MIG vs SABRE

[Altea]

Bomb racks and rocket rails weren't even fitted to the Mig !5 until the Mig 15 bis, (2nd version) it wasn't designed for frontal aviation, it was designed as a bomber interceptor.

No, it' wasnt. This is an old legend peddled from ignorant western so called "experts"*. Just look at soviet official specifications for the plane, they are no more secret and were published many times before in specialised litterature (cf Gordon and Komissarov). If you don't have any recent book about the plane, look even in wiki (russian) and use translator.

МиÐ"-15 â€" Ð'икипедия

Just four your information, the MiG-15 was intended from the mainstream (technical request) to carry 2 * 50 or 100kg bombs. So threre were fasteners underwings to accept bomb lauchers. Now was it fitted or not, is another problem...

And for more free information, rockets were not main soviet weapons since mid-1943 for ground attacks, but canons for light tanks and AFV's, and PTAB's for medium and heavy tanks...

Regards

* But general cliche/prejudice it was a long time ago considered taht the MiG-15 was created as a B-29 interceptor. Not from everyone of course, Bill Gunston for instance estimated with reason that MiG-9 was already perfectly fulfilling the job.

 

[tyrodtom]

Ignorant I may be, but I see nothing in the link you posted that disagreed with what I posted . It states the Mig 15 was designed to intercept the B29, ( was even a single B29 ever shot down by a Mig 9 ?) It also states the hardpoints weren't adopted to carry rockets or bombs until the Mig15 bis in 1950. The origional hardpoints were for drop tanks.

And only being able to carry 2 250 kg bombs would make it a very weak at ground support, even in the era.

 

[FLYBOYJ]

That is true but in the time it takes a Mig to shoot a few rounds, the F-86 had fired a bunch. At close range with its high probability of strikes (80%?), a one second burp (which the Mig-15 would also require) from an F-86 (100 rounds striking) has a big chance of of ripping apart a Mig-15.

All very true but it would depend where and when the rounds would strike. Compare the -86 to a shot gun with smaller shot and the MiG to a magnum. Many MiGs withstood the peppering of the .50 rounds just to fly away with fuel and hydraulic lines shot away. I think that would explain the "smoking" of the MiG-15 as reported by UN pilots.

No, it' wasnt. This is an old legend peddled from ignorant western so called "experts"*. Just look at soviet official specifications for the plane, they are no more secret and were published many times before in specialised litterature (cf Gordon and Komissarov). If you don't have any recent book about the plane, look even in wiki (russian) and use translator.

МиÐ"-15 â€" Ð'икипедия

Just four your information, the MiG-15 was intended from the mainstream (technical request) to carry 2 * 50 or 100kg bombs. So threre were fasteners underwings to accept bomb lauchers. Now was it fitted or not, is another problem...

And for more free information, rockets were not main soviet weapons since mid-1943 for ground attacks, but canons for light tanks and AFV's, and PTAB's for medium and heavy tanks...

Regards

* But general cliche/prejudice it was a long time ago considered taht the MiG-15 was created as a B-29 interceptor. Not from everyone of course, Bill Gunston for instance estimated with reason that MiG-9 was already perfectly fulfilling the job.

Agree on all points not sure about the MiG-9 though.

 

[davparlr]

All very true but it would depend where and when the rounds would strike. Compare the -86 to a shot gun with smaller shot and the MiG to a magnum. Many MiGs withstood the peppering of the .50 rounds just to fly away with fuel and hydraulic lines shot away. I think that would explain the "smoking" of the MiG-15 as reported by UN pilots.

At close range (a variable) dispersion would be small and 100 rounds of close grouped 50 cals would cut off a wing, destroy an engine, tear off a tail, or destroy the cockpit. I said there was a great probability of destroying the Mig not 100%. This would not be a peppering.

 

[davparlr]

I study aviation and aerodynamics, and i like the Sabre. I also think it would win because the tail of the MIG 15 would cause a lot of drag, and the F-86's tail will cause less drag. The Sabre's elevators didn't work as much as the MIG 15, which is why the MIG 15 has a better rate of climb, but the MIG's engine is to strong, so it would would always lose wings and stuff and go into a stall with a lot of yaw, putting the aircraft into a spin. Also, the Sabre was used for a longer amount of time in more countries, and the last country to use it, Bolivia, didn't retire it until 1994 or 96. (meaning it was a safe, reliable aircraft)

I think the F-86 is clearly a superior aerodynamic design and was capable of transonic and supersonic (which it did in power dives) flight which the MIG was incapable of doing. With advent of the E and F with its hydraulic flight controls, flying horizontal stabilizer (stabilator), and the already used radar ranging gunsight and g-suit, the F-86 was the first, or certainly one of the first, truly modern jet fighters.

