Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)

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P-39 Expert said:
Trying to supply three different ammo types was insane. Especially when the .30s had an effective range of only 200yds (AHT).
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Yep, real insanity, considering that the .30 cal ammo was used by the ground army tripod mounted Browning machine guns, both air and water cooled, the BAR, the M1 Garand, the 1903 Springfield (and variations) and the 1917 Enfield. In 1941 the standard mix of ammo for the ground machine guns was 10%AP, 20% tracer and 70% ball ammo. Getting .30 cal ammo might have been a much smaller problem than getting either 20mm or 37mm ammo. Might not be the preferred types but getting something seems to be pretty easy.

I would love to see a definition of "effective range" as used in AHT. The max range of a .30 cal Browning with M2 ammunition (150 grain flat based bullet) was about 3,500 yds and the max range using M1 ball (172 grain boat tail) of about 5,500 yds. effective range is certainly much shorter than max range.
However the US Army penetration tables show the M1 ball at 200yds going through an average of 7 in of gravel, 4 in of concrete, 13.8 inches of solid oak, 6.5in of dry sand. These are average penetrations, individual shots sometimes penetrated more.
I doubt the duralumin skin of most single engine planes is going to stop the .30 bullet.

A different table for the older 1906 load which was just about identical to the M2 ball ammo claims to would completely penetrate 1/4 low grade steel plate at 400yds. Low grade steel is not armor but then, depending on the angle of impact and deflection caused by the aircraft skin most aircraft structure and engine/cylinder blocks are not going to withstand that force of impact most of the time.

All penetrations are pretty much sea level and would improve at higher altitudes.

Not saying that the .30 cal (or .303) was anywhere near as effective as the .50 cal but the idea that the .30 cal bullets cannot inflict damage or are useless at anything beyond 200yds needs to go away and stay away.
 
Milosh said:
I guess Expert doesn't know about the interception of HIGH flying German recon airplanes by Spitfires.
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Or the recon planes carrying bombs which would be called bombers to the people who had the bombs dropped on them. In fact there were also high and low altitude Jabo raids throughout the BoB but they weren't part of the main story and weren't decisive so get little attention, the fact is they happened and were an issue for Park to deal with, as they were supposed to be.

Even the potted history of Battle of Britain, 10 July-31 October 1940 says this.
Phase 5 - 1-31 October

The final stage of the Battle of Britain saw the Germans abandon large scale daylight raids. Instead they focused on small-scale low level raids by Ju 88s and high-level fighter bomber raids, using bomb-carrying Bf 109s supported by pure fighters.
 
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You are confusing combat ceiling and service ceiling, you are also leaving out operational ceiling (climb is 500fpm). It was not uncommon for the British and German fighters to fly at around 30,000ft in the BoB. Not uncommon does not mean common or standard practice, it just means not uncommon.
The reason is at much over 20,000ft the fighters that had the altitude advantage had a major combat advantage. They did NOT FIGHT at 30,000ft but the planes with the altitude advantage could break contact/refuse combat easier. They could trade their altitude for speed (energy) by diving down on their opponents. They could keep going (boom and zoom) and since they were already flying faster in their dives (even if shallow) they were harder for the lower starting altitude fighters to follow. If the diving planes decided to turn they had more speed to burn in the turn before their airspeed fell too low.
For the British, if you know that some of the German fighters are coming in at around 30,000ft (certainly not all) do you just say "Oh well, we will continue to fly at 24-26,000ft and let them bounce us on occasion" or do you try to get some (not all) of your fighters up to 30,000ft to equal the high flying Germans and/or bounce the Germans that come in at 25,000ft or so?
A major part of the rational behind the Hurricane II with the Merlin XX engine (deliveries started in Sept 1940) was to improve it's altitude performance, They figured the Merlin XX engine would change the operational ceiling (500fpm climb) from 31,400ft to 34,900ft, They figured this would keep the Hurricane competitive with the 109.

BTW, the bomber ceilings are often given at full load. For some of the early twin engine bombers burning off several thousand pounds of fuel can change their ceilings by a few thousand feet. You are the one who keeps telling us that just cutting a few hundred pounds out of the P-39 will add hundreds of fpm to it's climb rate and thousands of feet to it's ceiling.
 
Where you got the idea that "P-39s could match the LW fighters up to 8000meters (26400ft)" maybe even up to 17500 ft but after that P-39 N /Q began to run out of steam.
 
P-39 Expert said:
...The Soviets configured the P-39 without the .30cal wing guns and they thought it was a really good aircraft. Their favorite.
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Soviet removed 7.62 mm mgs pat of their P-39s but not from all, see my message XP-39 II - The Groundhog Day Thread, in June 44 clearly part of the P-39s of the famous 16 GvIAP still had their 7.62 mm mgs installed and loaded. That message was written over ½ year ago but for no good, it seems.
 

Well, since you've frequently quoted WW2aircraftperformance.org (Source: http://www.wwiiaircraftperformance.org/wade-ceiling.jpg), perhaps this table may help change your mind. It was originally published in The Aeroplane on 21 June 1946. Yes the Spitfire variants are much later than the MkI of BoB....but it would be a phenomenal increase to take an aircraft that, in 1940, couldn't best 25,000ft and then, just a few years later, attain 37,000ft (or thereabouts)...it's a big enough increase to go from 30K to 37K.



