improving the 109??

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GregP said:
The .303 surely is accurate beyond 250 meters.
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The cartridge sure is. The guns may very well be. The problems are the mountings, the gun sights, and figuring out where the target is going to be when the bullets get there. A 300mph airplane is covering about 440 feet per second. If the bullet takes 0.3 seconds to reach the target the plane will have moved 132 feet or about 4 to 4 1/2 plane lengths for a fighter. Adjust target speed, bullet flight time and target size as you see fit.
 

Quite true, if you do things in the wrong order you can screw things up big time. However how hard do you have to work at screwing things up big time?
I can find no mention of a ignition timing control on an early Spitfire. I haven't looked at later ones.
On the MK II Spitfire the mixture control and throttle were interlinked to prevent the the engine from being run on an unsuitable mixture.
On Late model MK V Spitfires there is NO mixture control and the early ones had the same set up as the MK II, interlocked mixture and throttle.
So basically the Spitfire pilot had to worry about two controls. Throttle and Pitch. UNLESS he deliberately tried to force the controls into potions they were not supposed to go in (break the interlock).

The Pilots Manuals/notes are in the technical section of this website.
 
Shooter8 said:
So if the BoB Hurry was adequate, the Much faster and more powerfully armed P-40 should be much better.
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Except that the P-40 would have been no good for the BoB since none would have got to a squadron in time.

And the P-40 lacked self sealing fuel tanks, armour and its armament wasn't all that great in the BoB period.

I think that by the time the P-40 was turning up in numbers in the UK the RAF were trying to move to 20mm cannon for the Spitfire and Hurricane.

By the time Kittyhawk Is had been delivered to the UK the RAF were largely equipped with the Spitfire V. And the Spitfire IX was only 6 or so months away from entering service.
 

OH boy again:
The information about the XP-40 is irrelevant to the discussion. The ONLY differences between a P-40D and a P-40E was that the E had 3 guns in each wing and deleted the provision for slinging a 20mm gun under the wing. However with the D rolling out the door on July 1941 it is about 10-11 months late for the BoB.
BTW the Chin airscoop grew "larger" because the engine used in the P-40D/E used a different reduction gear (spur instead of epicycle) which raised the propshaft 6 inches. The radiators/ oil cooler and bottom of the cowl stayed pretty much in the same place. Not sure how the Allison got larger? the Engine used in the D/E used just about the same supercharger as the older engine and the same gear ratio. It was allowed to use higher boost which raised the power to 1150hp at 11,700ft but until WEP ratings came into effect (in 1942) the "official" power really wasn't much different than the earlier engine. going higher than 11,700 ft caused to the power to drop to about the same level as the older engine.


Chances of hitting at 1800 meters is about the same as wining the Powerball lottery. NO P-40 had two .50 guns in the cowl and any .50 cal in the wings so you are talking about a non-existent aircraft.
 
Hi Neo,

The Merlin and Allison were both fixed-timing engines ... most of the time.

How about a Merlin II for an "Early Merlin?"

Normally the Merlin II had two engine controls for the pilot; the throttle and mixture. Under exceptional conditions, a third control that cut out the boost regulator could be used and, when so-equipped, there was a fourth control for prop pitch when there was a variable-pitch prop installed. There were service requirements daily, after 10, 20, 40, and 120 hours.


The magneto timing was variable, but not directly by the pilot. It had an attached linkage that moved with the throttle. When in takeoff position, the timing was 45° BTDC for the exhaust plug and 38° for the intake plug. At idle it was less, but not by too much. The travel was linear and not "adjustable" other than by the throttle setting.


In the Allison, Shortround was right, 34° for exhaust and 28° for intake plugs. It was fixed for most of the Allison production run, but some could be retarded for starting. Once you know how to start one, it isn't necessary and neither are backfire screens when you know how to run one. In training, I'm sure backfire screens might have been useful to prevent engine damage by raw trainees who hadn't started an Allison at least a few times correctly. Once you learn it, the procedure is simple.

As for the .303, the round is accurate to much longer than 250 meters and the mounts are just fine. The real culprit was the crew chief. Many crew chiefs set the guns to have a sort of spray pattern at synchronous range, so the pilot would get at least SOME hits. The really good shooters stayed with the aircraft when the guns were zeroed, and insisted they be set to hit a single small spot at the synchronous range.
 

