Gun recoil and vibrating

[Karost]

I like to know how the gun solution will look like in SOB.

 

each gun type has difference gun solution that become a not easy job for developer.

 

do you thing gun recoil and vibrating will add to gun solution.

 

reference:

http://riseofflight.com/Forum/viewtopic.php?f=49&t=13078&hilit=Gun+recoil+and+vibrating

[FuriousMeow]

Your reference is three years old. Try out RoF now.

 

I don't know about SOB, but you should try out RoF rather than referencing something three years old that has definitely changed. Spray and pray will always be present online, rounds have a way of making their way to target if you throw enough in that direction so the method will still be used because no one dies and no one cares to conserve ammo.

[Karost]

@FuriousMeow 

I have no mean to  offense , I use key word search  "recoil vibrating"  and I found many good people out there testing gun model

I use this link to reference for sort out  the content about "recoil vibrating" modeling how it look like

 

 

then I come to my question about gun solution mobeling for SOB.

 

-.Should dispersion are dependency to vibration and recoil  modeling ?

- What difference for trajectory  between 20mm ShVAK  and MG 151/20 ?

- Are ammo in SOB simulate for velocity loss for every each 100m  range of fire ?

- tracer trajectory have a save curve like non-tracer rounds ?

 

These generate gas which helps to fill the low-pressure area at the base, reducing drag. This gives them a different trajectory by comparison with non-tracer rounds, not helped by the fact that as the tracer burns up the weight of the projectile reduces, thereby worsening its sectional density. Tracers can therefore never achieve a perfect match with other projectiles and can only ever be an approximate guide to their trajectory.

http://homepages.solis.co.uk/~autogun/ballistics.htm

 

major difference between SOB and ROF is  airplane speed.

Edited October 23, 2013 by karost

[Jaws2002]

Why would this be hard to model in a flight sim, made to work on a powerful gaming pc, when you can download a hundred balistic apps and calculators for thousands of cartridges and loads, that work on celphones?

 

Most loadouts are known, so it should be piece of cake to get the balistics right with today's technology.

[Sternjaeger]

..meanwhile, in the US, some serious R&D on the subject 

 

[HeavyCavalrySgt]

I think folks must have a lot of free time in Minnesota.

[BlitzPig_EL]

I think folks must have a lot of free time in Minnesota.

 

And a lot of spare change it would seem.

 

Wow.

[LukeFF]

SOB?

[Sternjaeger]

I suppose you've seen "Currawong", the Australian P-40  that shoots .50 cal blanks? Those guys know how to have fun! 

 

No recoil on this one of course, but helluva cool stuff nonetheless. It's particularly interesting to compare the difference between the muzzle flash with live fire and blank fire guns: with live fire majority of the powder is burnt inside the barrel, whilst with blanks most of the burning happens right outside the muzzle, giving the distinctive big cartoon/movie flash, something to keep in mind for the developers me thinks!

 

 

http://www.youtube.com/watch?v=Qmln5aChX0s

 

Edited October 24, 2013 by Sternjaeger

[Karost]

@Sternjaeger  that  is a good point for the flash light 

 

Now see this....

This is a history tracer gun  which we can see trajectory movement and vibration from it's self

and also see flash light from trance on day light .

 

 

 

Next, I hope some of you had play this  game before. It has only one thing to point out , that is a trance virtual effect from a B-17.

Tracer moving like hi-speed sneak  that look not realistic but feel  terrible when get close. 

 

 

Edited October 24, 2013 by karost

[FuriousMeow]

Tracers don't squiggle like that, it's the camera's vibration that causes that.

 

I assume you were referring to something else about trance and vibration, I just wanted to state that before it went any further with the tracer squiggle.

Edited October 24, 2013 by FuriousMeow

[Sternjaeger]

+1 to what FuriousMeow said

 

have a look at this live fire training video of P-39s. The difference here is that the camera is not on the aircraft, so there is no vibration induced by recoil, check out how straight the tracers are. Now the question is "what is more realistic?" the reply is on whether we want to look at the sim with "unbiased" eyes or with "camera" eyes..

