Can gun recoil really slow a fighter?

[Aozora]

The gun is but the firing barrel position is not. The barrels fire in the 9 o'clock position facing the aircraft.

That A-10 ain't gonna live long if the barrels fire while facing the aircraft...

 

[tyrodtom]

And you ain't going to live long if the barrels fire while you're facing the aircraft.

 

[CobberKane]

yes it is..i stand corrected. its been many years since i reloaded anything.

SR what speeds are the 51 and 47 flying at to get that rate of loss? i would think it would go on a curve...the slower the plane the more severe the loss and the faster it was travelling the less severe. like stopping a car. more resistance is needed for a car going 60 mph than 10. if i am reading your calculations correctly you just divided the impluse only to the weight of the plane alone...like it was sitting on the tarmac. or doesnt it matter what speed? i would think KE = 1/2 MV2 would have to figure in this somehow..

The loss of speed due to recoil would be the same, irrespective of the speed of the aircraft before the guns were fired. Shortrounds figures for the P-47 give us a rive us a de-accelleration of about 11 m/ps from a five second burst. So, while several long busts in quick succession might reach the 25-40 mph de-accelleration you spoke of earlier, on the whole you would have to think that the effect of recoil on a fighters speed was actually a lot less than suggested by seat of the pants impressions (given the way pilots talk of it). It seems to me that a pilot who was concerned about gun recoil pushing the fighter into a stall during hard manoeuvering would have had to have been right on the edge for this to be a risk.

 

[snelson]

I don't know where you got those weights, but the Barrett M82 weight is 31 lbs.
The M2 .50 cal heavy barrel is 83 lbs., just the weapon not including tripod.
The AN/M2 light barrel, used in WW2 aircraft weight was 61 lbs.

I'm don't think there is a direct corollation between gun weight and felt recoil, it's not that simple.

you are right about the weight of the M2 i was including the weight of the tripod which weights 127 lbs.

but even with the light air craft gun it would still cut the recoil by 1/2.

it's well known in the gun world that if the gun has to much recoil you make the gun heavier, twice the weight half the recoil. if you add the weight of the plane the recoil goes to almost nothing.

Recoil Calculator

here's a recoil calculator where you can punch in any set of numbers to help you find out how much recoil velocity you get.

 

[tyrodtom]

you are right about the weight of the M2 i was including the weight of the tripod which weights 127 lbs.

but even with the light air craft gun it would still cut the recoil by 1/2.

it's well known in the gun world that if the gun has to much recoil you make the gun heavier, twice the weight half the recoil. if you add the weight of the plane the recoil goes to almost nothing.

Recoil Calculator

here's a recoil calculator where you can punch in any set of numbers to help you find out how much recoil velocity you get.

And the the very site you posted says in the first sentence, the numbers calculated here DO NOT relate to felt recoil.

 

[pbehn]

Hi Guys my first pot although I've been lurking for months............great forum.

I think there are some errors here (though I may be wrong). The maximum recoil felt by the pilot would be when all guns fire at the same time in effect the weight is that of one bullet and charge 6 or 8 times larger the lowest recoil would be when they fire at different times equally spaced in a cycle (like the firing of the cylinders in an engine). In practice I'm sure there are millie seconds of difference. Some have averaged the weight of shot per second however I think to calculate the maximum this should be the weight x velocity of charge and bullets (muzzle velocity) / the time taken from firing to the bullet exiting the barrel.

When a plane is in level flight at maximum power and has achieved maximum peed all forces are in equilibrium. The recoil from the guns would introduce a new force eqivilant to an increase in drag, the plane would then slow down to a new equilibrium, it would not continually slow down or theoretically it would go from max speed to stall even on full power (I know no plane carries so much ammo).

As I was thinking of this I thought what is the effect of pumping large volumes of hot gas and particles into the airflow of (for example) a Mutang. The guns firing stained the wing so obviously this gas and particles are in the air directly in contact with the wing, would this increase drag?

