VVS Vs. RAF

delcyros said:

But back to the turning datas. Soren, you still failed to provide own datas about it.

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Own data's ? Have you read Hans Werner Lerche's (Luftwaffe test-pilot) book ? He flew virtually all captured Allied aircraft and most German types, including experimental models.

The slats are described but in howfar do they work? We need datas to compare them.

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What do you mean the slats arent fully described ? I've already presented you all the facts about how the automatic slats work. What more do you want ? Their piece by piece description ?

To put it simple; The 'automatic slats' work at all speeds, and their deployment depends on the wings AoA.

200 mp/h are not that bad for a Fw-190 to turn sustainably.

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Come on ! your quoting the 109E to have just as bad a turn-rate as the Fw-190A, which is just not true !

The 190's turn-rate numbers are very suspicious aswell.

Actually I have these numbers from a Rechlin test (Fw-190A). If there is something wrong with them I would like to know.

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So where did you get the 109 numbers from ? Cause they certainly don't compare to the ones I've seen before !

Roll data's cannot be calculated exactly by comparing pure data's. We need statistics about different speeds and altitudes for them.

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No but accurate assumptions can be made from them.

No, I haven´t read Lercher´s book (yet). Does he provide more datas or just subjective experiences of the turning datas?
I don´t want to know in detail about the slats, it´s airflow principle is known to me. I just want to know if there are any datas to confirm this?
E.g. a comparison between a Bf-109E with working slats and with fixed slats. There should be differences in the turning performances. If you have datas, I suggest to post them.
The Bf-109E would always turn inside the Fw-190. If you check the turning datas you will find this confirmed. While the turnrate is close to each other (keep in mind that in this particular test the slats of the Bf-109E are not fully deployed, thus are reducing the Bf-109E´s performance a bit), the turning diameter of the Fw-190A-4 is much larger thanks to it´s higher speed at turning. The difference is quite big.
If you have turning datas (you said you have seen other datas), please post them.

No, I haven´t read Lercher´s book (yet). Does he provide more datas or just subjective experiences of the turning datas?

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Yes he does, and the Fw-190A's turnrate lies at around 25-26 sec for a full 360 degree turn without loss of height !

I don´t want to know in detail about the slats, it´s airflow principle is known to me. I just want to know if there are any datas to confirm this?

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Wait a minute, you just said you knew their airflow principle, but then you say you need data to confirm this ? Its bloody simple aerodynamics buddy !

They work the way I (And the illustration) explained to you, but since you seem to have missed this, I will explain it again:

Without slats the wing would stall at certain AoA, the airflow turning turbulent at the same moment with sudden enormous increase in drag. With slats the airflow stays non-turbulent for some extra amount of AoA, and there will not be any "stepped" increase in drag when the slats deploy, only at the point where even the slats cannot prevent the wing entering a stall.

You can also see this confirmed on the illustration that I gave you, as it is clearly stated that seperation is delayed. And it is also clearly stated that the "stall-angle" of the wing is increased.

E.g. a comparison between a Bf-109E with working slats and with fixed slats. There should be differences in the turning performances. If you have datas, I suggest to post them.

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Del, what are you talking about ? No 109 had fixed slats, they were all fitted with "Automatic slats". The German Me163 Komett had fixed slats, and yes they increased drag, although that didnt matter much on a rocket propelled a/c. Bottom line is (As explained above) the "Automatic-slats" DONT give any increase in drag at all !

I can tell you this aswell, the auto-deployment of the slats was subject to extensive testing prior to WW2, and was found to be beneficial in all situations, and they were therefore installed on the 109 permanently. If they in anyway were unessential or degraded A/C maneuverability they would have been removed as they were expensive and complicated to make, but they weren't removed.

The Bf-109E would always turn inside the Fw-190.

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Exactly, and every mock-fight between them proved this, as it is quoted time and again that the 109 "Easely" outturns the 190.

