up in the office of Airsoft International magazine, and later in the hands of Airsoft CamMan on Youtube.



These first 12 customers were of great help when approached for comments, with various improvements suggested about packaging, instruction and services, but for the most part, every customer loved the product, and reviews were incredibly supportive.



Review of the Shrike Airsoft Bow (pre-production) in Airsoft International in November 2021
Review of the Shrike Airsoft Bow (pre-production) in Airsoft International in November 2021



This gave me the backing I needed to release a full production run. And in late 2021, a further run of bows was released. Another few dozen units were made batch by batch and sold across the world. During this time I was approached by several companies across the UK, Europe and Asia to arrange licensing deals. The aspiration is the going forward these companies will be able to scale this product beyond what I am able to, producing and distributing the Shrike Airsoft Bow to any player that wants one, rather than the lucky, dedicated few who've received one so far.


Licensing arrangements are ongoing, and aiming to be finalised in early 2022...






Last Edited: 11th January 2022









Gallery:


The Shrike folded and slung while using a DMR on longer sight lines
The Shrike folded and slung while using a DMR on longer sight lines


Image credit from Airsoft Project, using one of the production run Shrike Airsoft Bows
Image credit from Airsoft Project, using one of the production run Shrike Airsoft Bows



A customer using the Shrike Airsoft Bow at the (credit) National Airsoft Festival
A customer using the Shrike Airsoft Bow at the (credit) National Airsoft Festival




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