WW2 Aircraft Gun Specifications

Discussion in 'Weapons Systems Tech.' started by Ivan1GFP, Dec 15, 2008.

  1. Ivan1GFP

    Ivan1GFP Member

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    Hello All,

    I remember seeing a spreadsheet that had details on many of the aircraft guns in WW2. This was intended for the CFS 1% aircraft. Does anyone still have that spreadsheet. The data I am looking for is the ammunition weight with disintegrating link belts.

    Thanks in advance.
    - Ivan.
     
  2. HoHun

    HoHun Active Member

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    Hi Ivan,

    >The data I am looking for is the ammunition weight with disintegrating link belts.

    I haven't seen the spreadsheet you're talking about, but here is the data I have (from RLM data sheets for the Luftwaffe weapons and some weight and balance sheets for the Allied weapons). If you find more, your additions would be appreciated! :)

    MK 108, 30x90RB: 585 g
    MK 103, 30x184B: 920 g
    MG 151/20 (MX), 20x82: 213,7 g
    MG 151/20, 20x82: 213,7 g
    Hispano V, 20x110: 246 g
    VYa-23, 23x152B: 230 g
    Hispano II, 20x110: 246 g
    MG-FF, 20x80RB: 338,3 g
    MG 151, 15x96: 182,2 g
    MG 131, 13x64B: 78 g
    ,50 Browning M2, 12,7x99: 110 g
    Browning ,303, 7,7x56R: 30 g
    MG 17, 7,92x57: 29,2 g

    (Fractional weights are the result of having different ammunition types mixed according to Luftwaffe practice. The weights here are a representative figure. Note that the data for the MG FF/M includes a fraction of the weight of the 60 round drum ... a bit awkward, but makes for better-though-not-perfect comparisons.)

    Regards,

    Henning (HoHun)
     
  3. Ivan1GFP

    Ivan1GFP Member

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    Hello HoHun,

    I was actually hoping that someone out there had the spreadsheet. I printed it out years ago but don't know where went.

    I am having LOTS of trouble verifying the numbers you quote. I just picked one gun, the .50 M2 Browning, that is so common that there should be LOTS of information.

    You listed a weight of 110 grams which I presume is one round and one link.
    The ammunition weights I have seen quoted are about 115 to 117.5 grams WITHOUT the link for Ball, Tracer and Incendiary.

    The book "The Machine Gun" by George Chinn lists a weight of 30.25 pounds for a 100 round link belt for a .50 Cal M2 MG. That works out to slightly over 137 grams per round with its link. This seems pretty close to the quoted weights of ammunition for a P-40E that I found.

    I was actually hoping to lay hands on a couple rounds of .50 Cal and links to weigh them to resolve the differences.

    - Ivan.
     
  4. HoHun

    HoHun Active Member

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    Hi Ivan,

    >You listed a weight of 110 grams which I presume is one round and one link.
    The ammunition weights I have seen quoted are about 115 to 117.5 grams WITHOUT the link for Ball, Tracer and Incendiary.

    Many thanks for pointing that out! I can't believe I missed that ... I've been using the 12.7 mm round as a point of reference all the time.

    Here is a Spitfire load and balance sheet ... it yields data for the 0.303" Browning and the 20 mm Hispano. I'll see if I can find something similar indicating the weight for the 12.7 mm ammunition!

    Regards,

    Henning (HoHun)
     

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  5. HoHun

    HoHun Active Member

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    Hi again,

    >I'll see if I can find something similar indicating the weight for the 12.7 mm ammunition!

    Here is a P-47 Weight and Balance Sheet ... it seems the ammunition including belting weighed 0.3 lbs per round.

    Regards,

    Henning (HoHun)
     

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  6. Elconaut

    Elconaut New Member

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    Here are weights as given in a WW II era manual. Sorry but no weight for the links are given.

