DCS Bf 109K-4

[julian265]

At what ranges did the MK 108 achieve a theoretical 1.5 mil, and under what conditions?

http://en.wikipedia.org/wiki/Angular_mil#Metric_Mil-dot_formula

 

Quoting mils without a distance doesn't mean much... Unless you are under the impression that accuracy decreases linearly with distance :lol:

[Kurfürst]

Yes, provided that the said accuracy would change much with maximal distances up to and around 1000 m.. or that flight simulations would bother with calculations for each round, based on complex ballistic tables detailing data for 100 meter intervals, including corrections for humidity, temperature etc. :doh:

Edited November 13, 2014 by Kurfürst

[OutOnTheOP]

The GAU 8 is not really comparable to the MK 108, as its a radically different setup (multiple barrels, extremely powerful round and obscene rate of fire) which greatly contributes to that its accuracy (dispersion) is much worse at 5+ mils, as given by the report. Of course the GAU just literally obliterates any target with the sheer amount of rounds fired - it very much works like a huge shotgun firing #000 DU shots.

 

Now, that's just ignorant. The GAU-8 is, and was designed explicitly as, one of the more accurate aerial guns out there. There are HUNTING RIFLES out there that barely hold 5 mils of accuracy beyond 700-800 meters.

[Kurfürst]

The GAU 8 may be well one of the most accurate large caliber Gatling guns, and as close to perfect for the job it was meant to do, but its pointless to compare it to the others, be it small caliber, single shot bolt action rifles or 120mm APFSDS tank guns. You build a Gatling for Rate of Fire, not for accuracy.

 

In any case, the GAU 8 has nothing to do with the K-4.

[Pilum]

Concerning the accuracy of engine mounted cannon, the Ta 152 flight manual (Flugzeughadbuch Ta 152 H-0/H-1 Schusswaffenanlage teil 8A) page 37, states the following allowable dispersion for the Mk108 in ground testing:

 

"100% of the rounds for an 11 round burst shall hit within H=35 cm and B=30 cm at 100 m range." (My translation)

 

This is pretty darn accurate. In fact it is even more accurate than for the wing mounted Mk 151/20 which had an allowable dispersion of H=60 cm and B=100 cm for a 22 round burst. Also, remember this is the 100% area and since it make sense to assume a normal distribution within the 30x35 cm area, the pattern is pretty tight.

 

So the engine mounted Mk108 is in fact more accurate than the Mk151/20 we have in the Dora now. Granted this is the Ta152, not the Me109K but I don't think the results would be much different: The key issue is most likely the engine mount: You have a huge mass to which the cannon is mounted which results in less movement than for other types of installation like in wings.

 

I posted about the Mk108 accuracy earlier in this thread to preclude that DCS follows in the same sorry path as previous sims like EAW and IL2 and model the firing Mk108 as jumping around and spraying shells all over the place .....

 

Will be very interesting to see if DCS breaks traditions here and models the Mk108 as the instrument of precision that it apparently was or if we will see the return of the blunderbuss :)

[Friedrich-4B]

Concerning the accuracy of engine mounted cannon, the Ta 152 flight manual (Flugzeughadbuch Ta 152 H-0/H-1 Schusswaffenanlage teil 8A) page 37, states the following allowable dispersion for the Mk108 in ground testing:

 

"100% of the rounds for an 11 round burst shall hit within H=35 cm and B=30 cm at 100 m range." (My translation)

 

This is pretty darn accurate. In fact it is even more accurate than for the wing mounted Mk 151/20 which had an allowable dispersion of H=60 cm and B=100 cm for a 22 round burst. Also, remember this is the 100% area and since it make sense to assume a normal distribution within the 30x35 cm area, the pattern is pretty tight.

 

So the engine mounted Mk108 is in fact more accurate than the Mk151/20 we have in the Dora now. Granted this is the Ta152, not the Me109K but I don't think the results would be much different: The key issue is most likely the engine mount: You have a huge mass to which the cannon is mounted which results in less movement than for other types of installation like in wings.