Primary use of the elevator/stabilator in climb, other than basic stability, is to set the climb angle of attack. The climb performance of the MIG is probably mostly due to its significantly better power to weight ratio, almost 40%, and possibly the wing profile. Wing loading is similar.

I think the MIG-15 was around for quite a while also.

 

[Altea]

Hello

Altea, your statement that heavier projectiles maintain their velocity better than lighter projectiles .

You mean that in my sentence in general case heavy bullets mantain their speed (cinetic energy) much better than fast lighter ones is not necessarily true..?
There are such polite men here, that moderators will be soon out of job?!

The reality of things make the world of physics much more complicated than the scholar "cinematic of point" formulas.

The FAMAS 5.56 bullet had the better BC shape than french 155mm shell. But it best range does not exceed 3,2 km with 925 m/s initial speed.
The canon reaches 17.5 km with less than 650 m/s initial speed.

A projectile that has a better ballistic coefficient maintains it's velocity better. The ballistic coefficient is heavily influenced by the shape of the bullet. A short, fat but heavy bullet will generally not have as good a BC as a long slim lighter bullet.The 50 BMG bullet had a very high BC and probably higher than the 23MM or 37 MM projectile.

This is true, but i don't think that your "heavily influence" will play in more than 10% between soviet and american shells/bullets BC. They are not just "sparrows" and "balls" after all.

The 50 BMG probably started off with a higher muzzle velocity and maintained that velocity much better than the Soviet projectiles.

Considering Bernouilli formulas (we're in an aviation forum after all):
Drag = KS(rhô)mV²
We can see with ease that a 50% (1.5) higher speed (2900ft/s to 2200) will lead to 2.25 higher drag on Browning shell. That means a much bigger speed dectrease rate (gradient). And this, during the whole differential equation of trajectory.
Moreover the law of conservation of the quantity of movement (dynamic of corps) will play in favor of the shell with the higher value.

At very high altitudes because of less drag, the 50 BMG bullet would be a very long range weapon.

It will equally play for the soviet canons too.

I have read of lethal hits at 700 yards on Migs.

What would be the curvature at that distance? (distance in m) And discrepancy of the weapon. (aera in m²)
Lethal you say?
The MiG-15 bis SN° 2915328 of major Karataev from the 532th IAP recieved 119 incoming bullets on sept 52 the 16th (more than 250 holes), 24 of them in the engine. Within 16 days, the plane was repeared and airworthy!

The max records noticed up to 204 12.7 mm shells hits, with plane coming back on the airfield...

Regards

 

[Altea]

Ignorant I may be,

When did i say that?

but I see nothing in the link you posted that disagreed with what I posted . It states the Mig 15 was designed to intercept the B29

,
Can you show us, where this link speaks about B-29?

It also states the hardpoints weren't adopted to carry rockets or bombs until the Mig15 bis in 1950. The origional hardpoints were for drop tanks.

And so for this points, where is the line, paragraph?

 

[davparlr]

Hello

What would be the curvature at that distance? (distance in m) And discrepancy of the weapon. (aera in m²)
Lethal you say?
The MiG-15 bis SN° 2915328 of major Karataev from the 532th IAP recieved 119 incoming bullets on sept 52 the 16th (more than 250 holes), 24 of them in the engine. Within 16 days, the plane was repeared and airworthy!

The max records noticed up to 204 12.7 mm shells hits, with plane coming back on the airfield...

Regards

If true, obviously struck at the limit of lethality of the rounds, 700 yards, 1000, more? Where is the testimony of the MIGs that fell to only a handful of hits? Oh yeah, they are smoking holes in the ground. Comments like this mean, statistically, nothing.

 

[tyrodtom]

When did i say that?

,
Can you show us, where this link speaks about B-29?
Under design and developement 9th paragraph


And so for this points, where is the line, paragraph?