The Prima Facie argument trips over it's own feet and does a full face plant when you actually look at the specifics. The Top scoring British ace only flew about 700 missions compared to Hartmans slightly over 1400 missions. More importantly Hartman was involved in about 825 engagements to get his 352 victories for a "success ratio" of 42.6%. Johnson was only engaged in combat just 57 times. You can't shoot down planes that aren't there. Johnson's victories (as listed by Wiki so....) Johnson was credited with 34 individual victories over enemy aircraft, as well as seven shared victories, three shared probable, 10 damaged, three shared damaged and one destroyed on the ground. They include 14 Bf 109s and 20 Fw 190s. Even at 34 victories Johnson had a "success ratio" of 59.6% flying Spitfires.

No disrespect to Hartman He was an exceptional pilot and an Honorable man from all accounts, being prouder of his not loosing wing men and squadron mates than his score.

Simple comparisons of scores to prove points without taking into account differences in theaters or fronts or time period in the war actually don't prove anything.
 
There are a couple of things to remember about the German victory totals. They may have been covered. If so, nothing intended or implied, just making the points.

1. Allied pilots rotated in and out. German pilots flew until the war was over or they died or were injured to badly to fly.

2. There were Allied targets all over the sky. The UK was bombing Germany and / or German targets almost from the end of the phony war onward. By late 19442 there were comparatively few German targets for the many Allied fighters to find. By mid-1944, there were almost no German fighters for the average Allied fighter pilot to shoot at. The few concentrated on the bombers and flew hit and run tactics. It didn't work. But the average German fighter pilot had NO TROUBLE getting into combat while the average Allied fighter pilot had a lot of trouble finding a German adversary on most mission.

Last, on the subject of the P-40, the later P-40s didn't get a bigger radiator to cool the big engine. It was the exact same displacement as the earlier P-40s were, 1710 cubic inches (5.5-inch bore and 6-inch stroke), It got the deeper chin because Allison went from the C-engines to the F-engines in the P-40, and it didn't have the long, skinny nosecase of the C-series. It had a shorter, deeper nose and was MUCH stronger and more reliable than the comparatively weaker C-series propeller gears were.
 
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stona said:
Gun harmonisation diagram for the Spitfire V. Another document unearthed and freely given for the benefit of us all by the late Edgar Brooks.


Cheers

Steve
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Thanks.
There was (is) another series of diagrams showing different ways to harmonise guns, from memory the FAA and RAF had different ideas the FAA having more of a spread
 
It may seem complicated to us to have ignition advance retard and fuel lean/enrichment but it was part of 1930s motoring even on motorcycles, the early TT racers used to start off with a tool kit and spare parts. It is convenient to have a control that does everything automatically but that doesnt mean doing it manually was an impossible or even difficult task, WW1 pilots had changing magazines and unjamming guns as part of their normal tasks.
 
Shooter8 said:
The Spit was easy for the average pilot to get the most out of the plane ...
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This brings up another knock on the P-40, unfortunately. In those desperate months in 1940, pilot training in the RAF wasn't exactly extensive. The fact that the Hurricane and Spitfire were, in the words of Molders himself, "very simple to fly compared to our aircraft, and childishly easy to take-off and land" was a definite asset.

After testing the Hurricane and Spitfire, the United States Army Air Corps concluded that both types "are easier for inexperienced pilots to fly than the American pursuit planes. The automatic boost control is a big help in that respect."

One of the top P-40 pilots of the entire war, James Francis "Stocky" Edwards, had this to say (about the Kittyhawk, granted, but I think everything would apply to the Tomahawk as well):

"In my estimation, the Kittyhawk Mk.I was not an easy aircraft to fly properly and, as a result, we lost a good number of pilots while training. Some Hurricane pilots flatly refused to fly it, preferring to go back to Hurricane squadrons. In the first few months after conversion to Kittyhawks, all the squadrons lost heavily to the 109s. It didn't seem to matter whether they were sprogs, sergeant pilots, or Battle of Britain veterans. The 109s still hacked them down.

Our pilots seemed to be at a great disadvantage trying to learn how to fly the aircraft while carrying out operational sorties. I'm certain this is why many of our experienced pilots were shot down. This was coupled with the rapid turnover of COs and Flight Commanders.

I found that one had to have a very strong right arm to control the Kittyhawk I during most manoeuvres ... in dive bombing, the aircraft would pick up speed very quickly in a dive, but it had a great tendency to roll to the right. One could trim this out reasonably well with the left hand, but even then, when one pulled up, it wanted to roll to the left quite violently. So I learned to trim out about half-way in a dive and hold the control stick central by bracing my arm against my leg and the cockpit wall. I found I had more control this way and didn't have to take off so much trim when pulling out and the speed was reduced. It was also distracting to have one's left hand on the trim all the time, when it should be on the throttle.

