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Revision as of 10:16, 24 September 2007

Executive Summary

Our team has performed an extensive analysis of the Well's L96 Airsoft gun. The major topics that are examined are the customer needs, the system functionalities, a list of components, a preliminary analysis of the manufacturing process, environmental impact, and failure modes. With regards to the customer needs, we agreed that the purpose of an airsoft is for gaming and emulation purposes. A detailed account of the airsoft's functionality that includes every step from loading the magazine to the firing the BB through the barrel is noted in our report. A preliminary analysis of DFMA, FMEA, and DFE was also performed and the opportunities for improvements were highlighted. Finally, a mechanical analysis of the trigger assembly was done.

Product Study

In this section, we will examined the purpose, customer needs, functionality, input/output, user groups, and stakeholders other than or customer with regards to our product.

Purpose of Product

The purpose of an airsoft gun encompasses four categories: target practice, training, entertainment, and crime. Target practice and training are oftentimes similar practices. Airsoft guns are used as training tools by the military and the police as airsofts emulate the mechanisms of a real gun. Another popular use for airsofts is for entertainment purposes. Airsoft games are hosted regularly. Finally, airsofts may be used for crime. Since an airsoft gun resembles the actual gun that it is modeled after, once the orange cap is remove or painted metallic, airsoft guns may be mistaken for an actual gun and may be used for malicious intent. As a result, there are legislations regulating the use of airsoft guns in certain localities.

Customer Needs

Airsoft guns are built with two purposes in mind: functionality and emulation. Customers who buy the Well L96 are expecting an airsoft gun that behaves as a sniper rifle should. They will expect the gun to be powerful. Airsoft players with more powerful guns gain a tremendous distance advantage especially in outdoor arenas. An airsoft gun shooting with a muzzle velocity of 300 ft/s has an effective range of 150 ft while as guns that shoot 450 ft/s have effective ranges of over 200 ft. Of course, power is not the ultimate measure of a sniper rifle. A powerful gun is useless if it is not accurate. Customers will reasonably expect an airsoft sniper rifle to be accurate enough to hit a human sized targets at long distances (200 ft). In addition, customers need a durable gun. Durability involves building a gun that can handle environmental fatigue such as excessive sunshine, cold weather and rain. Since airsoft is a physical activity, it also means building a gun that will not break because a player mishandled his gun while doing a physical action such as diving for cover. Finally, the customer has safety concerns that must be addressed. Shooting an airsoft gun can be dangerous if it is misfired. The gun needs to have at least one kind safety mechanism.

Functionality aside, customers buy airsoft guns because of how well an airsoft gun emulates the actual gun. When owning the actual gun is too expensive or is illegal (i.e. Japan), customers buy airsoft guns as substitutes. The most important aspect of emulation is how well the airsoft gun resembles the actual gun. How heavy the airsoft gun is in comparison to the actual gun is also important.

Functionality

Firing this airsoft gun starts with loading BBs into the magazine. Oftentimes, a tool called a "speed loader" is used to aid in loading. As BBs are loaded, a spring in the magazine becomes compressed. The loaded magazine is then inserted into the bottom of the gun. When the magazine is inserted into the gun, the compressed spring pushes the BBs to the top of the magazine and releases a single BB into the gun's loading chamber every time it is cocked to be fired. With ammo ready, the shooter rotates and then pulls the bolt handle back. This pulls back the bolt which then compresses a spring. At a certain pull back distance, which is approximately as far back as the bolt can be pulled back, a knob inside the catches a notch on a piston inside the bolt. This knob will hold the compressed spring in place. The bolt is slid back forward and rotated back to its original position, after which, the gun is loaded and potentially ready to fire. The safety switch, which should be in the "safe" position when not in use, is then switched to the firing position by sliding it forward. The "safe" position is indicated by the safety switch covering the red dot marked on the side of the gun, and the firing position is indicated by a visible red dot. Then, the shooter will pull the trigger to shoot the gun. There is an additional safety on the trigger. Its appearance is a smaller trigger on the main trigger, and it must be pulled back with the main trigger in order for the gun to fire. Pulling the trigger releases the previously mentioned knob from standing up. It releases from the notch in the piston. As a result, the spring will expand quickly. This quick movement pushes the piston forward creating air pressure. The resulting air pressure enters the loading chamber through a nozzle and propels the BB through the barrel.

