P-51's vs. Me-109's and Fw-190's

[wmaxt]

Originally Posted by FLYBOYJ

Who was the second source?

Consolidated Vultee in Nashville, Tn. 113 Ls were built there. They had been building some sub assemblies before that (Wings and tails?) for a while.

wmaxt

[FLYBOYJ]

Never knew that! I worked at Plant B-1 in Burbank where the bulk of P-38s were built. There was a runway outside the facility which was located about 2 miles from Burbank Airport. After the war Lockheed converted that runway into a parking lot. There was also a P-38 final assembly line right at Burbank Airport in Building 304.

I was there right before they closed the facility in 1990. Some of the facilities folks found a wing jig that was sealed in a room (someone decided to brick the thing in a small room). It turned out it was a jig for a Hudson or a Ventura. I don't know what happened to it, it wouldn't surprise me if some bone head disposed of it!

[wmaxt]

Originally Posted by FLYBOYJ

Never knew that!

Think about this:

P-38K winter '43
432 METO at 29,600ft and 40mph faster than a J at 40,000ft.
Est. service ceiling of 48,00oft (on an Extreamly hot day 45,000ft was done)
4,800ft/min initial climb Fully loaded in Meto power
20K in 5min flat - FROM A STANDING START ON THE RUNWAY in METO.
Dive Flaps
A Second source

if All this started in '43/'44 it would have effectively trippeled the number of the number of the best P-38s available for the rest of the war.

The War Production Board said No to the 2 WEEK delay the K needed to fit into the line. The WPB didn't start a second line until '45. The WPB also rejected the simplified fuel controls that would have given the P-38L the ability to cruise economicaly over 300 mph too.

wmaxt

[plan_D]

The P-38K was really specialised for high altitude combat though, wasn't it? I always the thought the P-38L would be the best all-rounder P-38 because with the extreme high altitude performance of the K - it lost some it's low altitude abilities.

Am I right? I don't quite remember what it lost though.

[wmaxt]

Originally Posted by plan_D

The P-38K was really specialised for high altitude combat though, wasn't it? I always the thought the P-38L would be the best all-rounder P-38 because with the extreme high altitude performance of the K - it lost some it's low altitude abilities.

Am I right? I don't quite remember what it lost though.

The changes were to add 1,875hp WEP engines and wider/longer/High activity Propellars. The P-47 gained performance at low altitudes with those same mods there is no reason the P-38 wouldn't have too. Also the increase in climb figures start at sea level, all other attrabutes of the J/L models would also be included. The performance was additive.

wmaxt

[FLYBOYJ]

Originally Posted by wmaxt

Think about this:

P-38K winter '43
432 METO at 29,600ft and 40mph faster than a J at 40,000ft.
Est. service ceiling of 48,00oft (on an Extreamly hot day 45,000ft was done)
4,800ft/min initial climb Fully loaded in Meto power
20K in 5min flat - FROM A STANDING START ON THE RUNWAY in METO.
Dive Flaps
A Second source

if All this started in '43/'44 it would have effectively trippeled the number of the number of the best P-38s available for the rest of the war.

The War Production Board said No to the 2 WEEK delay the K needed to fit into the line. The WPB didn't start a second line until '45. The WPB also rejected the simplified fuel controls that would have given the P-38L the ability to cruise economicaly over 300 mph too.

wmaxt

Wow - Politics?!?

[Soren]

Originally Posted by FLYBOYJ

All good but C/L - max is rarely considered except during engine out emergencies and figuring out best glide over a distance (or unless we're talking about gliders). I assume these numbers are meant to be a ratio (1.48 to 1, 1.12 to 1, etc.) If so if you're gliding in either of these aircraft you better be doing it close to home because those numbers show both of them glide like a brick. The 1.48 to 1 (for the -109) , that means for every foot "down" you're moving forward 1.48 feet, and with those numbers shown I'm assuming it means that the -109 glides an extra 4 inches forward better than the Spit!

FJ,

CL-max is for figuring out the max lift pr area the wing will produce, it has nothing to with glide distance. However all else being equal, the higher the CL-max is, the longer the a/c will naturally glide, as there is then more lift pr area.