If you check the turning data's you will find this confirmed. While the turnrate is close to each other (keep in mind that in this particular test the slats of the Bf-109E are not fully deployed, thus are reducing the Bf-109E´s performance a bit), the turning diameter of the Fw-190A-4 is much larger thanks to it´s higher speed at turning. The difference is quite big.

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As I've already said the Fw-190A's turn-rate would normally lie around 25-26 sec for a full 360 degree turn without loss of height.

Now where did you get those 109 numbers from ?

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More 109 pilot quotes:

Herbert Kaiser, German fighter ace. 68 victories:
"Personally, I met RAF over Dunkirk. During this battle not a single Spitfire or Hurricane turned tighter than my plane. In the desert there were only a few Spitfires, and we were afraid of those because of their reputation from the Battle of Britain. But after we shot a couple of them down, our confusion was gone."

Helmut Lipfert, German fighter ace. 203 victories:
"I cast a quik glance at the machine and then climbed up after the other enemy aircraft. Damn, he could turn! Finally I was sitting behind him. I turned so tightly that condensation trails formed behind both wingtips and my Me shuddered on the verge of a stall more than once. Fortunately, the 109 turned extremely well.
The whole air battle took place at a very low altitude. I sat behind the Russian like a shadow, and now and then I succeeded in hitting him.......
He (Russian pilot) turned sharply, leaving a heavy vapor trail, and dove away towards the northeast.......... I cut him off and closed in at high speed. My airspeed indicator was showing more than 750 km/h.
I opened fire rather too soon, but he didn't change direction, instead he put his nose down briefly so that I was suddenly a level higher than he was. I put my nose down as well, but as I was about to fire he pulled up again, and this time I ended up below him."

Could be that there is some miscommunication?
Slats: you (again and again and...) describe how they work. Ok. What I want to know is how far makes this a difference, in numbers (e.g. take a bf-109 with slats in working condition and those which are (arteficially) fixed and compare the turning datas: turning speed in sec., stall speed, turning diameter and so on. Of course there is no additional drag if the slats are n ot deployed, they disappear in the leading wing surface. But they produce beside of lift a specific amount of drag if they are deployed, and that´s what I want to know. I know that there have been tests with these automatic slats in bf-108 planes, but while the wing is almost the same, you cannot compare the bf-108 with the bf-109, there is lot of differences in the performances.
The sources for bf-109 E is the RAF comparison flight between Hurricane and bf-109E in 1940. You will find this document if you run www.lanpartywolrd.com/ww2/files and search for aircraft comparsison files. There is lot of datas (scanned original documents, but also manuals and lot of other stuff).For bf109F2 and Fw-190 A is the Rechlin test in oktober 1942 (see my first post to this problem).
25-26 sec. is quite high for a Fw-190A4. The A-8 comes close to this (24.5 sec at 218 mp/h after my sources) but the A-4? The Rechlin tests show me a differnet figure for it.

Could be that there is some miscommunication ?

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It certainly seems that way !

Slats: you (again and again and...) describe how they work. Ok. What I want to know is how far makes this a difference, in numbers (e.g. take a bf-109 with slats in working condition and those which are (arteficially) fixed and compare the turning datas: turning speed in sec., stall speed, turning diameter and so on.

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As I've said earlier, the slats (When deployed) provide about 45% extra lift to the wing. Now it should be easy for you to calculate the rest.

Of course there is no additional drag if the slats are n ot deployed, they disappear in the leading wing surface. But they produce beside of lift a specific amount of drag if they are deployed, and that´s what I want to know.

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I repeat: A wing without slats will stall at a certain AoA, the airflow turning turbulent at the same moment with a sudden enormous increase in drag. With slats the airflow stays non-turbulent for some extra amount of AoA, and there will not be any "stepped" increase in drag when the slats deploy, only at the point where even the slats cannot prevent the wing entering a stall.