The Well L96 is classified in airsoft terminology as a spring gun.

Inputs and Outputs in Terms of Materials, Energy, and Information

Material Input: magazine, BBs
Material Output: BBs at high velocity
Information Input: Direction of target
Energy Input: Energy to cock barrel, energy to pull trigger
Energy Outputs: Heat, noise
Other Output: Pain

User Groups Who May Dave Different Needs

Kids and adults

Airsoft guns are toys for kids; adults consider airsofts to be training/practice weapons.

Left-handed and right-handed people

People with different heights and different arm lengths

Guns are designed to be one-size-fit-all but different people like different lengths of stock and lengths of barrel.

Indoor and outdoor play

If the airsoft is for indoor target practice, it does not need to be as durable and as rugged as an outdoor airsoft gun.

Other Stakeholders

Other entities that have an interest in airsoft guns include:

Manufacturer of the airsoft guns
Companies that product the original gun that the airsoft is modeled after
Local/state/national/international governments
Concerned parents
Raw materials suppliers
Retailers

Assembly

Part	Name	Qty.	Weight	Function	Material	Maunfacturing Process
Trigger Assembly
T 01	Safety Switch	1	5 g	Toggles trigger safety	Steel	Casting
T 02	Screw for Safety Switch	2	< 1 g	Holds safety switch (T 01) to trigger assembly	Aluminum	Purchase
T 03	Brass Pin	1	< 1 g	Holds safety switch (T 01) in one of two positions	Brass	Lathing
T 04	Spring for Brass Pin	1	< 1 g	Keeps pressure on the brass pin (T 03)	Aluminum	Purchase
T 05	Bolt	3	< 1 g	With a nut (T 06), keeps trigger assembly case together	Steel	Purchase
T 06	Nut	3	< 1 g	With a bolt (T 05), keeps trigger assembly case together	Steel	Purchase
T 07	Left Housing	1	14 g	Left side of trigger assembly casing	Plastic	Injection Molding
T 08	Right Housing	1	13 g	Right Side of trigger assembly casing	Plastic	Injection Molding
T 09	Trigger	1	15 g	Activates firing mechanism, includes a mechanical safety	Aluminum	Casting
T 10	Pin	3	< 1 g	Allows rotation of T 09, T 12, T 18	Aluminum	Extruding/Purchase
T 11	Spring for Trigger	1	< 1 g	Keeps pressure on the trigger (T 09) to help it return to its standard position	Aluminum	Purchase
T 12	Lever	1	8 g	Rotation of lever caused by trigger releases piston release (T 18) to fire gun	Iron	Casting
T 13	Spring for Lever	1	< 1 g	Keeps pressure on lever (T 12) to return it to its initial horizontal position	Aluminum	Purchase
T 14	Bolt Safety	1	6 g	Slides vertically based on the rotation of the bolt (B xx) and activates a trigger safety	Iron	Casting
T 15	Spring for Bolt Safety	1	< 1 g	Keeps pressure on bolt safety (T 14) to keep it in position	Aluminum	Purchase
T 16	Bolt Safety Lock	1	2 g	Pushed horizontally by the bolt safety (T 14) to block the lever (T 12) from rotating, acting as the trigger safety	Iron	Casting
T 17	Spring for Bolt Safety Lock	1	< 1 g	Keeps the bolt safety lock (T 16) pressed against the bolt safety (T 14) to maintain the function of the safety	Aluminum	Purchase
T 18	Piston Release	1	3 g	Rotates when released by the lever (T 12), releasting the piston (B xx)	Iron	Casting
T 19	Radial Spring	2	< 1 g	Keeps and returns the piston release (T 18) to a centered vertical position	Aluminum	Purchase
T 20	Locking Pin	1	27 g	Locks the spring inside the bolt assembly in position	Aluminum	Casting
T 21	Trigger Assembly Screw	2	< 1 g	Attaches the trigger assembly to the barrel assembly	Steel	Purchase
Stock Assembly
S 01	Left Side of Stock	1	290 g	Cosmetic outer casing	Plastic	Injection Molding
S 02	Right Side of Stock	1	282 g	Cosmetic outer casing	Plastic	Injection Molding