 

:thumbup: Thanks for that.

[OutOnTheOP]

allowable dispersion for the Mk108 in ground testing:

 

"100% of the rounds for an 11 round burst shall hit within H=35 cm and B=30 cm at 100 m range." (My translation)

 

This is pretty darn accurate. In fact it is even more accurate than for the wing mounted Mk 151/20 which had an allowable dispersion of H=60 cm and B=100 cm for a 22 round burst.

 

That's only 3.5 mils at 100 meters for the Mk108... which, incidentally, probably opens up to well beyond 5 mils at 1000 meters, given that they would go transonic well before then.

 

The MG151/20 wing mount is a whopping 10 mils at a mere 100 meters, if your data is correct.

 

Huh, guess that means my comment about the GAU-8 being more accuratate was... oh, man, what's the word... the antonym of "wrong"...? Gee, it's at the tip of my tongue!

[Kurfürst]

That's only 3.5 mils at 100 meters for the Mk108... which, incidentally, probably opens up to well beyond 5 mils at 1000 meters, given that they would go transonic well before then.

 

The MG151/20 wing mount is a whopping 10 mils at a mere 100 meters, if your data is correct.

 

Huh, guess that means my comment about the GAU-8 being more accuratate was... oh, man, what's the word... the antonym of "wrong"...? Gee, it's at the tip of my tongue!

 

Gauss. You are looking for Gauss.

[Friedrich-4B]

That's only 3.5 mils at 100 meters for the Mk108... which, incidentally, probably opens up to well beyond 5 mils at 1000 meters, given that they would go transonic well before then.

 

The MG151/20 wing mount is a whopping 10 mils at a mere 100 meters, if your data is correct.

 

Not forgetting that Pilum's data is gathered from ground based tests, where the ranges were known and there were no in-flight variables to contend with. The results for the GAU-8 were gathered from air-ground attacks under combat conditions.

[MiloMorai]

When were the inflight malfunctions of the MK108 fixed, if they ever were?

[Altflieger]

When were the inflight malfunctions of the MK108 fixed, if they ever were?

 

Don't know Milo, but I'm sure you're desperate to tell us....Sources please.

[snuffles]

That's only 3.5 mils at 100 meters for the Mk108... which, incidentally, probably opens up to well beyond 5 mils at 1000 meters, given that they would go transonic well before then.

 

You're talking mils, which is a measure of angular variation correct? In that case (linearly) your deviation (as a guide) would still be 3.5mils measured from the POF to the POA, no matter the distance past 100m. Taking ballistics into consideration, the MPI may vary but the spread angle measured would remain consistent wouldn't it? Only the MPI area would change, by factor similar or equal to that of the variation in distance?

[Kurfürst]

Also one of the rare occasions I actually agree with Holz.

 

this might prove interesting.

 

http://forums.eagle.ru/attachment.php?attachmentid=107361&stc=1&d=1415955237

Edited November 14, 2014 by Kurfürst
added dispersion doc

[sobek]

In that case (linearly) your deviation (as a guide) would still be 3.5mils measured from the POF to the POA, no matter the distance past 100m.

 

Linearity is a concept seldom encountered in physics.

[sobek]

Let's try to go five posts without an insult. Something i'd like to see this motley crew manage once in my life.

[snuffles]

Linearity is a concept seldom encountered in physics.

This is true - so without verified ballistics data readily at hand we can only make educated guesses. meh!

[Kurfürst]

Some additional gun dispersion data, via Olivier Lefebrve / AAW:

Here are the results of a lenghty research into dispersion data, which is quite hard to come by...

The data is based on 100% diameter dispersion with 1 mil = 1/1000th of rad, the kind of mount is precised next to the weapon. 75% dispersion diameter is supposed to be half the 100% diameter which seems quite true for most weapons, this value is provided when quoted in the source (M2 data for instance).