A wing without slats will stall at a lower AoA, and therefore produce alot more drag (Earlier on) in banking maneuvers, than a wing equipped with slats. Which means that a fighter equipped with slats will lose energy at a slower rate in banking maneuvers, than a fighter without slats.

I tried to explain this to you many times, but you obviously missed it yet again.

I know that there have been tests with these automatic slats in bf-108 planes, but while the wing is almost the same, you cannot compare the bf-108 with the bf-109, there is lot of differences in the performances.

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Del, what are you now talking about ?

The slats were tested on the Bf-109 ! Your not seriously trying tell me that you actually believe that they would put Auto-slats on a Bf-109 without testing it first, now are you ?!

I was talking about tests with the 109 ! And on the 109 the slats were found beneficial in all situations, also by Willy himself ! That is why they were fitted permanently on the 109, and never removed. The auto-slats were highly expensive and complicated to manufacture, so if they in any way degraded A/C maneuverability or performance, they would've been instantly removed, but they weren't !

The sources for bf-109 E is the RAF comparison flight between Hurricane and bf-109E in 1940. You will find this document if you run www.lanpartywolrd.com/ww2/files and search for aircraft comparsison files.

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Which makes the rest of your data totally merit-less. You can't compare two totally different tests from different country's !

Furthermore RAF's tests with the 109 are useless, as they barely dared flying it. And I've explained before why.

Btw notice the site's description

25-26 sec. is quite high for a Fw-190A4. The A-8 comes close to this (24.5 sec at 218 mp/h after my sources) but the A-4? The Rechlin tests show me a differnet figure for it.

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The Fw-190A's turn rate lies at 25.5 - 26 sec.

May I make a request that you start a new thread on the effect of aerodynamic devices on the performance of aircraft in Combat. It truly could be interesting as a number of aircraft had devices to help.

This thread is about the VVS and the RAF. Not if the 109 slats made it turn inside almost anything else in the air.

that is a very good request i agree, whilst this is interesting it's off topic..........

and you're almost at 100 posts glider........

Certainly.
Back to the topic. Originally we did compared the Mig with the Spitfire V in 1941. As we have seen, both are comparable planes, each having advantages of it´s own at specific altitudes. Both planes are very comparable at low altitudes (at sea level, the Spit even have an advantage over the Mig´s performance), while at higher altitudes the Mig has the better performance. In my view, we can count the Mig as the better high altitude plane and this is going to be notable, since it´s going to disprove that the VVS could never field a plane in the high altitude field. Actually this is more important in this thread, since the RAF would more probably depend on high altitude sorties compared to the Luftwaffe.
Of course, there are better high altitude Spitfires possible, the Spitfire VI to name one, but the Mig´s does also have more advanced high altitude planes, none of them was produced in masses anyway.
But about what a timeframe are we talking? 1939, where the british declared war on the soviets, who -alongside with nazi Germany- atacked Poland? Or 1941? 1945? I think, the sooner you put the VVS on war, the bigger the advantage of it is. The later it goes the more would count the development of more advanced planes, finally the advent of the first (RAF) jet planes. What do you think?

Well, all the way up to 1942 the most numerous plane in VVS service was the I-16 wasn't it? It's hardly a formidable enemy, especially when it's shining point was turning and the Hurricane could out-turn it.

The Spitfire Mk.V would hardly be flying above 15,000 feet. The MiG-3 might have the advantage above 16,000 feet but RAF bombing normally took place below that altitude with any escort fighters being there also.
The MiG-3 would be trapped below it's optimal altitude in almost any combat occasion. It shows there was the foundation for a possible increase in high performance fighters but it isn't solid proof that the VVS could field anything on par with the Spitfire Mk.IX or XIV.