Can't you, for once, admit you are wrong about something? You're expressing an opinion and yet seem to be entirely unmoved by any evidence to the contrary. Again, you wonder why we call this the groundhog day thread.
 
Need I point out the P-39's small internal fuel load which limits its operational radius considerably? In the second half of 1943 the USAAF is rapidly realizing range is a vital component, and that's something the P-39 simply cannot supply.
 
P-39 Expert said:
These were personal accounts, amounting to heresay. Maybe they read their instruments incorrectly, or they were embellishing their story. I don't know.
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Sorry but these comments are just a bullshit excuse to avoid factual data that directly contradicts your "opinion." One of the quoted items was not a "personal account". It was an official post-mission report. Are you telling me that, straight after this sortie, Eric Thomas lied to say he was flying higher than he actually was? Are you also suggesting that his entire squadron, that he was leading on this mission, was in on the embellishment? Come on, that really is ridiculous.

Are you also suggesting that Alfred Price is lying when he cites the service ceiling of the Spitfire MkI as being in excess of 34,000ft?

Please just admit you are mistaken and maybe, for once, we can move on.
 
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Here is a report of a Spitfire I

Spitfire Mk I K.9787 Trials Report

Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.
www.spitfireperformance.com

In the climbing trials it estimates an absolute ceiling of 32,800ft, the service ceiling (climb 100ft/min) was 31,900ft and the maximum altitude reached on test was 32,400ft.

Time to climb to 30,000ft was 22.4 minutes.

The maximum speed at 30,000ft was 315mph.

Test was in January 1939. The engine fitted was a Merlin II, and the prop was wooden, fixed pitch.


With Merlin III and 2 pitch metal prop the estimated service ceiling was above 35,000ft. Time to climb to 30,000ft had gone up by a minute or so.

Spitfire Mk I L.1007 Trials Report

Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.
www.spitfireperformance.com

That was July 1939.


With Merlin III and constant speed prop, as tested in March 1940.

Spitfire Mk I N.3171 Trials Report

Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.
www.spitfireperformance.com

Speed at 30,000ft was up marginally to 319mph TAS, time to 30,000ft was down to 16.1 minutes. Service ceiling 35,800ft. Rate of climb was 660ft/minute.

This aircraft was 230lb heavier than the on in the first listed report.



With 2 20mm cannon and 4 0.303" mgs, weighing 300lb more than the previous example, this Spitfire I climbed to 30,000ft in 19.6 minutes, had an estimated service ceiling of 34,700ft and a climb of 570ft/min at 30,000ft.


Report dated 19 February 1941.
 

Brilliant stuff, Wuzak...I was hoping someone would have actual test figures for the Spit MkI. Thanks for posting these details.

Just to add to the evidence pile, the service ceiling for the Bf109E-3 was 11,000m or 36,089ft. "Die Dienstgipfelhöhe beträgt bei voller Ausrüstung 11 000 m." (Source: Kurfürst - Baubeschreibung für das Flugzeugmuster Messerschmitt Me 109 mit DB 601.)

Also, the service ceiling for the Bf110C-4 was 10,000m or 32,808ft (Source: Lexikon der Wehrmacht - Messerschmitt Bf 110)

So...anyone found any contradictory sources that put the service ceiling for these types at around 25,000ft?
 
He is referring to "combat ceiling", which he is saying is 1,000ft/min. I don't know if that is an official number or where he got that from.

For the P-39C that was slightly below 25,000ft. For the P-39D that was ~23,000ft.

For the Spitfire I of early 1940 that was ~27,000ft.

Spitfire Mk I N.3171 Trials Report

Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.
www.spitfireperformance.com

For the Spitfire V, with 2 x 20mm cannon, 4 x 0.303"mgs the 1,000ft/min climb was met at around 31,200ft.

The Spitfire V being more contemporary with the P-39C and D than the I.

The Spitfire tests were done by the A&AEE.

The early P39 tests look to have been done by the USAAC/F Materiel Command, but test of the later models start with "Report on flight tests of Bell P-39 airplane at the manufacturer's plant". Which begs the question, are those manufacturer's performance numbers, or performance tested by the air force?
 
ThomasP said:
To be fair, P-39 Expert said "Spitfire and 109E combat ceilings (1000fpm climb) were a little above 25000'. 110s about 21000ft." in his post#1,907 - not service ceiling.
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Yes, but it was in the context of his opinion that combat at 30,000ft being impossible in the BoB. Plenty of data has been provided to show that it was, indeed, possible and yet he refuses to accept it and ploughs forward with his "opinion".
 
P-39 Expert said:
a fuel powered cabin heater (when heating/cooling of the cabin was actually already very good)
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You might be interested to know that the heating of the cabin of the P-39C and D was very good because they used a Stewart-Warner gasoline type heater.

This is stated in the pilots manuals.

So, NO, the British did NOT load the plane down with useless stuff like a fuel powered heater, it was already there.
 
That's why it didn't make the list. Plus, it didn't see action with the USAAF. Wait, AVG/ 23rd FG had a few.
P-26 shouldn't be included either. They were assigned to the Philippine Air Force.
 
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