High altitude intercept: Spitfire and P47

fastmongrel said:

A quick look on the web and it seemed to have a very thick wing in proportion to width front to back.

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The wing's high thickness to chord ratio was the problem, at least that's the conclusion that Petter (who led the design team) and the A&AEE came to.





Cheers

Steve

Per the fighter escort discussion for 8th AF.. A fighter group positioned squadron coverage in many different ways relative to altitude separation.. One common thread was at least one high squadron, which depending on visibility, was usually 3,000 to 5,000 feet above the center of the bomber wing/combat box it was assigned to escort. The other two squadron positions varied from level on either or both sides, or one level and slightly high pacing the boxes from tail to front.. or one out in front, one high 'essing' and one in trail, slightly high.

The high center provided flexibility to 'go downhill' and pick up speed from 300mph cruise, or respond to inbound attacks at 27-30000 feet with 109s at 32-350000.

Rarely, a lead squadron on a Sweep would be several thousand feet below the trailing squadrons with intent to close on detected German formations trying to assemble or even taking off.

On the other discussion, the limit to the attained 46,000 feet ceiling for the XP-51G with the 14 S.M. engine was lack of cockpit cabin pressurization

The thick wing per se would not be the root cause for maneuverability or aileron authority - but the absolute root cause for a,) early on compressibility drag onset, b.) movement of the CMac during the shock wave migration aft - causing the nose down pitch as well as the secondary pitch oscillation at high speeds and c.) probably the blanking out of tail surfaces as the shock wave disrupted flow behind the wing.

It is like comparing to the P-38 developmental issues from 1939 to 1944.

I took a look on Brian Cull's Fighters over the Aegean, and there was at least 2 Ju 86s shot down by Spits in MTO,
on 6-Sept-42 P/O GEC Genders and P/O A. Gold hit the Ju86R1 5101 of 3(F)/123, which crashlanded with 60% damage at Bir el Abd following Feindbeschuss. Germans blew up the wreck when they retreated from the area.
on 2-Jul-43 P/O J. Hunter P/O GT Pratley (80 Squadron) and two pilots of 103 MU Ju86 (4U+IK Ltn Franz Stock crew MIA). Brian Cull had made a typo in his message to another board, typing Ju 88 instead of Ju 86, according to his book and Larry deZeng's message to that board the plane was a Ju 86. And in his book Cull mentioned that the crew of two didn't survive, so clearly a Ju 86 and not a Ju 88.
and then on 29-Aug-1942 Ju-86R or P (Werk Nr.5144) of 2(F)/123 on the returnflight, about 150 km north of Alexandria in Egypt one engine failed at an altitude of 10500 to 11000 meter. About 1000-2000 meter below was an English fighter, but the crew did not see any gunfire, so they thought that it was a mechanical failure. But 103 MU Spits flew in pair, lower flying "marker" with radio and higher flying "striker" without radio. P/O Genders had opened fire on the Ju 86 but his guns jammed after a short burst, so difficult to say. Did the Germans see only the "marker" and didn't notice few .303 hits or did Genders miss and it was a genuine mechanical failure?

One reads of low, medium and high altitude. What altitudes are these?

wuzak said:

I just quickly glanced at a few combat reports from the 303rd Bomb Group USAAF.

Mission 213: 28/7/44, Target: Leuna Synthetic Oil Plant at Merseburg, Germany, Bombing Altitudes: 26,200, 25,200 24,200 ft
ft

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Steve - using 7/28 as an example, my father was leading the 355th Group escort to 1st BD. The first combat encounter was between the 358FS/358FG flying high cover with McElroy leading while flying at 28,000. They first observed inbound FW 190s at 30-31K with 109 high cover at 33,000 feet - 8 FW 190s dove on the bombers, while eight 109s stayed at 33,000 feet hoping all the 358FS would go after the first section of the German formation. McElroy took his Red flight down and shot down Hirschfeld's 190 (Stab, JG/300) then destroyed a 109 fleeing from another flight. My father was leading at 26,000 feet out in front when six more 109s attacked behind the 354FS and in front of the 358FS about 20 minutes later near Mulhausen. He started the chase with his wingman at 26K and fired continuously in short bursts. The 109 went through cloud cover and crashed. Unknown whether dead, or out of control as he passed through the low cloud deck at high speed.