The human body is very sensitive to forces, when a plane is in level flight not only are the forces on the plane balanced but also on the pilot if the plane slows by even 1/2 of 1 MPH instantaneously the pilot would feel it in the same way that those of us old enough to travel on old trains connected by chains felt a jolt as the slack on the train was taken up, in a small fraction of a second the train goes from standstill to maybe 1/2 a mph but it can give a helluva jolt. I imagine the sensation would be a bit like hitting standing water in a car.

An aircraft on the ground is hard to move but this isnt due to the weight but the rolling resistance of the tyres, suspend the same craft from a wire as in a museum and its a whole lot easier, a 10 ton fabrication on a crane can be easily be manouvered by one man. A plane in flight is free to move in reaction to forces acting upon it.

To answer the original post the guns firing must slow the aircraft, its the laws of physics. Would the pilot feel it? possibly I think although I think its possible the disturbed airflow may have more effect than the weight of the actual bullets. Many plane had the firing port covered with tape, therefore firing the guns immediately puts 8 holes in your early spit and hurricane leading edge, this must increase drag, the ground crews could hear the whistling noise when BoB planes came into land after firing their guns

 

[Shortround6]

Felt recoil it what your shoulder or hand feels

Let me whittle down the butt of rifle to about 1/2 it's original thickness so it hit's 1/2 of the shoulder area with the same force total and tell me how it "feels".

Or use rough checkered grips on a hand gun with raised edges to the checkering instead of smooth wood.

Or a lot of drop to a stock and a narrow, low comb so as the rifle/shotgun pivots up it smacks your cheek bone.

Punishment you feel has a lot more variables than just the velocity of the recoiling gun of the ft/lbs-jules of energy.

 

[GrauGeist]

you are right about the weight of the M2 i was including the weight of the tripod which weights 127 lbs.

but even with the light air craft gun it would still cut the recoil by 1/2.

it's well known in the gun world that if the gun has to much recoil you make the gun heavier, twice the weight half the recoil. if you add the weight of the plane the recoil goes to almost nothing.

Recoil Calculator

here's a recoil calculator where you can punch in any set of numbers to help you find out how much recoil velocity you get.

I have two shotguns, one is a Winchester model 12 and the other is a Remington squareback autoloader. Both have comparable barrel lengths and both are 12 gauge and can fire the same ammunition.

I can fire the Remington from the hip but I cannot do that with the Winchester. The reason is that the Remington is using the energy from the discharge to cycle the eject/load sequence while the Winchester simply discharges the round and waits for somebody to eject the shell and load a fresh one manually, so in this case, the energy is not being used but is driven right back to the shoulder instead.

So in the recoil world, it's not the weight of the gun, it's how it's designed.

 

[Shortround6]

If the guns weighs the same you have the same total recoil. In the Winchester you get it all at once, in a hundredth of a second. With the Remington you get it slowly. The Barrel moves back against a big spring compresses the spring. the gun picks up speed slowly as the spring compresses. The peak recoil force is much reduced but the total recoil force is unchanged.

Video :
View: https://www.youtube.com/watch?v=CDaWnO4s8Vo

Go to 5:29

This is one reason "felt" recoil is so variable.

10lbs is 10lbs wither it is on a table, a chair or sitting on a compressed spring.

 

[tyrodtom]

` I don't know what the percentages are, but some of the recoil energy is absorbed in working the action, moving the belt, stripping the round out of the links, feeding it into the chamber, ejecting the spent cartridge.
Plus the M2 had two buffer systems , a oil buffer that forced oil thru small passages, and disk buffers, both absorbed recoil, didn't just spread it out over time.
Both of these systems in the same weapon.

 

[Shortround6]

` I don't know what the percentages are, but some of the recoil energy is absorbed in working the action, moving the belt, stripping the round out of the links, feeding it into the chamber, ejecting the spent cartridge.
Plus the M2 had two buffer systems , a oil buffer that forced oil thru small passages, and disk buffers, both absorbed recoil, didn't just spread it out over time.
Both of these systems in the same weapon.

What did they do with the recoil energy? it just doesn't go away.

Some of it they turned to heat. the buffers heat up and yes the buffers spread out the time. They slow down the moving parts, they were there to minimize the internal parts battering themselves, not as recoil reducers for the gun. Take them out and the gun will speed up it's rate of fire. You will also wind up breaking parts much quicker.