S 03	Short Bolt	4	< 1 g	Cosmetic	Steel	Purchase
S 04	Long Bolt	6	2 g	Holds the left and right sides of the stock together	Steel	Purchase
S 05	Cover Nut	10	1 g	Cosmetic, spacer for long and short bolts (S 03 and S 04)	Aluminum	Casting and Milling
S 06	Lock Nut	6	1 g	With the long bolt (S 04) holds the left and right sides of stock together	Aluminum	Casting and Milling
S 07	Front Bipod Mount	1	164 g	Provides a mount for a bipod and holds the front sling catch (S 08) in place	Iron	Casting
S 08	Front Sling Catch	1	21 g	Provides a latch on both the left and right sides of the gun for a sling	Iron	Casting
S 09	Rear Sling Catch	1	15 g	Provides a latch on both the left and right sides of the gun for a sling	Iron	Casting
S 10	Rear Weights	2	171 g	Provides weight in the rear of the stock for balance and realism	Iron	Extruding and Cutting
S 11	Cheek Rest	1	34 g	Adjustable cheek rest used to rest cheek against when aiming and firing weapon	Plastic	Injection Molding
S 12	Cheek Rest Supports	2	11 g	Attached to the cheek rest (S 11) to allow vertical movement	Aluminum	Extruding
S 13	Internal Metal Frame	1	351 g	Attaches internally to the left and right sides of the stock and connects the stock to the barrel assembly via two bolts, as well as covering the trigger assembly	Casting	Iron
S 14	Bolt	2	7 g	Connects the stock assembly to the barrel assembly	Steel	Purchase
S 15	Lock Washer	2	1 g	Compresses to keep pressure on the bolt (S 14) and prevent loosening	Steel	Purchase
S 16	Washer	2	1 g	Allows lock washer (S 15) to rotate when bolt (S 14) is tightened without scraping the internal metal frame (S 13)	Steel	Purchase
S 17	Cheek Rest Holder Left Casing	1	10 g	Casing for cheek rest assembly, which locks the cheek rest assembly (S 11 and S 12) in position	Plastic	Injection Molding
S 18	Cheek Rest Holder Left Casing	1	10 g	Casing for cheek rest assembly, which locks the cheek rest assembly (S 11 and S 12) in position	Plastic	Injection Molding
S 19	Locking Bolt	2	5 g	With locking nut (S 20) locks the cheek rest assembly (S 11 and S 12) in adjustable position	Steel	Purchase
S 20	Locking Nut	2	2 g	With locking bolt (S 19) locks the cheek rest assembly (S 11 and S 12) in adjustable position	Steel	Purchase
S 21	Screws for Cheek Rest Assembly	7	< 1 g	Holds the left and right casing for the cheek rest holder together	Steel	Purchase
S 22	Butt Stock Weight	1	116 g	Provides weight in the rear of the gun	Iron	Extruding and Cutting
S 23	Butt Stock Front Plate	1	30 g	Provides spacing for rear butt stock, holds the butt stock weight (S 22)	Plastic	Injection Molding
S 24	Butt Stock Middle Plate	1	19 g	Provides spacing for rear butt stock	Plastic	Injection Molding
S 25	Butt Stock Rear Plate	1	18 g	Provides spacing for rear butt stock, provides structure for inside of butt stock rubber	Plastic	Injection Molding
S 26	Butt Stock Rubber	1	56 g	Creates a softer surface on the back of the gun for more comfort when aiming and firing	Rubber	Molding
S 27	Butt Stock Screw	2	< 1 g	Holds butt stock rubber to the rear butt stock plate (S 25)	Steel	Purchase
S 28	Butt Stock Washer	2	2 g	Provides a stronger surface for lock washers and bolts (S 31 and S 30) to tighten to than rubber	Steel	Purchase
S 29	Butt Stock Attachment Plate	2	13 g	Threaded hole in plate allows bolts (S 30) to secure butt plate assembly to the main stock assembly	Iron	Casting
S 30	Butt Stock Bolt	2	11 g	Fastens the butt stock assembly to the main stock assembly by screwing into the butt stock attachement plate (S 29)	Steel	Purchase
S 31	Butt Stock Lock Washer	2	1 g	Compresses to keep pressure on the bolt (S 30) and prevent loosening	Steel	Purchase