Only points to be made are 1.) bombers were high (as the B-17s nearly always were for heavily defended targets like Merseburg area), 2.) the escort fighters were as high as the highest bombers out in front and higher for the top cover by several thousand feet, and 3.) the LW, when they could organize in time with good target forecast, would nearly always try to have an altitude advantage and trade altitude for speed on the attack.

Many encounter reports center around the fight altitude, or the altitude at which they started shooting.

None of which alters the fact that Luftwaffe combat reports consistently describe the bomber formations flying in the 6000-8000m range. I say combat reports advisedly because the altitudes from which the bombers were sometimes shot down, and which are given in claims, are sometimes much lower.

For example:

Otto Stammberger, 6/10/42.
"They [the bombers] were in three levels up to 6,000m, but the individual vees were scattered. Above them were fighter condensation trails."

Georg-Peter Eder, 30/12/42
"I attacked a Fortress flying at 5,000m at the left of the formation from the left..."

Willhelm-Ferdinand Galland, 26/6/43, he attacked the escort.
"Approaching over the sea and out of the sun at 7,000-8,000m, I attacked a formation of Thunderbolts that had just arrived to take over the escort of the enemy bomber formation."

Erich Hondt, 17/7/43
"I scrambled with four Bf 109 Ts at 0848 hours and quickly made contact with the enemy flying at 7,500m."

I think late in the war the altitudes did increase slightly.

Robert Jung 13/9/44
"We flew North and were at 8,000m when we met the B-17s at the same altitude with their escorts 1,000m above them."

Willi Unger 7/10/44
"At 12.06 hours and 8,000m altitude, our Gruppe made an attack on a pulk of ca. 30 Boeing Fortresses from directly behind them."

Willi Reschke, 21/11/44
"The leading bombers were already south of us and it would be hard to reach the ordered 8,000m in time to attack the stream."

Robert Jung, 24/3/45
"We contacted the enemy flying at about 6,000m. This was unusual. We believed (incorrectly) that they were not so much as bomber escorts but as fighter bombers, but they were waiting for us."

Walter Schuck, 10/4/45, flying an Me 262.
"We were directed to climb to 8,000m over Oranienburg to meet heavies coming from the northwest. Escorts were patrolling above like a swarm of hornets. To get through them to the bombers, I led my Staffel on a zig zag course to 10,000m and brought them behind the bombers in a broad curve. We then attacked the Flying Fortresses from above."

I've picked these at random, the only criteria being that the height of the US aircraft is stated or can be worked out. In all the reports I have read there is not one in which an altitude of 9,000m (29,000+ft) or above is mentioned for the bombers. Obviously not every raid was intercepted, particularly late in the war, and not every report gives the altitude of the bombers when first sighted, though they usually give an altitude from which an enemy aircraft was shot down, not the same thing. Nonetheless, throughout the war, it seems altitudes above 8,000m (26,000ft) were not common place and altitudes slightly lower were more frequent until late in the war.

Cheers

Steve

Steve - all good insight to the evolution of tactics by the 8th AF. When sub pens were tasked in 1942 the B-17s went as low at 15,000 feet for better accuracy and were hammered by flak. When Lemay though the combat staggered box formations and flak hazard from 88mm - he arrived at 24,000+. Even B-24s flew at that altitude until it was clear that disparate cruise speeds and increasing lack of controllability of the B-24 at B-17 altitudes forced the 24 to 20-22000 feet while the forts stayed at 24-27000. Only the RAF tried 30,000 feet in a Fortress to little avail.

The B-17 strike zone for cruise speed was 150-155 mph IAS at 25,000 feet. The B-24 operated frequently from 18,000 to 22,000 feet at 170 TAS