Performance is one thing but the problem with the Mig 3 is its lack of weapons. A Mig 3 would have a very hard time shooting down a British Medium/Heavy bomber with the 1xHMG and 2xLMG that it carried.
The standard 4xLMG rear turret on almost every British bomber from the Whitley on could be considered to outgun it.
I know that some were given an extra 2xHMG but any increase in weight on such a weight sensitive aircraft would significantly inpact its performance. For my money the Spit 5 is a better al round machine as its 2x20 and 4xLMG gives it sufficient punch to take on any VVS plane, fighter or bomber.

At 15.000 ft the Spit has considerably less performance than the Mig-3, even at 10.000 ft the Mig is faster (as it is in 5.000 ft.), and with four 0.50 and a single 0.33 the Mig has a comparable, if not better punch to a Spitfire Va and is less powerful than a Spit Vb. The recoil force of the two 20mm are wuite high for the Spitfire airframe (esspeccially if they are mounted in the mid of the wing), making prolonged aiming difficult. The Mig has all guns (except for two additional 0.50) mounted in the nose, this is an advantage. Without the disadvantage of a heavy recoil force.
The later Mig 3 did had some two 20 mm guns, which give them a better punch to bombers. But I don´t think that british bombers could stay on their own over soviet airspace. No bomber is probable to do so. Also as you can see, the Spitfire Vb has not much ammo to spent, indeed, much less than comparable VVS planes. The Spitfire Va or Vb would be in big trouble with hunting the Il-2, since they don´t have proper firepower and ammo. The Hurricane would have even bigger problems because they also lacked in speed. But in general, their armement is well suited do deal with VVS fighter.
As I posted earlier, the I-211 of 1942 was comparable, if not even better in performances than the Spitfire IX....draw. And it saw combat in mid 1942.
Bristol Blenheims, HP Hampdons and Wellingtons would have a hard time against numerous fighter attacks. If needed, the VVS would field more heavier guns (they had a good 37mm gun, excellent for downing bombers).
The I-16 was produced in heavy numbers most exclusively because the SU lost several aircraft factories and had to upbuild their lines completely new. The tooling for the I-16 was avaiable sooner. However, this goes more to the Blitzkrieg than anything else. The RAF equippment, unlike the Luftwaffe one, is not suited for such attacks. Had the RAF instead of the Luftwaffe attacked the VVS, there would be less probability to advance that fast, destroying that much planes on the ground and driving the VVS in such a desperate position as the Luftwaffe did. It´s simple, the RAF lacked dive bombers, numerical advantage of medium bombers and fighters as well as the proper tactics to do such attacks on a larger scale. With this in mind, the appearence of I-16 even in 1942 would be unproable in case the VVS attacked the SU.

The Spitfire Mk.V would rarely operate at 15,000 feet. The optimal altitude for the MiG-3 was above 16,000 feet, bombing was normally done at 15,000 feet. Rarely was it above that altitude although sometimes the B-17 did go to 30,000 feet!

The performance of the MiG-3 was greatly reduced with wing loaded 12.7mm HMGs. Your stats provide information for the MiG-3 without those guns. It doesn't have a comparable punch to eight .303cal or two 20mm and four .303cal.
The MiG-3 wouldn't have any recoil force anyway, it only had one 12.7mm and two .303cal without the wing loaded 12.7mm!

Explain accurately how the I-211 is as good as the Spitfire Mk.IX.

You're assuming the VVS could, in 1941-'42, affectively attach an effective 37mm armament to a high altitude fighter. It certainly wouldn't go in a MiG-3 because it'd shake the thing to pieces. In fact, it only went in the Yak-9U.

No, the reason for the large I-16 numbers was because their air force was made up of that before World War 2. They had thousands, all inferior aircraft to the Hurricane and Spitfire.
Hurricanes and Spitfires could do the same ground attack with bombs as the Ju-87. The RAF medium bombers such as the Wellington could provide the same support as He-111s and Ju-88s.

The Il-2 wasn't an invincible machine, Erich Hartmann downed many a Sturmovik in a Bf-109, which carried less or equal armament to any B,C or E wing Spitfire.