The amount of energy used to 'work' the action is minimal.

 

[snelson]

And the the very site you posted says in the first sentence, the numbers calculated here DO NOT relate to felt recoil.

you are right again, there is noway to tell how something feels. what might seem lot to me may mean nothing to you. things like rubber butt pads and stock design help take the bite out of them.

here this site explains it better than i do.


Rifle Recoil Table

 

[bobbysocks]

you have the same amount of recoil force from the spent shell as it is moved in the opposite direction of the projectile... but the design of the some guns will dissapate that and use that energy to work mechanisms and thus bleed off that energy.

 

[snelson]

I have two shotguns, one is a Winchester model 12 and the other is a Remington squareback autoloader. Both have comparable barrel lengths and both are 12 gauge and can fire the same ammunition.

I can fire the Remington from the hip but I cannot do that with the Winchester. The reason is that the Remington is using the energy from the discharge to cycle the eject/load sequence while the Winchester simply discharges the round and waits for somebody to eject the shell and load a fresh one manually, so in this case, the energy is not being used but is driven right back to the shoulder instead.

So in the recoil world, it's not the weight of the gun, it's how it's designed.

if the shotguns weight the same, then amount of recoil energy will be the same. but the semi auto spreads the recoil velocity will be spread out over a longer time reducing felt recoil. the same thing happens when you add weight to the gun.

 

[bobbysocks]

What did they do with the recoil energy? it just doesn't go away.

Some of it they turned to heat. the buffers heat up and yes the buffers spread out the time. They slow down the moving parts, they were there to minimize the internal parts battering themselves, not as recoil reducers for the gun. Take them out and the gun will speed up it's rate of fire. You will also wind up breaking parts much quicker.

The amount of energy used to 'work' the action is minimal.

it depends on the design of the gun how timing is accomplished. if it fires from an open bolt....the bolt is in the rearward position until the trigger is pulled...the firing pin is fixed to the bolt head....the weight of the bolt and the return springs are proportional to the acceptable loads of the ammunition. too mild a load and the firearm will not cycle...too hot it will over compress the return.recoils springs and could damage the firearm.
if the firearm fires from the closed position and has a hammer it will need to be mechanically times so that the hammer is held back and not riding on the firing pin when the bolt slams the shell into the breech. if it didnt the potential for a slamfire or pre-ignition firing could occur. there is usually a system of levers that are actuated by the bolt at different stages.

a lot of the recoil force is absorbed in moving the bolt rearward and compressing springs.

 

[parsifal]

genuine question guys. i dont even know if this is possible....but what happens to the reactive forces on the aircraft once the shell has left the barrel? What if the potential energy locked away in the chemical reaction isnt fully realeased as the shell leaves the barrel. If only a part of the shells propellant has been spent, or the shell loses some of its weight as it leaves the barrel (such as with a discarding sabot round), would this not reduce the recoil effect on the aircraft?. I talking theoretically rather than practically initially.

 

[tyrodtom]

you are right again, there is noway to tell how something feels. what might seem lot to me may mean nothing to you. things like rubber butt pads and stock design help take the bite out of them.

here this site explains it better than i do.


Rifle Recoil Table

I'm not trying to deny that gun weight is a factor in recoil, especially in solid weapons like bolt action rifles, and revolvers.
But we're talking about automatic weapons here, and in them there are several other factors to consider also.

I've never fired a Barrett of any sort, but I have fired a M2 .50 cal, heavy barrel many times.
If you tried the same trick with a M2, as they did with that Barrett on the table. The M2, 83 lbs and all, would not stay on the table.

 

[CobberKane]

genuine question guys. i dont even know if this is possible....but what happens to the reactive forces on the aircraft once the shell has left the barrel? What if the potential energy locked away in the chemical reaction isnt fully realeased as the shell leaves the barrel. If only a part of the shells propellant has been spent, or the shell loses some of its weight as it leaves the barrel (such as with a discarding sabot round), would this not reduce the recoil effect on the aircraft?. I talking theoretically rather than practically initially.