With the CL-max figure we can figure out the a/c's Lift-loading by dividing it with the Wing-loading. Example: An a/c with a Wing-loading of 27 lbs/sq.ft. and a CL-max of 1.30, will have a Lift-loading of 20.8 lbs/sq.ft..

Deploying Flaps will normally increase CL-max with a factor of 0.05, while slats by 25% of the original figure. Example: (All using the same airfoil and wing shape.)

Un-slatted wing CL-max: 1.30
Slat equipped wing CL-max: 1.62,5

Un-slatted wing with Flaps deployed CL-max: 1.35
Slat equipped wing with Flaps deployed CL-max: 1.67,5

[Soren]

Originally Posted by Glider

The November 1944 edition of the Flight Handbook for the K4 states that the max pressure boost was 1.75.
Orders from the OKL ChefTLR F1. E. 3V reported that tests at 1.98 couldn't be reported as the engines failed.
Daimler Benz reports that 1.98 boost not released due to failure of all the engines for the test (internal memo 6642)
Memo 6730 testing to be undertaken at 1.98 by Group 2/11 but only 1.8 engines supplied for combat with strict punishment if this is ignored. This memo also refers to the Mustang copmparison
Meeting held at Rechlin on 16th Jan concludes that 1.98 is not to be used on front line. Memo 6731

The comment about the top speed is based on the Projektburo estimate of 19.1.45 using a 9-12159 prop. The experimental one was a 9-12199 Dunnblatt.

I attach copies of memo 6730 and 6731. My German isn't that good so feel free to comment in case I got anything wrong.

Oh dear, you used Mike Williams as a source.... Sorry but Mike is VERY wrong, and his interpretation of German documents is awfully incorrect !

Back to the issue of maximum allowed boosts......

The manual for the DB 605 DB/DC engines issued 5th December 1944, the 3rd edition of it`s kind, notes the use of both 1.8 and 1.98ata for the DB/DC, respectively. According to the recordings of a meeting on the 20th January 1944, after unsuccessfull trials at Rechlin Test Centre, the clearance of 1.98ata was delayed until further testing is performed; particular interest is Gen. Ing. Paul`s criticizing Daimler Benz as it forwarded the clearance of 1.98ata boost directly General Galland, General of the Fighter Arm, and the Technisches Ausendienst for 'diese Leistungen direkt der Truppe angeboten wurden und die Motoren umgestellt werden' or because it issued these boost (1.98ata) directly to the troops and set the engines to it. Further the document states that individual fighter-recons may be set to 1.98ata. Given the date of the manual and the meetings and their contents, we can be sure 1.98ata was already in use for some time during December until late January, when the boost was recalled for further testing with II./JG 11.

[FLYBOYJ]

Originally Posted by Soren

FJ,

CL-max is for figuring out the max lift pr area the wing will produce, it has nothing to with glide distance. However all else being equal, the higher the CL-max is, the longer the a/c will naturally glide, as there is then more lift pr area.

With the CL-max figure we can figure out the a/c's Lift-loading by dividing it with the Wing-loading. Example: An a/c with a Wing-loading of 27 lbs/sq.ft. and a CL-max of 1.30, will have a Lift-loading of 20.8 lbs/sq.ft..

Deploying Flaps will normally increase CL-max with a factor of 0.05, while slats by 25% of the original figure. Example: (All using the same airfoil and wing shape.)

Un-slatted wing CL-max: 1.30
Slat equipped wing CL-max: 1.62,5

Un-slatted wing with Flaps deployed CL-max: 1.35
Slat equipped wing with Flaps deployed CL-max: 1.67,5

Totally understand and agree, but in the pilot world C/L max is looked at in terms of glide performance and is demonstrated during engine out glide. A pilot couldn't care about wing loading or lift loading but mention C/L max and engine out glide performance dances in their heads, especially if we're talking multi engine aircraft. Many aircraft pilot manuals (and I'm talking from a Cessna 150 to a DC-9) I've seen have this expressed on a graph showing glide distances based on altitude. When the CL max is shown on these charts it is expressed in a glide ratio 3.2 to 1, 5 to 1, 10 to 1. As you say yourself "the higher the CL-max is, the longer the a/c will naturally glide, as there is then more lift per area." To a pilot, it's all about being able to glide and if we're talking sailplane, it means everything.