... in a dog-fight with violent changes in speed, it was all one could do to fly the aircraft. Since the Kittyhawk would fish-tail and skid violently if not flown smoothly, there was little chance of hitting anything, so I had the mercury ball portion of a needle and bank instrument placed right below my gunsight. That way I could see it all the time without staring at it - it took all the guesswork out of flying smoothly. In every aircraft I flew on operations to the end of the war, I had my groundcrew install this instrument below the gunsight.

The Kittyhawk Mk.II (F series) with the Packard-Merlin engine was a definite improvement in lateral stability over the Kitty I."
 
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There were different opinions about how the guns should be harmonised and at what range. Following trials at Shoeburyness in the early '30s, before an eight gun fighter had been built, there was a large body of opinion in favour of harmonising all the guns at one point and specific range.

In August 1931 air firing trials, carried out at Dowding's behest, had shown that:

"The multi gun type of fixed gun single seat fighter is more likely than the two gun single seat fighter, to produce the density of fire necessary to ensure a hit on a vital part of a target aircraft, in a time which approaches the actual average time during which aerial targets present themselves in air fighting."

In September 1933 another reason for increased fire power was advanced by Ludlow-Hewitt in a letter to the Chief of the Air Staff.

"The number of single seat fighters which can attack a large bombing formation simultaneously would probably not exceed one third of the number of bombers, hence the need for the single seat fighter to develop at least four times the fire power of one bomber from the rear gun."

By 1934 everyone had settled on eight guns. At a meeting of the Operational Requirements Committee in August 1934, to discuss the 'Fury' replacement, the minutes note:

"It was agreed that eight guns should be aimed at on grounds of shorter time to obtain the required density of hits and the improvement in range which was obtainable with more guns."

It has been argued that the eight rifle calibre machine gun armament of British fighters in 1940 was ineffective, but the thousands of Luftwaffe aircrew shot down would certainly beg to differ. The armament did become less effective with the ever increasing armouring of the target aircraft, the move to a mixed armament including cannons was inevitable.
It is often argued that the Bf 109 E armament was better, and the 20mm cannon was certainly more destructive, however, it was only destructive if hits could be scored and with only two mounted and given its low (relatively) rate of fire and ballistic properties, and the limited time in which targets presented themselves, scoring those hits far from certain.

Cheers

Steve
 
I would add several things to the above.
One is that the armament of eight .303 guns and ammo was one of the heaviest (weight of installation wise) of the time 1938-mid 1940 for service aircraft. This shows that the British were very interested in firepower and as Stona has shown the planning/interest went back years.
Unfortunately for the British they had too many strange ideas floating around which confused things and apparently the earlier method of testing things seems to have fallen behind a bit. Gunnery training seems to have been a bit neglected and some of the aiming patterns/harmonization schemes were designed to make up for poor marksmanship at the cost of concentrated fire. A little too much emphases on quantity instead of quality even in prewar years. Or some belief in the idea that pilots could not cope with 300-500mph closing speeds?
The effectiveness of the .303 battery could also have been much improved by the use of different ammo. Again a production problem and a consequence of the change to protected aircraft. In 1940 there was a shortage of .303 AP ammo so only one gun (or sometimes two) out of eight had the AP ammo. British .303 AP ammo proof test was 70% of the bullets had to penetrate a 10mm plate at 100yds range. Obviously proper .303 ammo could do more than poke holes in sheet aluminum.
Likewise there was a shortage of incendiary ammunition, and no, tracer does does not make a good incendiary round.

I would note that it gets frustrating arguing with some 109 fans because the 109 keeps changing to suit the argument.
The 109 in the BoB used wing 20mm cannon, There were NO engine mounted cannon so the 109 had pretty much the same convergence problem (or not, convergence is a much overblown factor) as the allied aircraft. Something the German fans like to mention as little as possible is the different flight times of the German guns and ammunition making concentrated fire at distance, especially in deflection shooting difficult.
I have mentioned this a number of times before but figuring out the convergence thing is simple geometry. If you have guns 12ft apart and a 300yd cross then the bullets are 8 ft apart at 100 yds. 4 feet apart at 200 yds. crossing at 300yd, back to 4 feet apart at 400yds and 8ft apart at 500yds and back to 12 ft at 600yds. If the intended target is a He 111 just how far apart do the bullets have to be in order to have most of them miss? or even a Do 17?
Getting the aiming mark of the gun sight on target and figuring out the necessary lead (speed and course of target) and distance are much greater factors than wing or fuselage guns.
 