    Per OS 9-18, November 1942, .50 cal. cartridge weights (approximate), in grains
    A.P., M2: 1822
    A.P., M1: 1869
    Ball, M2: 1813
    Ball, M1: 1873 (cartridge is limited standard and no longer manufactured)
    Tracer M2: - (not yet in quantity production)
    Tracer M1: 1789
    Incendiary: - (not given, details classified as confidential)

    Wikipedia:
    In many cultures, a grain is a unit of measurement of mass that is based upon the mass of a single seed of a typical cereal. Historically, in Europe, the average masses of wheat and barley grain were used to define units of mass. Since 1958, the grain or troy grain (Symbol: gr) measure has been defined in the International System of Units as precisely 64.79891 milligrams.[1][2] Thus, there are precisely 7,000 grains per avoirdupois pound in the Imperial and U.S. customary units. In fact, the grain is the only unit of mass measure common to the traditional three English mass and weight systems (avoirdupois, Apothecaries’, troy). Moreover, the measure for pearls and diamonds - the pearl grain and the metric grain - are equal to 1/4 of a (metric) carat, i.e. 50 mg (0.77 gr).
     
  7. Fokker D21

    Fokker D21 Member

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    Ivan1GFP, are you looking for info for Microsoft's Combat Flight Simulator 1?

    Things like dp values?
     
  8. Ivan1GFP

    Ivan1GFP Member

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    Hello Fokker D21,

    Yes, I am looking for values for calculating loads for CFS1 flight models. DP values would be nice too, but at the moment, weights are more important. I remember there was a spreadsheet for 1% aircraft out there and was hoping that someone had downloaded it and kept it. I printed at least one copy but can't remember where I left it.

    I have a hard copy of the Engine parameters sheet and have found errors on that one.

    Hello Elconaut,

    Yes I am familiar with grain weights. The are much more intuitive to me than grams. M852 - 168 grain HPBT. My typical load for 150 grain bullets for .30-06 was 48.5 - 49.5 grains of IMR 4895.

    Hello HoHun,

    I believe the numbers from your P-47 data sheet matches the weight quote I found fairly closely.

    Thanks all.
    - Ivan.
     
  9. Fokker D21

    Fokker D21 Member

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    I don't have load values. But on my website you can find values for Cartridge Power according to a formula designed by Tony Williams and a formula designed by me. The CP values are deliberately multiplied by a factor of 3 because I calculated them for correct DP values in CFS1.

    CFS1 overestimates the power of rifle calibre guns and underestimates the power of the bigger weapons. To give an example: a Hurricane with 8 Brownings .303 has more firepower than a Hurricane with 4 Hispano's II.

    To fix this a I kept the dp values for heavy calibre machine guns more or less the same, the rifle calibre goes down, the 20 and 30 mm go up.
     
  10. Ivan1GFP

    Ivan1GFP Member

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    Hello Fokker D21,

    I guess I know who you are then. I am pleased to virtually meet you.
    My goal at the moment is to work on flight models. In order to do this, I need accurate weight values for the aircraft. In CFS, this would be the "Zero Fuel Weight". I am looking for numbers for the disposable loads in the aircraft and having an accurate weight for ammunition helps.

    Per the earlier discussion, There is no point in calculating in the weight of the ammunition drum unless the drum is discarded off the aircraft when it is empty. (Does the same thing apply to links for a bomber's gun stations?)

    I had not thought that the CP value was really a CFS DP value, but will review the numbers in that light.

    Thanks.
    - Ivan.
     
  11. Ivan1GFP

    Ivan1GFP Member

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    Hello again Fokker D21,

    This may be in the wrong forum, but if you are into CFS1, have you ever tried out the stuff I built? If so, what do you think?

    - Ivan.
     
  12. Fokker D21

    Fokker D21 Member

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    I'm sorry but I was into CFS 1 some years ago. But by today standards the game is outdated. Furthermore I don't really like the modelled flight behaviour in the game. The Hurricane for instance practically never stalls and can be flown with max stick. Pulling back the stick completely on a Fw 190 means inmediate stall at any speed. I also refuse to believe that any plane is unstable in pitch (no matter how much you reduce or increase throttle to maintain altitude). Watch what happens to a plane with autopilot set to maintain altitude.