Delc. I only thought that the Mig 3 carried 1xHMG and 2xLMG. with two extra HMG bolted on under the wing as an extra. The weight of fire for the Mig 3 would be around 1.3KG per second in standard mode compared to around 3.5KG per second on the Spit, quite a difference. This excludes the considerably higher HE content of the 20mm shell which significantly increases the difference.
I am with PlanD in being quite certain that the Mig 3 with the extra two guns would have a lower performance as it was so weight sensitive. The figures would be interesting

Had the British attacked the VVS in 1942 the Hurricane 2C would have probably been used in GA and the Spit 5b as escort. No shortage of firepower there. Comparatively speaking few Spit 5a were made so I refer to 5b. Typhoons were entering service and would have been very difficult to counter. The RAF were not short of dive bombers, they basically didn't have any but any Hurrie 2C or Typhoon would have had a field day against the slow IL2 and were at least as effective in GA. I doubt if many German dive bombers shot down the IL2.

No one is saying a Wellington would have found the VVS a walk in the park but they would have stood a much better chance of surviving against a Mig than almost any other fighter in any other airforce of the time.

So to follow your summing up. We didn't have Dive bombers we had planes at least as good in GA and could defend themselves in air to air.
We didn't lack medium bombers and could have used Sterlings with a huge increase in bomb load to destroy the targets.
Our fighters were also capable of taking on the best that the Russians had.

Put the clock forward 6-9 months and we have Typhoons, Mossies, Halifax's and Lancasters comming of the production lines.

These are all but speculations.

Firsth of all Soviets and British would not be able to attack each other efectively by air. Distances were too big. British had long range strategic bombers which they did develop later in to formidable force. But they never had any fighter to escort them. War proved that bombers regardles hove good they are armed and protected can't operate without fighter escort unles taking heavy looses.

Brithis bombers operated during nihgt and even if they were efective in burning down German cities, this had little efect to German war efort. US daylight bombing was more efective but American themselfs declared afther post war analises that only small (15-30% if I remember) portion of bombs realy hit their targets.

Strategic bombing wasnt able to win war against Germany, there is no reason to beleive that it can do the job against USSR which much biger distances involved, les developed = les sensitive infrastructure, industry spreaded over large teritories + big resource and human reserves at Soviets hands.

And last thing, both airforces were developed to fight diferent enemy. If ever they would have faced each other, they would need to be developed and deployed diferently.

As for comparing planes against one to another. Dont forget that Soviet military philosophy was and (Russian) until now is diferent than that of western countries.
Soviets newer rellied on technical and technological quality as much as western countries. Quality was always evaluated in relation to production efeciency, easines of use, high reliability.
This philoshophy allowed them to use their advantages as much as possible while minimizing efect of their disadvantages. And they were higly succesful in this. Since winter 43 Germans practicaly did not have any chance to win war at Eastern front.

Arras you are right in that this is a theoretical exercise but that is for me part of the fun. For this to work you have to assume that the two sides can reach each other.

Yes, we are comparing air forces not distances. The RAF is a more well rounded air force than the VVS. The RAF was designed to fight at any length, height, day or night.

I won't start on the strategic bombing again, just go back and read the facts.