The effectiveness of the .303 battery could also have been much improved by the use of different ammo. Again a production problem and a consequence of the change to protected aircraft. In 1940 there was a shortage of .303 AP ammo so only one gun (or sometimes two) out of eight had the AP ammo.
.[/QUOTE]

Sources differ, but either three or four of the eight guns were loaded with ball ammunition during the BoB period. One wonders why any were loaded with this , given the results of the British' own experiments up at Orfordness! I can only assume, as above, that there was a shortage of the Mk IV and Mk VI incendiary rounds as well as the AP rounds and a couple of pounds per second (from four guns) of ball ammunition might cause some damage.
Incidentally the Mk IV incendiary also served as a tracer round, but was only 50% as effective as the Mk VI at igniting target fuel cells in tests.

The ammunition capacity of the British aircraft is often criticised. The Spitfire had enough for 16 seconds of continuous fire. Not much? Hold your breath and count 16 seconds.

The two factors that outweighed all others in British thinking as they developed fighters through the 1930s were speed and fire power, other considerations, including range/endurance were secondary. It's why they ended up with the Spitfire, Hurricane, Defiant (and Whirlwind).

Cheers

Steve
 
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Hosing an area sky hoping to hit an enemy aircraft is hardly effective use of ammo. 16-17 seconds of fire is is enough for 5 or so bursts of about 3 seconds each which was about all most pilots could hold an enemy aircraft in the gun-sight for (not somewhere in the gun camera frame) . Now how long in minutes does it take for an average pilot to get into firing position 4-6 times?
The Spitfire and Hurricane may have been a bit short on firing time but nothing like the 20mm guns using 60 round drums (around 8 seconds firing time) on the 109, the Zero, the French fighters of 1940 and yes, the early Spitfires with cannon and the Whirlwind. On some of these planes the 60 rounds lasted only 6-7 seconds.
Eight .303s were firing 145-160 rounds per second. Get them pointed into an area even 6 ft across and get that impact area onto an aircraft and there will be a lot of damage.
If you have pilots that are not well trained/practiced and open fire 2-3 times further away than they should then you need a lot more ammo.
.303 ammo weighed about 6.6lbs per hundred for belted ammo. going to 500rpg from 300rpg would have added about 107lbs to the gross weight. SO it depends on how much of hit you want to take to performance (climb) or what else you can take out.
I would note that the MK II Spitfire had gained about 350lbs in weight over an early MK I with wooden prop. The MK may have had an extra 50 rounds per gun.
 

OK, not to "cherry pick" (but apparently I will) I'm not buying the .50 cal as accurate at 1,800 meters using the technology that a 1940 fighter plane would sport. Maybe 10+ years after the BoB in the skies over Korea. I've talked with Sabre pilots that used the radar ranging gun sight on the F-86 to get strikes from 1,200 to 1,800 yards but unless your name was Foster or McConnell or Jabara etc. they were strikes, not kills. Using what was available in 1940 (not the 1940's) was only going to allow nothing but a lucky hit at 1,968 yards. (1,800 meters)

Also, the P-40 as an RAF interceptor? Uh, last I checked, for 1940 BoB you had to be able to climb like a bat outta hell for any kind of success, not that I was there but from what I gather that's not the P-40's strongest selling point.

Pete
 
You would be correct in your assessment.
I have some ballistics tables for old .50 cal ammo (and there is a difference between M1 ball and M2 ball) and time of flight for 2000yds given a 2700fps muzzle velocity is 3.72 seconds. time of flight to 1900yds is 3.44 seconds and time of flight to 1800 yds is 3.17 seconds. Granted this is at sea level and at altitude the times would be shorter due to less air resistance but it gives a good idea of the problem. a 10% change in range means a 17% change in time of flight. And how far can even a 150mph (220fps) bomber fly in just 3 seconds? 660 feet?
And of course our eagle eyed pilot was able to figure out the exact speed and course of the target
being off by 1 degree means even the slow bomber is around 15-16 ft to the side of where eagle eye thinks it will be. Can you tell if you are exactly at the targets 180 degree position at 1800-2000yds or if you are at it's 179 degree or 181 degree positions?
Angle of decent at 2000yds is 53.9 mils or just over 3 degrees so the bullet is dropping about 15 ft in 100yds. Is the plane at 1950yds or at 2050yds when the bullet arrives?

M2 ball and M2 AP was slightly higher in MV (but used a slightly lighter bullet) and the less dense air will slow the bullet less.
AS another bit of ballistic trivia the M1 Ball/AP with a bit lower MV (24-2500fps) rose to a point 72.5 feet above the line of sight on it's way to to 2000yds.

edit. Ballistic data from the book "Ammunition" by Melvin M. Johnson and Charles T. Haven copyright 1943 pages 213 and 295.
 
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