Under design and developement paragraph 7

Let's face it, if the Mig 15 was origionally designed as a aircraft for frontal aviation, instead of as a interceptor, it fell sadly short of the standards of other aircraft of the same era. It could only carry a total bomb load of 1100 lbs ( 500 kg) the F84 could carry 4400 lbs, the A1E could carry 12.000 lbs, even the lowly T28 could carry 2000 lbs.
Then with the bombs taking the place of where the drop tanks normally would be it's combat radius would be short.

 

[Altea]

No i still can't see you're talking about...
I doubt we're quoting the same site. Can you give a link the site you use?

Under design and developement paragraph 7

In russian wiki

-paragraph 7 is Лицензионное производство : Production under licence
-paragraph 9 Боевое применение: Combat use, or Operational history


The specifications are in paragraph (or part) 2: Frontal fighter* is clearly written over the specifications notebook, but not mentionned in wiki. Since this notion is quite fuzzy, VVS precised the missions.

Назначением самолёта, согласно документу с требованиями, утвержденному А. К. Вершининым являлось:

-Ведение активного воздушного боя с истребителями и бомбардировщиками противника;
-Отражение налётов авиации противника;
-Действия по наземным целям;
-Выполнение задач разведки и контроля боевых действий.

I will tranlate later (you can do it by yourself in the meantime), but no mention about any B-29 or heavy bomber as you can see

* Sometimes we can find "general superiority fighter" in soviet docs. It means about the same things in "soviet military" late 40ies language.

 

[tyrodtom]

I used the english translator of the site you provided. But when I compare the english translation site with the russion site I can see they have a completely diiferent layout.
But in that translation, it mentions both that the Mig 15 was designed to intercept the B29, and other bombers , left unsaid was the B50 and B36, but taken for granted. Also mentioned is that the hardpoints for drop tanks weren't modified for ordance until the second version Mig 15 bis, which went operational in early 1950. Three years after the first Mig 15 prototype flew, and 2 years after the first production models flew.

I realize frontal aviation doesn't mean just ground support, but was high altitude bomber interception also one of it's missions ?

 

[renrich]

Altea, from ballistic tables online from the US Army, the 20 mm projectile has a BC of around .413 and a weight of around 2000 grains.
The 50 BMG has a BC ranging from .62 to 1.0 and the weight of around 700 grains.
According to Dean, "America's Hundred Thousand" WW2 50 BMGs had a MV of around 2800 FPS and the 20MM had a MV of around 2900 FPS.
Obviously the ballistic properties of the ammo in the Mig 15s and F86s are going to vary a little from the figures in Dean and the Army figures in 1946 but for practical purposes they will be roughly the same.
Following is an example from a Hornady Handbook of reloading. I used to do a lot of it:
45 caliber, 500 grain bullet, BC is .297, Muzzle velocity of 2600 FPS-at 300 yards the velocity is down to 1780 FPS
7 MM , 175 grain bullet, BC is .447, muzzle velocity is 2600 FPS-at 300 yards the velocity is down to 2030 FPS
As you can see, a much heavier bullet, with a worse BC launched at the same MV as the smaller lighter bullet with a better BC loses it's velocity faster and therefore will have a less flat trajectory.
Those are pretty similar comparisons to the Russian cannon shells and the 50 BMGs.

 

[Altea]

Hello,
First i answered too fast, and mismatched the BC with Cd.
I like planes , not guns...

First i will correct my sentences

The FAMAS 5.56 bullet had the better Cd (not BC) shape than french 155mm shell. But it best range does not exceed 3,2 km with 925 m/s initial speed.
The canon reaches 17.5 km with less than 650 m/s initial speed.

then

This is true, but i don't think that your "heavily influence" will play in more than 10% between soviet and american shells/bullets Cd not BC. They are not just "sparrows" and "balls" after all.


The Bernouill formula Drag = KS(rhô)mV² stays in force with K ~ Cd
Cd is not full constant with Reynolds number variation.

Altea, from ballistic tables online from the US Army, the 20 mm projectile has a BC of around .413 and a weight of around 2000 grains.
The 50 BMG has a BC ranging from .62 to 1.0 and the weight of around 700 grains.
According to Dean, "America's Hundred Thousand" WW2 50 BMGs had a MV of around 2800 FPS and the 20MM had a MV of around 2900 FPS. Obviously the ballistic properties of the ammo in the Mig 15s and F86s are going to vary a little from the figures in Dean and the Army figures in 1946 but for practical purposes they will be roughly the same.