With all that said, if the numbers shown for the Spit and -109 are ratio based on max glide (or max lift loading) over a given distance, both aircraft glide like bricks!

[Glider]

Soren
So what your saying is that 1.98 boost was authorised by DB, then that authorisation was withdrawn due to the unsuccessful tests, and Daimler Benz were critisised for incorrectly making the authorisation in the first place.
As a result your statement was correct ie. that it was used albeit unofficially.
Can I ask what happened after the authorisation was withdrawn?

[Soren]

Originally Posted by Glider

Soren
So what your saying is that 1.98 boost was authorised by DB, then that authorisation was withdrawn due to the unsuccessful tests, and Daimler Benz were critisised for incorrectly making the authorisation in the first place.
As a result your statement was correct ie. that it was used albeit unofficially.

Yes, however only minor problems were experienced in the field, such as the current sparkplugs thermal resistance.

Originally Posted by Glider

Can I ask what happened after the authorisation was withdrawn?

It was quickly autherised again after it had been withdrawn, no more than a month after actually, and with new sparkplugs.

Olivier Lefebvre states:
AFAIK 1.98ata boost was cleared late February but it seems to have been slowly introduced into service, I suspect the adjustments needed on the engine and the change of sparkplugs type (supply problems ???) took longer than expected. From other documents I know that C3 and B4 had severe quality problems beginning in late 1944. While it was not much of a problem with low boost, it had some serious effect on higher boost, so it might also have slowed down the introduction of 1.98ata boost. At least DB documents underlined the need for cleaner fuels than those in use at that time. You can safely assume that by March 1945 1.98 ata boost was being introduced, unfortunately I do not have much details for April 1945, but I doubt it would have changed much, given the situation.

[Soren]

Originally Posted by FLYBOYJ

With all that said, if the numbers shown for the Spit and -109 are ratio based on max glide (or max lift loading) over a given distance, both aircraft glide like bricks!

Yes they would have been awfull Gliders, which is why they had engines, to keep the speed up.

Anyhow Lift-loading is what people should be looking at when comparing a/c's turn-performance with each other, instead of Wing-loading which is totally misleading.

[FLYBOYJ]

Originally Posted by Soren

Yes they would have been awfull Gliders, which is why they had engines, to keep the speed up.

The the ability of an aircraft (with an engine) to glide (simulating an engine failure) and managing that glide to a safe emergency landing is a major emergency perfomace characteristic. This is a big part of the aircraft pilot checkout. Even though your numbers show the -109 was a little better, we're probably talking feet between the two.

[Soren]

Originally Posted by FLYBOYJ

The the ability of an aircraft (with an engine) to glide (simulating an engine failure) and managing that glide to a safe emergency landing is a major emergency perfomace characteristic. This is a big part of the aircraft pilot checkout.

Absolutely.

But my and your point was that without sufficient speed (Provided by the Engine) the 109 and Spit wouldnt fly, they would simply plummet like a brick Gliders have very high aspect ratio wings which provide an incredible amount of lift for their size, enabling them to fly unassisted once airborne, but their wing aspect ratio is also more than twice that of the 109.

Originally Posted by FLYBOYJ

Even though your numbers show the -109 was a little better, we're probably talking feet between the two.

With slats un-deployed the Bf-109 will stall a tiny bit later than the Spitfire, thanks to its lower Lift-loading. With Slats deployed, the 109 will stall even later yet, and at a higher AoA. This higher AoA can be a disadvantage upon landing though, as the forward vision gets severely restricted.

[FLYBOYJ]

Originally Posted by Soren

Absolutely.

But my and your point was that without sufficient speed (Provided by the Engine) the 109 and Spit wouldnt fly, they would simply plummet like a brick Gliders have very high aspect ratio wings which provide an incredible amount of lift for their size, enabling them to fly unassisted once airborne, but their wing aspect ratio is also more than twice that of the 109.

With slats un-deployed the Bf-109 will stall a tiny bit later than the Spitfire, thanks to its lower Lift-loading. With Slats deployed, the 109 will stall even later yet, and at a higher AoA. This higher AoA can be a disadvantage upon landing though, as the forward vision gets severely restricted.

Agree!