 

http://youtu.be/sP2mMqR1ZFI?t=1m2s

Edited October 24, 2013 by Sternjaeger

[LukeFF]

Oh dear, let's not have a repeat of the tracer debate in the pre-CLoD release days. 

 

Tracers do NOT wobble. Period.

[Karost]

@Sternjaeger and @FuriousMeow Thank you for point out.

Seem I'm wrong about  vibration for tracer it self, sorry.

but what make the history video that I  posted look tracer "squiggle" ?

that come to my topic "Gun recoil and vibrating" make camera not stable and
some to the pilot ? and make pilot's visualization not stable when pull a trigger
while sitting on moving airplane and machine guns and cannon generate recoil .

 

That is my point.  that effect make pilot  not easy to aim and shooting fix gun to the target

at medium range!  

 

I'm not sure.

It will be good if any friends here who have a military experience shooting a gun
on helicopter or on plane or vihicle would like to share the idea. while other people

who stand on a ground see the difference.

Edited October 25, 2013 by karost

[FuriousMeow]

The difference is that eyes aren't on a solid mount, they sit a liquidy fleshy pink thing also known as the human body. It's a shock absorber. Additionally the brain compensates for vibrations and exterior forces - the key reason we aren't sitting in a corner cowering because the entire world around us vibrates our eyes out of our sockets each step we take is because our eyes sit in flesh that can absorb impacts and the brain itself compensates for everything.

 

Today's apex predators would be worthless and dead if their eyes worked like video cameras.

Edited October 25, 2013 by FuriousMeow

[LLv34_Flanker]

S!

 

 This eyes on dampers also negates a lot of vibration the plane does. At least that is how I felt it when flying in different planes from death traps like Cessna to a full bred warrior F/A-18D Realism vs playability is a tough one. I do not care how the tracers look as long as ballistics are done correctly.

[LukeFF]

 I do not care how the tracers look as long as ballistics are done correctly.

 

Well, I do, and the simple fact is that tracers do not wobble in-flight. It's the shaking of the camera that makes it look like they do, nothing more.

[ACG_Kraut]

I would definitely like to see the actually vibrations in the cockpit from recoil modeled, I've never really seen that done in a sim before.

 

For example here is a strafe in a modern Mig29. Notice how much all the instrument panel is affected by the recoil:

 

https://www.youtube.com/watch?v=WXxJTKOhSW4#t=95

 

Now keep in mind this is a modern jet built with modern tolerances and materials. Any WW2 aircraft should feel and look like it's going to rattle itself apart when firing cannons.

DCS has some of these vibrations modeled in the P51 and Huey for turbulence and whatnot, but it's not affected by recoil.

 

I think this would be an awesome feature to have the option to turn on (I know some people wouldn't want this and want to turn it off).

Edited October 26, 2013 by [AKA]Kraut

[Wind]

I would definitely like to see the actually vibrations in the cockpit from recoil modeled, I've never really seen that done in a sim before.

 

For example here is a strafe in a modern Mig29. Notice how much all the instrument panel is affected by the recoil:

 

https://www.youtube.com/watch?v=WXxJTKOhSW4#t=95

 

 

But there in that video we come back to the problem we have been discussing : How exaggerated the the movement is

when shot to the video VS what the pilot has seen.

 

As FuriousMeow said, human body, and especially the brain is just amazing in processing//stabilizing the image.

How it just skips information that is detrimental for percieveing and how it handles shapes,motion and recognition.

 

If you would ad that too much of information (shaking) to the game, it actually would be not only unrealistic but also really crappy

gameplay wise.

But, that said, some kind of recoil muted effect would be good for the gameplay and immersion, as the recoil affects the spread.

Which, by the way is allready in RoF and I had the impression that Il2 had it as well having flashbacks of firing the Mk 103...

[Sternjaeger]

That's a high rof big cannon sitting by the left elbow of the pilot, no wonder it shakes the whole house when you press the firing trigger!

 

I talked to several veterans who said that yes, you could feel the vibration, but the whole thing was also already vibrating because of the engine, and since they shot short burst the noise and vibration were quite muffled. But then again these were mustang and spitfire pilots, I bet FW190 pilots would have told you another story! :-)

[LLv34_Flanker]

S!