I don't know the kind of desease was suffering the american 20 mm to have such a low BC, but obviously it's not transmissible to soviet, french or german ones.
I mean 20 mm shells had better working heights than standard NATO 12,7 mm bullet.

About BC, if we take formulas

BC = M/Cd A ....means that for the same bullet shape, if you increase the caliber by 2, you will increase the weight M by 8, and the A section aera only by 4. It means passing to the 25.4 from 12.7 caliber all things being equal, will increase your BC by 2 factor.

I will add from myself there will be also a little Cd decrease, due to higher Reynolds number.

I insist that Cd wouldn't change a lot, between soviet 23 x 115, and 12.7 x 90 mm amnution (from about 1 to 5 or 1 to 7 d/l relationship, differences are of logarithmic kind)

So keeping about the same Cd as i previously said

We will obtain from the 12.7 to the 23 mm the the evolution:

BC = 40.3 to 200 grams (4.96) / Cd x 12.7 to 23 (1.81)

In fact a 2.74 BC increase for the soviet shell.


From 12.7 to 37 mm we will have a

BC = 40.3 (622 grains) to 760 (18.85) / Cd x 12.7 to 37 (2.91)

So à 6.47 BC increase!

This is no the 100% truth, just a general tendency...
And don't forget air resistance formulas, with 2900/2200 = 1.32 more speed; the american bullet will have 1.73 more air resistance so a 1.73 higher initial speed decrease rate...

Those are pretty similar comparisons to the Russian cannon shells and the 50 BMGs.

I don't think so, we need more precise numbers.
Ask for yourself why US 90 mm canon could fire on 10 km ceiling, and the 0.5 browning less than ~ 2 km (In practical less than 1 - 1.5 km in vertical for accuracy problems in AA variant in french army).

 

[renrich]

Nothing wrong with the US 20 mms. Perhaps you would care to post the BCs of the German. Russian, etc, comparable 20 mm rounds. I have some pictures of German AC cannon rounds in a book and they certainly do not look anymore drag resistant than US rounds. I will not contest your math because I am no math expert. All I know about ballistics is from handloading for 30 years or so. How about coming up with precise numbers to prove your point? If you can, from a reliable source, show me that the Russian 23 MM rounds in the Mig 15 or the 37 MM rounds have a better BC than the 50 BMGs in the F86, I will gladly say, Calf Rope! In the meantime I will go with the Hornaday Handbook.

Did a little reading online to refresh my memory about external ballistics. Google external ballistics and there are some useful articles.
Two factors which heavily influence the BC are sectional density and form factor. Sectional density is the relationship of the diameter versus the length of the projectile. A long slim projectile has better SD than a short fat one. Form factor is the shape of the projectile, ( blunt nose, flat nose, pointed nose, boat tail, etc.) A projectile with a high SD along with a high FF will have a higher BC than vice versa. A high SD also means the projectile will have better penetration of the target. Of course that penetration is also influenced by the FF.

The factors which play a role in the comparison of aircraft gun ammunition are that as the diameter of the projectile increases, in order to have the same SD, the length of the projectile must go up which in turn makes the weight go up. In order to maintain the same velocity, if the weight goes up, then more propellant is needed and the barrel needs to be longer which means the gun gains weight and the recoil is higher. Those factors rapidly become an issue with aircraft guns. The reason a US 20 mm shell does not have the BC of a 50 BMG bullet is that the SD of the 20MM is not as high and the FF is slightly lower, probably because of the shape of the nose. The 20 mm could be made to have as high a SD but the projectile would then weigh too much to maintain it's velocity.

The simple answer to why a 90 mm shell has greater range than a 50 BMG is that it has a better BC, a result mainly of a higher SD. Same reason a 16 inch naval shell has more range than a 90 mm AA shell.

An example of how the above factors can influence AC guns is the A6M. It had two 20 MMs in the wings. I believe they were copies of the Oerlikon. To save weight, they had short barrels and the gun receivers were as light as possible. The MVs were down around 2000 FPS, to reduce recoil and weight and the trajectory of the shells was rainbow like. Consequently the 50 BMGs in the US AC outranged effectively the 20 MMs of the Zekes substantially.