It seems to me that recoil depends of two things; the amount of mass ejected from the barrel and the speed at which it exits. FELT recoil is also dependant on the mass of gun or gun/plane combination, but the actual energy of the recoil is constant. If some of the propellant left the barrel before combustion, it would not affect the mass leaving the barrel because mass is not consumed in a chemical reaction; the amount of material exiting the barrel would be the same. However, as the unburnt propellant did not contribute its energy to accelerating the projectile, recoil would be less for this reason. Many cartridges can be used in both hand guns and rifles, but as the short barrel of handgun means the round exits the muzzle before all the propellant is burned, a portion of the available energy is lost as muzzle flash after the propellant leaves the barrel and thus does not contribute to muzzle velocity or, by definition, recoil. Hence the recoil will be greater in the rifle, even though the cartridge is the same. FELT recoil may be greater for the handgun though, due to its lesser mass. I think.
In respect to the reciprocating parts of an automatic or fully automatic weapon reducing recoil, this must be the case, though by how much I wouldn't know. I believe bolt action rifles and revolvers typically have higher muzzle velocities than semi-automatic weapons, perhaps for this reason. I'm sure someone out there who is in to bench rest shooting could give us an idea of the different muzzle velocities of the same round fired from a bolt action and a semi auto (not me, semi autos are largely banned in Australia). For the effect on a fully automatic weapon I guess it would be easy enough to measure by disabling the mechanism for one round, then comparing muzzle velocity or recoil with that of a single round fired with mechanism in action.

 

[Shortround6]

It is Newtons 3rd law; The momentum of the "stuff" going out the muzzle HAS to equal the momentum of gun, mount, plane, ship.

Momentum is mass times velocity.

Now the "stuff" going out the muzzle may have different velocities. Projectile( and sabots leave at the same velocity as the cores, they just slow down much quicker upon leaving the muzzle), powder gases, unburned powder, still burning powder.

As for how much "power" is lost due to the action......not much. Most gas operated weapons have the gas port well down the barrel and the gas pressure has dropped considerably by the time the projectile passes the gas port. Pressure may have peaked at 50-65,000psi (depending on measuring system, I am old enough to think in copper crusher terms and not transducers) a few inches in front of the chamber but be down to 6-8,000psi at the gas port.

For a better explanation see; M1 Garand Gas Pressure

You can have a greater variation between otherwise identical rifles than the difference between a gas gun and a manual rifle.
Revolvers have a cylinder gap which bleeds off some pressure right away, but revolvers have a 'secret' advantage. A 4 inch revolver has 4 inches of barrel in front of the chamber/cylinder while a 4in automatic barrel has the chamber cut into the rear of the 4 inch tube. Mkae sure you are comparing like to like

 

[CobberKane]

It is Newtons 3rd law; The momentum of the "stuff" going out the muzzle HAS to equal the momentum of gun, mount, plane, ship.

Momentum is mass times velocity.

Now the "stuff" going out the muzzle may have different velocities. Projectile( and sabots leave at the same velocity as the cores, they just slow down much quicker upon leaving the muzzle), powder gases, unburned powder, still burning powder.

As for how much "power" is lost due to the action......not much. Most gas operated weapons have the gas port well down the barrel and the gas pressure has dropped considerably by the time the projectile passes the gas port. Pressure may have peaked at 50-65,000psi (depending on measuring system, I am old enough to think in copper crusher terms and not transducers) a few inches in front of the chamber but be down to 6-8,000psi at the gas port.

For a better explanation see; M1 Garand Gas Pressure

You can have a greater variation between otherwise identical rifles than the difference between a gas gun and a manual rifle.
Revolvers have a cylinder gap which bleeds off some pressure right away, but revolvers have a 'secret' advantage. A 4 inch revolver has 4 inches of barrel in front of the chamber/cylinder while a 4in automatic barrel has the chamber cut into the rear of the 4 inch tube. Mkae sure you are comparing like to like

On further consideration, it occurrs to me that the reciprocating parts in a machine gun or cannon would have effectively ZERO effect on recoil. Some of the energy from each round goes into re-cocking the weapon for the next round, but the movement of the reciprocating parts themselves would still pass on the energy to the aircraft as a whole. There might be some damping effect, but the deaccelleration would be unchanged.