 

 LukeFF, I did not mention squiggly or not. I prefer them to look as they should, but more important to me is how ballistics are done. You do not shoot down planes with nice effects

[ACG_Kraut]

That's a high rof big cannon sitting by the left elbow of the pilot, no wonder it shakes the whole house when you press the firing trigger!

 

I talked to several veterans who said that yes, you could feel the vibration, but the whole thing was also already vibrating because of the engine, and since they shot short burst the noise and vibration were quite muffled. But then again these were mustang and spitfire pilots, I bet FW190 pilots would have told you another story! :-)

 

Ah yes, I did neglect to compare Piston vs Jet ambient vibrations.

 

I did some more research as well, I had assumed that the Mig29 had a 20mm cannon that you could compare to having a pair of say, MG151s. 

Well it turns out the Mig29 actually has a VERY HIGH RPM (15-1800 rpm) 30mm cannon, no wonder that thing shakes so much!

 

So, my Mig29 example is fairly exaggerated, but I still think there should be a similar effect to a lesser degree on BoS planes armed with a few cannons.

Edited October 26, 2013 by [AKA]Kraut

[Sternjaeger]

yeah man, the shaking will be there anyway I think.

 

If you look at the last video, when the view is looking back on the tail, you can see the canopy on the left vibrating, so I'm sure they'll implement this for shooting as well.

[LukeFF]

What?

[GOAT-ACEOFACES]

The vibration of the plane does not cause the stall as much as the force of the guns being in the opposite direction of the thrust which in turn causes the plane to slow down.

[Sokol1]

Tracers, like you see in game.

 

http://www.britishpathe.com/video/strafing-tactics/query/wildcard

 

Sokol1

 

 

[GOAT-ACEOFACES]

oh well I tried..

 

But before you disregard the FORCE of guns you may want to take a look at the video Sternjaeger provided starting at 1:00 where it shows a P51 moving backwards when the guns are fired..

 

And take note that the plane is strapped down.. yet it still managed to move!

 

Now take away the straps and the contact forces of the wheels on the ground, as would be the case during flight, and than you 'may' begin to get a 'feel' for the FORCES at play here.

 

Than go back and read your initial post where you stated the plane's speed is already near the stall, thus your velocity is near its min value, thus your momentum equation is near its min value, and therefore it would not take much FORCE in the opposite direction to slow the plane down past the stall point

 

Hope that helps! S!

Edited October 26, 2013 by ACEOFACES

[GOAT-ACEOFACES]

well if theres no friction of course its gonna move backwards  WHILE STOPPED

No friction?

 

Did you mean the drag forces?

 

ASSuming that you did

 

Re-read what I said and take note of where I pointed out the plane is STRAPPED DOWN and still managed to move.

 

Hope that helps! S!

[GOAT-ACEOFACES]

i didn't watch the video therefore i failed to see your point:

Fixed that for ya!

[Rjel]

This is a quote from the book PURSUE AND DESTROY by Leonard "Kit" Carson, an Eighth Air Force ace of the 357thFG. After the war he became an aeronautical engineer. I thought this quote was interesting as I've read many times how an airplane supposedly slowed when firing it's guns.   

 

"Incidentally, firing the guns did not noticeably slow the airplane down: the velocity loss was was less than one mile per hour. What the pilot felt was the vibration of the guns recoiling. When worked out, a P-51 weighing 9000lbs. and going 300mph (440 ft per second) has a kinetic energy of 27 million ft. pounds That of all the guns firing simultaneously (actually, they don't; they fire at random with respect to each other, but for our purposes, let's lump their kinetic energy together) is about 75,000 pounds. Thus the speed differentiation is negligible."

[Sternjaeger]

Raaaid please...  it is clear that recoil doesn't affect speed in noticeable way when a plane is flying, above all because nobody shoots long bursts, so let's move on please..

[Sternjaeger]

good man :-)

[GOAT-ACEOFACES]

my eductaed guess

No need to guess.. As I will show in the following.

 

As for the rest, I see most of you missed the point completely!

 

Go back and read raaaids initial post and note he was talking about a plane near the stall speed. Which is why my response to raaaid was about a plane near the stall speed.

