Trajectory of MG151/20 vs Hispano Mk V

[Masherbrum]

Cause Allied bullets are over modeled

Now you've gone and done it!   

[RTHolmes]

although the Mk.V has slightly less energy, it has much higher RoF: 750rpm vs the Mk.II's 650rpm. this makes a huge difference in lethality. when I fly the C.205 it feels like its equipped with miniguns compared to the spits (mg151/20 is also 750rpm).

[Charge]

"I find the German weaponry devastating in this game when utilised in the correct manner."

I recall that HoHun concluded couple of years ago that from longer ranges the 151/20 probably suffers from modeling which cannot take into account chemical energy as such but only as a measure of kinetic energy.

BTW, gun lengths:

Hispano II: 250mm 
Hispano V: 220mm
MG151: 194mm
MG151/20: 177mm

-C+

[RTHolmes]

^ cm

[EagleDNY]

I don't think the ballistics are inaccurate on the MG151.  It would be nice if the damage and armor penetration of each of the various sorts of 20mm rounds was modeled, but I can see why HTC needed to model "average damage" and just go with it for simplicity's sake.  There is only so much programming time available per day, and modeling the difference in damage between the HE, HEI, API, and APHE rounds is probably way down the list of priorities.

The one problem I have always thought existed with the MG151 vs the Hispanos is in RATE OF FIRE.  I ran a stopwatch test on cannon ROF about 5 years back, and while the Hispano V was spot on at 750rpm, the Hispano II clocked in at 50rpm high (should be 600 rpm, but actually is 650 rpm) and the MG151s, using a much shorter 20mm round clocks in at 700 rpm in AH - well short of the 750-800 rpm listed in many sources.  The US Office of Chief or Ordnance, 1945 has the MG151 listed at 780rpm in their catalog of enemy ordnance.  The US Army T&TT has the MG151 listed at 750rpm with HE and 800 with AP rounds, but that is an 'estimate' from 1942, so I tend to think the Chief of Ord was probably the most accurate source, although they don't say what ammo the gun was tested with.  

See link:  http://www.lonesentry.com/ordnance/20-mm-m-g-15120-mauser-aircraft-machine-gun.html

[Shiva]

I don't think the ballistics are inaccurate on the MG151.  It would be nice if the damage and armor penetration of each of the various sorts of 20mm rounds was modeled, but I can see why HTC needed to model "average damage" and just go with it for simplicity's sake.  There is only so much programming time available per day, and modeling the difference in damage between the HE, HEI, API, and APHE rounds is probably way down the list of priorities.

What? You mean HTC doesn't have the free programmer time or server clock cycles to do a complete modeling of the damage for each round, including tracking the size, weight, shape, speed, and composition of each fragment an exploding shell breaks up into and how it might bounce around inside an airframe if it hits a structural member that it doesn't penetrate?

[Karnak]

One of the problems in games like this is that the advantages of the Hispano 20mm cannon or Browning .50 caliber machine gun are obvious, but their disadvantages are not nearly as apparent.  The reverse is true as well, the MG151/20 and Ho-5's advantages are hidden as they are in the same place as the weaknesses of the British and American guns.

Namely this, the Hispano and Browning HMG were heavy guns and weight is bad.  In addition, for the Hispano at least, the rounds are larger so you get fewer of them in a given space and they weigh more per round.  Imagine a Spitfire armed with two MG151/20s instead of Hispanos.  This Spitfire will climb and accelerate a bit better, perhaps bleed energy a tad slower and be slightly faster.  In addition it might have ~150-200 rounds for each cannon instead of 120.

In reality the flatter trajectory of the Hispano or Browning HMG wouldn't have been nearly as useful as hitting out past 250 yards was difficult and most often just a waste of ammo.  At 100 yards the muzzle velocity difference does not matter nearly as much.  There are reasons the Hispano Mk V is closer to the MG151/20 than the Hispano Mk II rather than heavier with a higher muzzle velocity and lower rate of fire.

[curry1]

One of the problems in games like this is that the advantages of the Hispano 20mm cannon or Browning .50 caliber machine gun are obvious, but their disadvantages are not nearly as apparent.  The reverse is true as well, the MG151/20 and Ho-5's advantages are hidden as they are in the same place as the weaknesses of the British and American guns.

Namely this, the Hispano and Browning HMG were heavy guns and weight is bad.  In addition, for the Hispano at least, the rounds are larger so you get fewer of them in a given space and they weigh more per round.  Imagine a Spitfire armed with two MG151/20s instead of Hispanos.  This Spitfire will climb and accelerate a bit better, perhaps bleed energy a tad slower and be slightly faster.  In addition it might have ~150-200 rounds for each cannon instead of 120.

In reality the flatter trajectory of the Hispano or Browning HMG wouldn't have been nearly as useful as hitting out past 250 yards was difficult and most often just a waste of ammo.  At 100 yards the muzzle velocity difference does not matter nearly as much.  There are reasons the Hispano Mk V is closer to the MG151/20 than the Hispano Mk II rather than heavier with a higher muzzle velocity and lower rate of fire.

Wouldn't the plane bleed energy faster as there is less kinetic energy becuase of the lighter weight?  I could be wrong and there is a reason for a lighter plane to retain energy if so could you please explain why that is.

[Karnak]

Wouldn't the plane bleed energy faster as there is less kinetic energy becuase of the lighter weight?  I could be wrong and there is a reason for a lighter plane to retain energy if so could you please explain why that is.

I was thinking in terms of bleeding E in a turn, not in a zoom climb.  It might bleed a bit more E in a zoom climb, although the better thrust to weight ratio might effectively counter that.  In a turn it would be carrying less weight into it and so should have less parasitic drag.

[Stoney]

Wouldn't the plane bleed energy faster as there is less kinetic energy becuase of the lighter weight?  I could be wrong and there is a reason for a lighter plane to retain energy if so could you please explain why that is.

You probably will want to take this question to a new thread so this one doesn't get totally derailed...

[curry1]

I was thinking in terms of bleeding E in a turn, not in a zoom climb.  It might bleed a bit more E in a zoom climb, although the better thrust to weight ratio might effectively counter that.  In a turn it would be carrying less weight into it and so should have less parasitic drag.

Oh I think I understand you.  Is it because an aircraft with less weight will lose less velocity in a turn becuase it takes less energy to turn a lighter aircraft?  So lighter aircraft come out of turns with more speed than a heavier craft?

[MK-84]

I would think that the shape of the projectile would have alot to do with it as well as weight like luche stated.  Anyone have a picture of each? 

[Stoney]

Oh I think I understand you.  Is it because an aircraft with less weight will lose less velocity in a turn becuase it takes less energy to turn a lighter aircraft?  So lighter aircraft come out of turns with more speed than a heavier craft?

The answer to the first question is "maybe" because your statement oversimplifies several important factors.  The answer to your second question is "no, not in the manner you describe".

[Karnak]

Yup, I said "perhaps" for a reason as I was just doing very crude estimations.  In no way am I promising the performance return I am guessing at.

The fact that I am talking about the same airframe, Spitfire with Hispanos vs Spitfire with MG151/20s, is the only reason I think such a crude estimation has a chance of being basically correct.