S 32	Low Ammunition Indicator	1	1 g	Pops up to notify user that there are no more BBs left in the magazine	Plastic	Injection Molding
S 33	Spring for Low Ammunition Indicator	1	1 g	Keeps pressure on the indicator (S 32)	Aluminum	Purchase
S 34	Low Ammunition Indicator Cover	1	1 g	Covers and prevents spring (S 33) from popping out, keeps indicator sliding in a vertically	Plastic	Injection Molding
S 35	Screws for Low Ammunition Indicator Cover	2	< 1 g	Fastens the indicator cover (S 34) internally to to the left side of the stock (S 01)	Steel	Purchase
Barrel and Bolt Assembly
B 01	Rail	1	88 g	Provides a place for a scope to be attached	Iron	Casting
B 02	Screws for Rail	2	< 1 g	Fastens the rail to the gun	Steel	Purchase
B 03	Barrel Cap	1	10 g	Covers the end of the barrel	Iron	ILathing
B 04	Barrel Cap - Orange	1	1 g	US Law mandates all airsoft guns shipped and sold have an orange tip	Plastic	Injection molding
B 05	Barrel Locking Pin	1	< 1 g	Prevents the barrel (B 06) from rotating while attached to the gun	Steel	Purchase
B 06	Outer Barrel	1	212 g	Houses the inner barrel	Steel	Lathe, mill
B 07	Magazine Latch Assembly	1	26 g	Contains a spring-loaded clip that holds the magazine in the gun	Iron	Casting
B 08	Magazine Latch Screw	1	< 1 g	Fastens the magazine latch assembly (B 07) to the gun	Steel	Purchase
B 09	Bolt Frame	1	464 g	Houses the bolt	Steel	Casting, Mill
B 10	Barrel Spacers	4	< 1 g	Supports inner barrel (B 19)	Foam
B 11	Hop Up Adjustment Screw	1	< 1 g	Adjusts how much pressure is placed on the bucking (B 17) via threading with the hop up adjustment ring (B 12)	Steel	Purchase
B 12	Hop Up Adjustment Ring	1	4 g	Adjusts hop up	Iron	Casting
B 13	Hop Up Adjustment Spring	1	< 1 g	Keeps upward pressure on the lever on the loading chamber (B 14) that pushes down on the hop up bucking	Aluminum	Purchase
B 14	Hop Up/Loading Chamber	1	54 g	Houses all of the hop up items and holds the BB in place while cocking the gun	Iron	Casting, lathe, mill
B 15	Barrel Locking Ring	1	4 g	Locks the barrel into the loading chamber (B 14)	Brass	Lathe
B 16	Washer	1	< 1 g	Helps Guide the BB properly into loading chamber	Brass	Lathe
B 17	Hop Up Bucking	1	< 1 g	Puts a backspin on BBs as they are fired	Rubber	Vulcanization
B 18	Spacer	1	< 1 g	Spacer for hop up bucking (B 17)	Plastic	Injection molding
B 19	Inner Barrel	1	114 g	Retains air pressure generated by piston so that the BB can accelerate, guides BB in straight path towards target	Brass	Molding, smoothing, hard anodizing
B 20	Rear Bolt	1	104 g	Keeps the bolt handle attached to the bolt assembly	Iron	Casting, mill
B 21	Screw for Rear Bolt	1	3 g	Fastens rear bolt (B 20) to the bolt assembly	Steel	Purchase
B 22	Bolt Handle	1	125 g	Allows shooter an easy way to pull back and cock bolt	Iron	Lathe
B 23	Nozzle	1	25 g	Concentrate and directs the air pressure generated by piston into the loading chamber (B 14)	Brass	Lathe
B 24	Nozzle O-Ring	1	< 1 g	Create an air tight seal between the nozzle (B 23) and the bolt cylinder (B 25)	Rubber	Molding, vulcanization
B 25	Bolt Cylinder	1	96 g	Houses the spring and piston assembly	Aluminum	Lathe, mill
B 26	Spring Guide	1	5 g	Makes sure the spring moves in one dimension	Plastic	Injection molding
B 27	Spring Guide Rod	1	10 g	Keeps the spring guide in position	Steel	Purchase
B 28	Spring for Spring Guide Rod	1	< 1 g	Keeps pressure on the spring guide rod to keep it in place	Aluminum	Purchase
B 29	Primary Spring	1	18 g	Compresses when bolt is pulled back and pushes piston assembly (B 30) forward producing air pressure to fire BB	Aluminum	Purchase
B 30	Piston Assembly	1	18 g	Pushed forward by primary spring (B 29) to generate air pressure with a seal produced by an o-ring	Plastic, rubber	Injection molding