 

We can clearly see the impact of the wing mounting compared to engine mounting, the later seems to have absorbed recoil and vibration much better... indeed dispersion is at least 2 times greater with wing mounted weapons.

Engine mount are the most efficient but nose mounting or cowling mounting does not provide the same amount of precision the mount being much more prone to vibration it seems.

 

Note that US data on the M2 is confusing since the reference data comes from a P-38 nose mounted M2, but the US manuals use the same dispersion data for wing mounted weapons. Either the P-38 mounts are really up to no good or the manuals make a wrong assumption when it comes to wing dispersion. I tend to believe the later, i think the wing mounted M2 would have had a dispersion of at least 12mils and probably more.

 

If you quote this data on other sites/bbs please precise the source being AAW. TIA

H means Height (or max dispersion diameter) as i previously used vertical and lateral dispersion values.

 

D means distance.

 

Units are metric.

 

German Weapons

-----------------------

MG-17 Cowling mounted (Bf 109F-2 / Bf 109F-1 actual tests)

H = 0.60 / 0.8 m

D = 100 m

R/D = 60/10000 80/10000

= 6 mils / 8 mils

 

MG-131 Cowling mounted (Fw 190A - theorical max)

H = 1m

D = 100m

H/D = 100/10000

= 10 mils

 

MG-151/15 Engine mounted (Bf 109F-2 actual test)

H = 0,35 m

D = 100 m

H/D = 35/10000

= 3.5 mils

 

MG-FF Engine mounted (Bf 109F-1 actual test)

H = 0,2 m

D = 100m

H/D = 20/10000

= 2 mils (very tight patern)

 

MG-FF Wing mounted (Bf 109E-3 actual test)

H = 0,35 m

D = 100m

H/D = 35/10000

= 3.5 mils

 

MG 151/20 Engine mounted (Bf 109G-6 - theorical max)

H = 0.3m

D = 100m

H/D = 30/10000

= 3 mils

 

MG 151/20 Wing mounted - inner (Fw 190A - theorical max)

H = 0.7m

D = 100m

H/D = 70/10000

= 7 mils

 

MG 151/20 Wing mounted - outer (Fw 190A - theorical max)

H = 0.8m

D = 100m

H/D = 80/10000

= 8 mils

 

MK 108 Engine mounted (Ta 152 - therorical max)

H = 0.35

D = 100m

H/D = 35/10000

= 3.5 mils

 

Allied Weapons

------------------

M2 Nose mounted P-38 (USAAF 1944 Gunnery manual)

H = 1.88 m

D = 229 m

H/D = 188/22900

= 8.2 mils (75% = 4.1 mils)

 

Hispano 20mm Nose mounted P-38 (USAAF 1944 Gunnery manual)

3 mils 75%

6 mils 100% assumed

[Friedrich-4B]

This is true - so without verified ballistics data readily at hand we can only make educated guesses. meh!

 

The attachment should help (also included is data on munitions colours etc)

 

From

 

Edited November 15, 2014 by Friedrich-4/B

[snowsniper]

hi,

 

Someone knows if there is somewhere a downloadable 109k skin template .... to be ready on "release" Day. ;-)

 

:music_whistling:

[Maler]

hi,

 

Someone knows if there is somewhere a downloadable 109k skin template .... to be ready on "release" Day. ;-)

 

:music_whistling:

 

I think the day of release or a little earlier will appear here

http://forums.eagle.ru/forumdisplay.php?f=359

[fastfreddie]

Loved to see a manual and takeoff/startup tutorial!

[9.JG27 DavidRed]

didnt the k4 have slats??on eds model i cant spot any...

[Maler]

didnt the k4 have slats??...

yes have slats

[9.JG27 DavidRed]

^^yeah i was assuming that, but i watched now i think every single screenshot available, and not on one there is a sign of them...thats why i was asking

[JST]

You can see them on the screenshots, you just have to look really closely. For some reason they're not open on the ground, though.