 

That is to say talking about and/or providing examples of a WWII plane flying at 300+ mph and the corresponding 'small' effect on momentum does not relate to a WWII plane near stall speed.

 

The point in question is if you fire the guns while flying near the stall speed, can the force of the guns slow the plane down enough to exceed the stall speed. That is the question I answer in the following, where I show the plane's velocity is reduced by 17mph, which is enough to cause it to stall.

 

ASSUMPTIONS

15 second gun burst

50cal rate of fire ~670rpm (~11.167rps)

50cal weight ~0.102956lb (~0.0467kg)

50cal muzzle velocity ~3,000fps (~914.4mps)

P51D weight ~11,592lb (~5258kg)

P51D stall speed ~95mph (~42.4688)

P51D speed ~105mph (~46.939mps)

 

STATEMENT

Firing the guns of a P51 changed near the stall speed could reduce the speed to a point below the stall speed and cause the plane to stall.

 

CALCULATE

The P51's air speed after it fires a 15 second burst (~1,000 rounds)

 

We define 'the system' to consist of the mass of the P51 and the mass of the 50cal rounds. To begin we 'sum' the P51's momentum and the 50cals momentum.

 

d/dt[sum(mVP51 + mV50cal)] = sum(Fthrust + Fdrag)

 

INITIAL CONDITION (t < 0)

An event is a change from some initial condition to a final condition. Initially the P51 and the 50cals move horizontally at same constant speed : t < 0

 

In level flight when thrust ~= to drag, velocity and momentum are constant prior to firing the guns.

 

0 = sum(Fthrust + Fdrag)

 

The above equation tells that prior to firing the guns, the system momentum is zero in two ways.

1) Left-of equality says "the bullets and aircraft speeds are constant."

2) Right-of-equality says "thrust equals drag."

 

TRIGGER TIME aka EVENT (t > 0)

The six M2 guns are triggered for a burst of 15 seconds, which results in about 1,000 rounds being fired. To use the momentum equation we write it in general and consider it at the time : t = 0

 

d/dt[sum(mVP51 + mV50cal)] = sum(Fthrust + Fdrag)

 

All Forces of the event are notated. The 50cal mass and P51 mass are all part of the system. Forces of the momentum equation are effects of the surroundings.

 

To proceed toward solution of the first order differential equation, we separate variables then apply the integration operator:

 

Int(d[sum(mVP51 + mV50cal)]) = Int(sum(Fthrust + Fdrag))dt

 

The right of equality integrand of (Fthrust + Fdrag) was zero before change started : t < 0. To simplify the math we ignore any of the small changes and assume that the sum of these forces remain zero after the 15 second burst. The left of equality integrates immediately.

 

sum(mVP51 + mV50cal) = 0

sum([mVP51 + mV50cal](t>0) - [mVP51 + mV50cal](t<0)) = 0

 

The summation is required - our system has two components. Now we expand the sum.

 

(m2_P51*v2_P51 + m2_50cal*v2_50cal) - (m1_P51*v1_P51 + m1_50cal*v1_50cal) = 0

 

DO THE ALGEBRA

Now solve the above equation for v2_P51

 

(m2_P51*v2_P51 + m2_50cal*v2_50cal) - (m1_P51*v1_P51 + m1_50cal*v1_50cal) = 0

m2_P51*v2_P51 + m2_50cal*v2_50cal = m1_P51*v1_P51 + m1_50cal*v1_50cal

m2_P51*v2_P51 = m1_P51*v1_P51 + m1_50cal*v1_50cal - m2_50cal*v2_50cal

v2_P51 = (m1_P51*v1_P51 + m1_50cal*v1_50cal - m2_50cal*v2_50cal)/m2_P51

 

DO THE MATH

Now lets apply some values and see how much slower the P51 is going after the 15 second burst

 

mass_P51 = 5258.06 % 5258.06kg = 11,592.05lb

mass_50cal = 0.0467 % 0.0467kg = 0.102956lb

n_50cals = 6 % number of 50cals on a P51

n_fire_time = 15 % pull trigger for 15 seconds

rof_50cal = 11.167 % 11.167rps = 670rpm

n_rounds_fired = n_50cals*n_fire_time*rof_50cal % number of rounds fired

 