Preliminary Analysis

FMEA

Item and Function	Failure Mode	Effects of Failure	S	Causes of Failure	O	Design Controls	D	RPN	Recommended Actions	Responsibility and Deadline	Actions Taken	S	O	D	RPN
Gun safety Prevents gun from misfiring	Fracture	Possibility of misfire	9	Pulling too hard	2	Stress analysis	3	54	Not likely, so ignore	Trigger assembly	-	9	2	3	54
Gun safety Prevents gun from misfiring	Jam	Inability to fire	8	Too much friction in pin slot	1	Specify slot tolerances	3	24	Not likely, so ignore	Trigger assembly	-	8	1	3	24
Bolt Cocks gun Additional safety	Jam	Inability to fire gun, inability to cock gun	8	Slots wear down	2	Fatigue testing	2	32	Not likely, so ignore	Bolt assembly	-	8	2	2	32
Bolt Cocks gun Additional safety	Improper loading	Gun will shoot a blank	5	Cocking the gun while it is upside down	5	Cocking test	1	25	Redesign and avoid gravity fed system	Bolt assembly	-	5	5	1	25
Trigger Fires gun	Fracture	Inability to fire gun	8	Pulling it too hard	2	Stress analysis	3	48	Not likely, so ignore	Trigger assembly	-	8	2	3	48
Secondary Trigger Additional safety	Jam	Possibility of misfire	9	Pulling it too hard	3	Stress analysis	3	81	Ignore since if this safety fails, there are two others	Trigger assembly	-	9	3	3	81
Barrel Increases muzzle velocity	Bending	Decreased muzzle velocity, inaccurate fire, inability to fire	8	Excessive stress	2	Stress analysis	3	48	No accident(s) will likely cause bending, so ignore	Barrel assembly	-	8	2	3	48
Stock Makes aiming easier	Fracture	Hard to aim gun	7	Excessive stress	1	Stress analysis	3	21	The stock is built tough enough that every other part of the gun will break before it does, so ignore	Stock assembly	-	7	1	3	21
Spring Powers the piston	Fatigue	Decreased muzzle velocity	5	Long term usage, keeping the gun cocked while stored	7	Fatigue testing	1	35	A reminder to NOT leave a gun cocked while in storage should be included in the user manual	Barrel assembly	-	7	5	1	35
Piston Generates air pressure to propel BBs	Broken air seal	Decreased muzzle velocity	5	Rubber piston head wears down	2	Fatigue testing	2	20	Any erosion won't significantly affect muzzle velocity, so ignore	Barrel assembly	-	5	2	2	20
Piston Generates air pressure to propel BBs	Excessive friction	Decreased muzzle velocity	5	Piston improperly lubed	2	Piston testing	3	30	Not likely, so ignore	Barrel assembly	-	5	2	3	30
Magazine Stores and loads ammo into barrel	Spring fatigue	Ammo will not load	8	Long term usage, storing ammo while not in use	2	Fatigue testing	1	16	Not likely, so ignore	Magazine assembly	-	8	2	1	40