    I tried to tinker with the aircraft variabeles, but they were to complex to understand and cannot solve the above mentioned problems.
     
  13. Fokker D21

    Fokker D21 Member

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    As far as I know the remaining empty links in bombers were taken back to base with the bomber (Italian bombers even had special trays to collect these). Only in emergency (an engine taken out) would all excess weight be tossed overboard.
     
  14. Ivan1GFP

    Ivan1GFP Member

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    Hello Fokker D21.

    Sounds like you are right regarding discarding links. If that is the case, then from a disposable weight standpoint, the ammunition on a bomber gun station is lighter than the same ammunition on a fighter.

    BTW, I don't disagree with you regarding CFS stock aircraft. It IS an older simulator, but I believe there are a couple of us that have done some pretty good work on add-on aircraft. I host my stuff at Sim-Outhouse. I believe my flight models are a substantial improvement over the stock ones. Let me know what you think. Also there are a whole bunch of aircraft that I have not yet released yet because I am still working on them. If you are interested, I'll send you some of them as trial only (don't distribute).

    Aircraft CAN be unstable in pitch, but the problem that you are describing isn't that. It is because the trim effect per notch in the flight model is too small. The autopilot can't adjust the trim fast enough to keep up with aircraft pitch and the result is a divergence. I try to adjust the trim to work with autopilot but the problem there is that if the notches are too large (works with Autopilot), then sometimes the fine tuning to keep the plane absolutely level cannot be done. (Phugoid?)

    - Ivan.
     
  15. HoHun

    HoHun Active Member

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    Hi Ivan,

    >Per the earlier discussion, There is no point in calculating in the weight of the ammunition drum unless the drum is discarded off the aircraft when it is empty.

    In that case, the weight per round for the MG FF is 202 g instead of 338 g.

    However, that will make all of your calculations more complicated as not every fighter weapon ejected spent links and cartridges. You'll have to find out for every specific installation you're looking at.

    Regards,

    Henning (HoHun)
     
  16. Ivan1GFP

    Ivan1GFP Member

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    Hello HoHun,

    Actually the calculations get even more complicated than that. If a bomber's gun station doesn't discard spent cartridge cases, you only lose the weight of the bullet and powder! I'll worry about that when it becomes an issue. At the moment, the ones I am working on don't have that issue.

    - Ivan.
     
  17. Ivan1GFP

    Ivan1GFP Member

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    Hello Folks,

    A couple weeks ago, I went to a local gun show and found a dealer with a LOT of .50 Cal MG links. I didn't need the full 30 pound box full of links, so I convinced him to sell me just a few for $1. I told him I only needed about a dozen or so and that I wanted to weigh them to calculate aircraft weights. I am entirely convinced that he thought I was crazy (which I probably am).

    For those that don't already know, there are at least three kinds of links used in disintegrating link belts for the .50 cal MGs. The first two are the M2 and M9 which hold the cartridges around the shoulder. They look VERY similar with very slightly different contours in the area between the loops. They are used for the .50 cal M2 and M3 BMGs for WW2 and Korean era aircraft. The rounds must be pulled out of the belt from the back.

    The third kind of link is one that has a tab to index into the cartridge's extractor groove. These do NOT work in tbe BMG. The rounds are pushed through the belt FORWARD to be chambered. This makes for a gun with a more compact action since the cartridge doesn't have to have room to move back before being chambered. I believe this is the M13 link, but am not sure.

    The links I got from this gentleman were of the M9 type. They appear to have a Manganese Phosphate frosted finish. None of the nineteen I got have any noticeable rust or discoloration.

    The average weight of these 19 is 268.8737 grains. Minimum is 262.7 grains. Maximum is 276.3 grains. Now I just have to figure out whether the M9 link was from the proper time period, but in any case, from the drawings, they look nearly identical. If anyone has a specification sheet for the M9 links, please post the link. (Pun intended!)

    Hope this helps someone out there.
    - Ivan.
     
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