It´s just an interesting discussion.
The I-16 stayed, in fact, in production until 1942 because of the reasons, I listed. There are some thousends made earlier. It should be interesting that the I-16 could match with the Hurricane (altough I regard the Hurricane the better plane), esspeccially if the Hurricane shifts to the GA role. And the VVS had lots of I-16.
Another interesting point is the Wellington, it has a good range, allowing strikes deep into the european part of Russia (with a very small payload) at low speeds. Without escort.... -You know the rest.
The 37 mm gun would be fitted in either, a Yak-2, Yak-4, Yak-5 or Pe-2. These planes have been modified for the heavy fighter role (e.g. interceptor) late in 1941, but the VVS found that it could handle with He-111, Ju-87 and Do-215 with their regular forces, also.
The Spit V has a better armement than the Mig-3, agreed. I just pointed out that the Mig could be equipped better (including 20 mm guns in the Mig-3D), and keep in mind, it was by far not a fragile plane. Four 0.50 and a single 0.33 are a better armement than eight 0.33. Compare the parameters for the soviet 0.50 cal.gun rounds. Fragile belongs to the Yak-1 particularly. The Mig-3 had armor, fire resistent fuel tanks and a rugged airframe, much more durable than the average VVS plane. The Spitfire on the other hand is known for it´s weakness. I would rate them at about equal in this field. Hartmann killed many IL2 because he got close ups to them. And even than you need multiple 20 mm HE hits at vulnarable spots of the IL-2. This is well possible with nose mounted 20mm / 30mm guns but 0.33 and even 0.50 cal. guns are not suited for this task. Even the four wing mounted 20mm guns of a Hurricane would have problems thanks to convergance problems. At low altitude, the Hurricane is not much faster than the Il-2, the Typhoon would be much better in this task. The Spitfire has not enough ammo as we know, reducing it´s performance in this point.
Compare the I-211 (datas posted above)with the Spitfire IX, the I-211 beats the Spitfire in top speed, climb rate, ammo and acceleration while it is about equal in maneveurability and the I-211 has a radial engine, giving it an edge in durability. They are indeed comparable planes.
All in all, the Spitfire is not very well suited for the soviet climates, it´s far to prone to mechanicle problems. The Spitfire V send to Russia proved that. The Hurricane is much better in this.
A real problem for the RAF would be the disadvantage in numbers, I barely can see the RAF in the offensive role because the VVS had so much bombers and GA planes and fighters.

The I-16 was the most numerous fighter of the VVS in 1939-1942. If the war starts in 1939 then the RAF is fielding Spitfire Mk.I and Hurricane Mk.I against I-16s. The Hurricane is just superior to the I-16 in almost every aspect. The Spitfire even more so.

The Yaks would have to be getting up to the altitude of the RAF bombers. Remember that these bombers were heavier than Luftwaffe bombers and flew at a greater altitude.

The up-gunned MiG-3 with 12.7mm BK pod-guns under the wings gave the MiG-3 two 7.62mm ShKAS, one 12.7mm UBS and two 12.7mm BK.
I've read that many of the under-wing pods were removed when the units received the new MiG-3s because the extra 150kg drastically altered the flight characteristics, making them a much more clumsy aircraft.
The Spitfire Va was hardly produced, they were mostly Vbs with four Browing .303cal and two Hispano Mk.II 20mm. The Spitfire Vb armament was much more destructive and accurate than even the up-gunned MiG-3, especially during high G combat.

The Spitfire was not known for weakness, the liquid cooled Merlin was. The Spitfire had armour and self-sealing fuel tanks. The Spitfire V would normally be operating at 15,000 feet and below. The MiG-3 would be easy pickings below 16,000 feet.

The Spitfire Vb would have no problem with destroying Il-2s. The Hispano 20mm would cleanly rip a Il-2 to pieces. The Hurricane IIC would have an even easier time, getting in close eliminates the convergance problems. The Il-2 would be [and was] easy pickings for any fighters.

The Spitfire was not unable to cope with the Russian winter. The Soviet mechanics were not able to cope with the Spitfire, they were primitive. The Spitfire served in every theatre, with every Allied air force, you cannot honestly state that it wasn't capable of combat out of the ETO.
I know little of the Spitfire V action in the Soviet Union, even less of the Spitfire IX action but I do know this;

821st IAP, 8th Air Army, Sector between the rivers Molotchnaya and Mious, August-September 1943.
93 combats, 32 victories, 16 Spitfires lost.

3rd Squadron, 7th IAP of Black Sea Fleet.
10 Spits received in Summer 1943.
In May/August 1943 30 missions, mainly to escort sea convoys; 5 German bombers claimed.