Most considered failure modes were so unlikely that they are not worth a redesign. For instance, a broken gun safety is a severe product failure that may result in gun misfire. However, the likelihood that a consumer will break it during normal usage is extremely low. The most pressing failure mode is fatigue of the piston spring caused by having the gun cocked while it is stored. This can be alleviated by advising the consumer to uncock it while not in use.

Design for Manufacture and Assembly

Certain indications show that the Well's L96 Airsoft gun is designed with manufacturing and assembly in mind.

Design for Environment

Since the Well's L96 Airsoft gun is a complex piece of machinery to understand its environmental impact a life cycle assessment needs to be performed. A process LCA is beyond the scope of what is feasible for our project so an Economical Input Output Life Cycle Assessment was performed instead. EIO-LCA uses aggregate sector-level data to determine how much environmental impact can be attributed to each sector of the economy. Our market sector is small arms. From the 1997 benchmark input output, not specified by kinds small arm represents less than 10 percent of the small arms commodity output. Airsoft guns are mostly mainly composed of plastics whereas a professional firearm is normally made from metals. Therefore, the EIO-LCA is not a good benchmark for the impact of an airsoft gun.

Possible environmental improvements include but are not limited to:

lessening the number of parts in the design
increasing lifespan of product by producing a more durable and maintainable product
making modular parts so that worn or broken parts can be replaced
using biodegradable BBs
improving the distribution of airsofts

Opportunities for Improvements

The following are ideas for improvements that we might implement.

Turn the Well's L96 Airsoft gun into a hybrid electric gun.

A hybrid electric gun would have more functionality as it would allow for the user to switch between electric and bolt action. There are certain regulations in airsoft games that prevent a sniper gun from being fired at a close distance. An automatic electric gun would allow for the user engage in more close combat action.

Implement a burst fire mode

A burst fire is a firing mode that allows for a predetermined number of BBs to be fired with a single pull of the trigger.

Ergonomic improvements

Possible ergonomic improvements include adding a left-handed loading option. The Loading time of the BBs into the magazine should also be decrease. Plans to move the magazine closer is another possiblity.

Shorten/lengthen the length of barrel
Improve accuracy and speed of BB leaving the barrel
Reduce environmental impact
Reduce cost

Product Usage

Mechanical Analysis

Assumptions:

No mechanical failure due to stresses in materials
Small angles of rotation
Friction is negligible
Ideal spring loading
Any other assumptions not listed here will be addressed when the issue arises

The trigger assembly is composed of the trigger, a rotating lever, the piston release, and a mechanical safety. When the safety trigger and the primary trigger are pulled, the lever is pushed and rotates such that the piston release, which would have pressure being applied on it by the compressed spring in the bolt assembly, is released and is free to rotate. The vertical displacement of the right end of the lever must be 2mm downward for this release to occur, meaning the vertical displacement on the left side must be proportional to the lever arms. This ratio is 33mm/26mm = 1.27, meaning the displacement on the left must be 2.54mm.