% t<0

m1_P51 = mass_P51 % t<0 mass of P51

v1_P51 = 46.939 % t<0 velocity of P51 where 105mph = 46.939mps

m1_50cal = mass_50cal*n_rounds_fired % t<0 mass of 50cals in kg

v1_50cal = v1_P51 % t<0 velocity of 50cals

 

% t>0

m2_50cal = m1_50cal % t>0 mass of 50cals same as T1

v2_50cal = 914.4 % t>0 velocity of 50cals aka muzzle velocity of 3,000fps = 914.4mps

 

RESULT

Plugging these values into the equations

 

v2_P51 = ~88mph

 

Note the velocity of the P51 prior to pulling the trigger was 105mph, and after the 15second burst it is ~88mph.

 

That is a difference of ~17mph.

 

Assuming the stall speed of the P51 is around 95mph, that means you would have stalled the P51 if you pulled the trigger for 15 sec when flying at 105mph.

 

Hope this helps!

Edited October 27, 2013 by ACEOFACES

[FlatSpinMan]

Yeah, I was going to say the same thing.

[GOAT-ACEOFACES]

S!

[FlatSpinMan]

A victory for decency and rationality.

[GOAT-ACEOFACES]

anyway my critic to you is that you overcomplex the problme making it confusing

over complex?

 

We will have to agree to disagree in that IMHO these are basic momentum calculations.

 

sorry ace but i think the overcomplexity of your calculation confused me

Fixed that for ya!

 

i promised i made the calculation to back you up but they didnt

 

can you spot anything wrong in my numbers?

So, you tried to plug in the values I provided and didn't get the same answer?

 

Ok, instead of me trying to find the error in your steps, allow me to show you the steps, i.e.

 

% defines

n_fire_time = 15sec

n_50cals = 6

rof_50cal = 11.167rps

mass_50cal = 0.0467kg

vel_50cal = 914.4mps

 

% calc number of rounds fired

n_rounds_fired = n_50cals * n_fire_time * rof_50cal

n_rounds_fired = 6 * 15sec * 11.167rps

n_rounds_fired = 1005.03

 

% calc total mass of 50cals fired

m1_50cal = mass_50cal * n_rounds_fired

m1_50cal = 0.0467kg * 1005.03

m1_50cal = 46.934901kg

 

% t<0 aka time 1

m1_50cal = 46.934901kg

v1_50cal = 46.939mps

m1_P51 = 5258.06kg

v1_P51 = 46.939mps

 

% t>0 aka time 2

m2_50cal = 46.934901kg

v2_50cal = 914.4mps

m2_P51 = 5258.06kg - 46.934901kg = 5211.125099kg

v2_P51 = ?

 

% plug above values into following equation

v2_P51 = (m1_P51 * v1_P51 + m1_50cal * v1_50cal - m2_50cal * v2_50cal) / m2_P51

v2_P51 = (5258.06kg * 46.939mps + 46.934901kg * 46.939mps - 46.934901kg * 914.4mps) / 5211.125099kg

v2_P51 = (246808.07834kgmps + 2203.077318039kgmps - 42917.2734744kgmps) / 5211.125099kg

v2_P51 = (246808.07834kgmps + 2203.077318039kgmps - 42917.2734744kgmps) / 5211.125099kg

v2_P51 = (206093.882183639kgmps) / 5211.125099kg

v2_P51 = 39.5488mps = 88.468mph

 

so what side is right i think it actually depends a lot on the weapons, you did a bad pick with the p51

No, right is right.

 

Be it a 50cal or a 30mm cannon, both can affect the velocity of the plane

 

Just one more than the other.

 

On that note, that is why I picked the P51 with 50cals instead of a plane with cannons. In that had I done so, I am sure that some here would have accused me of picking a plane with cannons because the effect is more noticeable. But, as I have shown, even the little 50cals can affect the speed.

 

If you need help, feel free to PM me and we can talk privately instead of spaming this thread anymore than it already has been.

Edited October 27, 2013 by ACEOFACES