57th GIAP, April/June 1944, Kuban.
46 combats, 31 victories, 11 Spits and 4 pilots lost.

The Spitfires sent to Russia were only withdrawn in some areas because the Luftwaffe was bringing the Bf-109G and Fw-190 to bare. The Russians enjoyed the Spitfire V in 1941 and early 1942. They were requesting the Spitfire IX because of it's high altitude performance, they needed it for their PVO to counter the Ju-86.
The Hurricane and Spitfire served with distinction in the Soviet Union. They both could handle the weather and they both could handle their opponent in their time span.

You should also notice the non com bat losses of Spitfires in Russia. During Nov-42-february 43 at Stalingrad (it must be noted that this timeframe was a really crude winter) the VVS lost several Spitfires due to mechanicle problems (weak undercarriege mostly) and 43 were put out of action by climates.
The Spitfire Vb clearly has the advantage in armement against the Mig-3. However, the Spitfire Vb also has a lower performance than the Va and much more recoil force. The recoil force is a problem, esspeccially if you try to make prolonged hits with the wing mounted guns. This force you to close up and this brings you in the hot zone of the defensive armement of the Il-2. Several Bf-109 have been destroyed by Il2 reargunners and the Spit is as vulnarable as the Bf-109. The ammo of the Spit Vb is also not enough to deal with more than one or two Il2. The british 20 mm gun is a good weapon, with better ap-capabilities than the german MG151/20, but you still need to get close enough to ensure that the rounds doesn´t glance off.
In 1939, howmany Spitfire and Hurricane could face the VVS?
I-16 against Hurricane, umm, the I-16 has an advantage roll rate, armement, durability and comes about equal in turnrate, speed and acceleration....
Some 300 Spitfire I and about 500 Hurricane against what? Alone 476 I-16 in spain, over 2000 fielded by the VVS in late 1939. The VVS had combat experience in Spain and Manchuria. It had a good medium bomber (SB-2) and lots of Chaikas for the GA-role. And not to forget the obsolete TB-3, a durable bomber with over 9000 lbs. payload, in quantities. No way, the RAF would be in a very defensive position in 1939.
But it is still very interesting, how would the RAF react? It is a hard job to deal with TB-3 or SB-2 while only having 0.303. But it is possible. I think the RAF would sooner shift to 20mm and the VVS would sooner put better planes into their airforces. The Yak-1 outclasses the Hurricane and Spitfire at low altitude (except for firepower and durability), the Mig-1 outclasses them at high atlitude (direct fuel injection! One of the prototypes made 404 mp/h but most planes have been flown without canopy, reducing it´s speed to "only" 370-380 mp/h, the handling of the Mig is sluggish, the Spitfire is much better).

Delc. I have never heard of the Spit fire having problems with the stress of firing the 20mm and I am sure that something would have slipped out. You often mention the lack of ammunition. A few early 5B's only had 60 rds per gun but early in the war all 20mm only carried 60 rds. Zero's MS406, De520, Spit 5, 109E, Whirlwind, P39, even the P38, they all started with 60rds per gun. However by mid 41 they all developed belt feed and this increased considerably. In the case of the Spit to around 140 rds per gun which was sufficient and similar to most other aircraft.

I do agree that the 303 would be pretty useless against a IL2, I think the Germans called them door knockers which seems to fit pretty well.

As for getting close pick your year.
If its early and you want the RAF to only have Spit 1 and Hurricanes armed with LMG then remember that the IL2 was slow, low and didn't have a rear gunner. There is nothing to stop you getting as close as you like. The I16 is agile yes, but slow, no good at altitude, poorly trained, no radio for communication. The ground control has no radar for direction or control. The VVS would only be good for pre planned opps or targets of oppertunity, it lacks flexibility.
If its later then we have 20's with a good supply of Ammo. Take your pick.