F_T is the force between the trigger and the lever.
F_frame is the force applied by the frame on the trigger. This keeps the trigger in equilibrium when there is not enough force to rotate the trigger. This value is zero when the trigger force passes some critical value. For these calculations, F_frame = 0.
F₁ is the force applied by the trigger spring due to its compression. This spring is initially compressed 1mm.
F₂ is the force applied by the lever spring due to its compression. This spring is initially compressed 1mm.
F is the force applied at the middle of the curved portion of the trigger.

d_T is the moment arm for F_T about point O. d_T = 33 mm
d_t is the moment arm for F_T about point P. d_t = 7 mm
d₁ is the moment arm for F₁ about point P. d₁ = 10 mm
d₂ is the moment arm for F₂ about point O. d₂ = 20 mm
d_frame is the moment arm for F_frame about point O. d_T = 13
d is the moment arm for F about point P. d = 25 mm

(insert calculations here)

From measured values, the force required to pull the trigger averaged out to 2.44N over ten trials. Also measured was the safety trigger pull, which averaged out to 0.44N over ten trials. This extra force is required to compress the spring inside the trigger that pushes on the safety trigger. Therefore, the actual force to pull the trigger is about 2.00N.

Links

http://www.airsplat.com/Items/AR-WELL-MB01BSB.htm
http://en.wikipedia.org/wiki/Airsoft
http://www.airsoftgunhelp.com/airsoft-games.htm

@@ Line 1,069: / Line 1,069: @@
 = Mechanical Analysis =
+Assumptions:
+* No mechanical failure due to stresses in materials
+* Small angles of rotation
+* Friction is negligible
+* Ideal spring loading
+* Any other assumptions not listed here will be addressed when the issue arises
+<br />
+The trigger assembly is composed of the trigger, a rotating lever, the piston release, and a mechanical safety.  When the safety trigger and the primary trigger are pulled, the lever is pushed and rotates such that the piston release, which would have pressure being applied on it by the compressed spring in the bolt assembly, is released and is free to rotate.  The vertical displacement of the right end of the lever must be 2mm downward for this release to occur, meaning the vertical displacement on the left side must be proportional to the lever arms.  This ratio is 33mm/26mm = 1.27, meaning the displacement on the left must be 2.54mm. <br />
+[[Image:Airsoft_trigger_assembly.JPG|400px]] [[Image:Airsoft_trigger_pull.JPG|400px]]<br /><br />
+F<sub>T</sub> is the force between the trigger and the lever.<br />
+F<sub>frame</sub> is the force applied by the frame on the trigger.  This keeps the trigger in equilibrium when there is not enough force to rotate the trigger.  This value is zero when the trigger force passes some critical value.  For these calculations, F<sub>frame</sub> = 0.<br />
+F<sub>1</sub> is the force applied by the trigger spring due to its compression.  This spring is initially compressed 1mm.<br />
+F<sub>2</sub> is the force applied by the lever spring due to its compression.  This spring is initially compressed 1mm.<br />
+F is the force applied at the middle of the curved portion of the trigger.<br />
+d<sub>T</sub> is the moment arm for F<sub>T</sub> about point O.  d<sub>T</sub> = 33 mm<br />
+d<sub>t</sub> is the moment arm for F<sub>T</sub> about point P.  d<sub>t</sub> = 7 mm<br />
+d<sub>1</sub> is the moment arm for F<sub>1</sub> about point P.  d<sub>1</sub> = 10 mm<br />
+d<sub>2</sub> is the moment arm for F<sub>2</sub> about point O.  d<sub>2</sub> = 20 mm<br />
+d<sub>frame</sub> is the moment arm for F<sub>frame</sub> about point O.  d<sub>T</sub> = 13<br />
+d is the moment arm for F about point P.  d = 25 mm<br />
+[[Image:Airsoft_trigger_forces.JPG|400px]] [[Image:Airsoft_force_analysis.JPG|400px]]<br />
+(insert calculations here)
+<br />
+<br />
+From measured values, the force required to pull the trigger averaged out to 2.44N over ten trials.  Also measured was the safety trigger pull, which averaged out to 0.44N over ten trials.  This extra force is required to compress the spring inside the trigger that pushes on the safety trigger.  Therefore, the actual force to pull the trigger is about 2.00N.
 = Links =

Airsoft gun